Physical Mechanism of Breakdown Failure in Polymer Composites with Various Filler Loading

Dielectric polymer materials consisting of zinc sulfide nanoparticles (ZnS_nps) and poly(vinylidene fluoride) (PVDF) were prepared by a solution-casting process. The introduction of low filler loading results in obviously improved breakdown strength and energy density in comparison with pure PVDF, while the breakdown strength sharply becomes weak in the case of high filler loading. Based on the multi-core model, the electric double layer theory as well as the physical model we built, we propose that the insulation and charge distribution of the composites are regulated by the inter-fillers distance between neighboring fillers, resulting in the redistribution of the internal electric filed direction and the increase or decrease of the internal electric filed strength in the applied electric filed.