Hydration effects and surface conductivity of corona charged and gamma-irradiated insulating polymers and ceramics

The surface conductivity of aluminum oxide within the range of 0-80% RH (relative humidity) appears to be significantly higher than those of polyethylene and polyetherether ketone. Even at the highest hydration level (80% RH) the surface conductivity of the ceramic has been observed to be an order of magnitude less than that of bulk water. The decay behavior of corona-deposited surface charges on the ceramic and the polymers shows that the charge injection is not the dominant mechanism. An electronic conduction model provides a good agreement with the observed result of the surface current in hydrated polyethylene. >