The Thermodynamic Characterization of Wetting by Submitting a Sessile Drop to Microgravity

A new technique, the sessile drop accelerometry (SDACC) for the study and measurement of the interfacial energies of solid-liquid-gas systems is tested and discussed in this study. The instrument –a combination of a goniometer with high speed camera and a laboratory drop tower- and the evaluation method, were designed to evaluate the interfacial energies as a function of the geometrical changes of a sessile drop shape due to the effect of “switching off” gravity during the experiment. The method bases on the thermodynamic equilibrium of the system interfaces and not on the balance of bi-dimensional tensors on the solid-liquid-gas contour line. A comparison of the model with the widely accepted Young`s equation is discussed in this study.