Effects of long-term thermal/vacuum ageing on TSDC spectra of irradiated polyimide

TSDC techniques have been used to examine the behaviour of polyimide that has been subjected to different ageing regimes comprising combinations of gamma irradiation in vacuum to doses of 50 and 500 kGy followed by a constant temperature of 420 K under vacuum for periods ranging to a maximum of 48 months. The resulting TSDC spectra are complex and influenced strongly by the different regimes.