Effect of gamma-ray irradiation on electrical conductivity of polypropylene composite for nuclear cable insulation

In this paper, the effect of gamma-ray irradiation on the electrical conductivity of polypropylene (PP) composites has been studied. The samples are prepared using PP and styrene-ethylene-butylene-styrene elastomer with contents ranging from 0 wt% to 50 wt%, and exposed to Cobalt-60 gamma irradiation, with a dose from 0 to 250 kGy. Electrical conductivities at different temperatures and trap distributions are measured to observe the deterioration of insulation performance. The microstructure of the sample is estimated using differential scanning calorimetry, X-ray diffraction, thermogravimetric analysis and a scanning electron microscope. The obtained results demonstrate a correlation between the increase in electrical conductivity and the elevation in both total dose and temperature. At 250 kGy, the trap distribution tends to become shallower, accompanied by a decrease in crystallinity, melting and decomposition temperatures of the sample. The PP composite exhibits better stability against irradiation and thermal effects, primarily due to the cross-linked structures formed by irradiation.