纳米碳化硅/低密度聚乙烯复合材料的空间电荷分布特性

Space Charge Distribution of Nano-SiC/Low Density Polyethylene Composite

空间电荷的积聚会引起局部电场的畸变,从而引起局部放电(PD)和电树枝的产生与发展,成为导致聚合物绝缘性能降低的重要因素。针对此问题,采用电声脉冲(pulsed electro-acoustic,PEA)法研究了利用不同偶联剂(包括KH-560偶联剂和A-171偶联剂)进行表面改性后的纳米SiC添加到低密度聚乙烯(LDPE)中所制备得到的SiC/LDPE复合材料的空间电荷分布。实验结果表明,纳米SiC粒子与LDPE本体之间的界面是陷阱的主要来源,添加纳米粒子对同极性电荷的注入具有一定的抑制作用;而偶联剂对陷阱的性质和能级有重要的影响,不同复合材料的空间电荷分布是不同的,KH-560SiC/LDPE复合材料中存在大量正极性亲和性的深陷阱,而A-171SiC/LDPE复合材料中则分布大量正极性亲和性的浅陷阱,从而影响载流子迁移,改变原有LDPE的介电性能。分析认为此现象源于不同偶联剂的分子结构差异,含有不对称侧链和端基的KH-560偶联剂更容易产生深陷阱,而含有烯烃结构的A-171偶联剂则容易产生浅陷阱。

Space charge accumulation will cause local electric field distortion,the emergence,and development of the partial discharge（PD） and electrical tree,which degrades the polymer insulation.Thus,by using the pulsed electro-acoustic（PEA） method,we study the space charge distribution in low density polyethylene（LDPE） which has nano-SiC modified with different coupling agent.The results show that the interface between the nano-SiC particles and the polyethylene body is the main source of charge traps,and adding nanoparticles has a certain inhibition of the homocharge injection from electrodes.Besides,the coupling agent has an important influence of the formation and properties of the charge traps,e.g.the A-171 SiC/LDPE produces more shallow energy traps with positive polarity tendency,but the KH-560 SiC/LDPE produces deep traps with negative polarity tendency.Therefore,the nano-particles will affect the carrier mobility of LDPE,and change its dielectric properties.It is concluded that this difference mainly comes from the different molecular structures of coupling agents,e.g.the KH-560 has asymmetric side chains and end groups but the A-171 has an olefin structure.