中文摘要：

以PU改性乙烯基树脂（polyurethane/vinyl ester resin,PU/VER）为研究对象,通过反应分子动力学（reactive force field,Reax FF）力场仿真分析,从原子层面揭示其在不同反应温度下的高温裂解微观特性.对含有1395个原子的体系进行仿真计算,该体系以不同的速度升温至2800~4800 K的反应温度.结果表明,PU改性所产生的O—O键最先断裂,将含C—N键的支链部分与主链分开;主链中氧桥键O—C在支链上C—N键断裂之后发生的断裂是乙烯基树脂主链断裂的主要原因,由此引发的链式反应最终导致高分子链解聚;位于主链端部的乙烯基（H2C=CH—）由于碳碳双键的解离能较高,其在3种主要的热解产物H2、CO2和C2H2的生成过程中均有参与.本文采用Reax FF动力学方法模拟得到的小分子气体产物及其生成路径与实际试验结果相一致,这说明Reax FF动力学方法是一种阐释有机高分子化合物热解化学反应机理的有效方法.

英文摘要：

Reactive force field （ReaxFF） molecular dynamics simulation was adopted to study the pyrolysis mechanism of polyurethane/vinyl ester resin （PU/VER） at an atomic level. The reaction systems, containing 1395 atoms,were simulated at various heating rates and temperatures,ranging from 100 K/ps to 500 K/ps and 2800 K to 4800 K respectively. The relevance between the simulation results and the experimental observations was also discussed. In the pyrolysis process,due to the initial dissociation of the PU-modified O--O bonds,the branched chains including C--N were separated from the main chains. Then the oxygen-bridge bonds in the main chains broke subsequently,which presented the primary cause of vinyl resin main-chain scission. Hence, the consecutive chain reaction would ultimately lead to the de-polymerization of the entire polymer structure. Because of intensive activity of the carbon-carbon double bonds,the vinyl （H2C ~-CH--） at the end of PU/ VER main chains was involved in the generation process of the final three dominant products, including hydrogen （H2）, carbon dioxide （CO2 ） and acetylene （C2H2 ）. Furthermore, the primary products and the corresponding generation paths of PU/VER pyrolysis extracted from the ReaxFF simulations coincided well with the experimental observations. The proposed research demonstrates that, the ReaxFF-based simulation methodology can provide deep insight into the chemical reaction mechanisms in polymer pyrolysis.