Direct Comparison of Probe Reorientation and Linear Mechanical Measurements of Segmental Dynamics in Glassy Poly(methyl methacrylate)
Direct Comparison of Probe Reorientation and Linear Mechanical Measurements of Segmental Dynamics in Glassy Poly(methyl methacrylate)
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DOI：
10.1021/acs.macromol.8b01522
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发表时间：
2018-09
期刊：
影响因子：
5.5
通讯作者：
J. Ricci;Trevor Bennin;M. Ediger
中科院分区：
文献类型：
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作者：
J. Ricci;Trevor Bennin;M. Ediger
在聚合物玻璃上进行了光学探针重定向实验和线性响应机制下的机械应力松弛测量。轻度交联的聚（甲基丙烯酸甲酯）（PMMA）的分段动力学监测通过这两种方法在9和24 K之间的温度低于玻璃化转变温度（Tg）和超过8小时的老化过程中。这两种方法的弛豫时间范围为1.7 × 10 ~（-1）。从两个实验中获得了相似的结果，除了老化速率略有差异。观察到光学和机械获得的弛豫时间之间的差异为0.3十年（0.2倍），主要与探针的大小有关。两个实验都给出了Kohlrausch-Williams-Watts（KWW）β参数的接近0.3的值。这些结果提供了一个重要的基线的解释光学探针在非线性变形过程中的重定向实验。
Optical probe reorientation experiments and mechanical stress relaxation measurements in the linear response regime were performed on a polymer glass. Segmental dynamics of lightly cross-linked poly(methyl methacrylate) (PMMA) were monitored via both methods at temperatures between 9 and 24 K below the glass transition temperature (Tg) and over the course of 8 h of aging. Relaxation times from the two methods cover a range of ∼1.7 decades. Similar results were obtained from the two experiments other than a slight difference in the aging rate. A difference of ∼0.3 decades (a factor of ∼2) is observed between the optically and mechanically obtained relaxation times, related primarily to the size of the probe. Both experiments give a value near 0.3 for the Kohlrausch–Williams–Watts (KWW) β parameter. These results provide an important baseline for the interpretation of optical probe reorientation experiments during nonlinear deformation.