Modified Eyring viscosity equation and calculation of activation energy based on the liquid quasi-lattice model

Abstract

Viscosity is an important physical parameter of fluid, and the Eyring viscosity equation is a popular viscosity theory. Based on the Eyring reaction rate equation and Boltzmann statistical theory, and including the probabilities of creating a hole in liquid and the transition to the neighboring hole, a modified Eyring viscosity equation was proposed. According to the structural characteristics of short-range order, liquid is treated as a quasi-lattice structure in a small region. The activation energy, which is the minimum energy needed for the molecule to jump to its neighboring hole because of the restriction of other molecules around it, was analytically calculated from an intermolecular Lennard-Jones potential function and a Stockmayer potential function. The viscosity values of 37 kinds of typical liquids at 25°C and the dependence of viscosity of three kinds of liquids on temperatures were calculated with this modified viscosity equation, and the calculated results agree with the experimental values to some extent. This work not only enriches the understanding of the mechanism of liquid viscosity, but also could provide some theoretical guides for the relevant studies and applications.