REAL-TIME PENDANT DROP TENSIOMETER USING IMAGE-PROCESSING WITH INTERFACIAL AREA AND INTERFACIAL-TENSION CONTROL CAPABILITIES

Among different methods used for the measurement of interfacial tensio n, the pendant drop is particularly well adapted to liquid-liquid inte rfaces. Using an integrated form of Laplace's equation, we have develo ped an automatic pendant drop tensiometer which allows a real-time mea surement (i.e., three to five measurements per second) with an accurac y less than 0.1%. The very new feature of this tensiometer is the poss ibility of controlling the interfacial area and the interfacial tensio n during an experiment for the study of (i) adsorption processes at co nstant area or tension and (ii) the dynamical properties of the Marang oni effect for adsorbed layers. (C) 1996 Academic Press, Inc.