Isotherms of the Molar Viscosity of Liquids and Fluids over a Wide Range of Pressures

Abstract

The results from investigating the relationship between the characteristics of viscous flows and pressure are presented. Multiple linear regression is applied to a set of viscosity data of different pure liquids and fluids over wide ranges of pressure and temperature. For compounds with simple molecular structure, the pressure dependences of viscosity are satisfactorily described by linear equations containing molar volume. For more complex molecules (including associated liquids), a regression equation containing molar volume and molecular packing density is proposed for estimating viscosity at high pressures. Experimental data from the literature are in good agreement with the viscosities calculated with the equations proposed for both fluids and liquids.