ポリエチレンの耐トラッキング性に及ぼすγ線照射及び気圧の影響

抄録

Division of Electronic and Information Engineering, Tokyo University of Agriculture and Technology Tracking resistance of insulating materials has been studied by many investigators with a test method of the IEC Publ. 112. The effect of different parameters is still far from being well understood. These investigations are further enhanced due to the increasing of organic insulating materials being used in the lower atmospheric pressure and radiation environments of space and nuclear power facilities. This paper presents a study on effects of γ-rays irradiation and lower atmospheric pressure on tracking resistance of polyethylene by use of the IEC Publ. 112 method. Polyethylene samples which were irradiated in air until 1×10⁷R and 1×10⁸R with dose rate of 10⁶R/hr using ⁶⁰CO γ-source have been employed. The total dose effect on the tracking, namely on the weight loss and erosion depth have been studied under combined conditions. As the total doses are increased, the weight loss and maximum erosion depth decreases, and the rate of reduction increases with decreasing pressure in the investigated range of 1007hPa to 500hPa. The effects of gamma-rays irradiation are determined due to radiation-induced cross-linking. In this case, as the atmospheric pressure is reduced, the tracking resistance decreases. It is considered this is due to the increasing residual carbon on the samples surface.