Effect of Antioxidant Grafting on Conductivity and Carrier Migration Characteristics of Polypropylene Composite Cable Insulation

To investigate the effect of grafting modification on the carrier migration characteristics of polypropylene (PP) elastomer composite insulation, a composite insulation of antioxidant grafted modified PP blend thermoplastic elastomer is prepared. The evolution laws of direct current (DC) conductivity and DC integrated charge (DCIC-Q(t)) of the composite insulation are studied, and the influence mechanism of grafting modification on the distribution characteristics of charge traps is analyzed. Research has found that compared to unmodified composite insulation, graft modified composite insulation can reduce leakage current by 33.4% under high temperature and high electric field, increase the threshold field for charge injection by 30-50%, significantly reduce the accumulation of space charge, and increase the trap energy level, exhibiting stronger trapping of carriers. Through experiments and simulations, it was found that grafting not only introduced localized deep trap states in the energy levels of PP, increasing the trap density, but also enhanced the intermolecular interaction energy, thereby restricting carrier migration under high temperatures and high electric fields, ultimately improving the insulating performance of the material.