EFFECT OF PLUNGING TAPE SURFACE-PROPERTIES ON AIR ENTRAINMENT VELOCITY

The wettability of polymeric tape surfaces such as polystyrene, polyethylene, and polypropylene does not significantly affect air entrainment velocities. However, rougher surfaces, aa suggested by L. E. Scriven, shown significantly higher air entrainment velocities. This work was carried out to study the effects of surface wettability and roughness on air entrainment velocities. Although the data show more scatter than one would like, it is very clear that the rough surfaces of the uncoated sides of the paper tapes and the rough surface polyethylene coated paper show significantly higher air entrainment velocities than do the smoother tapes. The air entrainment velocities seem to increase with root mean square roughness. This agrees with the suggestion of Scriven that near the dynamic wetting line with rough surfaces, air can 'escape' through the valleys between peaks in the surface.