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：可生物降解脂肪族低聚酯低聚(三亚甲基分离物)（oligo(trimethylene separate)，OTS）通过缩聚反应合成，并被用于增塑聚乳酸（poly(lactic acid)，PLA）。制备了纯PLA薄膜以及OTS质量分数分别为1%、5%和10%的PLA/OTS共混浇铸薄膜，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薄膜进行了表征。差示扫描量热法（DSC）结果显示，随着该低聚物的添加，PLA薄膜的玻璃化转变温度（Tg）降低，且二者存在部分不相容性。向PLA中添加OTS会略微降低薄膜的热稳定性，同时提升其结晶度。对浇铸薄膜的动态力学分析表明，PLA/OTS共混体系的储能模量低于纯PLA薄膜；力学性能测试结果显示，添加该低聚酯的PLA薄膜的断裂伸长率有所提升。上述实验结果可证实，由生物基单体制备的低聚物可作为PLA的增塑剂，有效提升聚乳酸的延展性。