Electric conductivity of ethylene propylene copolymer: effect of alumina

The dependence of the electric conductivity, σ, on the electric field, E, was measured on ethylene propylene (EPDM) copolymer with and without alumina filler. It was found that a Schottky-like charge injection process conjugated to a modified Poole-Frenkel model for the bulk conduction was necessary for accounting the experimental results for samples without alumina filler. However, the experimental results for samples with alumina filler showed that the conductivity σ depends also on the sample thickness suggesting a space-charge perturbed bulk conduction