纳米粒子形貌对聚吡咯/LDPE纳米复合材料直流介电性能的影响

Influence of nanoparticle morphology on the direct current dielectric properties of polypyrrole/LDPE nanocomposites

为了研究不同微观形貌的纳米导电粒子对低密度聚乙烯(LDPE)直流介电性能的影响,本文采用软模板法制备了直径约100 nm的聚吡咯(PPy)纳米球和纳米线,并将其与LDPE熔融共混制备得到了PPy/LDPE纳米复合材料。利用扫描电子显微镜(SEM)观察了PPy纳米粒子的微观形貌及其在PPy/LDPE纳米复合材料中的分散结构,并测试了复合材料的结晶度、空间电荷分布、介电谱、不同温度下的直流电导电流及直流击穿强度等介电性能。结果表明:PPy纳米粒子的加入可以提高LDPE的结晶度,抑制LDPE中空间电荷的累积,降低其相对介电常数、直流电导电流和直流击穿强度,其中PPy纳米球的加入可在不同温度下使LDPE直流电导电流降低1个数量级以上,而对其直流击穿强度的影响较小,并且在较高温度下可将LDPE的直流击穿强度提升4.4%。PPy纳米球对LDPE绝缘材料直流介电性能的改善效果要优于PPy纳米线。

In order to study the effect of nano conductive particles with different microscopic morphologies on the direct current(DC)dielectric properties of low-density polyethylene(LDPE),polypyrrole(PPy)nanospheres and nanowires with a diameter of about 100 nm were prepared by soft template method,and melt blended with LDPE to obtain PPy/LDPE nanocomposites.The microscopic morphology of PPy nanoparticles and their dispersion structure in PPy/LDPE nanocomposites were observed by scanning electron microscopy(SEM).The crystallinity,space charge distribution,dielectric spectrum,and DC conductive current and DC breakdown strength of the composites at different temperatures were tested.The results show that the addition of PPy nanoparticles can improve the crystallinity of LDPE,inhibit the accumulation of space charges in LDPE and reduce the relative dielectric constant,DC conductive current and DC breakdown strength.The addition of PPy nanospheres can reduce the DC conductive current of LDPE by more than one order of magnitude at different temperatures,but has little effect on its DC breakdown strength,and can increase the DC breakdown strength of LDPE by 4.4%at a higher temperature.The improvement effect of PPy nanospheres on DC dielectric properties of LDPE insulation materials is better than that of PPy nanowires.