半导电屏蔽材料是制造高压电缆的关键组分,但仍存在电阻率高及其稳定性差难题.基于此,该文提出构筑双逾渗网络结构思路,选择乙烯-丙烯酸丁酯共聚物(ethylene-butyl acrylate copolymer,EBA)和低密度聚乙烯(low density polyethylene,LDPE)作为基体、导电炭黑(conductive carbon black,CB)作为导电填料制备半导电屏蔽材料,系统研究半导电屏蔽材料结构演变规律,评价半导电屏蔽材料结晶行为、电学性能、力学性能、表面光洁度等关键性能.实验结果表明:EBA与LDPE质量比为6:4时,半导电屏蔽材料内部形成双逾渗导电网络结构,相比于常规分布结构,其 23和90℃的体积电阻率分别降低46.7%和74.4%,对应的正温度系数(positive temperature coefficient,PTC)降低52.1%,表明具有良好的电阻率稳定性.此外,该半导电屏蔽材料还具有优异的力学性能和表面光洁度.该结果可为高压电缆半导电屏蔽材料开发提供一定理论基础与数据支撑.
Influence of Double Percolation Network of Semi-conductive Shielding Materials on Resistivity Stability of High Voltage Cable
Semi-conductive shielding materials are the key raw materials of high-voltage cables,but there are still problems of high volume resistivity and poor stability.Herein,we propose the idea of constructing double percolation network,semi-conductive shielding material is prepared by using low-density polyethylene(LDPE)and ethylene-butyl acrylate copolymer(EBA)matrix as polymer matrixes,and high-quality conductive carbon black(CB)as the conductive filler.The structure evolution law of the semi-conductive shielding materials is systematically studied,and the key properties,such as crystallization behavior,electrical properties,mechanical properties and surface finish,are evaluated.The experimental results show that when the mass ratio of EBA to LDPE is 6:4,double percolation network is formed inside the semi-conductive shielding materials.Compared with CB/EBA composites,the volume resistivity at 23 and 90℃decreases by 46.7%and 74.4%,respectively,and the corresponding positive temperature coefficient(PTC)is reduced by 52.1%.The results show that the semi-conductive shielding materials have good resistivity and stability when the mass ratio of EBA to LDPE is 6:4.At the same time,it has excellent mechanical properties and surface finish.This study provides a theoretical basis and data support for the development of semi-conductive shielding materials for high-voltage cables.
high voltage cablesemi-conducting shielding materialsdouble percolation networklow density polyethyleneethylene-butyl acrylate copolymer