Toward High Strength, Ductility, and Barrier Performance for Poly(glycolic acid)/Poly(butylene adipate-co-terephthalate) Green Films through Reactive Compatibilization and Biaxial Drawing

Polyglycolic acid (PGA) is considered a promising competitor in green packaging due to its superior strength and outstanding barrier properties, but its applications are limited by its inherent brittleness. Traditional toughening methods are usually accompanied by sacrifices in both strength and barrier properties. In this work, robust and high-barrier PGA/poly(butylene adipate-co-terephthalate) (PBAT) films were prepared by combining reactive compatibilization, biaxial drawing, and constrained annealing processes. The abundant uniformly oriented nanocrystals with the c-axis parallel to the film surface formed in biaxial drawing and constrained annealing increase the tensile strength as reinforcing elements and improve the barrier properties as a barrier wall. Biaxial drawing also induces a reinforced chain entanglement network, which facilitates the improvement of ductility. Importantly, reactive compatibilization plays a key role by increasing interfacial interactions to prevent cavitation and to maintain a robust entanglement network during annealing, consequently further improving the ductility and barrier properties of the films. As a result, the compatibilized PGA/PBAT biaxially drawn film (A-G/B/M-4) exhibits superior tensile strength (146 MPa), ductility (57%), and excellent oxygen barrier properties (OP = 0.54 × 10–15 cm3 cm cm–2 s–1 Pa–1). This work provides a potential route for preparing isotropic PGA-based films with superior comprehensive performance and deepens the understanding of the structure/property evolution of polymer blends upon biaxial drawing.