梳形聚合物在启动剪切下的分子动力学模拟研究  

Molecular Dynamics Study of Comb Polymer Melts under Start-up Shear

作　　者：王栋栋 徐晓雷[2] Dong-dong Wang;Xiao-lei Xu(College of Materials Science and Engineering,Jilin University,Changchun 130025;State Key Laboratory of Polymer Physics and Chemistry,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences,Changchun 130022)

机构地区：[1]吉林大学材料科学与工程学院,长春130025 [2]高分子物理与化学国家重点实验室,中国科学院长春应用化学研究所,长春130022

出　　处：《高分子学报》2022年第12期1543-1551,共9页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号21873092,21790341)资助项目.

摘　　要：采用非平衡分子动力学模拟方法研究了接有较短支链的非缠结梳形聚合物熔体对启动剪切流的响应,并与线形聚合物进行了比较.模拟发现,对不同的剪切强度,接有较短支链的非缠结梳形聚合物熔体的应力-应变响应与线形聚合物的变化趋势基本相同,仅在数值上存在差异.此外,进一步研究了梳形聚合物在启动剪切下的结构变化.结果表明,与梳形聚合物的主链相比,短支链在启动剪切下的拉伸较为微弱,且对非缠结梳形聚合物流变行为的影响较弱,致使梳形聚合物在启动剪切场下的性质与线形聚合物相似.The stress and structural behaviors of non-entangled comb polymer melts under start-up shear flow were studied by molecular dynamics simulations,and compared with those of linear polymer.It is found that the stress-strain response of the unentangled comb polymer with short branched chain is almost the same as that of the linear polymer under different shear strengths,and only the numerical difference exists.Under weak shear strength,the stress reaches the platform value after short temporary increase,and there is no stress overshoot behavior.Under strong shear strength,the stress first increases rapidly and then decreases to the plateau value.In this process,there is an overshoot peak.In addition,we further studied the structural properties of comb polymers under start-up shear.Under weak shear strength,the main chain of comb polymer has only slight deformation and orientation and the branched-chain is not basically stretched.Under strong shear strength,the main chain of comb polymer is strongly stretched,but the branch chain still has no obvious change.The results show that compared with the main chain of comb polymer,the branched chain is slightly stretched under start-up shear,which indicates that the influence of branched chain on the rheological behavior of non-entangled comb polymer is weak,so that the properties of comb polymer under start-up shear are similar to those of linear polymer.The simulation results in this paper will help to understand the macroscopic mechanical properties and microstructural changes of comb polymer systems,which are of great significance for designing new polymer materials with desired properties.

关 键 词：梳形高分子 分子动力学模拟 启动剪切 

分 类 号：O631.2[理学—高分子化学]