Published online by Cambridge University Press: 28 February 2011
A quasi-equilibrium model is developed for capillary condensation flow, in which surfacediffusion is included. The model is in excellent agreement with the experimental data for the flow of toluene in untreated Vycor glass and in Vycor glass whose pores were derivatized with C18H38. The observed increase in viscosity with decreasing pore size is ascribed to a stagnant monolayer adsorbed to the pore walls. The surface diffusion coefficient at 22ºC is 5 x 10-5 cm2/secfor both the derivatized and untreated samples.