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Vladimir N. Matveenko, Eugine A. Kirsanov
Viscosity
of concentrated water in oil emulsions within the structural model
Abstract
Abstract. A structural rheological
model is used to interpret viscosity and flow curves of concentrated emulsions
consisting of water droplets in oil. It is shown that rheological curves can be
divided into separate shear rate intervals, within which the experimental data
are approximated by the rheological equations of the structural model. The
generalized flow equation describes the destruction of the emulsion structure
under the action of tensile hydrodynamic forces. The second rheological
equation additionally includes a rate constant related to the process of
formation of droplet aggregates under the action of compressive hydrodynamic
forces. The dependence of the coefficients of the generalized flow equation ηc1/2 and τc1/2on the volume concentration ะค is described by separate
equations in which hydrodynamic parameters are used. The compactness
coefficient χassociated with spontaneous droplet rupture changes in a
complex manner with increasing concentration, possibly due to the formation of
aggregates and changes in droplet shape due to deformation upon droplet
contact.
Key words: rheology of emulsions, viscosity curves,
flow curves, structural rheological model, dependence of the coefficients of
the rheological equation on volumetric concentration
Copyright (C) Chemistry Dept., Moscow State University, 2002
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