Thermally stimulated current studies on polyimide film

We have experimentally observed that there are two peaks in the TSC-spectra of Du Pont polyimide film. The low temperature peak which appears in the 50°-70°C temperature range is possibly ascribed to the dipole depolarization of unimidized polyamic acid in the film, whereas the high temperature peak which exists in the 160°- 180°C temperature range is clearly due to the depolarization of the space charge of ions, according to our experimental results. The ions are principally generated through the ionization of unimidized polyamic acid and are bound into a Frohlich two-potential well.