Applied Rheology: Publications

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Jan Ullsperger, Robert Valek
Properties of polymer solutions intended for formation of hollow fibers membranes by inversion phases process

Appl. Rheol. 28:6 (2018) 65935 (7 pages)

The gas separation process by asymmetric polymeric membranes has received much attention during the last decades because of its more energy efficiency than other conventional separation processes. Hollow fibers are the most favored membrane geometry owing to their high surface area per unit volume of membrane module. One of the key elements determining the potential and applications of asymmetric hollow-fiber membranes are the structural properties mainly including pore size, pore distribution, selective layer thickness, molecular orientation and defectiveness. These elements can generally vary depending on conditions during dry-Jet wet-spinning process. Flow conditions in spinneret during extrusion are known to affect the dense-layer of hollow fibers and possibly to enhance separation performance of hollow fibers. The aim of this study was to determine flow conditions of polyetherimide/N-Methyl-2-pyrrolidone solvent/ethanol non-solvent spinning solutions flowing through concentric annulus of spinneret during hollow fiber spinning process. The rotational rheometer was used to characterize rheological properties of spinning solutions. Newtonian behavior of the spinning solutions with arbitrary composition was shown. The effect of spinning solution and spinneret dimension on flow profile in spinneret was investigated. The Newtonian character of the spinning solutions caused constant velocity profile resp. shear rate profile regardless of dope composition when flowing through a spinneret with some flowrate. It has been shown the spinneret dimensions and geometry play a crucial role in controlling the shear flow in spinneret. The phase behavior of the PEI/NMP/EtOH dope system at a temperature of the hollow fiber spinning process (40oC) was studied.

Cite this publication as follows:
Ullsperger J, Valek R: Properties of polymer solutions intended for formation of hollow fibers membranes by inversion phases process, Appl. Rheol. 28 (2018) 65935.

In this research, a fully developed steady flow of a third-grade fluid in a pipe under an externally applied magnetic field with convection on wall is investigated. The governing equations including momentum and energy in the form of partial differential equations are reduced to ordinary differential equations which are solved numerically by using a finite element method (FEM) as part of the FlexPDE software package. For validity, the results are compared with the 4th order Runge-Kutta method. The effect of different physical parameters such as the non-Newtonian parameter, the Biot number, the Hartmann number, the Eckert number on the dimensionless velocity profiles, the dimensionless velocity gradient profiles, the dimensionless temperature profiles, and the dimensionless gradient temperature profiles have been discussed. It is concluded that by increasing the non-Newtonian parameter and Hartman number the dimensionless velocity, the velocity gradient, the temperature and temperature gradient profiles reduce and thus the heat transfer of fluid flow, the shear stress and the skin friction on the pipe wall decrease. Increasing the Biot number caused a decrease of the temperature and a more uniform dimensionless temperature profile of the fluid within the pipe. Besides, with a decrease of the Prandtl number, the dimensionless temperature decreases inside the pipe. In fact, the dimensionless temperature profile becomes flat. For this reason, the dimensionless temperature gradient decreases on the pipe wall which causes the reduction of the heat transfer rate on the pipe wall. Further, by increasing the Eckert number, the dimensionless temperature of the fluid within the pipe and the heat transfer from the fluid to the pipe wall increases. Applying the FlexPDE software for solving governing equations numerically seems to lead to appropriate and reasonable results.

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Javanmard M, Taheri MH, Ebrahimi SM: Heat Transfer of Third-Grade Fluid Flow in a Pipe Under An Externally Applied Magnetic Field with Convection on Wall, Appl. Rheol. 28 (2018) 56023.

Polytetrafluoroethylene (PTFE) micropowders were used to prepare PTFE-oil organogel. Carbonyl iron particles were dispersed in this organogel to fabricate magnetorheological fluids. The main aim of this paper is to investigate the influences on fieldinduced chains by non-magnetic microstructures inside these organogel-based MRFs. The field-induced anisotropy of MRFs between first normal stress differences to shear stresses and dynamic modulus reveal that organogel widen the non- Newtonian elastic range of MRFs as long as the non-magnetic particles content is appropriate. Both theoretical and experimental results of static and dynamic normal forces indicate that normal forces are influenced by magnetic and non-magnetic microstructures comprehensively. The dynamic normal forces are lower than static ones under low magnetic field strength while the phenomenon becomes opposite in the presence of high strength magnetic field. Moreover, a 3ITT test of normal forces exhibits a significant time-dependent behavior of the normal forces. The investigations of recovery ratio demonstrate that the non-magnetic microstructures help field-induced chains to recover at relatively low magnetic field strength but hinder this structural recovery at high magnetic field strength. Finally, a new investigation method on amplitude-dependent normal forces is introduced showing a four-region behavior as a function of strain amplitude, which reflects the internal microscopic evolution of MRFs and could be a proper way to study the influences on field-induced chains by non-magnetic particles.

Cite this publication as follows:
Zhang H, Hu Z, Yan H, Yang J, Niu F: The influences on field-induced chains by nonmagnetic microstructures inside the magnetorheological fluids Based on PTFE-oil organogel, Appl. Rheol. 28 (2018) 53921.

An approach of Nelson and Ewoldt [Soft Matter 13 (2017) 7578] to create a viscosity model of the Herschel-Bulkley type in order to use only parameters with the potential of containing fluid information has been extended to be applied to drilling fluids using current industry standard procedures. The commonly used Herschel-Bulkley consistency parameter k is found inadequate in describing fluid properties properly as it has a unit dependent on n. Hence, the model is not optimum for digitalisation. The Herschel- Bulkley model is re-written and base its parameters directly on the yield stress and the additional or surplus shear stress at a pre-determined shear rate relevant for the flow situation to be considered. This approach is also applicable for Power-Law models.

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Saasen A, Ytrehus JD: Rheological Properties of Drilling Fluids - Use of Dimensionless Shear Rates in Herschel-Bulkley Models and Power-Law Models, Appl. Rheol. 28 (2018) 54515.

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Galindo-Rosales FJ: 2nd Summer School on Complex Fluid-Flows in Microfluidics, Appl. Rheol. 28 (2018) 49.

In the current research, focus is on the comparison of Jackson and Tucker (JT) theoretical model to experimental results of large amplitude oscillatory shear (LAOS) of immiscible polymer blends. The field of rheology of immiscible polymer blends is currently very deficient in LAOS results, especially at moderate to low viscosity ratio values. In addition, most of the theoretical modeling that was carried out on LAOS of immiscible polymer blends used the small deformation theory of Maffettone and Minale. The current work adds further knowledge in the field of modeling of immiscible polymer blends by testing the predictions of the large deformation theory of Jackson and Tucker against LAOS experimental behaviour. LAOS experiments were carried out for a model immiscible blend composed of two Newtonian components (polybutadiene and polydimethylsiloxane) at viscosity ratios 1.34 and 0.39 and at volume fraction value 0.2. Data for the first, third and fifth harmonics of the sinusoidal stress response were recorded by FT-Rheological experimental set up. Validation of Jackson and Tucker model was carried out and the experimental results were compared to the JT model. Furthermore, the theoretical predictions of the JT code were compared to the experiments of Almusallam for two blends at viscosity ratio values of 0.1 and 4.4 at volume fraction value 0.21. The experimental results were plotted in terms of the scaling parameters of Reinheimer et al to test the scaling law. The Reinheimer scaling law was developed for viscosity ratio values larger than 2.5 and hence a new scaling law was developed in the current study taking into consideration the viscosity ratio values less than 2.5.

Cite this publication as follows:
Almusallam AS, Bini TB: Scaling Law Accomplished through Correlation of Large Amplitude Oscillatory Shear of Immiscible Polymer Blends with Jackson and Tucker Model, Appl. Rheol. 28 (2018) 46039.

Drilling fluid constitutes an important part of the drilling operations. Gel strength property of drilling fluids plays a key role in drilling multilateral and long horizontal reservoir sections. Losing the gel strength will accumulate drilled cuttings and as a result, sticking of the drill string. Solving this issue takes a long time and increase the total cost of the drilling operations. The obJectives of this paper are to (1) determine the rheological properties of calcium carbonate water-based drilling fluid over a wide range of temperature, (2) assess the effect of adding nanoclay, bentonite, and nanosilica on the gel strength problem associated with the current field formulation of calcium carbonate water-based drilling fluids, and (3) optimize the concentration of bentonite, nanosilica, and nanoclay in the drilling fluid. The concentration of bentonite, nanoclay, and nanosilica was varied from 1 wt% to 10 wt%. Rheological properties results confirmed that the gel strength of the calcium carbonate water-based drilling fluid reached zero lb/100ft2 by increasing the temperature to 200 °F (93.33 °C). This issue was solved by adding different concentrations of bentonite, nanoclay, and nanosilica. At low bentonite concentrations (3.33 wt%), the gel strength still reduced with time. At high bentonite concentrations (10 wt%), the gel strength increased with time. The optimum concentration of bentonite was 6.66 wt%, which yielded a flat rheology profile of the gel strength. These results confirmed that the rheological properties of the water-based drilling fluid were optimized by using bentonite. Similarly, 7.5 wt% nanosilica showed the optimum performance. Nanoclay was not effective in improving the rheological properties of the calcium carbonate drilling fluid.

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Elkatatny S, Kamal MS, Alakbari F, Mahmoud M: Optimizing the Rheological Properties of Water-based Drilling Fluid Using Clays and Nanoparticles for Drilling Horizontal and Multi-Lateral Wells, Appl. Rheol. 28 (2018) 43606.

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Baller J, Wagner C, Roose P: Joint Symposium Rheology - 360° of the Belgian Group of Rheology, German Rheological Society, and ProcessNet-Subject Division Rheology, Appl. Rheol. 28 (2018) 53.

Two geometrical models are developed to simulate fluid transport via peristaltic motion in tubes of uniform or linearly decreasing radius: A 2-D axisymmetric tubular model and a 2-D axisymmetric conical model. In both models, peristaltic motion is induced by a traveling wave along the wall of the computational domain which deforms the wall and the computational mesh. These geometrical models are coupled with a finite volume solver from the open source software package OpenFOAM which is used to simulate the peristaltic flow for different Newtonian and non-Newtonian fluids in the laboratory (or Eulerian) frame of reference. After validation of the solver with experimental data, simulations are performed in each geometrical model to determine the influence of a given set of parameters on peristaltic flow behavior and transport efficiency. The parameters that are varied include the wave speed, relative occlusion, Newtonian viscosity, and power-law index for shear-thinning non- Newtonian fluids. For both computational models, the transport efficiency is found to increase strongly with relative occlusion, to decrease as the amount of shear-thinning increases, and to be independent of wave speed. In the tubular model, transport efficiency is found to be independent of Newtonian viscosity, while in the conical model, it decreases as viscosity decreases for Reynolds numbers greater than one.

Cite this publication as follows:
Alokaily S, Feigl K, Tanner FX, Windhab EJ: Numerical Simulations of the Transport of Newtonian and Non-Newtonian Fluids via Peristaltic Motion, Appl. Rheol. 28 (2018) 32832.

The oscillatory shear rheological behaviors of a polyolefin plastomer (POP) at various temperatures were examined within its linear viscoelastic (LVE) regime. The apparent storage modulus, loss modulus, complex modulus, complex viscosity, and phase angle of POP at various temperatures are all found gap dependent, revealing that wall slip occurred under the applied oscillatory shear with the shear stress amplitude controlled constant. All Han plots and van Gurp-Palmen (vGP) plots of POP samples overlapped each other at various gaps at a certain temperature, suggesting that a time-gap-superposition (TGS) is valid with all the apparent angular frequency dependent storage modulus and loss modulus of POP at various gaps shifted to their master curves at a selected reference gap. This indicates that the wall slip can be understood as adding a dashpot in series to POP sample only with the apparent relaxation time multiplied by a shift factor. By TGS, a method to determine the wall slip length b and the actual oscillatory shear rheology of the fluids was consequently established. The results showed that the obtained b is dependent on temperature and wall slip made it possible to extend the experimental angular frequency range to lower frequencies. Further analysis revealed that wall slip did not influence the Arrhenius viscosity dependence of POP on temperature, while the viscous flow activation energy decreased.

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Li J, Wang L, Yu D, Christiansen JdC, Jiang S: Wall Slip of Polyolefin Plastomers under Oscillatory Shear, Appl. Rheol. 28 (2018) 33226.

In petroleum drilling, aqueous Polyanionic Cellulose solutions (PAC) are often used as a drilling fluid model system in experimental laboratory studies to investigate cuttings transport. Cuttings transport refers to the transportation of drilled-off solids out of the wellbore. In these studies, PAC solutions are typically assumed to behave purely viscous, i.e. they do not show timedependent/ thixotropic and/or viscoelastic properties. In this study, a rheological characterization of PAC has been performed in combination with an evaluation of time scales characterizing the fluid to verify the conventional assumption of a purelyviscous fluid. It is found that PAC solutions are generally not purely viscous: They feature viscoelastic behavior on time scales of the order of 0.01 to 1 s, such as normal stress differences, as well as thixotropic behavior on larger time scales of the order of 10 to 1000 s because of their polymeric microstructure. If simplified to a purely viscous fluid, the degree of uncertainty in representing the measured apparent shear viscosity may increase by an order of . 75 to 90 % depending on the relevant time scale. When obtaining flow curves, a sufficiently long measurement point duration (sampling time for a particular torque reading) is required to ensure that the liquid microstructure has reached its dynamic equilibrium at the desired shear rate. Due to their polymeric nature, PAC solutions feature Newtonian viscosity plateaus at both low and high shear rates. For modeling purposes, the application of a Cross/Carreau material function is recommended because it both best describes the flow curve data and minimizes extrapolation errors compared to the conventionally used Power Law material function.

Cite this publication as follows:
Busch A, Myrseth V, Skjetne P, Khatibi M, Johansen ST: Rheological characterization of polyanionic cellulose solutions with application to drilling fluids and cuttings transport modeling, Appl. Rheol. 28 (2018) 25154.

A triple pressure-stage capillary rheometer was individually developed for providing an insight of pressure effect on polymeric melts viscosity during steady and continuous flow. Three capillary dies with identical/varied diameters and aspect ratio were assembled in series along the flow direction, relying on which the flow was divided into three zones with varied pressures under the same flow rate. Several polymeric melts, such as low density polyethylene (LDPE), polystyrene (PS), polypropylene (PP) as well as its nanocomposites of PP/CaCO3, PP/Mg(OH)2, and PP/ halloysite nanotubes (PP/HNTs) were taken as the experimental samples. The principles for calculating the pressure sensitivity of shear viscosity in capillary flow were discussed, including methods based on constant shear rate (CSR), constant shear stress (CSS), and curve superposition (CSP). For the several polymer melts adopted in this work, a sequence of pressure dependence of viscosity was revealed as PS > PP > LDPE, which is typically acknowledged.

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Lin X, Liu J, Wu C, Wu M, Ren D, Zhang J: Experimental evaluation of the pressure sensitivity of molten polymer viscosity with a triple-stage capillary rheometer, Appl. Rheol. 28 (2018) 25503.

A novel method is introduced to describe quantitatively hysteresis seen in flow curves of microfibrillated cellulose suspensions. Also, a data normalisation procedure is presented that allows a direct comparison of data from suspensions of different solids contents. The discussion of the flow curve hysteresis of an MFC suspension is proposed to provide a lot of information on the suspension morphology under flow. Such information is not only useful for process design, but also may serve as a quality control tool. Hysteresis data as a function of the suspension solids content are provided, and considered with reference to an overview made of peer work in the field. Two discrete hysteresis loop areas were found in the flow curves presented in this work, each associated with a distinct shear rate region, one where the viscosity of the flow curve during shear rate increase is higher than that of the shear rate flow curve at decreasing shear rate (named positive hysteresis) and another where it is the opposite (named negative hysteresis). This behavior seems to have been rarely reported, and where reported we offer an explanation, based on morphological models and rheometer measurement set up, as to why other researchers may find a variety of hysteresis forms. It is hypothesised that the negative normalised hysteresis is mainly depending on the excessive flocculation/ structuration induced at intermediate shear rates during the shear rate increase, and that it is necessarily less with increasing solids content because of the reduced availability of free water. The positive normalised hysteresis, however, is considered to originate from the different morphologies at lower shear rates, i.e. the initial, homogeneous structure vs. the structure that was previously induced by the intermediate shear during shear rate decrease. The positive normalised hysteresis appears not to depend on the solids content, indicating a self-similarity or scaling behavior of the structuring with respect to the underlying network structure.

Cite this publication as follows:
Schenker M, Schoelkopf J, Gane P, Mangin P: Quantification of flow curve hysteresis data . a novel tool for characterising microfibrillated cellulose (MFC) suspensions, Appl. Rheol. 28 (2018) 22945.

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SohelMurshed SM, NietodeCastro C, EnriqueJulia J: First European Symposium on Nanofluids (ESNf2017), Appl. Rheol. 28 (2018) 45.

Concentrated suspensions are very complex in nature and exhibit non-Newtonian flow properties although the suspending fluid might behave as a Newtonian fluid. Among the interesting properties, wall slip will be the main focus of this study. The formation of wall slip layer adJacent to the solid boundary may lead to inaccurate measurement of rheological properties. So, the measured viscosity can be lower than the actual viscosity and thus a basic understanding on wall slip is critical. Concentration, particle size, and temperature are the factors affecting the wall slip mechanism. Therefore, this research study tends to study the relationship between the parameters (concentration, particle size, and temperature) and wall slip. The result shows that the slip velocity increases with shear stress under the conditions where (i) concentration decreases, (ii) particle size increases, and (iii) temperature increases. Two regression models considering the three parameters are proposed and can be used respectively as an alternative to predict slip velocity and true shear rate.

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Chin RJ, Lai SH, Ibrahim S, WanJaafar WZ: Factors affect wall slip: particle size, concentration and temperature, Appl. Rheol. 28 (2018) 15775.

The performance of modern slurry dewatering equipment is essentially dependent on the efficiency of compression. Shear yield stress as an index of flowability and compressibility is affected by suspension properties, while the presence of reagents may be significant. In this work, the effect of fine fraction, pH, flocculant, and collector concentration on the shear yield stress of copper flotation tailings at concentrators placed at Sarcheshmeh and Shahrebabak (Iran) were examined. Slump and settling tests were utilized to investigate the shear yield stress and compressibility of suspension. A pilot scale column was also employed to investigate the compressibility of suspension. Results indicated that shear yield stress increase, while compressibility decrease with flocculant concentration and fine fraction. It was found that the shear yield stress steadily increased with pH. Furthermore, in the presence of collectors the shear yield stress was reduced, while the compressibility enhanced.

Cite this publication as follows:
Garmsiri MR, HajiAminShirazi H: The effect of suspension properties on shear yield stress and compressibility of the suspension of copper flotation tailings, Appl. Rheol. 28 (2018) 15721.

White Portland cement can be used such as decorative coatings, masonry regularization as the skin coat, and many other applications mainly due to the ease of association with pigments to confer coloring to the applied products for aesthetic purposes. Despite of the evaluation of the hardened stage properties to be more commonly found in literature, Just a few published works monitored the transition from fluid-to-solid stage, but this is an important step because it defines the performance of products over time. The main purpose of this work was to compare the consolidation of different types of white Portland cement during the hardening stage, i.e. using a combined evaluation of the chemical and physical phenomena. Isothermal conduction calorimetry was the method used to monitor the heat release during the hydration reaction and oscillatory and compressive rheometry were applied to monitor the changes in workability over time. The setting time, measured by Vicat test represents the open time of each composition and was evaluated because it is affected by the physicochemical changes of the cement. Despite the obtained results are standardized, they are empirical/arbitrary by nature. Three brands of white Portland cements (CauêAalborg, and Tolteca) were chosen and their suspensions were prepared to achieve a constant watercement ratio of 0.5. All suspensions presented shear thinning behavior, but different levels of yield stress and apparent viscosity. The Tolteca cement presented the fastest heat release, which impacted the gain on consistency as measured by oscillatory rheometry or the loss of workability as measured by the squeeze flow test. The combined evaluations, i.e. physical and chemical results indicated that despite the fact that the changes during the hardening process had been affected: Correlations were only observed in the physical parameters indicating that the hydration reaction promotes random changes in the microstructure development.

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Carbone CE, Romano RCdO, Cincotto MA, Pileggi RG: Hardening stage evaluation of white Portland cements using oscillatory and compressive rheometry, isothermal calorimetry and the Vicat test, Appl. Rheol. 28 (2018) 16396.

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HernandezLucas MJ, SanzTaberner T, SalvadorAlcaraz A, RubioHernandez FJ, Steinbruggen R: IBEREO 2017, Appl. Rheol. 27 (2017) 42.

Bacterial cultures, when under appropriate conditions, will grow into a biofilm. This weak hydrogel, composed of a complex conglomeration of bacterial clusters and extrapolymeric substances, serves to protect and insulate the bacteria from mechanical disturbances and environmental perturbations that may include antibiotics. Measuring the bulk rheology of the biofilm provides a quantitative description of the macroscopic structural integrity of the soft solid, which can be used to evaluate the efficacy of techniques that are often directed at their removal or prevention. Techniques for measuring the rheology of biofilms vary significantly, ranging from filtering or scraping the biofilm from its growth medium to attempting to grow the biofilm directly on the geometry of the rheometer. In this study, we developed a protocol for measuring the bulk rheology of a biofilm that was grown in a liquid medium. By keeping the biofilm intact from its growth phase through its rheological measurement, this method allows the mechanical strength of the biofilm to be probed without compromising its integrity. Presented in the form of case studies, the results from this study confirmed the gel-like structure of the biofilm of the wild-type strain of Pseudomonas aeruginosa (PAO1). The flexibility of this protocol was shown by varying the incubation time of the biofilm from 4 to 9 days, providing a bulk elastic modulus that varied over two orders of magnitude and a yield stress that varied by an order of magnitude. Finally, in an attempt to demonstrate the fragility of biofilm, measurements were also taken on samples that were simply transferred from their incubated Petri dish to the rheometer. Results from the mechanical robustness of the biofilm are highlighted to emphasize the importance of understanding and addressing the mechanical strength of the biofilm system before attempting to remove the bacterial contamination through chemical or mechanical means.

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Daalkhaijav U, Walker TW: Developing a Nondestructive Technique for Measuring Bulk Rheology of Pseudomonas Aeruginosa Biofilm, Appl. Rheol. 27 (2017) 64033.

A challenge for underground CO2 storage is the leakage of the buoyant supercritical gas through microcracks in wellbores that cannot be sealed with current oilfield cements that are too viscous and cannot penetrate the cracks. Polymer gels consisting of pH-sensitive hydrogel particles suspended in an aqueous solution offer a potential alternative. The rheology of aqueous solutions of Carbopol 934 as a model pH-sensitive gel is measured to find the compositions and pHs for both ease of inJection and to seal cracks against the flow of bulk CO2 and CO2 dissolved in brine. The polymer gels have low viscosity at low pH and can easily flow into the microcracks. In the elevated pH of the microcracks, the particles swell creating a significant yield stress sufficient to seal leakage pathways. The yield stress reaches a maximum at pH 5 and it increases with increasing concentration. The flow curves of stress versus shear rate for all pHs and concentrations are well-described by the Herschel-Bulkley model with an exponent of about 0.34 except for highly acidic conditions when the gelant solutions show a much lower yield stresses and higher exponents. The flow curves can be collapsed onto a single universal flow curve rescaled with the yield stress, the low frequency shear modulus and the suspending fluid viscosity. The presence of salts, especially high valence salts, reduce the yield stress of the gels considerably. It is shown that the addition of chelating agents mitigates this effect and can restore more than 30% of the yield stress of the gelant.

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Shafiei M, Bryant S, Balhoff M, Huh C, Bonnecaze RT: Hydrogel Formulation for Sealing Cracked Wellbores for CO2 Storage , Appl. Rheol. 27 (2017) 64433.

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Galindo-Rosales FJ: 1st Summer School on Complex Fluid-Flows in Microfluidics (2017) , Appl. Rheol. 27 (2017) 46.

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Svensek D: 10th Liquid Matter Conference (Liquids 2017), Appl. Rheol. 27 (2017) 48.

Hydrogels are cross-linked polymer networks which are water-insoluble. They are suitable for several technical and biomedical applications due to the ability of some gels to swell and deswell as reaction to external stimuli. Such gels are synthesized and shift from a fluid-like liquid with solved components towards the final polymeric network with gel-like properties. Monitoring and characterizing this process is fundamental on the one hand to understand the chemical and physical behavior and on the other hand to adopt the application and production of such gels. Therefore, this investigation focuses on the characterization of the gelation of a nanocomposite hydrogel system based on PNIPAm with and without mechanical loads applied, using rheology. Measurements are conducted featuring rotational and oscillating rheometry and the results found are compared and evaluated. Furthermore the impact of a strong pre-shear, preventing the gelation, prior to the actual gelation, is investigated. The results found show a strong influence of the applied load as well as of an applied pre-shear on the gelation and furthermore on the mechanical properties of the final hydrogels. Therefore those parameters be taken into account for future investigations as well as for the large scale productions of hydrogels.

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Nowak J, Barhold C, Kessler C, Odenbach S: Gelation of a Nanocomposite-Hydrogel system and its dependency on mechanical loads, Appl. Rheol. 27 (2017) 52850.

The Couette flow of a model yield-stress fluid with slip at the walls, a 0.12% Carbopol® 940 microgel, was analyzed in this work by simultaneous rheometrical and particle image velocimetry measurements (Rheo-PIV). The Rheo-PIV technique was first tested in the analysis of the Couette flow of a Newtonian fluid and then used to determine the velocity and shear rate distributions of the microgel across gap. A reliable and full description of the different flow regimes occurring in the steady Couette flow of yield-stress fluids with slip at the rheometer walls was obtained, which includes rigid body-like motion at stresses below the yield one, rigid body-like motion and shear flow at stresses above the yield one, as well as pure shear flow once the shear stress at the outer cylinder overcomes the yield value. Slip occurred at both cylinders, which were made up of hydrophobic (inner) and hydrophilic (outer) materials, respectively. The slip velocity values measured at both walls increased along with the shear stress and the trends of these dependencies deviated from the predictions of the hydrodynamic and elastohydrodynamic lubrication mechanisms of slip in the flow of soft deformable particle dispersions [1]. Besides, the yield stress was determined with good accuracy from the velocity profiles, as well as the location of the yielded and non-yielded regions for each flow condition. Finally, the consistency of the obtained velocity profiles was tested by comparison with a theoretical prediction for the Couette flow problem of a Herschel-Bulkley fluid without slip.

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Medina-Banuelos EF, Marin-Santibanez BM, Perez-Gonzalez J, Rodriguez-Gonzales F: Couette flow of a yield-stress fluid with slip as studied by Rheo-PIV, Appl. Rheol. 27 (2017) 53893.

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Iyer BVS, Dixit H: Complex Fluids Meeting (CompFlu@Hyd 2016), Appl. Rheol. 27 (2017) 45.

This study compared the flow curve fitting and oscillatory strain sweep methods to determine the yield stresses of Portland cement mortars using a ball measuring system (BMS). The tests were performed in two stages. In the first stage, the responses from a BMS with ball diameters of 8, 12, and 15 mm were compared to those from conventional cone-plate geometry with two different polymer dispersions. In the second stage, thirty-five mortars were prepared with 10 wt% of the cement replaced by silica fume. Five water-to-binder ratios and seven concentrations of a polycarboxylate-based superplasticizer were selected. An 8-mm diameter ball was selected for use in mortar production due to the smaller drag that it produced. The results indicated an increase in the linear viscoelastic region due to a reduction in the water-to-binder ratio and/or an increase in the superplasticizer concentration. In oscillatory tests, the dynamic yield stress was related to the stability of the cement paste and the strengths of the internal links between the cement particles. The flow and Herschel-Bulkley yield stresses result were not statistically different. Therefore, flow stress calculations could be carried out using either of these methods. An amplitude sweep test performed using the BMS may be an alternative method of studying the rheology of cement-based materials.

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Leon-Martinez FM, Cano-Barrita PFdJ: Yield stress of mortars in rotational and oscillatory shear experiments usinag a ball measuring system, Appl. Rheol. 27 (2017) 45838.

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Campo-Deano, Araujo N, Pagonabarraga I, Toschi F: Flowing Matter 2017, Appl. Rheol. 27 (2017) 47.

The hardening of cement pastes occurs due to coagulation/flocculation promoted by the hydration reactions. At this way, depending on the physico-chemical characteristics of the powder, different changes are obtained during the microstructure formation. Thus, as the use of supplementary cementitious materials is rising worldwide, this stage of construction process is being more complex. So, this work was conducted to evaluate the hardening phenomenon of pastes formulated with Portland cements blended with limestone filler (LF) and ground blast furnace slag (BFS). Vicat test, oscillatory rheometry and isothermal conduction calorimetry were used to monitor this transition. Vicat test results indicate different setting times as a function of addition, but no information before these times was obtained. Using isothermal calorimetry was possible to monitor the related changes to the chemical reactions since the first contact with water, and using rheometry, the rate and force of cement particle agglomeration. During the discussion of results will be not presented in depth the results of the three methods, but will be shown that they are complementary and provide a better explanation to the transition from fluid-to-solid behavior, independently of kind of supplementary cementitious materials.

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Romano RCdO, Maciel MH, Pileggi RG, Cincotto MA: Monitoring of hardening of Portland cement suspensions by Vicat test, oscillatory rheometry and isothermal calorimetry, Appl. Rheol. 27 (2017) 36006.

It has been proposed that hydrogen bonding plays a role in promoting the electrospinnability of some materials. In this work, the significance of non-covalent interactions in the electrospinnability of aqueous sugar solutions (i.e. mono- and disaccharide) was investigated as a function of carbohydrate concentration. The electrospinnability of concentrated aqueous solutions of glucose, fructose, and sucrose was studied by physicochemical and rheological characterization methods, and by subsequently examining the resulting morphology via scanning electron microscopy. The results on the electrospinning of concentrated saccharide solutions indicated the significance of non-covalent interactions on the electrospinning of these systems. Electrospinnability models based on critical concentration and visco-elasto capillary theories were compared with the experimental results. It is shown that visco-elasto capillary theory has the closest correlation with the experimental data. The electrospinnability of highly concentrated saccharide solutions appears to be directly related to the density and intermolecular bonding capacity of the solution.

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Lepe PGT, Tucker N, Watson AJA, LeCorre-Bordes D, Fairbanks AJ, Staiger MP: The electrospinnability of visco-elastic sugar solutions, Appl. Rheol. 27 (2017) 35703.

Limited information exists in literature regarding the effect of styrene-butadiene rubber (SBR) latexes on rheology and stability of lightweight self-consolidating concrete (LWSCC) intended for repair and precast works. Four series of LWSCC mixtures prepared with various lightweight aggregate (LWA) and SBR concentrations were considered in this proJect: The free water was adJusted to secure compressive strength of 40 ± 3.5 MPa. The slump flow remained fixed at 700 ± 25 mm, while unit weight varied from 1790 to 2280 kg/m3. Test results have shown that SBR additions lead to reduced concrete flow rate and passing ability. However, improved static stability such as bleeding, segregation, and floating of LWA. The rheological properties including yield stress and plastic viscosity increased for higher SBR additions, reflecting increased cohesiveness resulting from coalescence of water-soluble latexes and binding of cementitious matrix. Three categories of LWSCC classes specified in the European Guidelines were proposed with respect to rheological properties. A Ψ-factor was developed along with series of regression models to predict the combined effect of free water, viscosity-modifier, LWA, and SBR on rheology and stability of polymermodified LWSCC.

Cite this publication as follows:
Assaad J: Rheology and stability of lightweight polymer-modified self-consolidating concrete , Appl. Rheol. 27 (2017) 25807.

The overall obJective of this work was to explore the rheology of an advanced performance xanthan gum, which is able to endure the shear and turbulent flows typically found in high-shear mixers or even homogenizers. A further goal was the development of a rheological experimental setup that can be used to gain information about the structural recovery after applying a given shear stress. A fast structural recovery after cessation of shear is essential for a wide range of practical applications. The high zero shear viscosity, strong shear thinning response along with a fast drop of viscosity with shear time and structural recovery support the applications of this xanthan gum as thickening agent and stabilizer. The rheological characterization focused on the influence of xanthan gum concentration (0.15 – 0.40%(m/m)) on the dynamic viscoelastic properties, steady shear and thixotropic behavior, and kinetics of structural recovery.

Cite this publication as follows:
Carmona JA, Calero N, Ramirez P, Munoz J: Rheology and structural recovery kinetics of an advanced performance xanthan gum with industrial application, Appl. Rheol. 27 (2017) 25555.

This paper presents an experimental study on the rheological properties of heavy crude oil containing sand to determine the effects of sand size distribution and mass concentration on apparent viscosity, thixotropic behavior, yield stress and viscoelastic properties. The results of these analyses demonstrate that heavy crude oil containing sand shows strong shear-thinning behavior and a certain degree of thixotropic properties. After blending heavy crude oil with sand, the apparent viscosity and the area of the thixotropic loop first decrease and then steadily increase with increasing sand mass concentration. At a fixed mass concentration, apparent viscosity appears to increase with increasing particle size, while yield stress decreases. Moreover, adding sand generally enhances the elastic modulus of heavy crude oil, while the complex viscosity remains slightly less than the apparent viscosity. These results provide new information helpful for removing sand from heavy crude oil.

Cite this publication as follows:
Zhang D, Liu S, Xu j: Rheological properties of heavy crude oil containing sand from Bo-hai oilfield in China, Appl. Rheol. 27 (2017) 24849.

This paper investigates the influence of limestone crushed sand dust (LCSD) on rheological properties of cement mortar based on crushed sand (CS) with different mineralogical nature (limestone and siliceous). A LCSD with a specific surface BET of 1470 m2/kg was used at different content replacement by mass of sand (0, 5, 10, 15, and 20 %). The water-cement ratio (W/C) and the cement content were kept constant for all mixes. The results show that the slump decreased as well as the flow time, the yield stress and the viscosity of mortar increased with the increase in LCSD content. Thus, the mortar based on limestone crushed sand (LS) has a low loss of rheological properties compared with a mortar based on siliceous crushed sand (SS). Yet, for 0 % of LCSD, it was found that the rheological properties are nearly equal for both CSs. The use of superplasticizer (Sp) significantly improves the workability and rheological properties. However, the rheological behavior of mortar has been strongly affected by increasing the volume concentration of CS whereas the effect of CS on fresh mortar presents significantly greater disadvantages compared with rolled sand (RS).

Cite this publication as follows:
Safiddine S, Debieb F, Kadri E, Menadi B, Soualhi H: Effect of crushed sand and limestone crushed sand dust on the rheology of cement mortar, Appl. Rheol. 27 (2017) 14490.

In modern intensive care a comprehensive solution for monitoring the coagulation status or blood clotting problems is currently not available, because fast reliable detection of all bleeding-based disorders (coagulation, fibrinolysis, platelet function) cannot be conducted with a single medical device. This situation calls for a comprehensive technical solution, which we think possible to be solved with a rheological piezo-based system. Rheological measurements provide valuable information on the viscoelastic properties of complex fluids. Here, we compared the performance of a commercially available rheological industrial device using shear stress (Kinexus Pro, Malvern) with that of a piezo-based research measuring system (piezoelectric axial vibrator, PAV) applying squeeze flow to sample fluids. Comparative measurements using different xanthan concentrations (0.1 to 5%) were carried out at 25 and 37 °C. At higher concentrations (1, 2, and 5%), there was an overlapping frequency range and a consistent range of the viscous and elastic shear viscosity for both systems, allowing direct comparisons. Specifically the lower concentrations of 0.1, 0.2, and 0.5% xanthan could be used to assess the possibility of both systems to measure blood coagulation, as those concentrations correspond approximately to the viscosity of human blood. Measurement of blood coagulation was then also tested with the PAV. Measurement repeatability was assessed performing blood coagulation measurements over time at different frequencies (10, 100, 300, and 1000 Hz). The middle frequencies of 100 and 300 Hz provided the most repeatable results for blood. Afterwards the activated clotting time (ACT) was performed with PAV at 300 Hz. The piezo-based measuring system was able to differentiate between various heparin blood concentrations (1, 2, and 3 IU/ml). In this study the reliability, repeatability and limitations of the piezo system were examined. Our initial results showed that the piezo system can be used to assess blood coagulation, but further studies are necessary to confirm these promising results. The aim of a fast, small and reliable point-of-care system may be possible with this type of rheological device.

Cite this publication as follows:
Kunnkattu S, Gross T, Stoppelkamp S, Knieps J, Remmler T, Fennrich S, Wendel HP, Rauch N: Potential of a piezo-based measuring method (PAV) as a haemostasis monitoring system compared to a rotational rheometer , Appl. Rheol. 27 (2017) 13540.

We study the effect of wall slip on the measured values of the yield stress of magnetorheological (MR) fluids. For this aim we used a rheometer provided with parallel-plate geometries of two types, distinguished by having smooth or rough surfaces. We found that wall slip led to the underestimation of the yield stress when measuring geometries with smooth surfaces were used, and that this underestimation was more pronounced for the static than for the dynamic yield stress. Furthermore, we analysed the effect that both irreversible particle aggregation due to colloidal interactions and reversible magnetic fieldinduced particle aggregation had on the underestimation provoked by wall slip. We found that the higher the degree of aggregation the stronger the underestimation of the yield stress. At low intensity of the applied magnetic field irreversible particle aggregation was dominant and, thus, the underestimation of the yield stress was almost negligible for well-dispersed MR fluids, whereas it was rather pronounced for MR fluids suffering from irreversible aggregation. As the magnetic field was increased the underestimation of the yield stress became significant even for the best dispersed MR fluid.

Cite this publication as follows:
Caballero-Hernandez J, Gomez-Ramirez A, Duran JD, Gonzalez-Caballero F, Zubarev A, Lopez-Lopez MT: On the effect of wall slip on the determination of the yield stress of magnetorheological fluids, Appl. Rheol. 27 (2017) 15001.

Cite this publication as follows:
Kontopoulou M, Heuzey M, Mighri F: Symposium on Rheology of Complex Fluids and Honorary Symposium for Pierre Carreau during the 66th Canadian Chemical Engineering Conference, Appl. Rheol. 26 (2016) 53.

Dispersion quality has a large influence on the resulting properties of filled polymers, hybrids and nanocomposites in general. Reducing the van der Waals forces and therefore, matching the refractive index between the filler and the matrix should improve dispersion in hybrid materials. However, in this case the usual light-based techniques cannot be used to assess dispersion quality. In this work, dispersions containing silica nanoparticles and a solvent mixture of 1-butanol and benzyl alcohol were analysed by rheological methods. The refractive index of the solvent was changed by varying the mixing ratio, and thus the effect of index difference on the filler-matrix interaction was investigated. In agreement with theory, a stronger gel network was observed when the refractive index of filler and solvent were matched. If the difference in refractive index of the two materials became too large, particles and solvent interaction was reduced, and agglomerates were formed. This resulted in a weaker gel network.

Cite this publication as follows:
Frohlich KA, Mitrentsis E, Clemens F, Hoffmann B, Michaud V, Graule T: Assessment of the Dispersion Quality of refractive index-matched nanodispersions, Appl. Rheol. 26 (2016) 65050.

The shape and fracture of the free surface frequently limits the measuring range and impedes the use of optical velocimetric techniques in parallel plate and cone plate setups. To prevent this, various kinds of edge guards are often employed. In the present study, we elucidate how an edge guard distorts the steady velocity profile in a parallel plate setup. To this end, we analyzed the velocity field of a strongly shear-thinning fluid, a Newtonian fluid and a set of suspensions via particle image velocimetry in a parallel plate device. Several guard ring sizes were studied. The distortion is described by a simple three parameter model. These parameters are mostly constant for different fluids and suspensions with particle volume fractions below 45%. With increasing radius, the guard ring.s influence approaches a limiting value that we attribute to the influence of the fluid surrounding the gap. Our results indicate a limiting ratio of the difference between plate radius and guard to gap size that should always be exceeded. In the presence of a guard ring, even Newtonian fluids do not exhibit a constant shear rate for most radial distances within the gap. This distortion of the velocity field challenges the simple superposition approach of unguarded device and guard influence that is prevalent in the literature.

Cite this publication as follows:
Pieper S, Schmid H: Guard ring induced distortion of the steady velocity profile in a parallel plate rheometer , Appl. Rheol. 26 (2016) 64533.

Cite this publication as follows:
Masubuchi Y: The XVIIth International Congress on Rheology (ICR 2016), Appl. Rheol. 26 (2016) 52.

Cite this publication as follows:
Duenweg B, Prakash JR: Hydrodynamic Fluctuations in Soft-Matter Simulations, Appl. Rheol. 26 (2016) 51.

By following the path of a liquid bolus, from the oral preparatory phase to the esophagus, we show that a few fundamental concepts of fluid mechanics can be used to better understand and assess the importance of bolus viscosity during human swallowing, especially when considering dysfunctional swallowing (dysphagia) and how it can be mitigated. In particular, we highlight the important distinction between different flow regimes (i.e. viscosity controlled versus. inertia controlled flow). We also illustrate the difference between understanding bolus movements controlled by a constant force (or pressure) and those controlled by a constant displacement (or velocity). We limit our discussion to simple, Newtonian liquids where the viscosity does not depend on the speed of flow. Consideration of non-Newtonian effects (such as shear thinning or viscoelasticity), which we believe play an important part in human swallowing, requires a sound grasp of the fundamentals discussed here and warrants further consideration in its own right.

Cite this publication as follows:
Burbidge AS, Cichero JAY, Engmann J, Steele CM: ''A day in the life of the fluid bolus'': An introduction to fluid mechanics of the oropharyngeal phase of swallowing with particular focus on dysphagia., Appl. Rheol. 26 (2016) 64525.

While shear thickening is a well-known feature of some polymer solutions, its observation in the absence of a clear specific chemical or structural mechanism and at very low rates of shear (shear rate ≤ 0.1/s) in our own data, as well as in several polymer systems in the literature, has prompted further investigation. Using the rheologically-reproducible and commercially available dysphagia product ResourceÒ Thicken Up Clear (produced by Nestle Health Science) as a canonical demonstration fluid, we show that the observation of a local maximum in the steady shear viscosity at very low shear rates can be completely attributed to the sample not having reached steady state conditions, and correspondingly, to the measurement not having been performed in steady simple shear flow. We propose two criteria to ensure equilibration during steady state flow rheological measurements: a substantial increase in the measurement time allotted for each point such that the total material strain accumulated in the sample is allowed to reach shear strain ≤ 5 and/or a stricter convergence criterion of 10 consecutive readings within a tolerance of 1%.

Cite this publication as follows:
Wagner CE, Barbati AC, Engmann J, Burbidge AS, McKinley GH: Apparent shear thickening at low shear rates in polymer solutions can be an artifact of non-equilibration, Appl. Rheol. 26 (2016) 54091.

The main obJectives of this paper are to (i) study the rutting performance of asphalt binders modified with styrene butadiene rubber (SBR) copolymer, polyphosphoric acid (PPA) and SBR+PPA, (ii) quantify the percent recoveries R and the nonrecoverable compliances Jnr in the multiple stress creep and recovery (MSCR) test, and (iii) indicate the best formulations in terms of rutting performance. All these formulations have the same high-temperature performance grade in the Superpave® specification (PG 76-xx). The Burgers model was used to fit the laboratory data and the parameter GVwas obtained from the model. The degrees of improvement in the R and the Jnr values after binder modification are higher for the AC+SBR+PPA and the AC+PPA than for the AC+SBR and the results are slightly better for the AC+SBR+PPA. The use of longer creep and recovery times led to increases in the stress sensitivity of the modified asphalt binders and in their rutting potential (higher Jnr values and lower R values) and these effects are more pronounced for the AC+SBR. The AC+SBR+PPA was identified as the best formulation in terms of elastic response and susceptibility to rutting, followed by the AC+PPA and the AC+SBR.

Cite this publication as follows:
InocenteDomingos MD, Faxina AL: High-temperature properties and modeling of asphalt binders modified with SBR copolymer and PPA in the multiple stress creep and recovery (MSCR) test, Appl. Rheol. 26 (2016) 53830.

During mixing of wheat flour doughs, the distribution of the gluten network changes as a result of continuously applied large deformations. Especially gliadin, changes its distribution in the whole network during mixing. It is possible to fundamentally explain the role of molecular changes in more detail using large amplitude oscillatory measurements (LAOS) in the non-linear region. Therefore, the purpose of this study is to understand the effect of mixing on the non-linear fundamental rheological behavior of soft wheat flour dough using LAOS. Dough samples were obtained at 4 different phases of the Farinograph mixing and LAOS tests were done on each of them. LAOS tets give in depth intracycle understanding of rheology. All samples showed strain stiffening S and shear thinning T behavior at large strains previously not known in the cereal rheology community. Increasing mixing time (phase 1 to phase 4) and decreasing frequency resulted in retardation in the break of strain stiffening as strain increases. The strain stiffening behavior started to decrease for the dough samples at the 3rd and the 4th phases of mixing. LAOS data enabled us to describe the non-linear rheological changes occurring both in the viscous part largely attributed to the starch matrix and elastic part largely attributed to the gluten network components of the soft wheat flour dough under large deformations.

Cite this publication as follows:
Yazar G, Duvarci O, Tavman S, Kokini JL: Non-Linear Rheological Properties of Soft Wheat Flour Dough at Different Stages of Farinograph Mixing, Appl. Rheol. 26 (2016) 52508.

This work presents a simple, scalar model for predicting a nonlinear shear stress response of a viscoelastic fluid in Large Amplitude Oscillatory Shear (LAOS) experiments. The model is constructed by replacing the viscosity in the well-known Maxwell model by a shear rate dependent viscosity function. By assuming the empirical Cox-Merz rule to be valid, this shear rate dependent viscosity function is specified based on the Maxwell expression for the complex viscosity. We thus construct a particular case of the White-Metzner constitutive equation. Numerical solutions as well as an asymptotic analytical solution of the model are presented. The results, analyzed for higher harmonic content by Fourier transform, are compared to experimental data of a viscoelastic solution of wormlike micelles based on cetyltrimethylammonium bromide. Good agreement is found for low frequencies, where viscous properties dominate.

Cite this publication as follows:
Merger D, Abbasi M, Merger J, Giacomin AJ, Saengow C, Wilhelm M: Simple Scalar Model and Analysis for Large Amplitude Oscillatory Shear, Appl. Rheol. 26 (2016) 53809.

Cite this publication as follows:
Cheneler D: Glassy Metals (K. Russew and L. Stojanova), Appl. Rheol. 26 (2016) 8.

Self-consolidating concrete (SCC) is very sensitive to delays or stoppages between successive lifts during casting, especially given that vibration is prohibited with this highly flowable type of concrete. The investigation reported in this paper seeks to quantify the effect of mixture proportioning on thixotropy along with the resulting effect on interfacial bond strength of hardened material that could result from successive lifts. The suitability of the equivalent mortar phase to simplify testing protocols and appropriately predict SCC properties was given particular attention; the concrete-equivalent-mortar (CEM) mixtures are derived from SCC by eliminating the coarse aggregate fraction and replacing it by an equivalent quantity of sand having equal surface area. Tests results have shown that SCC and CEM mixtures prepared with combinations of increased cement content, silica fume, and/or viscosity-modifier led to higher levels of thixotropy. Yet, the responses determined using SCC were higher by around 1.6 times than those of CEM, given the differences in unit weight and air content between both materials. Good correlations are established between thixotropy and interfacial bond strengths of SCC and CEM mixtures. Key words:

Cite this publication as follows:
Assaad J, Daou Y: Use of the equivalent mortar phase to assess thixotropy of fresh SCC - Prediction of interfacial bond strength between successive placement lifts, Appl. Rheol. 26 (2016) 42759.

This paper describes the effects of irradiation on the rheological and electrical properties of a 7.7% mass fraction of native bovine collagen in water. The radiation dose was in the range of 0-500 Gy. Rheological oscillation measurements were done at temperatures of 10, 20, and 30 C. There was a statistically significant dependency of storage and loss moduli on irradiation dose and oscillation frequency. There was no significant change in the electrical conductivity of collagen during oscillation movements or any dependence on irradiation dose.

Cite this publication as follows:
Landfeld A, Houska M, Skocilas J, Zitny R, Novotna P, Stancl J, Dostal M, Chvatil D: The effect of irradiation on rheological and electrical properties of collagen matter, Appl. Rheol. 26 (2016) 43775.

Former studies show that the coarse particle plays a very important role in the determination of the yield stress of fluid-solid mixtures such as debris flows. The characteristics of the coarse particle in these mixtures include particle size, gradation, shape, and type of material. To assess the influence of these coarse particles on the yield stress the concept of equivalent volumetric solid concentration C is introduced. The equivalent concentration can be derived from the volumetric solid concentration by considering the particle size, gradation, shape, and type of material. Laboratory experiments to determine the yield stress of various mixtures were conducted to calibrate the coefficients of these coarse particle characteristics. A yield stress phenomenological expression is proposed using the refined volumetric solid concentration (equivalent concentration), which could be calibrated by the experiments in this study. The validation of this phenomenological expression with data from literature shows good agreements, especially for higher volumetric concentrations of the sediments.

Cite this publication as follows:
Yu B, Chen Y, Liu Q: Experimental study on the influence of coarse particle on the yield stress of debris flows, Appl. Rheol. 26 (2016) 42997.

The measurement and the investigation of the errors in a Couette rheometer have been a topic of considerable interest in many rheometric studies. In the present study, a more accurate predictor-corrector method based on CFD and the analytical solution of the problem is described. Comparing to the previous CFD-based method, in addition to considering the effect of the end parts, the presented correction factors also take into account the effect of the wide gap into a single coefficient. The correction factors are computed for both Newtonian and non-Newtonian fluids in wide and narrow gap rheometry. Results showed that the shear rate distribution across the gap is highly non-linear in non-Newtonian wide gap rheometry. Moreover, for very shear thinning fluid i.e. n < 0.4 in narrow gap rheometry, there is a need to apply correction factor to the calculated fluid properties. Comparing the presented CFD approach and the current approach, the correction factor can be enhanced up to 16% depending on the fluid behavior and the gap distance.

Cite this publication as follows:
Hamedi N, Revstedt J, Tornberg E, Innings F: Application of CFD–based Correction Factors to Increase the Accuracy of Flow Curve Determination in a Couette Rheometer, Appl. Rheol. 26 (2016) 35341.

This paper represents the rheology of screen printing pastes based on BaTiO3 nanopowder. It is found that the pastes are shear thickened fluids with subsequent shear thinning under high shear rates. Different concentrations of plasticizer in organic binder lead to various conformations of ethyl cellulose molecules that influence the type of adsorption between polymer molecules and nanoparticles. The flow loop shows intervals of shear rate corresponding to rheopexy, pseudoplasticity and thixo - tropy. The appearance of rheopexy indicates that the added amount of plasticizer may be insufficient to bind the maJority of free functional groups of the polymer and the remaining groups are bound with BaTiO3 nanoparticles forming a strong structural network. But in the case of pseudoplastic structures, the polymer molecule exists in the conformation where almost all free functional groups are bound with the nanoparticle surfaces. The pseudoplastic properties of the system are caused by the structural polymer-polymer links. SEM and optical profilometry of the obtained films shows that plasticization lead to the formation of thin (less than 1 μm) smooth (Ra is equal to the size of individual BaTiO3 nanoparticle) prints.

Cite this publication as follows:
Umerova SO, Dulina IO, Ragulya AV, Konstantinova TE, Glazunova VA: Rheology of plasticized screen printing pastes based on BaTiO3 nanopowder, Appl. Rheol. 26 (2016) 33274.

The rheological behavior of thermoplastic elastomers (TPE) based on 50/50 recycled ethylenepropylene-diene monomer (r-EPDM)/polypropylene (PP) was studied to determine the effect of feeding strategy when preparing these blends using twin-screw extrusion. In particular, small and large deformation characterizations have been performed to better understand the relationships between sample preparation and final properties of the blends. It was found that small changes in blend morphology (particle size and interfacial adhesion) are better distinguished in rheological properties (melt state) under large deformation (LAOS and step shear) compared to small deformation (SAOS).

Cite this publication as follows:
Mahallati P, MahiHassanabadi H, Wilhelm M, Rodrigue D: Rheological characterization of thermoplastic elastomers (TPE) based on PP and recycled EPDM, Appl. Rheol. 26 (2016) 33503.

Rheological characterization of high-solid sludge is a fundamental requirement for optimizing the mixing and transport of high-solid sludge during anaerobic digestion in waste water treatment systems. We investigate the time evolution of physicochemical properties and rheological characteristics of high-solid digested sludge with total solids (TS) 15−20 wt.% during anaerobic digestion. A series of experiments are carried out over a period of 26 days during the operation of an anaerobic sequencing batch reactor. In equilibrium flow curves, high-solid digested sludge exhibits shear thinning behavior with a yield stress. Strong viscoelastic behavior is exhibited in the linear and non-linear regimes in dynamic and creep tests. A critical shear stress is found in the equilibrium flow curve, which accounts for the viscoelastic property. To accurately model the flow curves, a piecewise Herschel-Bulkley function separated by the corresponding critical shear rate is proposed. The digestion time plays an important role in determining the rheological behavior. Longer digestion times lead to a decreased yield stress in creep tests, and a decreased viscosity and a reduced critical shear stress in the steady flow curve. In addition, the storage modulus G' and the loss modulus G'' are reduced as digestion proceeds, leading to a shorter linear viscoelastic regime. Moreover, we find that the storage modulus G' varies linearly with the concentration of total organic matter in the sludge, suggesting that G' could be used as a new control parameter for monitoring of the anaerobic digestion process.

Cite this publication as follows:
Zhang J, Haward SJ, Wu Z, Dai X, Tao W, Li Z: Evolution of Rheological Characteristics of High-solid Municipal Sludge during Anaerobic Digestion, Appl. Rheol. 26 (2016) 32973.

Particle motion in fluid is discussed for one-particle systems as well as for dense suspensions, such as cementitious materials. The difference in large particle motion between larger particles and behaviour of fines (< 125 mm) is explained, motion of one particle is shown by numerical simulation. It is concluded and highlighted that it is the particular motion of the fines that to a large extent contribute to the rheological properties of a suspension. It is also shown why larger ellipsoidal particles do not necessarily contribute to the increase of viscosity.

Cite this publication as follows:
Gram A, Silfwerbrand J, Lagerblad B: Particle Motion in Fluid - Analytical and Numerical Study, Appl. Rheol. 26 (2016) 23326.

Cite this publication as follows:
Jarnstrom L: Highlights from the 24th Nordic Rheology Conference (NRC 2015), Appl. Rheol. 26 (2016) 53.

DLS Microrheology involves tracking the time dependent motion or mean square displacement of dispersed tracer particles of known size using Dynamic Light Scattering (DLS) in order to determine viscoelastic properties of the dispersion medium. The viscoelastic moduli are calculated using a generalised form of the Stokes-Einstein equation which requires Fourier Transformation of the MSD. An alternative approach for estimating the viscoelastic moduli uses a modified algebraic form of the generalized Stokes-Einstein equation, which employs a power law expression to describe the local change in MSD with time. Since the mean square displacement is linearly related to the creep compliance, it can be shown that the same algebraic approach can also be applied to creep measurements made on a rotational rheometer, giving access to the low frequency moduli in a fraction of the time required for oscillatory testing. Furthermore, the quality of the conversion process can be improved by fitting a Burgers model to the time domain data prior to conversion thus minimising errors associated with local differentiation, which is fundamental to the conversion approach.

Cite this publication as follows:
Duffy JJ, Rega C, Jack R, Amin S: An algebraic approach for determining viscoelastic moduli from creep compliance through application of the Generalised Stokes-Einstein relation and Burgers model, Appl. Rheol. 26 (2016) 15130.

Measurements and modeling of the nonlinear viscoelastic properties of a high viscosity silicone oil (polydimethylsiloxane, PDMS) are reported. LAOS test were performed with a high precision rotational rheometer to probe the nonlinear response. The measurements show that the material can be safely considered linear below strain amplitude 1. The viscous LissaJous-Bodwitch curves indicate intracycle shear thinning, whereas the elastic LissaJous-Bodwitch curves indicate intracycle strain stiffening in the nonlinear regime. Secondary loops in some of the measured viscous stress curves are attributed to a non-sinusoidal shear rate signal. A multi-element White-Metzner model is used as a constitutive equation, which accurately describes the LAOS data in all measured cases. Based on the extension of the measured data by simulations, nonlinear properties are analyzed both for the elastic and for the viscous part. It is observed that the nonlinearity considerably increases the weight of the higher harmonics in the shear stress signal. It is predicted that the viscous nonlinearity has a maximum around 50 rad/s angular frequency, and that the elastic nonlinearity becomes nearly independent of the angular frequency above 30 rad/s.

Cite this publication as follows:
Kokuti Z, Volker-Pop L, Brandstatter M, Kokavecz J, Ailer P, Palkovics L, Szabo G, Czirjak A: Exploring the nonlinear viscoelasticity of a high viscosity silicone oil with LAOS, Appl. Rheol. 26 (2016) 14289.

Alexei Likhtman, a leading scientist in Theoretical Soft Matter Physics, has died aged 44

Born in 1971 into a family with strong scientific tradition, Alexei was educated in Moscow. He was awarded a Diploma in Physics with honours from the Physics Department of Moscow State University (MGU) in 1994. He remained at MGU for his PhD research, supervised by Professor Alexander Semenov. The topic, his first foray into polymer physics, was the calculation of the extraordinary ordered nanoscale patterns of chemical separation that are spontaneously generated within polymer melts whose molecules contain extended regions of different chemistry but Joined together. These systems maintained a lifelong fascination for Alexei, as did the collaboration with the experimental group in Crete that the Russians worked with closely. The relationship with Crete remained strong and close until the end of Alexei's life. A more important lifelong partnership also began in Moscow - it was as students there that Alexei and Katrina met and married in December 1990. The family grew after their daughters Sonya and Asya were born while Alexei was working on his PhD thesis. Helping to look after two little girls however did not stop him from producing a high quality piece of work. Till the end of his days Alexei remained a loving, committed, hands on dad, always reliable and extremely loyal to his family. The family stayed in Moscow for two more years, with Alexei as a Scientific Fellow at Moscow State University, before moving to the U.K, in 1998, where he took up a position as a Research Assistant in the Department of Applied Mathematics at Leeds University, where Semenov, now his colleague, had also moved. That initial one year position marked the beginning of family's long life in the UK

Alexei stayed at Leeds from 1998 until 2007: in 1999 he moved to the Department of Physics and Astronomy, where he worked on theories of fast flow of entangled polymer melts, including theory and simulations of the convective constraint release model, supervised by Professor Tom McLeish, and working collaboratively with Prof. Scott Milner at an ex tended international workshop at the Kavli Institute of Theoretical Physics in Santa Barbara. In 2002, Alexei’s research had developed to the point where he was awarded an Advanced EPSRC Fellowship, which he held from 2002-2005 in the School of Physics and Astronomy. In this period, Alexei worked on developing new models of polymer dynamics, simultaneous description of rheology, neutron spin-echo, neutron scattering, diffusion, dielectric spectroscopy and NMR experiments, the theory of chemical reactions in polymers and computer simulations. This work has been recognized in many ways, including the best paper award of the Journal of Rheology (2006). From 2005-2007 Alexei held his Fellowship in the Department of Applied Mathematics, also as University Fellow, supervising a team of three postdoctoral researchers working on molecular simulations of polymer melts, slip-links model of entanglements and experimental rheology. Although a theoretician, he worked with experimental colleagues in different laboratories and performed experiments himself, learning and questioning every single detail. As a result, he personally developed the most reliable experimental protocol for measuring the flow properties of polymer melts yet found by the Leeds lab. For an experimentalist, it was a treat to interact with Alexei in this context, a unique experience that led to improved experiments. Co-supervising a PhD student, Richard Graham, the two formulated a now-celebrated non-linear but easily-computable mathematical model for the flow of linear polymers of well-defined length (the ROLiE-Poly model).

He worked hard not only on brilliant new theoretical science, but on making this accessible to others. For example, his foresight and energy led to the creation, with long-time colleague Jorge Ramirez, of a free software tool (called REPTATE) that enabled experimental scientists in universities and industry to sort their polymer flow data and compare it quickly and efficiently to theoretical models, greatly accelerating fundamental research and its application.

In May 2007, Alexei moved to the Department of Mathematics and Statistics at the University of Reading, as Professor of Mathematical Physics. There, together with Prof. Mark Matsen, he created a new group of theoretical polymer physics and within a few years had put Reading ‘on the map’. The group focused on the microscopic foundations of the tube theory and using a blend of theory and multi-scale simulation to dig deeper, and with more care, into the underlying physics than any other group in the world. A testimony of Alexei’s brilliance is his unique ability to bridge concepts and methodologies from different fields. He did so in his recent simulation work by using concatenated ring polymers to study polymer entanglements.

Alexei achieved enormous academic distinction, and his achievements came remarkably quickly – testament to his brilliance as a scientist. Several theoretical works on the linear and non-linear viscoelasticity of entangled polymers carry his name, including the famous Likhtman-McLeish model (2002) for slow flows (which was 90% Likhtman) and the GLaMM model (2003) for fast flows (with Graham and Milner). His Advanced EPSRC Fellowship came at the age of 31, and he was appointed Professor of Mathematical Physics in Reading at the age of Just 35. Yet while undoubtedly successful himself, Alexei was equally proud of the many achievements of the group he developed. For example, in September this year he spoke glowingly of how two poster prizes out of three available at the Institute of Physics Polymer Physics Biennial Conference were won by post-doctoral researchers from his team. In the same month, he was appointed as the first Mercator Fellow of the Freiburg-Strasbourg-Basel-Mulhouse International Research Training Group on 'Soft Matter Science'. He enJoyed a productive visit to Strasbourg, during which he described himself as "feeling like a PhD student again" (possibly partly due to the position that his former PhD supervisor, Semenov, now holds there!). This is typical of his modesty and enthusiasm.

Alexei was one of those wonderful scientists who remind us that Just because something is obvious, doesn't make it true. Alexei would challenge every idea that we had at Leeds – including the ones that we thought were obviously true. But the way in which he demolished your ideas was so kind and so surgically precise that it always felt good somehow. He was a particularly vociferous critic of the bad habit that much of the polymer rheology community had got into, of presenting theory together with data from Just one technique, then subtly altering the parameters when data from a different technique was brought into comparison. A wonderful paper from 2005 compared his remarkable ‘slip-link model’ to data on rheology, NMR and diffusion measurements simultaneously. He leaves us a permanent reminder that you learn more from theory when it disagrees with experiment and that an experimentalist should have a good grasp of theory and vice versa.

Alexei was a wonderful colleague, and all those who were lucky enough to work with him benefitted immensely from his enthusiasm, support and wisdom. Alexei was an intellectual powerhouse, a truly curious mind, a wonderfully creative thinker, a brilliant teacher at undergraduate and graduate levels, with academic gravitas way beyond his years, yet completely ap proachable, modest and always friendly in a natural way that charmed anybody who met him. The superb group he built in Reading and the quality of people he brought in reflect his vision and sense of commitment.

He was hugely supportive of those for whom he felt he had a responsibility. His dedication to his PhD students and his research team went well beyond professional duty. He sought to provide a family-like environment for the group, especially supportive for those who were far from home. He presented himself as an exemplary reference figure for all the young people in his group, full of energy and full of life. In this continuous work of hospitality and welcome he was supported by his family, to whom he was utterly devoted as husband and father.

Alexei was so much more than an academic and an intellectual. He truly enJoyed life and always managed to combine professional activities with hobbies and family activities. He did so last summer when he visited friends with his family following a workshop and seminar. He had a passion for so many things ranging from sports (especially swimming and hiking) to photography. A truly happy, free spirited man, full of energy and passion for things he did, he had as infectious a love of life as a tireless desire to find scientific truth. He was a great admirer of nature and outdoors with real care about the world and people around him. He was a great friend, a funny, spirited, yet always serious person, and his daily passionate presence, his enthusiasm for science, his warm friendship, will be sorely missed.

Alexei died on 11 October 2015 following a fall while hiking in Maryland, USA. He is survived by his wife Katrina, and their two daughters, Sonya and Asya.

Cite this publication as follows:
McLeish TCB: Obituary Alexei Likhtman (1971-2015), Appl. Rheol. 25 (2015) 53.

Traditional Maxwell-type models have limitations when applied to the flows of real polymers containing macromolecules and complex microstructures. The main weakness of Maxwell models is the use of relaxation-time spectra that conducts to ill-posed problems in integral functions, and shear-induced relaxation spectrum transformations may lead to non-linearity. In contrast, control theory, which has apparently not been applied in rheology so far, enables modelling without knowledge of relaxation times. This study used viscoelastic constitutive equations derived from control theory and a new polymer fingerprint, which we call the rheologically effective distribution (RED). The study shows that a relaxation-time scheme is not essential to describe viscoelasticity, and applying the RED to computational modelling provides many theoretical and practical benefits, including giving higher accuracy. The proposed model is versatile and presents viscoelastic formulas for shear viscosity and other types of flow. Furthermore, the new model provides explanations for the empirical Cox-Merz rule and a power law behavior, the origin of which is frequently disputed in rheology.

Cite this publication as follows:
Borg T, Paakkonen EJ: Linear viscoelastic model for different flows based on control theory, Appl. Rheol. 25 (2015) 64304.

Despite the economic and ecologic importance of pine oleoresins, their rheology remains little explored. In this report we describe rheological properties of oleoresins produced by mature trees of four southern pines native to North America (loblolly, slash, longleaf, shortleaf). Results indicate that these oleoresins are structured fluids that exhibit viscoelastic behavior, but differ in flow behavior. Slash pine oleoresin exhibited Newtonian flow behavior while the oleoresin from the longleaf and shortleaf pines showed pseudoplastic behavior and the loblolly pine oleoresin showed Bingham fluid behavior with a yield stress of about 1.980 Pa. Temperature-dependent viscosities for the oleoresin samples studied were well described by the Arrhenius model, yielding flow activation energies ranging from 153.5 to 219.7 kJ/mol. The viscosity of the slash pine oleoresin sample was found to be less sensitive to temperature than that of the shortleaf or longleaf pine samples. The time-temperature superposition principle was successfully applied to pine oleoresins to show behavior over the temperature range of 25 - 65°C typical for a thermorheologically simple system. Such behavior is consistent with the temperature dependent viscoelastic properties found for these complex fluids, and supports the effective use of rheological evaluations for describing physical properties of pine oleoresins.

Cite this publication as follows:
Belyamani I, Otaigbe JU, Nelson D, Strom B, Roberds J: Rheological properties of southern pine oleoresins, Appl. Rheol. 25 (2015) 53708.

Magnetic nanoparticles suspended in suitable carrier liquids can be adopted for use in biomedicine. For this to be achieved, the biocompatibility of these ferrofluids needs to be ascertained. In cancer treatment, potential applications currently under investigation include, e.g. drug targeting by using magnetic fields and the destruction of diseased cells by applying alternating magnetic fields, which cause heating of magnetic nanoparticles. To enable the use of ferrofluids in the actual biomedical context, detailed knowledge of the flow characteristics is essential to ensure safe treatment. From ferrofluids used in the engineering context, a rise of viscosity when a magnetic field is applied - the magnetoviscous effect - is well known. This effect, which leads to an increased viscosity and profound alteration of a fluid's rheological behaviour, has also been demonstrated for biocompatible ferrofluids used in the aforementioned applications. In biomedical applications, ferrofluids will be diluted in the blood stream. Therefore, the interaction between whole blood and the ferrofluid has to be investigated. This is the focus of the current experimental study, which makes use of two different ferrofluids diluted in sheep blood to gain a deeper understanding of the fluid mixtures primarily regarding the relative change in viscosity if an external magnetic field is applied. The results demonstrate a strong interaction between blood cells and structures formed by the magnetic nanoparticles and show a high deviation of results compared to ferrofluids diluted in water. These findings have to be taken into account for future research and applications of similar biocompatible fluids to guarantee safe and effective use in living organisms.

Cite this publication as follows:
Nowak J, Nowak C, Odenbach S: Consequences of sheep blood used as diluting agent for the magnetoviscous effect in biocompatible ferrofluids, Appl. Rheol. 25 (2015) 53250.

We provide methodologies to characterise the rheology of ultra-low volumes of polymer solutions and biological fluids (10 - 100 μL) on a rotational rheometer. The technique utilises a parallel plate geometry with narrow gaps of 20 - 100 micrometers, which is an order of magnitude less than conventional methods. Despite the complications these gaps present, the use of appropriate protocols ensures reliable and accurate rheological characterisation of fluids, including shear-dependent viscosity, normal stresses and linear viscoelasticity. This rheological technique.s usefulness is further demonstrated by showing how the rheology of hyaluronan solutions evolve during fermentation. The intrinsic viscosity of the hyaluronan macromolecule is determined using less than 100 μL of solution extracted directly from the bioreactor, and this is used to provide a reasonable indicator of its molecular weight as it develops during the fermentation process. The ability to measure rheology of ultra-low volumes has applications in the characterisation of biological fluids and high value macromolecules, as well as generally in biotechnology and nanotechnology research fields.

Cite this publication as follows:
Boehm MW, Shewan HM, Steen JA, Stokes JR: Illustrating ultra-low-volume rheology on a conventional rheometer: Charting the development of hyaluronan during fermentation, Appl. Rheol. 25 (2015) 55609.

Cite this publication as follows:
Handge UA: Flow-Induced Structures in Complex Fluids (Joint DRG & DPG symposium 2015), Appl. Rheol. 25 (2015) 45.

There is often a necessity to measure, or at least estimate, true viscosity values using non-standard measuring systems on a rotational rheometer. This may be to replicate a mixing or manufacturing process on a lab scale, to keep a sample dispersed and uniform during a measurement or to measure some rheological property that would be difficult or impossible with a standard configuration. Such measurements can be made easily enough, but without a process for converting torque to shear stress and angular velocity to shear rate only these raw data variables can be reported. In this paper a simple and novel empirical method for determining strain/strain rate C1 and stress C2 constants for non-standard measuring systems on a rotational rheometer is presented. This method uses relative torque measurements made with a Newtonian and non-Newtonian material and their corresponding power law fitting parameters to determine C1 and C2 using a non-linear regression analysis. Equilibrium flow curves generated for two non-Newtonian fluids using two non-standard mixing geometries show very good agreement with data generated using a standard cone and plate configuration, therefore, validating the approach.

Cite this publication as follows:
Duffy JJ, Hill AJ, Murphy SH: Simple method for determining stress and strain constants for non-standard measuring systems on a rotational rheometer , Appl. Rheol. 25 (2015) 42670.

Cite this publication as follows:
Leal C, Patricio P, Tavares J, Teixeira P: 9th Liquid Matter Conference (Liquids 2014), Appl. Rheol. 25 (2015) 62.

The creep and recovery of asphalt modified with Elvaloy 4170 and polyphosphoric acid were studied at low temperatures, by inductive phenomenological methods. Two models of the tensile compliance function were investigated. Both models were derived from the linear viscoelastic retardation spectra and successfully used for the description of the creep and recovery tests in the studied asphalt binders. Large effects due to oxidative aging in a rolling thin film oven were found from the recovered compliance function recorded in a bending beam rheometer at a temperature of - 20 C. The studied compliance function models worked well at higher and lower temperatures in creep and recovery experiments on conventional and modified asphalt binders for both shear and tensile creep.

Cite this publication as follows:
Hampl R, Vacin O, Jasso M, Stastna J, Zanzotto L: Modeling of tensile creep and recovery of polymer modified asphalt binders at low temperatures, Appl. Rheol. 25 (2015) 34675.

As a fundamental rheological property, shear yield stress is used to assess the flowability of suspensions. Slump test is a cheap and quick experiment which is commonly used to estimate shear yield stress on-site. It has been generally believed that, cylinder height to diameter ratio and lifting velocity has no effect on the slump test results. In this work, the sensitivity of the slump test to the height to diameter ratio and lifting velocity of cylinder was investigated. ProJections on the top surface of suspension column after the slump test were also analyzed. Results indicated that, the effect of cylinder height to diameter ratio is negligible in the low range of shear yield stress, while it is remarkable in the high range. It was deduced that, using a cylinder with dimension ratio in the range of 0.83 to 1.15 is more reliable. Furthermore, it is shown that the lifting velocity of cylinder has a significant effect on the results. A high lifting velocity could introduce a great error in estimation particularly in a large height to diameter ratio.

Cite this publication as follows:
Garmsiri M, HajiAminShirazi H, Yarahmadi M: An analysis of the influence of cylinder dimension ratio and lifting velocity on the slump test results, Appl. Rheol. 25 (2015) 23416.

Maximizing oil recovery from current reserves is becoming more important as global usage continues to rise. In this paper, we present the development of two microfluidic sandstone devices of high complexity and differing permeability capable of quickly and inexpensively testing the oil recovery performance of fluids with different rheological properties. Our initial baseline experiments were performed by displacing oil with water over a wide range of flow rates. Next, a commercially available fluid thickener, Flopaam 3630, was tested. Flopaam is both shear thinning and viscoelastic and was found, due primarily to its large viscosity, to recover more oil than the water and increase the oil recovery substantially in both the larger and smaller permeability microfluidic sandstone devices. Finally, a shear-thickening nanoparticle solution was studied. The shear-thickening solution was designed to thicken at a shear rate of about 10 s-1, a typical shear rate in the oil reservoirs. These shearthickening fluids were found to be an excellent enhanced oil recovery fluid, especially when the shear rates within the microfluidic sandstone devices closely matched the shear rates associated with the shear-thickening regime. For the high permeability sandstone devices tested, when the appropriate choice of shear-rate-dependent viscosity was used to define a capillary number, the oil recovery obtained from both the Newtonian and non-Newtonian fluids were found to collapse quite well onto a single master curve. This, however, was not the case for the lowest permeability sandstone devices where the increased complexity was found to negatively affect the performance of the viscoelastic fluid when compared to either the Newtonian or the shear-thickening fluid. Finally, it was shown that these oil recovery results are insensitive to whether a single-stage recovery process or a more complex two-stage recovery process that starts with an initial water flood followed by a flood with a secondary fluid were used.

Cite this publication as follows:
Nilsson MA, Rothstein JP: Effect of fluid rheology and sandstone permeability on enhanced oil recovery in a microfluidic sandstone device, Appl. Rheol. 25 (2015) 25189.

Viscosity reduction of aqueous kaolin suspensions by conventional additives (deflocculation) is studied, using standard viscosity measurements. Apparent viscosity at 100 s-1, and flow behavior index n give complex information about changes of viscosity and flow character of deflocculated suspensions. Several widely used deflocculants - electrolytes and polyelectrolytes - are tested in a wide range of concentrations. The optimum concentrations of these deflocculants, which result in minimum apparent viscosity of suspension, are found. Sedimentation stability of deflocculated suspensions is monitored. Inorganic electrolytes are found to be more effective in viscosity reduction. On the other hand, low-molecular-weight polyelectrolytes produce more stable final suspensions.

Cite this publication as follows:
Penkavova V, Guerreiro M, Tihon J, Teixeira JAC: Deflocculation of kaolin suspensions - The effect of various electrolytes, Appl. Rheol. 25 (2015) 24151.

For developing a new composite material owning shear-thickening characteristic, the rheological behaviors of nano-sized precipitated calcium carbonate (PCC) particles with irregular sharp in glycerine were investigated systematically by means of steady and dynamic rheometry. The results showed that the concentrated PCC suspensions exhibit a strong shear-thickening behavior under both steady and dynamic oscillatory shear when the volume fraction of PCC above the threshold (about 41 %). In steady shear tests, the critical shear rate decreases and the maximum viscosity in shear thickening region increases dynamically with the increase of volume fraction. While, for suspensions with different volume fractions, the similar critical stress for the onset of shear thickening is found. In dynamic strain sweep at different fixed frequencies, with the increase of fixed frequency, the complex viscosity of suspensions decreases slightly, while the critical strain for shear-thickening shifts to lower value. The dynamic oscillatory rheological behavior of suspensions at low frequency (w < 100 rad/s) could be reasonably interpreted in terms of the steady shear behavior. For the suspensions with same volume fraction, it was interestingly found that the critical dynamic shear rate equaled to the product of critical strain and frequency could agree well with the critical shear rate in steady shear. Moreover, the rheological behavior of PCC suspensions shows excellent reversibility and reproducibility.

Cite this publication as follows:
Chen Y, Xu W, Xiong Y, Peng Y, Peng C, Ou Z: Shear-Thickening Behavior of Precipitated Calcium Carbonate Particles Suspensions in Glycerine, Appl. Rheol. 25 (2015) 12466.

An elasto-visco-plastic model of the Cauchy stress is proposed for gluing solution of railway ballast, with an asymptotic timedependent viscosity accounting for the anti-thixotropic and shear-thickening features. Flow characteristics and time-dependent solidification of the gluing solution in the multiconnected conducts spanned by the gravels, accomplished by the algorithm in generating a ballast consisting of convex octahedral grains, are simulated by using the ANSYS™ package. While different vertical penetrations of the gluing solution can be achieved by using different characteristic times scales of the asymptotic time-dependent viscosity, the lateral extension is rather limited and local. Pouring gluing solution into ballast tends to create more concrete adhesion between the gravels vertically, while concrete lateral adhesion can be obtained by spreading gluing solution onto ballast. The present study provides an integrated method for the estimation of the gluing solution distribution in a ballast, and for optimal layout of the gluing solution arrangement a priori gluing practice.

Cite this publication as follows:
Fang C, Lee Y, Kuo C, Lin Y, Kuo C: Anti-thixotropic non-Newtonian fluid in complex conduct: gluing process simulation of railway ballast, Appl. Rheol. 25 (2015) 14381.

A Sentmanat Extension Rheometer represents one out of a few experimental devices for the measurement of elongational viscosity of polymer melts. However, the appropriateness of this technique for individual polymer materials is not sufficiently apparent and in some case is disregarded or ignored. The proposed visualization technique is based on imprinting painted pattern from the inner surface of the studied polymer samples onto the counter-rotating drums. Digitization of the imprinted pattern gives a possibility to evaluate a degree of sagging, incorrect fixing of rectangular polymer samples to the drums, possible appearance of sample inhomogeneity (variance in thickness, bubbles, etc.). The presented visualization technique is demonstrated using branched LDPE Escorene. Two various imprinted patterns are applied. First, the upper and lower contours are charted on a prepared sample with the aim to determine the sample shapes during stretching and to compare them with the theoretical ones. Second, the inclined rectangular grid pattern is charted for evaluating possible inhomogeneity of the sample.

Cite this publication as follows:
Pivokonsky R, Filip P, Zelenkova J: Visualization of elongation measurements using an SER universal testing platform, Appl. Rheol. 25 (2015) 13636.

Cite this publication as follows:
Dhir V: International Conference on Heat Transfer and Fluid Flow (HTTF 2014), Appl. Rheol. 24 (2014) 48.

Measurements and modeling of rheological properties of a high viscosity silicone oil (polydimethylsiloxane, PDMS) at high frequency are reported. The linear viscoelastic properties are measured by small amplitude oscillation shear (SAOS) tests with a rotational rheometer. Furthermore, Diffusing Wave Spectroscopy (DWS) is used, which expands the angular frequency range of the measured loss and storage moduli up to 105 rad/s, in a temperature range of 20 - 70 C. Good agreement between both methods is found in the overlapping frequency region, especially at higher temperatures. The DWS data show that the elastic modulus stays dominant and increases with frequency, without a second cross-over point up till 108 rad/s. Flow curves, measured with rotational and with capillary rheometry up to a shear rate of 7.6 × 104 s-1, show shear thinning behavior, which implies nonlinear viscoelasticity. Comparison of the dynamic and complex viscosity shows that the Cox-Merz rule is valid in a frequency range spanning six orders of magnitude. A multi-element White-Metzner model is proposed as a constitutive equation, which accurately describes the nonlinear viscoelastic properties, including the decrease of the loss and storage moduli during amplitude sweeps in oscillatory shear measurements.

Cite this publication as follows:
Kokuti Z, vanGruijthuijsen K, Jenei M, Toth-Molnar G, Czirjak A, Kokavecz J, Ailer P, Palkovics L, Volker AC, Szabo G: High-frequency rheology of a high viscosity silicone oil using diffusing wave spectroscopy, Appl. Rheol. 24 (2014) 63984.

The knowledge of enzymatic activity is necessary in many industrial processes. The common measurement techniques are time-consuming and therefore cost-intensive. Measurements of viscosities are a promising approach as a fast and cheap testing method. The maJor challenges are to find a suitable substrate with Newtonian flow behavior throughout the whole testing range as well as a correlation between viscosity of the solution and the decomposed mass. Water based gelatinebuffer- system as substrate is tested extensively regarding the dependence on different solvents, pH-values and gelatine batches. All viscosity measurements are performed with a rotational viscometer. It is shown that the gelatine-buffer-system is independent of the given parameters and found to fulfill the said requirements. A correlation model based on the Martin equation and necessary assumptions are presented. The required parameters intrinsic viscosity and Martin parameter can be derived by few measurements with little effort. The digesting enzyme Trypsin is used as model enzyme in the degradation experiments. The enzyme concentration is varied and the decrease of the viscosity is measured. A dependency between the enzyme concentration and the enzymatic activity or respectively the viscosity decrease is observed.

Cite this publication as follows:
Sellerberg M, DiBartolo D, Oberrecht J, Tiller J, Walzel P: Viscometric measurement of protease activities on gelatine substrate, Appl. Rheol. 24 (2014) 62660.

Fruit Juices concentrated by osmotic distillation are characterized by higher organoleptic and sensorial properties than those of Juices concentrated by thermal evaporation as confirmed by several research studies. On the other hand, no literature is readily available about the rheological characterization of Juices concentrated by osmotic distillation. This work aimed at investigate the rheological behavior of the concentrated blood orange Juice prepared from the clarified Juice by using thermal evaporation and osmotic distillation processes as a function of solids concentration in the range 115 - 614 g/kg of total soluble solids (TSS) within a range of 20 - 70 C. The effect of the temperature and concentration on the Juice viscosity was studied. Arrhenius-type correlation equations for viscosity were used to represent the temperature dependence of viscosity. Values of the Arrhenius equation parameters (flow activation energy) were calculated for the measured viscosities of Juices as a function of concentration. Results indicated no significant differences in the rheological behavior for orange Juices concentrated with both methods. The Juices exhibited a Newtonian behavior regardless of the concentration method.

Cite this publication as follows:
OlivieroRossi C, Destani F, Cassano A: Rheological behavior of blood orange juice concentrated by osmotic distillation and thermal evaporation, Appl. Rheol. 24 (2014) 63776.

Cite this publication as follows:
Lopez-Lopez MT, Rodriguez-Arco L, Duran JD, Gonzalez-Caballero F: 14th International Conference on Electrorheological Fluids and Magnetorheological Suspensions (ERMR2014), Appl. Rheol. 24 (2014) 55.

This work presents a technique based on optical tracking of the free fall in a Newtonian fluid used in falling ball viscometers. Classical techniques have shown, on one hand a limit in the ball falling height measurement, on the other hand a limit in the accuracy estimation of velocity and therefore a weak precision on the viscosity calculation of the fluids. Our method consist to measure the fall height by taking video scenes of the ball during its fall and thus to estimate its terminal velocity which is a preponderant parameter in the kinematic velocity computing, using both the Stokes or Hoppler formalisms. The precision reached in this approach adJoins encouraging values for future works in the purpose to improve this method further.

Cite this publication as follows:
Kheloufi N, Lounis M: An optical technique for Newtonian fluid viscosity measurement using multiparameters analysis, Appl. Rheol. 24 (2014) 44134.

In this work, the viscosity of soybean oil subJected to thermal degradation has been determined and related to the chemical composition of the oil. In particular, it is found a linear relationship between the viscosity value and the triglycerides content during the degradation process (an increase of the former is associated to a decrease of the latter). Thus, it is shown that viscosity provides us a reliable way of measuring oil degradation and, insofar as proportional to flow time, it allows for the design of simple devices to control the oil quality. Besides, the study of the viscosity behavior along with the changes in composition during the cooking time, i.e. the period of time that the oil is being heated, give us valuable information about the type of chemical reactions occurring within the oil.

Cite this publication as follows:
Olivares-Carrillo P, PerezdelosRios A, Quesada-Medina J, HernandezCifre JG, DiazBanos FG: Viscosity as a measure of oil composition changes due to thermal degradation, Appl. Rheol. 24 (2014) 53667.

This historical study deepens the rheologist.s understanding of the motto of The Society of Rheology, of its history, and of its many typographies. The motto "παντα ῥει" is not verbatim something written or said by the ancient Greek Ionian philosopher Heraclitus, ca. 540 - 480 BCE. Rather it is first encountered much later, in the writings of the Roman Simplicius ca. 490 - 560 CE. Thus, although it is uniformly agreed by Greek scholars that it correctly and concisely distills Heraclitian philosophy, that of constant change, and although this is appropriately used as the motto of The Society of Rheology, there is little point in trying to rewrite it into another form (for example to capitalize it) in an effort to be more faithful to an ancient prototype. Rather, we suggest simply reinstating the two missing diacritical marks, and thus, to express it as "πάντα ῥεῖ" which is the form in which the motto was introduced in 1929. This is also consistent with current typography of ancient Greek writings, in use since the ninth century CE, following the byzantine scholars. We provide Table 1 to facilitate accurate typesetting of the motto.

Cite this publication as follows:
Beris A, Giacomin AJ: πάντα ῥεῖ: Everything flows, Appl. Rheol. 24 (2014) 52918.

Cite this publication as follows:
Plog JP: Spreadability of cream cheese - Influence of temperature and fat content, Appl. Rheol. 24 (2014) 10.

Large amplitude oscillatory shear (LAOS) rheology is often performed in order to complement steady simple shear (SSS) rheology, i.e., probe rheological properties of materials that cannot be not observed with SSS alone. However, it is difficult to measure the SSS rheology of some problematic materials due to fracture and eJection, and LAOS may alleviate these issues, at least partially. Therefore, it is of interest to obtain SSS rheology information from LAOS measurements. We show that a constitutive modeling approach may be used to unify the analysis of LAOS data obtained from different viscometric geometries and modes of control and that the LAOS data may be used to predict SSS profiles. A model elastoviscoplastic material, a Carbopol solution, was used to validate the approach experimentally. LAOS rheometry of problematic biomass slurries was also performed, and the SSS profiles for the slurries were predicted with more confidence than could be obtained from SSS measurements directly.

Cite this publication as follows:
Stickel JJ, Knutsen JS, Liberatore MW: Connecting large amplitude oscillatory shear rheology to unidirectional shear rheology and application to biomass slurries, Appl. Rheol. 24 (2014) 53075.

A novel shear thickening suspoemulsion is formulated and studied with a new rheo-microscope instrument. The experimental fluid system is comprised of a immiscible blend of Newtonian, low molecular weight poly(dimethylsiloxane) and a shear thickening suspension of colloidal silica in poly(ethylene glycol). The blend is studied as a function of composition where phase inversion is evident at low shear rates and is found to be shear rate dependent. A shear thickening viscosity curve is observed when blends comprised of shear thickening fluid dispersed as droplets are subJected to high shear rates. Dispersing a continuously shear thickening fluid, φsilica = 0.42, results in continuously shear thickening response from the blend. Dispersing a discontinuously shear thickening fluid, φsilica = 0.51, results in bulk shear thickening that can also be discontinuous. Shear thickening in the final suspoemulsion is consistently first detected at φSTF = 0.2, with the magnitude of shear thickening being dependent on the particle concentration in the STF phase. The onset of shear thickening also corresponds with the formation of extended droplet structures in the fluid. The complex properties of these suspoemulsions and the ability to formulate dispersed droplet morphologies in this mixture are shown to result from the underlying shear thickening rheology of the dispersed phase.

Cite this publication as follows:
Fowler JN, Kirkwood J, Wagner NJ: Rheology and microstructure of shear thickening fluid suspoemulsions, Appl. Rheol. 24 (2014) 43049.

This paper is concerned with the numerical solution of polymer melt flows of both extrudate-swell and tube-tooling dieextrusion coatings, using a hybrid finite element/finite volume discretisation fe/fv. Extrudate-swell presents a single dynamic free-surface, whilst the complex polymer melt coating flow exhibit two separate free-surface draw-down sections to model, an inner and outer conduit surface of the melt. The interest lies in determining efficient windows for process control over variation in material properties, stressing levels generated and pressure drop. In this respect, maJor rheological influences are evaluated on the numerical predictions generated of the extensional viscosity and Trouton ratio, when comparing solution response for an exponential Phan-Thien Tanner (EPTT, network-based) model to that for a single extended Pom-Pom (SXPP, kinematic-based) model. The impact of shear-thinning is also considered. Attention is paid to the influence and variation in Weissenberg number We, solvent-fraction β (polymeric concentration), and second normal stress difference N2 (ξ parameter for both EPTT, and α anisotropy parameter for SXPP). The influence of model choice and parameters upon field response is described in situ through, pressure, shear and strain-rates and stress. The numerical scheme solves the momentum- continuity-surface equations by a semi-implicit time-stepping incremental Taylor-Galerkin/pressure-correction finite element method, whilst invoking a cell-vertex fluctuation distribution/median-dual-cell finite volume approximation for the first-order space-time hyperbolic-type stress evolution equation.

Cite this publication as follows:
Al-Muslimawi A, Tamaddon-Jahromi H, Webster MF: Numerical computation of extrusion and draw-extrusion cable-coating flows with polymer melts, Appl. Rheol. 24 (2014) 34188.

This work contributes to the theory of strain controlled large amplitude oscillatory shear (LAOS) as well as modelling the key properties of type III behavior of Hyun, the decreasing storage modulus and a loss modulus with considerable maximum. The latter two can be modelled with the help of the Prandtl element. Since it is a yield stress fluid, the use of LAOS is necessary to calculate the storage and loss modulus. Furthermore, a condition is presented which has to be met in order to avoid even harmonics. The storage and loss modulus as well as the higher harmonics of the Prandtl element are determined analytically in this work. They are given as mathematical functions which can be discussed conveniently. This allows the identification of characteristic points which are related to material parameters of the Prandtl element and enable a physically motivated material parameter identification. Beside this, it is observed that the yield strain do not coincide with the crossover G'(γ) = G''(γ) but with the increasing of the loss modulus and the decreasing of the storage modulus. Thanks to the analytical calculations, it is also obvious that the stress response of yield stress fluids does not necessarily include even harmonics. In this work the steady state stress response of the Prandtl element is also presented as LissaJous plots and Pipkin diagrams to visualise the rheological fingerprint.

Cite this publication as follows:
Boisly M, Kastner M, Brummund J, Ulbricht V: Large amplitude oscillatory shear of the Prandtl element analysed by Fourier Transform Rheology, Appl. Rheol. 24 (2014) 35478.

Phase-separable particulate-containing gel structures constitute complex fluids. In many cases they may incorporate component concentration inhomogeneities within the ensemble matrix. When formulated into high consistency suspensions, these can lead to unpredictable time-dependent variations in rheological response, particularly under shear in simple parallel plate and cylindrical rotational geometries. Smoothing function algorithms are primarily designed to cope with random noise. In the case studied here, namely nanocellulose-based high consistency aqueous suspensions, the system is not randomised but based on a series of parallel and serial spatial and time related mechanisms. These include: phase separation, wall slip, stress relaxation, breakdown of elastic structure and inhomogeneous time-dependent and induced structure re-build. When vacuum dewatering is applied to such a suspension while under shear, all these effects are accompanied by the development of an uneven solid content gradient within the sample, which further adds to transitional phenomena in the recorded rheological data due to spatial and temporal differences in yield stress distribution. Although these phenomena are strictly speaking not noise, it is nevertheless necessary to apply relevant data smoothing in order to extract apparent/process viscosity parameters in respect to averaging across the structural ensemble. The control parameters in the measurement of the rheological properties, to which smoothing is applied, are focused on parallel plate gap, surface geometry, shear rate, oscillation frequency and strain variation, and relaxation time between successive applications of strain. The smoothing algorithm follows the Tikhonov regularisation procedure.

Cite this publication as follows:
Dimic-Misic K, Nieminen K, Gane PA, Maloney T, Sixta H, Paltakari J: Deriving a process viscosity for complex particulate nanofibrillar cellulose gel-containing suspensions, Appl. Rheol. 24 (2014) 35616.

Rheological and electrical properties of polymeric nanoparticle solutions and their influence on the rheological and electrical properties of red blood cell (RBC) suspensions have been studied. Poly(acrylic acid) macromolecules of different architecture and molecular weight were used: (i) a new core.shell type star polymer whose interior forms hyperbranched polystyrene bearing arms of poly(acrylic acid) with molecular weight Mn = 56 920 Da and (ii) linear polyacrylic chains with average molecular weights Mn = 6000, 20000, and 225000 Da. The polymers dissolved in physiological solution with weight concentrations 1 mg/ml and 0.2 mg/ml were used for the experiments. Under physiological conditions the star-shaped macromolecules present spherical nanoparticles while the linear poly(acrylic acid)s adopt an extended chain conformation close to rod-like particles. The apparent viscosity of the nanoparticle solutions and RBC suspensions in the presence and absence (the control) of nanoparticles were measured using a rotational viscometer Contraves Low Shear 30 (LS 30) at a steady flow at shear rates from 0.0237 to 94.5 s-1 and temperature 37 C. A method, based on the measurement of dielectric properties of dispersed systems in Couette viscometric blood flow was applied. A concurrent measurement system and data acquisition system implied into the Contraves LS 30 were used to quantify the electrical conductivity. The main advantage of this technique is that blood is subJected to a uniform shearing field in a Couette rheometric cell as well as the information about the mechanical and electrical properties of the fluid is obtained in parallel. The results show that rheological and electrical properties of the nanoparticle solutions and RBC suspensions, namely their electrical conductivity and apparent viscosity, are dependent on the shear rates, shape, concentration and molecular weight of the polymers. Key

Cite this publication as follows:
Antonova N, Koseva N, Kowalczuk A, Riha P, Ivanov I: Rheological and electrical properties of polymeric nanoparticle solutions and their influence on RBC suspensions, Appl. Rheol. 24 (2014) 35190.

This paper presents the development of a vane rheometer to estimate mortar plastic viscosity and yield stress. The rheological parameters were developed from measurements using a procedure to convert the vane torque and rotational velocity data into shear stress versus shear rate relationships. The used procedure considered the locally sheared material as a Bingham fluid and computed the characteristic shear rate from Couette analogy. The apparatus was tested with three experimental programs in which many rheological parameters of mortar compositions were calculated. The obtained results validated the rheometer test procedure and confirmed that the test results are reproducible.

Cite this publication as follows:
Soualhi H, Kadri E, Ngo T, Bouvet A, Cussigh F, Kenai S: A new vane rheometer for fresh mortar: development and validation , Appl. Rheol. 24 (2014) 22594.

Blood vessels have been modeled as non-porous structures that are permeable to solutes mixed in the blood. However, the use of non-physiological boundary conditions in numerical simulations that assume atmospheric pressure at the outlet does not illustrate the actual structural physics involved. The presence of pores in the wall influences wall deformation characteristics, which may increase the risk of rupture in specific conditions. In addition, the formation of secondary flows in a curved blood vessel may add complications to the structural behavior of the vessel walls. These reservations can be addressed by a fluid structure interaction-based numerical simulation of a three-dimensional aortic arch with increased physiological velocity and pressure waveforms. The curvature radius of the arch was 30 mm with a uniform aorta diameter of 25 mm. A one-way coupling method was used between physics of porous media flow and structural mechanics. A comparison of results with a non-porous model revealed that the approximated porous model was more prone to hypertension and rupture. Similarly, the secondary flows found to be an important indicator for the vascular compliance that forced the outer aortic region to experience the largest deformation. Consequently, it is very important to use actual physiological situations of the blood vessels to reach a diagnostic solution.

Cite this publication as follows:
Cheema TA, Kim GM, Lee CY, Hong JG, Kwak MK, Park CW: Characteristics of blood vessel wall deformation with porous wall conditions in an aortic arch, Appl. Rheol. 24 (2014) 24590.

This work contributes to general theoretical aspects of yield stress fluids with significance for practical phenomenological material modeling. It introduces a terminology so that the material class .yield stress fluid. is defined and can be distinguished from the terms .solid. and .liquid.. This new material classification is based on two criteria, the equilibrium relation and the flow function. In line with this terminology, an experimental procedure for classifying the material behavior is presented. The second key aspect of this paper is a discussion on the proper definition of the term .viscosity.. The benefit of the differential viscosity over the dynamic viscosity in case of non-Newtonian fluids in general is worked out. This is shown by the most elementary yield stress fluid, the friction element, because it is the basis of the yield stress concept. Its constitutive equations are given for positive as well as negative strain rates and are also able to represent the preyield behavior. The theory presented in this article is also applied to the Maxwell, Kelvin-Voigt, and Bingham element to demonstrate the working principle.

Supplementary Information is contained as an attachment to the reprint-pdf.

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Boisly M, Kastner M, Brummund J, Ulbricht V: General aspects of yield stress fluids - Terminology and definition of viscosity, Appl. Rheol. 24 (2014) 14578.

Mechanical properties of various technological materials at large deformations are proposed to characterize by means of some generalized parameters obtained at large oscillation strains but not related to any definite rheological equations. The base for the analysis is the LissaJous- Bowditch figures in two coordinate systems - "stress - deformation" and "stress derivative with respect to the phase angle - deformation". An area of the first of these figures provides the well known integral estimation of dissipative losses in the deformation cycle while the second one presents the new integral measure of the matter's elasticity. The correlation between the proposed integral estimations of the "averaged" dynamic modulus and the values found in using Fourier and Chebyshev series was demonstrated. This integral method was applied for three suspensions of various types. The obtained results allowed for viewing the type of non-linearity: pseudo-plasticity or dilatancy, stiffening or softening, as functions of deformation.

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Ilyin S, Kulichikhin V, Malkin A: Characterization of material viscoelasticity at large deformations, Appl. Rheol. 24 (2014) 13653.

Impregnation of organic liquid electrolytes in conductive powders is of maJor importance in the field of energy storage devices such as batteries or super-capacitors. Impregnation during mixing and processing operations becomes usual for practical reasons and requires a better understanding of the changes of the rheological behavior of the mix. In this paper, the impregnation of propylene carbonate (PC) and dimethyl sulfoxide (DMSO) in activated carbon (AC) and carbon black (CB) was studied by using an internal mixer. Monitoring of the torque of the filler/liquid blend as a function of the amount of liquid fed in the mixing chamber, enables to detect the transition from the solid friction of the dry powder to the lubricated liquid (or viscous) behaviour of the concentrated paste of wetted powder. The results were compared with data obtained by conventional nitrogen adsorption porosimetry combined with the knowledge of the molecular diameter of the liquids. A characteristic change was observed as soon as the liquid completely fills the porosity of the filler. Both tested liquids (DMSO and PC) impregnate more carbon black and the take-up rate is slightly higher for DMSO in comparison to PC because, as a polar liquid, DMSO has a better interaction with both fillers.

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Akkoyun M, Carrot C, Blottiere B: On the use of an internal mixer to study the impregnation of carbon fillers by organic liquids, Appl. Rheol. 24 (2014) 13487.

We present a study of the structural and thermomechanical properties of lyotropic phase in the quasi ternary system made of Cetylpyridinium chloride (CPCl)/hexanol/salt water (0.9% by mass) with and without cobalt microparticles. Phase transition temperatures of the structural sequence isotropic L1/nematic calamitic Nc,/hexagonal H have been determined by differential scanning microcalorimetry. Temperature induced developable domains in hexagonal phase H and disclinations in calamitic nematic phase Nc were observed in crossed polar optical microscopy in confined geometry. A rheological study of calamitic nematic phase Nc highlighted structuring effect of cobalt microparticles from a concentration of 2% to be demonstrated by an increase in viscosity and viscoelastic moduli. This could be explained by a stabilization of disclinations.

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Ponton A, Meyer C, Foyart G, Aymard L, Djellab K: Structural and thermomechanical investigation of lyotropic liquid crystal phases doped with monodisperse microparticles, Appl. Rheol. 24 (2014) 14147.

Cite this publication as follows:
Rubio-Hernandez F, Gomez-Merino A, Velazquez-Navarro J, Parras L: 4th Iberian Meeting on Rheology. Fundamental and Applied Rheology (IBERO 2013), Appl. Rheol. 23 (2013) 374.

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Czerwinska J: 12th Swiss Soft Days (SSD 12), Appl. Rheol. 23 (2013) 375.

This study addresses the Taylor-Galerkin/pressure-correction solution of industrial high-speed reverse roller coating flow associated with thin-film paint-coatings of strip-steel. Novel aspects lie in the inclusion of the dynamic wetting line and flow analysis due to surface tension and inelastic rheology effects, via shear-thinning and lowering high shear viscosity levels. The main aim of the study is to predict the zonal flow influences by examining viscous flow structures around the meniscus, nip and wetting line regions, conveyed via streamline and shear rate patterns, surface distributional lift and localised nip-pressures. The maJority of this study focuses on the secondary nip-vortex and its influences on the contact point and dynamic wetting line. This aspect of the flow provides the driving mechanism for the onset of instabilities, which governs the entire process and tends to determine the consistency of the film thickness at the outflow. Positive peak-pressures tend to increase with decrease in nip-gap size. At low nip-gap size, negative peak pressures are observed around the substrate-wetting line contact region. At higher speed-ratios, positive peak pressures are seen to increase with less recirculation apparent around the contact zone. Significantly and upon surface tension increase, the dynamic wetting line is sucked further inwards towards the nip-gap, stimulating a localised wetting line-foil third vortex structure, which causes an apparent reduction in film-leakage thickness.

Cite this publication as follows:
Echendu S, Tamaddon-Jahromi H, Webster M: Modelling Reverse Roll Coating flow with dynamic wetting lines and inelastic shear thinning fluids, Appl. Rheol. 23 (2013) 62388.

Production in reservoirs located in deep and ultra-deep water that contain waxy crude oils faces a huge obstacle imposed by the low temperatures of the environment. When the waxy crude oil is subJected to a temperature below the Gelation Temperature, as in the case investigated in the present work, it exhibits a variety of non-Newtonian features: elasticity, plasticity, viscous effects, and time-dependency, which renders to this material a highly complex behavior. A crucial feature that is frequently ignored when the determination of the yield stress is being carried out, is the time-dependency nature of these materials. We demonstrate how significantly different values of yield stress can be obtained if this character of the material is neglected. We use the asphaltenes properties as inhibitors of wax formation and propose a protocol to capture yield-stress parameters. One important conclusion is that waxy crude oils can be classified as apparent-yield-stress fluids, and not (true-) yield-stress materials, with the presence of a dynamic and a static yield-stresses.

Cite this publication as follows:
Soares EJ, Thompson RL, Machado A: Measuring the yielding of waxy crude oils considering its time-dependency and apparent-yield-stress nature, Appl. Rheol. 23 (2013) 62798.

Cite this publication as follows:
Handge UA: Joint Symposium of the German Rheological Society and the Polymer Processing Society (PPS-29) Fundamental and Applied Rheology, Appl. Rheol. 23 (2013) 310.

Cite this publication as follows:
Madsen CG, Abo J, Featherston DW, Baldursdottir S: Rheology: A cross-disciplinary technology evolving to take on new challenges (22nd Nordic Rheology Conference 2013), Appl. Rheol. 23 (2013) 309.

Polysaccharides provide high potential to be used as rheology modifying admixtures in mineral binder systems for the construction industry such as concrete or mortar. Since superplasticizers have become state of technology, today, concrete is more and more adJusted to flowable consistencies. This often goes along with the risk of segregation, which can be effectively avoided by adding stabilising agents supplementary to superplasticizers. Stabilising agents are typically based on polysaccharides such as cellulose, sphingan gum, or starch. Starch clearly distinguishes in its effect on rheology from other polysaccharides, mainly due to the strong influence of amylopectin on the dispersion and stabilisation of particles. Based on rheometric investigations on cementitious and limestone based dispersions with different volumetric water to solid ratios, the mode of operation of modified potato starch is explained in comparison to a sphingan gum. It is shown that the stabilising effect of starch in a coarsely dispersed system is mainly depending upon the water to solid ratio and that above a certain particle volume threshold starch mainly affects the dynamic yield stress of dispersions, while plastic viscosity is affected only to a minor degree. Sphingans operate more independent of the particle volume in a coarsely dispersed system and show significantly higher effect on the plastic viscosity than on the yield stress. In systems incorporating superplasticizers, influences of both stabilising agents on yield stress retreat into the background, while both observed polysaccharides maintain their effect on the plastic viscosity.

Cite this publication as follows:
Schmidt W, Brouwers HJH, Kuhne H-C, Meng B: The working mechanism of starch and diutan gum in cementitious and limestone dispersions in presence of polycarboxylate ether superplasticizers, Appl. Rheol. 23 (2013) 52903.

The shear thickening behavior of concentrated suspensions can be exploited to dissipate energy during impact or shear loading. To preserve the consistency of the thickening behavior in practical applications, particle concentration, and dispersion should be kept within very close bounds over time. In this article, we analyze the influence of the processing methods and storage conditions on the rheological properties of shear thickening fluids (STF) based on monodisperse suspensions of silica particles in polyethylene glycol. Particle dispersion linked to processing method and time strongly influences the value of the critical shear rate and storage in contact with air and humidity is responsible for a change in particle concentration. Encapsulating the suspensions in silicone is proposed as a solution to preserve their rheological properties over time.

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Soutrenon M, Michaud V, Manson JAE: Influence of processing and storage on the shear thickening properties of highly concentrated monodisperse silica particles in polyethylene glycol, Appl. Rheol. 23 (2013) 54865.

The main obJective of this study is to get insight into the dynamic behavior of viscoplastic drop in impingement process in which the Capillary number is greater than one. In numerical analysis, Volume Of Fluid (VOF) approach was used for capturing the liquid-gas interface. Two different drop shapes (spherical and tear shapes) were used to investigate the drop morphology in an impingement process. According to the results, the numerical results concerning the tear shape drop showed proper agreement with experimental reports (mean deviation of 16 %) in different impact velocities. The flow field was discussed during the impact process in terms of its effect on apparent viscosity and spreading length. Influence of contact angle, consistency, power law index, and surface tension variations on spreading parameter (ratio of contact diameter on the substrate to equivalent initial drop diameter) were investigated. Furthermore, three different rheological models (consisting of Herschel-Bulkley, Casson, and Robertson-Stiff) were employed to study the effects of rheological models on simulation outcomes.

Cite this publication as follows:
Noroozi S, Tavangar S, Hashemabadi S: CFD Simulation of Wall Impingement of Tear Shape Viscoplastic Drops Utilizing OpenFOAM, Appl. Rheol. 23 (2013) 55519.

Viscosity measurements were performed in water/AOT (sodium bis(2-ethylhexyl) sulfoccinate)/isooctane microemulsions as a function of temperature between 25 C and 55 C, molar ratio Wo = water/AOT ranging from 3 to 45 and three values of AOT/isooctane volume fractions (Φm = 0.1, 0.15, and 0.2). It was shown that microemulsions behaved as Newtonian fluids in the studied range of shear rate. For a critical molar ratio, Woc, the corresponding viscosity, ηoc, was shown to be constant with temperature but dependent on the micellar concentration. For Wo < Woc, the solutions behaved as simple fluids and the temperature dependence of viscosity was described by an Arrhenius law. The total activation energy was found to be dependent on W with a maximum for Wo = 5. A correlation between the microscopic structure of the reverse micelles and the total activation energy was proposed. However, a complex fluid behavior was observed for Wo > Woc, where the viscosity increased with temperature. For some values of Wo, the viscosity reached a maximum, which could be explained by attractive interdroplet interactions and formation of droplet clusters.

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Guettari M, BenNaceur I, Kassab G, Ponton A, Tajouri T: Temperature and concentration induced complex behavior in ternary microemulsion, Appl. Rheol. 23 (2013) 44966.

A commercial epoxy resin system was tested under several different mixing conditions with viscometer and rheometer apparatuses. In each test, two portions of the same resin, prepared at different times, were mixed and their Joint behavior was analysed. The differences between the behavior of this blend and the neat (unmixed) resin after the mixing point were, then, critically assessed. Both the preparation time gap and the mixing ratio of the two portions coherently affected the overall blend behavior. However, the commonly accepted linear combination of the contributions of the portions of resin with different degrees of cure, usually employed to describe the Joint behavior, was not applicable for the entire time interval after mixture.

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Faria H, AndradePires FM, TorresMarques A: Identification of the Combined Rheology of Mixtures of Epoxy Resins with Different Initial Curing States, Appl. Rheol. 23 (2013) 42413.

Back extrusion represents one of the cheapest experimental methods to determine rheological characteristics of studied fluids, and simultaneously minimise their disruption in comparison with conventional rotational rheometers. This method is based on plunging a circular rod into an axisymmetrically located circular cup containing the experimental sample. Formerly this method has, among other uses, been successfully applied to determinations of parameters appearing in power-law, Bingham and Herschel-Bulkley fluids. The aim of this contribution is to present a sufficiently simple user-friendly procedure for determining individual rheological parameters appearing in the Vocadlo model (sometimes called the Robertson-Stiff model) - yield stress, consistency parameter and flow behaviour index.

Cite this publication as follows:
David J, Filip P, Kharlamov A: Back extrusion of Vocadlo-type fluids, Appl. Rheol. 23 (2013) 45366.

Currently more and more researches have been performing concerning the numerical simulation of the behavior of fresh concrete during pumping or formwork filling. Adequate implementation of the rheology properties of fresh concrete is a determinant key to obtain realistic simulations. However, in many cases, the rheological parameters of the fresh concrete as determined by rheometers are not sufficiently accurate. The common principle of all the rheometers is not to measure directly the rheological parameters of concrete but to measure some basic physical parameters (torque, velocity, pressure, ...) that that in some cases allow the calculation of the rheological parameter in terms of fundamental physical quantities. Errors can be caused by undesired flow phenomena which are not taken into the prediction formulas and by the inaccurate prediction formulas themselves. This is directly related to the poor calibration of the rheometer that cannot cover all ranges of materials. This paper investigates the calibration of the Tattersall MK-II rheometer by performing the numerical simulation for a tremendous range of concrete flowing in the rheometer, using computational fluid dynamics (CFD). This allows to quickly and accurately obtain the rheological properties of fresh concrete, which can then be used consistently for further flow simulations. This method can be applied for all types of rheometer.

Cite this publication as follows:
Le HD, DeSchutter G, Kadri E, Aggoun S, Vierendeels J, Tichko S, Troch P: Computational fluid dynamics calibration of Tattersall MK-II type rheometer for concrete, Appl. Rheol. 23 (2013) 34741.

Cite this publication as follows:
Zelko J, Prakash JR, Duenweg B: Fluid-Structure Interactions in Soft-Matter Systems: From the Mesoscale to the Macroscale (Prato, 2012), Appl. Rheol. 23 (2013) 124.

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Ge W: Turbulent Drag Reduction by Surfactant Additives (FC Li, B Yu, JJ Wei, Y Kawaguchi), Appl. Rheol. 23 (2013) 84.

We discuss the possibility of using penetrometry technique for measuring the yield stress of concentrations made of grains immersed in a colloidal phase, such as concrete or muds. In that aim we used model materials made by suspending glass beads at different concentrations in a kaolin-water paste. We then show that a uniform shear stress develops along the obJect (plate or cylinder) beyond the entrance length. This shear stress plotted versus the obJect velocity exhibits a shape similar to the flow curve of the material determined from rheometry. For materials exhibiting the typical flow curve of a simple yield stress fluid, i.e. at bead concentrations smaller than 30 %, the stress associated with an inflection point located at low velocities of this curve appears to correspond to the material yield stress. At larger concentrations of beads the suspensions have a more complex behaviour likely affected by its granular nature at a local scale and the possibility of migration or frictional effects, so that neither conventional rheometry nor penetrometry provide relevant data. We conclude by describing two practical penetrometry techniques for precisely measuring the yield stress of simple pastes.

Cite this publication as follows:
Tikmani M, Boujlel J, Coussot P: Assessment of penetrometry technique for measuring the yield stress of muds and granular pastes, Appl. Rheol. 23 (2013) 34401.

Cite this publication as follows:
Thomas S, Kalarikkal N, Joy J: Third International Conference on Natural Polymers (ICNP 2012), Appl. Rheol. 23 (2013) 59.

This paper discusses the rheological properties of different contents of a commercially available Southern African clay, Eccabond fine (EBF), modified with hexadecyl trimethyl ammonium bromide, and Cloisite 15A (C15A), modified with dimethyl dehydrogenated tallow quaternary ammonium chloride dispersed in silicone oil. Focused-ion beam scanning electron microscopy shows that both C15A and EBF clays have sheet-like morphologies, but the sheets are more compact in the case of EBF clay. The rheological behavior of different suspensions was characterized by using a rheometer. The EBF suspensions behaved like Bingham fluids and also exhibited higher degrees of viscoelasticity than the C15A suspensions. The Casson model used to calculate the data of the yield stresses for the EBF suspensions was found to fit quite well with the flow curve results. The EBF suspensions obeyed the Schwarzl relation, in which the relaxation modulus (G(t)) illustrated a plateau-like behaviour for EBF suspensions compared to the C15A suspensions.

Cite this publication as follows:
Hato MJ, Pillai SK, Choi HJ, Zhang K: The rheology of non-aquoeous suspension of modified eccabond fine (EBF) clay, Appl. Rheol. 23 (2013) 34870.

The flow of complex fluids is routinely encountered in a variety of industrial manufacturing operations. Some of these operations use rheological methods for process and quality control. In a typical process operation small quantities of the process fluid are intermittently sampled for rheological measurements and the efficiency of the process or the quality of the product is determined based on the outcomes of these measurements. The large number of sample-handling steps involved in this approach cost time and cause inconsistencies that lead to significant variability in the measurements. These complications often make effective process/ quality control using standard rheometric techniques difficult. The effectiveness of control strategies involving rheological measurements can be improved if measurements are made online during processing and sampling-steps are eliminated. Unfortunately, online instruments capable of providing sufficiently detailed rheological characterisation of process fluids have been difficult to develop. Commercially available online instruments typically provide a single measurement of viscosity at a fixed deformation rate. This dependence on a single pre-determined shear rate restricts these instruments from identifying changes in the product or the process, especially if the viscosity at the pre-determined shear rate remains unaltered during these changes. We introduce an Online Rheometer (OLR) that uses small amplitude oscillatory squeeze flow to measure the viscoelastic properties of process fluids in-process and in real time under typical processing conditions. We demonstrate that with an appropriate measuring geometry and amplitude of oscillation, the frequency response of typical non-Newtonian fluids can be accurately measured in a process pipe. We also compare our results with other techniques that are typically used for process rheometry, critically evaluating the utility of the OLR technology for advanced process and quality control.

Cite this publication as follows:
Konigsberg D, Nicholson TM, Halley P, Kealy TJ, Bhattacharjee PK: Online process rheometry using oscillatory squeeze flow, Appl. Rheol. 23 (2013) 35688.

This work evaluates the impact of using bauxite residue (BR) as filler addition in cementitious compositions, during the early ages of transformation from the viscous fluid phase to an elastic solid. Chemical reaction and consolidation (physical phenomena of hardening) were also correlated. The chemical reaction rate was accompanied using isothermal calorimetry and the consolidation measured using oscillatory rheometry (quantifying the storage modulus - G' and relating with yield stress, σ0). The results show that BR accelerates the cement hydration reaction, but in pastes with pure cement, consolidation was faster, showing a distinct effect on the fluid-solid transition.

Cite this publication as follows:
Romano RCdO, Liberato CC, Montini M, Gallo JB, Cincotto MA, Pileggi RG: Evaluation of transition from fluid to elastic solid of cementitious pastes with bauxite residue using oscillation rheometry and isothermal calorimetry, Appl. Rheol. 23 (2013) 23830.

Three maJor hydrogenated castor oil crystal morphologies have been observed: fiber, rosette and irregular crystal. Due to the difficulty in obtaining samples with a single crystal morphology, rheological studies of suspensions containing mixtures of the three morphologies in an aqueous solution have been undertaken. The viscometry of dilute suspensions has shown that the magnitude of intrinsic viscosity is dominated by the fraction of a crystal morphology type, i.e. fiber > rosette > irregular crystal. A modified Farris model was fitted to the rheology data for mixtures of crystal morphology with interacting particles. A yield stress exists for concentrated suspensions followed by a shear thinning behavior with the increase of shear rate. A power-law relation has been found between yield stress and total particle volume fraction, and a constant exponent of 1.5 has been obtained regardless of crystal morphology.

Cite this publication as follows:
Yang D, Hrymak A: Rheology of Aqueous Dispersions of Hydrogenated Castor Oil , Appl. Rheol. 23 (2013) 23622.

The obJective of this paper is to present the results of a research about the effect of mineral additions and specific lightweight aggregates obtained from wastes materials (crushed EPS and cork) on the rheological properties of renderings mortars. Four series of mortar formulations were prepared. Each series was composed by four mortars mixes with different mineral additions: hydrated lime, glass powder, tungsten mine waste mud, and metakaolin. The proportions of the mortars expressed in terms of apparent volume of cement, mineral addition and sand was 1:1:5. Flowability of mortar was measured using a standard flow table test. The density and the water retention capacity of mortars were also determined. The mortar rheological parameters were evaluated using a rheometer. The results show that the mortar yield stress is strongly influenced by the water amount, binder fineness and mineral addition nature. The mortars plastic viscosity is also influenced by the nature of mineral addition and the partial replacement of sand by EPS aggregates introduce incongruent values, caused by the segregation, in the mortar yield stress, whereas, the cork aggregates is responsible by the yield stress reduction.

Cite this publication as follows:
PereiradeOliveira LA, CastroGomes JP, Nepomuceno M: The influence of wastes materials on the rheology of rendering mortars, Appl. Rheol. 23 (2013) 15505.

Cite this publication as follows:
Goh A, Hassell D, Jaafar A: Institute of Materials Malaysia (IMM) 1st Rheology Symposium 2012, Appl. Rheol. 22 (2012) 347.

This paper describes the development of a rapid rheological method for the characterization of functionalized citrus pulp fibers by high pressure homogenization. The suspension rheology of the fibers differ significantly depending on the applied processing conditions, making it critical to have quick and robust quality control tools in place. The weak polyelectrolyte nature of the fibers was considered in order to define the adequate solvent conditions for the rheological evaluation of the suspensions. Secondly, an improved dispersion method using ethylene glycol was developed in order to ensure optimal hydration of the dry fiber. The effect of fiber concentration was then studied both under steady-shear and oscillation tests. The dry matter concentration for the rapid rheological method was set at 4 w/w% above the experimental critical concentration or percolation threshold.

Cite this publication as follows:
Debon S, Wallecan J, Mazoyer J: A rapid rheological method for the assessment of the high pressure homogenization of citrus pulp fibres, Appl. Rheol. 22 (2012) 63919.

This paper discusses the influence of fat type in the structure of ice cream, during its production by means of rheo-optical analysis. Fat plays an important part in the ice cream structure formation. It's responsible for the air stabilization, flavor release, texture and melting properties. The obJective of this study was to use a rheological method to predict the fat network formation in ice cream with three types of fats (hydrogenated, low trans and palm fat). The three formulations were produced using the same methodology and ratio of ingredients. Rheo-optical measurements were taken before and after the ageing process, and the maximum compression force, overrun and melting profile were calculated in the finished product. The rheological analysis showed a better response from the ageing process from the hydrogenated fat, followed by the low trans fat. The formulation with palm fat showed greater differences between the three, where through the rheological tests a weaker destabilization of the fat globule membrane by the emulsifier was suggested. The overrun, texture measurements and meltdown profile has shown the distinction on the structure formation by the hydrogenated fat from the other fats.

Cite this publication as follows:
Su F, Lannes SCS: Rheological evaluation of the structure of ice cream mixes varying fat base, Appl. Rheol. 22 (2012) 63871.

Simulations are performed to investigate the flow of a shear-thinning, non-Newtonian fluid in a collapsed elastic tube and comparisons are made with experimental data. The fluid is modeled by means of the Bird- Carreau viscosity law. The computational domain of the deformed tube is constructed from data obtained via computer tomography imaging. Comparison of the computed velocity fields with the ultrasound Doppler velocity profile measurements show good agreement, as does the adJusted pressure drop along the tube.s axis. Analysis of the shear rates show that the shear-thinning effect of the fluid becomes relevant in the crosssections with the biggest deformation. In fact, the maximum shear rate is about a factor of thirty larger than its corresponding maximum value in the undeformed tube, and the viscosity is reduced by a factor of two. The effect of the shear-thinning behavior has also been compared with identical simulations carried out for a Newtonian fluid.

Cite this publication as follows:
Tanner FX, Al-Habahbeh AA, Feigl KA, Nahar S, Jeelani SJA, Case WR, Windhab EJ: Numerical and Experimental Investigation of a Non-Newtonian Flow in a Collapsed Elastic Tube, Appl. Rheol. 22 (2012) 63910.

Cite this publication as follows:
Taj D, Savin T: International Workshop on Nonequilibrium Thermodynamics (IWNET 2012) and 3rd Lars Onsager Symposium, Appl. Rheol. 22 (2012) 274.

The T-bar rheometrical tool (Brookfield Engineering Laboratories, Inc.) is a slender rod which is placed in a material and rotated horizontally about its short axis by a vertical shaft. The torque on the shaft from laminar flow of material around the rod is determined by the material.s rheological properties. T-bar experiments for a Newtonian liquid are shown to agree closely with existing theory. For yield stress materials an approximation is derived for the torque on a rotating T-bar which is supported by experiments on a range of materials. The torque for very slow rotational speed is insensitive to boundaries beyond a few T-bar diameters and is shown to correlate with the material.s yield stress and other non-Newtonian parameters. A stepdecrease in torque for each half-revolution of the T-bar was shown by some materials and possible origins of this effect are discussed.

Cite this publication as follows:
Anderson VJ, Meeten GH: Interpretation of T-bar tool measurements for yield stress materials, Appl. Rheol. 22 (2012) 55370.

Control of food or bolus flow properties is part of several strategies to address aspiration pneumonia in dysphagic patients. An important alternative is the use of prescribed ready-to-use (RTU) oral nutritional supplements (ONS) specially designed for the nutritional support at different stages of dysphagia. However, it is clear that there are significant differences among products designed for the same level or stage of dysphagia. On the other hand, videofluoroscopy has become a key technique for the evaluation of swallowing and, thus, dysphagia. In this study, a new approach for designing RTU ONS products, specifically spoon-thick consistency products, has been carried out. The scientific approach has been based, first, on the characterization of the rheological properties of a standard barium-based commercial product used in videofluoroscopy studies and, then, matching the viscous flow properties of the RTU ONS product accordingly, by taking into consideration both formulation and process conditions. The results obtained clearly suggest that it is possible to obtain an excellent viscous flow behaviour similarity of both swallow barium test feed and RTU ONS produced at industrial scale. In this sense, both linear viscoelasticity properties and non-linear relaxation modulus have to be optimised to obtain the rheological similarity previously mentioned.

Cite this publication as follows:
Brito-delaFuente E, Staudinger-Prevost N, Quinchia LA, Valencia C, Partal P, Franco JM, Gallegos C: Design of a new spoon-thick consistency oral nutrition supplement using rheological similarity with a swallow barium test feed, Appl. Rheol. 22 (2012) 53365.

Cite this publication as follows:
Wagner C: Joint Focus Session Rheology of the German Rheological Society (DRG) together with the German Physical Society (DPG), Appl. Rheol. 22 (2012) 213.

In-vitro small intestinal flow characteristics of a shear thinning fluid are investigated by transient '2-wave'-squeezing of an elastic tube under different speeds of peristalsis. Such peristaltic flow is the essential physiological transport mechanism in the gastro-intestinal tract. The peristalsis involves both expansion and contraction type of flow (crest and trough of a wavelength). We met the challenge of implementing the UVP technique for monitoring the velocity fields during appropriate peristaltic propulsion of a shear thinning fluid through an elastic tube (in vitro modeled small intestine). The higher wave speed of peristalsis results in higher magnitude of back flow velocity (negative) both in the wave crest and trough regions with positive value being adJacent to the tube wall. In addition, the approximated wall shear rates at the wave trough are also found to be higher than those in the wave crest. The higher value of back flow is expected to be responsible for the improved mixing and convection leading to higher mass transport through the intestinal wall. The measured pressure difference between crest and trough of a peristaltic wave increased, as the wave speed got faster. However, the crest region showed a higher pressure compared to the trough region since the magnitude of back flow velocity in the wave trough is found to be much higher compared to that in the wave crest.

Cite this publication as follows:
Nahar S, Jeelani SAK, Windhab EJ: Peristaltic flow characterization of a shear thinning fluid through an elastic tube by UVP, Appl. Rheol. 22 (2012) 43941.

Ultrasonic Velocity Profiling (UVP) is a powerful technique for velocity profile measurements in research and engineering applications as it is the only available method that is cost-effective, relatively easy to implement and applicable to opaque fluid suspensions, which are frequently found in industry. UVP can also be combined with Pressure Drop (PD) measurements in order to obtain rheological parameters of non-Newtonian fluids by fitting theoretical rheological models to a single velocity profile measurement. The flow properties of complex fluids are almost exclusively obtained today using commercially available instruments, such as conventional rotational rheometers or tube (capillary) viscometers. Since these methods are time-consuming and unsuitable for real-time process monitoring, the UVP+PD methodology becomes a very attractive alternative for in-line flow behavior monitoring as well as quality control in industrial applications. However, the accuracy of the UVP+PD methodology is highly dependent on the shape and magnitude of the measured velocity profiles and there are still a few problems remaining with current instrumentation and methods in order to achieve the robustness and accuracy required in industrial applications. The main obJective of this research work was to optimize an UVP+PD system by implementing new transducer technology and signal processing techniques for more accurate velocity profile measurements as well as rheological characterization of complex fluids under industrial/realistic conditions. The new methodology was evaluated in two different pipe diameters (22.5 and 52.8 mm) and tested with three different non-Newtonian fluids in order to obtain a wide range of rheological parameters. Results were also compared to conventional rotational rheometry and tube viscometry. It was found that rheological parameters obtained from accurate velocity data across the pipe radius, especially close to pipe walls where the velocity gradient is high, showed better agreement to conventional rheometry than when compared to results obtained using profiles measured with conventional UVP instrumentation and commercial software (Met- Flow SA Version 3.0). The UVP+PD method is now more robust and accurate. The main challenge remaining is to successfully implement a complete non-invasive system in industrial processes that is able to achieve real-time and accurate complex flow monitoring of non-Newtonian fluid suspensions.

Cite this publication as follows:
Kotze R, Wiklund J, Haldenwang R: Optimization of the UVP+PD rheometric method for flow behavior monitoring of industrial fluid suspensions, Appl. Rheol. 22 (2012) 42760.

Measurements of the viscosity of non-Newtonian fluids and suspensions having a solid volume fraction of about 30% or more is of maJor interest from an industrial point of view. Cement paste and cement grouts for inJection grouting applications, with water to cement ratios typically in the range of 0.4 and 0.6 - 0.8 by weight, are two examples of industrial fluid systems. Few in-line techniques are available on the market that can be used for these fluid systems and under realistic field conditions. The so-called UVP+PD in-line rheometry method combining the Ultrasound Velocity Profiling (UVP) technique with Pressure Difference (PD) measurements is a promising new tool for industrial applications. This paper presents an initial pre-study that aims to demonstrate the feasibility of the UVP+PD method using cement grouts for process monitoring and control of grouting applications under realistic field conditions. The UVP+PD method was tested and found successful for continuous in-line measurements of concentrated micro cement-based grouts with water/cement ratios of 0.6 and 0.8. The test set-up consisted of a combination of an experimental .flow loop. and a conventional field grouting rig - UNIGROUT, from Atlas Copco. The rheological properties were determined, directly in-line and the parameters obtained were subsequently compared with off-line measurements using a conventional rotational rheometer.

Cite this publication as follows:
Wiklund J, Rahman M, Hakansson U: In-line rheometry of micro cement based grouts . a promising new industrial application of the ultrasound based UVP+PD method, Appl. Rheol. 22 (2012) 42783.

The in-line rheometer concept based on the combination of the ultrasonic velocity profiling (UVP) technique and pressure difference (PD) measurements was utilized for investigating the influence of particle concentration and size distribution on the rheology of particulate suspensions in pipe flow under realistic industrial process conditions. Well defined model suspensions were used, consisting of 11 mm and 90 mm diameter polyamide particles suspended in rapeseed oil at concentrations ranging from 1 to 25 % by volume. The variation of concentration and particle size distribution had the expected effects on the shear viscositiy of the investigated unimodal and bimodal suspensions. The in-line results showed that the investigated suspensions exhibit Sisko flow behavior and demonstrated that the UVP+PD method can be used to determine the flow behavior of complex fluids and suspensions, even at high solid concentrations, under industrial conditions in-line. The obtained inline results were in good agreement with measurement data obtained using a conventional rotational controlled- stress rheometer. Limitations of commercially available transducer technology were identified and other possible sources of inaccuracy of the UVP+PD method were investigated. Several improvements of the UVP+PD measurement method were proposed.

Cite this publication as follows:
Wiklund J, Birkhofer B, Jeelani S, Stading M, Windhab EJ: In-line rheometry of particulate suspensions by pulsed ultrasound velocimetry combined with pressure difference method, Appl. Rheol. 22 (2012) 42232.

Cementitious pastes prepared with air-entraining admixtures (AEA) are very sensitive to mix procedures and environmental conditions. Some of the effects of AEA on the properties of cementitious material are discussed in literature, although for the most part, only in the hardened state. However, the impact temperature has on air-incorporation during the early age stages and on consolidation has been little investigated and as such, is the obJective of this work. Thus, pastes formulated with Portland cement and air-entraining admixtures are evaluated in this work with a focus on the role temperature plays in the early age behavior. The results show that air-incorporation was affected by environmental conditions which caused changes in the kinematic viscosity and rate of consolidation.

Cite this publication as follows:
deOliveiraRomano RC, Pileggi RG: Temperature's role in the rheological behavior of cementitious pastes prepared with air-entraining admixtures, Appl. Rheol. 22 (2012) 24333.

The principle of silicate layer reinforcement in a polymer matrix is known as the formation of a 3D network of single layers. Nevertheless there is still a lack of knowledge about the physical ageing of nanocomposites respectively the stability of this network over time. As most of the nanocomposite applications have a more or less long-term shelf life respectively storage time, the investigation of the storage-time dependent behavior of the layered 3D structure in a polymer matrix is of maJor interest. In this study, the rheological (shear and elongational) properties of different polypropylene nanocomposites were measured using a cone-plate rheometer and a Rheotens apparatus. To evaluate the structural stability over time, the samples were measured immediately after processing and after defined periods (18 and 36 months) stored under constant conditions. Furthermore the network structure was determined using XRD and TEM measurements. The results show, that, depending on the clay rate and especially the degree of exfoliation, the rheological properties are changing significantly. Thereby chain splitting caused by photo-oxidative degradation, leading to a loss in molecular weight, as well as a weakened 3D network by reverse diffusion of the polymer chains out of the clay gallery and/or reagglomeration of the nanoparticles are the two main factors.

Cite this publication as follows:
Laske S, Witschnigg A, Mattausch H, Kracalik M, Pinter G, Feuchter M, Maier G, Holzer C: Determining the ageing of polypropylene nanocomposites using rheological measurements, Appl. Rheol. 22 (2012) 24590.

Cite this publication as follows:
Cidade T, Sousa I, Franco JM: Iberian Meeting on Rheology - Rheology Trends: From Nano to Macro Systems (Ibero 2011): From nano to macro systems (Ibereo 2011), Appl. Rheol. 22 (2012) 44.

Cite this publication as follows:
Cheneler D: Colloidal Suspension Rheology (J. Mewis, N. J. Wagner), Appl. Rheol. 22 (2012) 12.

Cite this publication as follows:
Mothe CG: 1st Brazilian Congress of Rheology (CBR 2011), Appl. Rheol. 21 (2011) 364.

Viscoelastic properties are traditionally measured using sophisticated instrumentation, and the high cost of these rheometers may limit utility. This research attempts to enable viscometers that can provide a torque-time response, with vane attachment and a recommended cup size, to measure viscoelastic properties. Phase angles and shear moduli of model systems (gelatin and polyacrylamide gels) were calculated using torque-time response and deformation zone concept. The methods were applied to data obtained from Brookfield YR-I viscometer and the calculated values were compared with the data obtained from oscillatory testing on a stress controlled rheometer. The methods were improved in several areas by testing different cup sizes, rotational speeds, and viscometers and correcting torque-time responses to obtain most accurate results possible. The developed method, along with the torque-time response obtained from the viscometer, was capable of measuring viscoelastic parameters for the tested materials and further development could design a new quality control device directed towards viscoelastic property measurement.

Cite this publication as follows:
Tanjore D, Daubert CR: A vane-in-cup approach to measure viscoelastic properties of gelatin gels through torque-time responses from Brookfield YR-I viscometer, Appl. Rheol. 21 (2011) 63172.

Cite this publication as follows:
Sanchez-Ferrer A: Magnetic resonance in food science (J.-P. Renou, P.S. Belton, G.A. Webb, Eds.), Appl. Rheol. 21 (2011) 324.

We herein describe a set of rheological measurements that were carried out in order to characterize the solidification of photopolymers. The solidification depends on the length of time of exposure to UV light, and the intensity of that light, which reduces with distance from the irradiative surface. Liquid prepolymer was solidified inside the gap of a parallel disk rheometer by irradiation of the prepolymer with UV light through a fixed quartz disk. The rheological time-dependent changes were measured and analyzed for both unidirectional and oscillatory shear. The results were compared with those obtained by direct measurement in the absence of shear. When the thickness of the sample was less than 0.1 mm, the analysis for unidirectional shear flow yielded a reasonable agreement for both critical exposure and solidified depth. When the thickness was greater than 0.1 mm, the application of unidirectional shear delayed the start of the solidification but then caused it to occur more rapidly. This dependence of the solidification on the thickness of the sample was more significant for dispersed systems of nanotubes and for dynamic measurements made under oscillatory shear. The increase in viscosity due to photopolymerization was also estimated, and its effect was discussed.

Cite this publication as follows:
Darsono N, Mizunuma H, Obara H: Rheological study of the solidification of photopolymer and dispersed nanotube systems, Appl. Rheol. 21 (2011) 63566.

A new conceptual non-contact method for liquid viscosity measurement in capillary tube using mobile phone as the data acquisition facility is proposed. The video and image for the capillary force driven flow of the test liquid was recorded by the phone camera. After the imaging reconstruction of the flow velocity in the horizontal capillary and the capillary head in the vertical direction, a digital image processing software was developed to calculate the liquid viscosity in MATLAB 2007b environment, recurring to the established theoretical correlation for flow mechanics. To demonstrate the feasibility and accuracy of the method, 10 groups of liquid were measured and the results were compared with the data obtained from a standard rotating viscometer. The relative error was found falling in the range of 0 ~ 20 %. This study establishes a pervasive low cost way for viscosity measurement of various solutions.

Cite this publication as follows:
Yang Y, Wang H, Liu J: Mobile Phone Enabled Pervasive Measurement of Liquid Viscosity, Appl. Rheol. 21 (2011) 63890.

Cite this publication as follows:
Oberdisse J, Genix A, Couty M, Schneider GJ, Pyckhout-Hintzen W: 3rd European Workshop on Nanocomposites and Polymer Dynamics (2011), Appl. Rheol. 21 (2011) 299.

An apparatus for small angle light scattering (SALS) and light transmission measurements under shear was built and tested at the University of Massachusetts Amherst. As a new development, the polarization direction can be rotated by a liquid crystal polarization rotator (LCPR) with a short response time of about 20 ms.The experiments were controlled and analyzed with a LabVIEWTM based code (LabVIEW-TM 7.1) in real time. Quiescent and flow-induced crystallization experiments on isotactic poly-1-butene (iPB) were conducted to demonstrate the instrument and software capabilities. Software was designed with a modular approach, so that further modules can be added to investigate other systems such as polymer blends, colloidal suspensions, solutions with droplets etc. A replica of the SALS apparatus was custom built for ExxonMobil Research in Clinton NJ.

Cite this publication as follows:
Arora D, Nandi S, Winter HH: A new generation of light scattering device with real time data analysis for rheo-optical measurements, Appl. Rheol. 21 (2011) 42633.

Black liquor is the maJor by-product and biomass fuel of pulp mills, and the understanding of its thermophysical properties is essential for the improvement of the design and the operation of chemical recovery processes. In this work, the rheological behaviour of industrial samples of Eucalyptus globulus black liquor was investigated to study the influence of solids content ranging from 13 % for the white liquor sample, and from 30 to 65 % of dissolved solids for the black liquors, and of temperature from 298.15 to 338.15 K, covering shear rates from 0 to 1200 s-1. The black liquor showed a complex non-Newtonian behaviour, presenting at low shear rates a pseudoplastic behaviour, followed by a viscosity Newtonian plateau. The modified Quemada model gives an expression applicable to all the shear rate range, which was used to describe the flow curves for the viscosity of E. globulus black liquors samples. Moreover, a correlation based on a VTF model with parameters dependent on solids content was successfully developed for the viscosity data of the Newtonian plateau.

Cite this publication as follows:
Costa H, Egas A, Ferreira A, Lobo L: Rheology of Eucalyptus Globulus Kraft Black Liquor, Appl. Rheol. 21 (2011) 42533.

We report unprecedented non-Einstein-like viscosity decrease of polymer melts by special low glass transition, Tg, inorganic tin fluorophosphate glass (Pglass) that is remarkably counter to widely accepted dispersions, suspensions, and composites theories. The well dispersed low-Tg Pglass dramatically decrease the polymer melt viscosity while increasing its Young's modulus in the solid state at low loading (<2%) however decreasing with high loading (>2%), making the hybrid Pglass/polymer solid material stronger yet easier to process in the liquid state. Disruption of the Nylon 6 melt dynamics, strong physicochemical interactions, and submicrometer nanophase separation (proved by rheometry, FTIR, DSC, SEM, NMR and XRD) are thought to be responsible for this experimental fact. This finding should beneficially impact our ability to prepare lower viscosity, very highly filled Nylon 6 melts from already existing materials and polymer processing methods such as inJection molding and extrusion, making the simple strategy potentially widely applicable in a number of applications such as thinner barrier resistant thin films, composites, and membranes for heterogeneous catalysis.

Cite this publication as follows:
Meng Y, Otaigbe J: Mechanism of unexpected viscosity decrease of polymer melts by low-Tg inorganic phosphate glass during processing, Appl. Rheol. 21 (2011) 42654.

Rheological behaviour of culture broth stands as a fundamental parameter in bioprocess performances because it affects simultaneously the heat and mass transfer as well as the flow pattern. On-line measurements of rheological behaviour are hardly compatible with the operating condition with respect to accurate and stringent conditions imposed by cell culture strategy. Our scientific and technical obJectives are (i) to develop and identify an experimental device enabling on-line rheometry and (ii) to discuss and compare on-line and off-line measurements. In this aim, a bioreactor was equipped with a derivation loop including a specific on-line rheometric device as well as additional physical and biological measurements (specific density, mass flow rate, electrical conductivity, pH,pO2 and temperature) during microbial cell cultures. In a first time, friction curves of calibrated ducts were established with Newtonian and non-Newtonian shear-thinning fluids. In a second time, axenic cultures with two microorganisms (bacteria and yeast exhibiting different sizes) were investigated in pure oxidative culture in order to produce biomass under high cell concentrations: ~ 40 to 110 gCDW/l for E. coli (bacteria) and ~ 75 to 105 gCDW/l for Y. lipolytica (yeast). Cell broths exhibited Newtonian behaviour for E. coli and shear-thinning behaviour for Y. lipolytica, which were both dependant on biomass concentration. On-line and off-line rheological measurements are consistent for E. coli and Y. lipolytica, but significantly differed. On-line estimated viscosity appears higher than off-line apparent viscosity. Several assumptions in relation with microorganism physiology and metabolism (size, morphology, surface properties, concentration, biological activity) could be formulated in agreement with scientific literature. On-line rheology brings new insight to investigate complex interaction between physical and biological phenomena.

Cite this publication as follows:
Manon Y, Anne-Archard D, Uribelarrea J, Molina-Jouve C, Fillaudeau L: Physical and biological study of cell cultures in a bioreactor: on-line and off-line rheological analyses, Appl. Rheol. 21 (2011) 35167.

The interaction between magnetic particles in a bed fluidized by a gas is determined by the magnetizing action of an externally applied magnetic field. As the strength of the field is increased there comes a point at which the bed transits from a fluidlike to a solidlike stable state. Interparticle attractive forces induced by the applied field causes chainlike agglomeration of the particles, which confers the stabilized structure with a mechanical strength. In this paper we report experimental results on the yield stress of fluidized beds of fine magnetic particles stabilized by an externally applied magnetic field. Our results show that, in analogy with magnetorheological fluids (MRFs), particle structuring determines essentially the yield stress of magnetofluidized beds (MFBs). Moreover, our work shows that the dependence of the yield stress on particle size, which stands as a controversial issue in the study of MRFs, can be understood from the analysis of the Jamming transition as affected by the size of the particles and the strength of the field.

Cite this publication as follows:
Valverde JM, Espin MJ, Quintanilla MAS, Castellanos A: Jamming and rheology of fluidized beds of magnetized particles, Appl. Rheol. 21 (2011) 35179.

Cite this publication as follows:
Fischer P: Rheology of Particulate Dispersions and Composites (Rajinder Pal), Appl. Rheol. 21 (2011) 75.

Cite this publication as follows:
deVicente J, Hidalgo-Alvarez R: Second International Soft Matter Conference 2010 - ISMC2010, Appl. Rheol. 21 (2011) 122.

The composition of high concentration ash slurry requires careful selection of particle size distribution (PSD) to achieve the required rheological properties for efficient disposal through pipelines. In the present study, the maximum static settled concentration, CW-max, tests and rheological measurements were carried out for a total eighteen nos. of ash samples (nine nos. of fly ash samples and nine nos. of fly ash.bottom ash mixture samples) in the concentration range of 60 - 70 wt%. It was observed that the CW-max value reached maximum for the composition of mixture slurry consisting of fly ash and bottom ash with d50 as 6.4 μm and 144 μm respectively at a fixed blend ratio (weight ratio of fly ash to bottom ash) of 4:1. This was attributed to the packing effect and was correlated to the ratio of surface to surface separation for the coarse bottom ash particles, β, to the average fly ash particle size, d50-f, to achieve higher solids concentration. The rheological behaviour of the ash slurry samples were described by non-Newtonian power law model in the range of solids concentration studied. Also a substantial reduction in viscosity was observed for the same composition of mixture slurry sample which was attributed to the poly-dispersive characteristics of the ash particles. It was indicated that the slurry viscosity was very much influenced by particle size ratio (λ = dlarge/dsmall) and volume fraction of solids. The study revels that the blending of fly ash and bottom ash at a controlled PSD may be employed for preparation of high concentration ash mixture slurry for pipeline transport.

Cite this publication as follows:
Senapati PK, Mishra BK, Sahu A, Kumar V: Effective composition of high concentration fly ash-bottom ash mixture slurry for efficient disposal through pipelines, Appl. Rheol. 21 (2011) 23480.

This paper evaluates the use of lightweight aggregates (LWA), namely perlite (PER) and vermiculite (VER) in cement mortars. The workability of mortars was defined in rheometer and flow table tests. Three distinct LWA levels were added (0 - 3, 4.5 - 7, and 9 - 10.5 wt%) requiring the use of distinct water/solids (W/S) ratios (0.18, 0.265 and 0.35, respectively). In order to evaluate the performance of such formulations in the hardened state, the flexural and compressive strength after 28 days curing was also measured. In general, LWA caused a high variation on the yield stress and spread on table, being the yield stress the best rheological parameter to be related with the flow table. PER exerts a strong impact on initial yield stress, while the effect of VER is stronger for longer rheology testing periods. The compressive strength ranged from 12.3 MPa (0 % LWA) to 2.77 MPa (PER) and 2.39 MPa (VER).

Cite this publication as follows:
Senff L, Hotza D, Labrincha JA: Effect of lightweight aggregates addition on the rheological properties and the hardened state of mortars, Appl. Rheol. 21 (2011) 13668.

Cite this publication as follows:
Kubyshkina G: The 7th International Conference on Mechanics of Time-Dependent Materials, Appl. Rheol. 21 (2011) 48.

This paper presents an experimental study of the rheological behaviour of water-in-oil mixtures without any additive, up to 10 % of mass water concentration, where the mixture is considered to be a Newtonian fluid. The selected oil is a classical turbine mineral oil. Viscosity was measured for five temperatures, ranging from 10 to 80 C, for droplet size below 30 $\mu$m. A light decrease of viscosity was detected for water concentrations below 0.1 %. For concentrations greater than 0.2 %, viscosity increases with water concentration. Moreover, the variation of viscosity with temperature shows good correlation with both Walther model and Mac Coull & Walther model. Finally, a new model of water-in-oil mixtures viscosity as a function of temperature and concentration was defined.

Cite this publication as follows:
Harika E, Jarny S, Monnet P, Bouyer J, Fillon M: Effect of water pollution on rheological properties of lubricating oil, Appl. Rheol. 21 (2011) 12613.

The effect of shear viscosity on taste and mouthfeel perception has been extensively studied; however, the effect of extensional viscosity on sensory perception has been mostly neglected. This may be important as in-mouth processing is complex and probably best described as a superposition of shear and extensional flow characteristics. Fluid mechanics researchers interested in separating elastic effects from viscous effects use Boger fluids and this approach was adopted here to investigate the effect of fluid elasticity on sensory perception. For the first time, two food grade Boger fluids based on glucose syrup and aqueous solutions of maltodextrin as solvents and xanthan gum as high molecular weight polymer were formulated. The elasticity of the Boger fluids was characterised in rotational shear rheometry, in a filament break-up device and in microcontraction flow. Saltiness perception and mouthfeel of the Boger fluids and samples corresponding to the respective solvent were analysed. Surprisingly, there were no significant differences. Hypotheses attributing this finding to the intrinsic properties of the samples are discussed. A maJor study would be required to gain in-depth understanding of the sensory properties of these fluids as their flow properties are very different from typical liquid foods.

Cite this publication as follows:
Koliandris A, Rondeau E, Hewson L, Hort J, Taylor AJ, Cooper-White JJ, Wolf B: Food grade Boger fluids for sensory studies, Appl. Rheol. 21 (2011) 13777.

The application of sustainability principles in construction encourages the development of new products,with new functionalities and applications, able to improve buildings environmental performance. The use of latent heat storage materials in lime mortars aims to reduce the energy consumption of buildings.This work intends to evaluate the impact of phase change materials (PCM) incorporation in rheological and hardened state properties of aerial lime mortars. A fresh state characterization was conducted through the rheological study complemented with flow table tests of different mortar formulations. To complete the mortar characterization some hardened state properties (porosity, mechanical strength and microstructure) after 28 days, were also evaluated. It was concluded that, the PCM microcapsules incorporation does not compromise aerial lime mortars overall performance and may help to improve some characteristics like workability and mechanical strength. Therefore, it is possible to reduce the energy demand in old buildings, improving their performance and sustainability.

Cite this publication as follows:
Lucas S, Senff L, Ferreira V, BarrosodeAguiar J, Labrincha J: Fresh state characterization of lime mortars for latent heat storage, Appl. Rheol. 20 (2010) 63162.

Bitumen is undoubtedly the most important material in the construction and rehabilitation of flexible road pavements. By increasing the temperature, bitumen changes from brittle solid, to viscoelastic solid and finally to Newtonian fluid. The rheological characteristics of bitumen also vary greatly due to aging,which is a phenomenon initiated in the phases of production and application of bituminous (asphalt) mixtures and continued during the life of road pavements. The aim of this work is to study several rheological parameters in order to evaluate if they are able to quantify the aging of various types of bitumens. Four bitumens from the same distillation column in the refinery, but with different penetration grades, were aged by using the RTFOT method, which simulates the aging of the bitumen during the asphalt mixture production and pavement construction. The original (base) and aged bitumens were characterized with conventional tests used in the paving industry, and the results were compared with the rheological characteristics obtained with small amplitude oscillatory shear tests. Aging was assessed at high temperatures (110 to 180oC) through the activation energy computed from the temperature dependence of the Newtonian viscosity. However, the comparison of the characteristic relaxation times extracted from master curves measured at medium/low temperatures (between 25 to 80oC), proved to be the most sensitive indicator of bitumen aging.

Cite this publication as follows:
Peralta J, Hilliou L, Silva H, Machado A, Pais J, Oliveira J: Rheological Quantification of Bitumen Aging: Definition of a New Sensitive Parameter, Appl. Rheol. 20 (2010) 63293.

An experimental set-up was used to visually observe the characteristics of bubbles as they moved up a column holding xanthan gum crystal suspensions. The bubble rise characteristics in xanthan gum solutions with crystal suspension are presented in this paper.The suspensions were made by using different concentrations of xanthan gum solutions with 0.23 mm mean diameter polystyrene crystal particles. The influence of the dimensionless quantities; namely the Reynolds number, Re, the Weber number, We, and the drag co-efficient, cd, are identified for the determination of the bubble rise velocity. The effect of these dimensionless groups together with the Eotvos number, Eo, the Froude number, Fr, and the bubble deformation parameter, D, on the bubble rise velocity and bubble traJectory are analysed. The experimental results show that the average bubble velocity increases with the increase in bubble volume for xanthan gum crystal suspensions. At high We, Eo and Re, bubbles are spherical-capped and their velocities are found to be very high. At low We and Eo, the surface tension force is significant compared to the inertia force. The viscous forces were shown to have no substantial effect on the bubble rise velocity for 45 < Re < 299. The results show that the drag co-efficient decreases with the increase in bubble velocity and Re. The traJectory analysis showed that small bubbles followed a zigzag motion while larger bubbles followed a spiral motion. The smaller bubbles experienced less horizontal motion in crystal suspended xanthan gum solutions while larger bubbles exhibited a greater degree of spiral motion than those seen in the previous studies on the bubble rise in xanthan gum solutions without crystal.

Cite this publication as follows:
Hassan N, Khan M, Rasul M, Rackemann D: Bubble Rise Velocity and Trajectory in Xanthan Gum Crystal Suspension, Appl. Rheol. 20 (2010) 65102.

The classification of a concrete mixture as self-compacting (SCC) is performed by a series of empirical characterization tests that have been designed to assess not only the flowability of the mixture but also its segregation resistance and filling ability. The obJective of the present work is to correlate the rheological parameters of SCC matrix, yield stress and plastic viscosity, to slump flow measurements. The focus of the slump flow test investigation was centered on the fully yielded flow regime and an empirical model relating the yield stress to material and flow parameters is proposed. Our experimental data revealed that the time for a spread of 500 mm which is used in engineering practice as reference for measurement parameters, is an arbitrary choice. Our findings indicate that the non-dimensional final spread is linearly related to the non-dimensional yield-stress. Finally,there are strong indications that the non-dimensional viscosity of the mixture is associated with the non-dimensional final spread as well as the stopping time of the slump flow; this experimental data set suggests an exponential decay of the final spread and stopping time with viscosity.

Cite this publication as follows:
Neophytou M, Pourgouri S, Kanellopoulos A, Petrou M, Ioannou I, Georgiou GC, Alexandrou A: Determination of the rheological parameters of self-compacting concrete matrix using slump flow test, Appl. Rheol. 20 (2010) 62402.

This paper is concerned with the determination of the constitutive parameters of low concentrations of the complex fluid polyethylene glycol (PEO). Velocity fields of PEO solutions in a microfluidic T-Junction have been measured for pressure driven flow using micron resolution particle image velocimetry. As the fluid is forced to turn the corner of the T-Junction a range of shear rates, and therefore viscosities, is produced.Thus it is possible to establish the rheological profile from a single experiment. An inverse method used in conJunction with a finite element model was used to determine the constitutive parameters of the fluid, estimated to within 1.5 % error in all three cases considered.

Cite this publication as follows:
Bandulasena HC, Zimmerman WB, Rees JM: Rheometry of non-Newtonian polymer solution using microchannel pressure driven flow, Appl. Rheol. 20 (2010) 55608.

Electrorheological (ER) and dielectric properties of silicone-oil suspensions of polyaniline (PANI) particles protonated with phosphoric and tetrafluoroboric acids to various doping level have been investigated. The particle conductivity was thus varied between the order of 10-9 S/cm and 10-4 S/cm. The dynamic yield stresses obtained at controlled shear rate mode viscometry, the storage moduli from the oscillatory shear experiments and the dielectric relaxation times from frequency dependences of dielectric constant and loss factor were used as criteria of rigidity or elasticity of ER structures and particle mobility in the electric field. The conductivity of suspension particles plays a decisive role in their ER behaviour. The ER efficiency increased as conductivity of dispersed particles raised, irrespective of the type of employed acid used for the protonation of PANI.

Cite this publication as follows:
Stenicka M, Pavlinek V, Saha P, Blinova NV, Stejskal J, Quadrat O: Electrorheology of suspensions of variously protonated polyaniline particles under steady and oscillatory shear, Appl. Rheol. 20 (2010) 55371.

Thixotropy is an important rheological behavior of waxy crude oils. The obJective of this paper is to demonstrate existing model's abilities to describe shear stress decay behaviors of waxy crude oils at constant shear rates. Seven models specially developed for or currently used to waxy crude oils are reviewed as well as two viscoelastic-thixotropic models for human blood. Stress decay behaviors were measured for four waxy crude oils and at various temperatures. Each of the models was used to fit the stress decay plots at a single shear rate, and at multiple shear rates, respectively. Globally, Zhao's model, a complex viscoplatic model with two structure parameters and twelve physical & fitting parameters,matched the experimental plots better than other compared models. While the three models with viscoelastic backgrounds were not quite successful. For use of models, one may make choice by comprehensively considering a model's complexity in mathematic form and abilities to describe the rheological behaviors.

Cite this publication as follows:
Zhang J, Guo L, Teng H: Evaluation of thixotropic models for waxy crude oils based on shear stress decay at constant shear rates, Appl. Rheol. 20 (2010) 53944.

Cite this publication as follows:
Maldonado-Valderrama J, Martin-Rodriguez A, Galvez-Ruiz MJ, Cabrerizo-Vilchez MA: Food Colloids 2010: On the Road from Interfaces to Consumers, Appl. Rheol. 20 (2010) 243.

We present a model for osmotic pressure and shear modulus of highly concentrated emulsions by including the interdroplet interaction in terms of disJoining pressure. The results show that even a small addition in interdroplet interaction can lead to significant deviations from the classical Princen-Lacasse-Mason models that take into account only the surface energy as the sole source of elasticity. The newly proposed model predicts new effects, in particular the possibility of nonlinear dependency of elastic modulus on the droplet size, and can be used to discuss the elasticity sources of highly concentrated emulsions. In the second part of this article, the unusual elasticity of highly concentrated explosive emulsions is discussed by using the proposed model.

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Foudazi R, Masalova I, Malkin A: Effect of interdroplet interaction on elasticity of highly concentrated emulsions, Appl. Rheol. 20 (2010) 45096.

The yield stress of a magnetorheological fluid was measured as a function of magnetic flux density using different techniques. The yield stress values were determined by extrapolating the experimental shear stress-shear rate data to zero shear rate with the help of Bingham and Herschel-Bulkley models, and by using stress ramp and dynamic oscillatory tests.To obtain the rheological data, the rotational rheometer equipped with a magnetic field generator and a plate-and-plate measuring geometry was used. The different methods produced yield stress values which were in reasonable agreement with each other.

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Jonkkari I, Syrjala S: Evaluation of techniques for measuring the yield stress of a magnetorheological fluid, Appl. Rheol. 20 (2010) 45875.

This article reports viscosity data on a series of colloidal dispersions collected as part of the International Nanofluid Property Benchmark Exercise (INPBE). Data are reported for seven different fluids that include dispersions of metal-oxide nanoparticles in water, and in synthetic oil. These fluids, which are also referred to as 'nanofluids,' are currently being researched for their potential to function as heat transfer fluids. In a recently published paper from the INPBE study, thermal conductivity data from more than 30 laboratories around the world were reported and analyzed. Here, we examine the influence of particle shape and concentration on the viscosity of these same nanofluids and compare data to predictions from classical theories on suspension rheology.

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Venerus DC, Buongiorno J, Christianson R, Townsend J, Bang I, Chen G, Chung S, Chyu M, Chen H, Ding Y, Dubois F, Dzido G, Funfschilling D, Galand Q, Gao J, Hong H, Horton M, Hu L-W, Iorio CS, Jarzebski AB, Jiang Y, Kabelac S, Kedzierski MA, Kim C, Kim J-H, Kim S, McKrell T, Ni R, Philip J, Prabhat N, Song P, VanVaerenbergh S, Wen D, Witharana S, Zhao X-Z, Zhou S-Q: Viscosity measurements on colloidal dispersions (nanofluids) for heat transfer applications, Appl. Rheol. 20 (2010) 44582.

A rheological characterization and extrusion of aqueous suspensions of natural zeolites were carried out in this work. Preparation of suspensions followed similar routes to those used for the colloidal processing of ceramic powders.The suspensions were prepared at different volume fractions (v/v%) ranging from 5 to 61 v/v% for a pH value of 7. The suspensions showed a Newtonian behavior for solid contents up to 20 v/v% and shear thinning at higher solid loads. For solid contents above 35 v/v%, the suspensions exhibited hysteresis and a yield stress that growth exponentially with the solid load. The appearance of a yield stress and its fast growing at relatively low solid concentration, as compared to other type of ceramic suspensions, is attributed to several factors as inter-particle interactions, the presence of relatively large particles and to the influence of their irregular morphology. Also, a breaking stress was measured for solid contents above 35 v/v%, which characterizes a failure of the structure of the suspensions after yielding. This breaking stress determines the onset of slip flow of the suspensions, which is interpreted in this work as a signal of good extrusion characteristics. Finally, inexpensive and free of surface defects tubes were obtained from natural zeolites.

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Zacahua-Tlacuatl G, Perez-Gonzalez J, Castro-Arellano JJ, Balmorii Ramirez: Rheological characterization and extrusion of suspensions of natural zeolites, Appl. Rheol. 20 (2010) 34037.

We propose an exhaustive experimental characterization of a series of poly(n-butyl acrylate) samples that were synthesized by controlled radical polymerization and have different molecular weights. We focus on the rheological behavior of these polymers and propose a model of their rheological behavior using a molecular model based on the reptation concept.We report the principal rheological parameters for these homopolymers and demonstrate good agreement between model predictions and experimental data.

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Jullian N, Leonardi F, Grassl B, Peyrelasse J, Derail C: Rheological characterization and molecular modeling of poly(n-butyl acrylate), Appl. Rheol. 20 (2010) 33685.

Two types of starch gels made with various starch/water concentrations were studied in terms of their mechanical behaviour. Indentation tests were performed which revealed a rate independent load-deflection response. An inverse analysis based on the Marquardt-Levenberg optimisation algorithm and Finite Element Analysis was used to derive the stress-strain behaviour from the indentation data. The inverse predictions for the stress-strain curves are in good agreement with the direct measurements from uniaxial compression and shear tests up to high values of strain. The validity of the method was proven for both self-supporting and non self-supporting gels, with initial moduli ranging from a very small 60 Pa to 55 kPa. Thus the indentation characterisation method is proven as a powerful, fast and efficient way of evaluating and/or monitoring the behaviour of gels.

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Gamonpilas C, Charalambides M, Williams J, Dooling P, Gibbon S: On the characterization of the mechanical behaviour of starch gels using indentation techniques, Appl. Rheol. 20 (2010) 33283.

Fumed silica suspensions in low molecular weight liquids are used in many photonic and microelectronic applications, playing its rheology a maJor role in the effectiveness of their usage. Particle-particle and particle-liquid medium interactions of suspensions of hydrophilic fumed silica in low molecular weight polar media, polypropylene glycol of 400 and 750 g/mol, concretely, have been already investigated.There, the affinity between polar solvent molecules and fumed silica particles prevents the formation of a 3D gel network. In this work it has been found that fumed silica can develop a flocculated suspension when it is dispersed in polypropylene glycol with a molecular weight of 2000 g/mol. Besides, it has been found that this suspension exhibits time dependent behaviour within its reversible shear thinning region, which is related to thixoelasticity. The experimental method, proposed theoretically by Cheng in 1986 to obtain the dynamic yield stress in thixotropic systems has been here extended successfully to a thixoelastic system.

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Galindo-Rosales FJ, Rubio-Hernandez FJ: Static and Dynamic Yield Stresses of Aerosil(R) 200 suspension in Polypropylene Glycol, Appl. Rheol. 20 (2010) 22787.

Surface rheological properties affect the dynamics of vesicles, nanoparticles, emulsion droplets, foam bubbles, polymer microcapsules, liquid Jets, living cells, lung avioli, thin liquid films, and many other multiphase systems. Surface rheology is therefore relevant for a wide range of disciplines in the areas of physics, chemistry, engineering, biology, and medicine. Currently used descriptions of surface rheology have a number of limitations, and in particular are hard to generalize to the large deformation regime. Data are often analyzed with constitutive equations based on straightforward generalizations of models developed for describing bulk phase rheology. Since the latter are in general designed to describe incompressible materials, they are not guaranteed to describe highly compressible interfaces correctly. Here we discuss a unified approach to surface rheology based on nonequilibrium thermodynamics (NET) that provides a consistent set of balance and constitutive equations for the unambiguous determination of surface rheological parameters, both near and far beyond equilibrium. A closer integration of experimental surface rheology and multiphase nonequilibrium thermodynamics would clearly be beneficial for both disciplines.

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Sagis L: Rheology of complex fluid-fluid interfaces: a unified approach based on nonequilibrium thermodynamics, Appl. Rheol. 20 (2010) 24380.

A review of rheological in situ measurement techniques applied to liquids and soft solids at high pressures of more than 100 MPa is presented.The instruments reported in the literature fall into four groups: concentric cylinder rheometers, falling body and rolling ball viscometers, capillary viscometers and oscillatory systems. The measurement techniques are classified with respect to the possibility of carrying out an absolute measurement. Some typical experimental problems and error sources connected with high-pressure conditions are outlined and briefly discussed. The maJority of the measurement techniques described in the literature are designed for the determination of the dynamic shear viscosity or viscosity function and only a few contributions report on the development of devices for the determination of other rheological parameters, e.g. normal stress differences or viscoelastic moduli.

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Kulisiewicz L, Delgado A: High-pressure rheological measurement methods: A review, Appl. Rheol. 20 (2010) 13018.

The present work deals with the study of the rheological behaviour of PVC (polyvinylchloride) pastes containing particles of ~ 150 μm in diameter obtained by polymerization in suspension.The rheological properties of the PVC pastes were characterized by creep experiments using 6-bladed vane geometry. The pastes show a very small compliance and a very narrow linear domain. The effects of temperature, of interstitial liquid and of saturation level of the wet paste were studied in detail and it was found that they significantly modify the creep behaviour. Other techniques allowed us to characterise rearrangements of the particles under load, in compression, by their oedometric modulus and by the failure stresses measured using a shear box. A very high oedometric modulus was measured (20 MPa) and by application of the Mohr-Coulomb criterion the internal friction coefficient (μ ~ 0.6) and the cohesion of the materials were deduced.We conclude from this investigation that the interfacial properties of the grains play a maJor role in the behaviour of the wet pastes under shear or in compression. The paper illustrates the difficulties in measuring the rheological and the structural properties of Jammed systems made from non-ideal (real) particles and reveals the key parameters in studying such media.

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Rabia A, Djabourov M, Feuillebois F, Lasuye T: Rheology of wet pastes of PVC particles, Appl. Rheol. 20 (2010) 11961.

The rheological behavior of ceramic oxide hydroxide alumina pastes with high solid loading is investigated. In order to enable an adequate and experimentally rheological characterization, the measurements are carried out with a Rheostress viscometer under isothermal conditions. Various compositions of a commercial AlOOH powder and binder mixture are investigated. We discuss the variation of loss modulus G', storage modulus G'', apparent and complex viscosities h, h* as function of frequency and shear rate.The solid phase used here is the boehmite; the most important precursor for the g-Al2O3 phase for several applications such as catalysts or functional layers of ceramics. Solid phase compositions used are Justified by the applications of boehmite in the manufacturing of catalytic materials. A transition zone that appears at a concentration of 55 %wt of the solid phase (Pural) and at which the rheological behavior changes from viscoelastic to elastic is observed. This transition is of a importance as far as ceramic manufacturing is concerned.

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Belkham NeH, Mehamha A, Benachour D: Rheological behavior of alumina ceramic pastes, Appl. Rheol. 19 (2009) 64969.

The rheological behavior of emulsions has been extensively investigated through experiments made at atmospheric pressure. This study presents a new experimental characterization of these fluids with measurements performed under pressure and in a large range of temperature.The results show that viscosities obey Barus model that predicts an exponential increase with pressure. The extent of the increase is governed by a unique piezoviscous coefficient. This coefficient exhibits a non monotonous variation with temperature. It has been shown that its thermal dependence and its value can be related to the viscoelastic properties of the fluid. The coefficient is an increasing function of temperature for a solid-like behaviour and a decreasing function of temperature for a liquid-like behaviour.This approach has been applied to heavy crude oils. It has been demonstrated that water droplets and oil composition modify the elastic character of heavy crude oils and as a consequence they modify their piezoviscosity.

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Chaudemanche C, Henaut I, Argillier J: Combined effect of pressure and temperature on rheological properties of water-in-crude oil emulsions, Appl. Rheol. 19 (2009) 62210.

Adhesive properties of fresh mortar Joints containing different dosage rates of a water-soluble polymer (cellulose ether based) are investigated using the probe tack test. This test consists of measuring the evolution of the normal force required to separate at a given velocity two plates between which a thin layer of the sample is sandwiched. Three different adhesive components are inferred from the measured stretching force: cohesion, adhesion and adherence. The influence of the polymer dosage rate and the pulling velocity on the evolution of these adhesive properties is investigated. The adhesive components are then related the rheological properties of the mortars which are shown to behave as Herschel-Bulkley shear-thinning fluids.

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Kaci A, Bouras R, Chaouche M, Andreani P, Brossas H: Adhesive and Rheological Properties of Mortar Joints, Appl. Rheol. 19 (2009) 51970.

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Rheological Societies: Society's Site Sep 2009 - Feb 2010, Appl. Rheol. 19 (2009) 257.

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Coussot P, Kissi NE, Tassin J-F: De Gennes Discussion Conference 2009, a brief survey, Appl. Rheol. 19 (2009) 250.

Aggregation, heterogeneous flows, and complex particle geometries all pose challenges in rheology. This paper uses squeeze flow rheometry techniques to examine a case, where all of these played a role. The applicability of some squeeze theories is tested, and the ability to predict results based on suspension theories is examined. The squeeze flow data is shown to deviate from Stefan's Law [Stefan J, Sitz. Kais. Akad. Wiss. Math. Nat. Wien 69 (1874) 713-735]. The suspension rheology deviated from predicted theory, but by taking into account particle effects such as aggregation the fit to the empirical Maron-Pierce equation [Maron SH and PE Pierce, J. Coll. Sci. 11 (1956) 80-95] could be understood. The conclusions of this study show how using only squeeze flow techniques the synergistic nature of these effects can be better understood.

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McIntyre EC, Filisko FE: Squeeze Flow Rheology of Zeolite Suspensions, Appl. Rheol. 19 (2009) 44322.

The flow of non-Newtonian technical fibre suspensions (paper pulps) through a number of contractions is analysed and compared. Traditionally technical fibre flows are modelled as flow of fibres in a suspending medium. Here they are treated as crowded flows of fibre flocs from which the liquid may be squeezed in and out from. Compressive flows are common in the fibre-based process industry. They can e.g. be found in the headbox of a paper machine, in extruder nozzles in polymer technology, in the stirrer zone of mixers, etc. Traditionally such flows are analysed in elongational flow terms. Here it will be demonstrated that elongational and compressive flows for technical fibres suspensions differ qualitatively. The nature of technical fibre flocs is also discussed. For historic reasons they have come to be regarded as the outcome of a flocculation process of electrostatic-colloidal and/or mechanical-entanglement type. It will be shown that such a process is unnecessary for technical fibre suspensions and that these flocs are qualitatively different, viz. frozen-developed dissipative structures of the flocky fibre flow from which they originate. It will also be demonstrated that technical fibre flocs, in contrast with flocs of the chemically flocked type, are basically non-coherent, i.e. not kept together by themselves. It is this non-coherence that makes a compressive approach fruitful, for these economically important flows. An attempt to explain the reasons behind the present state of fibre flow theory is presented. The ambition is to stop to the present inproductive tradition in technical fibre flow.

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Bjorkman U: The non-Newtonian Fluid Mechanics of Technical Fibre Suspensions: Compressive Flows, Appl. Rheol. 19 (2009) 44290.

Filament breakup of high viscosity fluids with apparent yield stress has been investigated and strategies for an appropriate characterization of their behavior in CaBER experiments are discussed. Filament profiles of such fluids exhibit significant concave curvature. Accurate determination of filament shape is mandatory for understanding deformation behavior. Therefore, we have set up an optical train including high-speed camera, telecentric obJective and telecentric back-light illumination with a blue light emitting diode (LED) providing high contrast filament shape imaging. Image analysis allows for diameter determination with an accuracy of 3.55 μm/pixel. In addition to the transient filament diameter at the neck we have extracted the curvature at this point as a function of time and the region of deformation, in order to characterize the extensional flow behavior.We have investigated the time evolution of filament shape as a function of various experimental parameters like stretching time, velocity profile during stretching, stretching ratio and initial sample volume at constant stretching ratio. Filament thinning is independent of stretching time, tsub>s and stretching velocity profile. But when the same stretching ratio is applied at different initial volume fraction, filament curvature increases strongly with decreasing sample volume leading to an increase of filament life time according to the negative contribution of its curvature to the Laplace pressure inside the fluid.

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Niedzwiedz K, Arnolds O, Willenbacher N, Brummer R: Capillary Breakup Extensional Rheometry of Yield Stress Fluids, Appl. Rheol. 19 (2009) 41969.

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Dhont JKG, Gompper G, Richter D: Julich Soft Matter Days 2008, Appl. Rheol. 19 (2009) 176.

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Yeo L, Chang H, Wen W: Advances in Microfluidics and Nanofluidics (Hong Kong, 2009), Appl. Rheol. 19 (2009) 175.

The basic rheological properties of two Persian wheat flours - TaJan (11 % protein) and Back Cross Roshan (8 % protein) and two Australian wheat flours-JANZ (12.9 % protein) and Rosella (8.6 % protein) have been characterized.These properties have been interpreted via a damage function model. All samples could be reasonably well described by the damage function model with a power-law relaxation spectrum. Although the shear stresses in the Australian samples were higher, the relaxation parameter G(1) and power-law exponent p for the Australian varieties were lower than those for the Persian samples and the damage functions were different. Since protein contents were different, this indicates that the amount of protein is not the sole determinant of softness in the samples. The damage function f was also calculated for all samples. This function gives a measure of the softening due to working or kneading of the samples at a given strain level.

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Amirkaveei S: A Comparison of the Rheology of four Wheat Flour Doughs via a Damage Function Model, Appl. Rheol. 19 (2009) 34305.

The obJective of this work is to study quantitatively the errors introduced by the standard Newtonian and power-law assumptions used in the determination of the material properties of viscoplastic fluids from circular Couette experiments. The steady-state circular Couette flow of a Herschel-Bulkley fluid is solved assuming that the inner cylinder is rotating at constant speed while the outer one is fixed. Analytical solutions are presented for certain values of the power-law exponent. It is shown that the error in the computed wall shear rate, which is insignificant when the diameter ratio is closed to unity,may grow large depending on the diameter ratio and the material parameters.

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Chatzimina M, Georgiou G, Alexandrou A: Wall shear rates in circular Couette flow of a Herschel-Bulkley fluid, Appl. Rheol. 19 (2009) 34288.

Rheological creep and recovery tests have been applied at different assay times to xanthan gum hydrogels at several concentrations. The Burger model has been successfully applied to fit the creep data and to analyze results. Increasing the xanthan gum concentration also increases the elastic and viscous components without changing the molecular distribution of these hydrogels. A semi-empirical equation considering the different elements of the Burger model has been proposed to analyze compliance behavior in recovery tests. The dependence of the relative contribution to deformation of the Maxwell and Kelvin-Voigt units upon xanthan gum concentration and recovery assay times has been evaluated. Since the recovery ratio is the same for all hydrogels, we suggest parallel structures with no mutual interactions are formed when increasing concentration.

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Dolz M, Corrias F, Diez-Sales O, Casanovas A, Hernandez M: Influence of test times on creep and recovery behaviour of Xanthan gum hydrogels, Appl. Rheol. 19 (2009) 34201.

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Wiklund J: The Nordic Rheology Society Conference 2008, Appl. Rheol. 19 (2009) 121.

The authors previously introduced an activation model for the onset of shear thickening in electrically stabilized colloidal suspensions. It predicts that shear thickening occurs, when particles arranged along the compression axis in a sheared suspension do overcome the electrostatic repulsion at a critical shear stress, and are captured in the primary minimum of the DLVO interaction potential. A comparison with an experimental investigation on non-aqueous silica suspensions, carried out by Maranzano and Wagner, is performed. For particle systems that fall into the applicability range of the theory, a good coincidence between the experimental data and the model predictions can be found.

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Kaldasch J, Senge B, Laven J: Shear thickening in electrically stabilized non-aqueous colloidal suspensions, Appl. Rheol. 19 (2009) 23493.

Nanoclay dispersions in organic solvents are widely used in cosmetics for a variety of gels and creams, whose properties depend on the powder content and the processing method. The control of the shear applied during processing is therefore essential for achieving the required properties.This study demonstrates the utility of applying rheological measurements for characterizing cosmetic products based on nanoclays and relating their viscoelastic properties to end-use performances. In particular, a rheological characterization of bentonite dispersions in isododecane at different clay content and shear history is presented. For each inorganic content, both mixed samples and samples subJected to several calendering runs were studied. The effect of shear and clay content on the viscoelastic properties was investigated by a combination of oscillatory shear experiments under small-deformation conditions and by X-Ray diffraction. The tested samples showed a gel-like behaviour with a final structure depending on the applied shear stress. By increasing the inorganic content in the dispersion, a reduction in the gel stability to a further shear application was observed. Two models, developed for colloidal gels,were used to fit the rheological results enabling to evaluate the microstructure and the degree of dispersion of the tested samples and to relate the colloidal structure to the elastic properties.

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Lionetto F, Maffezzoli A: Rheological characterization of concentrarted nanoclay dispersions in an organic solvent, Appl. Rheol. 19 (2009) 23423.

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Bares V, Chara Z, Takeda Y: 6th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering (6 ISUD), Appl. Rheol. 19 (2009) 46.

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Yeo LY, Prakash-Jagadeeshan R, Friend JR: Complex Fluids and Microfluidics Workshop 2008 (CFMW08), Appl. Rheol. 19 (2009) 44.

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Mewis J: Short course on Suspension Rheology JCR, Appl. Rheol. 19 (2009) 43.

It is observed that, although consisting on very different formulations, the rheological properties of filled polyurethane adhesives may be rescaled onto simple master curves, and described with a small number of parameters: a yield stress, a low frequency elastic modulus and a characteristic time of flow. As a consequence, very simple and qualitative measurements of their deformations, such as the Dog Tail Test, may be used to deduce these parameters. By comparing the values obtained from Dog Tail Test measurements to well-controlled rheological measurements and to finite element computation, we show that such a simple and qualitative test may be used as a tool to measure both the yield stress and the elastic modulus of highly viscoelastic systems

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Lootens D, Jousset P, Dagallier C, Hebraud P, Flatt R: The ''Dog Tail Test'': a quick and dirty measure of yield stress. Application to polyurethane adhesives, Appl. Rheol. 19 (2009) 13726.

A systematic approach for collecting data from a torque rheometer is described, and the Bousmina et al. model is evaluated for HDPE, LDPE, LLDPE and HDPE/filler composites. The torque rheometer results are in good agreement to capillary and parallel plate viscometer measurements for neat polymers, when the torque values measured are corrected for the temperature rise due to viscous dissipation. For the composites, the torque and capillary results virtually coincide, but the viscosities are lower than those measured with the parallel plate instrument, in oscillatory mode, because the Cox-Merz rule is not valid. Although there are some limitations at high shear rates, due to viscous dissipation, the present work provides a proof and a methodology for the practical utility of torque rheometers for viscosity measurement in highly viscous systems.

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Santi CR, HageJr E, Correa CA, Vlachopoulos J: Torque Viscometry of Molten Polymers and Composites, Appl. Rheol. 19 (2009) 13148.

In the present study,we investigate the behaviour of the human blood in a stenosed blood vessel. The human blood is studied as a Newtonian as well as non-Newtonian fluid. We consider three rheological models of the shear-thinning non- Newtonian models and compare them with the Newtonian model. The blood flow through a stenosed blood vessel is studied numerically by solving the three dimensional Navier-Stokes equation along with the continuity equation and particular rheological model. Distribution of velocity, pressure,wall shear stresses and flow recirculation characteristics are determined for two time steps of the cardiac cycle. Present results indicate a significant influence of the shear-thinning viscous behaviour of a human blood on the most important hemodynamic parameters that play a key role in formation of atherosclerotic plaques. Last but not least, a systematic grid refinement analysis as well as numerical accuracy study IS performed and present numerical results may be treated as the benchmark.

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Ternik P, Marn J: Numerical study of blood flow in stenotic artery, Appl. Rheol. 19 (2009) 13060.

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Wilson HJ, Lettinga MP: Euromech Colloquium no. 492: Shear-banding Phenomena in Entangled Systems, Appl. Rheol. 18 (2008) 378.

This is a study of three-phase foam rheology to qualify penetration in to backing webs during frothed carpet compounds applications.Transient viscosity as a function of shear rate under a short time period is proposed to characterize flow of these compounds in response to a rapidly changing shear field during their application.We developed a fluid dynamic model that predicts the shear and pressure distributions in the compound during its processing in a metering nip based on process parameters and rheological results.We tested frothed compound formulations that are empirically known to be "penetrating" and "non-penetrating" based on the choice of soap (frothing surfactant). Formulated at the same froth density, penetrating to carpet backing compounds had large froth bubbles, relatively low transient shear viscosity and showed increasing foam breakdown due to shear when compared to non-penetrating compounds. Such frothed compounds readily collapse under shear and have relatively low dynamic stability, so the transition from a three-phased (air/aqueous/solid) to a twophased (water/solid) system occurs much easier and faster during application. The model predicts the shear rate development and a small difference in the pressure distributions in the applicator nip between these formulations, but reduction in drainage for the non-penetrating formulation.

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Triantafillopoulos N, Schreiner B, Vaughn J: Latex Carpet Compound Rheology, Appl. Rheol. 18 (2008) 64250.

Two approaches for determining the entrance pressure drop in capillary rheometry were compared with low-density polyethylene and polystyrene melts as test fluids. Direct measurements with the orifice die were found to yield higher values for the entrance pressure drop, and hence lower values for the wall shear stress, than the Bagley correction method. This was postulated to be caused by the sticking of the melt to the wall of the outlet region of the orifice die. The additional pressure drop created in the outlet region of the orifice die, when the flowing material fills it completely, was also evaluated by means of numerical flow simulation.

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Aho J, Syrjala S: Evaluation of different methods for determining the entrance pressure drop in capillary rheometry, Appl. Rheol. 18 (2008) 63258.

The rheological behaviour of non-Newtonian, highly concentrated and non-transparent fluids used in industry have so far been analysed using commercially available instruments, such as conventional rotational rheometers and tube viscometers. When dealing with the prediction of non-Newtonian flows in pipes, pipe fittings and open channels, most of the models used are empirical in nature. The fact that the fluids or slurries that are used normally are opaque, effectively narrows down the variety of applicable in-line rheometers even further, as these instruments are normally based on laser or visible light techniques, such as Laser Doppler Anemometry. In this research, an Ultrasonic Velocity Profiling technique (UVP), in combination with a pressure difference (PD) measurement, was tested to provide in-line measurement of rheological parameters. The main obJective of this research was to evaluate the capabilities of the UVP-PD technique for rheological characterisation of different concentrations of non-transparent non-Newtonian slurries. Kaolin, bentonite, Carboxymethyl Cellulose (CMC) and water solutions were used as model non-Newtonian mining slurries. Results determined by the UVP-PD method were compared with results obtained by off-line rheometry and in-line tube viscometry. The agreement between the UVP-PD method, tube viscometry and conventional rheometry was found to be within 15 % for all of the highly concentrated mineral suspensions investigated over a given range of shear rates.This method, if used in combination with a pressure difference technique (PD), has been found to have a significant potential in the development process of new in-line rheometers for process control within the mining industry.

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Kotze R, Haldenwang R, Slatter P: Rheological characterisation of highly concentrated mineral suspensions using an Ultrasonic Velocity Profiling with combined Pressure Difference method, Appl. Rheol. 18 (2008) 62114.

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Mitchell G, Davis F, Vaughan A, Mossman S: 75 Years of Polyethylene: Past Successes and Future Challenges, Appl. Rheol. 18 (2008) 316.

Complex fluids exhibit time-dependent changes in viscosity that have been ascribed to both thixotropy and aging. However, there is no consensus for which phenomenon is the origin of which changes. A novel thixotropic model is defined that incorporates aging. Conditions under which viscosity changes are due to thixotropy and aging are unambiguously defined. Viscosity changes in a complex fluid during a period of rest after destructuring exhibit a bifurcation at a critical volume fraction φC2. For volume fractions less than φC2 the viscosity remains finite in the limit t to infnity. For volume fractions above critical the viscosity grows without limit, so aging occurs at rest. At constant shear rate there is no bifurcation, whereas under constant shear stress the model predicts a new bifurcation in the viscosity at a critical stress σB, identical to the yield stress σy observed under steady conditions. The divergence of the viscosity for σ ≤ σB is best defined as aging. However, for σ > σB, where the viscosity remains finite, it seems preferable to use the concepts of restructuring and destructuring, rather than aging and reJuvenation. Nevertheless, when a stress σA (≤ σB) is applied during aging, slower aging is predicted and discussed as true reJuvenation. Plastic behaviour is predicted under steady conditions when σ > σB. The Herschel-Bulkley model fits the flow curve for stresses close to σB, whereas the Bingham model gives a better fit for σ >> σB. Finally, the model's predictions are shown to be consistent with experimental data from the literature for the transient behaviour of laponite gels.

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Quemada D: Aging, rejuvenation, and thixotropy in complex fluids: Time-dependence of the viscosity at rest and under constant shear rate or shear stress, Appl. Rheol. 18 (2008) 53298.

Investigations on the behaviour of superparamagnetic nanoparticles under the influence of a high gradient magnetic field in the vascular system is required for a better under-standing of magnetic drug targeting. The influence on the particle transport of the non-Newtonian and Newtonian properties of blood as well as the influence of the heart rate was therefore studied. An analytical model was developed and the calculation of particle traJectories is presented and evaluated.The results show that the non-Newtonian properties of the blood have a positive influence on the number of retended nanoparticles. The calculations also showed that the number of retained nanoparticles was lower in oscillatory flow profile than in steady flow. The influence of the heart rate can be neglected for Womersley numbers smaller than 1.5.

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Gleich B, Weyh T, Wolf B: Magnetic Drug Targeting: an analytical model for the influence of blood properties on particle trajectories, Appl. Rheol. 18 (2008) 52023.

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Kovacs J: Eurofillers 2007, Appl. Rheol. 18 (2008) 250.

Technical fibre flows are normally flocky but have theoretically mainly been treated as individual fibre flows. The reason for this can only be understood through the subJect's historic development. In Part 1 of this investigation the origin of fibre flow research was traced to the beginning of the 19th century, and was followed through its formative years at the first half of the 20th century up to about WWII. This second and final part takes us up to about the 1960s when the present main theoretical research tradition had been firmly established. An example of an alternative approach is given. Finally, some suggestions for future work are advanced. In Appendix methods of characterising the inner geometry of technical fibre suspensions are discussed.

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Bjorkman U: The Nonlinear History of Fibre Flow Research: Part 2. Continuation, Reflections and Suggestion, Appl. Rheol. 18 (2008) 34694.

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Cox S, Neethling S, Wilson HJ: British Society of Rheology mid-winter meeting on The Rheology of Foams and Emulsions, Appl. Rheol. 18 (2008) 193.

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Embery J: UK Polymer Showcase 2007 - Innovative Materials, Appl. Rheol. 18 (2008) 125.

Technical fibre flows are normally flocky, but have theoretically mainly been treated as individual fibre flows. The reason for this can only be understood in the context of historic development. In Part 1 of this historic investigation the roots of fibre flow research are traced to the beginning of the 19th century.The subsequent development is followed through its formative period in the first half of the 20th century up to about WW2. Part 2 will continue up to about 1960s when the present main tradition had been well established. In Part 2, an example of an alternative approach will also be given, and some proposals for future development presented.

Cite this publication as follows:
Bjorkman U: The Nonlinear History of Fibre Flow Research: Part 1. Background and Beginning, Appl. Rheol. 18 (2008) 23974.

Rheological behavior of asphalt is strongly affected by loading conditions, temperature and environment. One of the main challenges in understanding the rheology of asphalt is to relate the chemical constituents and the micro-structure of asphalt on one hand to its rheological behavior on the other hand. In this work, nonlinear rheological behaviour of asphalt was investigated using a structural rheological model. A first order kinetic equation to describe structural changes in asphalt has been incorporated with the nonlinear rheological model of White- Metzner. The resulting set of governing equations was solved numerically to describe the rheology of asphalts. Different modes of rheological testing and asphalts with different compositions were considered. An analysis and comparison of model behaviour with experimental data from the literature is carried out in both stress growth at constant shear rate and oscillatory shear modes. A strategy is proposed for the estimation and tuning of the model parameters based on available experimental data and literature. Qualitatively, the model can capture the rheological behaviour of non-Newtonian fluids such as asphalt under different modes of rheological testing. Quantitative analysis from this work shows that the model describes the rheological behaviour of asphalt for the temperature range of 20 - 60oC. It is demonstrated that a single set of equations tuned with the steady shear experimental data can be used to predict the nonlinear rheological behaviour of asphalts. In addition, it is shown that the model parameters can be related to the chemical composition of asphalts.

Cite this publication as follows:
Vijay R, Deshpande AP, Varughese S: Nonlinear rheological modeling of asphalt using White-Metzner model with structural parameter variation based asphaltene structural build-up and breakage, Appl. Rheol. 18 (2008) 23214.

The new ARES-G2 is a rotational rheometer based on the unique concept of separation of motor and force/torque transducer. Designed from ground up, a key obJective of the development proJect was to provide increased flexibility designing rheological experiments and to allow new and application specific test procedures. In order to achieve these goals all maJor instrument components such as the actuator, transducer, stage, data acquisition, environmental systems, etc. are developed as independent intelligent sub-assemblies, controlled by a central processor. The rigid firmware based on fixed test modes is replaced with a versatile user interface allowing a free combination of instrument instructions, which are downloaded to the instrument prior testing. Fast digital signal processing replaces the analog electronics providing faster, more accurate motor and transducer control and allowing the implementation of full stress control in oscillation and transient test modes. Significantly improved data acquisition with 5 fast data channels in all test modes enables SAOS and enhanced LAOS testing with complete support of higher harmonic analysis.

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Franck A: A new generation of separate motor and transducer rheometers, Appl. Rheol. 18 (2008) 44.

We show that the rheological characteristics of a fresh cement paste can be determined from inclined plane tests.The apparent flow curve measured from inclined plane flows coincides with the apparent rheogram from classical rheometer tests and the flow curve obtained from local Couette flow measurements with magnetic resonance imaging (MRI). In order to describe the thixotropic properties of these fluids we suggest to use a simple model, the four parameters of which may be determined from specific, practical, inclined plane experiments.

Cite this publication as follows:
Jarny S, Roussel N, LeRoy R, Coussot P: Thixotropic behavior of fresh cement pastes from inclined plane flow measurements, Appl. Rheol. 18 (2008) 14251.

a new technique of reconstruction of the velocity profile, the behaviour can be modelled by a unique equation including liquid and solid components but also a structural parameter. It is also rigorously demonstrated that the only one rheological behaviour in steady state in the liquid regime is a truncated power-law which can be defined only for a shear rate and a shear stress higher than a critical value. Moreover, the critical shear rate and shear stress increase with the solid content and depend on the fractal dimension of flocs which implies that thixotropic effects are all the more important as the sludge is thick and fresh.

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Baudez J-C: Physical aging and thixotropy in sludge rheology, Appl. Rheol. 18 (2008) 13495.

The rheologies of a shear-frozen commercial ice cream and of a model ice cream foam have been studied at - 5oC and other temperatures by capillary rheometry on a commercial manufacturing line and in a Multi-Pass Rheometer, respectively. Both were 50 vol% aerated emulsions of milk fat in an aqueous sucrose solution, but the model ice cream foam was without ice crystals. The data indicate significant wall slip effects which have been analysed using the classical Mooney method, the Jastrzebski variant and one based on Tikhonov regularization. The latter approach yields 'most convincing results', including a previously unreported region of shear thickening at very high shear rates of ~ 3000 s-1 for the model ice cream foam, when the capillary number indicates a possible transition in the flow around bubbles from domination by interfacial effects to viscous effects. Viscous heating effects were observed at relatively low shear rates for the commercial ice cream, but not the model ice cream foam. This was attributed to the melting of the ice crystal phase in the commercial ice cream, and, hence, absent from the model ice cream foam.

Cite this publication as follows:
Martin P, Odic K, Russell A: Rheology of commercial and model ice creams, Appl. Rheol. 18 (2008) 12913.

Effectiveness of drag reduction by small addition of a surfactant in the turbulent flow of water depends on the structure and concentration of the additive, temperature of the solution and turbulence intensity, possible flow disturbance by a mechanical obstacle and the content of ions in water, but also on the age of the surfactant solution.We show how important aging effects are in connection with total surfactant concentration, in particular how rheological parameters of the drag reducing solution change with time.

Cite this publication as follows:
Mik V, Myska J, Chara Z, Stern P: Durability of a Drag Reducing Solution, Appl. Rheol. 18 (2008) 12421.

The XVth International Workshop on Numerical Methods for Non-Newtonian Flows (XVth IWNMNNF 2007) was held on the island of Rhodes, Greece, in June 6 - 10, 2007. Since their inception in 1979, in Providence, Rhode Island, USA, the workshops are rotated biennially between North America and Europe. This was the first time the meeting was held in Greece. Rhodes Island was a proper destination, as the meetings have come a full circle after almost 30 years of frantic activity, which have seen workshop meetings in castles, lakes, islands, seasides. Rhodes, as the capital of the Dodecanese Islands, combines all of the above, and has been a place of tourism and holidays since antiquity. The XVth IWNMNNF was by all measures a truly international event, drawing around 60 scientists and engineers from 18 countries around the world. The Workshop included a plenary lecture by Roger Tanner, from University of Sydney, Australia, and 7 thematic sessions. [more]

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Mitsoulis E, Mavrantzas VG: Numerical Methods for Non-Newtonian Flows - XVth IWNMNNF 2007, Appl. Rheol. 17 (2007) 354.

A newly designed and constructed sliding plate rheometer is used to measure the high frequency (210 Hz) linear viscoelastic properties of two model polymers: polybutene (PB) and polydimethylsiloxane (PDMS). Using well-known rheological models, extrapolations of the viscoelastic measurements obtained on a rotational parallel plate rheometer to a frequency of 210 Hz are used to assess the performance of the high frequency sliding plate rheometer. Good agreement between the extrapolated and measured data demonstrates the ability of the sliding plate rheometer to measure the high frequency rheological properties of both Newtonian and shear-thinning materials.

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Braybrook CA, Lee JA, Bates PJ, Kontopoulou M: Development of a Sliding Plate Rheometer to Measure the High Frequency Viscoelastic Properties of Polymer Melts, Appl. Rheol. 17 (2007) 62563.

We apply the Landmark Paper Index (LPI), calculate and analyze indices for all papers published in rheological Journals (η-Journals') between 1991 and 2007. We discuss the effect of formal criteria on the LPI.

Cite this publication as follows:
Kroger M: Landmark paper index: Application to rheological (η) journals, Appl. Rheol. 17 (2007) 66494.

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Wiklund J: The Nordic Rheology Society Conference 2007, Appl. Rheol. 17 (2007) 301.

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Ruddle J: Australian Centre for Geomechanics (ACG) Rheology Workshop 2007, Appl. Rheol. 17 (2007) 299.

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Schweizer T: Structure and rheology of molten polymers (J.M. Dealy, R.G. Larson), Appl. Rheol. 17 (2007) 258.

The influence of the molecular structure of the polymer matrix and filler loading on the entrance pressure loss of polyethylene/ wood flour composites has been investigated in this research by means of a capillary rheometer equipped with an orifice die. The entry flow of talc- and glass-filled polyethylene composites has been investigated as well. It was found that the entrance pressure loss of wood filled polyethylene composites greatly increased with increasing the wood flour loading. Talc and solid glass spheres also increase the entrance pressure loss, however not as much as wood flour. It was also observed that composites based on narrow molecular weight distribution (MWD) resins exhibited larger entrance pressure loss than the broad MWD and branched polyethylene based ones. It was concluded that measurements of the entrance pressure loss reveal some interesting features of the polymer-filler interactions and could provide significant insights in the processing of highly filled polymer melts.

Cite this publication as follows:
Hristov V, Vlachopoulos J: A Study of Entrance Pressure Loss in Filled Polymer Melts , Appl. Rheol. 17 (2007) 57191.

Self-Compacting Concrete is a new type of concrete which is more liquid compared to traditional concrete and which does not need any form of external compaction. As a result this type of concrete is suitable for a new placing technique: pumping SCC from the bottom in the formwork and letting it rise in the formwork due to the applied pressure. In order to understand the phenomena occurring during pumping operations, the rheological properties of SCC must be investigated and controlled. Tests have been performed with two different rheometers, which are described in this paper. For the Tattersall Mk-II rheometer, a calibration procedure has been worked out to eliminate secondary flows in the rheometer.Test results indicate that SCC is a thixotropic liquid, having a yield stress, showing shear thickening and having varying properties in time due to the occurring chemical reactions. In this paper, the time dependent effects will not be described. When trying to apply a rheological model to the obtained results, only the modified Bingham model seems appropriate. Applying the Bingham model results in the generation of negative yield stresses while the Herschel-Bulkley model has a parameter with a variable dimension and has a maJor mathematical restriction. The rheological properties of fresh SCC can be described with the modified Bingham model. A suitable parameter to describe shear thickening is defined as the ratio of the second order term in the shear rate of the modified Bingham model to the linear term (= c/μ).

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Feys D, Verhoeven R, DeSchutter G: Evaluation of time independent rheological models applicable to fresh Self-Compacting Concrete, Appl. Rheol. 17 (2007) 56244.

A tank-tube viscometer and its novel viscosity equation were developed to determine flow characteristics of non-Newtonian fluids. The obJective of this research is to test capabilities of the tank-tube viscometer and its novel non-Newtonian viscosity equation by characterizing rheological behaviors of well-known polyethylene oxide (MW 8000000) aqueous solutions as non-Newtonian fluids with 60-w% sucrose aqueous solution as a reference calibration fluid. Non-Newtonian characteristics of 0.3 - 0.7 wt% polyethylene oxide aqueous solutions were extensively investigated with the tank-tube viscometer and its non-Newtonian viscosity equation over the 294 - 306 K temperature range, and 55 - 784 s-1 shear rate range. The 60-w% sucrose aqueous solution was used as a reference/calibration fluid for the tank-tube viscometer. Dynamic viscosity values of 60 w% sucrose aqueous solution were determined with the calibrated tank-tube viscometer and its Newtonian viscosity equation at 299.15 K, and compared with the literature values.

Cite this publication as follows:
Kwon KC, Park Y, Floyd T, Vahdat N, Jackson E, Jones P: Rheological Characterization of Shear-Thinning Fluids with a Novel Viscosity Equation of a Tank-tube Viscometer, Appl. Rheol. 17 (2007) 51413.

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Coussot P, Barrat J: Flow in Glassy Systems. European School of Rheology, Appl. Rheol. 17 (2007) 228.

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Embery J: A Feast of Polymer Physics , Appl. Rheol. 17 (2007) 226.

Nowadays it is necessary to perform experimental measurements to compare with numerical calculations. In this study we focus on different aqueous solutions which are tested to obtain in the same time a rheological blood like fluid and particular optical properties for laser measurements (particle image velocimetry (PIV) or laser Doppler velocimetry (LDV)). Using viscometric tests we show that the non Newtonian behavior of blood is reached by adding xanthan gum in aqueous glycerol and aqueous potassium thiocyanate solutions. Optical properties are directly achieved by modifying glycerol or thiocyanate potassium concentrations. Indeed we proove using refractometric measurements that the addition of xanthan gum does not affect the value of the refractive indexes. Finally,we can prepare an optical blood like fluid adapted to cardiovascular studies by adJusting the proportion of the different components.

Cite this publication as follows:
Benard N, Jarny S, Coisne D: Definition of an experimental blood like fluid for laser measurements in cardiovascular studies., Appl. Rheol. 17 (2007) 44251.

We present results from a new approach to the study of multicomponent gels, which allows independent investigation of the effect of phase volume and droplet size of the dispersed phase on the mechanical properties of the mixed gel composites. The method involves preparation of agarose microgels with different sizes, which are then embedded in maltodextrin gel matrices with different gel strengths. The effects of both phase volume and droplet size on composite properties are dependent on the phase modulus ratio. The higher the phase modulus ratio, the larger is the reinforcement effect and the effect of droplet size on mechanical properties of the maltodextrin/agarose composites. The observed behaviour was compared with literature models for the behaviour of composite materials.

Cite this publication as follows:
Loret C, Frith WJ, Fryer PJ: Mechanical and structural properties of maltodextrin/agarose microgels composites, Appl. Rheol. 17 (2007) 31412.

We describe methodology of laser Doppler forced vibrology (LDFV) applied to texture assessment of soft agricultural products. The method is applied to a melon. The lowest frequency resonant peak (mode M0) is used for corrections of the whole amplitude frequency plot expressed in relation to the forcing deformation level. The main differences between vibrology in vertical and horizontal laser positions are described. Missing and/or degeneration of some modes in the laser horizontal position are explained. Peak analysis of the results obtained reveals the parameters connected with information on internal damping, i.e. internal viscosity. Modulus of elasticity is calculated either from the peak frequency of the M1 mode or by a new method from the M0 peak frequency. The modulus of elasticity of the latter method is nearly one order higher and is more variable than the former probably because the M0 mode is related to physical properties of the surface of the melon in contact with the vibrating table. Fine structure of the skin can lead to possible degenerated forms with more sub-peaks.

Cite this publication as follows:
Blahovec J, Akimoto H, Sakurai N: Laser Doppler Forced Vibrology of Soft Agricultural Products, Appl. Rheol. 17 (2007) 25111.

The rheological behavior of a fugitive organic ink tailored for direct-write assembly of 3D microfluidic devices is investigated. Rheological experiments are carried out to probe the shear storage and loss moduli as well as the complex viscosity as a function of varying temperature, frequency and stress amplitude. Master curves of these functions are assembled using time-temperature superposition. The fugitive ink, comprised of two organic phases, possesses an equilibrium shear elastic modulus nearly two orders of magnitude higher than that of a commercial reference ink at room temperature and a peak in the relaxation spectrum nearly six orders of magnitude longer in time scale. The self-supporting nature of extruded ink filaments is characterized by direct video imaging. Comparison of the experimentally observed behavior to numerical predictions based on Euler-Bernoulli viscoelastic beam analysis yield excellent agreement for slender filaments.

Cite this publication as follows:
Therriault D, White S, Lewis J: Rheological Behavior of Fugitive Organic Inks for Direct-Write Assembly, Appl. Rheol. 17 (2007) 10112.

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Rheological Societies: Society's Site Mar 2007 - Aug 2007, Appl. Rheol. 17 (2007) 52.

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Takimoto J: The 22nd annual meeting of the polymer processing society, Appl. Rheol. 17 (2007) 44.

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Chhabra R, Slatter P: First Conference of the Southern African Society of Rheology (SASOR), Appl. Rheol. 17 (2007) 41.

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Cheneler D: Introduction to Polymer Viscoelasticity (M.T. Shaw, W.J. MacKnight), Appl. Rheol. 17 (2007) 10.

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Karam JF, Naccache M: III Brazilian Conference on Rheology, Appl. Rheol. 16 (2006) 342.

We define a Landmark Paper Index (LPI), calculate and analyze indices for all papers published in rheological Journals ('η-Journals') between 1990 and 2006. This paper offers some information about the criteria influencing the impact of publications on the (scientific) community. In opposite to the well known Impact Factor (Journal sensitive) or the number of citations (article sensitive, publication year insensitive) the LPI helps to identify established and potential breakthrough contributions by considering the number of citations per year after publication, in a way which does not overestimate the few, highly cited, articles when performing averages. We discuss the effect of formal criteria on the LPI.

Cite this publication as follows:
Kroger M: Landmark Paper Index: Definition and Application to Rheological (η-)Journals, Appl. Rheol. 16 (2006) 329.

The lubricated semi-hyperbolic die has been proposed as a technique for generating uni-axial extensional flow and, hence, as a device for measuring elongational viscosity. Two methods for extracting extensional viscosity data for polymer melts in laminar flow from this device have been proposed and are evaluated here. Following the approach proposed by Collier and coworkers, values of the transient extensional viscosity, ηc+, obtained from a non-lubricated semi-hyperbolic (SHPB) die for several polyethylene (PE) melts were found to be considerably higher than values obtained by means of the Münstedt type device. Furthermore, the values of ηc+ obtained from the SHPB die were considerably higher than the strain averaged values of ηc+ which Everage and Ballman proposed would be obtained from a lubricated SHPB. The pressure drop across a SHPB die was estimated assuming resistance was all due to wall shear (using the lubrication approximation) for two PE resins. In the case of low density PE (LDPE) the values agreed to within 20% of the measured values suggesting that shear effects at the die wall were dominating the pressure drop and not extensional stresses. An analysis was carried out which showed that in the presence of lubrication the conditions for which the values of ηc+ obtained from the SHPB would be relatively accurate (Hencky strains > 5.0).

Cite this publication as follows:
Baird DG, Huang J: Elongational Viscosity Measurements Using A Semi-Hyperbolic Die, Appl. Rheol. 16 (2006) 312.

Since its start in 1970, the international conference on Deformation, Yield and Fracture of Polymers has been held every three years in Churchill College, Cambridge, UK. Amongst the 'mechanical properties of polymers' aficionados these meetings have become known as the 'Churchill' conferences, an event that has been established as the leading conference on its subJect world wide. ...

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Govaert LE, Meijer HEH: DYFP2006, the 13th int. conference on deformation, yield and fracture of polymers, Appl. Rheol. 16 (2006) 290.

The current computer simulation based study aims to elucidate the complex role that the state of aggregation and morphology of the food materials plays in determining their transport behaviour. Using Brownian dynamic simulations, applied to colloidal systems, we simulate the compression of two different dense layers of nanoparticles (with reversible and irreversible bonds), at interface, at three different compression rates. We determine the desired transport coefficient for these structures using a novel technique, originally proposed by Torquato and Kim (1990). This method allows us to consider complex structures in our study, for which calculations of effective transport coefficients using conventional methods, like finite elements and finite difference, would be relatively difficult. We first validate our algorithm by comparing its results with those of exact calculations, for different regular lattices. Our results are in excellent agreement with the theory. The variation in the transport coefficient of nano-particle monolayers during the compression, are also correlated with the build up of stress and changes in the structure of the films.

Cite this publication as follows:
Courtois P, Ettelaie R, Chen J: Numerical Studies of Transport Properties in Heterogeneous Food Systems, Appl. Rheol. 16 (2006) 275.

In this paper we describe the rheological behaviour of Ca2+-induced cold-set gels of whey protein mixtures. Coldset gels are important applications for products with a low thermal stability. In previous work [J. Agric. Food Chem. 54 (2006) 4229], we determined the state diagram for whey protein mixtures that were heated for 10 h at pH 2 at 80°C. Under these conditions, the maJor whey protein, β-lactoglobulin (β-lg), forms fibrils. When whey protein mixtures are heated at protein concentrations in the liquid solution regime of the state diagram, cold-set gels can be formed by adding Ca2+ ions at pH 7. We studied the rheological behaviour of cold-set gels for various sample compositions for whey protein mixtures. When keeping the total whey protein concentration constant, the elastic modulus, G., for the cold-set gels decreased for increasing α-lactalbumin and bovine serum albumin ratios, because less material (blg fibrils) was available to form a gel network. In the cold-set gels the interactions between the β-lg fibrils induced by the calcium ions are dominant. The β-lg fibrils are forming the cold-set gel network and therefore determine the gel strength. α-Lactalbumin and bovine serum albumin are not incorporated in the stress-bearing structure of the gels.

Cite this publication as follows:
Bolder S, Hendrickx H, Sagis L, vanderLinden E: Ca2+-induced cold-set gelation of whey protein isolate fibrils, Appl. Rheol. 16 (2006) 258.

When two biopolymers are mixed together, they will normally phase separate to give two distinct phases. If the biopolymers are gelled during this phase separation, for instance by reducing the temperature, one phase is trapped in this other one and an emulsion-like composite structure is obtained. In this study, we investigated the effect of volume fraction and droplet size of this dispersed phase on the mechanical properties of maltodextrin/ agarose gel composites, where agarose is the dispersed phase. Mechanical properties of the different composites were investigated under large deformation using a rheometer with a vane geometry. These composites were also observed by confocal microscopy, allowing conclusions to be drawn regarding the microstructural origins of the observed mechanical behaviour.

Cite this publication as follows:
Loret C, Frith WJ, Fryer PJ: Mechanical and structural properties of maltodextrin/agarose gel composites, Appl. Rheol. 16 (2006) 248.

In this contribution, a brief review is given of the dynamics of emulsions in microconfined shear flow. The interest in confined flow is triggered by the increasing importance of microfluidic applications in the processing industries. In a first part, some important aspects of confinement on single droplet dynamics are highlighted. The validity of the conclusions drawn from this part are subsequently applied to more concentrated systems. It is shown that microconfined emulsions can exhibit rich dynamics, and can display some peculiar morphologies.

Cite this publication as follows:
Vananroye A, VanPuyvelde P, Moldenaers P: Morphology development during microconfined flow of viscous emulsions, Appl. Rheol. 16 (2006) 242.

The measurement of the shear rheology of concentrated particulate suspensions is important to a range of mixing, pumping and flow operations. The use of a four or six bladed vane attached to a rheometer in an open cup is a popular technique to achieve a rheological characterisation. A problem occurs in the use of automated software with a number of rheological devices for yield stress materials. A torque auto zero default causes the torque at the start of a test to be ignored, and can result in significant errors and underestimation of the yield stress or rheological response of the suspension. The potential effect of using a torque auto zero default is demonstrated for a concentrated particulate suspension of nickel laterite.

Cite this publication as follows:
Fisher DT, Boger DV, Scales PJ: Measurement errors in yield stress rheometry that arise from torque auto zero, Appl. Rheol. 16 (2006) 206.

The effect of viscoelasticity on multilayer polymer extrusion is discussed. In these coextrusion processes predetermined patterns are created with a remarkable breadth of complexity even in geometrically simple dies via elastic rearrangements caused by the second-normal stress differences. A computational method is offered, based on the mapping method, which quantitatively describes the flow-induced patterns. Besides that the results are esthetically beautiful, they are also relevant for practice, since process and die design optimization is now possible. Not only to minimize interface distortion, but potentially also to deliberately create new processes and products based on this flow-induced patterning of polymers.

Cite this publication as follows:
Anderson PD, Dooley J, Meijer HEH: Viscoelastic effects in multilayer polymer extrusion, Appl. Rheol. 16 (2006) 198.

In this work we investigate the rheological behaviour of macroscopic buoyant hard spheres dispersed in a shearthinning suspending fluid. We focus on the phenomenological study of the influence of the shear-thinning behaviour of the suspending medium on the effective apparent suspension viscosity at different volume fractions. In the oil industry, the effective viscosity concept is widely used and very useful to quickly characterize a change of viscosity due to an increase of the solid content. Viscosity measurements are compared to the effective viscosity of a suspension of hard spheres in an Ostwald fluid. The power law index of the suspending fluid is shown, both experimentally and theoretically, to influence strongly the volume fraction dependence of the suspension effective viscosity. All experimental results are shown to be quite correctly plotted on a master curve, with only one adJustable parameter, the maximum packing fraction φ_m. The best fit is obtained for φ_m = 0.57, corresponding to the theoretical maximum random packing volume fraction.

Cite this publication as follows:
Peysson Y, Aubry T, Moan M: Phenomenological Approach of the Effective Viscosity of Hard Sphere Suspensions in Shear-Thinning Media, Appl. Rheol. 16 (2006) 145.

The rheological behaviour of PVC plastisols composed of a blend of suspension and micro-suspension resins in different proportions was investigated. The present work was mainly focused on the variation of the zero shear viscosity versus the concentration of the extender resin. Hence, the packing fraction Fm was evaluated using the Krieger-Dougherty equation. These experiments confirmed the maJor influence of particle size distribution concerning the decrease of viscosity for concentrated suspensions. In addition, a model based on the porosity model developed by Ouchiyama et al. (Ouchiyama N, Tanaka T: "Porosity estimation for random packings of spherical particle", Ind. Eng. Chem. Fundam. 23 (1984) 490-493) to predict the packing fraction in the case of multimodal lattices was successfully applied to our PVC plastisols formulations.

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Laine C, Cassagnau P: Prediction of Zero Shear Viscosity of Poly (Vinyl Chloride) Plastisols, Appl. Rheol. 16 (2006) 136.

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Fischer P, Kroger M: Patents Review (June 2006), Appl. Rheol. 16 (2006) 164.

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Prasad K: Rheology for Chemists - An Introduction (Jim W Goodwin, Roy W Hughes), Appl. Rheol. 16 (2006) 69.

The purpose of this paper was to re-evaluate the novel rheological method of Crosby et al. [J. Rheol. 46 (2002) 401] to characterise long chain branching (LCB) in polyethylenes (PE) using the rheology of concentrated solutions. The feasibility of this dilution method centred on knowing the class of branched material and the molecular tube theory-based technique for the determination of two topological parameters (n, bU), where n is the number of entanglements between branch points while bU is the probability of meeting a branch point when tracing along the molecule from a random monomer against the direction of polymerisation. This paper proposes new possible approaches to calculate the two topological parameters (n, bU) set for metallocene polyethylenes (mPE), and their ambiguity discussed, as the results are dependent on the approach taken, though the previous authors mentioned only one. In addition, their approach requires an input value of LCB/1000C obtained from the standard analytical solution (SEC-V or SEC-LALLS) methods, hence, until now, without proper demonstration of the potential advantage of the dilution rheology method for LCB characterisation, as the main premise of their published article was to characterise the degree of LCB via rheological measurements without recourse to other methods of LCB characterisation.

Cite this publication as follows:
Chai CK, Ang SC: An Evaluation of Dilution Rheology for the Characterization of Long Chain Branching of Polyethylenes, Appl. Rheol. 16 (2006) 90.

Of the torsional drag-flow experiments, the hands-down winner for simplicity and ease of use is that using parallel- plate fixtures. This geometry is highly flexible, allowing custom modification of plate size and material, and is easily adaptable for optical use and the application of electric fields. However, its nonuniform flow is a maJor encumbrance for measuring nonlinear response. In 1987, Cross and Kaye offered a simple and clever solution for this problem, which essentially states that one assumes the sample is Newtonian, but the shear rate assigned to the observed ''Newtonian'' viscosity is 3/4ths of the rim shear rate . This shift factor arises from the use of Gaussian integration over radius of the nonlinear stress profile. Recent re-examination of the Cross-Kaye rule indicates that there may be a more accurate rule of thumb with the shift factor being 0.8 instead of 0.75 (4/5 instead of 3/4). However, for complex materials, the real question is how much useful information is covered up by this approach vs. the traditional differentiation of the integral to account for the stress profile. We have attempted to answer this question using a selection of nonlinear measurements on an AB block copolymer solution that is rheologically complex.

Cite this publication as follows:
Shaw MT, Liu ZZ: Single-point Determination of Nonlinear Rheological Data from Parallel-Plate Torsional Flow, Appl. Rheol. 16 (2006) 70.

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Ratajczak P: Third International Conference on Engineering Rheology ICER 2005, Appl. Rheol. 16 (2006) 110.

The yielding behavior of two model electrorheological suspensions of uncoated silica particles and silica coated with polyaniline base in silicone oil using controlled shear rate and controlled shear stress experiments has been analyzed. The results demonstrate that unlike the uncertain dynamic yield stress values estimated from the results obtained in the former mode by extrapolation of the unsteady shear stresses to zero shear rate, the controlled shear stress measurement permits to detect sensitively the region starting from the initial rupture of particle chain structure in the electric field at rest corresponding to a static yield stress and ending in total breakage of suspension structure at a breaking stress. The latter quantity can be detected with a good accuracy and proved to be a reliable criterion of the stiffness of electrorheological (ER) structure.

Cite this publication as follows:
Pavlinek V, Saha P, Perez-Gonzalez J, DeVargas L, Stejskal J, Quadrat O: Analysis of the Yielding Behavior of Electrorheological Suspensions by Controlled Shear Stress Experiments, Appl. Rheol. 16 (2006) 14.

Cite this publication as follows:
Boek ES, Padding JT: CECAM Workshop on Structure and Rheology of Self-Assembling and Aggregating Colloidal Suspensions: Theory, Simulation and Experiment, Appl. Rheol. 16 (2006) 35.

The Impact Factor of a Journal is a quantitative way of assessing its worth and relevance to the academic community it serves. Many librarians see the ratio between Impact Factor and price as a suitable yardstick by which to measure the value of their collections. In addition, the research assessment exercises which, in many countries, are now being carried out on a more formal basis mean that authors submitting original research must publish it in a Journal with the highest perceived worth possible in order to secure future funding, Job promotions and peer recognition. It has been suspected [T. Opthof, Cardiovasc. Res. 33 (1997) 1; J. Stegmann, Nature 390 (1990) 550], however, that a particular author's impact is not much related to the Journals in which her/he publishes. As will be demonstrated in this letter, the impact of articles published in rheological Journals is largely influenced by criteria such as length of article, number of authors, number of cited references.

Cite this publication as follows:
Kroger M: Publication Specific Impact of Articles Published by Rheological Journals, Appl. Rheol. 15 (2005) 406.

Blood flow rheology is a complex phenomenon. Presently there is no universally agreed upon model to represent the viscous property of blood. However, under the general classification of non-Newtonian models that simulate blood behavior to different degrees of accuracy, there are many variants. The power law, Casson and Carreau models are popular non-Newtonian models and affect hemodynamics quantities under many conditions. In this study, the finite volume method is used to investigate hemodynamics predictions of each of the models. To implement the finite volume method, the computational fluid dynamics software Fluent 6.1 is used. In this numerical study the different hemorheological models are found to predict different results of hemodynamics variables which are known to impact the genesis of atherosclerosis and formation of thrombosis. The axial velocity magnitude percentage difference of up to 2 % and radial velocity difference up to 90 % is found at different sections of the T-Junction geometry. The size of flow recirculation zones and their associated separation and reattachment point's locations differ for each model. The wall shear stress also experiences up to 12 % shift in the main tube. A velocity magnitude distribution of the grid cells shows that the Newtonian model is close dynamically to the Casson model while the power law model resembles the Carreau model.

Cite this publication as follows:
Shibeshi SS, Collins WE: The Rheology of Blood Flow in a Branched Arterial System, Appl. Rheol. 15 (2005) 398.

We report on the design and implementation of an evaporation blocker for cone-plate and plate-plate geometries. In addition to minimizing sample evaporation by trapping the saturated vapor inside a sample chamber, an important feature of the evaporation blocker is the suppression of solvent transport through condensation. Validation tests with DI-water, hydrogels, and colloidal suspensions demonstrate that the new accessory reduces solvent evaporation significantly more than commercially available environmental control chambers. Experiments were also performed to show that the evaporation blocker enables a variety of experiments on thermoresponsive complex fluids that were previously impossible, and provide new insight into the molecular organization of these materials. The evaporation blocker was specifically designed for an Anton Paar MCR rheometer, but the fundamental principles are widely applicable.

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Sato J, Breedveld V: Evaporation Blocker for Cone-Plate Rheometry of Volatile Samples, Appl. Rheol. 15 (2005) 390.

Cite this publication as follows:
Richtering W: Fundamentals of Interface and Colloid Science: Volume IV: Particulate Colloids and Volume V: Soft Colloids (J. Lyklema), Appl. Rheol. 15 (2005) 310.

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Peters F: CECAM Workshop on Modeling and Simulation of Entangled Polymeric Liquids, Appl. Rheol. 15 (2005) 240.

Cite this publication as follows:
Stange J: Workshop Rheology and Processing of Polymers, Appl. Rheol. 15 (2005) 238.

Oxide ceramic masses are used for catalysts and catalyst carriers. For a reliable processing hydrocolloids (e. g. cellulose) are usually added in order to decelerate demixing phenomena. Oxide ceramic masses react to simple shearing with hardening (peptisation: increase of the shear stress with the shear deformation) [1]. The present study analyses, if an ultrasonic treatment has also an impact on the structure, the shelf-life (in the green state), the correlated flow behaviour of oxide ceramic masses and presumably (not tested) the mechanical properties in the hardened, sintered state. The idea of using ultrasonic treatment is to change the microstructure (see below) and, therefore, to minimise or even give up the standard addition of stabilizers to minimize demixing in aqueous oxide ceramic suspensions. Besides the additional costs of an extra process unit, stabilisers cause often deteriorated mechanical properties (porosity, crack behaviour) of the ceramics in the hardened state after the sintering. Therefore, pump experiments (apparent viscosity), oscillatory (G´ and G´´) and steady shear experiments (h), particle-size analysis (particle-size distribution, agglomerate strength), light microscopy, decanting experiments and pH-determinations have been performed. The obtained results show, that the hardening of the apparent viscosity (derived from the flow) during pump experiments with simultaneous ultrasonic treatment in a flow cell is combined with an increase of the fine fraction, the formation of enlarged, but smoother agglomerates, the change of the pH-value and the evolution of a three-dimensional network (gelling). All these processes increase both the amount of bound/immobilised (chemically or physically bound by or onto the solidsurfaces) and of retained water (interior of agglomerates and/or the pores of the flowand ultrasonic-induced network). This means that the volume fraction of the rheologically "free" water decreases and simultaneously the effective solid volume fraction increases. With respect to the concept of the rheologically effective solid fraction this is combined with an increasing viscosity. At the same time the tendency of demixing decreases significantly. Thus, by an appropriate combination of shear flow and ultrasonic treatment, the aqueous oxide ceramic suspensions are stabilised and a reliable processing of the initially problematic solid/fluid mixtures can be realised without stabilisers (eluding their negative consequences with respect to the quality of the sintered state).

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Gotz J, Rewese L, Walch M, Geissler A: Influence of an Ultrasonic Treatment on the Structure and Flow Behaviour of Oxide Ceramic Masses, Appl. Rheol. 15 (2005) 204.

Cite this publication as follows:
Fischer P, Kroger M: Patents Review (June 2005), Appl. Rheol. 15 (2005) 182.

The effect of high ac electric fields upon a liquid crystalline polymer solution, poly(n-hexyl isocyanate) in p-xylene, is examined. The results show that the solutions exhibit an increase in rheological properties proportional to the strength of the field at concentrations well below those exhibiting liquid crystalline behavior. The effects of frequency and field strength are examined as a means to explain this previously unreported phenomenon.

Cite this publication as follows:
Menna TJ, Filisko FE, Lynch RA: Effect of Electric Fields on the Rheological Properties of the Isotropic Phase of phic/p-Xylene Solutions, Appl. Rheol. 15 (2005) 172.

Exponential integral functions were fitted to relaxation data obtained from tensile and shear loading of an asphalt-sand mixture at different temperatures. This approach yields a better fit to the experimental data than the traditional Prony series and provides physical insight into essential characteristics of the relaxation processes that govern the asphalt-sand mixture. We expect that using this model beyond the time range covered by the experimental data would result in a significantly better representation of the material behavior than would extrapolation of the Prony series fit.

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Koenigsberg W, Selverian JH: Zone Method for Representing Relaxation Characteristics of Viscoelastic Materials, Appl. Rheol. 15 (2005) 160.

A new model for mean velocity profile of turbulent water flow with added drag-reducing surfactants is presented in this paper. The general problem of drag due to frictional resistance is reviewed and drag reduction by the addition of polymers or surfactants is introduced. The model bases on modified Prandtl's mixing length hypothesis and includes three parameters, which depend on additives and can be evaluated by numerical simulation from experimental datasets. The advantage of the model in comparison with previously reported models is that it gives uniform curve for whole pipe section and can be determined for a new surfactant with less necessary measurements. The use of the model is demonstrated for surfactant Habon-G as an example.

Cite this publication as follows:
Krope A, Krope J, Lipus LC: A Model for Velocity Profile in Turbulent Boundary Layer with Drag Reducing Surfactants, Appl. Rheol. 15 (2005) 152.

Magnetorheological fluids (MRFs) show a high but reversible rise of the viscosity upon application of an external magnetic field. This effect can be utilized in controllable friction dampers where the MR fluid flows through a gap with a adJustable magnetic field. The change in the magnitude of the magnetic field leads to a change of the viscosity of the fluid which in turn effects the pressure drop in the system. So the damping force can be controlled by the magnitude of the external magnetic field. This energy dissipation leads to a rise of the damper temperature. For designing those dampers it is vital to know the influence of the geometry, which influences the magnetic field strength, as well as the flow properties and the temperature dependence of the magnetorheological effect. An approach to the solution of this problem is shown by using an Arrhenius relationship, where the fluid viscosity is a function of the shear rate, the magnetic field and the temperature. The aim of the here presented research is to show how the fluid behavior can be simply modeled for use in CFD codes to design dampers or other applications.

Cite this publication as follows:
Zschunke F, Rivas R, Brunn PO: Temperature Behavior of Magnetorheological Fluids, Appl. Rheol. 15 (2005) 116.

The calibration of the temperature control unit of a rotational rheometer with a hood oven is shown. The calibration technique shown for a Paar-Physica rheometer can be adapted to any rheometer with hood oven (indirect heating). The temperature of the bottom fixed plate and the air bearing suspended cone or plate are measured independently. By keeping the amount of venting gas constant, the set temperature of the hood oven is adJusted to reach a minimum gradient across the measuring gap. The calibration procedure is optimized to keep the oven as close as possible to the measuring position.

Cite this publication as follows:
Schweizer T: Temperature Calibration of Rotational Rheometers with Electrically Heated Tools and Hood Oven, Appl. Rheol. 15 (2005) 112.

In order to characterise the structure and flow behaviour of model chocolate systems Nuclear Magnetic Resonance (NMR) and rheometry were used to determine the T1 - and T2 - NMR relaxation times and their corresponding flow functions. T1 and T2 characterise the molecular mobility of fluids and correlate with both the zeroshear- rate and infinity viscosity of various chocolate model systems (determined with rotational rheometry and capillary rheometry). Based on this correlation, NMR provides the possibility to determine characteristic viscosities of chocolate masses by means of NMR-relaxation experiments. The viscosities of chocolate masses are important process parameters, as they are used for quality control of the production process. An online process viscosimetry via T2 relaxation would allow the installation of an efficient process control and, thus, a process automation. This NMR application with comparatively short measuring times is especially interesting for disperse systems where the use of conventional rheometric techniques may cause large errors. The only prerequisite for the measurement of the viscosities using NMR is a previous calibration. This was performed with the help of rotational and capillary rheometry. The NMR self-diffusion experiments are especially appropriate to characterise the influence of emulsifiers on the structure and the flow behaviour of chocolate masses.

Cite this publication as follows:
Gotz J, Balzer H, Hinrichs R: Characterisation of the Structure and Flow Behaviour of Model Chocolate Systems by Means of NMR and Rheology, Appl. Rheol. 15 (2005) 98.

There is often a need to perform rheological tests on dilute polymeric liquids at a time long after their initial preparation, for example if a more sensitive or novel method of measuring a material property (such as uniaxial/ biaxial extensional viscosity or second normal-stress differences) becomes available. An inexpensive method of storing such fluids which prevents any form of deterioration (e.g. bacteriological) would therefore be of great value. This study explores the potential of freezing as that storage process by investigating whether the freezethaw process itself leads to rheological changes. The rheological properties of three polymeric liquids: 0.25 % xanthan gum, 0.125% polyacrylamide and a 0.1 %/0.1 % carboxymethylcellulose / xanthan gum blend commonly used in non-Newtonian fluid flow studies were determined in both shear and oscillation before and after a freeze-thaw process. Within the uncertainty of the rheometer used, the rheological properties of the polymers studied were found to be unaffected by the freeze-thaw process leading to the conclusion that this storage method is indeed a practical possibility.

Cite this publication as follows:
Escudier MP, Clement-Evans J, Poole RJ: Freezing as a Storage Process for Aqueous Polymer Solutions, Appl. Rheol. 15 (2005) 90.

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Jongschaap R J J : Beyond Equilibrium Thermodynamics (H.C. Öttinger), Appl. Rheol. 15 (2005) 88.

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Rheological Societies, Petrie CJS, Mielke W, Coussot P, Kissi NE, Fischer P, Mavrantzas VG, Grizzuti N, Jarvela P, Wanger MH: Society's Site Mar 2005 - Aug 2005 , Appl. Rheol. 15 (2005) 59.

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Rodrigue D, Heuzey M-C, Dubois C, DeKee D: Prof. Pierre J. Carreau 65th Birthday Symposium, 2004, Montreal, Canada, Appl. Rheol. 15 (2005) 48.

Cite this publication as follows:
Kroger M, Moldenaers P: Rheology and Microstructure of Complex Fluid Systems. Symposium in Honour of Prof. Jan Mewis, Appl. Rheol. 15 (2005) 46.

Viscosity measurements of a suspension of cornstarch in silicone oil, at several concentrations and subJect to different electrical field strengths, were conducted. An increase in the apparent viscosity, in correlation with the field strength, which is characteristic of the so-called electrorheological fluids (ERF), was observed. For a given field intensity, the value of the viscosity increases rapidly in the first seconds after the application of the electric field, and then it increases slowly until it finally approaches a saturation value. This behaviour of the apparent viscosity has been related to the microstructure formation due to interactions between dipoles induced by the electric field. Characteristic times, related to structure formation after application of an electric field, are investigated by means of diffuse light transmission and speckle-pattern activity measurements. Two characteristic times were found that should be related to the state of aggregation of the suspended particles: orientation of the non-isotropic particles and later chain formation. These results agree reasonably with that obtained from electrorheological measurements. Microscopic observations of structure formation are also reported.

Cite this publication as follows:
Alanis E, Romero G, Martinez C, Alvarez L, Mechetti C: Characteristic Times of Microstructure Formation in Electrorheological Fluids determined by Viscosity and Speckle Activity Measurements, Appl. Rheol. 15 (2005) 38.

Commercially available, blended methylhydroxyethyl celluloses with similar weight-average molar masses but varying molar mass distributions were characterized by different techniques like steady shear flow and uniaxial elongation in capillary breakup experiments. The determined relaxation times t were then correlated with the absolute molar mass distribution acquired via SEC/MALLS/DRI (combined methods of size-exclusion-chromatography, multi angle laser light scattering and differential refractometer). In order to describe the longest relaxation time of the polymers in uniaxial elongation via integral mean values of the molar mass distribution, defined blends of polystyrene standards with varying molar mass distributions were characterized. The obtained data was scaled via different moments of the molecular weight distribution and could be correlated with the results obtained for the methylhydroxyethyl celluloses.

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Plog JP, Kulicke W-M, Clasen C: Influence of the Molar Mass Distribution on the Elongational Behaviour of Polymer Solutions in Capillary Breakup, Appl. Rheol. 15 (2005) 28.

We investigate the dynamics of the capillary thinning and break-up process for low viscosity elastic fluids such as dilute polymer solutions. Standard measurements of the evolution of the midpoint diameter of the necking fluid filament are augmented by high speed digital video images of the break up dynamics. We show that the successful operation of a capillary thinning device is governed by three important time scales (which characterize the relative importance of inertial, viscous and elastic processes), and also by two important length scales (which specify the initial sample size and the total stretch imposed on the sample). By optimizing the ranges of these geometric parameters, we are able to measure characteristic time scales for tensile stress growth as small as 1 millisecond for a number of model dilute and semi-dilute solutions of polyethylene oxide (PEO) in water and glycerol. If the final aspect ratio of the sample is too small, or the total axial stretch is too great, measurements are limited, respectively, by inertial oscillations of the liquid bridge or by the development of the well-known beads-on-a-string morphology which disrupt the formation of a uniform necking filament. By considering the magnitudes of the natural time scales associated with viscous flow, elastic stress growth and inertial oscillations it is possible to construct an .operability diagram. characterizing successful operation of a capillary breakup extensional rheometer. For Newtonian fluids, viscosities greater than approximately 70 mPas are required; however for dilute solutions of high molecular weight polymer, the minimum viscosity is substantially lower due to the additional elastic stresses arising from molecular extension. For PEO of molecular weight 2 · 106 g/mol, it is possible to measure relaxation times of order 1 ms in dilute polymer solutions with zero-shear-rate viscosities on the order of 2 . 10 mPas.

Cite this publication as follows:
Rodd LE, Scott TP, Cooper-White JJ, McKinley GH: Capillary Break-up Rheometry of Low-Viscosity Elastic Fluids, Appl. Rheol. 15 (2005) 12.

Cite this publication as follows:
Kroger M: An Introduction to Theoretical Chemistry (Jack Simons), Appl. Rheol. 14 (2004) 329.

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Kroger M: Electronic Basis of the Strength of Materials (John J. Gilman), Appl. Rheol. 14 (2004) 328.

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Truscott J: 4th Conference on Modelling and Simulation in Medicine, Appl. Rheol. 14 (2004) 327.

The term |G*|/(1-(1/tand sind)) has been suggested as one of the best candidates for the replacement of the Superpave specification parameter |G*|/sind, which has been found to be inadequate in rating polymer-modified binders for high temperature performance grading. This refinement of the Superpave specification parameter evolved through a theoretical derivation based on fundamental concepts. It was shown to be more sensitive to the variations in the phase angle d than the original Superpave specification parameter. It thus described the unrecovered strain in the asphalt binders more accurately, and hence related to actual field performance data. This article provides a comprehensive treatise of the parameter |G*|/(1-(1/tand sind)) giving details of its derivation, salient features that are attributed to its success, comparison with actual field performance data for validation and a one-on-one comparison with the existing parameter |G*|/sind. It is shown that for all available field data, the parameter |G*|/(1-(1/tand sind)) does a better Job in correlating with the rutting behavior than the parameter |G*|/sind for unmodified as well as modified asphalts. Since it is obtained in the same manner as the parameter |G*|/sind through the determination of |G*| and d from a stress-controlled or strain-controlled dynamic shear rheometer, it means that no retraining of technicians and staff is required and implementation for the use of this parameter is immediate, thereby saving enormous amount of time and money. This parameter has the further advantage of being in a form easily adaptable to modeling, and thereby directly applicable for pavement design purposes.

Cite this publication as follows:
Shenoy A: A Comprehensive Treatise of the High Temperature Specification Parameter |G*|/(1-(1/tan d sin d)) for Performance Grading of Asphalts, Appl. Rheol. 14 (2004) 303.

An orifice flowmeter was used to measure the extensional viscosity of several non-pigmented fluids and paper coating colors containing calcium carbonate as pigment in the context of a Jet coating application. The orifice flowmeter was first calibrated in terms of a dimensionless Euler number versus Reynolds number curve with Newtonian fluids. The calibration curve was then used to determine the apparent extensional viscosity of coating colors. In the strain rate range investigated, all the fluids were found to exhibit strain-thinning and the Trouton ratio of the coating colors was in the range 5 to 20. Jet coating tests were also carried out in order to evaluate the effect of the extensional viscosity on the Jet performance. The extensional viscosity was shown to be a key parameter determining the configuration of the downstream meniscus in the web contact region.

Cite this publication as follows:
Arzate A, Ascanio G, Carreau PJ, Tanguy PA: Extensional Viscosity of Coating Colors and its Relation With Jet Coating Performance, Appl. Rheol. 14 (2004) 240.

Cite this publication as follows:
Richtering W: Physical Properties of Polymers (J. Mark, K. Ngai, W. Graessley, L. Mandelkern, E. Samulski, J. Koenig, G. Wignall), Appl. Rheol. 14 (2004) 239.

Rheological properties of xerographic liquid inks of different concentrations of solid particles have been tested. Generally we have found that viscosity decreases with increasing shear rate, i.e. the system is pseudoplastic as corresponds to the break down of aggregated particles by the applied shear. The viscosity of inks may vary in orders of magnitude depending on solids concentration, reaching up values of ~ 108 Pas for solids concentration of 40 wt%. The existence of a yield critical stress has been discussed and we estimate that it increases exponentially with solids concentration. We have looked for possible differences in the rheological behavior of ink samples obtained either diluting more concentrated inks or drying less concentrated ones. Concentration and dilution of xerographic inks do not change their rheological properties meaning that the microscopic structure of the concentrated dispersion is broken (when diluting) and recovered (when drying) reversibly. On the other hand processed ink (previously subJected to high mechanical and electrostatic stresses) behaves differently than non-processed ink. The properties of processed inks are not totally recovered when diluting, manifesting itself in a higher effective apparent viscosity. This result should be of main concern to liquid ink based printing technologies, for which elimination of waste by recycling processed ink is a maJor goal.

Cite this publication as follows:
Valverde JM, Perez AT, Castellanos A, Viturro RE: Rheological Testing of Xerographic Liquid Inks: A Need for Printing Technology, Appl. Rheol. 14 (2004) 190.

The steady and dynamic shear viscosity of fish muscle protein paste obtained from Alaska pollock surimi at 95%, 90%, 85%, 80%, and 75% of moisture contents were measured in the temperature range of 5°C to 20°C. To estimate the steady shear viscosity at high shear rate from dynamic shear viscosity, the modified Cox-Merz rule was applied by introducing a frequency shift factor. The concentration dependence of zero-shear viscosity showed power-law dependence with an exponent of 3.5, and the universal behavior of viscosity at different protein concentrations was observed by a introducing reduced variables. The Carreau model was applied to describe the shear- thinning behavior of the surimi paste, and the model parameters estimated empirically showed moisture content dependence. The viscous flow behavior was independent of temperature (5°C to 20°C), and addition of starch decreased the flow index and viscosity of the paste, compared to the pure surimi paste.

Cite this publication as follows:
Yoon WB, Gunasekaran S, Park JW: Evaluating viscosity of Surimi paste at different moisture contents, Appl. Rheol. 14 (2004) 133.

The linear viscoelastic regions (L.V.R.) of suspensions of zirconium oxide particles were determined and characterized through the so-called 'critical parameters'. These are the values of shear-stress and strain at the crossover between the linear and the non-linear viscoelastic responses. From these magnitudes, the cohesive energy between the particles is calculated as a function of volume fraction of solids and at different electrolyte concentrations. The oscillatory measurements were carried out using a constant-stress rheometer at a fixed frequency of 1 Hz and increasing shear-stress. The suspensions cover a volume fraction range between 3% - 25% with electrolyte (sodium chloride) concentrations of 10-1 M, 10-2 M, 10-3 M and 10-5 M. Two different kinds of ZrO2 particles were used: commercially obtained -with no defined geometry- and spheres synthesized by us following the method described by Aiken, Hsu and MatiJevic.

Cite this publication as follows:
Megias-Alguacil D: Characterization of the linear viscoelastic region in suspensions of zirconium oxide: Cohesive energy obtained from the critical parameters, Appl. Rheol. 14 (2004) 126.

Changes in the rheological properties of hair shampoo samples differing in the content of Dead Sea (DS) salt were studied. The rheological properties were tested during a 28-day storage period at three different storage temperatures (cold, room temperature and accelerated conditions). Steady rheological tests were performed and the conductivities of the shampoo samples were determined. The parameters of the power law model; the consistency coefficient and the flow behavior index were used to quantify the effect of storage time and temperature on the rheological behavior of hair shampoo in the presence of DS salt. The consistency coefficient of the salt free shampoo samples stored at 8°C and at room temperature decreased with storage time, and the rheological behavior changed from shear thinning to Newtonian. On the other hand, the samples stored at 45°C exhibited a shear thinning behavior, which did not change with storage time. Shampoo samples with 1.5 wt% DS salt content, showed the maximum viscosity and the rheological behavior of the samples did not change with the storage time. An exception were the samples stored at 45°C, which behaved like the salt free samples stored at room temperature. The conductivity of hair shampoo increased linearly with storage time and salt concentration. A discontinuity at a salt concentration of 1.5% was observed. However, the conductivity of hair shampoo increased with increasing the storage temperature.

Cite this publication as follows:
Abu-Jdayil B, Mohameed H, Snobar T, Sa'id A: Rheology and Storage Tests of Dead Sea Shampoo, Appl. Rheol. 14 (2004) 96.

The aim of this paper is to present a new phenomenological rheological model suitable for the description of a wide class of viscoelastic fluids. Classical phenomenological models predict the relation shear viscosity vs. shear rate (or shear stress) for shear-thinning (or thickening) materials exhibiting smooth monotonous passage from the first - upper (lower) - Newtonian plateau to the second - lower (upper) - one. However, present state of non- Newtonian materials used in practice (ranging from aqueous surfactant solutions, bituminous materials, associative polymers, polymer thickeners, lacquers and gels, to some special disperse systems, etc.) evokes the need to describe this - for many materials non-monotonous - relation in the corresponding way, i.e. through the sufficiently simple phenomenological model with a moderate number of parameters. A six-parameter model enabling description of not only monotonous but also non-monotonous course of shear viscosity function against shear rate (stress) is proposed including physical characterisation of the parameters. This model describes not only extreme points (maximum or minimum) but also a possible appearance of intermediate Newtonian plateau or its indication. The meaning and influence of the individual six parameters is documented on the experimental data published in the literature. There is a good agreement of the model proposed with many different experimental data representing different rheological behaviour. The applicability of this model for a wide class of viscoelastic materials is its principal advantage over the hitherto published phenomenological models.

Cite this publication as follows:
David J, Filip P: Phenomenological Modelling of Non-Monotonous Shear Viscosity Functions, Appl. Rheol. 14 (2004) 82.

The yield stress has, since its conception, been a source of fierce and often acrimonious debate. This review article deals with the issue, looking at problems related to the meaning of the definition, timescale of the observation, whether the yield stress is a property of concentrated suspensions or is linked to the strength of coherent network structures. We discuss the problematic nature of how to measure the yield stress, directly or indirectly, and examples of the vane geometry are given. Throughout, absolutist and realist theories and evidence are presented and a consensus is finally drawn. Rheologists should embrace the consequences of the absolutist and realist theories and apply them to their everyday world - whatever the timescale!

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Watson JH: The Diabolical Case of the Recurring Yield Stress, Appl. Rheol. 14 (2004) 40.

Red blood cell aggregation (RBCa) is a sensitive inflammation marker. RBCa determination from erythrocyte sedimentation rate, ESR, is used since long, but is unspecific unless corrected for hematocrit, Ht. Whole blood viscosity measurement at low shear rate is also sensitive to RBCa but is cumbersome to apply. To investigate whether electrical blood impedance, being sensitive to spatial red cell distribution, can be a good alternative to determine RBCa in low shear conditions. Blood was collected from 7 healthy volunteers. From each 16 different samples were prepared with 4 different Ht.s and with 4 different fibrinogen concentrations. Viscosity was measured at low shear rate (4.04 s-1) with a rotational viscometer at 37.C. Electrical blood impedance was measured during similar shear conditions and temperature in a specially designed cuvette. ESR was determined according to Westergren. A logarithmic increase of viscosity as well as of capacitance, Cm, is seen when fibrinogen rises and an exponential increase when Ht rises. However, ESR shows a logarithmic decrease with increasing Ht and an exponential increase when fibrinogen rises. The viscosity could be accurately described using an exponential model. Under similar low shear conditions and temperature in-vitro, either whole blood viscosity or electrical blood capacitance reflect red blood cell aggregation due to fibrinogen and Ht variation in a similar way.

Cite this publication as follows:
Pop GAM, Hop WJ, Moraru L, vanderJagt M, Wuak J, Dekkers D, Chang Z, Gijsen FJ, Duncker DJ, Slager CJ: Blood Electrical Impedance Closely Matches Whole Blood Viscosity as Parameter of Hemorheology and Inflammation, Appl. Rheol. 13 (2003) 305.

Novel approach to rheological modelling of a fly ash-water mixture is proposed. The model is first tested against the available experimental data for a corn starch-water, a glass beads-water and a fly ash-water mixture and then used taking the advantage of available CFD code for a calculation of maJor and minor losses. Numerical results for Quadratic model are compared with results for Power law.

Cite this publication as follows:
Marn J, Ternik P: Use of Quadratic Model for Modelling of Fly Ash-Water Mixture, Appl. Rheol. 13 (2003) 286.

Cite this publication as follows:
Schweizer T: Influence of the molecular structure on the rheological properties of polystyrene and polycarbonate melts (Jens Hepperle), Appl. Rheol. 13 (2003) 284a.

This book covers extensively the topic of rotational spectroscopy of diatomic molecules which include closed shell systems as well as molecules with open shell electronic states. Starting with a general introduction into the field (Chap. 1), the main portion of the book (Chap. 2-7) is dedicated to theoretical descriptions, comprising the presentation of exact and effective Hamiltonians, angular momentum theory, fine and hyperfine structures, and other topics. The remainder of the book (Chap. 8-11) contains descriptions of various experimental techniques and results on diatomic molecules. In summary, this books gives a state-of-the-art description of most of the theoretical and experimental aspects concerned with rotational spectroscopy of diatomic molecules, not including however weakly bound diatomics such as rare gas dimers. Its high scientific standard recommends it for interested graduate students as well as for researchers in the field of molecular spectroscopy or related disciplines.

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Mä, der H: Rotational Spectroscopy of Diatomic Molecules (John Brown, Alan Carrington), Appl. Rheol. 13 (2003) 265.

Recently a new theory of viscosity of concentrated emulsions dependency on volume fraction of droplets (Starov V, Zhdanov G: J. Colloid Interface Sci, 258, 404 (2003)) has been suggested that relates the viscosity of concentrated emulsions to formation of clusters. Through experiments with milk at different concentrations of fat, cluster formation has been validated using optical microscopy and their properties determined using the mentioned theory. Viscometric studies have shown that within the shear rate range studied, both the packing density of fat droplets inside clusters and the relative viscosity of milk (viscosity over skim milk viscosity) are independent of shear-rate, but vary with volume fraction. Comparison of the experimental data with previous theories that assumed that the particles remained discrete shows wide variation. We attribute the discrepancy to cluster formation.

Cite this publication as follows:
Kyazze G, Starov V: Influence of Cluster Formation: Viscosity of Concentrated Emulsions, Appl. Rheol. 13 (2003) 259.

A general constitutive relation describing the change of viscoelastic behavior during the liquid - solid (sol - gel) transition which takes place in preceramic polymers is derived on the basis of Jeffrey.s 3-constants model with time dependent viscosities and elasticity. It is postulated that the sol - gel - transition can be analyzed analogous to the solutions of the Avrami equation used for modeling crystallization processes. Two different polymer systems used as precursor for the production of ceramic materials are investigated here: i) a mixture based on polysiloxane, alumatrane and isopropanol; ii) a non-oxidic carbodiimide gel based on the reaction of chlorosilanes with bis(trimethylsilyl)carbodiimide. Continuous measurements of the dynamic moduli versus reaction time, as well as creep tests at constant shear stress, evidenced both qualitative similarities and quantitative differences associated with the sol - gel transition of the two polymer systems. The shear rate and viscosity dependence of reaction time in creep tests, respectively the evolution of LissaJous figures associated with oscillatory experiments, are found to be consistent with the numerical simulations of the proposed constitutive relation.

Cite this publication as follows:
Balan C, Riedel R: Sol-Gel Modelling Associated with the Rheology of Polymeric Precursors of Ceramic Materials, Appl. Rheol. 13 (2003) 251.

Self-sensing is the technique of using a transducer to both actuate and sense concurrently, therefore eliminating the need for separate sensors. A sensorless rheometer could be much smaller, simpler and more robust than traditional designs. One application where such a rheometer would be desired is the in-situ measurement of curing bone cement in orthopaedic surgery. A set of equations was developed that models the relationship between force, motion and back-e.m.f. generation for a class of electromagnetic actuators. This enables velocity, displacement and force to be self-sensed from voltage measurements only. This self-sensing was validated on a conventional linear electromagnetic actuator, and a small rotary moving magnet device, which was designed to be a small self-sensing rheometer. The accuracy of the estimation was assessed and shown to compare favourably with measured data. The actuators were then used to construct simple rheometers to measure bone cement. Rheological models were used to calculate storage and loss moduli and dynamic viscosity from the self-sensed values of displacement, velocity and torque. The accuracy of these self-sensing rheometers was verified against a traditional rheometer using a silicone fluid and a polyethylene oxide solution. The self-sensing rheometers were used to characterise acrylic bone cements during curing, reinforcing and extending upon previous results. The elimination of sensors meant that it was possible to produce a small, inexpensive rheometer with a very simple structure. This indicates there is potential to develop small rheo-transducers for certain applications.

Cite this publication as follows:
Hanson B, Levesley M, Fisher J: Using Self-Sensing Techniques to Produce a Small, Robust, Inexpensive Rheometer, Appl. Rheol. 13 (2003) 242.

Cite this publication as follows:
Ruddle J: ACG First Minerals Processing and Tailings Rheology Workshop, Appl. Rheol. 13 (2003) 212.

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Hadjistamov D: The Yield Stress - A New Point of View. Letter to Editors., Appl. Rheol. 13 (2003) 209.

The intention of the paper is to illustrate the ability of the Brownian dynamics simulation technique applied to mesoscale polymer models in order to reproduce light scattering experiments of dilute polymer solution under flow. After suitable parameterization of a real polymeric system, polystyrene solved in a oligostyrene/toluene mixture at 299 K (good solvent conditions), a bead-spring model of the polymer chain is built and used to generate molecular traJectories on a computer. Such traJectories will capture the deformational and orientational processes experienced by the real polymer chain under flow. Then, from the set of molecular conformations generated, several polymer properties as well as typical scattering patterns can be reproduced quite accurately. FENE springs were used and excluded volume and non-preaveraging hydrodynamic interaction were taken into account in order to build a chain model as realistic as needed.

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HernandezCifre JG, delaTorre J: Radiation Scattering by Dilute Polymer Solutions in Shear Flow: An Example of Mesoscale Modeling and Brownian Dynamics Simulation, Appl. Rheol. 13 (2003) 200.

Rutting is a primary reason of premature deterioration of asphalt highway pavements. Pavements constructed with polymer and other modifiers are showing improved performance. The virgin asphalt and modified asphalt binders and mixes used on several test sections of the I-55 highway rehabilitation proJect in northern Mississippi are compared. The laboratory creep compliance data for these binders were measured at low temperatures using a modified test procedure adapted for the Bending Beam Rheometer device. Dynamic Shear Rheometer was used at high service temperatures. The creep compliance data of the binder was used as an input to simulate creep compliance behavior of the mix using a micromechanical model. The field evaluation confirms the relatively poor performance of the virgin asphalt section with respect to rutting, compared to modified binder sections.

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Uddin W: Viscoelastic Characterization of Polymer-Modified Asphalt Binders of Pavement Applications, Appl. Rheol. 13 (2003) 191.

Stagnation flow studies form a key research area in numerous applications dealt with industry. When a fluid approaches a solid boundary, it undergoes severe deceleration along the axis of impingement. We present the experimental findings of the effects of stagnation point on polymeric flow systems. While coating metal sheets or wires with a polymer melt, the metal sheet forms a moving plane on which a steady flow of the melt is maintained. Further in the process the polymer melt cools down and forms a coating. Stagnation region exists around the point where the polymer melt first touches the metal sheet. We try to simulate this situation except in our experiments the solid plane is not moving. The polymer solution flows down the inverted T-channel and strikes the base where we obtain the stagnation region. Laser Doppler technique is used to analyze the flow profile in this region. Initial analysis includes the analysis of a Newtonian fluid which is compared to theoretical predictions. Polyisobutadiene solution with three different concentrations, 0.1%, 1% and 3%, was tested for observing the effect of the change in concentration on the flow patterns around the stagnation point. In the stagnation region the fluid is not completely stagnant but follows a non-streamwise motion.

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Joshi K, Wedgewood L: Stagnation Flow Studies of Polymer Solutions in 2D System, Appl. Rheol. 13 (2003) 174.

In this paper, the linear and non-linear rheological properties of estuarine cohesive sediments were investigated. The density of the sediments has been determined by pycnometry. Creep and oscillatory shear measurements have been performed in order to determine i) the transitions in mechanical response to creep and oscillatory shear and ii) the material properties of these natural fluids as a function of their density. For all samples tested, four different rheological transitions have been determined and all material properties have been shown to be satisfactorily fitted by exponential functions of the density.

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Aubry T, Razafinimaro T, Jacinto RS, Bassoulet P: Rheological Properties of a Natural Estuarine Mud, Appl. Rheol. 13 (2003) 142.

A novel method to continuously measure the rate of build-up of an immobilised layer (apparent filter cake) was demonstrated for three mineral suspensions containing carboxymethyl cellulose and polymer latex. These suspensions were designed to be similar to those normally used as coating colours within the paper industry. The instrumentation was based on a rheometer equipped with units for controlling (and measuring) the normal forces acting on the rotating upper plate and precise measurements of the gap height in parallel.plate geometry. The bottom plate in the measurement cell was perforated and connected to vacuum, giving the driving pressure for flow through the filter. The technique should so far be taken as a qualitative, but is an attractive method for measuring filtration in thin films under controlled shear rate. The technique enables the apparent filter cake height to be calculated at any time during dewatering of the coating colours.

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Jä, der J, Jarnstrom L: The Influence of Thickener Addition on Filter Cake Formation During Dewatering of Mineral Suspensions, Appl. Rheol. 13 (2003) 125.

Polymer modified asphalt is an highly temperature sensitive material. To obtain the master curves of dynamic material functions, for this material, it is necessary to perform the testing over the temperature interval from - 30.C to at least 90.C. Since in this temperature range the polymer modified asphalt undergoes the transition from a glass-like to a Newtonian-like material, the benefit of using three testing geometries is studied here. The geometries used were: torsion bar (for the low temperatures), plate-plate (for the mid range temperatures) and bob and cup (for the high temperatures). The advantage of the combination of these three geometries is discussed. Stress and strain controlled rheometers were used to conduct all dynamic experiments. Master curves obtained by these geometries cover up to 20 decades of the reduced frequency.

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Polacco G, Vacin OJ, Biondi D, Stastna J, Zanzotto L: Dynamic Master Curves of Polymer Modified Asphalt from Three Different Geometries, Appl. Rheol. 13 (2003) 118.

The present work is concerned with the study of the rheology of polymer solutions spanning different concentration regimes and originates from a former round-robin research programme on this subJect, the S1 proJect, involving a number of research groups and institutions. The base fluid for this programme was the so-called S1 fluid, which is a 2.5% w/w solution of Polyisobutylene (PIB) in a solvent consisting of a mixture of polybutene oil and dekalin. In this paper a set of solutions having different concentrations of PIB are studied in steady shear, oscillatory shear and in axi-symmetrical contraction flows. The focus of the study is on the possibility of finding concentration scaling laws for polymer solutions spanning each or several of the concentration regimes. The results in shear flows show that it is possible to find scaling laws both for temperature and concentration in all regimes. Extensional results show that the curves superimpose within each concentration regime, but not over the whole range of concentrations. Accordingly, concentration scaling laws were then found for both shear and extension, the latter depending on the concentration regime: dilute, semi-dilute or concentrated.

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Nogueiro AJ, Maia JM: On the Influence of Concentration on the Rheology of Polymer Solutions:Can Scaling Laws Be Found?, Appl. Rheol. 13 (2003) 87.

The flow behaviour of colloidal dispersions is largely influenced by the interactions between the dispersed particles. We studied the influence of either natural or synthetic polyelectrolytes solutions on flow patterns within colloidal clay dispersion. For this purpose, highly diluted aqueous polymer solutions were intruded into a radial Hele-Shaw cell filled with montmorillonite dispersions. The developing flow patterns were recorded with a high resolution digital camera. The morphological parameters: fractal dimension, total number of branching, branching density of the patterns, compactness and form were obtained by digital image analysis. The results show that the patterns are largely affected by the different polymers.

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Beckmann S, Niemeyer J: Flow Patterns of Polymer Solutions Injected into Dispersions of Bentonite, Appl. Rheol. 13 (2003) 14.

The rheological behavior of model suspensions with the silicone oil M20000 and different concentrations of Cab-o-sil TS 720 resp. Durcal 5 are compared. The increase of the Cab-o-sil concentration changes the flow behavior of the suspension from shear-thinning, to pseudoplastic, and to plastic flow behavior. The first normal stress difference rises at the same time at certain shear rate. The disperse systems with Durcal 5 keep the structural viscous behavior of the silicone oil even with a filler concentration of 40.5 wt%. The dependence of the first normal stress difference on shear rate represents for suspensions with Durcal 5 only one straight line with a slope of n = 2. The normal stress has double the amount of the silicone oil M20000 at given shear rate and is independent of the used Durcal 5 concentration. It was established that suspensions with the silicone oil M20000 have a first normal stress difference that can, depending on the filler type, either increase (with Cab-o-sil TS 720) or decrease (with Durcal 5) at certain shear stress with increasing filler concentration. It is to be supposed that the decrease of the normal stress at a given shear stress, with increasing Durcal concentration, is a softening effect, caused by the filler.

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Hadjistamov D: Viscoelastic Behavior of Disperse Systems with Silicone Oil and Different Fillers, Appl. Rheol. 12 (2002) 297.

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Pearce MAD, Bellmer DD: Data Variability in Rheological Measurement of Semi-Solid Foods: Effects of Loading Normal Force, Appl. Rheol. 12 (2002) 282.

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Spevacek J, Ilavsky M: 4th International Conference on Polymer - Solvent Complexes and Intercalates , Appl. Rheol. 12 (2002) 260.

In the case of some highly viscous fluids, or thick pastes (such as those exhibiting high yield stress and/or high plastic viscosity), neither rotational nor tube type viscometers are suitable for rheological characterisation. Due to their capacity for generating and maintaining high torque or high rates of rotation, kneaders and mixers can often engender shear rates in excess of those of conventional rotational viscometers. Often these devices are instrumented, to measure and record the rate of rotation of the mixing blades and the related torque on the shaft turning the blades. The maJor problem facing users of these mixers lies in data interpretation, specifically in relating rate of rotation and torque data to shear rate and shear stress respectively. If it were possible to obtain such relationships, useful rheological data could be generated with instrumented mixers. This work outlines the experimental and analytical techniques required to convert pertinent data from the Ika Visc MKD 0.6-H60 instrumented kneader into useful rheological quantities. The kneader is calibrated using a Newtonian fluid and the calibration successfully tested with other Newtonian fluids, as well as on shear thinning solutions. The possibility of using a constant factor, a, which accounts for both the geometric complexity of the mixing chamber, and non-ideal fluid flow properties, is examined. It is shown that a is not constant, but depends on the non-Newtonian flow indices. At moderate and high rates of kneading blade rotation, calibration was not reliable and results are based on rates of rotation from 0 - 8rpm for the slower of the two mixing blades (0-16rpm for the quickly rotating blade). A number of assumptions and empirical relationships are utilised for this technique. The approximate nature of the technique necessitated by their use is more than offset by providing us with a potentially important outcome in that the capacity for collecting rheological data available to the interested scientist or engineer has been enhanced. A robust calibration technique has been developed, which is not, in principle limited to the specific equipment utilised for our analysis.

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Kealy T, Tiu C: Calibration of a Commercial Kneader for Rheological Applications, Appl. Rheol. 12 (2002) 241.

Bentonite are extensively used materials in a wide range of applications. Creep and oscillatory shear experiments in the linear viscoelastic domain were carried out on bentonite-water suspensions at different solid fractions. It was found that bentonite dispersions exhibit important viscoelastic behavior which could be represented by the generalized Kelvin-Voigt mechanical model. It is well known that an exhaustive study of colloidal dispersions may require the determination of its viscoelastic properties over a wide frequency scale. Unfortunately, due to microstructure changes, the experiments are limited in time. In order to avoid such limitation, oscillatory data were deduced from creep curves - without actually vibrating the clay dispersions - because a periodic experiment at frequency w is qualitatively equivalent to a creep test at time 1/w. That is, it was possible to complete the dynamic response in the low-frequency range using data obtained from the transient response in creep.

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Bekkour K, Kherfellah N: Linear Viscoelastic Behavior of Bentonite-Water Suspensions, Appl. Rheol. 12 (2002) 234.

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Vermant J: Physical Hydrodynamics (E. Guyon, J.P. Hulin, L. Petit, C.D. Mitescu), Appl. Rheol. 12 (2002) 172.

We examine the validity of the slump test for predicting the yield stress of polymeric suspensions and mineral suspensions. First we propose a modification of this test: in order to make measurements on fluids with high yield stress (of the order of several hundreds of Pascal) we add a mass at the sample top. From detailed observations of the slump in time we show that, for polymeric suspensions (hair gel and sewage sludges), two critical stresses can be distinguished which almost exactly correspond to the two critical stresses (respectively corresponding to a regime change and to the asymptotic slump) observed in rheometry during creep tests. Thus the slump test appears as a practiceful and relevant means to determine the intrinsic properties of these fluids. For mineral suspensions it is shown that the flow abruptly stops after a short time, a behaviour in agreement with the results of rheometrical tests carried out by progressively decreasing the applied stress. In that case the slump also appears to significantly depend on the procedure and cannot be related to a single property of the material.

Cite this publication as follows:
Baudez J-C, Chabot F, Coussot P: Rheological Interpretation of the Slump test, Appl. Rheol. 12 (2002) 133.

A frequent problem in the production of metallocene linear low-density polyethylene (mLLDPE) films is the occurrence of flow instabilities, e.g. sharkskin, or degradation of material, which limit the production rate and decrease the product quality. If such problems arise, the question is what causes these phenomena and how they can be avoided. With the aim of understanding these problems and providing some guidelines for their suppression, rheological measurements together with modelling of these melt flows are often employed. In the present study, flow behaviour of two commercially available mLLDPEs was determined and used for the process simulation. The paper shows that the capillary-rheology data together with 2D finite element method can be used for the prediction of sharkskin phenomenon as well as degradation of mLLDPE melts in film blowing dies. It also reveals that the degradation of the materials in these dies can be quantified through wall shear stress. Finally, the paper describes how these findings can help optimize the flow channel in the film blowing die to avoid the undesirable flow phenomena.

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Zatloukal M, Vlcek J, Slanik A, Lengalova A, Simonik J: Experimental and numerical investigation into metallocene polymer melt flow in film blowing dies, Appl. Rheol. 12 (2002) 126.

The obJective of this study is mainly to review recent work concerning the numerical modeling of the stick-slip and gross melt fracture polymer extrusion instabilities. Three different mechanisms of instability are discussed: (a) combination of nonlinear slip with compressibility; (b) combination of nonlinear slip with elasticity; and (c) constitutive instabilities. Furthermore, preliminary numerical simulations of the time-dependent, compressible extrudate-swell flow of a Carreau fluid with slip at the wall, using a realistic macroscopic slip equation that is based on experimental data for a high-density polyethylene, are presented.

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Achilleos E, Georgiou GC, Hatzikiriakos SG: On numerical simulation of polymer extrusion instabilities, Appl. Rheol. 12 (2002) 88.

The vane geometry with a large gap is used to determine the Newtonian, non-Newtonian and viscoelastic properties of complex fluids. We show that when this geometry is carefully characterized, it can be used for precise rheometry. A novel effective cylinder approximation is used to obtain the shear rate and shear stress factors. The effective radius is found to be close to the height of the triangle formed by Joining the tips of adJacent blades. This result differs significantly from that of previous work. Flow visualization has been used to confirm that the stream lines bend towards the centre between the blades. These factors can be used to determine the flow curves of non-Newtonian liquids, using Krieger.s power law expansion. The standard procedure for using the vane to determine the yield stress is also carefully investigated and alternative procedures are suggested.

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Baravian C, Lalante A, Parker A: Vane rheometry with a large, finite gap, Appl. Rheol. 12 (2002) 81.

The temperature dependent flow properties of highly filled polymer compounds intended for production of hard-metal parts by powder inJection moulding (PIM) technology were studied. The pure binder based on polyethylene, ethylene and butyl acrylate block copolymer and paraffin, and its compounds with hard-metal carbide powder (up to 55 vol. %) were prepared by melt mixing at 180.C. The flow properties were investigated at the temperature range from 140.C to 200.C using capillary rheometer operating flow at a constant piston speed. The measure of temperature sensitivity of PIM compounds, activation energy of shear flow, decreases with powder loading and shear rate. The Arrhenius relation for these materials is only valid in the stable flow region. At the temperatures above 170.C the compounds filled with 45 vol. % carbide powder and higher exhibit an unstable flow of pressure oscillations type at the shear rates above 103 s-1. The onset of pressure oscillations is strongly affected by temperature. The relation between critical shear stress for the onset of pressure oscillations and temperature is non-linear.

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Honek T, Hausnerova B, Saha P: Temperature dependent flow properties of powder injection moulding compounds, Appl. Rheol. 12 (2002) 72.

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Rheological Societies, Bouton J, Guerrero A, Young NWG: The Society's Site Mar 2002 - Aug 2002 , Appl. Rheol. 12 (2002) 45.

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Mavrantzas VG, Tsamopoulos J: The 3rd International Conference of the Hellenic Society of Rheology (HSR), Appl. Rheol. 12 (2002) 35.

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Eischen JC, Windhab EJ: Viscosity of Cocoa and Chocolate Products, Appl. Rheol. 12 (2002) 32.

The viscoelastic properties of a magneto-rheological fluid can be variably controlled using a magnetic field. A new measuring method is introduced which is based on oscillatory tests. In contrast to flow curves from experiments at steady shear rate, the new method allows an exact determination of a magneto-rheological fluid.s viscoelastic properties as a function of the preset magnetic field strength. The .Magneto Sweep. is an oscillatory test method, each with constant amplitude and constant frequency while logarithmically increasing the magnetic field strength (Magneto Sweep). For typical magneto-rheological fluids (MRF) three characteristic regions and two significant transition points can be determined. These transitions mark the corresponding change in material behavior resulting from an increasing magnetic field strength.

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Wollny K, Lä, uger J, Huck S: Magneto Sweep - A Method for characterizing the Viscoelastic Properties of Magneto-Rheological Fluids, Appl. Rheol. 12 (2002) 25.

Due to a number of practical difficulties, both in- and on-line measurements of the rheological properties of complex systems during extrusion are usually performed at the end of the extruder, under very specific experimental conditions. This makes this type of instruments more useful for quality control than for process optimisation, since information about the influence of the geometry and/or processing conditions on the evolution of the material characteristics inside the extruder is not easily gathered. Recently, however, the authors have developed an on-line capillary rheometry system that overcomes most of the existing problems and allows small amounts of sample to be tested in very near real time, along the extruder. The present work aims at illustrating the usefulness of this concept for the study of physical compounding processes and some reactive systems. Two very different systems will be used for that purpose: a reactive extrusion process (the peroxide-induced thermal degradation of polypropylene) and the dispersive mixing involved in the preparation of thermoplastic/carbon fibre composites.

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Maia JM, Carneiro OS, Machado AV, Covas JA: On-Line Rheometry for Twin-Screw Extrusion (Along the Extruder) and its Applications, Appl. Rheol. 12 (2002) 18.

The grouts are suspensions containing cement used in the technique of prestressing by post-tension. Cement, from its chemical nature, protects the wire ropes (strands) from corrosion. To be able to play correctly this protective role, the grout must remain homogeneous and must entirely cover the strands. The lack of stability of the grouts, which results in packing or sedimentation, is a maJor problem. In this article, we try to correlate the rheological properties of the grout with its capacity to remain homogeneous. We show that an increase in the concentration of superplasticizer, a polymer solution, decreases the thixotropic behavior of the grout, but on the other hand, increases the effects of sedimentation. We explain this phenomenon by the modification of the structure of a three-dimensional network in relation to the interparticle interactions.

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LeRoy R, Boucenna I, Flaud P: Stability of Cement Grout: Study of Sedimentation Phenomena, Appl. Rheol. 12 (2002) 12.

Suitability of finite difference method and finite volume method for computation of incompressible non newtonian flow is analyzed. In addition, accuracy of numerical results depending of mesh size is assessed. Both methods are tested for driven cavity and compared to each other, to results from available literature and to results obtained using commercial code CFX 4.3.

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Marn J, Delic M, Zunic Z: Non-Newtonian Fluid Flow Analysis with Finite Difference and Finite Volume Numerical Models, Appl. Rheol. 11 (2001) 325.

A method has been proposed for quantitative characterization of the flow behaviour of fluids, which is an important problem of applied rheology. Particle Image Velocimetry technique has been used for visualization and measurement of the velocity field. The rheometric study of the fluid is aimed at determining the character of the flow and its dynamic viscosity. It is shown that the experimental data obtained for the velocity field and the viscosity are necessary and sufficient for determining the shear stress field at each point of the flow bulk. The maJor part of the investigations are performed using a Newtonian fluid (epoxy resin), but some data for the non- Newtonian fluid (solution of xantan) are shown too. The flow is produced by gravity in a system of tubes (a barrel and a capillary) with different round crossections. The possibility of further improvement of the combined rheo-optical method is shown.

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Ivanov Y, Kavardjikov V, Pashkuleva D: Combined Method for Quantitative Characterisation of Fluid Flow, Appl. Rheol. 11 (2001) 320.

The viscoelasticity of reduced-fat Cheddar and Mozzarella cheeses was characterized in small (parallel disk rheometer, go = 0.01) and large (sliding plate rheometer, 0.2< go <7) amplitude oscillatory shear at 40 and 60 C. We deduced the linear relaxation spectrum from the small strain measurements. At large strain amplitudes, we found sinusoidal stress responses whose amplitudes are well below those predicted from the linear relaxation spectrum, and yet remarkably linear with strain amplitude. We call this the large strain linear regime. We discovered that the Lodge rubberlike liquid can quantitatively explain the large strain linear regime if we scale down the relaxation moduli in the linear spectrum by a constant. This large strain linear regime persists to much higher strain amplitudes for Cheddar (go <= 4) than for Mozzarella (go <= 1). This is perhaps due to oriented structure of the protein matrix in the Mozzarella cheese.

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Wand YC, Gunasekaran S, Giacomin AJ: The Lodge Rubberlike Liquid Behavior for Cheese in Large Amplitude Oscillatory Shear, Appl. Rheol. 11 (2001) 312.

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Maia JM: Numerical and analytical methods in non-Newtonian fluid mechanics, Appl. Rheol. 11 (2001) 287.

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Lä, uger J, Raffer G: Physica advanced Peltier system PTD150 (Pat. Pendt.). Making the temperature control with a Peltier system accurate, Appl. Rheol. 11 (2001) 281.

In this work, it is attempted to theoretically understand the phenomenon of wall slip through empirical and molecular models. Initially, we use the framework a transient network theory. We show that the severe disentanglement in the interfacial region can give rise to non-monotonic flow curve locally in that region. Further, we generalize this model into a unified slip model, which predicts wall slip by either disentanglement or by debonding mechanism, depending upon the adhesive energy of the wall-polymer pair. The model predictions of the critical wall shear stress are in good agreement with experiments for various adhesive energies of the wall-polymer pair. The model predicts that the temperature dependence of the critical wall shear stress for debonding is different than that of disentanglement mechanism under certain experimental conditions. To validate the predictions of unified model, we measure the critical stress for sudden slip due to debonding for various temperatures using cone and plate viscometer with fluoroelastomer-coated cone. The temperature dependence of the critical stress for instability (slip) on a coated cone is found out to be inversely dependent on temperature, which expected for the case of debonding. In the final part of this thesis, we develop a parameter-free tube model for predicting the stick-slip phenomenon. The model, which is based on the contour variable model [Mead et al., 1998, Macromolecules, 31, 7895], considers the dynamics of the tethered chains, which are grafted on a highenergy wall and which are entangled with the bulk chains flowing past them. We show that the restricted relaxation modes of the tethered molecule give rise to discontinuous slip instability. More specifically, the slow relaxation of the tethered chain due to the restricted convective constraint release is unable to randomize its flow-induced orientation above a critical shear rate or stress. This decreases the resistance to flow for the bulk chains, which suddenly slip past the oriented tethered chains.

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Joshi YM: Studies on Wall-Slip in Entangled Polymeric Liquids, Appl. Rheol. 11 (2001) 277.

To overcome difficulties (slip, sample disturbance) associated with traditional sensors, a semi-empirical method was developed to allow the use of a 4-bladed vane sensor in small strain oscillatory testing. It was assumed that the vane sensor acted as a bob with an acting radius, RV, different from the actual radius of the vane (0.02005 m). To solve for RV, the complex modulus obtained using a concentric cylinder sensor from reference viscoelastic fluid, was set equal to the complex modulus equation for vane sensor. RV values were grouped into three phase shift ranges from 5° to less than 16°, from 16° to less than 60°, and from 60° to 90° and they were 0.01883, 0.01869, and 0.01850 m, respectively. These values were used in the calculation of viscoelastic properties of eight commercial food products, which resulted in complex modulus values within 15% of those obtained using a concentric cylinder sensor. Results showed that this particular vane and cup system can be used to directly measure the storage and loss moduli of viscoelastic material and phase shift within the upper frequency value of 6.28 rad/s. Above 6.28 rad/s, there is an inconsistency in phase shift angles measured using vane method. This method is ideal for testing thixotropic food systems because disturbance is minimal during sample loading, giving more accurate viscoelastic measurements.

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Junus S, Briggs JL: Vane sensor system in small strain oscillatory testing, Appl. Rheol. 11 (2001) 264.

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Fischer P: Mechanical Response of Polymers - An Introduction (Alan S.Wineman, K. R. Rajagopal), Appl. Rheol. 11 (2001) 257.

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Masubuchi Y, Morii T, Saito T, Ito H, Nonomura C: Applied Rheology discussed in the 12th Annual Meeting of the Japan Society of Polymer Processing (JSPP), Appl. Rheol. 11 (2001) 230.

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Laitinen J, Rowe GM: First European Symposium on Bituminous Materials Rheology and Pavement Performance, Appl. Rheol. 11 (2001) 228.

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Becker GW: Festvortrag 50 Jahre Deutsche Rheologische Gesellschaft , Appl. Rheol. 11 (2001) 210.

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Fischer P, Kroger M: Golden Jubilee meeting of the German Society of Rheology, Appl. Rheol. 11 (2001) 207.

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Isaakide G, Frendel A, Bouton J: Product Info: MiniLab - Compounder and Reactor, Appl. Rheol. 11 (2001) 203.

The crosslinking reaction in various types of polymer blends was followed by rheological measurements. Miscible polymers with controlled glass transition temperature, chain length and number of functional units per chain were synthesized by bulk radical copolymerization. Other experiments were carried out on immiscible systems based on commercial polymers. Blends were either prepared in a batch mixer or directly in the parallel-plate geometry of a rotational rheometer. Due to the low glass transition or melting temperature of most blend components, it was usually possible to separate the mixing step which was carried out at low temperature from the crosslinking reaction which was followed by small amplitude dynamic measurements at higher temperatures. The influence of several parameters on the reaction was studied, in particular : the reaction temperature, the amount of shear during the mixing step (or mixing time), the number of functional units per chain in each blend component and the blend composition. For the miscible blends, a master curve for the dependence of the elastic modulus G as a function of reaction time could be drawn for different functionalities and blend compositions.

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Muller R, Bouquey M, Mauguiere F, Schlatter G, Serra C, Terrisse J: Rheology of reactive polymer blends: separation of mixing and reaction steps, Appl. Rheol. 11 (2001) 141.

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Laun HM: Laudatio: Professor Dr. Joachim Meissner, named Honorary Member of the German Society of Rheology, Appl. Rheol. 11 (2001) 102.

This study is attempted to demonstrate the application of rheological measurements in characterization of cosmetics products. As part of this study, several rheological tests were carried out on three common, commercially available body lotions to analyze their complex properties. The tests described in this study were simple and predictive in which the viscoelastic properties were successfully related with the end-use performance properties such as applicability, processing behavior, temperature sensitivity and storage and thermal stability.

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Yao ML: Rheological characterization of body lotions, Appl. Rheol. 11 (2001) 83.

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Bouton J, Ait-Kadi A: The 50th canadian society of chemical engineering conference, Appl. Rheol. 11 (2001) 40.

The different methods that can be used for measuring the effect of a hydrostatic pressure on the viscosity of polymer melts are evaluated. A linear low-density polyethylene is chosen as test material, as it can be expected to have a small pressure dependency. Special attention is given to methods employing capillary rheometry, as these methods yield a range of shear rates and pressures that are typically encountered under polymer processing conditions. The accuracy of the different techniques is evaluated considering also the complexity of the experimental devices. First it is investigated to which extent standard capillary rheometry can be used to extract information about the pressure dependency of the viscosity. Secondly, it is shown how the accuracy can be greatly increased by the simple addition of a pressure chamber below the exit of the capillary, with a needle valve to regulate the back pressure. The results from this device are compared with those from a more robust method using a pressurized double piston rheometer and with literature data. The experimental values for the pressure coefficient of the viscosity will also be compared with those predicted from PVT data using Utracki's method.

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Goubert A, Vermant J, Moldenaers P, Gö, ttfert A, Ernst B: Comparison of measurement techniques for evaluating the pressure dependence of the viscosity, Appl. Rheol. 11 (2001) 26.

Laboratory-scale experiments were carried out to explore the influence of the composition of the fat phase on mechanical and rheological properties of processed model cheeses. Cheeses made from caseinates, emulsifying salts and a milk fat fraction liquid at 24°C, which was achieved by thermal separation, showed much lower moduli than processed model cheeses manufactured with a fat fraction solid at 30°C. Processed model cheeses made from caseinates, emulsifying salts and a hard butter with a low amount of unsaturated fatty acids were significantly higher in firmness than cheeses made with soft butter with a higher amount of unsaturated fatty acids. In experiments using mature Gruyè and emulsifying salts, processed cheeses made from summer Gruyè were less firm than processed winter Gruyè. The results indicate that fat composition strongly affects mechanical properties of processed cheese, and a model is provided to explain structural changes during deformation.

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Jaros D, Petrag J, Rohm H, Ulberth F: Milk fat composition affects mechanical and rheological properties of processed cheese, Appl. Rheol. 11 (2001) 19.

The melt rheology of a low Tg tin phosphate glass [Pglass] has been studied with oscillatory shear flow experiments to accelerate efforts to melt process the glass with different organic polymers. The w dependence of the complex viscosity h* of the Pglass is easily predicted by a modified Rouse model with two relaxation times. The complex viscosity of the glass at different temperatures and frequencies can be superposed and described by the Arrhenius equation. At higher temperatures, the melt viscosity of the Pglass increased monotonically with time. This viscosity rise is thought to be due to sample crystallization. The Pglass was melt-mixed with two different thermoplastic polymers (low-density polyethylene and polystyrene) to produce unique hybrid materials with interesting microstructures.

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Adalja SB, Otaigbe JU: Melt rheology of tin phosphate glasses, Appl. Rheol. 11 (2001) 10.

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Pannetier N, Habas J-P, Francois J: A comparative rheological study of lime/molasses and, Appl. Rheol. 10 (2000) 238.

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Schweizer T: Rheology for Polymer Melt Processing (J. M.-Piau, J.-F. Agassant, Eds.), Appl. Rheol. 10 (2000) 222.

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Zanzotto L, Stastna J, Vacin OJ: Thermomechanical properties of several polymer modified asphalts, Appl. Rheol. 10 (2000) 185.

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Resch JJ, Daubert CR: A Recap of Rheological Analysis of Foods: Theory and Practice, Appl. Rheol. 10 (2000) 146.

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Gleissle W: 3rd ESAFORM Conference on Material Forming, Appl. Rheol. 10 (2000) 145.

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Windhab EJ: Fluid immobilization - a structure-related key mechanism for the viscous flow behavior of concentrated suspension systems, Appl. Rheol. 10 (2000) 134.

Distributive fluid mixing in laminar flows is studied using the concept of concentration distribution mapping matrices, which is based on the original ideas of Spencer & Wiley [1], describing the evolution of the composition of two fluids of identical viscosity with no interfacial tension. The flow domain is divided into cells, and large-scale variations in composition are tracked by following the cell-average concentrations of one fluid using the mapping method of KruiJt et al. [2]. An overview of recent results is presented here where prototype two- and three-dimensional timeperiodic mixing flows are considered. Efficiency of different mixing protocols are compared and for a particular example the (possible) influence of fluid rheology on mixing is studied. Moreover, an extension of the current method including the microstructure of the mixture is illustrated. Although here the method is illustrated making use of these simple flows, more practical, industrial mixers like twin screw extruders can be studied using the same approach.

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Anderson PD, Meijer HEH: Chaotic mixing analyses by distribution matrices, Appl. Rheol. 10 (2000) 119.

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Hetzel F, Nielsen J, Wiesner S, Brummer R: Dynamic mechanical freezing points of cosmetic O/W emulsions and their stability at low temperatures, Appl. Rheol. 10 (2000) 114.

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Kroger M, Vermant J: The structure and rheology of complex fluids (R.G. Larson), Appl. Rheol. 10 (2000) 110.

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Afonso IM, Maia JM: Rheological Monitoring of Structure Development and Rebodying of Set-Style Yoghurt, Appl. Rheol. 10 (2000) 73.

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Flaud P, Bouton J: 34th annual general meeting of the french group of rheology (GFR), Appl. Rheol. 10 (2000) 38.

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Hugelshofer D, Windhab EJ, Wang J: Rheological and Structural Changes During The Mixing of Suspensions and Emulsions, Appl. Rheol. 10 (2000) 22.

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Carlson ED, Lai J: 71st annual meeting of the society of rheology , Appl. Rheol. 9 (1999) 268.

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Banerjee R, Puniyan RR: Effect of Eucalyptus Oil Added Surfactants on the Rheology of Mucus Gel Simulants, Appl. Rheol. 9 (1999) 254.

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Arikainen EO, Earnshaw JC, Wehling A, Waghorne E: A Rheo-Optical Investigation into the Viscoelastic Moduli of Acidified Milk Gel, Appl. Rheol. 9 (1999) 246.

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Hadjistamov D: Dilatant Behavior of Systems with the Thixotropic Agent Aerosil 380 in the, Appl. Rheol. 9 (1999) 212.

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Friedrich C, Leblanc JL: MENUSIM workshop. Measuring the rheological properties of polymeric materials, Appl. Rheol. 9 (1999) 219.

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Weigand J: Viscosity Measurements on Powders with a new Viscometer, Appl. Rheol. 9 (1999) 204.

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Thimm W, Friedrich C, Maier D, Marth M, Honerkamp J: Determination of Molecular Weight Distributions from Rheological Data: An, Appl. Rheol. 9 (1999) 150.

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Berret J-F: Rheology, rheo-physics and flow-induced structures of liquid crystalline polymers, surfactants and block copolymers, Appl. Rheol. 9 (1999) 126.

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Nakajima N: Academic Rheology and Industrial Rheology - A Personal Reflection, Appl. Rheol. 9 (1999) 116.

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Cirman C, Bouquey M, Terrisse J, Muller R: Rheological Study of the Interfacial Crosslinking Reaction in Reactive, Appl. Rheol. 9 (1999) 108.

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Vermant J, Brown ADB, Kroger M: Time resolved evolution of soft condensed matter under flow, Appl. Rheol. 9 (1999) 38.

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Braithwaite GJC, McKinley GH: Microrheometry for Studying the Rheology and Dynamics of Polymers near, Appl. Rheol. 9 (1999) 27.

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Sievering C, Schneider FH: Significance of Agar/Water/Sugar Suspension Flow Properties during Production of Jellies, Appl. Rheol. 7 (1997) 248.

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Madiedo JM, Gallegos C: Relaxation and Retardation Spectra of Concentrated Emulsions, Appl. Rheol. 7 (1997) 161.

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Schieber J, Fischer P, Kroger M: New aspects in polymer rheology, Appl. Rheol. 7 (1997) 123.

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Hanselmann W, Windhab EJ: Foam Flow in Pipes, Appl. Rheol. 6 (1996) 253.

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Hadjistamov D: Dependance of the First Normal Stress Difference of Silicone Oils on Zero-Shear Viscosity and Molecular Weight, Appl. Rheol. 6 (1996) 203.

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Halley PJ: Chemorheology of Highly Filled Epoxy Molding Compounds, Appl. Rheol. 6 (1996) 106.

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Dongré, R, Youtchef J, Anderson D: Better Roads Through Rheology, Appl. Rheol. 6 (1996) 75.

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Wolf B, Windhab EJ: Interfacial Rheology of Deformable Droplets in Viscometric Flows, Appl. Rheol. 5 (1995) 182.

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Wunderlich J, Lohmann T: Inertial Effects in Oscillatory Experiments with a Coaxial Cylinder Rheometer, Appl. Rheol. 5 (1995) 134.

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Meissner J: Polymer Melt Elongation, Appl. Rheol. 5 (1995) 120.

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Hadjistamov D: Relationship between the Normal Stress Difference and the Shear Stress, Appl. Rheol. 5 (1995) 29.

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Breton Vea, Korolczuk J, Doublier JH, Maingonnat JF: Rheological Properties of Maize Starch Pastes and Gels, Appl. Rheol. 5 (1995) 24.

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Janocha H, Rech B: Measurements of MR-Fluids using Rotational Viscometers, Appl. Rheol. 4 (1994) 198.

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Abu-Jdayil B, Brunn PO: Optical Measurements of the Velocity Profile of ER-Fluid in a Rectangular Conduit, Appl. Rheol. 4 (1994) 186.

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Jaros D, Rohm H: Uniaxiale Compression of Cheese at Constant Strain Rate, Appl. Rheol. 4 (1994) 77.

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Weese J, Friedrich C: Relaxation time spectra in rheology: Calculation and examples, Appl. Rheol. 4 (1994) 69.

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Hadjistamov D, Gutekunst F: Capabilities and Limits of the Press Flow Method, Appl. Rheol. 4 (1994) 29.

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Schmidt M, Franck AJ: Comments on the Application of Stress Controlled and Strain Controlled Rheometers, Appl. Rheol. 4 (1994) 23.

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Osterhold M, Jä, ger Y: Rheological Characterization of Powder Coatings, Appl. Rheol. 3 (1993) 250.

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Westkä, mper E, Meschke J: Study of the Flow Behavior of Electrorheological Fluids (ERFs) and their Use in Passive Absorber, Appl. Rheol. 3 (1993) 243.

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Marquardt W, Nijmann J: Experimental Errors when Using Rotational Rheometers, Appl. Rheol. 3 (1993) 120.

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Hadjistamov D: Viscoelastic Properties of Filled Silicone Fluids, Appl. Rheol. 3 (1993) 113.

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Janocha H, Rech B: Measurements on Electroreological Liquids with Rotational Viscometers, Appl. Rheol. 3 (1993) 39.

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Graczyk J, Gleissle W: Rheologie and Extrudability of Ceramic Componounds, Appl. Rheol. 3 (1993) 28.

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Brunn PO, Vorwerk J, Steger R: Optical and Acoustic Rheometers: Three Examples, Appl. Rheol. 3 (1993) 20.

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Reilly JF: A Practical Method for Correlating Melt Rheology of PET to IV (Intrinsic Viscosity), Appl. Rheol. 2 (1992) 174.

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Schurz J: Empirical Flow Curve Interpretation of Polyethylene Oxide Solutions, Appl. Rheol. 2 (1992) 166.

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Windhab EJ: Behaviour of Shear-Induced Structures in Multi-Phase Systems, Appl. Rheol. 2 (1992) 102.

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Adler HJ: Rheological Investigations into Water-Thinnable Paints Binders, Appl. Rheol. 2 (1992) 96.

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Schrö, der J: Some Comments on the Flow Properties of Pigment Dispersions, Appl. Rheol. 2 (1992) 40.

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KlarskovKristiansen M, Jakobson J, Saarnak A: Verification of the Orchard Levelling Analysis, Appl. Rheol. 2 (1992) 30.

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Schulze K, Raeuber H-J, Guthy K: Viscoelastic Properties of Milk During Yogurt Fermentation, Appl. Rheol. 1 (1991) 160.

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Franck AJ: DMT of polymers, Appl. Rheol. 1 (1991) 84.

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Franck AJ, Gerth C, Giesekus H, TSas HE: Focus on Rheology!, Appl. Rheol. 1 (1991) 40.

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Windhab EJ, Wolf B: Investigation of the Rheological Behaviour of Small Droplets in Emulsions, Appl. Rheol. 1 (1991) 17.