Homocharge Relaxation in Polyimide Films with Different Macromolecule Rigidity

The relaxation of homocharge of polyimide films with different rigidity of macromolecules was studied by thermal activation spectroscopy. We used laboratory films R-BAPB, PMDA-ODA and DP-OTD. Using the method of computer simulation, complex spectra of thermally stimulated depolarization (TSD) currents are decomposed into individual elementary peaks, which are described by first-order kinetic equations. The activation energies of relaxation processes were determined. It has been shown that the highest thermal stability of the electret state is characteristic of the rigid-chain polyimide DP-oTD. The mechanisms of homocharge relaxation in R-BAPB, PMDA-ODA, and DP-OTD polyimide films previously exposed to a corona discharge have been determined. The maximum at the TSD currents is associated with the relaxation of the charge due to the intrinsic conductivity of the dielectric. The activation energy of conduction is from 1.05 eV to 1.58 eV.