Molecular Dynamics Simulations on the Demolding Process for Nanostructures with Different Aspect Ratios in Injection Molding
Molecular Dynamics Simulations on the Demolding Process for Nanostructures with Different Aspect Ratios in Injection Molding
复制标题
不同长径比纳米结构注塑脱模过程的分子动力学模拟
DOI：
10.3390/mi10100636
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发表时间：
2019-10-01
期刊：
影响因子：
3.4
通讯作者：
Zhou, Mingyong
中科院分区：
文献类型：
--
作者：
Weng, Can;Yang, Dongjiao;Zhou, Mingyong
注塑成型是大批量生产聚合物制品的最有潜力的技术之一。填充过程以及脱模过程影响注射成型纳米结构的质量。在这项研究中，具有不同的深宽比（D/W）的纳米腔的构建和脱模过程的分子动力学模拟进行。分析了构象变化和密度分布。采用界面粘附法研究了镍模镶块与聚丙烯（PP）的相互作用机理。结果表明，纳米结构的分离首先发生在纳米结构的肩部。纳米结构和整个PP层都被拉伸，导致脱模后平均密度急剧下降。在分离过程中，在3：1纳米结构中可以观察到回转半径的最大增加和最低速度。纳米结构发生变形，但整个结构仍然处于良好的形状。随着D/W的增大，粘附能增大。脱模力迅速增加到峰值点，然后逐渐减小到零。由于界面相互作用，大部分力来自纳米结构上的粘附和摩擦。
Injection molding is one of the most potential techniques for fabricating polymeric products in large numbers. The filling process, but also the demolding process, influence the quality of injection-molded nanostructures. In this study, nano-cavities with different depth-to-width ratios (D/W) were built and molecular dynamics simulations on the demolding process were conducted. Conformation change and density distribution were analyzed. Interfacial adhesion was utilized to investigate the interaction mechanism between polypropylene (PP) and nickel mold insert. The results show that the separation would first happen at the shoulder of the nanostructures. Nanostructures and the whole PP layer are both stretched, resulting in a sharp decrease in average density after demolding. The largest increase in the radius of gyration and lowest velocity can be observed in 3:1 nanostructure during the separation. Deformation on nanostructure occurs, but nevertheless the whole structure is still in good shape. The adhesion energy gets higher with the increase of D/W. The demolding force increases quickly to the peak point and then gradually decreases to zero. The majority of the force comes from the adhesion and friction on the nanostructure due to the interfacial interaction.