热老化前后LDPE/SiO2纳米复合材料空间电荷积聚分析

Space charge accumulation behavior of Polyethylene/Silica Nanocomposites before and after thermal aging

在实际运行中,直流场强和热环境都会对聚乙烯电缆內空间电荷积聚行为产生影响,过量的空间电荷会威胁其绝缘性能,虽然纳米复合材料具备抑制空间电荷的能力,但对于热老化后其空间电荷的积聚特性仍有待进一步研究。采用电声脉冲法对热老化前后不同浓度的低密度聚乙烯(LDPE)/二氧化硅(SiO2)纳米复合材料內空间电荷的积聚行为进行分析。结果表明,热老化会降低电极注入势垒并产生随机分布的深陷阱和杂质,增加空间电荷积累。纳米引入的大量界面区域会产生均匀分布的深陷阱,并形成界面反电场,从而抑制载流子的运输和注入,且纳米粒子可以提高材料稳定性,提升电极注入势垒并延缓热老化进程。相比于纯LDPE,LDPE/SiO2材料在热老化前后都具有明显的抑制空间电荷的能力。

In practical operation, DC field strength and thermal environment can affect the accumulation of space charge in poly-ethylene cable. And excess space charge can threaten the insulation performance. Although nanocomposites can sup-press space charge, the space charge accumulation characteristics after thermal aging still need to be further studied. In this paper, the space charge accumulation behavior in low-density polyethylene (LDPE)/ silica (SiO2) nanocomposites with different SiO2 mass concentrations before and after thermal aging was studied by the pulse electro-acoustic meth-od. The results show that thermal aging reduces the electrode injection barrier and generates deep traps and impurities with random distribution, increasing the accumulation of space charge. Many interface regions introduced by nano-SiO2 generate deep traps with uniform distribution and form interfacial anti-electric field, inhibiting the transport and injec-tion of carriers. Moreover, nanoparticles can improve the stability of materials, thereby enhancing the electrode injection barrier and delaying the thermal aging process. Therefore, compared with pure LDPE, LDPE/SiO2 has the obvious ability to suppress space charge before and after thermal aging.