纳米氧化镁聚丙烯复合绝缘材料的制备及其性能

Preparation of MgO/Polypropylene Insulation Nanocomposites and Their Properties

与传统的电缆材料交联聚乙烯(XLPE)相比,聚丙烯(PP)不仅具有良好的电气性能,而且可循环利用,且其耐热性能好,因此受到研究者的广泛关注。故尝试选用聚丙烯作为基础树脂材料,同时探究添加纳米氧化镁(MgO)对聚丙烯绝缘性能的影响。选择嵌段共聚和均聚两种聚丙烯基础树脂材料,分别将质量分数为0.5%、1%、2%、3%的纳米氧化镁添加到PP中,综合不同样品的直流(DC)击穿场强等多因素,发现1%为纳米MgO的最佳添加量。再用两种不同的工序将质量分数为1%的纳米MgO和质量分数为5%的乙烯-辛烯弹性体(POE)加入到质量分数为95%的PP基体中,并与纯净的PP和PP与POE的共混物做对照。然后对样品的微观形貌、力学性能及电学性能进行表征。研究结果表明:纳米MgO加入到PP中,会起到异相成核剂的作用,减小PP内球晶的尺寸,且会诱导β晶生成;在PP中添加纳米MgO能大大降低其空间电荷密度,但对其力学性能影响不大;添加纳米MgO的PP直流击穿场强和直流叠加冲击电压与交联聚乙烯(XLPE)比较没有明显的差别。由此可知,可回收的热塑性聚丙烯高压直流电缆是未来高压直流电缆的一种新选择。

Compared with the traditional insulation materials such as cross-linked polyethylene （XLPE）, polypropylene （PP） is famous for its better recyclable and thermal properties, as well as good electrical performance. Therefore, selecting PP such as propylene-ethylene copolymer and homo-polypropylene as base resin materials, we studied the influence of adding nano magnesium oxide （MgO） on PP＇s insulation. First, we prepared a series of nano-composites with 0.5%, 1%, 2%, and 3% MgO contents, and tested the direct current （DC） breakdown strength of samples. According to the main instriation parameters such as DC breakdown strength, the optimum additive content of MgO is 1%. Second, 1% nano-MgO and 5% ethylene-octene elastomer（POE） were added to PP matrix through two different processes to compare the nanocomposites in the presence of pure PP and the blend of PP/POE. Finally, the microstructure, mechanical property and electrical property of all samples were characterized. Results show that nano-MgO, as heterogeneous nucleating agent, can reduce the size of sphaerocrystal and induce the generation of β-crystal in PP. Adding nano-MgO to PP hardly affects the mechanical property. However, it reduces space charge of PP greatly. There was no significant differences in DC breakdown strength and DC superimposed impulse voltage between PP and XLPE. Recyclable thermoplastic PP is a new option for HV-DC cable in the future.