Measurement of surface resistivity on gamma-ray irradiated polymer insulating materials

Polymer insulating materials used in radioactive environment are subjected to a great risk of surface dielectric breakdown which may lead to catastrophic failure of electrical devices. Understanding the effect of energetic radiation on the surface insulation property is of importance for the safe use of the material. This paper shows investigation of surface resistivity measurement on gamma-ray irradiated low density polyethylene (LDPE) and polybutylene naphthalate (PBN) with different relative humidity. Results obtained indicate that the surface resistivity for both the materials decreases with the growth of the total dose of irradiation. The surface resistivity measured with high relative humidity is smaller than that obtained with low relative humidity. ATR-FTIR measurement reveals that polar groups are formed on surface layer of the polymers, and thereby the charge migration is encouraged by the appearance of shallow trap.