High Content of Thermoplastic Starch, Poly(butylenes adipate-co-terephthalate) and Poly(butylene succinate) Ternary Blends with a Good Balance in Strength and Toughness.

The ternary blends of a high content of thermoplastic starch (TPS), poly(butylenes adipate-co-terephthalate) (PBAT), and poly(butylene succinate) (PBS) were first melt-compounded in a twin screw extruder. The TPS contents in ternary blends were fixed at 60 wt%. The miscibility, morphology, thermal behavior, mechanical properties, and thermal resistance of the blends were investigated. The results showed that dispersions of PBS and PBAT minor phases improved the tensile strength and elongation at break. TPS/PBS/PBAT60/10/30 formed a good balance in strength and toughness. Dynamic mechanical analysis of the blends exhibits an intermediate and peak suggesting the ternary blend is compatible. Minor phase-separated structure SEM results showed that TPS/PBS/PBAT60/10/30 blend formed a typical mixture with core-shell morphology. As the PBAT composition was increased, phase morphology changes occurred in the blends, leading to decreased values of complex viscosity, storage modulus, and loss modulus. Moreover, the thermal resistances and melt flow properties of the materials were also studied by analysis of the heat deflection temperature (HDT) and melt flow index (MFI) value in the work.