Young-Dupr6 equation

This relation is known as the Young-Dupr6 equation. It shows that the energy of adhesion can be determined by measuring the contact angle and the surface... 

The contact angle between water and glass is increased considerably by even less than an adsorbed monolayer of greasy material such as fatty acid. Wa is decreased, since some of the glass-water interface is replaced by hydrocarbon-water interface (Figure 6.4a) hence, from the Young-Dupr6 equation, 0 increases. 

Wg = W g. Equation 8 is generally applicable but, for low energy solids and liquids which display a finite contact angle. Equation 9 may be used to calculate the free energy of cohesion (from Eq. 8 and Eq. 3, i.e. the Young-Dupr6 equation). 

The classical analysis of Young and Laplace of static wetting problems rests on the characterization of each interface by a macroscopic surface tension. At the intersection of three bulk phases, the three phase contact line is at rest only if the capillary forces represented by these surface tensions balance. When the three phases are a solid substrate S, a wetting liquid L and a vapor V, the mechanical equilibrium condition parallel to the solid gives the Young-Dupr6 equation for the contact angle Oq... 

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