Hysteresis, entrapment, and wetting angle in mercury porosimetry

Abstract

Intrusion—extrusion hysteresis in mercury porosimetry is shown to be due to the extrusion wetting angle differing from the intrusion angle. When correct extrusion wetting angles are used, second-cycle intrusion—extrusion curves are coincident and first-cycle intrusion—extrusion curves reflect only the fact that mercury is permanently entrapped. The distribution of the entrapped mercury volume as a function of pore radius is given for two samples. The work corresponding to the entrapment of mercury, the work associated with the change in wetting angle, and the work of extrusion are determined. These work terms were also identified with regions of hysteresis on first-and second-cycle intrusion—extrusion curves.