Dielectric studies on emulsion of aqueous agarose gel in hydrophobic colloidal silica-oil gel.

Abstract

In order to characterize the state of aggregation, dielectric relaxation due to interfacial polarization of a system of aqueous agarose gel particles dispersed in a squalane medium jellified by hydrophobic colloidal silica (denoted below as G/(S·O) emulsion) was investigated over a frequency range from 10kHz to 3MHz. The value of the parameter α, a measure of the distribution of relaxation frequency determined from complex plane plots, was zero when there was no aggregation. It was positive while aggregation was progressing and fell toward zero as the aggregation approached the steady state during storage. When the dependence of α on the uniformity of particle size was taken into account, the transient characteristics of dielectric relaxation represented by the positive value of α seemed to indicate that the mode of ion diffusion through the interface layer between particles in contact changed depending on the magnitude and particle size variation of particle clusters. Microscopic observation during aggregation supported the hypothesis that positive α appeared during the progressive stage of aggregation as a result of a transient deviation from uniformity of aggregation. The influence of aggregation on other dielectric parameters is also discussed.