Wetting adhesional

In adhesional wetting, a liquid which is not originally in contact with the solid substrate makes contact and adheres to it. In contrast to spreading wetting, the area of liquid-gas interface decreases. The work (free energy) of adhesion is given by the Dupr6 equation (see equation (4.29) in the form... 

The process of wetting when a solid (or liquid) that is initially in contact with gas becomes completely covered by an immiscible liquid phase. See also Wetting, Spreading Wetting, Adhesional Wetting. 

Suppose that water is not originally in contact with the solid surface and adheres to it (i.e., adhesional wetting). When the drop of water is laid on a flat, smooth, solid surface, three forces are at work surface tension between the solid and air, ySA interfacial tension between the solid and water, ysw and surface tension between water and air, yWA. Incorporating only the horizontal components of these forces leads to ... 

Adhesional wetting (which we shall call adhesion and denote by subscript adh ) is a process by which an adhesional union is formed between two pre-existing surfaces (one of them being solid and the other liquid). Here, two initial interfaces (solid-gas and liquid-gas) are replaced by one (solid-liquid). 

Three types of wetting phenomena have been described adhesional wetting, spreading wetting,... 

Immersional wetting (fig. 5.8c) takes place if the solid is completely wet, that is, it is the result of spreading for S > 0 during the entire process, as in case (a). It is a less general phenomenon than adhesional wetting. It is noted that forced immersion of only partially wettable objects in a liquid leads in practice to the entrainment of air bubbles on the surface. 

Three types of wetting have been distinguished (Osterhuf, 1930) (1) spreading wetting, (2) adhesional wetting, and (3) immersional wetting. The equilibria involved in these phenomena are well known. 

Spreading Wetting The process of wetting in which a liquid, already in contact with a solid (or second, immiscible liquid) surface, spreads over the solid surface, thereby increasing the interfacial area of contact between them. See also Adhesional Wetting, Immersional Wetting, Wetting. 

Ablation, 728 Absolute viscosity, 728 Absorbance, 728 Absorption, 728 Activated carbon, 728 Adhesion, 728 Adhesional wetting, 728 Admicelles, 750 Adsorbate, 728 Adsorbent, 728 Adsorption, 728 Adsorption isotherm, 729 Advancing contact angle, 729 Aerosol, 729... 

Figure 6.2 The three stages in the wetting of a cube hy a liquid a) to (fc) adhesional wetting (hi to (c) immersional wetting (c) fo (d) spreading wetting...

FIGURE 17.9. Three types of wetting phenomena may occur, each with its own thermodynamic relationship. They are (a) adhesional wetting in which two surfaces make contact displacing a third phase, but without flow (Z>) spreading wetting, similar... 

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