Thermal and Dielectric Properties of Thermally Aged Polypropylene/Calcium Carbonate Nanocomposites

This paper reports on the effects of aging on thermal, chemical, and dielectric properties of unfilled polypropylene and polypropylene nanocomposites containing 5 wt% of surface-modified calcium carbonate nanofiller. The evaluated samples were prepared using a melt blending technique. Then, a hydraulic laboratory press was used to obtain a thin film sample. Three different aging conditions were considered, namely, unaged (as reference), and aged at 110 °C and 140 °C. The evaluated samples were then characterized using differential scanning calorimetry and Fourier transform infrared spectroscopy for thermal and chemical analyses, respectively. Meanwhile, the dielectric strength was determined based on DC electrical breakdown tests. The experimental results show that aging the samples at 140 °C changed the thermal behavior of all evaluated samples. Specifically, the melting temperature increased when the sample was aged at 140 °C. Of note, the DC breakdown strength of unfilled polypropylene reduced significantly after aging at 140 °C when compared to polypropylene nanocomposites.