Abstract
Bikerman has proposed a relation between liquid drop weight M and sliding angle α when the drop slides down the slope.
(1) L; width of the drop, σl; surface tension of water. K is defined as a constant depending on both wetting and roughness. Kawasaki proposed equation (2) for Bikerman's K,
(2) β; Wenzel's surface roughness, θa θr; advancing and receding contact angle.
However the effect of surface roughness in these equations is not examined yet. The authors examined equation (1) and (2) using glass and polymer surfaces having different roughnesses.
The results show that these equations can be generally applicable to hydrophobic surfaces (glass coated with a fluorochemical, polystyrene and cellulose triacetate), but not to rather hydrophilic surfaces (polyvinylchloride and cellulose diacetate).
