DC conduction in polyethylene films under high electric field after annealing

It is well known that the electrical properties of polymers are significantly influenced by the morphology. High-density polyethylene (HDPE) is a semicrystalline polymer with crystalline and amorphous regions. HDPE specimens with different crystallinities have been prepared by varying the annealing conditions. Based on the conventional thermally activated electronic injection process, the dependence of DC conduction on the crystallinity of PE has been studied. We calculated that with the increase of crystallinity from 52.8% to 68.2%, values of the metal/dielectric contact potential for samples of PE decrease from 2.75 eV to 2.24 eV. We presumed that the morphological microstructure of the transcrystals in the electrode-polymer interface is responsible for the difference between the potential energy of an electron at the Fermi level in the metal electrode and that, of one in the conductive state in the polymer bulk.