Thermally stimulated dielectric polarization release in water-in-oil microemulsions

Abstract

The thermally stimulated depolarization (TSD) of a water-in-oil microemulsion was analyzed as a function of increasing water contents in the concentration interval 0.024 ⩽ c ⩽ 0.5 (c = mass fraction). Two main peaks were clearly detected in the depolarization vs temperature spectra. The first peak, with its maximum at 253°K, persists over the whole range of concentration and is ascribed to the polarization of the electrified water-oil interface; the second peak, centered around 288°K, was interpreted in terms of the orientation of some structured dipolar entities which develop in a restricted range of concentrations preceding the liquid-crystalline phase. The activation energy and the relaxation time of the orientation process associated with the first depolarization peak (253°K) was calculated following the Bucci and Fieschi method.