长支链聚乳酸在振荡剪切作用下的结晶行为

摘要

利用旋转流变仪在线研究了长支链聚乳酸(PLA)在振荡剪切作用下的结晶行为,并用差示扫描量热仪(DSC)测试了在不同条件下等温结晶的长支链PLA样品的最终结晶度.结果表明,振荡剪切作用对长支链PLA的结晶动力学有显著的促进作用;在实验设定的剪切速率和剪切时间范围内,长支链PLA的结晶速率随剪切速率的提高或剪切时间增加而加快,最终结晶度也随着剪切速率的提高或剪切时间增加而提高;但是,作为对比的线型PLA的结晶行为对振荡剪切作用不敏感.%The crystallization behavior of long-chain-branched polylactide (PLA) under oscillating shear effects was studied on-line by rotational rheometer.The final crytstallinity of long-chain-branched PLA samples isothermally crystallized under different conditions was tested by differential scanning calorimeter (DSC).The results show that the crystallization kinetics of long-chain-branched PLA could be dramatically improved by oscillating shear effects.In the preconditioned shear rate and shear time range,the crystallization rate of long-chain-branched PLA is increased by increasing the shear rate or shear time,and the final crystallinity is increased as well.However,the crystallization behavior of linear PLA which is used as comparison is insensitive to oscillating shear effects.