Chain conformation and dynamics in ultrahigh molecular weight polyethylene melts undergoing extensional–shear coupled flow: insight from dissipative particle dynamics simulation,Polymer International

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Chain conformation and dynamics in ultrahigh molecular weight polyethylene melts undergoing extensional–shear coupled flow: insight from dissipative particle dynamics simulation
Polymer International ( IF 2.9 ) Pub Date : 2020-06-17 , DOI: 10.1002/pi.6064
Junxia Wang ₁ , Xiaochuan Chen ₁ , Changlin Cao ₁ , Dingshan Yu ₁

Affiliation

A first attempt is made to present a detailed mesoscopic‐level description of the conformation and equilibrium dynamic properties of macromolecular chains in ultrahigh molecular weight polyethylene/polypropylene blends driven by extension‐dominated coupled flow, in comparison with shear‐dominated coupled flow. Extension‐dominated coupled flow can be defined as

\dot{γ}

= 0.005,

\dot{ε}

≥ 0.1 and shear‐dominated coupled flow as

\dot{ε}

= 0.1,

\dot{γ}

≥ 1, as verified by the time‐dependent evolution tendency of cell parameters and velocity profiles along the x, y, z directions. In the case of extension‐dominated coupled flow, the chains are greatly elongated and prefer to align along the flow direction, where the polypropylene chains appear to form a somewhat uniform layer. By comparison, the macromolecular chains assume a highly collapsed conformation and have a greater preference to align themselves perpendicular to the flow direction under shear‐dominated coupled flow, which can be ascribed to the rapid diffusion of polymer chains and a minor role of the weak van de Waals interaction in structural transitions. Analyses of conformational behavior derived from dissipative particle dynamics trajectories can, in general, serve as a useful guideline for experimental investigations of ultrahigh molecular weight polyethylene based materials prepared by eccentric rotor extrusion. © 2020 Society of Chemical Industry

中文翻译：

超高分子量聚乙烯熔体经历拉伸-剪切耦合流动的链构象和动力学：耗散颗粒动力学模拟的见解

进行首次尝试，是对由拉伸为主的耦合流驱动的超高分子量聚乙烯/聚丙烯共混物中大分子链的构象和平衡动力学性质的详细介观水平描述，与剪切为主的耦合流相比。扩展支配的耦合流可以定义为

\dot{γ}

= 0.005，

\dot{ε}

≥0.1并且以剪切力为主的耦合流为

\dot{ε}

= 0.1，

\dot{γ}

≥1，如通过沿x，y，z的细胞参数和速度分布的时间依赖性演化趋势所证明的指示。对于延伸支配的耦合流，链条会大大拉长，并倾向于沿流动方向排列，此时聚丙烯链条似乎会形成一定程度的均匀层。相比之下，大分子链具有高度折叠的构象，并且在剪切为主的耦合流下更倾向于垂直于流向对齐，这可以归因于聚合物链的快速扩散和弱货车的次要作用。结构转换中的de Waals相互作用。通常，从耗散粒子动力学轨迹得出的构象行为分析可作为通过偏心转子挤压法制备的超高分子量聚乙烯基材料的实验研究的有用指导。

更新日期：2020-06-17

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