COLL 18 |
| Much of the research effort in studying the drop volume dependency of equilibrium contact angle has been focused on solid-liquid-vapor systems. The classical Young's equation has been modified in the literature to include a line tension term to explain this dependency. However, there appears to be some confusion about the magnitude and sign of this line tension. Here in this paper, we explore the possibility of applying the modified Young's equation to solid-liquid-liquid systems of interest in petroleum reservoir engineering. We present three different S-L-L systems, one with no adhesion, another with strong adhesion and the third exhibiting an intermediate behavior between the two extremes. The effect of interfacial adhesion on drop profiles and on equilibrium contact angle are presented as the volume of the drop phase was altered. An effort to apply the modified Young's equation to these three systems reveals that the line tension concept could indeed be applicable to S-L-L systems also. However, the magnitude of the line tension was found to be several orders of magnitude higher than those reported for S-L-V systems. This could perhaps be due to the large variation in contact angles (from 30o to 150o) observed with drop volume in our study while the literature studies deal with small changes (from 2o to 10o) in contact angles. Our results seem to indicate that the extent of deviation from the Young's equation exhibited by S-L-L systems may be directly related to the adhesion phenomenon. |
|
Chemically and Topographically Textured Surfaces
8:30 AM-12:00 PM, Sunday, August 19, 2007 BCEC -- 153A, Oral
Division of Colloid & Surface Chemistry |