Electrical Aging Properties of Polypropylene and Its Polyolefin Elastomer Composites

Polypropylene (PP) has great electric insulation performance and it is environmentally friendly, which makes it has a great potential to be used as the main insulation for HVDC cables. Adding elastomers is a common way to improve its flexibility, which may bring variation of material structure, thus influencing the electric performance. In this work, the electrical aging properties of polypropylene and its polyolefin elastomer composites were obtained. Polypropylene polyolefin elastomer (POE) composites were made with 20, 30, 40, 50, 60wt% of POE content. The breakdown strength, conductivity and electrical aging lifetime of PP/POE composites with different POE contents were tested. The ageing lifetime of PP/POE composites were tested with step-stress method, and the ageing parameter of inverse power law is calculated. The results show that with the increase of POE content, the breakdown strength of most PP-POE composites decreases. But the 40wt% PP/POE composites have the highest breakdown strength among all the PP-POE composites. The current density and the aging life have similar trends with the BD strength. The conductivity increases with the increase of electric field, and the conductivity of pure PP are lower than that of PP/POE composites. Step-stress tests shows that the total aging time decreases with the increase of POE content. At low field strength, the 40wt% PP-POE composites have a longer aging lifetime than other composites. The 40wt% PP-POE composites show the best electrical properties under DC voltage among all the composites.