Understanding Constraint Release in Star/Linear Polymer Blends
Understanding Constraint Release in Star/Linear Polymer Blends
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DOI：
10.1021/ma402475a
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发表时间：
2014-03
期刊：
影响因子：
5.5
通讯作者：
M. Shivokhin;E. Ruymbeke;C. Bailly;D. Kouloumasis;N. Hadjichristidis;A. E. Likhtman
中科院分区：
文献类型：
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作者：
M. Shivokhin;E. Ruymbeke;C. Bailly;D. Kouloumasis;N. Hadjichristidis;A. E. Likhtman
在本文中，我们利用随机滑动弹簧模型来定量预测的应力松弛动力学的星星/线性共混物分离最长的松弛时间，我们分析的结果，以评估的有效性限制的两个主要模型描述相应的松弛机制的框架内的管图片（土井的管膨胀和Viovy的约束释放劳斯运动的管）。我们的主要目标是了解和模拟共混物中的星星组分的应力松弛函数。为此，我们将其弛豫函数分为三个区域，每个区域对应于不同的主要弛豫机制。在最初的快速Rouse运动之后，星星的松弛在中间时间由“瘦”管（由所有拓扑约束制成）主导，然后由“胖”管（仅由长寿障碍物制成）的探索主导。在更长的时间里，管膨胀图片为恒星的弛豫提供了正确的形状。然而，短线性链的影响导致以前从未描述过的时移因素。在分析星星链弛豫过程中摩擦系数的基础上，提出了一个预测这些时移因子的方程。这使我们能够开发一个分析方程结合所有的弛豫区，这是通过比较与模拟结果进行验证。
In this paper, we exploit the stochastic slip-spring model to quantitatively predict the stress relaxation dynamics of star/linear blends with well-separated longest relaxation times and we analyze the results to assess the validity limits of the two main models describing the corresponding relaxation mechanisms within the framework of the tube picture (Doi’s tube dilation and Viovy’s constraint release by Rouse motions of the tube). Our main objective is to understand and model the stress relaxation function of the star component in the blend. To this end, we divide its relaxation function into three zones, each of them corresponding to a different dominating relaxation mechanism. After the initial fast Rouse motions, relaxation of the star is dominated at intermediate times by the “skinny” tube (made by all topological constraints) followed by exploration of the “fat” tube (made by long-lived obstacles only). At longer times, the tube dilation picture provides the right shape for the relaxation of the stars. However, the effect of short linear chains results in time-shift factors that have never been described before. On the basis of the analysis of the different friction coefficients involved in the relaxation of the star chains, we propose an equation predicting these time-shift factors. This allows us to develop an analytical equation combining all relaxation zones, which is verified by comparison with simulation results.