抄録
Antioxidants are usually used in polyethylene for power cable insulation. We investigated the effects of antioxidants on the space-charge behavior in low-density polyethylene (LDPE) utilizing laser-induced-pressure-pulse (LIPP) technique.
Among many factors affecting space-charge characteristics, we studied effects of applied electric field, residual amount of antioxidants in LDPE and sample thickness. Results obtained in the present study were as follows. 1) Space-charge behavior changes with applied electric fields, and effects of anrioxidants on space charge are classified into three field regions. In the low field region (<1.2 MV/cm), hetero sgace charges are formed near both electrodes, which may be due to carriers generated in the bulk. In the intermediate field region (<1.6MV/cm), hole injection from the anode becomes dominant, resulting in the formation of positive homo space charge near the anode and positive hetero space charge near the cathode. In the high field region (>1.8MV/cm), hole injection increases and electron injection from the cathode drastically increases. This leads to the formation of positive homo space charge near the anode and negative homo space charge near the cathode. 2) With increasing the residual amount of antioxidants, electron injection from the cathode is dominantly enhanced. 3) The thickness dependence of space-charge behavior is explained by considering the change in the absolute residual amount of antioxidant with thickness.
