文章摘要
聚合物注塑成型保压冷却阶段分子演化机制
Molecular Evolution Mechanism of Polymer During Packing and Cooling Stage in Injection Molding
  
DOI:10.16865/j.cnki.1000-7555.2017.12.019
中文关键词: 聚丙烯  保压  冷却  分子链  取向
英文关键词: polypropylene  packing  cooling  molecular chain  orientation
基金项目:国家自然科学基金资助项目(51365038,51565034);江西省自然科学基金资助项目(20161BAB206123)
作者单位
喻 选, 辛 勇 南昌大学 机电工程学院 江西 南昌 330031 
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中文摘要:
      以等规聚丙烯(iPP)为例,构建含8条聚合度为2000的PP分子链团模型,基于分子动力学理论,研究了注塑成型充模流动后保压冷却阶段聚合物分子链团形态结构演化分子机制,得到聚合物在不同剪切条件下的瞬态结构及其演化规律。结果表明,剪切流动与保压冷却过程中分子链键长、键角等分子结构并不改变,所改变的仅仅是分子链团的聚集形态和运动状态,体系势能变化说明分子链团经过保压冷却后发生解取向。回转半径与均方位移结果表明,取向变形后的聚合物分子链团在保压冷却阶段不再迁移而相互分离,仅只在剪切终态位置发生弹性回复,且其前期流动时剪切速率越高,在保压冷却阶段弹性回复的程度越大。
英文摘要:
      In order to investigate the molecular evolution mechanism of polymer chains during packing and cooling stage, a PP model which contains 8 chains with polymerization degree of 2000 was constructed. Based on molecular dynamics theory, the transient structure of polymer chains and its evolution law were studied. The results show that no matter shearing flow or packing and cooling, the bond length and bond angle of polymer chains don’t get changed, what changed only is the aggregation and motion state. The change of potential energy indicates that the molecular chains tend to a low energy state due to its disorientating during packing and cooling, and meanwhile, the radius of gyration and mean square displacement results suggest that polymer chains don’t migrate but only elastically recover at the end shearing position. Moreover, the higher shear rate flow which molecular chains experience, the greater the degree of elastic recovery during packing and cooling process.
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