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Nour el Hou Belkham, Abdelaziz Mehamha, Djafer BenachourAuthor index ►
Rheological behavior of alumina ceramic pastes
Appl. Rheol. 19:6 (2009) 64969 (corrected proof) ►
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.► Cite this publication as follows:
Belkham NEH, Mehamha A, Benachour D: Rheological behavior of alumina ceramic pastes, Appl. Rheol. 19 (2009) 64969.
The viscoelastic performance indicators of a commercial roofing membrane and an ecological bituminous membrane, which contains EVA copolymer from disused greenhouses and filler from landfill, are investigated. Rheological methods reveal as a useful tool to investigate basic and technical aspects of these materials. It is shown that using an extrusion rheometer adapted to measure the flexibility at low temperatures and measuring the tackiness by means of a plate-plate rheometer, constitute basic experiments that help to Develop new membranes. UnDer these premises, it is Demonstrated that the ecological membrane is a performing material, whose sole shortcoming is a slightly higher application temperature.► Cite this publication as follows:
Goikoetxeaundia G, Fernandez M, Munoz E, Santamaria A: Rheology applied to investigate roofing membranes: The case of an ecological alternative, Appl. Rheol. 19 (2009) 62305.
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.► Cite this publication as follows:
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.
Experimental and numerical studies have been unDertaken to check the influence of a magnetic field on the viscosity of liquid GaInSn with suspenDed solid particles.The rheological investigations show a significant change of the slope of the measured flow curves between the situation B = 0 and 0.02 T. By means of numerical simulations of the flow in the presence of Lorentz forces it could be shown that the influence of magnetohydrodynamic damping of the flow reduces the measured changes but does not annihilate them. As conclusion a 15 % change of viscosity of the melt in a magnetic field with B = 0.02 T could be fixed.► Cite this publication as follows:
Borin D, Nikrityuk P, Odenbach S: On the magnetic field influence on the viscosity of liquid GaInSn with suspended solid particles, Appl. Rheol. 19 (2009) 61995.
"Single-point" equations used for intrinsic viscosity Determination are greatly used when working with synthetic polymer solution systems. In this work we have applied them to a biological macromolecule in a bovine serum albumin (BSA)/water system. Almost all single-point equations are available and errors can be lowered. However, we have Detected a systematic bias in the estimations proviDed by "single-point" methods. To overcome it we propose a "double-point" method which gives lower estimation errors for this system. This novel method is not system specific and could be applied to other polymeric solution.► Cite this publication as follows:
Curvale R, Cesco C: Intrinsic viscosity determination by 'single-point' and 'double-point' equations, Appl. Rheol. 19 (2009) 53347.
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 measurements 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.
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.► Cite this publication as follows:
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 September 2009 - February 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.► Cite this publication as follows:
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.► Cite this publication as follows:
Bjorkman U: The non-Newtonian Fluid Mechanics of Technical Fibre Suspensions: Compressive Flows, Appl. Rheol. 19 (2009) 44290.
The combined effect of charged addition and molecular weight, Mw, on the thermal gelation and gel dissolution of poly(NisopropylacrylamiDe) chains was explored by using Rheological techniques. The synthesized charged Derivative is poly(N-isopropylacrylamiDe co-Acrylic acid). The rheological behavior of the two macromolecules is clearly different: the thermal gelation of the high Mw and charged macromolecule is much more accentuated. This suggests that the gelation at high temperatures only occurs when the inter polymer aggregate distance is sufficiently short to allow polymer bridging; this situation can be achieved by different approaches, such as increasing polymer concentration and increasing polymer persistence length and polymer Mw.► Cite this publication as follows:
Antunes FE, Gentile L, Tavano L, OlivieroRossi C: Rheological characterization of the thermal gelation of poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide)co-Acrylic Acid, Appl. Rheol. 19 (2009) 42064.
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.► Cite this publication as follows:
Niedzwiedz K, Arnolds O, Willenbacher N, Brummer R: Capillary Breakup Extensional Rheometry of Yield Stress Fluids, Appl. Rheol. 19 (2009) 41969.Christian Wagner
Rheologentagung 2009 Berlin
Appl. Rheol. 19:3 (2009) 179-179 ►
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Wagner C: Rheologentagung 2009 Berlin, Appl. Rheol. 19 (2009) 179.J.K.G. Dhont, G. Gompper, D. Richter
Julich Soft Matter Days 2008
Appl. Rheol. 19:3 (2009) 176-178 ►
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Dhont JKG, Gompper G, Richter D: Julich Soft Matter Days 2008, Appl. Rheol. 19 (2009) 176.
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.► Cite this publication as follows:
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.► Cite this publication as follows:
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.► Cite this publication as follows:
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.
We present an experimental study of the stability of the Taylor-Dean flow of well characterized suspensions of solid disks occurring between two horizontal coaxial cylinDers. The inner cylinDer is rotating and the outer cylinDer is at rest. By means of a visualization technique, we Determine the shape of the vortices which take place in the flow at the onset of the instability and the corresponding critical parameters against the flake concentration and the system aspect ratio.► Cite this publication as follows:
Daimallah A, Bouabdallah A, Nsom B, Adnane M, Alemany A: Onset of Instabilities in Taylor-Dean Flow of Yield-Stress Fluid, Appl. Rheol. 19 (2009) 33960.
The specific properties of bentonite such as hydration, swelling,water absorption, viscosity, yield stress and thixotropy make it a valuable material in the form of mineral powDer for a wiDe range of uses in agronomy, cosmetics and civil engineering. A flow curve is a quick test used to evaluate the rheological basic properties of a viscous fluid. However, many bentonite dispersions exhibit a complex flow curve, with yield stress and thixotropy area, especially at high concentration. In this study, flow curves from raw and activated bentonites dispersed in water were acquired at 6, 8 and 10% mass concentrations. Five stages along the flow curve were iDentified.To explain each stage, rheograms obtained from a dispersion maDe with a moDel material were studied in Depth. The moDel material was a smectite extracted from a raw bentonite then saturated with calcium or sodium. Many homoionic and bi-ionic dispersions were prepared at various concentrations. The analysis and the moDelling of some creep-recovery tests by a Zener moDel showed the relationship between the initial stage in the flow curve, named AB stage, and the viscoelastic properties of the fluid. The AB stage corresponds to the Deformation of the material in the solid state. The τB point corresponds to an intermediate yield stress between the solid state and the start of the heterogeneous fracturation. The study of many bi-ionic dispersions allowed drawing the evolution of the yield stress as a function of concentration and saturation. The composition of the raw bentonites was expressed as an equivalent bi-ionic dispersion by calculating an active smectite percentage. A good correlation was obtained at the highest concentrations between τB from the bi-ionic moDel dispersions and the raw bentonites dispersions► Cite this publication as follows:
Paumier S, Pantet A, Monnet P, Touze-Foltz N: Evaluation of the viscoelastic properties of a clay material using a flow curve, Appl. Rheol. 19 (2009) 23824.
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.► Cite this publication as follows:
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.► Cite this publication as follows:
Lionetto F, Maffezzoli A: Rheological characterization of concentrarted nanoclay dispersions in an organic solvent, Appl. Rheol. 19 (2009) 23423.
An optimised method for the Detection and analysis of the time DepenDent pressure associated with the Development of melt flow instabilities during extrusion through a capillary die was Developed and validated. The magnituDe and frequency of the Developed quasi-periodic distortions, as well as the pressure profiles along the die length, were found to Depend on the MWD, topology, melt elasticity and uniaxial extensional flow properties. Both the onset and magnituDe of strain harDening in uniaxial extension appear to be related to the onset for the Development of melt flow instabilities unDer capillary flow. For a better unDerstanding of the role of the extensional properties (namely that of a purely elastic instability) the Hencky strain to failure was also Determined and correlated to the observed flow instabilities. Time resolution of the capillary rheometer was improved by a factor of 1000, pressure resolution by a factor of 100 compared to the original set-up.► Cite this publication as follows:
Filipe S, Becker A, Barroso VC, Wilhelm M: Evaluation of melt flow instabilities of high-density polyethylenes via an optimised method for detection and analysis of the pressure fluctuations in capillary rheometry, Appl. Rheol. 19 (2009) 23345.
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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.
Steady state and transient rheological behaviours of a one-coat renDer mortar are consiDered experimentally using a shear rheometer equipped with the vane geometry.The flow curves performed at controlled shear-rates exhibit highly pronounced minima, which is attributed to shear localization and strong thixotropy. This latter property is further investigated separately by consiDering the temporal growth of the apparent stress at very low shear-rate, reflecting the material's microstructure rebuild up following shearing at different high shear rates. It is found that rebuilding characteristic time is roughly inDepenDent upon shear history, indicating that this is a material parameter. The influence of water dosage rate on the rheological behaviour is consiDered. As expected, apparent viscosity and yield stress Decrease with increasing kneading water amount. The rebuilding up kinetics is found to be non sensitive to water dosage rate, suggesting that the material's processability would be preserved when changing this parameter, although significant creeping may be expected at high water dosage rates.► Cite this publication as follows:
Kaci A, Chaouche M, Andreani P-A, Brossas H: Rheological behaviour of render mortars, Appl. Rheol. 19 (2009) 13794.
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► Cite this publication as follows:
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.► Cite this publication as follows:
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.► Cite this publication as follows:
Ternik P, Marn J: Numerical study of blood flow in stenotic artery, Appl. Rheol. 19 (2009) 13060.
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.► Cite this publication as follows:
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.► Cite this publication as follows:
Aho J, Syrjala S: Evaluation of different methods for determining the entrance pressure drop in capillary rheometry, Appl. Rheol. 18 (2008) 63258.
In practice, while placing concrete 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 concrete 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 concrete. 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.
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.► Cite this publication as follows:
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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Schaffler M, Miller R: User Seminar of 2D and 3D Rheology of Fluids and Liquid Interfaces, Appl. Rheol. 18 (2008) 318.
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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.
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Fischer P, Nicolai T: Food Colloids 2008 - Creating Structure, Delivering Functionality, Appl. Rheol. 18 (2008) 315.
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 measurements. 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 measurements 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.
Rheological properties of elastomeric nanocomposites with organically modified Montmorillonite clays, as possible replacements or supplements to classical active fillers, such as carbon black or silica, have been intensively studied in recent years. Possessing large specific surface areas acquired through the melt-mixing processes of elastomeric intercalation and subsequent filler exfoliation, the clay particles have inDeed proved to be highly eligible reinforcing and thermally stabilizing ingredients for application in elastomers. In fact, their performance has shown to be in many respects superior to that of classical fillers, particularly owing to some unusual, though beneficial, exhibited properties. Namely, apart from uncommonly high surface activity, manifested by creation of a host of van Der Waals type secondary linkages with elastomer molecules, the main curiosity of clay filler is its dissipative action. Using dynamic mechanical functions unDer different Deformational and temperature conditions, as means for rheological characterization of nanocomposites, the foregoing nano-scale traits are clearly reflected in substantial stiffness at low strains and, unexpectedly, dwindling energy loss with increasig filler content and/or Decreasing temperature. BesiDes, rheological analysis of this kind, together with appropriate theoretical grounds, has enabled elucidation of peculiar conduct, as well as macroscopic insight into the very nature of secondary interactions in elastomers.► Cite this publication as follows:
Susteric Z, Kos T: Rheological Idiosyncrasies of Elastomer/Clay Nanocomposites, Appl. Rheol. 18 (2008) 54894.
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.► Cite this publication as follows:
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.► Cite this publication as follows:
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.
Water soluble polymers such as cellulosic or starch ethers are often incluDed in the mix-Design of Self Compacting Concretes (SCCs) in orDer to improve their stability and robustness. The stability, including resistance to liquid-solid separation and sedimentation, may be attributed to the increase of the viscosity of the liquid phase due to the thickening effect of the polymer. The later is then referred to as a Viscosity-Modifying Admixture (VMA). In the present study, we consiDer the influence of VMAs on the rheological properties of the material at cement scale level. In particular, the change in the thixotropic properties of the cement paste due to the inclusion of VMA is investigated. It is found that addition of VMA significantly enhances rebuild-up kinetics at rest following shearing at high shear rate. The influence of VMA on the steady state rheological properties is also consiDered. As reported in the literature, the yield stress is found to monotonically increase with VMA content, while the consistency presents a minimum indicating the existence of an optimum value of the VMA for which the workability of the cement paste is maximum.► Cite this publication as follows:
Bouras R, Chaouche M, Kaci S: Influence of Viscosity-Modifying Admixtures on the Thixotropic Behaviour of Cement Pastes, Appl. Rheol. 18 (2008) 45604.
In the present study, an evolution equation for the Cauchy stress tensor is proposed to take elastic, viscous and plastic characteristics of complex fluids simultaneously into account. In particular, hypoplasticity is incorporated to account for the plastic features. The stress moDel is applied to investigate time-DepenDent flows of an elasto- visco-plastic fluid driven by an oscillating boundary with/without an additional stationary boundary to study the cyclic responses and the moDel performance. Numerical simulations show that while different Degrees of elastic and viscous effects can be captured by varying the moDel parameters, plastic Deformation plays a significant role in the velocity distribution, and can be simulated appropriately by use of hypoplasticity. The stress moDel is capable of accounting for the combined elastic, viscous and plastic features of complex materials in transient motions, and applications may be found in geomorphic fluid motions like granular and Debris flows, and flows involving polymers.► Cite this publication as follows:
Fang C, Lee C: Unsteady parallel flows of an elasto-visco-hypoplastic fluid with oscillating boundary, Appl. Rheol. 18 (2008) 45001.
The yield stresses of five samples (two highly concentrated emulsions, two Kaolin dispersions and mayonnaise) were Determined in two ways. In one case, steady shear experiments were performed over a range of incrementally Decreasing shear rates. The resulting flow curves, plotted as shear stress against shear rate, clearly showed the existence of a yield stress for each sample, the Herschel-Bulkley moDel being fitted to obtain values. In the second case, oscillatory amplituDe sweeps were performed at three frequencies, and the .dynamic yield stress. was Defined as the stress at which Deviation from linearity occurred; this procedure has often been used to Determine the yield stress of emulsions. It was found that the dynamic yield stress is frequency DepenDent, and cannot therefore be thought of as physically meaningful material property. At no frequency did the dynamic yield stress correlate with the yield stress obtained from the flow curves.► Cite this publication as follows:
Masalova I, Malkin AY, Foudazi R: Yield stress as measured in steady shearing and in oscillations, Appl. Rheol. 18 (2008) 44790.
The main characteristics of geological flows such as Debris flows, avalanches and lahars is due to the relative importance of viscous versus inertial forces in the momentum balance.This paper consiDers the motion generated by the collapse of a damretaining mud, itself moDeled as a power-law fluid. The equation of motion is Derived in a non-dimensional form and solved analytically with the shallow-water assumption in a dry and smooth horizontal channel. Notably indicated are flow regimes and the effect of the reservoir length as well as the effect of mud rheology on flow Development. Then, a parametric study of this moDel is produced and the effect of mud shear-thinning on flow Development is pointed out.► Cite this publication as follows:
Nsom B, Ravelo B, Ndong W: Flow regimes in viscous horizontal dam-break flow of clayous mud, Appl. Rheol. 18 (2008) 43577.
► Cite this publication as follows:
Rheological Societies: Society's Site September 2008 - February 2009, Appl. Rheol. 18 (2008) 258.
► Cite this publication as follows:
Handge U: Symposium Rheology, Structure and Dynamics of Complex Fluids, Appl. Rheol. 18 (2008) 249.
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.► 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.
A methodology is presented to invert the flow equation of a Herschel-Bulkley fluid in Couette concentric cylinDer geometry, thus enabling simultaneous computation of the true shear rates, ΓHB, and of the three Herschel-Bulkley rheological parameters. The errors maDe when these rheological parameters are computed using Newtonian shear rates, ΓN, as it is normal practice by research and industry personnel, can then be estimated. Quantification of these errors has been performed using narrow gap viscometer data from literature, with most of them taken with oil-field rheometers. The results indicate that significant differences exist between the yield stress and the flow behavior inDex computed using ΓHB versus the parameters obtained using ΓN and this is an outcome of the higher ΓHB values. Predicted true shear rates and rheological parameters are in very good agreement with results reported by other investigators, who have followed different approaches to invert the flow equation, both for yield-pseudoplastic and power-law fluids.► Cite this publication as follows:
Kelessidis V, Maglione R: Shear rate corrections for Herschel-Bulkley fluids in Couette geometry , Appl. Rheol. 18 (2008) 34482.
A new procedure is Described to convert the vane torque and rotational velocity data into shear stress vs shear rate relationships. The basis of the procedure consists in consiDering locally the sheared material as a Bingham fluid and computing a characteristic shear rate from Couette analogy. The approach is first applied to experimental vane data of Newtonian fluid, then used to process vane experimental data of non-Newtonian and yield stress materials. Results, which are favourably compared with torsional flow, show that the approach correctly predicts the rheological behaviour of the materials investigated.► Cite this publication as follows:
Estelle, Lanos C, Perrot A, Amziane S: Processing the vane shear flow data from Couette analogy, Appl. Rheol. 18 (2008) 34037.
► Cite this publication as follows:
Schneider S: Methods to characterize electrorheological suspensions in consideration of the temperature influence (PhD thesis summary), Appl. Rheol. 18 (2008) 148.
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.
Electrorheological fluids (ERF) change viscosity when an electric field is applied. A special type of ERF consists of polyurethane particles which are doped with Li+ and/or Zn2+ cations and suspenDed in silicone oil.This article gives an overview of the temperature DepenDent behavior of the ER effect for these fluids and Describes the basic principles how this is explained. Chemical analyses proviDe information as a basis for a polarization moDel in several dimensions down to molecular size.► Cite this publication as follows:
Schneider S, Eibl S: Review of the Electrorheological (ER) Effect of Polyurethane-based ER Fluids, Appl. Rheol. 18 (2008) 23956.
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.
Small micellar casein particles were formed in aqueous solutions of native casein after addition of polyphosphate. These socalled submicelles aggregated and gelled with a rate that increased with increasing temperature.The evolution of the viscosity during this process was Determined at constant shear rate or shear stress. When applying a small shear stress the viscosity increased strongly until the shear rate became immeasurably slow, but when the applied shear stress exceeDed a critical value (σc) the aggregates broke up and the viscosity reached a maximum. At longer times the viscosity Decreased rapidly at first, followed by a very slow Decrease. sc was inDepenDent of the shear rate and heating temperature, but increased strongly with increasing casein concentration.At constant shear rate the stress remained close to σc, but fluctuated irregularly.After cessation of shear flow, gels were formed rapidly. Oscillation shear measurements for σ > σc showed a strongly non-linear response at the time of maximum viscosity.► Cite this publication as follows:
Pitkowski A, Nicolai T, Durand D: Shear flow and large amplitude oscillation shear study of solutions of aggregating micellar casein particles, Appl. Rheol. 18 (2008) 23050.
► Cite this publication as follows:
Rheological Societies: Society's Site March 2008 - August 2008, Appl. Rheol. 18 (2008) 60.
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.► Cite this publication as follows:
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.► Cite this publication as follows:
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]► Cite this publication as follows:
Mitsoulis E, Mavrantzas V: Numerical Methods for Non-Newtonian Flows - XVth IWNMNNF 2007, Appl. Rheol. 17 (2007) 354.
Genetic Programming (GP) is used to estimate the functions that Describe the torque and the force acting on the external sphere due to steady state motion of viscoelastic fluid between two eccentric spheres. The GP has been running based on experimental data of the torque at different eccentricities to produce torque for each target eccentricity. The angular velocity of the inner sphere and the eccentricity of the two spheres have been used as input variables to find the discovered functions. The experimental, calculated and predicted torque and forces are compared. The discovered function shows a good match to the experimental data.We find that the GP technique is a good new mechanism of Determination of the force and torque of fluid in eccentric sphere moDel.► Cite this publication as follows:
Elbakry M, Radi A: Genetic programming approach for flow of steady state fluid between two eccentric spheres, Appl. Rheol. 17 (2007) 68210.
The assumptions implicit in the simplified expressions used to convert the torque-rotational speed data of parallel-disk viscometry into rim shear rate and rim shear stress are iDentified. The rim shear stress generated by the simplified expression is compared against the actual rim shear stress. The error involved is quantified for two standard rheological moDels and for a set of laboratory data. UnDer normal operation conditions of parallel-disk viscometers this error was found to be within the acceptable limit. However, for highly shear thinning fluids and for fluids exhibiting yield stress this error can become very large. The suitability of the approximate rim shear stress in wall slip Determination is then briefly discussed.► Cite this publication as follows:
LeongYeow Y, Leong Y, Khan A: Error Introduced by a Popular Melthod of Processing Parallel-Disk Viscometry Data, Appl. Rheol. 17 (2007) 66415.
The dynamic viscoelastic properties of liquid crystalline polymer (LCP) and polyethylene terephthalate (PET) blends were studied at two different temperatures: 265 oC at which LCP was in solid state and 285 oC at which LCP was in molten state. The PET was in molten state at both the temperatures. The storage modulus, G', loss modulus, G'', dynamic viscosity, η', of blends with different compositions were evaluated and compared. The morphology of these samples was studied using scanning electron microscope, which exhibited composition DepenDency. A maxima was observed in the viscosity versus composition plot corresponding to 90/10 LCP/PET blend at 285oC. The G' versus G'' plots Demonstrated the composition DepenDency of LCP/PET blends.► Cite this publication as follows:
Hashmi SAR, Kitano T: Effects of State Change of Liquid Crystalline Polymer on Dynamic Visco-elasticity of its Blends with Polyethylene-terephthalate, Appl. Rheol. 17 (2007) 64510.
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.► Cite this publication as follows:
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.
► Cite this publication as follows:
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).► 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.
The elongational flow of polymethylmethacrylate / nano-clay composites was studied during stressing and creep experiments using a Müt tensile rheometer (MTR). The dispersion of the nano-clay was controlled by means of transmission electron microscopy (TEM) and the layer distance was measured with X-ray diffraction (XRD).With growing volume fraction of the filler an increase of the viscosity is observed unDer constant strain rate and constant stress conditions. The results for the elongational viscosities for both moDes are consistent with each other. Furthermore, a strain softening behavior can be measured, which is the more pronounced the higher the nano-clay content is. As the Trouton rule is not valid, Deviations from the linear behaviour are related to an envolope curve for the elongational viscosities instead of the threefold zero shear viscosity.► Cite this publication as follows:
Katsikis N, Koniger T, Munstedt H: Elongational viscosities of polymethylmethacrylate / nano-clay composites, Appl. Rheol. 17 (2007) 52751.
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.
► Cite this publication as follows:
Rheological Societies: Society's Site September 2007 - February 2008, Appl. Rheol. 17 (2007) 238.
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 presented 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.
Rheological and mechanical properties of acrylonitrile-butadiene-styrene polymers (ABS) prepared via bulk polymerization Depending on the molecular weight (Mw) of styrene-acrylonitrile copolymer (SAN) have been investigated.The tenDencies of attaining the yield stress at steady-state shear flow and approaching to the .plateau. region of storage modulus at low frequencies in oscillatory tests were observed. Both these phenomena are induced by formation of the structural skeleton consisting of polybutadiene (PB) particles arranged in the SAN-matrix. Growth of Mw of SAN leads both to increase of the .plateau. value of storage modulus at low frequencies and the yield stress.This fact can be explained by the influence of Mw of SAN chains grafted onto PB particles on structure formation in ABS melts because of a redistribution of the ratio particleparticle / particle-matrix interactions. The elongational viscosity of ABS melts is a power function of Mw of SAN matrix. The power inDex of this function increases with the polymer straining that reflects orientation of SAN chains with their length increase. The strain-harDening inDex of ABS melts increases consiDerably with increase of SAN matrix Mw. However, it does not Depend on presence of PB particles in the material. It means that the value of this inDex is governed by orientation effect in the SAN matrix.The impact strength of the investigated ABS samples is interrelated with rheological characteristics of ABS melts as well as Mw of SAN. The DepenDence of impact strength on Mw can be explained by increasing role of orientation effects of SAN chains with Mw increase in the copolymer fibrils connecting the walls of crazes formed at impact action.► Cite this publication as follows:
Dreval VE, Vasilev G, Borisenkova E, Semakov A, Kulichikhin VG: Influence of Molecular Weight of SAN on Rheological and Mechanical Properties of ABS-plastics, Appl. Rheol. 17 (2007) 44745.
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.
ConsiDeration is given to the reaction to Barnes and Walters' 4-page The yield stress myth? paper published 21 years ago. It has been cited approximately 180 times since then, as either a standard reference for 'yield stress' papers, or to disagree with its sentiment that yield stresses do not actually exist, but are a useful approximation. The references that cite the paper are categorized and commented on.► Cite this publication as follows:
Barnes HA: The 'Yield stress myth?' paper - 21 years on, Appl. Rheol. 17 (2007) 43110.
The concentration and size DepenDencies of elastic properties of highly concentrated w/o emulsions were studied. The range of weight concentration of the disperse phase was 90 - 96%, the range of the average droplet size was 16 - 20 μm, and the droplet size distribution remained unchanged. The disperse phase consists of droplets of over-cooled concentrated aqueous solutions of inorganic salts. The concentration range being studied lies above the limit of maximal close packing, φ > φm. The droplet size distribution is fairly wiDe and the shape of droplets is polygonal.These factors alone Determine possible new rheological effects, such as the elasticity and visco-plastic behaviour of emulsions, as well as the observed form of concentration and size DepenDencies of rheological properties of emulsions. The complete flow curves were measured for these fairly new emulsion systems. It emerged that they were similar to the entire concentration and droplet size ranges being studied. The concentration DepenDencies of the yield stress and storage modules corresponDed to the Princen-Kiss theory with critical volume concentration approximately 0.71 - 0.74. However, this theory Describes the size DepenDence of elastic modules incorrectly. A new moDel is proposed, which correctly Describes the DepenDencies of elastic modules on both Determining parameters - those of concentration and droplet size.► Cite this publication as follows:
Masalova I, Malkin AY: Rheology of highly concentrated emulsions - concentration and droplet size dependencies, Appl. Rheol. 17 (2007) 42250.
► Cite this publication as follows:
Miller R, Schaffler M: User Seminar of 2D and 3D Rheology of Fluid Systems, Appl. Rheol. 17 (2007) 164.
This paper presents a characterization of the following dry granular materials: soya, colza and rye seeds. The physical properties of the grains and the materials are useful for characterizing the materials behaviour during flow, while the external conditions (consolidation) Determine storage and handling conditions. The physical properties of the grains (specific Densities) and of the materials as a whole (compacity or porosity, and critical angles) were measured. The flow functions were Determined by modified shear box testing. Then the internal friction angles and the flowability inDex for each granular material were obtained. InDeed, the behaviour of a flowing granular material results from these two groups of factors and is characterized by the flowability, which is the ratio of highest consolidation stress and unconfined yield strength. In practice, the flowability inDex is used to classify materials, so that the larger the flowability inDex, the smaller the bulk solids strength will be in relation to the consolidation stress, and therefore the higher the flowability of the bulk solid.► Cite this publication as follows:
Degouet C, Nsom B, Lolive E, Grohens A: Characterization of wood granules, soya, colza and rye seeds, Appl. Rheol. 17 (2007) 36546.
The effects of free surface shape on normal stress difference measurements 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.
Pre-thickened beverages and barium sulfate suspensions are used in the treatment and diagnosis of dysphagia. These liquids are labeled nectar consistency (NC), honey consistency (HC) etc.These labels are rather misleading and do not represent the actual rheological character of the liquids.We carefully investigated the rheology of these liquids to assist both in their formulation and use for dysphagic patients. Steady state flow properties, thixotropy, dynamic response, and creep recovery behavior were investigated for six beverages and two barium sulfate suspensions. All samples exhibited a shear-thinning behavior. The flow curves of all samples followed both Herschel-Bulkley and Casson moDels. HC barium sulfate suspension exhibited higher yield stress, σ0, and higher storage modulus, G', than their fluid food counterparts. In contrast, NC barium sulfate suspension had lower σ0, and G' than some of the liquid food counterparts. Frequency spectra of NC samples were similar to that of a macromolecular solution with both G' and loss modulus, G'', increasing with frequency; whereas those of HC samples were similar to that of a gel with a little DepenDency of G' and G'' over frequency. Stress sweep experiments showed that the linear viscoelastic region of fluid foods and barium sulfate suspensions extenDed up to 1 and 10 Pa, respectively. Thus, significant differences exist in the rheological properties of both pre-thickened and viDeofluoroscopy fluids currently used for diagnosis and treatment of dysphagia.► Cite this publication as follows:
OuldEleya MM, Gunasekaran S: Rheology of fluid foods for dysphagic patients, Appl. Rheol. 17 (2007) 33137.
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.
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 requirements. In this paper, we revisit some moDel reduction techniques recently 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.
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.
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 presented 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 rheological behaviour of frozen soils Depends on a number of factors and is complex. Stress and temperature histories as well as the actual composition of the frozen soil are only some aspects that have to be consiDered when analysing the mechanical response. Recent improvements in measuring methods for laboratory investigations as well as new theoretical moDels have assisted in Developing an improved unDerstanding of the thermo-mechanical processes at play within frozen soils and representation of their response to a range of perturbations. This review summarises earlier work and the current state of knowledge in the field of frozen soil research. Further, it presents basic concepts as well as current research gaps. Suggestions for future research in the field of frozen soil mechanics are also maDe. The goal of the review is to heighten awareness of the complexity of processes interacting within frozen soils and the need to unDerstand this complexity when Developing moDels for representing this behaviour.► Cite this publication as follows:
Arenson LU, Springman SM, Sego DC: The Rheology of Frozen Soils, Appl. Rheol. 17 (2007) 12147.
Rheology is commonly used as a tool for analytics and quality control in latex technology. As soon as flow becomes essential for the structure measured in a scattering experiment we call it scattering from shear-orDered dispersions or rheologic scattering. In this paper it is shown that the structure of concentrated dispersions can with advantage be studied by scattering experiments. Theoretical and experimental aspects as well as examples of small-angle synchrotron x-ray and neutron scattering from colloidal dispersions, presented in the paper, are closely related to rheology.► Cite this publication as follows:
Versmold H: Scattering from shear-ordered dispersions, Appl. Rheol. 17 (2007) 11412.
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.
► Cite this publication as follows:
Rheological Societies: Society's Site March 2007 - August 2007, Appl. Rheol. 17 (2007) 52.
► Cite this publication as follows:
Wagner C: Microrheology and Rheological Phenomena in Microfluidics 2006 Workshop of the German Rheological Society (DRG) , Appl. Rheol. 17 (2007) 42.Peter Fischer and Martin Kroger
Patents Review (December 2006)
Appl. Rheol. 16:6 (2006) 343-344 ►
► Cite this publication as follows:
Fischer P, Kroger M: Patents Review (December 2006), Appl. Rheol. 16 (2006) 343.
► Cite this publication as follows:
Shaqfeh ESG, Prakash R: Report on the International Workshop on Mesoscale and Multiscale Description of Complex Fluids, Appl. Rheol. 16 (2006) 340.
In this paper, by means of Advanced Rheometric ExpanDed System (ARES), oscillatory and steady shear behavior of binary mixtures of a quaternary ammonium based ionic liquid [Me3NC2H4OH]+[Zn2Cl5]- with ethanol (EtOH) were Determined at 25 C and 25-50 C, respectively. The effects of shear rate, temperature and concentration on viscosity were elucidated sufficiently. It was found that the solutions show pseudo-plastic behavior at low shear rate and Newtonian property at higher shear rate. The addition of EtOH caused a substantial Decrease in viscosity of the ionic liquid and the viscosity of binary mixtures could be Described by an exponential equation. Arrhenius Equation and Power Law equation were applied to Describe the respective effects of temperature and shear rate on viscosity. Activation energy Derived from Arrhenius equation Decreased with increasing the EtOH fraction in the mixture.► Cite this publication as follows:
Li Q, Wu G, Liu Y, Luo Y: A rheological study of binary mixtures of Ionic Liquid [Me3NC2H4OH]+[Zn2Cl5]- and ethanol, Appl. Rheol. 16 (2006) 334.
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.
In Couette rheometry, most of the current flow-curve recovery algorithms require the explicit numerical differentiation of the measured angular velocity data. The exceptions and popular choices, because it avoids the need for a numerical differentiation, are the parallel plate approximation (cf. Bird et al. [1], Table 10.2-1) and the simplest of the formulas given in Krieger and Elrod [2]. However, their applicability is limited to narrow gap rheometer data. In this paper, equally simple formulas are presented which are exact for Newtonian fluids, do not involve a numerical differentiation and are consistently more accurate than the simple formulas mentioned above. They are based on a generalization of the Euler-Maclaurin sum formula solution of the Couette viscometry equation given in Krieger and Elrod. As well as illustrating the improved accuracy for the recovery of flow-curves for fluids with and without a yield-stress, Details about more general and accurate formulas for flow-curve recovery from Couette rheometry data are given. The situation for the recovery of flow-curves from wiDe gap rheometery measurements is also discussed.► Cite this publication as follows:
deHoog F, Anderssen R: Simple and Accurate Formulas for Flow-Curve Recovery from Couette Rheometer Data, Appl. Rheol. 16 (2006) 321.
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. ...► Cite this publication as follows:
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.
We proviDe an overview of transient extensional rheometry techniques for wheat flour doughs in which the Deformation and material response is well Defined. The behavior of a range of moDel doughs was explored with a Filament Stretching Extensional Rheometer (FISER). The measurements were also compared to data obtained with a new windup extensional rheometer; the SER universal testing platform. A simple empirical constitutive equation, which allows characterization of the experimental results with a small number of parameters, is presented to Describe the resulting measurements. To characterize the relaxation modulus of the doughs, small amplituDe shear tests were performed on samples that have been shear-mixed in a mixograph for varying lengths of time. The linear viscoelastic properties were found to exhibit a broad power-law DepenDence on the imposed oscillatory frequency that is very reminiscent of that exhibited by a critical gel. The critical gel moDel of Winter and Chambon was used as the basis for constructing a non-linear constitutive equation for the material stress by combining the relaxation modulus for the critical gel with a Lodge rubber-like liquid form for the kinematics. Transient uniaxial extensional data recorDed from the FISER and SER instruments were then compared to the predictions of the constitutive equation. The moDel captures the initial powerlaw response and subsequent strain-harDening; however additional physics is required to Describe the rheological phenomena at very large Hencky strains, including finite extensibility effects and filament rupture in extensional flows.► Cite this publication as follows:
Ng TS, McKinley GH, Padmanabhan M: Linear to Non-linear Rheology of Wheat Flour Dough, Appl. Rheol. 16 (2006) 265.
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 W, Fryer P: 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.
► Cite this publication as follows:
Rheological Societies: Society's Site September 2006 - February 2007, Appl. Rheol. 16 (2006) 220.
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.
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 (reverse 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, Nicoterra 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.
Blends of 30-phr silica filled elastomeric chlorinated polyethylene (CPE) and natural rubber (NR) at the blend composition ratio of 80/20 CPE/NR were prepared with various mixing time from 120 to 600 s. Viscoelastic behaviours of cured and uncured blends were Determined using two rheometers with different shear moDes, i.e., the oscillatory rheometer (Rubber Process Analyser, RPA2000) and the rate-controlled capillary rheometer (Goettfert Rheotester 2000). Results obtained reveal that the viscoelastic behaviour of blends is influenced by the formation of silica transient network, particularly in cured blends. Mixing time affects viscoelastic properties of vulcanised blends to some extent which is due probably to the high extent of thermal Degradation, but plays no significant role in viscoelastic properties of unvulcanised blends. The superimposition of oscillatory and steady shear results is possible when the elastic component is eliminated from the results.► Cite this publication as follows:
Phewthongin N, Saeoui P, Sirisinha C: Comparison of Viscoelastic Behaviour in Silica Filled Cured and Uncured cpe/nr Blends with Various Mixing Time, Appl. Rheol. 16 (2006) 182.
► Cite this publication as follows:
Schweizer T: Einfluss von Dehnströmungen auf die Morphologieausbildung in Polymerblends / Influence of Elongational Flows on the Morphology Evolution of Polymer Blends (M. Heindl), Appl. Rheol. 16 (2006) 131.
Liquid crystalline polymer (LCP) and polyethylene terephthalate (PET) were blenDed in an elastic melt extruDer to make samples having different volume fractions of constituent polymers. Shear stress, shear viscosity, first normal stress difference at different shear rates unDer steady state conditions of these blends were evaluated at two different temperatures 265 and 285°C. The LCP was in solid state at 265° C and in melt state at 285°C and was dispersed in molten matrix of PET at both temperatures. Shear viscosity of blend increased with addition of LCP in PET matrix. A maxima was observed in viscosity versus composition plot. Blends containing more than 50 vol. % of LCP in the blend show higher viscosity as compared to the constituent polymers. First normal stress difference, N1, increased with LCP content in the blend at 285°C when ploted against shear stress whereas at 265°C this trend was opposite. The increased value of N1 with shear rate was explained assuming a tenDency of asymmetric particles to rotate unDer velocity gradient of suspending medium. At 285°C N1 varied with shear stress in two stages. First stage was characterized with high sensitivity of N1 with shear stress, which reduced in second stage on plastic Deformation of LCP droplets.► Cite this publication as follows:
Hashmi SAR, Kitano T: Rheology of LCP/PET Blends at Solid and Molten States of LCP, Appl. Rheol. 16 (2006) 152.
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.► Cite this publication as follows:
Laine C, Cassagnau P: Prediction of Zero Shear Viscosity of Poly (Vinyl Chloride) Plastisols, Appl. Rheol. 16 (2006) 136.
We present a simple methodology for extending linear viscoelastic measurements of crystallizing polymers tothe high-frequency regime, where usually crystallization kinetics represents an obstacle. The iDea is to performrapid quenches, below the melting temperature (which corresponds to the high-frequency region), account forthe thermal equilibration and the very slow early stages of crystallization, and perform the measurements beforereally crystallization sets in, in the 'quasi-equilibrium' state. Albeit tedious, when properly done, this methodworks remarkably well, as Demonstrated for a particular polybutadiene mixture, and opens the route for obtain-ing rheological master curves in a wiDe variety of crystallizing polymers.► Cite this publication as follows:
Kapnistos M, Vlassopoulos D: Rheological Master Curves of Crystallizing Polymer Mixtures, Appl. Rheol. 16 (2006) 132.
► Cite this publication as follows:
Handge UA, Sailer C: Disperse Polymer Systems, Dresden/Germany, Appl. Rheol. 16 (2006) 161.
This paper attempts to investigate the problem for the interaction between a screw dislocation and a piezoelectric circular inhomogeneity with interface cracks in viscoelastic matrix. Utilizing the Laplace transform method, we find that the viscoelastic problem is first reduced to an associated elastic one. After solving the associated elastic problem through complex function method, the solution of viscoelastic problem is obtained by using the inverse Laplace transformation. The viscoelasticity of material is moDeled by the combination of spring and dashpot. Particularly, the boundary value problem for standard linear solid moDel is solved analytically. The analytical results show that the force acting on the dislocation Depends on the piezoelectric properties of inhomogeneity and interfacial crack, and the magnituDe of the force evolves toward a constant value as time elapses. However, the viscoelasticity of material cannot alter the equilibrium position of the dislocation. Results presented in this paper are in agreement with the previous solution as special cases.► Cite this publication as follows:
Liu Y, Li B, Fang Q: Interaction Between a Screw Dislocation and a Piezoelectric Circular Inhomogeneity with Interfacial Cracks in Viscoelastic Matrix, Appl. Rheol. 16 (2006) 102.
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.
This paper is concerned with a fuzzy moDel Developed for Describing the rheological properties of lime pastes and mortars. We have iDentified the physical parameters on which the flow properties of these materials Depend, and whose complex interrelationships make it difficult to moDel the phenomena using a traditional approach. The basic notions of fuzzy moDelling are Described, a technique which enables different kinds of variables and other knowledge elements to be handled in a formal context that can be easily computerized. Applying the Fuzzy Approximation Theorem we can Develop a moDel irrespective of whether the correlation functions are expressed in explicit analytical form or not. The Definitions of the fuzzy sets for the different variables are proviDed which, together with IF/THEN rules comprise the knowledge base of the moDel. The moDel is then applied to Determine the plasticity of lime pastes and consistency of lime-based mortars using ordinary fuzzy inference mechanisms.► Cite this publication as follows:
Atzeni C, Sanna U, Spanu N: A Rheological Fuzzy Model for Lime Plasticity and Mortar Consistency, Appl. Rheol. 16 (2006) 80.
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.
► Cite this publication as follows:
Ilg P: Models for polymeric and anisotropic liquids (M. Kröger), Appl. Rheol. 16 (2006) 12.
Rheological properties of food fluids are useful for quality control, texture evaluation, and food structure Determination. The rheological behavior is DepenDent on the size, form and concentration of solids in suspension and the system structure. Star fruit (Averrhoa carambola L.) pulp was obtained from the cruDe fruit and treated enzymatically, pasteurized and homogenized at 11000 rpm for 2 min and 22000 rpm for 5 min. The pulp presented Newtonian characteristics with R2 values greater than 0.98. Enzymatic treatment unDer 55 C for 1 h reduced the cruDe pulp viscosity from 1.84 to 1.22 mPa.s. Pasteurization unDer 100 C for 10 min increased the viscosity at around 26% in relation to the cruDe pulp, resulting in a turbid and homogeneous product. To evaluate the influence of the insoluble solids, filtration or concentration to 50% from the initial volume were carried out using laboratory procedures. Filtration of the pasteurized pulp promoted a viscosity Decrease of 60% while concentration increased the viscosity from 2.28 to 7.98 mPa.s► Cite this publication as follows:
Vendrusculo AT, Hotza D, Gomes CM, Quadri MGN: Rheology of Star Fruit Pulp (Averrhoa Carambola L.), Appl. Rheol. 16 (2006) 26.
Conventional methods often impose difficulties when measuring the viscosity of fluids containing particles or fibres, e.g. tomato paste or fruit preparations, mainly due to the narrow gaps of the viscometer. In orDer to solve these problems different geometries have been Developed, e.g. different mixer systems and wiDe gap double concentric cylinDers. However, these can not be evaluated assuming a constant shear rate throughout the fluid. In this study, three different kinds of mixer systems have been studied; a small and a large paddle and a helix. For the mixer systems an average shear rate must be Determined and a quotient between torque and shear stress must be found. In addition, a wiDe gap double concentric cylinDer (DCC) was examined and evaluated using two different methods. When evaluating the mixer systems a method based on the Couette analogy has been used successfully for a number of complex fluids, including prepared sauces and fruit samples containing particles of different size. The DCC has been evaluated using a numerical as well as an approximate method, both giving results of good accuracy. All systems had the limitation that no consistent results were obtained for tomato paste. However, when starch was adDed to the diluted tomato paste dispersion, satisfying results were once again obtained.► Cite this publication as follows:
Roos H, Bolmstedt U, Axelsson A: Evaluation of New Methods and Measuring Systems for Characterisation of Flow Behaviour of Complex Foods, Appl. Rheol. 16 (2006) 19.
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-Gonzales 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.
The main aim of the work is to study the physicochemical and rheological behaviour of agar gel extracted from a red seaweed Gelidiella acerosa collected from various locations and seasons in southeast coast and west coast of India. The thesis also Deals with the rheological studies of agar gels in presence of various additives including surfactants and fatty acids as well as agar and carrageenan based film-forming dispersions. The observed shear viscosity values were correlated with existing rheological moDels. It was observed from the shear viscosity studies that agar gel become more gel thinning in presence of non ionic surfactants as well as in presence of fatty acids. Oscillation sweep measurements revealed that the agar gel become liquid like in presence of nonionic surfactants and opposite is true in presence of ionic surfactants. The film forming dispersions prepared from agar and plasticizers had inferior rheological behaviour in comparison to k-carrageenan based thin film forming dispersions. All the agar gel samples collected from various locations displayed different rheological behaviours.► Cite this publication as follows:
Prasad K: Chemical and Rheological Studies on Seaweed Polysaccharides (PhD Thesis), Appl. Rheol. 16 (2006) 32.
► Cite this publication as follows:
Rheological Societies: Society's Site March 2006 - August 2006, Appl. Rheol. 16 (2006) 46.
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.► Cite this publication as follows:
Sato J, Breedveld V: Evaporation Blocker for Cone-Plate Rheometry of Volatile Samples, Appl. Rheol. 15 (2005) 390.
We present a one-parameter moDel that fits quantitatively the mean velocity profiles from experiments and numerical simulations of drag-reduced wall-bounDed flows of dilute solutions of polymers and non-Brownian fibers in the low and moDest drag reduction regime. The moDel is based on a viscous mechanism of drag reduction, in which either extenDed polymers or non-Brownian fibers increase the extensional viscosity of the fluid and thereby suppress both small and large turbulent eddies and reduce momentum transfer to the wall, resulting in drag reduction. Our moDel proviDes a rheological interpretation of the upward parallel shift S+ in the mean velocity profile upon addition of polymer, observed by Virk. We show that Virk's correlations for the DepenDence on polymer molecular weight and concentration of the onset wall shear stress and slope increment on the Prandtl-Karman plot can be translated to two dimensionless numbers, namely an onset Weissenberg number and an asymptotic Trouton ratio of maximum extensional viscosity to zero-shear viscosity. We believe that our moDel, while simple, captures the essential features of drag reduction that are universal to flexible polymers and fibers, and, unlike the Virk phenomenology, can easily be extenDed to flows with inhomogeneous polymer or fiber concentration fields.Corrigendum for this article >>
► Cite this publication as follows:
Roy A, Larson RG: A Mean Flow Model for Polymer and Fiber Turbulent Drag Reduction, Appl. Rheol. 15 (2005) 370.Peter Fischer and Martin Kroger
Patents Review (December 2005)
Appl. Rheol. 15:6 (2005) 414 ►
► Cite this publication as follows:
Fischer P, Kroger M: Patents Review (December 2005), Appl. Rheol. 15 (2005) 414.
The rheological behaviour of a cement paste used in Self-Compacting Concretes (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 concretes, 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.
The propagation of ultrasonic waves in polymers Depends on their viscoelastic behaviour and Density, resulting significantly affected by phase transitions occurring with changing temperature and pressure or during chemical reactions. Therefore, the application of low intensity ultrasound, acting as a high frequency dynamic mechanical Deformation applied to a polymer, can monitor the changes of viscoelastic properties associated with the glass transition, the crystallization, the physical or chemical gelation, the crosslinking. Thanks to the non-Destructive character (due to the very small Deformation amplituDe), low intensity ultrasound can be successfully used for polymer characterization. Moreover, this technique has a big potential as a sensor for on-line and in-situ monitoring of production processes for polymers or polymer matrix composites. Recently, in the laboratory of Polymeric Materials of Lecce University a custom maDe ultrasonic set-up for the characterization of polymeric material, even at high temperatures, has been Developed. The ultrasonic equipment is coupled with a rotational rheometer. Ultrasonic waves and shear oscillations at low frequency can be applied simultaneously on the sample, getting information on its viscoelastic behaviour over a wiDe frequency range. The aim of this paper is to present the potential and reliability of the ultrasonic equipment for the ultrasonic dynamic mechanical analysis (UDMA) of both thermosetting and thermoplastic polymers. Three applications of UDMA to different polymeric systems will be reviewed, concerning the cross-linking of a thermosetting resin, the crystallisation from melt of a semicrystalline polymer and the water sorption in a dry hydrogel film. From the ultrasonic velocity and attenuation measurements, the viscoelastic properties of the tested polymers are evaluated in terms of complex longitudinal modulus and compared with the results of conventional dynamic mechanical analysis, carried out at low frequency.► Cite this publication as follows:
Lionetto F, Montagna F, Maffezzoli A: Ultrasonic Dynamic Mechanical Analysis of Polymers, Appl. Rheol. 15 (2005) 326.
Polymer melts can be mixed with many monomers, plasticizers, antistatics or foaming additives. Properties of such mixtures can change during blending because of chemical reactions like polymerization or crosslinking. The process may be carried out either in stirred tanks, extruDers or in motionless mixers. In this paper we focused on the mixing time and the diffusion time of reagent, plasticizer and polymer thanks to rheological tools, and on the way how rheological properties can be studied during chemical reaction in polymer blending. The concept of rheoreactor and Couette analogy were introduced since we have a reactor on our disposal that can mix solution and measure rheological properties without taking sample. This apparatus appears to be an appreciable tool in complement of internal mixers that are specific to polymer blending. For example, we show the importance of the competition between mixing time and reaction time for reactive systems.► Cite this publication as follows:
Lacoste C, Choplin L, Cassagnau P, Michel A: Rheology Innovation in the Study of Mixing Conditions of Polymer Blends during Chemical Reaction, Appl. Rheol. 15 (2005) 314.
► 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.
► Cite this publication as follows:
Kroger M: Understanding the Properties of Matter (Michael Podesta), Appl. Rheol. 15 (2005) 311.
► Cite this publication as follows:
Rheological Societies, Mielke W, Coussot P, Mavrantzas VG, Wagner MH, Zatloukal M: Society's Site September 2005 - February 2006, Appl. Rheol. 15 (2005) 252.
► Cite this publication as follows:
Peters F: CECAM Workshop on Modeling and Simulation of Entangled Polymeric Liquids, Appl. Rheol. 15 (2005) 240.J. Stange
Workshop Rheology and Processing of Polymers
Appl. Rheol. 15:4 (2005) 238-239 ►
► Cite this publication as follows:
Stange J: Workshop Rheology and Processing of Polymers, Appl. Rheol. 15 (2005) 238.
The mechanical properties of the lamellar phase, La, of the system C_12 E_4/D_2O were studied along an isoplethal path (30 wt% C_12 E_4) in the temperature range 10 - 60 C. A dynamic analysis was Determined by small strain oscillatory rheometry. The multilamellar vesicles (MLVs) (onions) were transformed by shearing the lamellar phase. The micellar phase was investigated by steady and dynamic rheological experiments. The micellar aggregate size increases slightly upon heating and the transition from micelles to lamellae appears to be a first orDer transition. The mechanical spectra of the lamellar phase show a strong DepenDence of the moduli on the frequency. This is typical of Defective lamellar phases. They are different from MLVs mechanical spectra. The MLVs viscous and storage moduli are almost inDepenDent from the frequency and they exhibit the characteristics of a strong gel. The temperature of formation of the MLVs phase influences the mechanical properties of the MLVs. Three different packing states of the MLVs phase were observed in the temperature range 25 - 55 C.► Cite this publication as follows:
Coppola L, Nicotera I, Oliviero C: Dynamic Rheological Analysis of MLVs and Lamellar Phases in the System C_12 E_4/D_2O, Appl. Rheol. 15 (2005) 230.
The correlation between the Bostwick Degree and the static rheological properties of yield stress food fuids is first revisited and then reformulated in this work. The role of the yield stress in the free surface flow of the Bostwick test is studied using dimensional analysis. Results from experiments on 48 different samples of yield stress fluids are consiDered and incluDed to check the aDequacy of the proposed correlation. Asymptotic dynamic behaviour is also presented and discussed as a mechanism of complete self similarity with respect of the dimensionless time. This approach would seem to support the opinions in favor of the yield stress as a key parameter, and thus offers an interesting new viewpoint useful to both future experiments on the Bostwick test and studies of 'dam-break' like dynamics.► Cite this publication as follows:
Perona P: Bostwick Degree and Rheological Properties: an Up-to-date Viewpoint, Appl. Rheol. 15 (2005) 218.
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).► 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 representation 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.
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.
► Cite this publication as follows:
Bauer H, Fischle E, Gehm L, Marquardt W, Mezger T, Osterhold M: Modern rheological test methods: Fundamentals and comparative testing programme for the determination of the yield point, Appl. Rheol. 15 (2005) 122.
► Cite this publication as follows:
Rheological Societies, Petrie CJS, Mielke W, Coussot P, Kissi NE, Fischer P, Mavrantzas VG, Grizzuti N, Jarvela P, Wanger MH: Society's Site March 2005 - August 2005 , Appl. Rheol. 15 (2005) 59.
► Cite this publication as follows:
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.► Cite this publication as follows:
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.P. Fischer and M. Kroger
Patents Review (December 2004)
Appl. Rheol. 14:6 (2004) 331-334 ►
► Cite this publication as follows:
Gabriele D, Kroger M: Patents Review (December 2004), Appl. Rheol. 14 (2004) 331.John Truscott
4th Conference on Modelling and Simulation in Medicine
Appl. Rheol. 14:6 (2004) 327 ►
► Cite this publication as follows:
Truscott J: 4th Conference on Modelling and Simulation in Medicine, Appl. Rheol. 14 (2004) 327.
The behaviour of reverse micellar solution and reverse 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 reverse 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 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.
A viscosity function for highly-shear-thinning or yield-stress liquids such as pastes and slurries is proposed. This function is continuous and presents a low shear-rate viscosity plateau, followed by a sharp viscosity drop at a threshold shear stress value (yield stress), and a subsequent power-law region. The equation was fitted to data for Carbopol aqueous solutions at two different concentrations, a drilling fluid, an water/oil emulsion, a commercial mayonnaise, and a paper coating formulation. The quality of the fittings was generally good.► Cite this publication as follows:
Mendes PRS, Dutra ESS: Viscosity Function for Yield-Stress Liquids, Appl. Rheol. 14 (2004) 296.
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 measurements 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 Determination of flow curves and the apparent viscosity curves at 28°C of creams containing human leukocyte alpha interferon as active principle is presented in this paper. These creams are used for the treatment of papiloma virus and herpes simplex. It is Demonstrated that their behaviour corresponds to a thixotropic fluid. The Herschel-Bulkley moDel parameters are presented and discussed as an indicator of the graDe of thixotropy. Apparent viscosity plotted as a function of shear rate and storage time allows Defining the time period in which the samples recover their initial structure. Additionally it was concluDed that for Determining the quality of the product, the acceptance limit of the viscosity should be specified for a given shear rate.► Cite this publication as follows:
Zumalacarregui L, Vazquez M, Estevez T, Aguilera A, Hardy E: Rheological Studies of Interferon Creams, Appl. Rheol. 14 (2004) 251.
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.
► Cite this publication as follows:
Rheological Societies, Emri I, Mielke W, Fischer P, Urska FS: Society's Site September 2004 - February 2005 , Appl. Rheol. 14 (2004) 215.
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 measurements can be improved and simplified over the conventional cone-plate technique by using a partitioned plate. For a polystyrene 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 measurements 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.
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.
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, discrete 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 discrete 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:
Kroger M: Ferrofluids: Magnetically Controllable Fluids and Their Applications (Stefan Odenbach), Appl. Rheol. 14 (2004) 178.
A Detailed analysis of the dynamic flow properties of chitosan in solution at different temperatures (25 - 45 C), chitosan concentration (0.5% - 2.0%), solvent type (acetic, lactic, and hydrochloric acid), and ionic strength (0 and 0.2M NaCl) has been unDertaken. The storage modulus, G', loss modulus, G'' and complex viscosity, h* have been Determined over a wiDe range of frequencies and the results are presented using master curves. For the conditions studied, at low frequencies chitosan solutions show a constant complex viscosity which Decreases as frequency increases. Likewise, storage modulus, G' and loss modulus, G'' increase as frequency increases with G'' being always greater than G' indicating that viscous effects are more important than elastic effects. For moDelling the oscillatory-shear results we used the generalized Maxwell moDel. Two empirical equations were used to correlate the data: Cox-Merz rule for viscosity and Laun's rule for primary normal stress difference. Both relations were found to represent our data for the experimental conditions studied.► Cite this publication as follows:
Martinez-Ruvalcaba A, Chornet E, Rodrigue D: Dynamic rheological properties of concentrated Chitosan solutions, Appl. Rheol. 14 (2004) 140.
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.
► Cite this publication as follows:
vonSeggern E: Lackeigenschaften messen und steuern (Meichsner, Mezger, Schröder), Appl. Rheol. 14 (2004) 104.
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 answer to this provocative question is .no.! This is Demonstrated by experiment and analysis for two very different materials . a highly concentrated emulsion and an 8%v/v Kaolin clay suspension. The flow curves of both materials clearly showed a low shear Newtonian asymptote and a pseudoplastic domain. The difference in the accuracy of the fitting equations relates mainly to the low shear rate domain. While the Cross equation is aDequate over the full flow curve, the power law and the Herschel-Bulkley equations are clearly inaDequate for the low shear rate range. These equations as well as the direct numerical method (using the Rabinowitsch- Weissenberg integral) were used for the calculation of the laminar pipe flow transport characteristics and the results were compared with experimental pipe flow data. It was shown that in all cases the maximum error did not exceed 5%, which is quite acceptable for engineering Design, indicating that the choice of the flow curve fitting equation was unimportant.► Cite this publication as follows:
Malkin AY, Masalova I, Pavlovski D, Slatter P: Is the Choice of Flow Curve Fitting Equation Crucial for the Estimation of Pumping Characteristics?, Appl. Rheol. 14 (2004) 89.
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.Walter Richtering
Condensed Matter Physics (Gert Strobl)
Appl. Rheol. 14:2 (2004) 81 ►
► Cite this publication as follows:
Richtering W: Condensed Matter Physics (Gert Strobl), Appl. Rheol. 14 (2004) 81.
► Cite this publication as follows:
Rheological Societies, Emri I, Mielke W, Fischer P, Boudouvis A, Dupuis D: Society's Site March 2004 - August 2004 , Appl. Rheol. 14 (2004) 55.Dr. J.H. Watson
The Diabolical Case of the Recurring Yield Stress
Appl. Rheol. 14:1 (2004) 40-45 ►
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!► Cite this publication as follows:
Watson JH: The Diabolical Case of the Recurring Yield Stress, Appl. Rheol. 14 (2004) 40.
A creeping squeeze flow apparatus [1 - 2] was modified with a Fizeau interferometer optical motion transducer and equipped with a high-temperature, high-vacuum enclosure. Long-term squeeze flow experiments were done on a broad-MW, 1 melt-flow inDex commercial HDPE at 190.C, with runs covering about a week. Over this period, no thermal Degradation of the polymer was observed, and the geometry of the apparatus was stable. Low-shear-rate viscosities were measured within the maximum shear rates from 1.7 ¥ 10-5 to 7.6 ¥ 10-5 1/s (stress ~ 1.7 to 8 Pa), resulting in an two-DecaDe expansion in the experimental window for this difficult-to-characterize HDPE resin with long relaxation times.► Cite this publication as follows:
Cua EC, Shaw MT: Creeping Sphere-Plane Squeeze Flow to Determine the Zero-Shear-Rate viscosity of HDPE Melts, Appl. Rheol. 14 (2004) 33.
A short synopsis of the recently proposed reptation moDels based on the Doi and Edwards. tube concept is proviDed. Specifically, a critical examination of a number of theories like the .simplified. Mead-Larson-Doi moDel, the Ötinger moDel and the .Double Convection Reptation. moDel of Marrucci and coworkers has been performed. These moDels have been chosen due the fact that are computationally tractable as they mimic the chain dynamics in the tube using unconnected portions of the chain in a mean field way. Overall, we find each of these moDels to be equally competitive barring a few exceptional cases, where it is suspected that certain critical assumptions, maDe during the formulation of the moDel could lead to inaccurate predictions unDer transient or Lagrangian unsteady settings.► Cite this publication as follows:
Gigras PG, Khomami B: An Evaluation of Single-Segment Reptation Theories for Linear Entangled Polymeric Systems, Appl. Rheol. 14 (2004) 22.
It is shown that the combined use of a mesoscopic lattice Boltzmann solver with finite-volume techniques, both enriched with local-refinement (multiscale) capabilities, permits to Describe transport phenomena at fluid-solid interfaces to a Degree of Detail which may help dispensing with empirical correlations.► Cite this publication as follows:
Rotondi R, Succi S, Bella G: Direct Simulation of Fluid Transport at Solid Interfaces with a Multiscale Lattice-Boltzmann Finite-Volume Method, Appl. Rheol. 14 (2004) 12.
► Cite this publication as follows:
VanPuyvelde P, Moldenaers P: Sunny Rheology School in Leuven, Appl. Rheol. 13 (2003) 317.
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.
The effects of composition and resulting morphology on the rheology of thermoplastics filled with different talc platelets were studied in the 0-22% range of volume fraction, F. The sufficiently filled polymer composites exhibit a rheological behavior which significantly differs from the pure polymers used in this work, a linear low Density polyethylene, a low Density polyethylene and a polyamiDe 12. The changes in the rheological behavior are influenced by the size, the concentration and the surface treatment of plate-like talc particles. They also Depend on the chemical nature and viscous and elastic characteristics of the polymer matrix. In particular, the effect of platelet orientation on the viscoelastic properties of reinforced composites was pointed out. For sufficiently filled systems, a low frequency response indicative of a pseudo solid-like behavior is obtained only during the first frequency sweep. In fact, the low frequency storage modulus, G., is constant. With repeated frequency sweeps, more platelets were aligned in the flow direction, thus the low frequency storage modulus gradually Decreases.► Cite this publication as follows:
Mederic P, Moan M, Klopffer M-H, Saint-Gerard Y: Talc filled thermoplastic composites: Melt rheological properties, Appl. Rheol. 13 (2003) 297.
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.
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.► Cite this publication as follows:
Mä, der H: Rotational Spectroscopy of Diatomic Molecules (John Brown and 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.Christian Friedrich
Understanding Viscoelasticity (N. Phan-Thien)
Appl. Rheol. 13:5 (2003) 240-241 ►
► Cite this publication as follows:
Friedrich C: Understanding Viscoelasticity (N. Phan-Thien), Appl. Rheol. 13 (2003) 240.
► Cite this publication as follows:
Rheological Societies: Society's Site September 2003 - February 2004, Appl. Rheol. 13 (2003) 223.
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.► Cite this publication as follows:
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.► Cite this publication as follows:
Uddin W: Viscoelastic Characterization of Polymer-Modified Asphalt Binders of Pavement Applications, Appl. Rheol. 13 (2003) 191.
Apparent viscosity, ha, and first normal stress coefficient, y1, of six different concentrations of cross-linked waxy maize (CWM), 3.5-5 % w/w, and tapioca, 2.8-4 % w/w, starch dispersions (SDs) showed power law relationships with shear rate, g·, and increased with starch concentration. In both ha and y1, volume fraction of the granules, f, played a more important role than the amylose content of the continuous phase. Slope of ha - g· curves increased mildly with starch concentration, while slope of y1 - g· curves was almost the same for CWM at all concentrations and 4 % tapioca SDs. Values of ha and y1 predicted from dynamic rheological and apparent viscosity data based on the Goddard-Miller moDel were in reasonable agreement with experimental values.► Cite this publication as follows:
Genovese DB, Rao MA: Apparent Viscosity and First Normal Stress of Starch Dispersions: Role of Continuous and Dispersed Phases, and Prediction with the Goddard-Miller Model, Appl. Rheol. 13 (2003) 183.
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.► Cite this publication as follows:
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.► Cite this publication as follows:
Aubry T, Razafinimaro T, Jacinto RS, Bassoulet P: Rheological Properties of a Natural Estuarine Mud, Appl. Rheol. 13 (2003) 142.
In this paper after a presentation of the compression test and its classical references in the rheological literature a behaviour parameter iDentification method is introduced using simple compression tests on concentrated geo-suspensions with a plastic fluid behaviour. The obtained theoretical test response is validated for several materials (natural soils, Kaolin clay .). It is also compared with previous solutions obtained by other authors to show that most existing solutions miss one or more terms. Elements are also given on two types of test response perturbations: the induced heterogeneity in the case of slow tests (consolidation phenomena) and the fragmentation of the outer part of sample (granular paste breakings). Finally, compression test results for a nano silica paste are presented as a example and treated as an application of the test exploitation method.► Cite this publication as follows:
Roussel N, Lano C: Plastic Fluid Flow Parameters Identification Using a Simple Squeezing Test, Appl. Rheol. 13 (2003) 132.
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.► Cite this publication as follows:
Jä, der J, Jä, rnströ, m: 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.► Cite this publication as follows:
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.► Cite this publication as follows:
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.
A fluid dynamic analysis package, PolyFlow, based on the finite element method is used to study the sharkskin phenomenon. A stick-slip mechanism is used as the basis for the simulations. This study is aimed at illustrating how fluctuations in the stress at the exit from the die cause similar fluctuations in the extrudate swell ratio, resembling the sharkskin phenomenon. Such fluctuations in the stress at the exit from the die are produced by implementing a stickslip boundary condition at the die wall, mimicking a mechanism of molecular entanglement/disentanglement at the wall. We use a superposition of stress relaxation/stress growth and a periodic change in extrudate swell governed by the die exit stress level to Depict sharkskin. Three relatively monodisperse polybutadienes were used in this study. The simulated sharkskin time period was found to be in good agreement with experimental findings. We found that the simulated pictures of sharkskin are similar for all three molecular weight samples. A comparison between the simulated sharkskin and experimental results show qualitative resemblance. The main problems preventing us from generating more quantitative sharkskin results mainly resiDe in the moDel limitations in Depicting stress singularity, limitations in mesh Design refinement and the constitutive moDel employed. In spite of these limitations, the qualitative agreement between simulation results and experimental data is good.► Cite this publication as follows:
Nithi-Uthai N, Manas-Zloczower I: Numerical Simulation of Sharkskin Phenomena in Polymer Melts, Appl. Rheol. 13 (2003) 79.
The focus of this paper will be on the moDelling and simulation of contraction flow, with marked aspect ratio b = 6, 9, 12. Two fluid families are consiDered: a glycerol Newtonian solution and carboxy-methyl-cellulose (CMC) solutions which present particular rheological properties. Their shear thinning character are moDelled by a Cross formula over a large scale of shear rates. The elongational properties are taken via a simplified Ericksen moDel into account. Experimental velocity profiles are Determined using the Laser Doppler Anemometry (L.D.A) technique. They are found to be in good agreement with numerical velocity profiles obtained using a finite volume method with extra source terms traducing the particular rheological behaviour proposed here. The simulations allow to Determine the different values of an elongational parameter m3. Then, some numerical results concerning the total energy losses are presented using the usual concept of the equivalent length.► Cite this publication as follows:
Devienne R, Corvisier P, Lyazid A: Flow of Some Carboxymethylcellulose Solutions Through Abrupt Axisymmetric Contractions.Experimental Study and Modelling of Shear Thinning and Elongational Effects, Appl. Rheol. 13 (2003) 70.
► Cite this publication as follows:
DeAngelis E: Plasma and Fluid Turbulence:Theory and Modelling (Akira Yoshizawa), Appl. Rheol. 13 (2003) 69.
► Cite this publication as follows:
Rheological Societies: Society's Site March 2003 - August 2003, Appl. Rheol. 13 (2003) 43.
We present new non-linear data in extension and two different shear histories. These data are used to compare the effectiveness of using exponential shear data and uniaxial extension data to characterise the non-linear response of an industrial LDPE melt with the pom-pom molecular moDel. We concluDe that extension and exponential shear both allow good predictions to be maDe in simple shear. However, the characterisation spectrum obtained from exponential shear data fails to predict the correct Degree of strain harDening at low extension rates. From this study we are able to suggest circumstances unDer which exponential shear proviDes a useful characterisation of branched polymer melts.► Cite this publication as follows:
Suneel , Graham RS, McLeish TCB: Characterisation of an Industrial Polymer Melt Through either Uniaxial Extension or Exponential Shear Data: An Application of the Pom-Pom Model, Appl. Rheol. 13 (2003) 19.
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.► Cite this publication as follows:
Beckmann S, Niemeyer J: Flow Patterns of Polymer Solutions Injected into Dispersions of Bentonite, Appl. Rheol. 13 (2003) 14.
A mathematical moDel for the transient pressure response in a capillary rheometer is implemented and validated with experimental data for both a natural rubber compound and a silicone rubber compound. The pressure Decay curve after the cessation of motion of the instrument piston is shown to be consistent with the extrapolation of the power law moDel to shear rates two DecaDes lower than experimentally attainable in the instrument employed. The moDel is useful for extending the range of the instrument in question by approximating material properties at shear rates lower than attainable in a steady flow experiment.► Cite this publication as follows:
Warley R: Modeling the Pressure Decay Cure of a Capillary Rheometer, Appl. Rheol. 13 (2003) 8.
► Cite this publication as follows:
Konietzky H: 1st International PFC-Symposium on Numerical Modeling in Micromechanics via Particle Methods, Appl. Rheol. 12 (2002) 314.
► Cite this publication as follows:
DeCesare G: Third International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering (3rd ISUD), Appl. Rheol. 12 (2002) 309.
The traditional methods of measuring viscosity with rotational viscometers, i.e. cone-plate and concentric cylinDer systems, are often not suitable for suspensions. To be able to measure viscosity on suspensions mixer viscometers have been Developed. In this study a new Design of a helical ribbon impeller has been evaluated and the Metzner-Otto approach has been used to calibrate the impeller. Different kinds of food products were studied. The Metzner-Otto parameter obtained from tomato products was lower than those obtained from starch products. The study showed that the Metzner-Otto parameter varied but seemed rather to be DepenDent on the composition of the food material than on the flow behaviour inDex. The impeller could handle high concentration of quite large particles. This type of helical ribbon impeller viscometer is thus recommenDed for rheological studies of suspensions with high concentration of particles.► Cite this publication as follows:
Ericksson I, Bolmstedt U, Axelsson A: Evaluation of a helical ribbon impeller as a viscosity measuring device for fluid foods with particles, Appl. Rheol. 12 (2002) 303.
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.► Cite this publication as follows:
Hadjistamov D: Viscoelastic Behavior of Disperse Systems with Silicone Oil and Different Fillers, Appl. Rheol. 12 (2002) 297.
New compounds, called inhibitors, proviDe anti-yellowing effect for mechanical pulps and papers, when adDed to the coating formulation. The rheology of coating mixtures, which contain clay, ground calcium carbonate, starch, latex, inhibitors and other minor additives, affects to a certain extent the final quality of the coated paper. The purpose of this work is to investigate the effect of the total weight charge of inhibitors, when present between coating color ingredients, on the thixotropy and visco-elasticity of the mixture and other rheological properties. We also study the Degree of interaction between inhibitor and coating ingredients using Transmission Electron Microscope (TEM) and water retention measurements. For the industrially preferred inhibitor system of low RS/UVA ratio and high total charge the coating formulation will have a significant increase in the general value of viscosity and a clear and profound shear-thinning behavior. UnDer the Desired conditions of higher total charge the coating formulation acquires significant thixotropic behavior. A higher level of energy is required to coat such formulation. The elastic modulus increases with frequency. This rise in the elastic modulus reveals the increasing interaction between particles in the coating formulation. The total charge does not affect the resistance of a coating color to the applied stress. The coating color with low total charge has the strongest water holding capability Decreasing with increasing total charge.► Cite this publication as follows:
El-Sadi H, Esmail N: The Effect of Yellowing Inhibitor Total Charge on The Rheology of Paper Coating, Appl. Rheol. 12 (2002) 289.
Previous studies involving rheological measurement 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 measurements. 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. measurements 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 measurement 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.
PolyFlow, a software package based on the finite element method was employed to simulate the extrudate swell for polybutadiene of various molecular weight (Mw) and molecular weight distribution (MWD). We calculated the relaxation spectra for the different samples and then inserted the spectra into a standard K-BKZ constitutive moDel used in the numerical simulations. Accurate predictions of MWD confirm the completeness of frequency range in the oscillatory shear experimental data. In turn, the wholeness of relaxation spectra as substantiated by MWD predictions, sustain the level of confiDence when using constitutive moDels based on these spectra. We Demonstrate the importance of using the full range of relaxation spectrum rather than a short range around typical shear rates for the accuracy of the numerical predictions. We found extrudate swell ratio (ESR) to be strongly DepenDent on MWD and stress conditions at the die exit.► Cite this publication as follows:
Nithi-Uthai N, Manas-Zloczower I: Numerical Studies of the Effect of Constitutive Model Parameters as Reflecting Polymer Molecular Structure on Extrudate Swell, Appl. Rheol. 12 (2002) 252.
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.► Cite this publication as follows:
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.► Cite this publication as follows:
Bekkour K, Kherfellah N: Linear Viscoelastic Behavior of Bentonite-Water Suspensions, Appl. Rheol. 12 (2002) 234.Walter Richtering
Understanding rheology (F.A. Morrison)
Appl. Rheol. 12:5 (2002) 233 ►
► Cite this publication as follows:
Richtering W: Understanding rheology (F.A. Morrison), Appl. Rheol. 12 (2002) 233.
► Cite this publication as follows:
Rheological Societies: Society's Site Sepember 2002 - February 2003, Appl. Rheol. 12 (2002) 214.
The rheological behaviour of hydrated maize starch is investigated by means of a Haake internal mixer equipped with a sealed chamber. Results were obtained at temperatures between 89 and 115°C with water content between 25 and 30%. Through a proper calibration torque measurements and rotation speeds are converted to shear stress and shear rate data and this leads to the plot of a flow curve in the 10 - 1000 s-1 range. The data are compared with results of capillary rheometer and show that the mixer enables a reproducible plastification of the maize starch. The viscosity of the maize starch in the high shear rate range can be Described by an apparent power law taking into account the moisture and temperature effects. On a larger range of shear rate, a Carreau law is preferred but the DepenDence on the temperature can only be Described with shift factors that require a moisture DepenDent activation energy. Finally, this later discrepancy can be avoiDed by using a reference temperature to fulfil the iso-free volume condition by taking a constant temperature difference towards the glass transition of the samples. The glass transition is calculated by the Couschman and Karasz equation.► Cite this publication as follows:
Brouillet-Fourmann S, Carrot C, Mignard N, Prochazka F: On the Use of an Internal Mixer For the Rheological Characterizattion of Maize Starch, Appl. Rheol. 12 (2002) 192.
A numerical study is conducted on the behaviour of yield stress fluids in a mixing vessel equipped with anchor agitator in laminar regime. It is shown that extending a standard Carreau moDel of shear thinning fluid is a suitable practice. Validations versus Couette flow analytical solution are satisfactory. Main features of local hydrodynamics and global power consumption are Described for a 2D flow. Significant changes in the flow pattern are observed for low inertia and high yield stress and the results are consiDered as guiDelines for further laboratory experiments.► Cite this publication as follows:
Marouche M, Anne-Archard D, Boisson HC: A Numerical Model of Yield Stress Fluid Dynamics in a Mixing Vessel, Appl. Rheol. 12 (2002) 182.
The structural Development unDergoing during the cure of a latex polymer is accompanied by viscoelastic changes, so that this process can be investigated using a rheological approach. We present in this paper the results of a study carried out on one of the most wiDely used chemical binDers in the field of textile nonwovens: acrylic latexes. The rheological measurements have been performed on the latex films in a rectangular torsion and dynamic oscillatory moDe, and the observations are discussed in terms of crosslinking. The results obtained show that the zone where crosslinking occurs in the polymer can be clearly iDentified by the investigation method used.► Cite this publication as follows:
Lewandowski M, Rochery M, Bellayer S, Fourdrin S: Rheology of the Curing Process of Acrylic Latexes Used as Chemical Binders, Appl. Rheol. 12 (2002) 174.
The flow behavior of two commercial liquid crystalline polymers (LCPs), traDe name Vectra B 950 and Vectra L 950 supplied by Ticona, was investigated using a capillary rheometer with a special double slit die. The pressure drops in convergent and divergent wedge passage between the two slit sections, which are influenced by the curvature strains in nematic melts, were Determined and compared with the pressure drops of a conventional polystyrene (PS) with flexible polymer chains. Furthermore the extensional viscositiy was Determined from the pressure drop in convergent wedge passage. The Development of the shear induced texture as a function of shear rate was investigated by use of a rapidly coolable double slit die with the same gap Design as the double slit die used for viscosity measurement. The structural analysis was performed using polarized light microscopy.► Cite this publication as follows:
Nguyen TN, Geiger K, Fritz H-G: Rheological properties and shear induced texture development of thermotopic liquid crystalline polymer melts, Appl. Rheol. 12 (2002) 142.
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.► Cite this publication as follows:
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.► Cite this publication as follows:
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.► Cite this publication as follows:
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.► Cite this publication as follows:
Honek T, Hausnerova B, Saha P: Temperature dependent flow properties of powder injection moulding compounds, Appl. Rheol. 12 (2002) 72.
► Cite this publication as follows:
Rheological Societies, Bouton J, Guerrero A, Young NWG: The Society's Site March 2002 - August 2002 , Appl. Rheol. 12 (2002) 45.
► Cite this publication as follows:
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.► Cite this publication as follows:
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.► Cite this publication as follows:
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.► Cite this publication as follows:
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.► Cite this publication as follows:
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.► Cite this publication as follows:
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.► Cite this publication as follows:
Wand YC, Gunasekaran S, Giacomin AJ: The Lodge Rubberlike Liquid Behavior for Cheese in Large Amplitude Oscillatory Shear, Appl. Rheol. 11 (2001) 312.
► Cite this publication as follows:
Stading M: Das Rheologie-Handbuch - F¨r Anwender von Rotations- und Oszillations-Rheometern (T. Mezger), Appl. Rheol. 11 (2001) 309.
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.► Cite this publication as follows:
Joshi YM: Studies on Wall-Slip in Entangled Polymeric Liquids, Appl. Rheol. 11 (2001) 277.
The Microsoft Excel Solver tool is a very simple but powerful procedure, even in the hands of the mathematically disadvantaged. It has very good application for quickly fitting experimental flow-curve data to non-Newtonian flow moDels with any number of parameters, and can cope with data from a number of sources. Examples are given for a range of industrially important examples ranging from standard non-Newtonian liquids, through Detergent solutions to gels, pastes, and filled polymer melts, often measured on different viscometers.► Cite this publication as follows:
Roberts GP, Barnes HA, Mackie C: Using the Microsoft Excel `solver' tool to perform non-linear curve fitting, using a range of non-Newtonian flow curves as examples, Appl. Rheol. 11 (2001) 271.
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.► Cite this publication as follows:
Junus S, Briggs JL: Vane sensor system in small strain oscillatory testing, Appl. Rheol. 11 (2001) 264.
Dynamic rheological parameters such as storage modulus, G, loss modulus, G, and dynamic viscosity, h, at 200°C were studied for Kevlar fibres, glass fibres and their hybrids reinforced linear low Density polyethylene (LLDPE). Parallel plate rheometer was employed for these tests. G, G and h increased with the increased reinforcement and angular frequency, w. Two sets of reinforcement, 10 and 20 vol.% of fibres are used in LLDPE. The composition of fibres in hybrid composites was varied. The replacement of glass fibres with Kevlar increases the values of G, G and h. The values of these rheological parameters also increased with the thickness of the composite. This increase was associated with the Decreased average orientation of fibres present in the composite. The effects of the change in strain amplituDe on G and G is also studied and reported here.► Cite this publication as follows:
Kitano T, Hashmi SAR, Chand N: Dynamic viscoelastic properties of organic/inorganic fibres reinforced LLDPE composites in molten state, Appl. Rheol. 11 (2001) 258.
► Cite this publication as follows:
Rheological Societies: Society's Site September 2001 - February 2002, Appl. Rheol. 11 (2001) 236.
The rheological behaviour of moDel suspensions with spherical particles was experimentally investigated in shear an elongational flows. Particular attention was focussed on the main parameters affecting the flow behaviour of suspensions such as particle size distribution, particle size, particle surface, humidity, temperature and viscosity of the matrix fluids. All variables were investigated Depending on the pre-shear conditions. In this regard the validity of the time-temperature-superposition and the Trouton-ratio was verified for suspensions with spherical particles.► Cite this publication as follows:
Schmidt M: Rheological properties of suspensions with spherical particles in shear and elongational flows, Appl. Rheol. 11 (2001) 220.
► Cite this publication as follows:
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.
► Cite this publication as follows:
Isaakide G, Frendel A, Bouton J: Product Info: MiniLab - Compounder and Reactor, Appl. Rheol. 11 (2001) 203.
Rheology plays an important role in Dewatering processes. It is therefore interesting to analyze the Dewatering process and the rheological behavior of a suspension simultaneously. An exact Determination of the immobilization point at the maximum of the loss factor as well as the immobilization time can be attained using an oscillatory time test with preset strain. The Degree of Dewatering is Determined via normal force controlled gap setting. This report offers an insight into the theory of the Dewatering of liquid supersaturated suspensions and shows how the kinetics of Dewatering can be Determined using paper coating as an example.► Cite this publication as follows:
Wollny K: New Rheological Test Method to Determine the Dewatering Kinetics of Suspensions, Appl. Rheol. 11 (2001) 197.
The rheological properties of thermotropic liquid crystalline polymer (LCP) and its carbon fiber (CF) and carbon black (CB) filled composites in molten state were measured using a cone-plate rheometer. The measurements of the CF/LCP and CB/LCP melts were performed with carbon fiber contents of 5, 10 and 20 wt %, and carbon black contents of 1.5, 3, 5, 10 and 20 wt %. As expected, steady shear viscosity of the LCP, CF/LCP and CB/LCP melts in a low shear rate region (0.1 to 1 s-1) Decreased with an increase of temperature and increased with rise of filler content. In shear rate region of 1 to 50 s-1, the LCP melt showed a unique viscosity behaviour with maximum and minimum values. The CF/LCP and CB/LCP melts showed disappearance of such a unique viscosity behaviour with an increase in the CF (CB) content and an increase of temperature. CB filler had a more pronounced effect on the disappearance of the unique viscosity behaviour in comparison with CF. Regarding apparent yield stress, the CF/LCP melts gave the same value as pure LCP, the CB/LCP melts showed an increase of yield with a rise of the filler content. In addition, the first normal stress difference of the LCP and CF/LCP melts are smaller than yield stress values, although the rate of increase with shear rate is higher in case of normal stress difference than in case of yield. The results of the dynamic shear oscillatory flow measurements of CF and CB based compounds at 300°C showed that both, the storage and loss moduli are more affected by carbon black filler. Complex viscosity values of the LCP and CF/LCP melts showed no such unique complex flow pattern as observed in the case of steady shear viscosity.► Cite this publication as follows:
Araki K, Kitano T, Hausnerova B: Rheological Properties of Carbon Fiber and Carbon Black Filled Liquid Crystalline Polymer Melts, Appl. Rheol. 11 (2001) 188.
With stress controlled rheometer we investigate the behavior for different concentrations, of paraffin oil-inwater emulsions, bentonite suspensions as well as charged bentonite emulsions. We were particularly interested in how aging affects the rheological properties. Using a structural moDel, we correlate the macroscopic experimental results to the fluid microstructure characteristic parameters and we calculate the emulsions and suspensions mean characteristic unit size. The comparison of these mean particle diameters with those obtained by microscopy and light-scattering measurements confirms the soundness of such procedure to estimate the structural characteristics, the effective concentrations and the effective mean particle diameter of oil-in-water emulsions and bentonite suspensions.► Cite this publication as follows:
Bekkour K, Ern H, Scrivener O: Rheological Characterization of Bentonite Suspensions and Oil-In-Water Emulsions Loaded with Bentonite, Appl. Rheol. 11 (2001) 178.
► Cite this publication as follows:
Mackley M: 3rd Encontro da Sociedade Portuguesa de Rheologia (Mirandela/Portugal), Appl. Rheol. 11 (2001) 155.
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.► Cite this publication as follows:
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.
Eight commercial foods representing a wiDe range of viscosities (i.e. honey, conDensed milk, mayonnaise, tomato ketchup, cream cheese, yogurt, process and Mozzarella cheeses) were investigated. Their steady shear viscosity and dynamic complex viscosity were Determined by rheological measurements at two temperatures using a Bohlin-CVO rheometer. Based on experimental data, shear rate DepenDence of steady flow apparent viscosity and frequency DepenDence of dynamic viscosity was established and compared. It was Determined that for conDensed milk, tomato ketchup and mayonnaise, a modified Cox-Merz relation could be established. For cream cheese, a generalized Cox-Merz relation was proposed; and for yogurt, a Deviation from the Cox-Merz rule was found. For Mozzarella and process cheeses a sharp drop in steady shear viscosity was noticed between 1~10 s-1 shear rate range. The Cox-Merz rule was not applicable for these cheese samples.► Cite this publication as follows:
Yu C, Gunasekaran S: Correlation of dynamic and steady viscosities of food materials, Appl. Rheol. 11 (2001) 134.
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 polystyrene 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.
A frequent task unDertaken by quality-control personnel in typical consumer-goods factories is the measurement of the viscosity of liquid products. The problem often faced in this task is how to strike the correct balance between the complete rheological characterisation of the non-Newtonian properties of the liquid of interest which requires expensive, sophisticated equipment and can be quite time-consuming and the dictates of production pressures that Demand, as near as possible, an instant Decision, and one usually based on a single number. Here we consiDer the rheological issues that arise in such a Debate, which is aimed at finding what aDequate characterisation would require. We will investigate the implications of liquids products being non-Newtonian for two of the most commonly encountered viscometers in factory quality laboratories, i.e. the simple dip-in rotating spindle viscometer of the Brookfield type (with its different forms and many imitations) and the more sophisticated concentriccylinDer- type Device typified by the Haake Rotovisco VT 550 range. Each is capable of giving a single-number answer for viscosity, but the implications of unDerstanding this single number are different in each case, with the dip-in viscometer being in an infinite sea of liquid and the concentric-cylinDer situation being narrow gap. We also investigate when the infinite sea of the dip-in viscometer is effectively infinite and when is a concentric- cylinDer geometry really narrow gap? We will use the power-law moDel throughout our discussions.► Cite this publication as follows:
Barnes HA: An examination of the use of rotational viscometers for the quality control of non-Newtonian liquid products in factories, Appl. Rheol. 11 (2001) 89.
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.► Cite this publication as follows:
Yao ML: Rheological characterization of body lotions, Appl. Rheol. 11 (2001) 83.
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 recent 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 recent 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.
► Cite this publication as follows:
Rheological Societies: Society's Site March 2001 - August 2001, Appl. Rheol. 11 (2001) 45.
► Cite this publication as follows:
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.► 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.
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.► Cite this publication as follows:
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.► Cite this publication as follows:
Adalja SB, Otaigbe JU: Melt rheology of tin phosphate glasses, Appl. Rheol. 11 (2001) 10.Stefan Odenbach
3rd German Ferrofluid workshop
Appl. Rheol. 10:6 (2000) 315-316 ►
► Cite this publication as follows:
Odenbach S: 3rd German Ferrofluid workshop, Appl. Rheol. 10 (2000) 315.
Previous studies have documented the presence of increased red blood cell aggregability in patients with ischemic heart and brain diseases. We adapted a simple sliDe technique and image analysis to reveal the state of erythrocyte adhesiveness/aggregation (EAA) in the peripheral blood of 206 such patients and in 174 controls. A significant (P<0.0001) correlation was noted between the EAA state and both fibrinogen concentrations and erythrocyte sedimentation rate in the whole cohort. Noteworthy was a highly significant increment in the EAA state in a subgroup of 49 patients who had normal fibrinogen concentrations when compared to matched healthy controls. This was also the case in 82 patients who had a normal erythrocyte sedimentation rate. Thus, the EAA assay appears to have the advantage of revealing the presence of acute phase response sticky proteins not Detected by either the erythrocyte sedimentation rate or clottable fibrinogen in some patients with a documented ischemic vascular disease.► Cite this publication as follows:
Zeltser D, Rotstein R, Rogowski O, Fusman R, Shapira I, Prochorov V, Bornstein NM, Roth A, Keren G, Avitzour D, Arber N, Eldor A, Berliner S: The erythrocyte adhesiveness/aggregation test (EAAT) in the peripheral blood of patients with ischemic heart and brain disease with normal fibrogen concentrations, Appl. Rheol. 10 (2000) 231.
► Cite this publication as follows:
Rheological Societies: Society's Site September 2000 - February 2001, Appl. Rheol. 10 (2000) 199.
► Cite this publication as follows:
Anderssen B: Inverse problems and emerging techniques in materials characterization, Appl. Rheol. 10 (2000) 194.S. Odenbach
Magnetoviscous effects in ferrofluids
Appl. Rheol. 10:4 (2000) 178-184 ►
► Cite this publication as follows:
Odenbach S: Magnetoviscous effects in ferrofluids, Appl. Rheol. 10 (2000) 178.
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.► Cite this publication as follows:
Anderson PD, Meijer HEH: Chaotic mixing analyses by distribution matrices, Appl. Rheol. 10 (2000) 119.
► Cite this publication as follows:
Afonso IM, Maia JM: Rheological Monitoring of Structure Development and Rebodying of Set-Style Yoghurt, Appl. Rheol. 10 (2000) 73.
► Cite this publication as follows:
Stranzinger M: Strömungsuntersuchungen mit der Laser-Doppler-Anemometrie bei der Extrusion von Polyethylenschmelzen (Erik Wassner), Appl. Rheol. 10 (2000) 37.
► Cite this publication as follows:
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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Cindio deB: Southern europe conference on rheology (Eurorheo 99-3), Appl. Rheol. 9 (1999) 226.
► Cite this publication as follows:
Weigand J: Viscosity Measurements on Powders with a new Viscometer, Appl. Rheol. 9 (1999) 204.
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Krusteva ED, Radoslavov SY, Diankov ZI: Modelling the Seepage of Groundwater: Application of the Viscous Analogy, Appl. Rheol. 9 (1999) 165.
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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.
► Cite this publication as follows:
Nakajima N: Academic Rheology and Industrial Rheology - A Personal Reflection, Appl. Rheol. 9 (1999) 116.
► Cite this publication as follows:
Barnes HA, Schimanski H, Bell D: 30 Years of Progress in Viscometers and Rheometers, Appl. Rheol. 9 (1999) 69.
► Cite this publication as follows:
Vermant J, Brown ADB, Kroger M: Time resolved evolution of soft condensed matter under flow, Appl. Rheol. 9 (1999) 38.
GENERIC is reviewed not only as a new general framework for moDeling nonequilibrium systems, but also as a new way of thinking about nonequilibrium dynamics. This unified framework of nonequilibrium thermodynamics is shown to be Deeply rooted in the ample accumulated experience with nonequilibrium systems and, proviDe