The Role of the Rigid Amorphous Fraction on Cold Crystallization of Poly(3-hydroxybutyrate)
The Role of the Rigid Amorphous Fraction on Cold Crystallization of Poly(3-hydroxybutyrate)
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DOI：
10.1021/ma3010907
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发表时间：
2012-07-24
期刊：
影响因子：
5.5
通讯作者：
Righetti, Maria Cristina
中科院分区：
文献类型：
--
作者：
Di Lorenzo, Maria Laura;Gazzano, Massimo;Righetti, Maria Cristina
在这方面的贡献详细的流动性的无定形链的聚（3-羟基丁酸酯）（PHB）的结晶的影响。热分析表明，最初无定形的聚羟基丁酸酯的发生两个不同的结晶，表明通过两个阶段的过程进行冷结晶。考虑到玻璃化/失透的刚性无定形部分（RAF）的结晶动力学的PHB的作用的实验数据进行了合理化。在冷结晶的第一阶段期间与晶体生长同时建立的刚性非晶结构在完成之前减慢结晶。结晶和无定形链段之间的耦合通过产生围绕晶体的固定无定形层来阻碍进一步结晶。温度的进一步升高导致RAF的动员。一旦与晶体耦合的非晶层获得足够的迁移率，就可以发生将PHB片段容纳成有序结构所需的链重排，并且可以进一步进行结晶。这项研究表明，刚性无定形部分的物理状态影响聚（3-羟基丁酸酯）的结晶动力学。
The influence of mobility of the amorphous chains on crystallization of poly(3-hydroxybutyrate) (PHB) is detailed in this contribution. Thermal analysis of initially amorphous PHB reveals the occurrence of two distinct exotherms, indicating that cold crystallization proceeds via a two-stage process. The experimental data were rationalized taking into account the role of vitrification/devitrification of the rigid amorphous fraction (RAF) on crystallization kinetics of PHB. The rigid amorphous structure, which is established simultaneously with crystals growth during the first stage of cold crystallization, slows down crystallization before completion. The coupling between the crystalline and amorphous segments hinders further crystallization by the creation of an immobilized amorphous layer that surrounds the crystals. Further increase of the temperature results in mobilization of the RAF. Once the amorphous layer coupled with the crystals has gained sufficient mobility, chain rearrangements needed to accommodate the PHB segments into ordered structures can take place, and crystallization can proceed further. This study demonstrates that the physical state of the rigid amorphous fraction affects the crystallization kinetics of poly(3-hydroxybutyrate).