Effect of Metal Ash on Dielectric Properties of Polypropylene for Film Capacitor Under Electro-Thermal Aging

Polypropylene (PP) is affected by the complex stresses such as electricity and heat for a long time in practical application, and the dielectric breakdown properties often decrease, which significantly lessens the service life of metalized film capacitors. The long-term stability of dielectric materials depends on the process parameter. In this paper, PP samples are prepared with various ash content, and the electrothermal aging test is carried out. The results suggest that after aging, the breakdown strength of the samples with high ash content indicates a reduction of 10.9%. In contrast, the breakdown strength of low ash content PP samples exhibits a decline of merely 3.8%. The matal ash within PP matrix generates initial free radicals during the process of aging degradation under the electrothermal field and catalyzes the decomposition of hydroperoxides to promote the aging reaction process. The research results provide guidance for enhancing the long-term operation performance of PP.