Crystallization, thermal and mechanical behavior of oligosebacate plasticized poly(lactic acid) films

Abstract The biodegradable aliphatic oligoester oligo(trimethylene separate) (OTS) was synthesized by polycondensation and used to plasticize poly(lactic acid) (PLA). Casting films of PLA and PLA/OTS with concentrations of 1, 5 and 10 wt.% were prepared, and these films were characterized by thermal analyses, crystallinity, rheology and mechanical tests. DSC revealed the decrease in the Tg of PLA films with addition of the oligomer and a partial immiscibility. Addition of OTS to PLA slightly decrease the thermal stability as well as increase the degree of crystallinity of these films. Dynamic-mechanical analyses of casting films showed that the PLA/OTS system presented lower storage modulus than PLA and mechanical test revealed an increased in the elongation at break for PLA films containing the oligoester. The results make possible to conclude that the oligomer synthesized from bio-based monomers acts as a plasticizer of PLA increasing the PLA ductility.

摘要 本研究通过缩聚反应合成了可生物降解脂肪族低聚酯——低聚（三亚甲基分隔酯）（OTS），并将其用作聚乳酸（PLA）的增塑剂。制备了纯PLA薄膜以及添加1、5、10 wt.% OTS的PLA/OTS复合流延薄膜，通过热分析、结晶度表征、流变学测试与力学性能测试对所有样品进行了系统性表征。差示扫描量热法（DSC）结果显示，随着低聚物的添加，PLA薄膜的玻璃化转变温度（Tg）出现下降，且二者呈现部分不相容性。向PLA基体中添加OTS会略微降低体系的热稳定性，同时提升复合薄膜的结晶度。对所制流延薄膜的动态力学分析表明，PLA/OTS复合体系的储能模量低于纯PLA薄膜；力学性能测试则显示，添加该低聚酯的PLA薄膜的断裂伸长率有所提升。综合上述实验结果可知，以生物基单体制备得到的低聚物可作为PLA的高效增塑剂，有效改善聚乳酸的延展性。