The essential role of PBS on PBAT foaming under supercritical CO2 toward green engineering

Poly (butylene adipate-co-terephthalate) (PBAT) foams display serious shrinkage problems when supercritical CO2 is utilized as the blowing agent. In this work, a series of fully biodegradable PBAT/polybutylene succinate (PBS) foams were prepared by using supercritical CO2. The introduction of PBS improves the mechanical and crystallization properties. 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. Owing to the synergistic effect of the increased open-cell content and the improvement of stiffness, 80/20 blend of PBAT and PBS exhibited the highest expansion ratio of 18.4 without shrinkage. PBS plays multiple essential roles in the foaming and shrinking process with CO2 green blowing agent, providing a widely applicable anti-shrinkage strategy, which also affords shed light upon the large-scale preparation of the biodegradable polyester foams. •A series of fully biodegradable PBAT/PBS blending foams were prepared.•The increased crystallization degree decreased the CO2 diffusion, improving the shrinkage problem.•The presence of PBS could facilitate cell nucleation and increase CO2 solubility, preparing microcellular foam.•With higher stiffness and increasing open-cell structure, the shrinkage problem of PBAT foams was effectively solved.•80/20 blend of PBAT and PBS exhibited the highest expansion ratio of 18 without shrinkage.