DYNAMIC INTERFACIAL-TENSION MEASUREMENTS BY A CAPILLARY-PRESSURE METHOD

A new technique to measure dynamic interfacial tension is presented wh ich represents one of the possible applications of the capillary press ure methods. These methods are based on the direct measurement of the capillary pressure to obtain surface or interfacial tension data by th e application of the Laplace equation. The particular approach (expand ed drop technique), presented with the relevant experimental details, allows the dynamic interfacial tension of static interfaces (constant interfacial area) to be recorded, as a function of the surface age. Th is latter property, together with the large mass of data which is poss ible to collect in a single experiment, makes this technique very attr active in adsorption kinetics studies aimed both at obtaining new expe rimental data and to test the available theories on the subject. A spe cific application to the study of adsorption kinetics of Triton X-100 at the n-hexane/water interface is also presented. The results of this study show that for this system adsorption kinetics is, essentially, diffusion-driven. Moreover, these results are in good agreement with t he available literature, confirming the reliability of the presented t echnique. (C) 1995 Academic Press, Inc.