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

• Pure PEG 3000 and pure PEG 8300 densities and viscosities at 0.1 MPa.
• Viscosities of CO2–PEG 3000 solutions at (353.2, 373.2) K and (5, 10, 15) MPa.
• Viscosities of CO2–PEG 8300 solutions at (353.2) K and (5, 10) MPa.
• PEG viscosity reduction by CO2 independent of PEG molecular weight.
• Simple equation for CO2–PEG viscosity reduction ratio in terms of CO2 weight fraction.

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.

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