Investigation on Insulating Degradation of Heat Resistant Organic Materials by Irradiation

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In this study, physicochemical and dielectric breakdown characteristics of heat resistant organic materials gamma ray-irradiated were investigated.Samples used are perfluoroalkoxy (PFA), fluorinated-ethylene-propylene (FEP), polyetheretherketone (PEEK) and epoxy resin (EPX). Irradiation was carried out by gamma ray (0.258kC/kg・h) in air at room temperature.From results of physicochemical analyses, it was found that the amount of free radicals of PFA and FEP increased at 0.01MGy irradiation and oxidation reactions occurred by chain scission. A structure of PEEK didn't change up to 5MGy irradiation.Dielectric breakdown characteristics of PFA and FEP films decreased with increasing irradiation dose, especially changed at 0.15MGy irradiation rapidly. But, those of PEEK film didn't change up to 5MGy irradiation. On the other hand, dielectric breakdown characteristics of EPX tended to decrease at 2MGy irradiation.Next, dielectric breakdown characteristics of PFA cable decreased rapidly at 0.2MGy irradiation, but, those of FEP cable didn't change up to 0.2MGy irradiation. Dielectric breakdown characteristics of PEEK cable didn't change up to 5MGy irradiation.Irradiation resistant characteristics of EPX existed between FEP and PEEK. Irradiation dose that dielectric breakdown characteristics of PFA and FEP cables (thickness : 0.5mm) decreased rapidly was high compared with PFA and FEP films (thickness : 50um). This fact indicates the depth of oxidation degradation is shallow from the surface of samples.