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.