Improved Breakdown Strength of Polypropylene Film by Introducing Terephthalaldehyde/PP Layer for Power Capacitors

In this paper, terephthalaldehyde/PP layer is introduced for improving the breakdown strength of polypropylene (PP) films for power capacitors. The length of alkoxy group is regulated to explore the promotion effect of terephthalaldehyde. The results indicate that when the number of carbon atoms reaches 8, the leakage conductivity decreases by 92.1% at 30 °C and declines by 95.9% at 125 °C. The charge accumulation rate K decreases from 1.74 to 1.18 at 30 °C and declines from 2.48 to 1.33 at 125 °C. The DC breakdown strength is enhanced by 19%-25%, and the energy density is improved by 68%-70%. The accumulation of holes in the functional layer could suppress the charge injection from the anode and the alkoxy chain growth could enhance the ability of free holes capturing. This method provides a feasible idea to obtain the film with better insulation performance from the perspective of molecular and charge migration.