The effect of surface roughening of polymers on measured contact angles of liquids

Abstract

Equilibrium, advancing and receding contact angles for five different liquids have been determined on twelve commercial polymers after various surface roughening procedures. It was found that influences of surface roughening on contact angles disappear if the stylus surface roughness RA is < 0.1 μm. Surface roughening tends to increase observed contact angles, if the contact angle on the smooth surface is above 86°, whereas contact angles decrease if the contact angle on the smooth surface is below 60°. For contact angles on the smooth surface between 60° and 86°, surface roughening was found not to influence measured contact angles. These results show a broad similarity in the trend, predicted by the early Wenzel equation, describing the influence of surface roughness on contact angles, although of course the stylus surface roughness RA is not identical to the theoretical r-parameter in the Wenzel equation. © 1984.