OBSERVATION OF THE COMPONENT DYNAMICS IN A MISCIBLE POLYMER BLEND BY DIELECTRIC AND MECHANICAL SPECTROSCOPIES
OBSERVATION OF THE COMPONENT DYNAMICS IN A MISCIBLE POLYMER BLEND BY DIELECTRIC AND MECHANICAL SPECTROSCOPIES
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DOI：
10.1021/ma00094a009
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发表时间：
1994-08-01
期刊：
影响因子：
5.5
通讯作者：
ROLAND, CM
中科院分区：
文献类型：
--
作者：
ALEGRIA, A;COLMENERO, J;ROLAND, CM
在等温条件下，在很宽的频率范围内，对聚乙烯乙烯 (PVE) 和聚异戊二烯 (PIP) 的混溶共混物中的局部链段弛豫进行了介电和机械弛豫测量。利用 PVE 对介电弛豫的贡献和 PIP 对机械弛豫的贡献的突出优势，我们能够解析某些共混物中每种组分的动力学。根据观察到的各个组件的动力学，我们将每个组件最可能的局部分段弛豫时间具有不同的大小以及不同的温度依赖性作为实验事实。此外，随着温度降低，各组分的弛豫谱变宽。因此，热流变简单性的崩溃不仅发生在每个组件的动力学中，更不用说当两个组件的贡献一起考虑时。这些效果表现出来的程度取决于共混物的组成。所有这些实验特征都表明符合共混物的分段动力学理论，该理论是通过考虑局部浓度波动而作为均聚物耦合模型的推广而获得的。
Dielectric and mechanical relaxation measurements of the local segmental relaxation in miscible blends of poly(vinylethylene) (PVE) and polyisoprene (PIP) have been made under isothermal conditions over a wide range of frequency. Taking advantage of the prominence of respectively the PVE contribution to dielectric relaxation and the PIP contribution to mechanical relaxation, we are able to resolve the dynamics of each component in some of the blends. From the observed dynamics of individual components, we establish as experimental facts that the most probable local segmental relaxation time of each component has a different magnitude as well as different temperature dependence. Moreover, the relaxation spectrum of each component broadens as temperature is decreased. Thus a breakdown of thermorheological simplicity occurs not only in the dynamics of each component but a fortiori when the contributions from both components are considered together. The degree to which these effects manifest themselves depends on the blend composition. All these experimental features are shown to be in accord with a theory of segmental dynamics for blends that is obtained as a generalization of the coupling model for homopolymers by taking into account local concentration fluctuations.