SPREADING OF A LIQUID-FILM WITH A FINITE CONTACT-ANGLE BY THE EVAPORATION CONDENSATION PROCESS

Classical condensation and interfacial concepts like the Kelvin, Young-Dupre, and augmented Young-Laplace equations are used to develop a simple physical model of contact line motion for the finite contact angle case at relatively low velocity. Theoretical predictions of the velocity are compared with experimental data in the literature for the following three significantly different systems: octane on Teflon (apparent contact angle, theta(e) = 26-degrees) and methylene iodide on nylon (theta(e) = 41-degrees) obtained on flat surfaces and the capillary rise of water in a dehydroxylated glass capillary (theta(e) = 36-degrees). The results demonstrate that the evaporation/condensation process could have a significant effect on contact line movement in these systems at 293 K. We also find that the forced increase in the observable apparent contact angle could be an approximate measure of the condensation rate in the vicinity of the contact line and therefore contact line velocity due to condensation.