The strain dependence of the Johari–Goldstein (JG)-β relaxation time, as well as the directional dependence, was systematically investigated for stretched cross-linked polybutadiene using time-domain interferometry. We found that the strain dependence of the JG-β relaxation time is directionally dependent, contrary to expectation: the relaxation time of the JG-β motion, whose displacement is perpendicular to the stretching direction, decreases with stretching, whereas the relaxation time of the parallel JG-β motion changes little. This result is distinct from the previously reported strain dependence of the α relaxation time, where the relaxation time increases isotropically with stretching. Thus, the difference in the strain dependence of the relaxation time between the α and JG-β processes suggests a microscopic origin and requires the modification of the conventional dynamic picture for stretched polymers.

中文翻译：

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时域干涉法显微观察交联聚丁二烯拉伸过程中 Johari-Goldstein-β 过程的各向异性


使用时域干涉仪系统地研究了拉伸交联聚丁二烯的 Johari-Goldstein (JG)-β 弛豫时间的应变依赖性以及方向依赖性。我们发现JG-β弛豫时间的应变依赖性是方向相关的，与预期相反：位移垂直于拉伸方向的JG-β运动的弛豫时间随着拉伸而减小，而JG-β运动的弛豫时间随着拉伸而减小。平行JG-β运动变化不大。该结果与先前报道的α弛豫时间的应变依赖性不同，其中弛豫时间随着拉伸各向同性地增加。因此，α 和 JG-β 过程之间弛豫时间的应变依赖性差异表明了微观起源，并且需要修改拉伸聚合物的传统动态图。