Polypropylene has excellent potential as a thermoplastic insulation material for HVDC cable, while its mechanical property and aging problem limit its engineering application. In this work, isotactic polypropylene (iPP) was blended with the polyolefin elastomer (POE), and the blends were thermally aged at 130 °C for various periods (up to 200 h). Taking pure iPP for a reference, the elongation at break of iPP/POE increased by 54.8%, the elastic modulus decreased by 42.5%, and the low-temperature brittleness decreased from −5 °C to −32 °C. During the 60 min polarization process of −100 kV/mm, the electric field distortion of pure iPP changed from 2.5% to 11.3% after thermal aging for 200 h, while that of iPP/POE just changed from 2.2% to 6.2%. The carrier mobility of both iPP and iPP/POE increased after thermal aging, and the carrier mobility of the latter increased by about two orders of magnitude. Combined with the results of thermally stimulated discharge current, iPP/POE was found to bring in more trapping center due to the newly generated interface between POE and iPP, which contributes to a smaller conduction current. This work provides insight into the thermal aging effects of polypropylene composite insulation for HVDC power cables.

聚丙烯作为高压直流电缆的热塑性绝缘材料具有极好的潜力，但其力学性能和老化问题限制了其工程应用。在这项工作中，全同立构聚丙烯 (iPP) 与聚烯烃弹性体 (POE) 共混，共混物在 130 °C 下热老化不同时间（最多 200 小时）。以纯iPP为参考，iPP/POE的断裂伸长率提高54.8%，弹性模量降低42.5%，低温脆性从-5℃降低到-32℃。在-100 kV/mm的60 min极化过程中，热老化200 h后，纯iPP的电场畸变从2.5%变为11.3%，而iPP/POE的电场畸变仅从2.2%变为6.2%。热老化后 iPP 和 iPP/POE 的载流子迁移率均增加，并且后者的载流子迁移率增加了大约两个数量级。结合热激发放电电流的结果，发现iPP/POE由于POE和iPP之间新生成的界面而带来更多的俘获中心，这有助于更小的传导电流。这项工作提供了对高压直流电力电缆聚丙烯复合绝缘材料的热老化效应的深入了解。