Green fabrication of ultralight and shrink-resistant biodegradable poly (butylene adipate-co-terephthalate)/poly (butylene succinate) foam using supercritical CO2 with ultrafast degradation

Abstract

The biodegradable polymer poly (butylene adipate-co-terephthalate) (PBAT) encounters challenges such as shrinkage and low expansion ratios using supercritical fluid foaming. In this work, poly (butylene succinate) (PBS) improves the stiffness and crystallinity of PBAT, while the introduction of ADR improving the crystallinity and rheological properties of PBAT/PBS blend. Maintaining ADR at 1.2 wt%, the increase in PBS content significantly enhances the crystallinity and Young’s modulus of PBAT increasing from 8.4 % to 25.3 % and from 46.6 MPa to 186.7 MPa, respectively. In the foaming process, PBS causes the deterioration of melt strength, promotes the cell nucleation, and decreases the cell wall thickness, facilitating the formation of open cell structure. Maintaining PBS content at 40 wt%, increased ADR enhances the crystallinity of PBAT/PBS from 19.9 % to 25.3 %, and the melt viscoelasticity of PBAT/PBS is significantly improved. Owing to the synergistic effects of increased crystallinity, stiffens, melt viscoelasticity and open cell structure, a foam with an expansion ratio of 33.9 was successfully prepared at a mass ratio of PBAT, PBS, and ADR of 60:40:1.2 (T60S40-R1.2), without encountering shrinkage issues. The degradation capability of T60S40-R1.2 foam was investigated and compared with that of pure PBAT foam, demonstrating superior degradation performance. This work proposes a potential strategy for developing eco-friendly PBAT/PBS foam with no shrinkage issues, high expansion ratio and ultrafast degradation.