Relationship Between Microstructure and Performance of Biaxially Stretched Poly(Butylene Succinate)/Poly(Butylene Adipate‐ co ‐Terephthalate) Blended Films

ABSTRACT Poly(butylene succinate) (PBS) is a biodegradable polymer. It is often blended with poly(butylene adipate‐ co ‐terephthalate) (PBAT) to improve its elongation at break. However, poor tensile strength and barrier properties still limit its wider application. In this study, PBS/PBAT blend films were prepared by melt blending, casting, and simultaneous biaxial stretching. The mechanical properties, microstructure, barrier properties, and crystallinity of the films were characterized. The results show that the orientation of the PBS/PBAT film's cross‐sectional structure along the parallel film surface becomes more pronounced, and the crystallinity of the film also progressively increases with the increasing biaxial stretching ratio. The increase in crystallinity and the development of a two‐phase oriented structure in the PBS/PBAT blend led to an improvement in the tensile strength, elastic modulus, and barrier properties of the film, as well as a reduction in elongation at break. When the stretching ratio reached 4 × 4, the tensile strength and elastic modulus of the blend containing 30wt% PBAT increased by more than 150% and 81%, respectively. The elongation at break reached 260%, which is nevertheless twice that of pure PBS after biaxial stretching under identical conditions. These results indicate that blending and simultaneous biaxial stretching can significantly enhance the mechanical strength, toughness, and barrier properties of PBS‐based films.