抄録
Complex permittivity spectra were obtained in a wide temperature and frequency range from 20 to 200°C and from 10-2 to 105 Hz for polydicyclopentadiene resin (PDCPD). For comparison, two epoxy resins, one with a similar glass transition temperature (Tg) to PDCPD and the other with a lower Tg, were used. As a result, PDCPD shows much smaller values of εr' and εr'' than the two epoxy resins in nearly the whole temperature and frequency range. The differences of εr' and εr'' between PDCPD and the epoxy resin with a similar Tg are also significant at low frequencies and at high temperatures. The increase in εr' is attributable to the accumulation of hetero space charges in front of the electrodes. On the other hand, the increase in εr'' is an indication of the increase in Joule heat caused by the enhanced charge transport. Therefore, the experiental results indicate that PDCPD possesses better electrical insulating properties than epoxy resin. Furthermore, analysis using complex electric modulus, which is the inverse of the complex permittivity, has revealed very clearly that both charge transport and dipolar orientation are much more difficult in PDCPD than the two epoxy resins.
