Postulated role of intrinsic contact-angle hysteresis in mercury porosimetry

Abstract

Mercury-porosimetry hysteresis, previously recognized to be related to contact-angle hysteresis, is equivalent to the irreversibility of the work cycle of immersion followed by emersion of the surface of a sample by mercury. There are several implications to recognizing that this work cycle is irreversible. For example, the validity of surface areas calculated from this pressure—volume work requires examination. Several past models for mercury-porosimetry hysteresis and for contact-angle hysteresis are also examined. The conclusion reached in the present work is that irreversible work is converted to heat in a manner that is completely analogous to friction. Regardless of the direction of motion, a portion of the mechanical work involved in moving the three-phase boundary is converted to heat, even if the surface is smooth and homogeneous. This intrinsic contact-angle hysteresis may be present not only in the mercury-porosimetry experiment, but also for other contact-angle phenomena, such as measurements involving sessile droplets.