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为开发新型的可回收直流电缆绝缘材料，在对聚丙烯(polypropylene，PP)作为高压直流电缆绝缘材料可行性研究的基础上，对纳米MgO/PP复合材料的微观形貌与结构、热性能、空间电荷和直流击穿特性进行了详细研究。研究了纳米MgO含量对PP微观形貌与结构、热性能、电气性能等特性的影响，并通过测试电荷陷阱能级和密度分布解释了纳米MgO调控PP电气性能的机理。研究结果表明：纳米MgO添加不会明显改变PP的结晶度、晶型、熔融温度等参数，纳米MgO/PP复合材料依然保持了PP优良的热性能，且复合材料的热分解起始温度相对于 PP 略有提高。纳米 MgO颗粒的加入可以明显抑制PP中同极性电荷注入，减少空间电荷积聚。添加3 phr纳米MgO颗粒的复合材料具有最高的直流击穿强度，相对于纯PP增加了29.3%。热刺激电流测试结果表明纳米MgO添加可增加深陷阱密度，在电极附近形成屏蔽层并降低载流子迁移率，从而抑制同极性电荷注入并提高直流击穿场强。通过研究纳米 MgO 颗粒调控 PP的微观结构、热性能和电气性能的规律，可以为新型可回收直流电缆绝缘材料的开发提供参考。“,”Recently, polypropylene (PP) is considered as the potential recyclable HVDC cable insulation material. MgO nanoparticles were introduced into PP to tailor the properties of PP so as to make it more capable for HVDC cable insulation application. We focused on the micro morphology and structure, thermal properties, space charge accumulation and DC electric breakdown strength of the MgO/PP nanocomposites as well as the effect of MgO nanoparticles on these properties of PP. The mechanism of space charge suppression and breakdown strength enhancement in MgO/PP nanocomposites was explained by measuring the depth and density of the charge traps. The results indicate that the introduction of MgO nanoparticles has little effect on the crystallinity, crystal structure and melting temperature of PP and the good thermal properties of PP remain in MgO/PP nanocomposites. Inclusion of MgO nanoparticles obviously suppresses homocharge injection and reduces space charge accumulation. MgO/PP nanocomposite with 3 phr MgO nanoparticles exhibits the highest DC breakdown strength, which is 29.3 % higher than that of pure PP. The results of thermally stimulated current show that deep traps increase in MgO/PP nanocomposites, which would suppress charge injection and decrease charge carrier mobility. The effect of MgO nanoparticles on the properties of PP is established, which provides a reference for the design and development of recyclable HVDC cable insulation material.