VISCOSITY PREDICTION OF NONPOLAR, POLAR, AND ASSOCIATING FLUIDS OVER A WIDE PPT RANGE FROM A MODIFIED SQUARE-WELL INTERMOLECULAR POTENTIAL MODEL

A theoretically based predictive model for calculating both liquid and gas phase viscosities has been developed by modifying a statistical m echanics viscosity model based on the square well intermolecular poten tial. The original theory was corrected to account for the assumptions of only two-body interactions and molecular chaos for velocities and the inadequacy of the square well potential. In addition, the modified model approaches a consistent low-density limit with improved dilute gas temperature dependence. The model parameters are obtained from gas and liquid viscosity data and generalized with corresponding states e xpressions and group contributions. Gas and liquid viscosities for a w ide variety of 174 nonpolar, polar, and hydrogen-bonding compounds are correlated with average deviations of 0.5 % and 1.8 % and predicted w ith average deviations of 2.2 % and 6.1 %, respectively.