CONTROLLED DROP TENSIOMETER FOR MEASURING DYNAMIC INTERFACIAL AND FILM TENSION

A dynamic interfacial tensiometer described measures the tension of st ressed liquid-liquid interfaces. In this accurate and controlled metho d, the time-dependent pressure difference across the curved interface of a spherical drop, immersed in a second immiscible phase, is measure d as a function of time. Dynamic experiments are conducted by varying the drop size, thereby stressing the interface. The technique is emine ntly suited for the measurement of static and dynamic interfacial tens ions, the study of the diffusion, adsorption, and desorption kinetics of surfactants, and the rheological behavior of liquid films. These ca pabilities ave demonstrated for n-dodecane contacted with an aqueous s olution of a nonionic surfactant. To explain the phenomena, diffusion models are developed that compare well with the experimental data. The noninvasiveness and versatility make this instrument a useful tool.