The Effect of Space charge on Isothermal and non-isothermal Currents in Polyethylene Naphthalate

This paper presents an experimental results obtained by using three investigation methods. The temperature effect on space charge behavior, in semi crystalline polyethylene naphthalate (PEN), under electrical strength, was analyzed. The Anomalous charging current, which is generally attributed to space charge, was observed. The non-isothermal current exhibited two peaks one located at 130 ∘C near the glass transition temperature Tg, and the other, which was associated to pre-melting of crystallites, at 150 ∘C. The DSC analyze showed a Tg at 128 ∘C and an endothermic peak at 150 ∘C. From these results it can be concluded that the trapped space charge can not release from the sample and requires an increase of temperature. Above Tg, the molecular motion facilitates the de-trapping of the charge.