Simultaneous thermally stimulated depolarization conductivity and luminescence in polyethylene

Thermally stimulated depolarization (TSD), conductivity (TSC) and luminescence (TSL) are now firmly established as experimental techniques for the study of charge trapping and movement in solid dielectrics. However, TSD/TSL and TSC/TSL should be measured simultaneously on the same sample in order to maximise the information which can be drawn from the data; unfortunately few authors have reported simultaneous measurements. In this paper we present the results of simultaneous measurement of TSD/TSL and TSC/TSL on low density polyethylene samples X-irradiated in vacuum at liquid nitrogen temperature and subsequently heated to room temperature. In order to investigate the possible role of carbonyl (C = 0) groups in electron trapping, some samples were exposed to an oxygen/ozone mixture at 40°C and the resulting changes in the glow-curves noted. We also heated some samples to 100°C, before X-irradiating them at liquid nitrogen temperature, in order to investigate the possible dependence of the electron trapping sites on the morphology of the samples.