CONTACT-ANGLE HYSTERESIS ON HETEROGENEOUS SMOOTH SURFACES - THEORETICAL COMPARISON OF THE CAPTIVE BUBBLE AND DROP METHODS

A theoretical comparison is presented between two approaches to the me asurement of contact angle hysteresis, i.e. the drop and the captive b ubble methods. It is shown that major differences in the dependence of the measured contact angle on volume may exist between the drop and t he captive bubble systems. These differences are exhibited in relation ship with the behavior during the ''slip'' and ''stick'' stages, the a mplitude of contact angle oscillations, and the wavelength of these os cillations. (C) 1998 Elsevier Science B.V.