热处理工艺对聚乙烯醇力学性能影响的分子模拟研究

Effect of heat treatment on mechanical properties of polyving akohol by molecular dynamics simulation

摘要:

为了研究不同热处理工艺对聚乙烯醇力学性能的影响，使用Build polymers命令构建了链节数为100的1,3-乙二醇高分子链，采用Amorphous Cell模块将优化好的链段结构构建在三维周期边界下，得到聚乙烯醇的结构模型．采用COMPASS力场，取NVT系综，分别在363K、373K、383K和393K温度下进行分子动力学计算，以模拟不同的热处理温度；取冷却速率分别为17K/600ps和5K/600ps，以模拟快速冷却和缓慢冷却对聚乙烯醇力学性能的影响．结果表明，与快速冷却相比，缓慢冷却所得聚乙烯醇刚性减小，弹性伸长增加，延展性增强，力学性能得到改善．373K热处理温度下所得PVA的泊松比和柯西压最大，弹性伸长最好，延展性最强，力学性能最佳．

Abstract:

In order to study the effect of heat treatment on mechanical properties of polyving akohol (PVA), the command of Build polymers was used to construct 1,3-ethylene glycol polymer chain with 100 monomeric units. The module of Amorphous Cell was applied to put the optimized chain segment into the three dimensional periodic boundary. And the structure model of PVA was obtained. From the temperature 363K to 393K with the increase step of 10K, the molecular simulation was applied to investigate the effect of temperature on mechanical properties in NVT ensemble using COMPASS force field. The cooling rates of 17K/600ps and 5K/600ps were set to simulate the effect of cooling rate on mechanical properties. The results show that mechanical performance of polyving alcohol by slow cooling process is improved; as the rigidity decreases, the elastic elongation and the ductility increase. The mechanical performance of polyving alcohol by heat treatment temperature of 373K is the best, i.e., the Poisson’s ratio and Cauchy pressure are the largest, and the elastic elongation and the ductility are the best.