Degradation of Dielectric Properties of Polyethylene by Combined Y-Irradiation and Thermal Stresses

Abstract

Degradation of dielectric properties polyethylene under the combined environment of γ-irradiation and thermal aging has been studied. To exclude the effect of additive agents and to minimize the effect of the process limited by diffusion of oxygen on the degradation, a 25 μm thick low-density polyethylene ene film free from additives has been used. Dielecc re relaxation is used as a tool to study the oxidative degradation. It is found that the primary dispersion of polyethylene shifts to higher temperatures with oxidation. There is some difference nce in temperature of primary dispersion according to the order of application of thermal aging and γ-irradiation. The reason for it is explained in terms of chain scission, cross linking and dipole-dipole interaction.