The solubility and diffusion coefficient of carbon dioxide in the biodegradable polymers poly(butylene succinate) and poly(butylene succinate-co-adipate) were measured at temperatures from 323.15 to 453.15 K and pressures up to 20 MPa. The solubilities in the polymer's molten state increased linearly with pressure and decreased with temperature. Solubilities could be correlated to within 2.2% by the Sanchez−Lacombe equation of state in conjunction with a temperature-dependent interaction parameter. The Sanchez−Lacombe equation of state was also found to be applicable to the correlation of solubilities in the semicrystalline state. The interaction parameter determined from fitting the solubility was inversely proportional to temperature. The diffusion coefficients of carbon dioxide showed a weak concentration dependence and had an order of magnitude of 10-9 m2/s in the molten state. The diffusion coefficients were correlated with the free-volume model of Kulkarni and Stern.

Pressure‐Volume‐Temperature (PVT) behavior of three biodegradable polymers, Polylactide, poly(butylene succinate), and poly(butylene succinate‐co‐adipate), was measured at temperatures from 313 to 493 K and pressures up to 200 MPa. The PVF data in molten state were compared with predicted values of a group contribution modified cell model equation of state (GCMCM EOS). It was found that the GCMCM EOS coupled with one specific volume datum at atmospheric pressure could predict the PVT of the polymer melts to within 0.46% in an average relative deviation of specific volume.

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