The influence of moisture on charge relaxation in modified polyimide films

The charge relaxation processes in the films based on polyimide and polytetrafluoroethylene (the latter serves as a coating) have been studied. The coating effect on the charge relaxation processes in the films under high humidity conditions was revealed. The obtained experimental data was analyzed in the context of the present-day knowledge of the charge relaxation mechanism. The complex spectra of the thermally stimulated depolarization currents (TSDC) were resolved into individual components described by the first-order kinetics equations using computer simulation. The TSDC activation energies were calculated and interpreted in terms of the mechanism of release of charge carriers. It was shown that the polytetrafluoroethylene coats on film surfaces lead to an essential increase in the electret state stability at elevated temperature and high humidity.