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首页> 外文期刊>Macromolecules >Molecular Dynamics Simulations of Short-Chain Branched Bimodal Polyethylene: Topological Characteristics and Mechanical Behavior
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Molecular Dynamics Simulations of Short-Chain Branched Bimodal Polyethylene: Topological Characteristics and Mechanical Behavior

机译：短链分枝双峰聚乙烯的分子动力学模拟：拓扑特性和力学行为

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It has previously been shown that polyethylene (PE) with a bimodal molar mass distribution has a high fracture toughness. Our approach has been to use coarse-grained (CG) molecular dynamics (MD) simulations to investigate the effects of including short-chain branches in the high molar mass fraction of bimodal PE on topological features and mechanical behavior of the material. The CG potentials were derived, validated, and utilized to simulate melt equilibration, cooling, crystallization, and mechanical deformation. Crystallinity, tie chain, and entanglement concentrations were continuously monitored. During crystallization, the branched bimodal systems disentangled to a lesser degree and ended up with a higher entanglement density than the linear bimodal systems simulated in our previous study. The increase in entanglement concentration was proportional to the content of the branched high molar mass fraction. A significantly higher tie chain concentration was obtained in the short-chain branched bimodal systems than in the linear systems. The increase in the number of ties was more pronounced than the increase in the number of entanglements. The tie chain concentration was not proportional to the content of the high molar mass fraction. Despite a lower crystal thickness and content, the elastic modulus and yield stress values were higher in the branched bimodal systems. A more pronounced strain hardening region was observed in the branched systems. It was suggested that the higher tie chain and entanglement concentration prior to the deformation, the more extensive disentanglement during the deformation, and the disappearance of formed voids prior to failure point were the reasons for the observed higher toughness of the short-chain branched bimodal PE compared with that of the linear bimodal systems. The toughest system, which contained respectively 25 and 75 wt % low molar mass and branched high molar mass fractions, had the highest tie chain concentration and the
机译：先前已经表明，具有双峰摩尔质量分布的聚乙烯（PE）具有高裂缝韧性。我们的方法一直使用粗粒（CG）分子动力学（MD）模拟，以研究在拓扑特征和材料的高摩尔质量分数中包括短链分支的影响。衍生，验证和利用CG电位来模拟熔融平衡，冷却，结晶和机械变形。连续监测结晶性，系链和缠结浓度。在结晶期间，支化双峰系统脱离较小程度，并以比我们之前的研究中模拟的线性双峰系统更高的缠结密度最终。缠结浓度的增加与支化高摩尔质量级分的含量成比例。在短链支化双峰系统中获得显着更高的延长链浓度，而不是线性系统。关系数量的增加比纠缠数量的增加更加明显。系带链浓度与高摩尔质量级分的含量没有成比例。尽管晶体厚度和含量较低，但支化双峰系统的弹性模量和产率应力值较高。在支化系统中观察到更明显的应变硬化区域。建议在变形之前的较高的扎带和缠结浓度，变形期间更广泛的脱垂，并且在发生故障点之前形成的空隙消失是观察到短链支化双峰PE的更高韧性的原因与线性双峰系统相比。最强的系统，分别含有25和75wt％的低摩尔质量和支链高摩尔质量分数，具有最高的扎带链浓度和

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  • 来源
    《Macromolecules》 |2019年第3期|共12页
  • 作者

    Moyassari Ali; Gkourmpis Thomas; Hedenqvist Mikael S.; Gedde Ulf W.;

  • 作者单位

    KTH Royal Inst Technol Sch Engn Sci Chem Biotechnol &

    Hlth Fibre &

    Polymer Technol SE-10044 Stockholm Sweden;

    Borealis AB Innovat &

    Technol SE-44486 Stenungsund Sweden;

    KTH Royal Inst Technol Sch Engn Sci Chem Biotechnol &

    Hlth Fibre &

    Polymer Technol SE-10044 Stockholm Sweden;

    KTH Royal Inst Technol Sch Engn Sci Chem Biotechnol &

    Hlth Fibre &

    Polymer Technol SE-10044 Stockholm Sweden;

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  • 正文语种 eng
  • 中图分类 高分子化学（高聚物）;
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