Determination of carbon dioxide solubility in polylactide acid with accurate PVT properties

• The solubility of CO2 in PLA and the PVT behavior of PLA were investigated.
• The solubility is directly proportional to pressure and inversely to temperature.
• Molecular configuration of the molecular chains did not effect on the solubility.
• The SS-EOS and the SL-EOS were used to determine theoretical solubility of CO2.
• The SS-EOS was found to be closer to the experimental results.

The solubility of CO2 in polylactide acid (PLA) and the pressure–volume–temperature (PVT) behavior of PLA were investigated using a magnetic suspension balance (MSB) and an in-house visualization device. Experiments were carried out at temperatures ranging from (453 to 473) K, and the pressure was varied from (6.89 to 20.68) MPa. The results indicated that as the temperature increased, the swelling and the solubility decreased, whereas increased pressure produced increases in swelling and solubility. The d-lactic acid content (d-content) did not have a pronounced effect on the solubility of CO2 or on the swollen volume of the PLA/CO2 mixture. We compared the theoretical and experimental swelling volume ratios and used the Simha Somcynsky (SS) equation of state (EOS) and the Sanchez Lacombe (SL) EOS to obtain the theoretical data.