聚合乳酸中的多态自我中毒:聚合物结晶中的新现象.
Shu-Gui Yang1,2, Xiang-Bing Zeng3, Feng Liu1,2
1Xi'an Jiaotong University, State Key Laboratory for Mechanical Behavior of Materials, Shaanxi International Research Center for Soft Matter, School of Material Science and Engineering, Xi'an 710049, China.
研究人员发现了聚乳酸结晶过程中的一种新的自我中毒机制,其中一种不太稳定的晶体形式 (α′) 阻碍了稳定的形式 (α) 的生长. 这一发现影响了聚合物加工和材料特性.
科学领域:
- 聚合物科学 聚合物科学
- 材料科学 材料科学 材料科学
- 结晶运动学 结晶运动学
背景情况:
- 自我中毒是聚合物结晶的一个已知的现象,通常观察到的增长率最小值.
- 以前的实例涉及不稳定的折叠或细分链,干扰稳定的晶体生长.
研究的目的:
- 识别和描述在聚乳酸 (PLA) 中的一种新型自我中毒机制.
- 为了研究这种自我中毒对PLA结晶动力学和材料特性的影响.
主要方法:
- 实验观察聚乳酸结晶动力学.
- 发展和应用一个增长率方程模型.
- 分析晶体形态动力学和叶片厚度变化.
主要成果:
- 在PLA中发现了一种新的自我中毒机制,其中不太稳定的α′晶体形式抑制了稳定的α形式的生长.
- 在生长率最低值以下,观察到片厚度的意外增加.
- 该模型揭示了α′形式的低折叠表面自由能量.
结论:
- 在PLA中自我中毒涉及到较不稳定的α′形式对稳定的α′晶体生长的动力阻碍.
- 这种现象,特别是在快速冷却过程中,导致低模量α′相的形成和无形含量增加.
- 由此产生的PLA的脆化归因于无形部分的物理衰老.
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