Enhanced Dielectric Properties of Polypropylene Film by Multilayered Structural Design for Power Capacitor

In this paper, multilayered structural design is proposed for improving the dielectric performance of polypropylene (PP) film for power capacitor. The maleic anhydride-grafted polypropylene (MA-g-PP) and tris (4-aminophenyl) amine (TAPA) are selected as additives. The results show that the composite film with PP/TAPA layer close to anode and PP/MA-g-PP layer close to cathode exhibits the best dielectric properties. The leakage conductivity drops by 87.9% at 30 °C and declines by 94.9% at 115 °C. The breakdown strength is improved by 12.9% at 30 °C and enhanced by 19.9% at 115 °C. The simulation results of electrostatic potential and molecular orbital indicate that the MA-g-PP and TAPA could capture free electrons and free holes injected from the electrodes respectively, thereby blocking the charge transport path. The multilayered structural design leads to the carriers accumulating in the outer layers, and the reverse electric field formed reduces the possibility of carriers entering the dielectric through the injection barrier. This method supplies a reference for improving the dielectric properties of PP films, which provides theoretical guidance for surface modification and additive selection.