Sustainable and high-performance ternary blends from polylactide, CO2-based polyester and microbial polyesters with different chemical structure

Herein, high-performance sustainable ternary blends were prepared via a melt blending method from completely biodegradable polyesters, namely commercial polylactide (PLA), poly(propylene carbonate) (PPC) and a series of poly(hydroxyalkanoate)s (PHAs), including poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3-hydoxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and two types of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) having different 3HB molar ratios. The miscibility, phase structure, mechanical and thermal properties of the blends were investigated to deeply understand the influence of the blend compositions and species of PHAs on the structure and physical performance of the multiphase blends. Thermal and morphological analysis revealed that the PLA, PPC and PHAs components showed partial miscibility with each other, especially the blend with P34HB of a low 3HB ratio. Remarkable enhancement in the ductility and toughness of PLA was gained by the addition of PPC and P34HB. An optimum tensile strain of 171% was achieved for the PLA/PPC/P34HB (60/30/10) blend, while PLA/PPC/P34HB (60/10/30) blend showed the highest impact strength with a value of 45 kJ m(-2), which is 14 times higher than that of PLA. Synergistic toughening from the flexible PPC and P34HB phase with a degree of interfacial compatibilization played an effective role in enhancing the mechanical performance of the ternary blends.