Polypropylene (PP)-based nanocomposite is a promising insulation material for recyclable high-voltage direct current (HVDC) cables, where the coupling agent plays an important role. In this study, four silane coupling agents with different alkyl chain groups (methyl, propyl, octyl, and octadecyl) were used to surface-modify magnesium oxide (MgO) nanoparticles. The surface-modification effect on the electrical properties of PP/MgO nanocomposites was investigated. The results show that surface-modified nanoparticles introduce quantities of deep traps, whose quantity increases as the alkyl chain length increases. The similar tendency also occurs on DC volume resistivity. All these nanocomposites show remarkable space charge suppression ability and improved DC breakdown strength. Among them, the nanocomposites with octyl-modified MgO show the best electrical properties, which could be attributed to the introduction of a large quantity of deep traps. The work may give a reference for the selection of coupling agents in PP-based nanocomposite insulation material for HVDC cable.

中文翻译：

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MgO纳米颗粒的表面改性对聚丙烯纳米复合材料电学性能的影响

聚丙烯（PP）基纳米复合材料是用于可回收高压直流（HVDC）电缆的有希望的绝缘材料，其中偶联剂起着重要的作用。在这项研究中，使用具有不同烷基链基团（甲基，丙基，辛基和十八烷基）的四种硅烷偶联剂对氧化镁（MgO）纳米粒子进行表面改性。研究了表面改性对PP / MgO纳米复合材料电性能的影响。结果表明，表面改性的纳米粒子引入了深陷阱，其数量随着烷基链长度的增加而增加。在DC体积电阻率上也发生类似的趋势。所有这些纳米复合材料显示出显着的空间电荷抑制能力和改善的直流击穿强度。其中，具有辛基修饰的MgO的纳米复合材料显示出最佳的电性能，这可以归因于大量深阱的引入。这项工作可为选择用于HVDC电缆的PP基纳米复合绝缘材料中的偶联剂提供参考。