Strong, ductile and durable Poly(glycolic acid)-based films by constructing crystalline orientation, entanglement network and rigid amorphous fraction

Poly(glycolic acid) as a promising substitution for traditional petroleum-based polymers suffers from its inherent brittleness and rapid hydrolysis. The improvement of toughness and hydrolysis resistance is usually accompanied with a sacrifice of strength and stiffness. In the present work, we propose a simple and effective strategy to address this obstacle by introducing poly (butylene adipate-co-terephthalate) (PBAT) and combining extensional stress and temperature field. The robust, ductile and durable PGA/PBAT films are fabricated via "high temperature melting-quenching-stretching-annealing" (QSA) process. Highly oriented crystallites constructed by stretching and annealing lead to the improvement of strength and stiffness. Stress-induced strengthened entanglement network contributes to stabilization of craze growth and slipping, thus leading to the ductile behavior. As the result, the QSA films exhibit 89 MPa and 131% in tensile strength and the elongation at break, which are increased by 195%, 126% respectively compared to the unstretched film. More impressively, stretching resulted in abundant rigid amorphous chains, which worked with oriented crystallites to impart enhanced heat and hydrolysis resistance for the films. This work paves an avenue toward a wider range of applications for PGA materials and might be guidance for other semi-crystalline polymer blends.