Abstract
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.
