Effect of Gamma-Ray Irradiation on Dielectric Properties of Polypropylene as Cable Insulation

Polypropylene (PP) is considered a good choice for nuclear cable insulation material for its high melting point and great dielectric properties. However, nuclear power cables need to withstand gamma-ray irradiation, and its effect on PP is not clear. In this paper, isotactic polypropylene (iPP), block polypropylene (bPP) and iPP/styrene ethylene butylene styrene (SEBS) elastomer blends were prepared and irradiated with the total doses of 0,500, and 1000 kGy. The chemical and dielectric properties of samples were studied by the Fourier transform infrared spectroscopy (FTIR) and isothermal surface potential decay (ISPD). The results showed that with the increase in total dose, the morphology of the sample turned curled and yellowing, the intensity of the carbonyl peak increased and the trap appeared to be shallower. It is indicated that the irradiation may accelerate the oxidation and the addition of SEBS elastomer is beneficial to improve the irradiation resistance of iPP.