Functionalization of poly (butylene adipate-co-terephthalate) and its toughening effect on poly (lactic acid)

In the study, poly (butylene adipate-co-terephthalate) (PBAT) was grafted with glycidyl methacrylate (GMA) in the presence of the co-monomer N-vinyl pyrrolidone (NVP), and then it was employed to enhance the toughness of poly (lactic acid) (PLA). It was found the functionalized PBAT had a better toughening effect on PLA than neat PBAT. The PLA/PBAT-GMA (70/30) blend undergoes brittle-ductile transition when the graft monomer ratio of GMA:NVP:DCP exceeds 2:2:0.2. The impact strength of PLA/PBAT-GMA (3:3:0.3) blend reached 65.7 kJ/m2, with an elongation at break of 210.9 %. Additionally, rheological tests showed that the entanglement ability of chain segments was enhanced, it was ascribed to the improvement of the compatibility between PLA and PBAT-GMA owing to the compatibilization reaction between the epoxy functional groups in PBAT-GMA and the carboxyl groups in PLA, resulting in the formation of a new copolymer. DMA tests revealed that the Tg of PLA and PBAT-GMA were close to each other, confirming the improved compatibility of the PLA/PBAT-GMA blends. This offers a novel method for preparing super-though PLA.