Abstract：Polyethylene terephthalate (PET) is used as an electrode coating in gas insulation lines (GIL) to reduce the threat of metal particles to GIL operation. PET will gradually age under the influence of electricity, heat and other factors, eventually leading to insulation failure. In this paper, the micro-dynamic reaction path and the main product formation process of PET at high temperature were analyzed via ReaxFF, and the microscopic mechanism of PET insulation failure at high temperature and high field strength were obtained. A large number of highly reactive ester groups in PET are prone to fracture under the action of electricity and heat, which in turn leads to a decrease in the degree of polymerization of PET and the resistance to field strength. In the thermal cracking, it produces a large number of terephthalate, C2H4 and other small molecules, in which the former is easily combined with hydrogen ions to form PTA. At higher reaction temperatures, terephthalate decarboxylation is enhanced and the rate of CO2 production is significantly accelerated. The main gas products such as C2H4, CO2 and CO are accumulated in the interior of PET to form micropores. The local discharge will easily occur in the micropores and eventually lead to the breakdown of PET due to insulation failure. The electro-cracking reaction of PET chains with different degrees of polymerization was simulated. The results show that, the molecules are polarized and the internal force is weakened under the action of the electric field force. The morphology is also destroyed, and the thermal stability and mechanical strength are decreased.
辛喆, 赵彤, 韩智云, 邹亮, 张黎. GIL中聚酯薄膜在电热作用下裂解机理的分子动力学模拟[J]. 电工技术学报, 2018, 33(22): 5196-5205.
Xin Zhe, Zhao Tong, Han Zhiyun, Zou Liang, Zhang Li. Molecular Dynamics Simulation of the Pyrolysis Mechanism of Polyester Films in Gas Insulation Lines Under Electrothermal Stresses. Transactions of China Electrotechnical Society, 2018, 33(22): 5196-5205.
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2018, Vol. 33 
