Unusual Cold Crystallization Behavior in Physically Aged Poly(l-lactide)

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• 作者：Bing Na ; Shufen Zou ; Ruihua Lv ; Mingbiao Luo ; Huayan Pan ; Qiang Yin
• 刊名：Journal of Physical Chemistry B
• 出版年：2011
• 出版时间：September 22, 2011
• 年：2011
• 卷：115
• 期：37
• 页码：10844-10848
• 全文大小：809K
• 年卷期：v.115,no.37(September 22, 2011)
• ISSN：1520-5207

文摘

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.