Science and Technology Production
Article
Authorship
Constantino Grosse
;
PEDROSA, SUSANA ELIZABETH
;
Vladimir Shilov
Date
1999
Publishing House and Editing Place
Elsevier
Magazine
JOURNAL OF COLLOID AND INTERFACE SCIENCE,
vol. 220
(pp. 31-41)
Elsevier
Summary
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SIGEVA
The a-dispersion amplitude of suspensions of colloidal particles is usually calculated from the low-frequency asymptotic of the frequency-dependent solution of the electrodiffusion equations. Since these equations written in spheroidal coordinates do not separate, no theoretical results exist for the low-frequency dielectric properties of suspensions of spheroidal particles. In order to sidestep this problem, we used another method which relates the dielectric properties to the energy stored in...
The a-dispersion amplitude of suspensions of colloidal particles is usually calculated from the low-frequency asymptotic of the frequency-dependent solution of the electrodiffusion equations. Since these equations written in spheroidal coordinates do not separate, no theoretical results exist for the low-frequency dielectric properties of suspensions of spheroidal particles. In order to sidestep this problem, we used another method which relates the dielectric properties to the energy stored in the system (Grosse, C., Ferroelectrics 86, 171 (1988)) which, at low frequencies, mainly corresponds to the Gibbs free energy associated to the field-induced electrolyte concentration changes outside the double layer (Grosse, C. and Shilov, V. N., J. Colloid Interface Sci. 193, 178 (1997)). This method permits us to calculate the static permittivity by solving a purely static problem, which makes it possible to calculate analytically the a-dispersion amplitude of suspensions of spheroidal particles since the electrodiffusion equations do separate in the static case. We also calculate the characteristic time of the a-dispersion from the dispersion amplitude and the static and high-frequency values of the dipolar coefficient. The analytical results obtained are presented and discussed for both prolate and oblate geometries, and for parallel, perpendicular, and random orientations of the particles with respect to the applied field.
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Key Words
INCREMENTDIELECTRICSPHEROIDALSUSPENSIONS