Investigations of the effects of molecular structure and chemical composition on the Newtonian shear viscosities of simple molecular liquids : hexanes and pentanols

Abstract

Relative kinematic viscosities of fifteen purity-characterized liquids were measured at temperatures ranging from -18. to 80. °C. The experimental procedure was designed to manipulate high purity samples, utilizing standard Cannon-Ubbelohde suspended-meniscus viscometers, a novel high-precision time of efflux technique, and platinum resistance thermometry. High precision kinematic viscosity measurements for selected high purity isomeric hexanes and pentanols indicate that for these simple molecular liquids, viscosity is a sensitive function of purity. The systematic experimental error indicated by inconsistent literature data is quite probably due, in large part, to this effect. A generalized empirical function that reduces, for specific values of its adjustable parameters, to several previously proposed equations for the temperature dependence of viscosity was examined. This generalized equation, in a reduced three-parameter form, was shown to be exceptionally versatile as a viscosity data-fitting equation. The utility of this equation for empirical characterization of experimental viscosity data over extended temperature ranges was demonstrated. ...