Unusual Cold Crystallization Behavior in Physically Aged Poly(L-lactide)
Unusual Cold Crystallization Behavior in Physically Aged Poly(L-lactide)
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物理老化聚（L-丙交酯）中异常的冷结晶行为
DOI：
10.1021/jp2060816
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发表时间：
2011-09-22
影响因子：
3.3
通讯作者：
Yin, Qiang
中科院分区：
文献类型：
--
作者：
Na, Bing;Zou, Shufen;Yin, Qiang
已经进行了在玻璃过渡温度（t（g））下方且高于玻璃过渡温度（t（g））的聚（L-酰基）（PLLA）中冷结晶行为的比较研究。退火有益于局部秩序的产生和随后的冷结晶过程，在t（g）上方的PLLA中变得显着。出乎意料的是，形态学观察表明，与其相对较慢的结晶动力学相反，t（g）低于t（g）的PLLA中的高密度核。在物理老化的PLLA中，这种异常的结晶行为是由于降低的节段迁移率在t（g）上方的降低不完全恢复而引起的。相比之下，在T（g）上方的退火对晶体生长速率的影响很小，单独的成核密度增加了加速的结晶速率。
A comparative study of cold crystallization behavior in poly(L-lactide) (PLLA) annealed below and just above the glass transition temperature (T(g)) has been conducted. Annealing benefits the generation of local order and the subsequent cold crystallization process, which becomes significant in PLLA annealed just above T(g). Surprisingly, morphological observation reveals high density nuclei in PLLA annealed below T(g), contrary to its relatively slow crystallization kinetics. This unusual crystallization behavior in physically aged PLLA arises from the retarded crystal growth rate because of incomplete recovery of reduced segmental mobility above T(g). In contrast, annealing just above T(g) has little influence on the crystal growth rate, and the increased nucleation density alone accounts for the accelerated crystallization rate.