INCREASE IN BREAKDOWN STRENGTH OF PE FILM BY ADDITIVES OF AZOCOMPOUNDS

PE films with various additives were prepared by the solution-grown me thod. The thickness of the films ranged from 5 to 25 mu m. Six differe nt azocompounds were used as additives. The results show that BDS Omic ron for the film with additives was higher than that for the film with out additives in the temperature range from -35 to 30 degrees C. The i ncreasing ratio of BDS depended on the composition of the additives us ed. Our results indicate that the breakdown of the film is induced by an electron avalanche. The conduction current through the film in the high electric field region was reduced by using the additives. The dep endence of the conduction current on additives corresponds to that of BDS; a higher BDS is realized for films with additive by which the con ductive current is controlled at the lower value. It was considered th at the reduction of current by the additive is due to either the trapp ing effect or the excitation effect of the additive. The trap level fo r the additive and the excitation energy depend upon the type of radic al connected on the benzene ring of the additive: electron-accepting o r electron-donating type. The results suggested that high BDS and smal l current are obtained when the azocompound on which the electron-acce pting radical is connected is used as the additive.