LDPE基复合材料电极对聚乙烯空间电荷注入的影响

发布时间：2018-01-20 01:04

本文关键词： 半导电电极空间电荷电阻率多省并醌类聚合物复合材料　出处：《青岛科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：半导电屏蔽层是高压直流电缆结构中的一个重要组成部分,它可以均匀绝缘层中的电场分布,防止电场畸变,减少电应力集中,从而提高绝缘层的击穿强度。半导电屏蔽层质量的好坏对高压直流电缆的使用寿命及其安全可靠性有重要影响,同时也是制约高压直流电缆快速发展的重要瓶颈。本文采用双辊开炼机混炼技术制备出导电炭黑(CB)与低密度聚乙烯(LDPE)的复合材料,以此作为制备高压直流电缆半导电屏蔽料的母料。通过密炼机混炼技术在母料中加入适量改性组分,以制备出性能较好的半导电电极,可作为高压直流电缆半导电屏蔽层。通过电阻率测试、拉伸测试、扫描电子显微镜观察、空间电荷测量等技术分析了所制备的半导电电极的性能。1.通过盐熔法制备多省并醌类(PAQR)聚合物,并把所制得的PAQR通过密炼机混炼加入到CB/LDPE母料中,制备半导电复合材料。采用PEA和TSC探究其对绝缘层空间电荷的抑制效果。结果表明:由PEA实验可知,PAQR含量较多时,有助于降低绝缘层空间电荷浓度,从而增强PAQR/CB/LDPE复合材料对空间电荷的抑制效果;由TSC实验可知,随着PAQR含量的增加,PAQR/CB/LDPE半导电电极对绝缘层的空间电荷的抑制作用越来越大。2.采用熔融共混及热压交联的方法制备了CB/LDPE/EVA半导电复合材料,对其拉伸强度、电阻率、交联度、热老化、热延伸及毛细管流变的性能进行了测试。结果表明:随着EVA含量的增加,CB/LDPE/EVA体系的断裂伸长率增加,但拉伸强度有所下降;在热延伸测试方面,其结果达到国家标准要求;通过毛细管流变测试发现,CB/LDPE/EVA体系拥有较低的剪切粘度,且毛细管挤出的试样表面达到了超光滑的水平,通过对比发现其综合性能已经接近于进口的高压直流半导电屏蔽料。3.本文还探究了在CB/LDPE/EVA体系中,CB含量的变化对半导电电极的电阻率的影响以及对绝缘层空间电荷的屏蔽效果。结果表明:半导电电极中CB含量增加时,电阻率降低,当CB含量超过25%后,电阻率减小不明显,表明试样在该CB比例下已接近过导电电阻的逾渗值;空间电荷测试时,半导电电极CB的含量增加时,绝缘层的空间电荷含量先增加后减小。
[Abstract]:Semi-conductive shielding layer is an important part of HVDC cable structure. It can evenly distribute electric field in insulation layer, prevent electric field distortion and reduce electric stress concentration. In order to improve the breakdown strength of insulation layer, the quality of semi-conductive shielding layer has an important impact on the service life of HVDC cable and its safety and reliability. At the same time, it is also an important bottleneck restricting the rapid development of HVDC cables. In this paper, the composite materials of conductive carbon black (CBB) and LDPE (low density polyethylene (LDPE)) have been prepared by using the technology of two-roller opener mixing. It is used as the master batch for preparing HVDC cable semi-conductive shielding material. Through mixing technology of mixer, a suitable amount of modified component is added to the master batch to prepare semi-conductive electrode with better performance. Can be used as high voltage DC cable semi-conductive shielding layer. Through resistivity testing, tensile testing, scanning electron microscope observation. The properties of the prepared semiconductive electrode were analyzed by space charge measurement. 1. The polyquinone PAQR polymer was prepared by salt melting method. The prepared PAQR is added to the CB/LDPE masterbatch by mixing with a mixer. PEA and TSC were used to study the inhibition effect of semiconductive composites on the space charge of insulating layer. The results showed that when the content of PAQR was higher, the results showed that the content of PAQR was higher. It is helpful to reduce the space charge concentration of the insulating layer, so as to enhance the space charge suppression effect of PAQR/CB/LDPE composite. According to TSC experiment, with the increase of PAQR content. The effect of PAQR/CB/LDPE semiconductive electrode on the space charge of insulating layer is increasing. 2. The CB/LDPE/EVA semiconductive complex was prepared by melt blending and hot pressing crosslinking. Composite material. The tensile strength, resistivity, crosslinking degree, thermal aging, thermal extension and capillary rheology were tested. The elongation at break of CB/LDPE/EVA system increased, but the tensile strength decreased. In the aspect of thermal extension test, the results meet the requirements of national standard. The capillary rheological test showed that the CBR / LDPE / EVA system had low shear viscosity and the surface of the sample extruded by capillary reached the level of super smooth. By comparison, it is found that its comprehensive performance is close to that of imported HVDC semi-conductive shielding material. 3. In this paper, we also explore the CB/LDPE/EVA system. The effect of CB content on the resistivity of semiconductive electrode and the shielding effect on the space charge of the insulating layer. The results show that the resistivity decreases with the increase of CB content in the semiconductive electrode. When the CB content exceeds 25%, the resistivity decreases little, indicating that the percolation value of the superconductive resistance is close to that of the sample at the CB ratio. When the content of CB in semiconductive electrode increases, the space charge content of insulating layer first increases and then decreases.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ325.12;TB332

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