Transient Current and Space Charge in Gamma Irradiated PTFE: Discussion on Heterocharge Formation

Heterocharges in gamma irradiated polymers are often observed but their origin and dynamic are not fully understood. The main objective of our work is to explore heterocharges behavior in gamma irradiated polytetrafluoroethylene under DC field, in correlation with transient current, by using exactly the same protocol for space charge and current measurements. Furthermore, the reversal of applied voltage is expected to be a good tool to explore heterocharges in this case. The heterocharge build-up seems associated with a region near the film surface with lower electrical conductivity. The heterogeneity could arise from strong surface oxidation of the PTFE layer promoted by gamma irradiation.