Some examples of possible descriptions of dynamic properties of polymers by means of the coupling model
Some examples of possible descriptions of dynamic properties of polymers by means of the coupling model
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DOI：
10.1007/bf00366672
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发表时间：
1997-05
期刊：
影响因子：
2.3
通讯作者：
K. Ngai;D. Plazek;R. Rendell
中科院分区：
文献类型：
--
作者：
K. Ngai;D. Plazek;R. Rendell
感谢John D.教授的研究努力。Ferry等人在过去的几十年中，聚合物的粘弹特性已经被广泛地确定。从这一智慧的积累，聚合物粘弹性已成为一个成熟的研究领域。聚合物粘弹性的这一基本知识使我们有可能辨别出与我们之一（DJP）发现的明显建立的一般规则的偏差，继续由Ferry教授开始的详尽实验测量的传统。从不同实验室对聚合物进行的许多实验研究中，也可以清楚地看到，这些粘弹性异常是普遍的，而不是例外的特征。因此，他们提出了一个真正令人满意的理解聚合物粘弹性的追求显着的问题。耦合模型（CM）已被用来合理化一些偏离热流变简单。在聚合物的粘弹性行为的领域中，我们首先考虑的本地节段运动是负责的玻璃温度和显示，CM提供了一个一致的描述中的模量或顺应性表示。接下来，我们阐明了几个粘弹性异常，起源于不同的粘弹性机制是热流变复杂的。最后，我们重新使用CM的纠缠聚合物链的终端松弛的原始配方。在原始公式中，忽略了其他链对一条链施加的约束的横向性质，导致无法解释末端松弛的形状，尽管它在其他方面是成功的。一个新的配方，其中包括横向性质的约束和随后的缓解时，终端松弛达到，恢复了一致性的预测与终端松弛的单分散聚异戊二烯熔体介电探测。所得结果也能描述聚异戊二烯稀探针在聚丁二烯基体和网络中的实验数据。
Thanks to the research efforts of Prof. John D. Ferry and others over the last several decades, the viscoelastic properties of polymers have been extensively determined. From this accumulated wisdom, polymer viscoelasticity has become a mature field of research. This basic knowledge of polymer viscoelasticity has made it possible to discern the deviations from the apparently established general rules that one of us (DJP) have found, continuing the tradition of exhaustive experimental measurement started by Prof. Ferry. From many experimental studies on polymers carried out in different laboratories, it has also become clear that these viscoelastic anomalies are general and not exceptional features. Therefore, they pose significant problems in the quest of a truly satisfactory understanding of polymer viscoelasticity. The Coupling Model (CM) has been used to rationalize a number of deviations from thermorheological simplicity. In the realm of polymer viscoelastic behavior, we consider first the local segmental motion that is responsible for the glass temperature and show that the CM provides a consistent description in either the modulus or the compliance representation. Next, we elucidate several viscoelastic anomalies which originate from the different viscoelastic mechanisms being thermorheologically complex. Finally, we revisit the original formulation of the terminal relaxation of entangled polymer chains using the CM. The neglect of the lateral nature of the constraints imposed on one chain by other chains in the original formulation leads to failure in explaining the shape of the terminal relaxation, although it is successful in other aspects. A new formulation, which includes the lateral nature of the constraints and its subsequent mitigation when the terminal relaxation is reached, has restored consistency of the prediction with the terminal relaxation of a monodisperse polyisoprene melt probed dielectrically. The results can describe also the experimental data of dilute polyisoprene probes in polybutadiene matrices and in networks.