Wilhelmy plate studies of carbon fiber/viscous fluid systems

Abstract The use of Wilhelmy plate techniques for studying the interactions of fibers with fluids of variable viscosity is discussed. The influence of hydrodynamic effects of force (F) VS. DEPTH (z) plots is interpreted on the basis of surface tension‐independent added terms of the constitutive equation of the Wilhelmy experiment. Wetting experiments using pseudoplastic fluids (polyethyleneglycol/water solution) show that viscoelasticity is indeed important in the interpretation of Wilhelmy plate experiments. The comparison of wetting experiments performed on untreated and plasma‐treated carbon fibers showed that at low stage speed and fluid viscosity, surface chemistry and morphology determines contact angles. At higher stage speeds and viscosities and advancing and receding angles are affected by surface chemistry‐independent and hydrodynamics‐dependent added contributions.