等规和嵌段聚丙烯的结构和性能

发布时间：2018-04-20 06:21

  本文选题：直流电缆 + 等规聚丙烯　； 参考：《高电压技术》2017年11期

【摘要】：聚丙烯(PP)不仅具有良好的电气性能和耐热性能,而且在寿命终止后可循环利用,有可能替代交联聚乙烯(XLPE)作为电缆绝缘材料。因而通过研究乙烯 丙烯嵌段共聚聚丙烯(EPC)和等规均聚聚丙烯(iPP)的微观结构、力学冲击强度和电学性能,探讨了EPC作为高压直流电缆绝缘材料的潜力。结果表明:iPP和EPC中只有α球晶,EPC中的α球晶较iPP中的小而密集,球晶之间没有明显的界面,球晶生长速度慢,但总结晶速度快。在不同温度下的非等温结晶过程中,EPC的结晶度低,熔点高。同时EPC中嵌段共聚的乙烯分子链片段形成橡胶态结构,显著提高了其抗冲击强度,低温脆化温度可达 57.3℃,远低于iPP的 5℃。EPC的常温体积电阻率和直流击穿场强低于iPP,但随温度升高其体积电阻率和击穿场强的稳定性高于iPP。在90℃,iPP和EPC的直流击穿场强分别下降了27%和21%,体积电阻率分别下降了128.8×10~(15)?·cm和52.5×10~(15)?·cm。在40 kV/mm下,iPP积聚的空间电荷密度约为EPC的3倍,因而EPC更适用于挤出型高压直流电缆绝缘料。EPC性能的改善均与其相态结构和微观晶体结构有关。
[Abstract]:Polypropylene (PP) not only has good electrical properties and heat resistance, but also can be recycled after the end of life. It may be used as a cable insulation material instead of XLPE. Therefore, the potential of EPC as insulation material for HVDC cables is discussed by studying the microstructure, mechanical impact strength and electrical properties of ethylene / propylene block copolymerized polypropylene (EPC) and isotactic polypropylene (IPP). The results show that only 伪 -spherulites in EPC and EPC are smaller and denser than those in iPP. There is no obvious interface between spherulites, and the growth rate of spherulites is slow, but the total crystallization rate is fast. In the process of non isothermal crystallization at different temperatures, the crystallinity of EPC is low and the melting point is high. At the same time, the block copolymerized segments of ethylene molecules in EPC formed rubber structure, which significantly improved its impact strength, and the embrittlement temperature reached 57.3 鈩，

本文编号：1776624