Solubility, swelling degree and crystallinity of carbon dioxide–polypropylene system

Solubilities are reported for carbon dioxide (CO2) in polypropylene (PP) at temperatures from 313.2 to 483.7 K and at pressures up to 25 MPa. Buoyancy corrections required in the data reduction were estimated with the Sanchez and Lacombe equation of state (S-L EOS). Solubilities of CO2 in molten state PP could be correlated to within 5% for both the S-L EOS and the group-contribution lattice-fluid equation of state (GCLF EOS). The change in crystallinity of rubbery state PP with CO2 dissolution into the polymer was predicted with the GCLF EOS and the solubility data under the assumption that CO2 could dissolve only in the amorphous regions. The trend of the estimated crystallinity with CO2 dissolution into the polymer was consistent with results in the literature.