An investigation on the molecular mobility through the glass transition of chlorinated butyl rubber
An investigation on the molecular mobility through the glass transition of chlorinated butyl rubber
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DOI：
10.1016/j.polymer.2007.11.006
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发表时间：
2007-12
期刊：
影响因子：
4.6
通讯作者：
Jinrong Wu;Guangsu Huang;Qiying Pan;Jing Zheng;Yuchan Zhu;Bo Wang
中科院分区：
文献类型：
--
作者：
Jinrong Wu;Guangsu Huang;Qiying Pan;Jing Zheng;Yuchan Zhu;Bo Wang
本文利用动态力学分析（DMA）、介电谱（DS）和正电子湮没寿命谱（PALS）来研究氯化丁基橡胶（CIIR），以揭示其独特的弛豫行为。 CIIR的动态机械损耗角正切显示出不对称的宽结构，在高温侧有最大峰，在低温侧有肩峰。 DS 阐明，与 ɛ″ 峰完全对应的肩峰是源于局部节段运动的 α 过程。而最大峰值则分配给较长链段运动引起的缓慢过程。慢速过程比α过程表现出更强的频率依赖性。 PALS 分析还显示了这两个过程；此外，它表明 CIIR 表现出非常有效的链堆积。由于有效的链堆积，较长链段的运动被延迟并在时间尺度上与局部链段运动分离。除了分子间协同性低之外，这种效应是 CIIR 具有双峰结构的另一个原因。
In this paper, dynamic mechanical analysis (DMA), dielectric spectroscopy (DS) and positron annihilation lifetime spectroscopy (PALS) were used to study chlorinated butyl rubber (CIIR), in order to shed light on its unique relaxation behaviors. The dynamic mechanical loss tangent of CIIR reveals an asymmetrical broad structure with a maximum peak on the high-temperature side and a shoulder peak on the low-temperature side. DS clarifies that the shoulder peak, which exactly corresponds to the ɛ″ peak, is the α process originating from the local segmental motion. While the maximum peak is assigned to the slow process arising from the motion of longer chain segments. The slow process exhibits stronger frequency dependence than the α process. The PALS analysis also shows the two processes; moreover, it suggests that CIIR exhibits very effective chain packing. It is due to the effective chain packing that the motion of longer chain segments is retarded and separates from the local segmental motion in time scale. This effect is another reason for the two-peak structure of CIIR, besides the low intermolecular co-operativity.