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Effect of Macromolecular Chain Movement and the Interchain Interaction on Crystalline Nucleation and Spherulite Growth of Polylactic Acid under High-Pressure CO2
Macromolecules ( IF 5.1 ) Pub Date : 2019-12-18 , DOI: 10.1021/acs.macromol.9b01601
Shaojie Li 1 , Taoyi Chen 2 , Xia Liao 1, 3 , Weiqiang Han 1 , Zhihui Yan 1 , Junsong Li 1 , Guangxian Li 1
Affiliation  

Crystallization behavior of polylactic acid (PLA) under CO2 is meaningful due to its effect on foaming behavior during CO2 foaming, while present studies mainly concentrated on overall crystallization behavior. In this study, the effect of CO2 on nucleation and spherulite growth of PLA crystals was in situ investigated separately. During saturation, sorption of CO2 in PLA diluted the molecular chain density, thus increasing molecular chain mobility and weakening the interchain interaction, which reduced the amount of crystal nuclei in PLA. On the other hand, the spherulite growth rate reduced at high temperature and increased at low temperature attributed to the enhanced chain mobility under CO2. Thus, overall crystallization was controlled by the spherulite growth rate at low temperature and crystalline nucleation at high temperature under CO2. Besides, CO2 restricted lamella branching, resulting in an increased lamella thickness and z axis size. Current results revealed the effect of tunable molecular chain mobility and the interchain interaction adjusted by CO2 on nucleation and spherulite growth of PLA.

中文翻译:

高压CO 2下大分子链运动和链间相互作用对聚乳酸结晶成核和球晶生长的影响

聚乳酸(PLA)在CO 2下的结晶行为是有意义的,因为它对CO 2发泡过程中的发泡行为有影响,而目前的研究主要集中在总体结晶行为上。在这项研究中,分别研究了CO 2对PLA晶体成核和球晶生长的影响。在饱和过程中,PLA中CO 2的吸附稀释了分子链密度,从而增加了分子链的迁移性并削弱了链间相互作用,从而减少了PLA中的晶核数量。另一方面,由于在CO 2下链迁移率提高,球晶的生长速率在高温下降低而在低温下增长。。因此,通过CO 2下低温下的球晶生长速率和高温下的晶体成核作用来控制总体结晶。此外,CO 2限制了薄片的分支,导致薄片的厚度和z轴尺寸的增加。目前的结果表明,可调节的分子链迁移率和CO 2调节的链间相互作用对PLA的成核和球晶生长的影响。
更新日期:2019-12-19
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