Fully biobased strong and tough PLLA/PA510 blends: Fining phase morphology and robust interfacial adhesion through interface reaction modulation

Blend modification of bio-based flexible polymers with Poly (L-lactic acid) (PLLA) is a highly promising approach to improve the inherent brittleness of PLLA, which has, significantly restricted its practical applications. However, the realization of high flexibility while maintaining comparable strength remains a critical challenge due to the paradoxical nature of the polymer. To address this limitation, this study introduces a high-performance bio-based polyamide (PA510) for the first time, in conjunction with an epoxy compatibilizer (ADR), to achieve a balance of strength and toughness through interfacial and microstructure modulation. The theoretical predictions are carried out to guide the processing, and due to the affinity of ADR with PLLA, the migration of ADR and its pre-grafted products to the interface is promoted by premixing ADR with PA510, thus constructing PLLA-g-PA510 branched copolymers at the interface. The joint effect of robust interfacial adhesion and substantially reduced particle size of the dispersed PA510 phase (0.4 μm) enables the (PA510/ADR)/PLLA blends to simultaneously achieve high ductility and strong tensile strength. Its elongation at break is as high as 404.2%, while the tensile strength is comparable to that of pure PLLA at 59.6 MPa.