Space charge and electrical breakdown in polyphenylene sulfide films

Direct and quantitative measurement of space charge was performed for PPS (poly-p-phenylene sulfide), and positive space charge was observed. In biaxially stretched semicrystalline PPS, homo space charge is formed near the anode, whereas, in unstretched amorphous PPS, space charge ranges almost uniformly throughout the sample. The amount and distribution of the detected space charges explain the effects of prestress on breakdown in these materials, suggesting that the breakdown does not always take place in the region with the highest local field. The dependence of space charge distribution on morphology corresponds to the difference in impulse breakdown strength and conduction current, and is explained by higher effective carrier mobility due to lower trap density in unstretched amorphous PPS