Simulating Startup Shear of Entangled Polymer Melts.
Simulating Startup Shear of Entangled Polymer Melts.
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DOI：
10.1021/acsmacrolett.5b00708
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发表时间：
2015-11
影响因子：
5.8
通讯作者：
Jingle Cao;A. E. Likhtman
中科院分区：
文献类型：
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作者：
Jingle Cao;A. E. Likhtman
启动剪切流变学是用于表征聚合物流动和测试聚合物动力学的各种模型的标准实验。一个丰富的现象学的纠缠单分散线性聚合物在这样的测试中的行为，记录剪切应力超调作为剪切速率和分子量的函数。管理论在描述这些现象时做了合理的定性工作，尽管它涉及几个极端的近似，并且一致性可能是偶然的。最近，Lu和同事发表了几篇论文[例如，吕ACS宏Lett. 2014，3，569-573]报道了来自线性缠结聚合物的分子动力学模拟的结果，其与理论和实验相矛盾。在这些观察的基础上，他们对管理论做出了非常严肃的结论，这似乎还为时过早。在这封信中，我们重复了Lu等人的模拟，并系统地表明，无论是他们的模拟结果还是与理论的比较都没有得到证实。
Start-up shear rheology is a standard experiment used for characterizing polymer flow, and to test various models of polymer dynamics. A rich phenomenology is developed for behavior of entangled monodisperse linear polymers in such tests, documenting shear stress overshoots as a function of shear rates and molecular weights. A tube theory does a reasonable qualitative job at describing these phenomena, although it involves several drastic approximations and the agreement can be fortuitous. Recently, Lu and co-workers published several papers [e.g., Lu ACS Macro Lett. 2014, 3, 569-573] reporting results from molecular dynamics simulations of linear entangled polymers, which contradict both theory and experiment. On the basis of these observations, they made very serious conclusions about the tube theory, which seem to be premature. In this letter, we repeat simulations of Lu et al. and systematically show that neither their simulation results nor their comparison with theory is confirmed.