Influence of cooling rate during annealing on the microstructure and properties of Poly(butylene succinate) oriented films

Abstract

Annealing is a crucial technique for enhancing the structure and performance of polymer materials. The cooling step during annealing for polymer materials has frequently been underestimated. This study investigates how varying cooling rates during annealing impact the microstructure and properties of PBS-oriented films. Owing to the consistent annealing temperature, both two annealing processes exert similar effects on the main lamellae, which account for the majority of the crystalline fraction. Consequently, the thickness and lateral size of the main lamellae in both annealed samples are comparable, as are their lamellar orientation and crystallinity. The cooling rates during the cooling stage predominantly govern the metastable lamellae and RAF content. A slower cooling rate during annealing provides melted metastable crystals with an extended period to reorganize and form more perfect structures, thereby reducing their quantity. Furthermore, prolonged physical aging may constrain more amorphous phases, contributing to an increase in RAF content. The reduced metastable structure contributes to enhanced tensile modulus, tensile strength, and elastic recovery in AN-S samples. The increased RAF content enhances the oxygen barrier properties of the AN-S sample. This study demonstrates that selecting a slower cooling rate during annealing can significantly enhance the barrier and mechanical properties of PBS film, thereby expanding its potential applications.