Electroviscous Fluids. I. Rheological Properties

Abstract

Electroviscosity is defined in this introductory paper as an essentially instantaneous reversible change in apparent viscosity when a fluid is subjected to an externally applied electric field. The electroviscous properties of silica and calcium titanate dispersions are typical of most electroviscous systems and were found to be a function of many parameters such as composition, shear rate, field strength, frequency, and temperature. When only one parameter is varied, electroviscous effects increase with increasing volume fraction of disperse phase, field strength, and temperature, but decrease with increasing shear rate and frequency. Electroviscosities are proportional to the square of the field strength and inversely proportional to the first power of the shear rate. Induced interfacial polarization on and near the particle surface and the resulting interactions between the polarized double layers, and the polarized double layers and particles are used to explain the electroviscous phenomenon.