Aging Effects on Structure and Breakdown Properties of Polypropylene/Multi-Element Oxide Nanocomposites

This paper investigates the effects of thermal aging on unfilled polypropylene (PP) and PP containing 1 wt% of magnesium aluminate (MgAl
2
O
4
), calcium carbonate (CaCO
3
), and surface modified calcium carbonate (CaCO
3
T) nanofillers. Two different aging conditions were considered, i.e., unaged (20 °C) and aged (140 °C). The structures of the evaluated samples before and after aging were observed using scanning electron microscopy (SEM). In addition, thermal stability and electrical properties were evaluated by means of thermogravimetric analysis (TGA) and DC breakdown testing. The results showed that the structure of all investigated samples was less susceptible to thermal aging. Meanwhile, the thermal stability of the unfilled PP has reduced significantly than that of nanocomposites. Besides that, the electrical breakdown strength of both the unfilled PP and PP nanocomposites containing 1 wt% of MgAl
2
O
4
, CaCO
3
, and CaCO
3
T nanofiller has reduced compared to the respective unaged samples. Of note, nanocomposites were less susceptible to changes in DC breakdown strength after thermal aging.