An investigation on the molecular mobility through the glass transition of chlorinated butyl rubber |
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Authors: | Jinrong Wu Guangsu Huang Qiying Pan Jing Zheng Yuchan Zhu Bo Wang |
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Affiliation: | aCollege of Polymer Science and Engineering, State Key Laboratory of Polymer Material Engineering, Sichuan University, Chengdu 610065, China;bDepartment of physics, Wuhan University, Wuhan 430072, China |
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Abstract: | 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 ″ 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. |
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Keywords: | Chlorinated butyl rubber α Process Slow process |
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