Effect of Antioxidant Grafting on the Dielectric Properties of Polypropylene Insulation

This paper investigates the effect of melt radical graft modification of the hindered phenolic antioxidant (AO3052) on the insulating dielectric properties of polypropylene (PP). Conductivity and breakdown characteristics of grafted PP with varying antioxidant contents are examined. The results indicate that antioxidant grafting enhances the sensitivity of conductivity to temperature. The DC and aging breakdown strengths of PP grafted with different antioxidant contents are analyzed, and 0.5 wt% antioxidant can improve the DC breakdown strength of PP at 90 °C by 31.3% and improve the aging breakdown strength at 90 °C by 36.1%. Through trap distribution and energy band structure analysis, it is inferred that antioxidant grafting modification introduces additional local energy levels and potential traps in the forbidden bands of PP, thereby inhibiting charge transport.