Effects of thermal aging on structure and dielectric properties of polypropylene/calcium carbonate nanocomposites

This paper reports on an investigation of the effect of thermal aging on the structure and dielectric properties of unfilled polypropylene (PP) and PP nanocomposites containing 1 wt%, 2 wt%, and 5 wt% of calcium carbonate (CaCO3) nanofiller. Three different aging temperatures were considered, i.e., 20°C (unaged), 110°C, and 140°C. After aging, the dielectric strength of the samples was tested by means of DC breakdown testing. The results showed that, although the breakdown strength of PP nanocomposites was lower than that of unfilled PP before aging, the reduction in DC breakdown strength of PP nanocomposites was less pronounced compared with unfilled PP after aging. This indicated that the DC breakdown property of PP nanocomposites was less susceptible to thermal aging