Effect of Gamma-Ray Irradiation on Aging Behavior of Pp Composites as Cable Insulation

Polypropylene (PP), characterized by remarkable temperature resistance and cost-effectiveness, emerges as a promising candidate for nuclear cable insulation. However, the application of PP is significantly constrained by its vulnerability to high-dose irradiation-induced degradation. In this paper, styrene-ethylene butadiene styrene block copolymer (SEBS) was added to PP. Bis(t-butyl peroxy isopropyl)benzene (BIBP) and Triallyl isocyanurate (TAIC) were respectively selected as crosslinking agents to prepare SEBS/PP composites, which were then irradiated by a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${ }^{\mathbf{6 0}} \mathbf{C o}$</tex> gamma source at doses from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{0}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{2 5 0}$</tex> kGy. The electrical conductivities and trap parameters of the samples were measured. The structural alterations were evaluated through differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) measurements to investigate the aging behaviors of composites. The results indicated that both the deep and shallow trap depth of each sample showed a downward trend with escalating total dose, while shallow trap density increased. The melting point and crystallinity of composites decreased, whereas conductivities increased. The dielectric properties of the samples with TAIC were better than those with BIBP, evidenced by lower conductivities. It is suggested that the aging of composites is closely linked to oxidation and degradation of molecular chain structures, and TAIC can show more prominent cross-linking effects to resist irradiation.