scispace - formally typeset
Search or ask a question
Topic

Shear thinning

About: Shear thinning is a research topic. Over the lifetime, 4156 publications have been published within this topic receiving 98336 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In this article, the authors derived a flow equation for pseudoplastic flow that is associated with the formation and rupture of structural linkages in both aqueous and nonaqueous media.

1,703 citations

Journal ArticleDOI
TL;DR: In this paper, a special case of thise theory is given by a model with only one configuration tensor which both the stress and mobility tensors depend on, and a further specialization is introduced by assuming a linear dependency of stress tensors on the configuration tensors.
Abstract: Some time ago a theory of elastic fluids such as concentrated polymer solutions and melts was presented based on the concept of a multitude of penetrating statistical continua. The configurations of these depend on the deformation history, and their relative motion is determined by the coordinated part-stress in connection with a tensorial mobility which is a function of all configuration tensors. The simples special case of thise theory is given by a model with only one configuration tensor which both the stress and mobility tensors depend on. In this paper a further specialization is introduced by assuming a linear dependency of stress as well as of mobility tensors on the configuration tensor. Some relationship to a modified retation model, recently presented by Curtiss and Bird, is hereby established. This model which is of the rate-type and is non-linear in the configuration and stress tensors, respectively, nevertheless permits analytic solutions of some of the most important types of flow. These are explicitly given for both steady and transient extensional and shear flows. Besides shear thinning and non-vanishing first and second normal-stress differences, an extensional viscosity with finite asymptotic values as well as non-exponential stress relaxation and start-up curves are predicted, with stress-overshoot at least in the case of shear flow.

894 citations

Journal ArticleDOI
TL;DR: In this paper, the rheology of suspensions of monodisperse particles of varying aspect ratios, from oblate to prolate, and covering particle volume fractions from dilute to highly concentrated.
Abstract: We present data for the rheology of suspensions of monodisperse particles of varying aspect ratio, from oblate to prolate, and covering particle volume fractions from dilute to highly concentrated....

743 citations

Journal ArticleDOI
TL;DR: In this article, a molecular constitutive equation for an idealized polymer architecture, called a pom-pom, has been proposed, which predicts rheology in both shear and extension.
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.

724 citations

Journal ArticleDOI
TL;DR: 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 as discussed by the authors.
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). ...

710 citations


Network Information
Related Topics (5)
Phase (matter)
115.6K papers, 2.1M citations
82% related
Polymer
131.4K papers, 2.6M citations
81% related
Adsorption
226.4K papers, 5.9M citations
78% related
Particle
96.5K papers, 1.9M citations
78% related
Nanocomposite
71.3K papers, 1.9M citations
77% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023221
2022449
2021191
2020204
2019199
2018176