In this work, the space charge behavior and breakdown strength of polypropylene (PP)/ultralow density polyethylene (ULDPE) blends and three different radical scavenger modified composites are performed at 30, 60 and 90 °C. The trap distribution in the radical scavenger and the composites are investigated based on quantum chemistry calculation and isothermal discharge current test. The results show that, 0.3 wt% addition of radical scavenger has little effect on the thermal and mechanical property of the composites. The radical scavenger can introduce traps with different energy levels, which has greatly inhibited the space charge accumulation aggravated by the increasing temperature in the PP/ULDPE (PU) blends. Although the overall breakdown strength of the samples decreases with the rise of temperature, the performance of radical scavenger modified composites show the best, which suggests a great correlation with the traps they introduce, the molecular structure and chemical reaction of the additives themselves. The PP/ULDPE blends with 0.3 wt% C944 exhibit great potential for HVDC cable insulation.

中文翻译：

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自由基清除剂对高压直流电缆绝缘用PP/ULDPE复合材料空间电荷积累的影响

在这项工作中，聚丙烯 (PP)/超低密度聚乙烯 (ULDPE) 共混物和三种不同的自由基清除剂改性复合材料的空间电荷行为和击穿强度在 30、60 和 90 °C 下进行。基于量子化学计算和等温放电电流测试研究了自由基清除剂和复合材料中的陷阱分布。结果表明，0.3 wt%的自由基清除剂对复合材料的热力学性能影响不大。自由基清除剂可以引入不同能级的陷阱，极大地抑制了 PP/ULDPE (PU) 共混物中因温度升高而加剧的空间电荷积累。虽然样品的整体击穿强度随着温度的升高而降低，自由基清除剂改性复合材料的性能表现最好，这表明与它们引入的陷阱、分子结构和添加剂本身的化学反应有很大的相关性。含有 0.3 wt% C944 的 PP/ULDPE 混合物在 HVDC 电缆绝缘方面表现出巨大的潜力。