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85. "Adhesive Contact of a Membrane with a Hemispherical Indenter: Theoretical Analysis and Model Liquid System" Webber, R.E.; Cheng, W.D.W.; Shull, K.R., J. Adhesion, 82, 427 (2006).
The axisymmetric Laplace equation is solved numerically to extract contact-angle
data for a flat liquid/vapor interface contacting a submerged hemispherical
solid. The liquid=vapor interface is treated as a membrane, with a membrane
tension equal to the surface energy of the liquid. By measuring the vertical
displacement of the membrane and the projected contact area the membrane makes
with the hemisphere, the contact angle and correspondingly the driving force
for motion of the contact line can be measured. We show that characteristic
receding and advancing contact angles can be obtained by measuring the contact
radii formed upon initial contact between the interface and hemisphere and final
contact just prior to detachment of the interface, respectively. Use of the
technique is illustrated with a model experiment involving the contact of an
air=water interface with a poly(methyl methacrylate) surface.
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