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Gui Wang, Hui DuAuthor index ►
Rheological Properties of Kcl/Polymer Type Drilling Fluids Containing Particulate Loss PRe.Ention Material
Appl. Rheol. 28:3 (2018) 35727 (6 pages) ►
Rheological properties of KCl/polymer type drilling fluids containing particulate loss pRe.Ention material (LPM) were characterized by an integrated inverse model-experimental approach. Rheological measuRe.Ents for LPM-laden KCl/polymer type drilling fluids were carried out on a 6-speed rotational viscometer. The algorithm based on Tikhonov regularization was validated to be applicable and reliable to compute the shear rate in a rotational viscometer equipped with a widened annular gap. With the validated algorithm, the dial readings versus rotational speed data were transformed into shear stress vs. shear rate form. The results indicate that the rheological diagrams of the KCl/polymer type drilling fluids Re.Emble those of a yield stress fluid and can be well repRe.Ented by the Hershel-Bulkley model. The observed variation shows that rheological parameters were affected significantly by the addition of particulate LPM. The amount and the particle size of particulate LPM have a combined effect on the rheological properties of LPM-laden KCl/polymer type drilling fluids.► Cite this publication as follows:
Wang G, Du H: Rheological Properties of Kcl/Polymer Type Drilling Fluids Containing Particulate Loss Prevention Material, Appl. Rheol. 28 (2018) 35727.
In this paper, we pRe.Ent a novel method we have developed for measuring the drag reduction in a dilute polymer solution, based on the triboelectricity phenomenon. The pRe.Ence of a small quantity of polymer with high molecular density in a liquid decreases the friction of the liquid on solid walls. This property defines drag reduction. The friction itself produces electricity in the liquid known as triboelectricity. In this work, we show that drag reduction can be measured by measuring the triboelectric voltage in the solvent and in the polymer solution. The method was tested on well characterized dilute solution of polyethylene oxide (PEO) and the results obtained agree qualitatively well with those available in the literature, notably showing that for given flow rate, drag reduction by PEO increases with polymer concentration until reaching a plateau. Also, for given concentration, drag reduction increases with flow rate in the range of concentration and flow rate tested. More generally, a similar behavior is expected for any polymer solution obeying the power-law rheological model.► Cite this publication as follows:
Nsom B, Latrache N: Measurement of Drag Reduction in Dilute Polymer Solution using Triboelectric Effect, Appl. Rheol. 28 (2018) 25922.
The time dependent rheological behavior of a concentrated CaCO3 particle suspension is studied. The particles are suspended in a mixture of three industrial products: two resins, composed of styRe.E monomer, a styRe.E-butadiene-styRe.E block copolymer, and an unsaturated polyester oligomer, and one surfactant, acting as a dispersing agent for the particles. For the measuRe.Ents, a MCR 301 rheometer from Anton Paar is used in the rotational mode, with a Couette geometry. An unusual behavior is observed, in which the low shear-rate viscosity of the suspension depends in a non-monotonous way on the shear rate applied during a previous shear history. The viscosity of the suspension at low shear rate depends both on the value of the prior shear rate, and the time during which it is applied. We found that the phenomenon is more pronounced when the particles volume fraction is increased. We propose an interpretation of the observed phenomenon in which links of different strengths can be formed between the particles and only the weakest links are destroyed by moderate shear rates.► Cite this publication as follows:
Rothan A, Muller R, Hebraud P, Castro M, Bouquey M, Serra C: Unusual time dependent rheological behavior of a concentrated suspension, Appl. Rheol. 27 (2017) 64182.
Visco-plasticity characterized by yield stress is an important rheological property of composite propellant suspensions. The yield stress along with viscosity affects various unit operations in propellant processing as well as the quality of final product. The characterization of yield stress of propellant suspensions using direct measuRe.Ent techniques, such as forced falling ball and slump test is described. The slump test is a simple and quick measuRe.Ent tool with applicability at processing site whereas forced ball drop is useful for measuRe.Ent of very high yield stress. The yield stress measuRe.Ent of propellant suspension of four different compositions with varying particle size and volume fraction using above methods is reported and results are compared with vane geometry of rotational rheometer. Further, the yield stress behavior was studied for the propellant compositions with increasing solid loading. The dependence of yield stress of the studied propellant compositions on the reduced packing fraction φ/φm of solids is established and expressed by a mathematical correlation. In addition, effect of vibration on yield stress was also studied using slump test.► Cite this publication as follows:
Dombe G, Yadav N, Lagade R, Mehilal M, Bhongale C: Studies on Measurement of Yield Stress of Propellant Suspensions using Falling Ball and Slump Test, Appl. Rheol. 27 (2017) 45262.
Rheological properties and the mechanical relaxation behavior of rubbery amorphous sucrose-maltodextrin-sodium citrate systems were studied at room temperature using the small amplitude oscillatory shear test in the frequency range of 0.1 - 150 Hz. The system with high sucrose concentration exhibited viscous-dominant relaxation, while the system with high maltodextrin concentration exhibited elastic-dominant relaxation. The addition of sodium citrate could retard molecular mobility presumably due to its molecular interaction with sucrose rather than with maltodextrin. The technique was capable to detect changes in molecular process even with a small variation in the matrix components. Evidences obtained with scanning electron micrographs suggested the possible effect of sodium citrate to interfere with molecular interactions in the system with high maltodextrin concentration, i.e. the system tended to be more brittle.► Cite this publication as follows:
Sritham E, Gunasekaran S: Rheological and Microstructure Evaluations of Amorphous Sucrose-Maltodextrin-Sodium Citrate Mixture, Appl. Rheol. 27 (2017) 43102.
Limited information exists in literature regarding the effect of styRe.E-butadiene rubber (SBR) latexes on rheology and stability of lightweight self-consolidating concRe.E (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 concRe.E 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.
► Cite this publication as follows:
Handge UA: Geesthacht Polymer Days: 'Rheology of Polymers for Research and Application', Appl. Rheol. 27 (2017) 47.
The addition of certain ingredients in conventional concRe.E is essential for improving rheological properties of this construction material. The effect of limestone and superplasticisers on the hydration kinetics of self-compacting concRe.E (SCC) was investigated on cement paste scale. These additives interact mostly with cement paste, since aggregates are considered to be inert materials. The understanding of the effect of these mineral and chemical additives on the hydration kinetics of cement paste is the key to design a self-compacting concRe.E with great properties. Four CEM I 52.5 N Portland Cements, limestone (LS) and one type of superplasticiser (SP) were used in this Re.Earch. The hydration kinetics weRe.Evaluated by monitoring the storage modulus growth and different coefficients of a self-acceleration kinetics equation were used to depict the effect of different concentrations of SP with and without the optimum concentration of limestone (30 %) on the hydration kinetics of cement pastes. It was observed that the rate of hydration increased with the increase in SP concentration depending on the cement used. The addition of limestone in the superplasticised cement paste significantly retarded the hydration kinetics for all four cements. The rheological behavior of self-compacting cement paste was found to be very sensitive to the chemical and physical properties of the cements used.► Cite this publication as follows:
Elmakki R, Masalova I, Haldenwang R, Malkin A, Mbasha W: Effect of limestone on the cement paste hydration in the presence of polycarboxylate superplasticiser, Appl. Rheol. 26 (2016) 25122.
A Sentmanat Extension Rheometer repRe.Ents one out of a few experimental devices for the measuRe.Ent 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 pRe.Ented visualization technique is demonstrated using branched LDPE EscoRe.E. 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.
The knowledge of enzymatic activity is necessary in many industrial processes. The common measuRe.Ent techniques are time-consuming and therefore cost-intensive. MeasuRe.Ents 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 measuRe.Ents 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 requiRe.Ents. A correlation model based on the Martin equation and necessary assumptions are pRe.Ented. The required parameters intrinsic viscosity and Martin parameter can be derived by few measuRe.Ents 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.
This work pRe.Ents 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 measuRe.Ent, 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.
Electrorheological measuRe.Ents repRe.Ent a key approach in characterizing the efficiency of electrorheological fluids. The rotational rheometers, the Physica MCR 501 (Anton Paar) equipped with an electrorheological cell and the Bohlin Gemini CVOR 150 (Malvern Instruments) modified for electrorheological experiments generate an electric field in two completely different ways. Each of the two generations has a specific influence on electrorheological measuRe.Ents. The experimental data were obtained and compared for a suspension of polyaniline powders mixed (10 wt%) in silicone oil. For a concentric-cylinders arrangement, it was shown that the data are fully comparable for both rheometers. However, for a parallel-plate arrangement, the data using the Physica MCR 501 provide higher values in comparison with both the corresponding plateplate data obtained with the Bohlin Gemini CVOR 150 and with the mutually comparable concentric cylinders data.► Cite this publication as follows:
Peer P, Stenicka M, Filip P, Pavlinek V: Comparison of Electrorheological Measurements Based on Different Methods of Electric Field Generation, Appl. Rheol. 24 (2014) 42875.
This study addresses the Taylor-Galerkin/pressure-correction solution of industrial high-speed Re.Erse 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.
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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 concRe.E or mortar. Since superplasticizers have become state of technology, today, concRe.E 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.
Currently more and more Re.Earches have been performing concerning the numerical simulation of the behavior of fresh concRe.E during pumping or formwork filling. Adequate implementation of the rheology properties of fresh concRe.E is a determinant key to obtain realistic simulations. However, in many cases, the rheological parameters of the fresh concRe.E as determined by rheometers are not sufficiently accurate. The common principle of all the rheometers is not to measure directly the rheological parameters of concRe.E 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 tRe.Endous range of concRe.E flowing in the rheometer, using computational fluid dynamics (CFD). This allows to quickly and accurately obtain the rheological properties of fresh concRe.E, 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.
We describe and implement an efficient, open-source, multi-platform computer program ReSpect to infer the continuous and discRe.E relaxation spectra from dynamic moduli measuRe.Ents obtained by small-angle oscillatory shear experiments. We employ nonlinear Tikhonov regularization and the Levenberg-Marquardt method to extract the continuous relaxation spectrum. To obtain the discRe.E relaxation spectrum, we introduce a novel algorithm that exploits the continuous spectrum to position the modes. It uses a simple criterion which balances accuracy and conditioning of the resulting least-squares problem to determine a parsimonious number of modes. The end result is an easy-to-use, and easy-to-extend program, which can be used from the command-line or from a graphical user interface to override some of the default algorithmic choices. © 2013 Applied Rheology.► Related Software ReSpect available for free download at mathworks. ►
► Cite this publication as follows:
Takeh A, Shanbhag S: A Computer Program to Extract the Continuous and Discrete Relaxation Spectra from Dynamic Viscoelastic Measurements, Appl. Rheol. 23 (2013) 24628.
The aim of the pRe.Ent work was to predict the extrudate swelling behavior of organoclay containing Acrylonitrile- Butadiene-StyRe.E (ABS) nanocomposite. The modeling was performed on the basis of unconstrained recovery concept originally introduced by Tanner but employing Wagner viscoelastic model with generalized Wagner damping function which is believed to be capable of taking into account the effect of organoclay on viscoelastic properties of nanocomposite sample. This approach enabled us to evaluate the effect of organoclay on extrudate swell in terms of disentanglement kinetics and chain relaxation behavior. In our modeling, the effect of die entrance region on the extent of extrudate swelling was also considered. In order to evaluate the validity of our modeling, the extrudate swell was measured as a function of wall shear stress for samples varying in organoclay content. The results predicted from the model were found to be in relatively good agreement with the experimental results.► Cite this publication as follows:
Saadat A, Nazockdast H, Sepehr F, Mehranpoor M: Viscoelastic modeling of extrudate swell of Acrylonitrile-Butadiene-Styrene/Clay nanocomposite, Appl. Rheol. 23 (2013) 12131.
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Fischer P: Polymer Physics - Applications to Molecular Association and Thermoreversible Gelation (F. Tanaka), Appl. Rheol. 22 (2012) 235.
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.
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Elkins C, Aumaitre E: Lorentz Center Workshop: Dynamics of Complex Fluid-Fluid Interfaces, Appl. Rheol. 22 (2012) 145.
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 measuRe.Ents. 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 Re.Erse 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.
The measuRe.Ent of elongational viscosity still evokes a series of problems in comparison with the relatively well-established measuRe.Ent of shear viscosity. Re.Ently new techniques have appeared enabling measuRe.Ent of elongational viscosity with the samples for which the aspect ratios of their geometrical shapes (i.e. length vs. width (diameter)) can attain moderate values, i.e. not necessarily of a longitudinal character as in the case of earlier techniques. The aim of this contribution is to experimentally demonstrate the invariantness of transient uniaxial elongational viscosity measured with respect to a rectangular shape and thickness of LDPE samples using a SER Universal Testing Platform fixed in an Anton Paar MCR 501 host system. The width of the samples was varied within the range 2.1-12.7 mm and thickness altered within 0.1-1 mm. An advantage of fixing polymer samples directly to both drums (if possible) over the application of clamps is documented.► Cite this publication as follows:
Filip P, Svrcinova P: Measurement of elongational viscosity of polymer melts using SER Universal Testing Platform, Appl. Rheol. 22 (2012) 14776.
A high torque vane rheometer is used to measure the yields stress of cement-based materials. It is shown that this apparatus is suitable for the evaluation of the yield stress of various concRe.Es and mortars in the fresh state in comparison with slump tests realized with ASTM Abrams cone. Then, the rheological properties (yield stress and shear flow behaviour) of a homogeneous kaolin clay suspension are studied with the apparatus and favourably compared with other rheometers and geometries.► Cite this publication as follows:
Estelle P, Lanos C: High torque vane rheometer for concrete: principle and validation from rheological measurements, Appl. Rheol. 22 (2012) 12881.
A new conceptual non-contact method for liquid viscosity measuRe.Ent 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 measuRe.Ent 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.
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Handge UA: Annual Meeting of the German Rheological Society: Recent Trends in Fundamental and Applied Rheology, Appl. Rheol. 21 (2011) 238.
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Greim M: Rheological Measurements of Building Materials (Regensburg 2011), Appl. Rheol. 21 (2011) 232.
An apparatus for small angle light scattering (SALS) and light transmission measuRe.Ents 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 Re.Earch 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.
This paper pRe.Ents an experimental facility that allows simultaneous viscosimetric and Particle Image Velocimetry measuRe.Ents on concentrated suspensions in a wide-gap Couette rheometer. The experimental procedure is detailed: the optical characteristics of the index-matched suspension are carefully studied, the bottom end effect on both the viscosimetric measuRe.Ents and the recorded velocity profiles are analysed. First the experimental procedure is tested on a Newtonian fluid whose viscosity is known. The spatial and time resolutions of our device are shown to be 200 μm and 100 ms. The precision of the local viscosity measuRe.Ent is evaluated to better than 4 %. Then we show that the device can be used to characterize the rheological behaviour of a 47 %-concentrated suspension of 30 μm spheres. According to the particles large size, the Brownian motion can be neglected. However, colloidal interaction are still noticeable.► Cite this publication as follows:
Blanc F, Peters F, Lemaire E: Particle Image Velocimetry in concentrated suspensions : Application to local rheometry, Appl. Rheol. 21 (2011) 23735.
The classification of a concRe.E 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 pRe.Ent work is to correlate the rheological parameters of SCC matrix, yield stress and plastic viscosity, to slump flow measuRe.Ents. 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 Re.Ealed that the time for a spread of 500 mm which is used in engineering practice as Re.Erence for measuRe.Ent 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 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 Re.Erred to as 'nanofluids,' are currently being Re.Earched for their potential to function as heat transfer fluids. In a Re.Ently 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.► Cite this publication as follows:
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.
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.► Cite this publication as follows:
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.
A review of rheological in situ measuRe.Ent techniques applied to liquids and soft solids at high pressures of more than 100 MPa is pRe.Ented.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 measuRe.Ent techniques are classified with respect to the possibility of carrying out an absolute measuRe.Ent. Some typical experimental problems and error sources connected with high-pressure conditions are outlined and briefly discussed. The majority of the measuRe.Ent 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.► Cite this publication as follows:
Kulisiewicz L, Delgado A: High-pressure rheological measurement methods: A review, Appl. Rheol. 20 (2010) 13018.
Rheological characterisation of mortar is complicated by phenomena of slip, the formation of shear bands and depletion. At relatively low solid fractions a typical Couette geometry and a medium-size mixer-type rheometer were used to determine flow curves. At higher solid fractions a large-size coaxial cylinder rheometer with multiple blade vane geometry was used up to the point where slippage occurred. The viscosity as a function of concentration responds to the Krieger-Dougherty law, when a mortar is considered as a suspension of sand in a matrix of binder slurry. The limits of this description corresponds to a critical solid fraction above which air is entrapped during the mixing procedure: air content measuRe.Ents demonstrate this phenomenon. A clear relationship between mortar and slurries was established, based on the measured properties of both binder and sand particles, and on the Farris model for polydisperse suspensions. Intrinsic viscosity can be used as a tool to evaluate shape characteristics of the binder particles. A procedure for mixture optimisation of mortars using this model is demonstrated for the case of a trimodal mortar.► Cite this publication as follows:
Hendrickx R, Rezeau M, VanBalen K, VanGemert D: Mortar and paste rheology: concentration, polydispersity and air entrapment at high solid fraction, Appl. Rheol. 19 (2009) 52550.
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.► Cite this publication as follows:
McIntyre EC, Filisko FE: Squeeze Flow Rheology of Zeolite Suspensions, Appl. Rheol. 19 (2009) 44322.
► Cite this publication as follows:
Greim M: Rheology of Building Materials, 17th Conference, Univ. of Appl. Science, Regensburg, Mar 2008, Appl. Rheol. 18 (2008) 375.
In practice, while placing concRe.E in a formwork by pumping, the pressure generated by the pump is not controlled. In order to enhance the safety on the worksite, and in view of the current economic and ecologic arguments, it would be useful to dispose of an equation able to predict pressure losses based on the rheological properties of the concRe.E and the pipe configuration. This paper describes the derivation of an extended version of the Poiseuille formula, for shear-thickening materials with a yields stress, described by the modified Bingham equation. This formula is applied to flow-tests with self-compacting concRe.E. The results prove the applicability of this extended Poiseuille formula, showing that the flow is occurring in laminar regime, with no significant wall slip.► Cite this publication as follows:
Feys D, Verhoeven R, DeSchutter G: Extension of the Poiseuille formula for shear-thickening materials and application to Self-Compacting Concrete, Appl. Rheol. 18 (2008) 62705.
► Cite this publication as follows:
Mitchell G, Davis F, Vaughan A, Mossman S: 75 Years of Polyethylene: Past Successes and Future Challenges, Appl. Rheol. 18 (2008) 316.
Investigations of rheological properties of ferrofluids have shown strong changes of the viscosity in magnetic fluids with an applied magnetic field. The change of the viscosity . the magnetoviscous effect . can theoretically be described with chain and structure formation under the influence of a magnetic field. Moreover, the formation of these structures leads to the appearance of viscoelastic effects or other non-Newtonian features like yield stress in ferrofluids with an applied magnetic field. With a shear rate controlled rheometer . as it as been used in former experiments . the yield stress could not be investigated directly. Therefore the results concerning a field dependent yield stress based on an extrapolation of shear controlled measuRe.Ents. For the direct investigations of the yield stress, a dedicated stress controlled rheometer is required, allowing direct investigations of the magnitude and field dependence of this effect. In this work the design of the stress controlled rheometer with its main parameters has been described in detail. The rheological investigations with differently composed fluids show that the stress controlled rheometer enables direct measuRe.Ents of even small yield stresses in ferrofluids as well as large effects like they are found in magnetorheological fluids (MRF).► Cite this publication as follows:
Shahnazian H, Odenbach S: New driving unit for the direct measurement of yield stress with a stress controlled rheometer, Appl. Rheol. 18 (2008) 54974.
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 Re.Earch 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 pRe.Ent main theoretical Re.Earch 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.► Cite this publication as follows:
Bjorkman U: The Nonlinear History of Fibre Flow Research: Part 2. Continuation, Reflections and Suggestion, Appl. Rheol. 18 (2008) 34694.
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 Re.Earch 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 pRe.Ent 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 pRe.Ented.► Cite this publication as follows:
Bjorkman U: The Nonlinear History of Fibre Flow Research: Part 1. Background and Beginning, Appl. Rheol. 18 (2008) 23974.
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 measuRe.Ents 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.
► Cite this publication as follows:
Winter HH: Rheology Cyberinfrastructure for Integrated Research and Learning at ARC07, Appl. Rheol. 17 (2007) 302.
Self-Compacting ConcRe.E is a new type of concRe.E which is more liquid compared to traditional concRe.E and which does not need any form of external compaction. As a result this type of concRe.E 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).► Cite this publication as follows:
Feys D, Verhoeven R, DeSchutter G: Evaluation of time independent rheological models applicable to fresh Self-Compacting Concrete, Appl. Rheol. 17 (2007) 56244.
Rheo-optics is a method that allows the analysis of optical properties, like birefringence and dichroism under steady and oscillatory shear. It is possible to correlate macroscopic mechanical responses with induced microscopic changes in the material. We describe how this method was improved several fold and implemented on a commercially available setup. However, the here pRe.Ented ideas are applicable to any rheo-optical setup, based on modulation of the laser light. Additionally it does not need a lock-in amplifier and therefore reduces the costs of the setup.► Cite this publication as follows:
Klein C, Venema P, Sagis L, vanDusschoten D, Wilhelm M, Spiess HW, vanderLinden E, Rogers SS, Donald AM: Rheo-optical Measurements using Fast Fourier Transform and Oversampling, Appl. Rheol. 17 (2007) 45210.
Nowadays it is necessary to perform experimental measuRe.Ents 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 measuRe.Ents (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 measuRe.Ents 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.
The effects of free surface shape on normal stress difference measuRe.Ents in cone and plate flow are investigated. The analysis shows that the stress field is significantly altered by deviations of the free surface from an ideal (spherical) shape. For the cone and partitioned plate technique, it is shown how modest deviation from a spherical free surface shape can lead to errors of roughly 10% in the measured normal stress differences.► Cite this publication as follows:
Venerus DC: Free Surface Effects on Normal Stress Measurements in Cone and Plate Flow, Appl. Rheol. 17 (2007) 36494.
Models of kinetic theory provide a coarse-grained description of molecular configurations wherein atomistic processes are ignored. The Fokker-Planck equation related to the kinetic theory descriptions must be solved for the distribution function in both physical and configuration spaces. When the model involves high dimensional spaces (including physical and conformation spaces and time) standard discretization techniques fail due to excessive computation requiRe.Ents. In this paper, we revisit some model reduction techniques Re.Ently proposed to circumvent those difficulties, exploring other new application areas related to entangled polymer models as well as the use of such reduced models for treating complex flows in which the distribution function involves both the physical and the conformation coordinates.► Cite this publication as follows:
Mokdad B, Pruliere, re E, Ammar A, Chinesta F: On the simulation of kinetic theory models of complex fluids using the Fokker-Planck approach, Appl. Rheol. 17 (2007) 26494.
A specific twin channel slit die was used to measure in-line the viscous behaviour of an extruded wheat starch. This allows to put in evidence the influences of temperature, water content and specific mechanical energy (SME). The proposed rheological law permits to satisfactorily predict the viscosity of a wheat starch for any processing condition. Original results are pRe.Ented for the behaviour of cationic starches obtained by reactive extrusion.► Cite this publication as follows:
Berzin F, Tara A, Tighzert L: In-line measurement of the viscous behaviour of wheat starch during extrusion. Application to starch cationisation., Appl. Rheol. 17 (2007) 21222.
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 pRe.Ence 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.
The measuRe.Ent 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.
This paper deals with a Magnetic Resonance micro-Imaging (MRI) analysis of asymptotic kinematics which is a condition adopted in some rheological characterisations. Asymptotic kinematics (for example the slow shearing ) aim is to evaluate material properties at ''equilibrium'', avoiding structural changes induced by external stimuli. Measured material functions in these mechanical conditions deal with the structure/morphology of materials and can be used to investigate the structure as a function of the state variables only, as temperature, pressure and composition. In this paper MRI experiments were performed to study some shear flow behaviours of surfactant wormy micelles made by lecithin/water and diluted in cyclohexane (Re.Erse micellar phase L2). MRI was used as a non-invasive tool in order to follow the structural responses both during slow shearing and when the sample is stirred outside the linear behaviour range. Relations can be found between the typical NMR parameters, strictly related to the microstructure, and the rheological macroscopic parameters as zero-shear viscosity.► Cite this publication as follows:
Coppola L, Gabriele D, Nicotera I, Oliviero C: MRI Experiments as a Tool to Study Asymptotic-Shear Flow Behaviour of a Worm-Like Reverse Micellar Phase, Appl. Rheol. 16 (2006) 190.
The rheological behaviour of a cement paste used in Self-Compacting ConcRe.Es (SCC) formulations is compared to that of an 'ordinary' cement paste (OC) devoid of organic admixtures. In order to mimic the flow conditions experienced by the cement paste in the inter granular space of concRe.Es, the rheological behaviour is investigated in a squeeze flow geometry. By considering the evolution of the squeeze force for different velocities as a function of the instantaneous distance between the discs, it is found that the behaviors of the two cement pastes are qualitatively different. For the OC pastes, the force decreases with increasing squeeze velocity for any given discs separation, indicating that the material is undergoing fluid-solid separation due to filtration of the fluid phase through the porous media made up by the grains. Such behaviour reflects the very poor flowability of the OC paste. The behaviour of the SCC paste is qualitatively different. Above a certain critical value of the speed Uc, the force is an increasing function of the speed for any given disc separation. Under these flow conditions the rheological behaviour of the material is that of a viscous, although highly non-Newtonian, fluid which corresponds to the flowability conditions of the material. For squeeze speeds smaller than Uc, the rheological behaviour of the SCC paste is similar that of OC, indicating that below this critical velocity the material undergoes solid-fluid separation corresponding then to its non-flowability zone.► Cite this publication as follows:
Phan,PH, Chaouche M: Rheology and stability of self-compacting concrete cement pastes, Appl. Rheol. 15 (2005) 336.
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 pRe.Ent 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).► Cite this publication as follows:
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.
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 repRe.Entation of the material behavior than would extrapolation of the Prony series fit.► Cite this publication as follows:
Koenigsberg W, Selverian JH: Zone Method for Representing Relaxation Characteristics of Viscoelastic Materials, Appl. Rheol. 15 (2005) 160.
► Cite this publication as follows:
Greim M, Kusterle W: 14th Conference and Workshop 'Rheological Measurement of Building Materials', Regensburg/D, Appl. Rheol. 15 (2005) 124.
Viscosity measuRe.Ents 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 measuRe.Ents. 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 measuRe.Ents. 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.
► Cite this publication as follows:
Schweizer T: Handbook of Ellipsometry (Harland G. Tompkins, Eugene A. Irene, Eds.), Appl. Rheol. 15 (2005) 10.
The behaviour of Re.Erse micellar solution and Re.Erse hexagonal and lamellar liquid crystal phases in pluronic L64/water/p-xylene ternary system was investigated by rheological techniques. Samples with an increasing water content along the amphiphilic copolymer-lean side of the ternary phase diagram were analysed at different temperatures and a different behaviour was evidenced by both dynamic and steady tests for each considered phase, depending on the morphology of structure (micellar, lamellar, hexagonal phases). It was observed that the Re.Erse micelles size increases with increasing water concentration and decreases with increasing temperature, without any phase transition. On the contrary the normal micelles become anisometric on temperature, showing a transition to a liquid crystalline phase. The observed mechanical spectra of the liquid crystalline phases are typical of hexagonal and lamellar phases according to the literature. A phase transition with temperature was found for both liquid crystalline phase (lamellar and hexagonal) by rheological tests and was confirmed by ocular inspection.► Cite this publication as follows:
Coppola L, Gabriele D, Nicotera I, Oliviero C: Rheological Properties of the Reverse Mesophases of the Pluronic L64/P-Xylene/Water System, Appl. Rheol. 14 (2004) 315.
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 compRe.Ensive 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.
Particle fluid separation is studied in the case of slow squeezing flow of dense clay suspensions. The fluid pressure gradient generated by the test induces heterogeneity in the sample. Experimental water content measuRe.Ents at different time points through the test allow the quantification of this separation phenomenon. The problem equations are written in the case of purely extensional flow. Based on Terzaghi principle, Darcy.s law and a Cam Clay type constitutive equation, the influence of the permeability function on the predicted void ratio evolution is studied. It is then shown that a certain water amount is strongly linked to the grains and cannot be extracted from the sample using simple compression. This critical water amount is then taken in account in the permeability function in order to predict the compression load through the test.► Cite this publication as follows:
Roussel N, Lanos C: Particle Fluid Separation in Shear Flow of Dense Suspensions: Experimental Measurements on Squeezed Clay Pastes, Appl. Rheol. 14 (2004) 256.
The performance of tests with elastic liquids at high shear rates is cumbersome due to viscous dissipation heating, high normal forces, and - above all - edge fracture. This paper shows how such measuRe.Ents can be improved and simplified over the conventional cone-plate technique by using a partitioned plate. For a polystyRe.E melt with zero shear viscosity 44.5 kPas at 190.C, steady state viscosities can be obtained up to 100 s-1. For samples with twice the diameter of the sensing area of the tool, the strain beyond which disturbances can be noticed is about 2 - 3 times higher than for conventional cone-plate. As a consequence of the design, precise viscosity measuRe.Ents can be made without knowing the exact radius of the sample and without well centring it. This geometry is ideal for quick and dirty loading. Drawbacks are that the tool requires regular cleaning of the ring gap, that it can only be fitted to rheometers with a non-displacing force measuring cell (force rebalance transducer), and that it is not suited to measure low viscous systems such as polymer solutions.► Cite this publication as follows:
Schweizer T: A Quick Guide to Better Viscosity Measurements of Highly Viscous Fluids, Appl. Rheol. 14 (2004) 197.
Frequency sweep experiments were performed on poly(vinyl chloride) (PVC) and acrylonitrile butadiene rubber (NBR) as well as their miscible blends PVC/NBR (70/30), PVC/NBR (50/50), and PVC/NBR (30/70) in oscillatory shear. The samples were prepared by mechanical blending at 160.C. In order to investigate the validity of time temperature superposition (TTS) principle the loss angle d versus the logarithm of the absolute value of the complex modulus, G*, were plotted. It was shown that the TTS principle is not valid for the above-mentioned polymer materials and therefore they are not thermorheologically simple. Master curves of PVC, NBR, and PVC/NBR (50/50) blend were therefore obtained approximately. Using a nonlinear regression method, discRe.E relaxation spectra were determined for PVC, NBR, and PVC/NBR (50/50). To study non-linear viscoelasticity behavior, the experiments of steady shear, start up steady shear, and step strain were carried out. The damping function was determined by the step strain experiments. Using K-BKZ constitutive equation, the shear viscosity and the shear stress growth function were calculated from the discRe.E relaxation spectra and the damping function and then compared to experimental data. The K-BKZ constitutive equation provides very good prediction over the entire range of experimental results.► Cite this publication as follows:
Sodeifian G, Haghtalab A: Discrete Relaxation Spectrum and K-BKZ Constitutive Equation for PVC, NBR and Their Blends, Appl. Rheol. 14 (2004) 180.
► Cite this publication as follows:
Greim M, Kusterle W: Rheological Measurement of Building Materials (Regensburg, Germany), Appl. Rheol. 14 (2004) 148.
► 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.
Previous studies involving rheological measuRe.Ent of semi-solid foods have reported a large amount of data variability, but have focused little on understanding the cause of such variability. This project examined whether differences in normal force have an effect on the variability of rheological measuRe.Ents. Experimental methods focused on error introduced during sample loading; specifically whether normal force application during loading influenced the storage (G.) and loss (G.) moduli of semi-solid and liquid foods. Samples were loaded to 5 or 20 N between the parallel plates of a TA-1000N rheometer and tested immediately. For all semi-solid products tested, normal force application during sample loading did significantly affect oscillatory parameters, with G. and G. measuRe.Ents increasing up to 50 % with greater normal force. However, loading normal force did not significantly influence the parameters measured for the liquid sample. This suggests that differences in normal force during loading could be a significant source of data variability during rheological measuRe.Ent of semi-solid products.► Cite this publication as follows:
Pearce MAD, Bellmer DD: Data Variability in Rheological Measurement of Semi-Solid Foods: Effects of Loading Normal Force, Appl. Rheol. 12 (2002) 282.
Large amplitude oscillatory shear (LAOS) was applied to a linear polymer melt in order to study the mechanical harmonic generation in the nonlinear regime. In the nonlinear regime mechanical harmonics at 3w1, 5w1, etc. are generated under oscillatory shear with a shear frequency w1. These higher harmonics can be analysed with respect to frequencies, amplitudes and phase if the time data of the torque is Fourier transformed. This experimental method (FT-Rheology) permits therefore to quantify the mechanical nonlinearities if sinusoidal shear rates are applied. This article describes the basic idea of this experimental method as well as the application to different anionically polymerized polystyRe.E melts. The dependence of the nonlinear, rheological properties with respect to the molecular weight Mn, the applied strain g0, the frequency w1 and the temperature was investigated. In addition to simple nonlinear theories we could also observe even harmonics at 2w1, 4w1, etc. in the FT-rheology spectra. The appearance of even harmonics was correlated with the appearance of a more complex nonlinear behaviour.► Cite this publication as follows:
Neidhö, fer T, Wilhelm M, Spiess HW: Fourier-transform-rheology on linear polystyrene melts, Appl. Rheol. 11 (2001) 126.
An electrorheological fluid (ERF) (magnetorheological fluid - MRF) is a particulate suspension which shows a dramatic increase in flow resistance upon application of an external electric (magnetic) field. In both systems, the fundamental physical process is believed to be that the field induces polarization of each particle with respect to the carrier material, and the resulting interparticle forces cause elongated aggregates of particles to form in the field direction. While Re.Ent years have witnessed the appearance of several applications using these tunable flow properties, optimal use of this technology is still hindered by our incomplete understanding of the underlying mechanisms. This paper surveys our current understanding of several of the key issues governing the rheological behavior of MRF and ERF, with particular focus on Re.Ent progress made in important areas such as the behavior under high fields, sedimentation, temperature dependence, effect of wall surface conditions, and advances made in developing practical modelling strategies.► Cite this publication as follows:
See H: Mechanisms of magneto-and electro-rheology: Recent progress and unresolved issues, Appl. Rheol. 11 (2001) 70.
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.► Cite this publication as follows:
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.
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Talbi-Boucenna I, Quemada D: Transient measurements in rate controlled rheometers: a new method of standardization, Appl. Rheol. 10 (2000) 280.
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He X: 9th international conference on discrete simulation of fluid dynamics, Appl. Rheol. 10 (2000) 254.
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Barnes HA: An appreciation and critique of the suspension rheology research of, Appl. Rheol. 10 (2000) 248.
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Weigand J: Viscosity Measurements on Powders with a new Viscometer, Appl. Rheol. 9 (1999) 204.
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Giles D, Williams D: University of Minnesota holds its 24th annual short course on rheological measurements, Appl. Rheol. 9 (1999) 172.
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Gampert B, Wilkes C, Eich T: The Viscosity of Extremely Low Concentrated Anionic Polyelectrolyte Solutions, Appl. Rheol. 9 (1999) 158.
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Brummer R, Hetzel F, Harder C: Correlation of Polymer Properties with Dynamic Mechanical Measurements, Appl. Rheol. 7 (1997) 173.
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Ehrecke P: Reversible Deformation and irreversible Network Disentanglement of Polymer Melts, Appl. Rheol. 7 (1997) 67.
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Rech B: Measurements Errors during Characterization of ERFs with Rotational Viscometers, Appl. Rheol. 6 (1996) 261.H Heber
Flow Enhancer for ConcRe.E Suspension
Appl. Rheol. 6:5 (1996) 209 ►
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Heber H: Flow Enhancer for Concrete Suspension, Appl. Rheol. 6 (1996) 209.
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Senge B, Schwarzlos M, Blochwitz R, Annemuller G: Rheological Examination of Mashing in Brewery Process, Appl. Rheol. 6 (1996) 11.
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Bö, se N, Broeke H: Reducing Measurement Uncertainty of a High Pressure Capillary Viscometer, Appl. Rheol. 5 (1995) 190.W Gleissle
Rheological MeasuRe.Ents for Quality and Process Control
Appl. Rheol. 5:1 (1995) 14 ►
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Gleissle W: Rheological Measurements for Quality and Process Control, Appl. Rheol. 5 (1995) 14.
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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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Janocha H, Rech B: Measurements on Electroreological Liquids with Rotational Viscometers, Appl. Rheol. 3 (1993) 39.
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