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The engineering principle behind chemical adhesion in this sense is fairly straightforward: if surface molecules can bond, then the surfaces will be bonded together by a network of these bonds. It bears mentioning that these attractive ionic and covalent forces are effective over only very small distances – less than a nanometer. This means ...
Conversely, a convex meniscus occurs when the adhesion energy is less than half the cohesion energy. Convex menisci occur, for example, between mercury and glass in barometers [1] and thermometers. In general, the shape of the surface of a liquid can be complex.
When cohesion dominates (specifically, adhesion energy is less than half of cohesion energy) the wetting is low and the meniscus is convex at a vertical wall (as for mercury in a glass container). On the other hand, when adhesion dominates (when adhesion energy is more than half of cohesion energy) the wetting is high and the similar meniscus ...
Cohesion allows for surface tension, creating a "solid-like" state upon which light-weight or low-density materials can be placed. Mercury exhibits more cohesion than adhesion with glass Rain water flux from a canopy. Among the forces that govern drop formation: cohesion, surface tension, Van der Waals force, Plateau–Rayleigh instability
The advancing contact angle can be described as a measure of the liquid-solid cohesion while the receding contact angle is a measure of liquid-solid adhesion. The advancing and receding contact angles can be measured directly using different methods and can also be calculated from other wetting measurements such as force tensiometry (aka ...
where 1 and 2 represent the two components in the composite or blend. When determining if two materials will adhere it is common to compare the work of adhesion with the work of cohesion, W coh = 2γ. If the work of adhesion is greater than the work of cohesion, then the two materials are thermodynamically favored to adhere.
Dispersive adhesion, also called adsorptive adhesion, is a mechanism for adhesion which attributes attractive forces between two materials to intermolecular interactions between molecules of each material. This mechanism is widely viewed as the most important of the five mechanisms of adhesion due to its presence in every type of adhesive ...
Adsorption is the adhesion [1] of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. [2] This process creates a film of the adsorbate on the surface of the adsorbent . This process differs from absorption , in which a fluid (the absorbate ) is dissolved by or permeates a liquid or solid (the absorbent ). [ 3 ]