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在散装和纳米孔封闭的聚甲酸中,低障碍的物理衰老开始
Zijian Song1,2,3, Ming Wang3,4, Federico Caporaletti5
1School of Materials Science and Engineering, North University of China, Taiyuan 030051, China.
ACS macro letters
|February 3, 2026
概括
无形聚合物中的物理衰老涉及结构放松. 这项研究表明,聚甲基酸 (PMMA) 的早期衰老受局部模式的控制,而不仅仅是β-放松,挑战了当前的假设.
科学领域:
- 材料科学 材料科学 材料科学
- 聚合物物理 聚合物物理
- 物理化学 物理化学
背景情况:
- 无形聚合物中的物理衰老是玻璃过渡温度以下的缓慢结构放松过程.
- 异转换分析表明,在衰老过程中,激活障碍越来越大,接近α-放松.
- 最初的低障碍衰老模式的分子起源仍然不清楚.
研究的目的:
- 在无形聚合物中研究物理衰老早期阶段的分子起源.
- 为了分离和描述衰老运动的感应时间 (t_ind).
- 在老化过程中区分散装和封装聚甲酸 (PMMA) 的动态.
主要方法:
- 热量计用于测量衰老期间的热恢复.
- 宽带介电光谱被用来探测分子动力学.
- 对散装和纳米孔封闭聚甲酸 (PMMA) 进行了研究.
主要成果:
- 确定和描述了衰老动力学的诱导时间 (t_ind).
- t_ind对散装和封闭的PMMA都表现出明显的阿雷尼乌斯依赖.
- 与t_ind相关的激活能量与缓慢的Arrhenius过程保持一致,而不是β-放松.
结论:
- 这些发现挑战了这样的假设,即Arrhenius-like行为仅限于β-放松.
- 局部化分子模式似乎在无序固体中衰老的初始阶段发挥着重要作用.
- 在聚合物衰老动态中重新评估低障碍过程的分配是有必要的.
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