Ductile polylactic acid/poly(butylene sebacate-co-terephthalate) blends: from structures to properties

Polylactic acid (PLA) is a kind of bio-based polyester with high tensile strength and poor ductility. Poly(butylene sebacate-co-terephthalate) (PBSeT) is a kind of biodegradable polyester with good ductility. To improve the ductility of PLA, PBSeT with high molecular weight was synthesized and melt blended with PLA to obtain PLA/PBSeT blends with high ductility in this study. Their structures and properties were characterized by differential scanning calorimetry, thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). Although SEM, DMA, and TGA suggested poor compatibility between PBSeT and PLA, PBSeT can still improve the ductility of PLA. When the PBSeT content was 30 wt%, the elongation at break of the blend increased to 85.9%. PBSeT debonds with the PLA matrix to form internal cavitation and the shear band to absorb a large amount of energy to induce plastic deformation. Meanwhile, PBSeT can reduce the complex viscosity of PLA.