Annealing improves the mechanical properties in poly(butylene succinate) films with oriented lamellar structure: The effect of metastable lamellae

Abstract The application range of biodegradable Poly(butylene succinate) (PBS) is highly dependent on its mechanical properties, which can be improved by the annealing process. In this study, the mechanical properties and microstructure of PBS films with oriented lamellar structures annealed at different temperatures were characterized. It was found that the annealing process effectively improves the elastic modulus and yield strength of the oriented PBS film with the increase of annealing temperature, which is completely different from the previous results of other oriented semicrystalline polymers such as PP, PMP, PE, and PVDF. The long periods, lateral dimensions and orientation of the lamellae of the oriented PBS film increase with the increasing annealing temperature. Meanwhile, the low‐temperature endothermic plateau in the DSC curve and the g 1,r/ Q in the SAXS experiment decrease with annealing temperature, indicating that increasing annealing temperature would reduce the thin and metastable lamellae in the PBS films. Compared the annealing results of oriented PBS films and that of other‐oriented semicrystalline polymers, we suggested the annealing process for the oriented PBS films would reduce the thin lamellae and form thicker lamellae, resulting in an increase in the elastic modulus and yield strength of the annealed PBS films. This study clarifies how the annealing temperature affects the microstructure and mechanical properties of the oriented semicrystalline films.