Effects of atmospheric pressure on tracking failure of gamma-ray irradiated polymer insulating materials

With the increasing application of electric and electronic devices in space and nuclear power stations, the polymer insulation materials are inevitably exposed to various kinds of environments. As technology advances, increasing demands on the reliable operation under various operating and environmental conditions are made on materials and components. Therefore, it is important to investigate the influence of radiation on polymeric insulating materials used under the combined environments. This paper describes the effects of atmospheric pressure and gammaray irradiation on tracking failure of polybutylene naphthalate (PBN), polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) by applying a DC pulse voltage. PBN, PET and PBT were irradiated in air up to 100 kGy and then up to 1000 kGy with a dose rate of 10 kGy/h by using a ⁶⁰Co gamma-source. The effects of total dose of irradiation and atmospheric pressure on the time to tracking failure and discharge quantity were discussed. Obtained results show that, with increasing the total dose, the time to tracking failure increased with PBN and PET, but decreased with PBT. With decreasing the atmospheric pressure, the time to tracking failure increased with PBN, PET and PBT. While increasing the total dose, the discharge quantity decreased with PBN and PET, but increased with PBT. With decreasing the atmospheric pressure, the discharge quantity increased with PBN and PET, but decreased with PBT. The experimental results suggest that the chemical structure of the polymeric insulating materials plays a main role in the result of radiation reaction, which is related to cross-linking and degradation reaction.