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Title:The dynamic properties of concentrated charge stabilized suspensions
Author(s):Chen, Liang Bin
Doctoral Committee Chair(s):Zukoski, Charles F.
Department / Program:Chemical and Biomolecular Engineering
Discipline:Chemical and Biomolecular Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Engineering, Chemical
Abstract:The equilibrium properties and flow behaviors of concentrated charge stabilized suspensions are investigated in this dissertation. Monodispersed polystyrene particles with diameters ranging from 35 nm to 250 nm are used. Suspensions with volume fractions ranged from 0.10-0.62 are examined. Equilibrium elastic moduli and osmotic pressures are characterized. Rheological and osmotic pressure determinations of the location of the order/disorder phase transition are found to agree. Yielding and catastrophic shear thinning where the suspension viscosity decreases discontinuously with increasing shear stress are measured with both constant stress and constant strain rate rheometers.
The osmotic pressure and elastic modulus show volume fraction dependencies predicted by models using screened coulomb repulsive potential. The rheological studies show that suspensions exhibit a zero shear rate viscosity when disordered but show to have static and dynamic yield stresses when ordered. Superanomalous flow where shear stress is a decreasing function of shear rate is observed for the first time in ordered suspensions and is related to the structural transition through optical and small angle neutron scattering studies. Dynamic variables such as static yield stress, dynamic yield stress and critical stress are found to scale with the equilibrium modulus.
Issue Date:1992
Rights Information:Copyright 1992 Chen, Liang Bin
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9215787
OCLC Identifier:(UMI)AAI9215787

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