Due to the good electrical performance and high thermal stability, there is a tendency to develop the new generation of polymeric insulation materials based on polypropylene (PP). Compared with XLPE, PP is a thermoplastic polymer which can be recycled after use. However, the tertiary carbon structure on the side chain makes PP easier to be oxidized and degraded under high temperatures and high electric field. Nanocomposite technology can improve the electrical properties of polypropylene and reduce the damage of polypropylene under high electric fields. In this paper, the effects of octaphenyl polyhedral oligomeric silsesquioxane (OpPOSS) nanofillers on the electro-aging characteristics of PP are reported. Measurement techniques including thermally stimulated depolarization current (TSDC); scanning electron microscope (SEM); breakdown strength tests and conductivity tests, were used to understand the mechanisms by which the addition of OpPOSS influences the aging characteristics of PP. The lifespan of PP and OpPOSS/PP nanocomposites have been estimated by use of the Weibull distribution. As a results of this research work, the addition of OpPOSS nanofiller could improve the long-term performance of PP for HVDC applications.

electrical performance;thermal stability;polypropylene;HVDC insulation;electro-thermal aging;lifespan