Stretch-orientation-induced reduction of friction in well-entangled bidisperse blends: a dual slip-link simulation study
Stretch-orientation-induced reduction of friction in well-entangled bidisperse blends: a dual slip-link simulation study
复制标题
良好缠结的双分散共混物中拉伸取向引起的摩擦减少：双滑移连接模拟研究
DOI：
10.1007/s00397-022-01378-5
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发表时间：
2022
期刊：
影响因子：
2.3
通讯作者：
Taniguchi Takashi
中科院分区：
文献类型：
--
作者：
Miyamoto Souta;Sato Takeshi;Taniguchi Takashi
采用滑动连接法研究了具有减摩机制的双分散缠结聚合物共混物在高变形速率下的流变性能。拉伸和取向（SORF）引起的摩擦降低机制对于预测单轴拉伸流动下的粘弹性是重要的。为了测试该机制对于双分散体系的适用性，我们将摩擦减少的表达式（Yaoita等人，Macromolecules 45：2773-2782）并入Doi-Takimoto滑动连接模型（DT模型）（Doi和TakimotoPhilos Trans R Soc Lond A361：641-652）。对于六个实验双分散系统，即，四个聚苯乙烯共混物和两个聚异戊二烯共混物，扩展的DT模型，其中的顺序参数的摩擦减少机制是通过组件的平均值评估成功地再现单轴拉伸和剪切下的数据。这一成功是由于使用每个组分的统计平均值抑制了较长链的拉伸。通过这项研究，SORF表达式提高了流变学预测的双分散缠结聚合物熔体单轴拉伸流动下的应变速率相当于或大于逆的Rouse松弛时间的长链。此外，使用拉伸的组分平均值的SORF预测再现了稳定粘度，因为在拉伸流动下，具有不同分子量的组分的状态根据其劳斯松弛时间而明显彼此不同。这一发现意味着，对于链动力学，摩擦系数由周围聚合物链的状态和链的状态决定。
We investigated the rheological properties of bidisperse entangled-polymer blends under high-deformation-rate flows by slip-link simulations with a friction reduction mechanism. The friction reduction mechanism induced by the stretch and orientation (SORF) is important to predict the viscoelasticity under uniaxial elongational flows. To test the applicability of this mechanism for bidisperse systems, we incorporated an expression of friction reduction (Yaoita et al.Macromolecules45:2773–2782 ) into the Doi-Takimoto slip-link model (DT model) (Doi and TakimotoPhilos Trans R Soc Lond A361:641–652 ). For six experimental bidisperse systems, i.e., four polystyrene blends and two polyisoprene blends, the extended DT model where the order parameter of the friction reduction mechanism is evaluated through the component averages succeeds in reproducing the data under uniaxial elongation and shear. This success is due to the suppression of the stretch of the longer chains using the statistical average over each component. Through this study, the SORF expression improves the rheological prediction for bidisperse entangled polymer melts under uniaxial elongational flows with strain rates comparable to or larger than the inverse of the Rouse relaxation time of the longer chains. Additionally, the predictions with the SORF using the component average for the stretches reproduce the steady viscosities because under elongational flows, the states of the components with different molecular weights clearly differ from each other depending on their Rouse relaxation time. The finding means that for chain dynamics, the friction coefficient is determined by the state of the surrounding polymer chains and the state of the chain.