VISCOSITY AND INTERNAL-PRESSURE FOR LIQUIDS

Based on Eyring's model of viscous flow, a relation between viscosity and internal pressure for liquids is established by thermodynamic method [GRAPHICS] where nu is frequency with which activated molecule falls in the hole; alpha is a parameter related to the ratio of heat absorbed to energy required for forming a hole in liquids. Both are characteristic constants of liquids. The Eyring's viscosity formula can be derived from this relation by introducing some approximants. But it is necessary to assume the size of hole just equals the volume occupied by a molecule, rather than one-third the volume of a molecule as considered by Eyring and his collaborators. The mechanism and activated energy for viscous flow of liquids are discussed in accordance with this result.