Jump to Content
View CartTop 20 Most Read Articles
April 2012
The 20 articles with the most full-text downloads during the month, in descending order.
 |
Rheology and microrheology of a microstructured fluid: The gellan gum case J. Rheol. 51, 851 (2007); http://dx.doi.org/10.1122/1.2751385 (15 pages)
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Particle tracking microrheology is used to study the effect of a constant applied shear during gelation of aqueous gellan gum with a monovalent salt. Shear modifies the gellan gum hydrogel microstructure and the bulk rheological properties of the system, depending on whether shear is applied during gelation or afterwards. The microstructure determines the linear elastic response of the gel, as well as the critical strain and stress above which the response becomes nonlinear. Bulk oscillatory rheology is used to study microstructured gellan gum hydrogels at different polymer and salt concentrations. The similarity between our system and concentrated microgel particle suspensions can be explained by considering the microstructured gellan system to be composed of microgel particles whose size is set by the applied shear stress magnitude during gelation. Polymer concentration and ionic strength control the individual microgel particles’ elastic properties. We also find the gellan system exhibits an isoenergetic transition from the jammed to un-jammed state when sheared, similar to jammed colloidal systems [
C. G. Robertson and X. R. Wang, “Isoenergetic jamming transition in particle-filled systems,” Phys. Rev. Lett. 95, 075703 (2005)
].
|
|||
|
Show PACS
|
|||
|
|
Linear and nonlinear rheology of polymer/layered silicate nanocomposites J. Rheol. 54, 539 (2010); http://dx.doi.org/10.1122/1.3372720 (24 pages) Online Publication Date: 07 May 10
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Linear and nonlinear (in both steady and transient shear flows) rheological properties of polymer/layered silicate nanocomposites prepared by melt mixing of poly(butylene succinate-co-adipate) and organically modified montmorillonite are investigated. Morphology of the nanocomposites is observed by x-ray diffraction and by transmission electron microscopy. Linear viscoelastic measurements in oscillatory shear with small strain amplitude show a low frequency plateau for storage modulus (an indication of a pseudo-solid like structure). A strong shear-thinning behavior for all ranges of shear rates is observed for high clay loading. An unusual behavior is observed for steady state normal stress differences. At low shear rates their values are larger than those observed for pure polymer. An inverse relation is observed at relatively high shear rates. The two models [
Eslami, H., M. Grmela, and M. Bousmina, “A mesoscopic rheological model of polymer/layered silicate nanocomposites,” J. Rheol. 51, 1189–1222 (2007)
;
Eslami, H., M. Grmela, and M. Bousmina, “A mesoscopic tube model of polymer/layered silicate nanocomposites,” Rheol. Acta 48, 317–331 (2009)
] that we have developed previously allow us to relate the observed rheological behavior to the physics taking place in the nanocomposites on a mesoscopic level. The models take into account the chain-chain, chain-lamella, and lamella-lamella interactions. With their help, we are also able to separate contributions from the polymer and the nano charge.
|
|||
|
Show PACS
|
|||
|
|
J. Rheol. 56, 333 (2012); http://dx.doi.org/10.1122/1.3684751 (19 pages) Online Publication Date: 01 Mar 12
Full Text:
Read Online (HTML)
|
Download PDF
|
|||||||||||||
|
Show Abstract
Large amplitude oscillatory shear (LAOS) is an increasingly popular nonlinear rheological test method, and the interpretation of the measurements is still an active area of research. Here, we demonstrate a new method whereby the nonlinear parameters of a popular constitutive equation used to model polymeric and other viscoelastic systems, the Giesekus model, may be determined directly from LAOS measurements without complicated, nonlinear model fitting. We define the stress response of the sample as an expansion in deformation strain and oscillation frequency. To leading order in strain, we derive the explicit analytic expressions for the first three harmonics of the stress response during LAOS for the Giesekus constitutive model. This allows for rapid determination of the Giesekus model parameters, including the nonlinear coupling parameter, directly from plots of the response obtained from modern rheological instruments. We demonstrate the validity, utility, and limits of this new method on a well-studied wormlike micelle (WLM) surfactant solution, cetyltrimethylammonium bromide (CTAB), and water. This robust and simple approach is especially advantageous for systems where steady shearing in the nonlinear regime is problematic and can provide rapid determination of parameters in rheological constitutive equations.
|
||||||||||||||
|
Show PACS
|
||||||||||||||
|
|
J. Rheol. 56, 457 (2012); http://dx.doi.org/10.1122/1.3687301 (15 pages) Online Publication Date: 20 Mar 12
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
A comprehensive set of experiments on a two-dimensional constriction flow of a foam are described. Image analysis of the flow is used to ascertain bubble shape and flow dynamics. The bubble velocity, elongation (texture), stress, and deformation rate for a reference case are used to validate a quasistatic simulation. Changes to the constriction geometry, most especially in the rounding of the corners, have a significant effect on the response of the foam, captured in both experiment and simulation. On the other hand, foam properties such as bubble size have little impact on the rheological behavior of the foam in the range considered here.
|
|||
|
Show PACS
|
|||
|
|
J. Rheol. 37, 695 (1993); http://dx.doi.org/10.1122/1.550391 (32 pages)
Full Text:
|
Download PDF
|
||
|
Show Abstract
The properties of aqueous solutions of model HEUR associative thickeners under dynamic and steady shear have been studied as a function of concentration, molecular weight, temperature, and hydrophobic end‐cap length. It is shown that solutions of AT behave as near perfect Maxwell fluids inasmuch that Cole–Cole plots of the dynamic moduli are almost exactly semi‐circular. An Arrhenius law temperature dependence of the static viscosity and relaxation time is also observed, providing confirmation of a single relaxation process. In certain other respects, AT solutions show more complex behavior, e.g., the Cox–Merz rule is not obeyed, with the steady shear viscosity showing a weaker dependence on shear rate than does the complex viscosity upon frequency. Furthermore, weak shear thickening is seen to precede shear thinning in steady shear. The above results are consistent with the predictions of a transient network theory presented recently by Tanaka and Edwards and Jenkins (generalized Green–Tobolsky theory). This does not however explain the strong effect of concentration on the various rheological coefficients. For example, the theory predicts a linear dependence of high‐frequency modulus and static viscosity on concentration, whereas in practice they are found to be more like quadratic and cubic, respectively, at low concentrations. In previous publications this strong dependence has been taken to mean that the network chains are entangled to the point where reptation dynamics determines the time scale of relaxation. This supposition has been tested by mixing solutions of AT with different relaxation times (achieved by means of different end‐cap lengths), on the basis that the mixed solutions should show an intermediate relaxation time if reptation is important. In practice, mixtures of two and three AT were found to show two or three sharp relaxation times, implying that the chains relax independently. It is shown that the true explanation of the strong concentration dependencies is connected with a different kind of change of network topology with concentration. An elementary statistical‐mechanical model, supported by Monte Carlo simulation, is used to argue for a gradual transition from, at low concentrations, micelles built predominantly from looped chains to, at high concentrations, a fully developed network comprising micelles linked by bridging chains. When the transient network theory is modified so as to take the presence of loops into account, it produces results in semiquantitative agreement with experiment. |
|||
|
Show PACS
|
|||
|
|
J. Rheol. 33, 329 (1989); http://dx.doi.org/10.1122/1.550017 (38 pages)
Full Text:
|
Download PDF
|
||
|
Show Abstract
The literature on this subject stands currently at over 100 articles; this review seeks to present an overall picture of the subject, using the results of these articles. Concentrated suspensions of nonaggregating solid particles, if measured in the appropriate shear rate range, will always show (reversible) shear thickening. The actual nature of the shear thickening will depend on the parameters of the suspended phase: phase volume, particle size (distribution), particle shape, as well as those of the suspending phase (viscosity and the details of the deformation, i.e., shear or extensional flow, steady or transient, time and rate of deformation). The explanations offered for the phenomenon that are supported by independent physical measurements postulate that the increase in viscosity is due to the transition from a two‐dimensional layered arrangement of particles to a random three‐dimensional form. The transition rarely takes more than one decade of shear rate, but it can be over a much shorter range, making the increase quite dramatic. These factors of course depend strongly on the particle and fluid parameters. For a suspension of monodisperse spheres suspended in a low viscosity fluid (1–10 mPa⋅s), the onset of shear thickening is very dependent on the sphere diameter, approximately according to an inverse quadratic relationship, with the value for 10 μm spheres being about 0.1 s−1 in steady shear and so on. The severity of the shear thickening depends on the concentration, in proportion to some maximum packing fraction which is itself partly controlled by the form of the particle size distribution. The particle shape is also important. The extent of the phenomenon can be greatly reduced by either reducing the particle size, thus delaying the onset to higher shear rate, or by using a mixture of particle sizes. This latter procedure changes the onset condition, and reduces the severity by increasing the maximum packing fraction of the suspended material. |
|||
|
Show PACS
|
|||
|
|
Shear thickening of cornstarch suspensions J. Rheol. 56, 575 (2012); http://dx.doi.org/10.1122/1.3696875 (17 pages) Online Publication Date: 17 Apr 12
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We study the rheology of cornstarch suspensions, a non-Brownian particle system that exhibits discontinuous shear thickening. Using magnetic resonance imaging (MRI), the local properties of the flow are obtained by the determination of local velocity profiles and concentrations in a Couette cell. For low rotational rates, we observe shear localization characteristic of yield stress fluids. When the overall shear rate is increased, the width of the sheared region increases. The discontinuous shear thickening is found to set in at the end of this shear localization regime when all of the fluid is sheared: the existence of a nonflowing region, thus, seems to prevent or delay shear thickening. Macroscopic observations using different measurement geometries show that the smaller the gap of the shear cell, the lower the shear rate at which shear thickening sets in. We, thus, propose that the discontinuous shear thickening of cornstarch suspensions is a consequence of dilatancy: the system under flow attempts to dilate but instead undergoes a jamming transition, because it is confined. This proposition is confirmed by an independent measurement of the dilation of the suspension as a function of the shear rate. It is also explains the MRI observations: when flow is localized, the nonflowing region plays the role of a “dilatancy reservoir” which allows the material to be sheared without jamming.
|
|||
|
Show PACS
|
|||
|
|
J. Rheol. 56, 1 (2012); http://dx.doi.org/10.1122/1.3662962 (25 pages) Online Publication Date: 29 Nov 11
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
The nonlinear yielding responses of three theoretical models, including the Bingham, a modified Bingham, and Giesekus models, to large-amplitude oscillatory shear are investigated under the framework proposed recently by Rogers et al. (2011). Under this framework, basis states are allowed to wax and wane throughout an oscillation, an approach that conflicts directly with the assumptions of all Fourier-like linear algebraic approaches. More physical yielding descriptions of the nonlinear waveforms are attained by viewing the responses as representing purely elastic to purely viscous sequences of physical processes. These interpretations are compared with, and contrasted with, results obtained from linear algebraic analysis methods: Fourier-transform rheology; and the Chebyshev description of the so-called elastic and viscous stress components σ′ and σ″. Further, we show that the discrepancies between the built-in model responses and parameters, and the interpretations of the Chebyshev and Fourier coefficients are directly related to misinterpretations of σ′ and σ″ as being the elastic and viscous stress contributions. We extend these ideas and discuss how every linear algebraic analysis is likely to conflate information from predominantly elastic and viscous processes when a material yields.
|
|||
|
Show PACS
|
|||
|
|
Deformation and flow of matter: Interrogating the physics of materials using rheological methods J. Rheol. 56, 113 (2012); http://dx.doi.org/10.1122/1.3671401 (46 pages) Online Publication Date: 21 Dec 11
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Rheological measurements offer a unique means of interrogating the physics of amorphous solids, including crosslinked rubbers and polymeric glasses. Here, we present several vignettes to demonstrate the ability of both classical and novel rheological experiments to resolve important questions in condensed matter physics. First, results from torque and normal force measurements aimed at understanding the thermodynamics and mechanics of polymer networks in both dry and swollen states are presented. In particular, we examine the validity of the Frenkel–Flory–Rehner theory of rubber network swelling. Torsion and normal force measurements are also described for a series of polymeric glasses that exhibit similar shear moduli but, surprisingly, very different normal force responses, with one set of materials showing extreme deviations from neo-Hookean behavior and the other being close to neo-Hookean. We then describe the use of a novel torsional dilatometer, which allows simultaneous measurement of mechanical properties and volume recovery, to investigate the aging and rejuvenation behaviors of glassy polymers. Also, the temperature dependence of dynamics is probed in glassy polymers that have been aged into equilibrium below the nominal glass transition temperature and evidence is presented that time-scale divergence may not be a true signature of the glass transition itself. Finally, we describe a reduction in scale of the classical membrane inflation test to allow measurement of the biaxial creep compliance of nanometer thick polymeric films using an atomic force microscope. In each instance, emphasis is placed on how the measurements are designed to interrogate the physics of interest in the materials investigatedx.
|
|||
|
Show PACS
|
|||
|
|
Couette Viscometer Data Reduction for Materials with a Yield Stress J. Rheol. 29, 369 (1985); http://dx.doi.org/10.1122/1.549818 (10 pages)
Full Text:
|
Download PDF
|
||
|
Show Abstract
Prior studies have shown that the local power law approximation [I. M. Krieger, Trans. Soc. Rheol., 12, 5 (1968)] for calculation of the shear rate in a Couette viscometer provides accurate results for non‐Newtonian fluids which do not exhibit a yield stress, but is less accurate for those that do. An evaluation of this approximation is presented here for the Bingham and Casson plastic (yield) materials in dimensionless form. The magnitude of the error in shear rate, and the conditions under which the maximum error occurs, are shown to depend upon the gap width and location of the yield point as well as the rheological model. The error for a Casson fluid is less than half that for the Bingham material. Furthermore, the maximum error in the apparent viscosity function occurs under different conditions of gap width and yield point, and is considerably less than the error in shear rate for both materials. |
|||
|
Show PACS
|
|||
|
|
J. Rheol. 56, 353 (2012); http://dx.doi.org/10.1122/1.3690105 (32 pages) Online Publication Date: 02 Mar 12
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We examine the accuracy and performance of several leading discrete-element-modeling approaches to predicting equilibrium and dynamic rheological properties of an aqueous, polystyrene suspension. What distinguishes each approach presented is the methodology of handling the solvent hydrodynamics. Specifically, we compare stochastic rotation dynamics (SRD), fast lubrication dynamics (FLD), and dissipative particle dynamics (DPD) methods of including solvent hydrodynamics against each other and against experimental data. Quantities examined are equilibrium structure properties (e.g., pair-distribution function), equilibrium dynamic properties (e.g., long-time diffusivities), and dynamic response (e.g., steady shear). In all approaches, we deploy the Derjaguin-Landau-Verwey-Overbeek (DLVO) potential for colloid–colloid interactions. Comparisons are made over a range of volume fractions and salt concentrations. Long-time diffusivities are especially difficult to compute and exhibit clear discrepancies across methods. Significant effort is devoted in this paper to explain the reasons for the observed inconsistencies. Shear viscosities are predicted to within experimental and numerical error estimates with both SRD and FLD methods, while traditional DPD proves to be too inefficient to be useful in this regard.
|
|||
|
Show PACS
|
|||
|
|
J. Rheol. 56, 625 (2012); http://dx.doi.org/10.1122/1.3700966 (23 pages) Online Publication Date: 17 Apr 12
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Thermoplastic olefin blends of polypropylene (PP) and ethylene octene copolymers (EC) were reactively compatibilized by means of functional reactive compounds capable of forming copolymers at the interface. For this purpose, amine functional groups were first incorporated into a PP in a solution reaction. The aminated PP was then used as the reactive compatibilizer during melt mixing. Linear viscoelastic measurements showed that the compatibilized blends feature the characteristics of materials in the sol–gel transition, with a power-law behavior for the dynamic moduli at low frequencies. The gel-like behavior was more pronounced in the blend with a high level of compatibilizer (10 wt. %). At high frequencies, however, the dynamic properties of all the blends investigated (compatibilized and noncompatibilized) were identical, suggesting that the bulk properties of the blends were not changed by the reactive compatibilization. The presence of a network structure was also confirmed by microscopic observations. A large transient viscosity with a significant and broad overshoot was observed for the compatibilized blends at low shear rate. In addition, the stress of the compatibilized blends relaxed over a much longer time as compared to the noncompatibilized system. The ability of different linear viscoelastic models in predicting the linear viscoelastic behavior of the compatibilized blends was also examined.
|
|||
|
Show PACS
|
|||
|
|
Reversible shear thickening in monodisperse and bidisperse colloidal dispersions J. Rheol. 40, 899 (1996); http://dx.doi.org/10.1122/1.550767 (18 pages)
Full Text:
|
Download PDF
|
||
|
Show Abstract
Reversible shear thickening is measured in model colloidal suspensions of silica that exhibit near hard‐sphere behavior. Flow dichroism measurements and the colloidal stress‐optical relationship prove that hydrodynamic interactions drive the shear thickening transition. Turbidity and flow‐small angle neutron scattering (flow‐SANS) demonstrate that particles cluster reversibly in the shear thickened state. Further, SANS measurements show that shear thickening occurs without any shear‐induced order‐disorder transition, in contrast to observations for dispersions of charged colloids. A simple force balance predicts the scaling of the critical stress for the onset of shear thickening with particle size and volume fraction. Measurements on bimodal mixtures verify the scaling laws derived from the force balance and provide a strategy for controlling the shear thickening transition. © 1996 Society of Rheology |
|||
|
Show PACS
|
|||
|
|
Nonlinear rheology of model comb polymers J. Rheol. 53, 1133 (2009); http://dx.doi.org/10.1122/1.3191781 (21 pages)
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We measure the stress relaxation of linear comb polymer solutions, after a large amplitude step shear strain. We apply the time-temperature superposition principle in order to construct stress relaxation master curves that span many orders of magnitude in time and cover the entire comb relaxation from early branch retraction to backbone reptation. We find evidence of distinct relaxation processes and dynamic tube dilation that can be attributed to the architectural features of the polymer.
|
|||
|
Show PACS
|
|||
|
|
Molecular constitutive equations for a class of branched polymers: The pom-pom polymer J. Rheol. 42, 81 (1998); http://dx.doi.org/10.1122/1.550933 (30 pages)
Full Text:
|
Download PDF
|
||
|
Show Abstract
Polymer melts with long-chain side branches and more than one junction point, such as commercial low density polyethylene (LDPE), have extensional rheology characterized by extreme strain hardening, while the shear rheology is very shear thinning, much like that of unbranched polymers. Working with the tube model for entangled polymer melts, we propose a molecular constitutive equation for an idealized polymer architecture, which, like LDPE, has multiple branch points per molecule. The idealized molecule, called a “pom-pom,” has a single backbone with multiple branches emerging from each end. Because these branches are entangled with the surrounding molecules, the backbone can readily be stretched in an extensional flow, producing strain hardening. In start-up of shear, however, the backbone stretches only temporarily, and eventually collapses as the molecule is aligned, producing strain softening. Here we develop a differential/integral constitutive equation for this architecture, and show that it predicts rheology in both shear and extension that is qualitatively like that of LDPE, much more so than is possible with, for example, the K-BKZ integral constitutive equation. © 1998 Society of Rheology. |
|||
|
Show PACS
|
|||
|
|
J. Rheol. 56, 27 (2012); http://dx.doi.org/10.1122/1.3669646 (17 pages) Online Publication Date: 15 Dec 11
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
We investigated the rheology of titanium dioxide (TiO2) nanoparticles with various surface modifications in neat and binary blends of polydimethylsiloxane (PDMS) homopolymers of different molecular weights (4 k–77 k). The dispersions for bare, octadecyl-(C18), and PDMS-grafted particles reflect different interaction forces. For bare particles, the relative viscosity decreases monotonically with increasing melt Mw or increasing fraction of long chains (f), consistent with thicker adsorbed layers. The octadecyl(C18)-grafted dispersions show no dependence on melt Mw or f, suggesting that the alkyl groups prevent polymer adsorption or bridging. Therefore, the van der Waals attractions are cut off at a separation on the order of twice the thickness of the C18 chains (≈5 nm), regardless of melt Mw or f. The PDMS-grafted suspensions show an increase in relative viscosity with increasing melt Mw or f, consistent with wetted polymer brushes for P < N and dewetted layers for P > N. The power law we developed previously fits the shear-rate dependent viscosities with a structural relaxation time that scales with the magnitude of the attraction, thereby reflecting the microscale dynamics.
|
|||
|
Show PACS
|
|||
|
|
Rheology of schizophyllan solutions in isotropic and anisotropic phase regions J. Rheol. 48, 1147 (2004); http://dx.doi.org/10.1122/1.1781170 (20 pages) Online Publication Date: 09 Sep 04
Full Text:
|
Download PDF
|
||
|
Show Abstract
In this paper, we discuss the rheological properties of aqueous solutions of a rigid triple-helical polysaccharide, schizophyllan (SPG), in isotropic, biphasic, and fully anisotropic phases. Both steady shear and dynamic rheological behaviors reveal remarkable changes when SPG solutions pass through the three phases. The steady shear flow exhibits shear thickening at low shear rates for anisotropic SPG liquid crystalline samples, which is attributed to the shear-induced cholesteric to nematic transformation. The first normal stress difference and transient rheological experiments demonstrate that director tumbling is absent or negligible in SPG liquid crystals in the range of examined shear rates. Additionally, the stress relaxation of SPG liquid crystals after flow cessation shows an inverse relation between the relaxation time and preshear rate, as expected by Larson and Mead’s theory [Larson and Mead (1989)]. Small amplitude oscillation measurements following flow cessation show decreasing complex modulus with time for SPG liquid crystals, which is probably related to an increase of molecular orientation after flow cessation. The evolutions of complex modulus after flow cessation are discussed in terms of chain persistence length. © 2004 The Society of Rheology. |
|||
|
Show PACS
|
|||
|
|
New measures for characterizing nonlinear viscoelasticity in large amplitude oscillatory shear J. Rheol. 52, 1427 (2008); http://dx.doi.org/10.1122/1.2970095 (32 pages)
Full Text:
Read Online (HTML)
|
Download PDF
|
||
|
Show Abstract
Characterizing purely viscous or purely elastic rheological nonlinearities is straightforward using rheometric tests such as steady shear or step strains. However, a definitive framework does not exist to characterize materials which exhibit both viscous and elastic nonlinearities simultaneously. We define a robust and physically meaningful scheme to quantify such behavior, using an imposed large amplitude oscillatory shear (LAOS) strain. Our new framework includes new material measures and clearly defined terminology such as intra-/intercycle nonlinearities, strain-stiffening/softening, and shear-thinning/thickening. The method naturally lends a physical interpretation to the higher Fourier coefficients that are commonly reported to describe the nonlinear stress response. These nonlinear viscoelastic properties can be used to provide a “rheological fingerprint” in a Pipkin diagram that characterizes the material response as a function of both imposed frequency and strain amplitude. We illustrate our new framework by first examining prototypical nonlinear constitutive models (including purely elastic and purely viscous models, and the nonlinear viscoelastic constitutive equation proposed by Giesekus). In addition, we use this new framework to study experimentally two representative nonlinear soft materials, a biopolymer hydrogel and a wormlike micelle solution. These new material measures can be used to characterize the rheology of any complex fluid or soft solid and clearly reveal important nonlinear material properties which are typically obscured by conventional test protocols.
|
|||
|
Show PACS
|
|||
|
|
Unstable flow and nonmonotonic flow curves of transient networks J. Rheol. 45, 1465 (2001); http://dx.doi.org/10.1122/1.1413507 (13 pages)
Full Text:
Read Online (HTML)
|
Download PDF
|
|||||||||||||||
|
Show Abstract
We have measured the nonlinear rheological response of a model transient network over a large range of steady shear rates. The system is built up from an oil in water droplet microemulsion into which a telechelic polymer is incorporated. The phase behavior which comprises a liquid–gas phase separation and a percolation threshold is characterized. The rheological measurements are performed in the one phase region above the percolation line. Shear thinning is observed for all samples, leading in most cases to an unstable stress response at intermediate shear rates. We built up a very simple mean field model which involves the reduction of the residence time of the stickers in the droplets due to chain tensions at high shear. The computed flow curves are nonmonotonic with a range where the stress is a decreasing function of the rate, a feature that indeed makes homogeneous flows unstable. The computed the flow curves compare well to the experiments. © 2001 The Society of Rheology. |
||||||||||||||||
|
Show PACS
|
||||||||||||||||
|
|
A Mechanism for Non‐Newtonian Flow in Suspensions of Rigid Spheres Trans. Soc. Rheol. 3, 137 (1959); http://dx.doi.org/10.1122/1.548848 (16 pages)
Full Text:
|
Download PDF
|
||
|
Abstract Unavailable
|
|||
|
Show PACS
|
|||
This Publication
Scitation
SPIN
Google Scholar
PubMed