Study on liquid-liquid transition of chlorinated butyl rubber by positron annihilation lifetime spectroscopy
Study on liquid-liquid transition of chlorinated butyl rubber by positron annihilation lifetime spectroscopy
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DOI：
10.1063/1.2335376
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发表时间：
2006-09
影响因子：
4
通讯作者：
Jinrong Wu;Guangsu Huang;Qiying Pan;Liangliang Qu;Yuchan Zhu;Bo Wang
中科院分区：
文献类型：
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作者：
Jinrong Wu;Guangsu Huang;Qiying Pan;Liangliang Qu;Yuchan Zhu;Bo Wang
在非晶态聚合物中，在玻璃化转变温度（Tg）以上是否存在液-液转变（Tll）仍然是一个有争议的话题。本文用正电子湮没寿命谱法研究了氯化丁基橡胶硫化和未硫化样品中铊的含量。结果发现，两种样品的正电子偶素寿命和自由体积分数的温度谱都清楚地显示出在−70和−10°C附近的两个拐点，分别对应于Tg和Tll，而正电子偶素强度在过渡区降低，这可能意味着分子协同效应。此外，应采用两个方程来描述自由体积分数的发展后，Tg。
The existence of liquid-liquid transition (Tll) above the glass transition (Tg) in amorphous polymers remains a controversial topic. In this letter, positron annihilation lifetime spectroscopy was used to detect Tll in cured and uncured chlorinated butyl rubber. It is found that the temperature spectra of orthopositronium lifetime and free-volume fraction of both samples clearly demonstrate two inflection points around −70 and −10°C, corresponding to Tg and Tll, respectively, while the orthopositronium intensity decreases at the transition regions, which may imply molecular cooperativity. Moreover, two equations should be adopted to describe the development of free-volume fraction after Tg.