Measurement of CO₂-Induced Polymer Swelling and Predictability of Sanchez-Lacombe Equation of State for the Density of Polymer/CO₂ Systems

抄録

When carbon dioxide (CO₂) dissolves into polymer, polymer swelling occurs, i.e., the density of the polymer decreases. In this study, the densities of poly(ethylene glycol) (PEG)/CO₂ and polyethylene (PE)/CO₂ systems were measured gravimetrically at 200°C under different levels of CO₂ pressures in the range from 0 to 13 MPa. A magnetic suspension balance was used for the measurements where a thin disc-shaped platinum plate, density and volume of which are known for any temperatures and pressures, was immersed into the molten polymer/CO₂ single-phase systems. When the platinum is immersed in a molten polymer, the weight of the platinum is less than the true value owing to the buoyancy of polymer/CO₂. Thus, measuring the weight of the platinum immersed in polymer under the different CO₂ pressures could give the density change in the polymer/CO₂ system against the dissolved CO₂ concentration. The measured density data were used for evaluating the predictability of Sanchez-Lacombe Equation of State.