Solubility of supercritical CO2 in biopolymers PBAT and PHBV

As environmental concerns surrounding conventional plastics continue to grow, biodegradable alternatives such as polybutylene adipate terephthalate (PBAT) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) have been and are gaining attention as promising candidates for sustainable polymeric foams production. These bioplastics offer potential for use in environmentally friendly foaming processes, particularly when paired with supercritical carbon dioxide (scCO 2 ), a non-toxic and inert foaming agent. Understanding the solubility of CO 2 in these polymers is critical for optimizing the foaming conditions and material performance. In this work, the solubility of scCO 2 in PBAT and PHBV was experimentally determined over a temperature range of 373 K to 413 K and pressures up to 130 bar using a magnetic suspension balance (MSB). In order to interpret the results and estimate the degree of swelling, the Sanchez–Lacombe Equation of State (SL-EoS) was applied. Since the solubility of CO 2 can be influenced by the semi-crystalline nature of the polymers, a crystallinity correction was incorporated into the model to better reflect the interaction of CO 2 with the amorphous regions. This adjustment improved the agreement between experimental and calculated values, providing a more accurate representation of solubility behaviour. The developed model serves as a useful predictive tool for designing efficient and sustainable foaming processes using PBAT and PHBV. • An improved tool to predict the solubility of scCO2 in PBAT and PHBV is presented. • The Sanchez-Lacombe EoS is a good tool to predict the behavior of scCO2 in bioplastics. • Experimental data were modelled, corrected for polymer swelling and crystallinity. • The binary interaction parameter depends on both pressure and temperature.