Biodegradable blends of poly(butylene adipate-co-terephthalate) and stereocomplex polylactide with enhanced rheological, mechanical properties and thermal resistance

The aim of this study was to prepare a new blend system by blending equimolar poly(L-lactic acid) (PLLA) and poly(D-lactide acid) (PDLA) with poly(butylene adipate-co-terephthalate) (PBAT) and to form stereocomplex polylactide (sc-PLA) during blending process. Then, sc-PLA would improve the performance of PBAT without compromising its biodegradability. Torque-time curve, differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD) measurements indicated that only sc-PLA formed in PBAT matrix. The phase morphology showed that sc-PLA particles were uniformly dispersed in PBAT matrix, and the sizes were independent of their contents. The rheological properties of PBAT were significantly enhanced by addition of sc-PLA, especially after the formation of a percolation network structure. With the increase of sc-PLA content, the blends displayed increased yield strength and modulus and decreased elongation at break and tensile strength. The sc-PLA particles could reinforce PBAT matrix. Compared with pure PBAT, the heat resistance of PBAT/sc-PLA blends was improved.