Viscosity experiments

“All viscosity experiments carried in this work were undertaken at 25 °C in an Anton Paar MCR rheometer with a double gap measuring cell (Evjen et al., 2019Hartono et al., 2014Skylogianni et al., 2019). This apparatus operates at atmospheric pressures. The double gap cell is filled with about 3.6 mL of solvent and semi-closed, so that there is little contact between the solution and the surrounding air and chemical stability can be assumed (i.e. there is negligible loss of CO2 to the atmosphere even in loaded solutions). Once the liquid is enclosed, a rotor is set in motion. The shear rates in the standard operational procedure vary between 10 and 1000 s−1. A computer connected to the equipment records shear stress versus shear rate values, producing the dynamic viscosity as the slope between these two variables. Hartono et al. (2014) have reported confidence intervals of ±2% for the dynamic viscosities obtained with this procedure, an interval that we assume to be valid for our data as well.

The loaded solvents evaluated in the Section 3.4 were obtained by preparing a fresh solution, loading part of it with CO2 up to values above 0.5 molCO2 molMEA−1 and then mixing loaded and fresh solvent in different proportions. After these partially loaded solutions are prepared, they are analytically titrated through the methods explained in Section 2.5. The values reported for the loadings are the values obtained analytically.”

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