The effect of charge trapping on final thermally stimulated discharge currents in polyethylene naphthalate (PEN)

Abstract

The aim of the work presented in this paper was to analyse final thermally stimulated discharge current that appeared at the end of discharging process, when the temperature was increased from 100 to 180°C. This current exhibit two probable peaks. To fit the experimental data, two Gaussian components were used: the first one centred at 128°C near Tg and the second one at 150°C associated to pre-melting of crystallites. The sample (gold metallised PEN film 25μm thick) was submitted, prior to this process, to 72MV/m DC field during ten thousand seconds. The DSC analyse showed a Tg at 128°C and an endothermic peak at 150°C. These results imply that the trapped space charge cannot release from the sample and require an increasing of temperature. Above Tg, the molecular motion facilitates the de-trapping process.