The influence of gamma radiation on Electrical behaviour of isotactic polypropylene

Electrical behavior of gamma irradiated isotactic polypropylene (iPP) films for different applied field and temperatures is reported in this work. The induced change in the transient charging current for the irradiated film, in comparison of virgin one, was studied in the dc field range 2-4 MV/m, at different temperatures (23-100°C). A 25 microns thick film was irradiated in air at room temperature by means of a ⁶⁰Co gamma source at a dose of 100 kGy. A considerable increase in isochronal current for the irradiated films was observed. Further, it was also noticed that oscillations were detected in transient charging current, for the irradiated sample but not in virgin one. The different oscillations periods were related to applied field and temperature. This behaviour was associated with charge packet propagation which is the consequence of changes in the polymer microstructure induced by gamma radiation.