Investigation of the percolation transition in a nonwetting liquid-nanoporous medium system

The flows of liquid into and out of a nanoporous medium are studied as processes leading to the fluctuation formation and the growth of fractal clusters of filled and empty pores, respectively. The conditions for stable growth of such fluctuations are analyzed as a function of the interfacial energy between the liquid and the porous medium and the surface energy of the liquid. Expressions are obtained for the pressure at which the barrier for fluctuation filling and emptying of the pores vanishes. In general, it is shown for porous media with a pore-size distribution that these processes can be interpreted as a percolation phase transition. The volume and susceptibility of a liquid-porous medium system near the transition points with inflow and outflow of the liquid are calculated. The phenomenon of nonoutflow of a nonwetting liquid from a porous medium and hysteresis of the flow of liquid into and out of a porous medium are explained on the basis of the mechanism considered. The results of an experimental investigation of these processes in the system liquid Wood's alloy-silochrome 80 and silochrome 120 are presented. The experimental data obtained can be described on the basis of the proposed mechanism. (C) 2000 MAIK "Nauka/Interperiodica".