Unraveling Dynamics of Entangled Polymers in Strong Extensional Flows,Macromolecules

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Unraveling Dynamics of Entangled Polymers in Strong Extensional Flows
Macromolecules ( IF 5.1 ) Pub Date : 2019-01-31 00:00:00 , DOI: 10.1021/acs.macromol.8b02308
Soroush Moghadam , Indranil Saha Dalal ₁ , Ronald G. Larson

Affiliation

The traditional Doi–Edwards tube model, applied to extensional flows at strain rates above the inverse Rouse time, predicts that the tube deforms affinely, which implies that the extensional stress reaches its plateau as soon as the chain has become locally fully stretched, even if the chain is still folded, and far from being completely unraveled. By starting from a state in which the chain is in a locally fully stretched, but folded, state, we develop an “entangled kink dynamics algorithm” that predicts the final unraveling of an ensemble of mutually entangled, folded chains, driven by a combination of drag forces and chain tension, with negligible Brownian motion. Equations for motions of both entangled folds and unentangled folds in which two chains hook together at a single fold point are derived and solved, including the effects of constraint release that occurs when the end of one chain passes through the fold at which that chain is entangled. This model predicts that the stress approaches its final plateau stress only after complete chain unraveling, which for long chains is at much higher strains than in the tube model.

中文翻译：

强拉伸流中纠缠聚合物的解体动力学

传统的Doi–Edwards管模型应用于在反向Rouse时间以上的应变速率下的拉伸流动，预测该管仿射变形，这意味着一旦链条局部完全拉伸，即使链子仍然折叠着，并没有被完全拆开。从链处于局部完全拉伸但处于折叠状态的状态开始，我们开发了一种“纠缠扭结动力学算法”，该算法可预测相互缠结，折叠链的整体最终解散，这些纠缠是由以下因素共同驱动的：阻力和链条张力，布朗运动可忽略不计。推导并求解了纠缠褶皱和非纠缠褶皱的运动方程，其中两个链在单个折叠点处钩在一起，包括约束释放的效果，这种约束释放是在一条链的末端穿过该链缠结的折叠时发生的。该模型预测应力仅在链完全解开后才达到其最终的平台应力，对于长链而言，该应力要比管模型高得多。

更新日期：2019-01-31

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