Effect of Poly(butylenes succinate) on Poly(lactic acid) Foaming Behavior: Formation of Open Cell Structure

Biodegradable poly­(lactic acid) (PLA) based poly­(butylenes succinate) (PBS) foams with open cell structure were prepared via batch foaming method using supercritical carbon dioxide as blowing agent. It was found that PLA was immiscible with PBS, and PBS phase was dispersed as tiny spheres or large domains at various concentrations. The addition of PBS reduced the viscosity of the blends. During the foaming process, the PLA/PBS interfaces acted as cell nucleation sites and the low melt strength PBS contributed to the formation of cell connection channels, which resulted in open cell structure. The investigation of PBS content and foaming temperature found that PLA/PBS (80/20) foamed at 100 °C, obtaining the highest cell opening rate (96%). Two-step depressurization foaming experiments proved that bimodal cell structure PLA/PBS foams with high cell opening rate (97%) were able to be fabricated.