Electrical conduction and breakdown in polyolefin with carbonyl groups

The temperature dependence of electrical conduction in polyolefin with low carbonyl amounts is examined based on studies of d.c. conduction, space charge distribution, and impulse breakdown strength. The materials used are low-density polyethylene (LDPE) and the copolymer of LDPE and carbonyl groups. The d.c. conduction current is measured at room temperature, 50°C, 70°C, and 90°C; and 15min values are taken after application of electric fields of 0.27, 0.37, and 0.47 MV/cm. The space charge distribution is examined by the pulsed electroacoustic method, and is recorded after the sample is short-circuited. The breakdown experiments are conducted via an impulse voltage with a wave shape of 1.2/50 μs. The dielectric strength is examined with a fixed electrode system, wherein the samples are placed in an epoxy resin with stainless-steel electrodes.