The electrical properties of heterogeneous mixtures containing an oriented spheroidal dispersed phase

Abstract

Theoretical equations for the permittivity and conductivity of a heterogeneous mixture containing an oriented dispersed phase of spheroidal shape are limited to low volume fractions of dispersed phase. Two new sets of equations have been derived here for such systems using approaches which have been shown previously to be applicable to higher concentrations. One set has generalised forms of equations given by Bruggeman and Hanai and includes simplifications applicable to oil in water (O/W) and water in oil (W/O) systems. The other set has generalised forms of an equation given by Looyenga. Tabulated mixture permittivityε and dielectric incrementΔε values are presented and, with the exception ofO 〈W systems containing prolate spheroids, the two types of equation show significant differences in bothε andΔε. For both typesΔε is strongly dependent on the ratio of the conductivities of the two media of aW/O system.

The relevance of the mixture equations to the electrical behaviour of micellar, microemulsion and liquid crystalline systems is considered.