Viscosity and density of poly(ethylene glycol) and its solution with carbon dioxide at 353.2 K and 373.2 K at pressures up to 15 MPa

Few viscosity and density data have been reported for CO₂-poly(ethylene glycol) solutions, even though many vapor-liquid equilibrium data exist in the literature. In this work, viscosity and density of pure poly(ethylene glycol) (PEG, M = 3000, 8300, 20,000 g mol^-1) at atmospheric pressure were measured. Viscosities of PEG 3000 and PEG 8300 solutions with CO₂ were measured with a torsional vibrating viscometer at 353.2 K and 373.2 K over the range of CO₂ pressures from 5 MPa to 15 MPa. The densities of CO₂-PEG solutions were calculated with the perturbed-chain statistical associating fluid theory equation of state. From shear viscosity measurements, PEG 3000 and PEG 8300 were confirmed to be Newtonian and PEG 20000 was confirmed to be non-Newtonian. The viscosity reduction ratio for PEG solutions saturated with CO₂ was found to be independent of the PEG molecular weight (400 ≤ M ≤ 8300 g mol^-1). A simple equation is proposed that can correlate CO₂-PEG solution viscosity reduction ratio to within 0.08 in absolute units. The CO₂-PEG solution viscosities could be correlated with free volume models to within 14% using the fitted value of CO₂ occupied volume.