Increase in Breakdown Strength of PB Film by Addition of Polycyclic Compound

Abstract

The An increase in dc breakdown strength (BDS) for LDPE film was found using the additives of polycyclic compounds: anthracene(An), perylene(Pr), 9, 10 bromo-anthracene(Br_An), 1, 7 bromo-perylene(Br_Pr). We also used an additive of p-nitorobenzene-azoresorcinol(Az_hn). The experimental results indicate that all the additives used are effective in increasing BDS. The most effective additive is Br_An. BDS for the film with this additive is about 1.6 times higher than that for the film without additive. These results are observed in the temperature range between -20°C and 20°C. The BDS characteristics indicate that the breakdown of film may be due to an electron avalanche from the cathode. The reason for the increase in BDS is studied by comparing the experimental results for the five additives. UV absorption spectra for the films with additive suggest that the increase in BDS may not result mainly from the kinetic energy absorption due to the excitement of the additive at the collision between additive and electron carrier. TSC curves indicate that the quantity of negative charge trapped in the film is increased by the existence of the additive, which may locate at the boundary between the crystalline and amorphous regions in the film. It is considered that the increase in BDS may be achieved by a trapping of the electron carrier by the additive. The electron carrier scattering due to the dipole moment of the additive is no effective factor for the increase of BDS in this study because the polycyclic compounds used have no dipole.