摘要
低密度聚乙烯的分子结构是影响高压直流电缆电气性能的关键因素。本文选取了进口和国产的高压直流电缆用绝缘料,通过凝胶渗透色谱、红外光谱和核磁共振谱从结构上研究聚乙烯基料的分子量分布、碳碳双键含量和支化度;从宏观上分析材料的电气性能和加工流变性能,并探讨聚乙烯的结构特性对其电气和流变性能的影响机制。结果表明:进口绝缘料的分子量分布较窄,端基双键含量高,长链支化度高,在高温下的绝缘性能较好,50℃下的直流击穿场强比国产绝缘料高约36%,且在40 kV/mm直流场作用下其内部未发现异极性空间电荷。聚乙烯分子量分布窄,分子内部晶点(大分子或超大分子等杂质)较少,有助于抑制异极性空间电荷。聚乙烯支化度较高,分子链间缠结点较多,使得材料在高温下的稳定性较好。
The molecular structure of low density polyethylene(LDPE) is an important factor that affects the electrical properties of high-voltage direct current cables(HVDC). In this research, the HVDC cable insulation material made inside and outside China was studied, and the molecular weight distribution, the carbon-carbon double bond content, and branching degree of the LDPE material were investigated by gel permeation chromatography, infrared spectroscopy, and nuclear magnetic resonance spectroscopy, respectively. Besides, the electrical and processing rheological properties of the LDPE material were analyzed, and the influence mechanism of LDPE structure characteristic on their electrical and rheological properties was discussed. The results show that the samples made outside China have narrower molecular weight distribution, higher relative content of end-group bonds, and larger branching degree. Besides, the samples made outside China have better insulation properties at high temperature, their DC breakdown strength at50 ℃ are about 36% higher than that of the samples made inside China. Under the DC electrical field of 40 kV/mm, there is no heterocharge inside the samples made outside China. Generally, the LDPE with narrower molecular weight distribution has less crystallization points(including macromolecules and supermolecules), which is helpful to suppress the heterocharge. The LDPE with larger branching degree usually has more intermolecular entanglement points, which makes it have better stability at high temperature.
作者
李维康
祝文亲
张翀
闫轰达
李文鹏
陈新
钟力生
LI Weikang;ZHU Wenqin;ZHANG Chong;YAN Hongda;LI Wenpeng;CHEN Xin;ZHONG Lisheng(State Key Laboratory of Advanced Transmission Technology,Global Energy Interconnection Research Institute Co.,Ltd.,Beijing 102211,China;Petrochemical Research Institute,PetroChina,Beijing 102206,China;State Key Laboratory of Electrical Insulation and Power Equipment,Xi’an Jiaotong University,Xi'an 710049,China)
出处
《绝缘材料》
CAS
北大核心
2020年第7期74-82,共9页
Insulating Materials
基金
国家电网公司科技项目(SGGR0000DWJS1800786)。
