Space charge observation of polyimide films under DC electric fields

Space charge formation under dc electric field in various types of polyimide films made with different monomers were observed by the high-resolution PEA method by increasing the dc electric field manually from 0 to 100 kV/mm. Charge injection was recognised at 50 kV/mm in the three types made of the most common monomer, and the accumulated charge decays gradually with time. In two types of polymers made from another monomer, on the other hand, no charge injection was observed up to 100 kV/mm.