Enhanced Dielectric Performance of Polypropylene Film by Surfacing Grafting and Crosslinking for Metalized Film Capacitors

In this paper, the surface grafting and crosslinking modification method is proposed for enhancing the dielectric properties of polypropylene (PP) films for metalized film capacitors (MFCs). The results indicate that the leakage conductivity of the modified film is 1.05 × 10 ⁻¹⁶ S/m, exhibiting better resistance characteristics. The DC breakdown strength could reach 625.2 kV/mm, marking a notable 14.8% increase compared to the pure PP film. The surface grafting could lead to charge concentration at the electrode/film interface, which weakens the interfacial electric field and inhibits charge injection. Furthermore, the crosslinking reaction could enhance the entanglement of macromolecular chains, thereby changing the crystal morphology of PP and decreasing the migration rate of carriers. This method improves the dielectric properties of the capacitor film from the perspective of charge transport.