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Title: Nonequilibrium behavior of dense suspensions of uniform particles: Volume fraction and size dependence of rheology and microstructure

Abstract

The rheological and microstructural properties of dense suspensions of uniform, charge stabilized colloidal spheres with diameters greater than 200 nm are investigated at volume fractions just below the ordering transition up to 0.6. Shear stresses marking static and dynamic yielding, discontinuous shear thinning, and shear thickening are weakly dependent on volume fraction and particle size when scaled on the crystal's elastic modulus [ital G][sub 0]. As shear stress is increased microstructures evolve through similar states independent of volume fraction. As rest, presheared suspensions exhibit long-range orientational order. Above the dynamic yield stress, the suspensions deform with a polycrystalline microstructure which, at intermediate shear rates, evolves to hexagonally close-packed planes lying parallel to the rheometer walls. At higher shear rates the suspensions melt. Thickening is only observed above a volume fraction of 0.4--0.5, depending on particle size and at shear rates above that where the hexagonal close packing has been degraded. Shear rates characteristic of changes in flow properties and microstructure increase exponentially with volume fraction in the same manner as [ital G][sub 0]. As a consequence, a volume fraction independent constitutive response is observed when stress is scaled on [ital G][sub 0] and the shear rate is scaled on [italmore » G][sub 0]/[mu]. Here [mu] is the continuous phase viscosity.« less

Authors:
;  [1]
  1. Department of Chemical Engineering and Beckman Institute, University of Illinois, Urbana, Illinois 61801 (United States)
Publication Date:
OSTI Identifier:
6721187
DOE Contract Number:  
FG02-91ER45439
Resource Type:
Journal Article
Journal Name:
Journal of Rheology; (United States)
Additional Journal Information:
Journal Volume: 39:1; Journal ID: ISSN 0148-6055
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COLLOIDS; MICROSTRUCTURE; SHEAR PROPERTIES; SUSPENSIONS; CRYSTALLIZATION; HEXAGONAL CONFIGURATION; RHEOLOGY; SCALING LAWS; VISCOSITY; CONFIGURATION; DISPERSIONS; MECHANICAL PROPERTIES; PHASE TRANSFORMATIONS; 661300* - Other Aspects of Physical Science- (1992-)

Citation Formats

Chow, M K, and Zukoski, C F. Nonequilibrium behavior of dense suspensions of uniform particles: Volume fraction and size dependence of rheology and microstructure. United States: N. p., 1995. Web. doi:10.1122/1.550687.
Chow, M K, & Zukoski, C F. Nonequilibrium behavior of dense suspensions of uniform particles: Volume fraction and size dependence of rheology and microstructure. United States. https://doi.org/10.1122/1.550687
Chow, M K, and Zukoski, C F. 1995. "Nonequilibrium behavior of dense suspensions of uniform particles: Volume fraction and size dependence of rheology and microstructure". United States. https://doi.org/10.1122/1.550687.
@article{osti_6721187,
title = {Nonequilibrium behavior of dense suspensions of uniform particles: Volume fraction and size dependence of rheology and microstructure},
author = {Chow, M K and Zukoski, C F},
abstractNote = {The rheological and microstructural properties of dense suspensions of uniform, charge stabilized colloidal spheres with diameters greater than 200 nm are investigated at volume fractions just below the ordering transition up to 0.6. Shear stresses marking static and dynamic yielding, discontinuous shear thinning, and shear thickening are weakly dependent on volume fraction and particle size when scaled on the crystal's elastic modulus [ital G][sub 0]. As shear stress is increased microstructures evolve through similar states independent of volume fraction. As rest, presheared suspensions exhibit long-range orientational order. Above the dynamic yield stress, the suspensions deform with a polycrystalline microstructure which, at intermediate shear rates, evolves to hexagonally close-packed planes lying parallel to the rheometer walls. At higher shear rates the suspensions melt. Thickening is only observed above a volume fraction of 0.4--0.5, depending on particle size and at shear rates above that where the hexagonal close packing has been degraded. Shear rates characteristic of changes in flow properties and microstructure increase exponentially with volume fraction in the same manner as [ital G][sub 0]. As a consequence, a volume fraction independent constitutive response is observed when stress is scaled on [ital G][sub 0] and the shear rate is scaled on [ital G][sub 0]/[mu]. Here [mu] is the continuous phase viscosity.},
doi = {10.1122/1.550687},
url = {https://www.osti.gov/biblio/6721187}, journal = {Journal of Rheology; (United States)},
issn = {0148-6055},
number = ,
volume = 39:1,
place = {United States},
year = {1995},
month = {1}
}