Polylactic acid/poly(butylene diglycolate-co-butylene terephthalate) blends with improved toughness

Polylactic acid (PLA), which is widely used in degradable packaging and medicine, has attracted much attention in recent years. However, PLA's ductility and processability still need to be improved. Previous literature indicated that poly(butylene diglycolate-co-butylene terephthalate) (PBDT) had good ductility, and degradability due to the introduction of diglycolic acid's ether group. Based on the above advantages of PBDT, the PLA/PBDT blends were prepared to improve the ductility of PLA. The blends' thermal, crystallinity, mechanical, and rheological properties and compatibility were characterized. The blends all showed greater elongation at break compared to PLA. The WAXD results showed that the tensile specimens of PBDT were semi-crystalline, and the tensile specimens of PLA and the blends were almost amorphous. The incorporation of PBDT caused the fracture behaviour of the blends to change from brittle to ductile behaviour. It is concluded that PBDT can effectively improve the ductility of PLA and the blend with 20 wt.% PBDT has high elongation at break (135%).