聚酰亚胺高温裂解机理的反应分子动力学模拟

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摘要聚酰亚胺（PI）由于其优异的绝缘性能,在固态变压器、变频调速电机等电力设备中得到广泛应用,而高温下化学键断裂是其绝缘失效的主要原因。基于ReaxFF的分子模拟方法,对PI分子模型进行反应分子动力学模拟,从原子层面揭示其高温裂解机理。以聚合度为4的PI分子为例,应用基于反应力场（ReaxFF）的反应分子动力学模拟方法对高温下PI的初始裂解、裂解过程中微观动态反应路径以及主要产物形成机理进行了模拟分析,得出PI高温下绝缘失效微观机理。结果表明：PI分子初始断键为酰亚胺环上C-N键,连接两苯环的C-N键断裂是PI分子主链断裂的主要原因;CO₂和CN是PI高温裂解的主要产物,CO₂与CN的形成均与酰亚胺环中的C-N键断裂有关;主链断裂引起的聚合度减小和酰亚胺环断裂产生的CO₂等小分子物质共同导致PI高温下绝缘失效。

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关键词 ：聚酰亚胺, 反应力场, 高温裂解, 微观机理, 反应分子动力学, 化学键断裂

Abstract：Polyimide, due to its excellent insulation properties, has been widely used in solid state transformers, frequency conversion motors and other electrical devices, whereas the cleavage of chemical bonds under high temperature is the main reason for the insulation failure. In this paper molecular simulation method based on reactive force field (ReaxFF) is introduced to carry out reactive molecular dynamics simulation on PI molecular models and to investigate its pyrolysis mechanism at high temperature in the atomic level. Polyimide with 4 monomers is taken as the example to simulate and analyze the initial pyrolysis mechanism, micro dynamic reaction paths during the whole process, the formation mechanism of main products. The microscopic insulation failure mechanism under high temperature is then obtained. The results indicate that initial breaking bond is the C-N bond on the imide ring, and the cleavage of C-N bond connecting two benzene rings is the main reason for PI main chain scission. CO₂ and CN are the major products of PI pyrolysis, and their formations are both associated with the cleavage of C-N bond on the imide ring; the reduced degree of polymerization of PI main chain, CO₂ and other small molecules generated by the scission of imide ring jointly lead to the insulation failure of PI at high temperature.

Key words： Polyimide ReaxFF high temperature pyrolysis microscopic mechanism reactive molecular dynamics the cleavage of chemical bonds

收稿日期: 2014-07-28 出版日期: 2016-07-12

PACS:

TM215.1

基金资助:国家高技术研究发展计划（863计划）（2012AA052701）,国家自然科学基金（51477051）和北京自然科学基金（3142018）资助项目

作者简介: 鲁旭男,1990年生,硕士研究生,研究方向为固态变压器绝缘局部放电检测。E-mail: 1193448568@qq.com;李庆民男,1969年生,教授,博士生导师,研究方向为高电压与绝缘技术等。E-mail: lqmeee@ncepu.edu.cn

引用本文:

鲁, 旭, 韩, 帅, 李庆民, 黄旭炜, 王学磊, 王高勇. 聚酰亚胺高温裂解机理的反应分子动力学模拟[J]. 电工技术学报, 2016, 31(12): 14-23. Lu Xu, Han Shuai, Li Qingmin, Huang Xuwei, Wang Xuelei, Wang Gaoyong. Reactive Molecular Dynamics Simulation of Polyimide Pyrolysis Mechanism at High Temperature. Transactions of China Electrotechnical Society, 2016, 31(12): 14-23.

链接本文:

https://dgjsxb.ces-transaction.com/CN/Y2016/V31/I12/14

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