Electrical conduction processes in polyimide films - I

In this paper, extensive investigations of the absorption, desorption and transport currents are carried out in polyimide films (Kaptonreg) over the temperature range of 50 to 200degC and electric fields up to 12 MV/m. The main purposes of the study are to investigate the absorption and desorption processes and to establish a basis for comparison for the study of electrical conduction processes in polyimide-teflon layered films, for the first time, to be dealt with in another paper. The influence of electric field strength, temperature and electrode materials on currents are studied. The experimental results indicate that the currents decay with the time at the electric field and temperatures studied. The currents are substantially identical with both aluminum and silver electrodes. Application of various theories shows that the mechanism for absorption currents in un-layered polyimide for the temperature range 50-120degC is dipolar; at higher temperatures generation of charge carriers within the volume occurs by ionic processes.