Preparation, characterization and properties of binary and ternary blends with thermoplastic starch, poly(lactic acid) and poly(butylene adipate-co-terephthalate)

Binary and ternary blends of thermoplastic starch (TPS), poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) were prepared using a one-step extrusion process. The concentration of TPS in both binary and ternary blends was fixed at 50 wt%, with the rest being PLA and PBAT. A compatibilizer with anhydride functional groups was used to improve the interfacial affinity between TPS and the synthetic polyesters. The addition of a small amount of compatibilizer greatly increased the mechanical properties of the blends. Mechanical properties of the blends exhibited a dramatic improvement in elongation at break with increasing PBAT content. Compared to the non-compatibilized blends, the morphology analysis of the blends showed that most of the TPS particles were melting and were well dispersed in the polyester matrix for the compatibilized blends. The water absorption data of the non-compatibilized blends increased more significantly than the compatibilized blends when PBAT content increased.