Dielectric properties of thermally aged polypropylene nanocomposites

Abstract

This article reports on an investigation into the effects of thermal aging on the structure and dielectric properties of polypropylene (PP) nanocomposites. Magnesium aluminate (MgAl2O4), calcium carbonate (CaCO3), and surface-modified calcium carbonate (CaCO3T) nanofillers have been added to PP and the resulting nanocomposites have been subjected to aging at 110 °C and 140 °C. The results show that unfilled PP experiences a 13% reduction in its dc breakdown strength after aging at 110 °C and that its dc breakdown strength reduces by 27% after aging at 140 °C. In contrast, the reduction in the dc breakdown strength of all investigated PP nanocomposites is much less pronounced than that of the unfilled PP after aging. Specifically, the dc breakdown strength of PP/MgAl2O4 nanocomposites, PP/CaCO3 nanocomposites, and PP/CaCO3T nanocomposites reduces by 8%, 14%, and 14%, respectively, after aging at 140 °C. Possible mechanisms affecting the dc breakdown strength of the unfilled PP and PP nanocomposites before and after aging are consequently discussed.