Study of AC electrical conduction mechanisms in an epoxy polymer

The AC conductivity of an epoxy resin was investigated in the frequency range 10−1−106 Hz at temperatures ranging from -100 to 120 °C. The frequency dependence of σac was described by the law: σac=ωε0ε′′HN+Aωs. The study of temperature variation of the exponent (s) reveals two conduction models: the AC conduction dependence upon temperature is governed by the small polaron tunneling mechanism (SPTM) at low temperature (-100 -60 °C) and the correlated barrier hopping (CHB) model at high temperature (80-120 °C).