基于ReaxFF的聚异丁烯高温裂解机理及影响因素研究

Study on Pyrolysis Mechanism and Influence Factor of Polyisobutylene Based on ReaxFF

作为高压电缆终端中的常用填充剂,聚异丁烯(polyisobutylene,PIB)的高温裂解机理尚不明晰。文中利用ReaxFF反应分子动力学软件,获得了聚异丁烯在2400 K和3000 K下的裂解产物及其生成路径。研究结果表明,3000 K下PIB高温裂解产物体积分数均高于2400 K,表明老化温度升高会加速PIB的裂解及各特征气体的生成,且H_(2)及CH4可作为PIB高温裂解的主要特征产物,并在473 K下开展了PIB热老化验证了数值模拟结果的有效性。同时,为探究影响PIB产气特性的关键因素,文中进一步开展了PIB的热—电联合老化实验和受潮PIB的热老化和热—电老化实验,气相色谱分析结果表明,火花放电时PIB中各气体组分体积分数最高,局部放电时次之,热老化时最低,并可将C_(2)H_(2)体积分数的变化量作为PIB发生放电故障的评估依据。特别地,不同受潮程度的PIB加速老化实验结果表明,水分将促进PIB的裂解,促进各特征产物的生成。文中可为进一步研究PIB的故障判据提供理论指导作用。

The pyrolysis mechanism of polyisobutylene(PIB)which is commonly used as a filler in high-voltage ca-ble terminals remains unclear.In this paper,the pyrolysis products of PIB under 2400 K and 3000 K conditions,and their generation paths are obtained by using ReaxFF molecular dynamics software.The study results show that the content of pyrolysis products of PIB at 3000 K is higher than at 2400 K,indicating that the aging temperature increase can accelerate the pyrolysis of PIB and the generation of characteristic gases,and H_(2)and CH4 can be used as the main characteristic products of PIB pyrolysis.The thermal aging of PIB is performed at at 473 K to verify the effectiveness of the numerical simulation results.Meanwhile,for exploring the key factors affecting the gas produc-tion characteristics of PIB,the thermal-electric combined aging experiment of PIB and thermal-electric aging asw ell as thermal-electric aging experiment of PIB affected by moisture are performed further.Gas chromatographic analysis results show that,in case of spark discharge,the content of each gas component in PIB is the highest,fol-lowed by partial discharge,and the lowest in case of thermal aging.The change of C_(2)H_(2)content can be used as the assessment basis of PIB discharge.In particular,the results of accelerated aging experiments of PIB with different degrees of moisture show that moisture would promote the pyrolysis of PIB and the formation of various characteris-tic products.This paper can provide theoretical guidance for further study of PIB fault criterion.