FORCED LIQUID MOVEMENT ON LOW-ENERGY SURFACES

The dynamic wetting and dewetting of polyethylene terephthalate (PET) by polar liquids (water and glycerol) has been studied. The solid was scanned by liquid movement at velocities, V, in the range 0.001-0.5 cm/s and the contact angle, θ, was determined by a tensiometric method. Broad agreement between tensiometric θ-V data and those obtained by other workers via optical techniques was found. The measured θ-V relationships were compared with those predicted by existing theories of wetting kinetics. The molecular-kinetic theory was found to be more adequate in this regard than the hydrodynamic theory. A number of issues remain unresolved, specifically the intrinsic reasons for the observation of multimechanism θ-V behavior and also the absence of low velocity convergence of the dynamic, particularly receding, contact angle to the static value. © 1993 Academic Press, Inc.