Aging-Resistant Breakdown Performance of Polypropylene Nanodielectrics

The current work discusses the effects of vacuum and oxidative aging at
$110~^{\circ }$
C on the direct current breakdown performance of pure polypropylene (PP) and PP nanodielectrics having 1 wt%, 2 wt%, and 5 wt% of magnesium aluminate, calcium carbonate, and surface-treated calcium carbonate nanoparticles. The results show that aging pure PP under vacuum changes the structure of the material, with the breakdown performance of pure PP consequently being reduced by 13%. Meanwhile, aging pure PP in circulating air causes the breakdown performance to reduce by as much as 29%, due to both structural and chemical changes within the material. In contrast, all the nanodielectrics experience much less detrimental effects on the breakdown performance even after thermo-oxidative aging, with the most substantial reduction being almost half that of the pure PP. Possible mechanisms governing changes in the breakdown performance, especially under thermo-oxidative aging, are discussed. The role of the nanoparticles in preserving the breakdown performance of the nanodielectrics against thermo-oxidative aging is particularly highlighted.