In situ anionic polymerization and mechanical, thermal and morphological properties of toughened and volume-enhanced blends of poly(lactic acid)
摘要
Poly(lactic acid) (PLA) is known for its excellent overall properties and is widely used as a degradable material. However, PLA has poor toughness due to its inherent brittleness and low ductility. Poly(butylene adipate-co-butylene terephthalate) (PBAT) has good toughness and can be used to toughen PLA, while the poor compatibility between the two materials leads to ineffective toughening of PLA by PBAT, which needs to be modified by adding compatibilizers during processing. In this study, high-toughness PLA-based blends were prepared by in-situ polymerization using lactide as the reactive monomer and PBAT as the toughening agent, with the addition of industrial-grade epoxy oligomers ADR and PLA-PBAT-PLA triblock copolymers as solo or synergistic compatibilizers, to investigate the effects of ADR and PLA-PBAT-PLA on the compatibility and properties of PLA and PBAT. The inclusion of compatibilizers enhanced the interfacial bonding between PLA and PBAT and boosted the toughness of PLA/PBAT blends, and the addition of 0.15 wt% ADR or 0.15 wt% PLA-co-PBAT resulted in the impact strength of PLA/PBAT (75/25) blends reaching 150.09 kJ/m2 and 100.39 kJ/m2, respectively. The epoxy group of ADR reacted with the terminal hydroxyl or terminal carboxyl group of PLA and PBAT to form a chemical bond, which enhanced the melt strength and water absorption. PLA-PBAT-PLA forms a block structure between PLA and PBAT, which improves the fluidity and tensile strength of the blends. These findings provide fundamental data for PLA/PBAT compatibility studies and provide further development for PLA blend modification studies.