STUDY OF THERMAL CURRENTS IN COCL2-DOPED POLY (VINYL ALCOHOL) FILMS IRRADIATED WITH GAMMA-RAYS

Thermally stimulated depolarisation current (TSDC) and time-dependent conduction current of unirradiated and gamma-irradiated pure and CoCl2 -doped PVA films have been measured. Doses in the range 21-75 Mrad wer e used. The TSDC of pure and doped PVA before and after irradiation re vealed a T(g) relaxation peak. The induced changes in the peak current (I(m)) of the glass relaxation peak are composition and dose dependen t. A marked decrease in TSDC corresponding to the main glass relaxatio n peak is observed with ageing time. The role of gamma-irradiation in perturbing the orientation of the dipoles and/or chain segments was in ferred from the disappearance of some sub-T(g) relaxation peaks. The t hermally activated mobility of charge carriers is confirmed from calcu lations of drift mobility at different gamma doses and temperatures.