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Cohesion, along with adhesion (attraction between unlike molecules), helps explain phenomena such as meniscus, surface tension and capillary action. Mercury in a glass flask is a good example of the effects of the ratio between cohesive and adhesive forces.
Adhesion is the tendency of dissimilar particles or surfaces to cling to one another. (Cohesion refers to the tendency of similar or identical particles and surfaces to cling to one another.) The forces that cause adhesion and cohesion can be divided into several types.
Also, both the adhesion-forming interactions between adhesive and substrate, as well as the inter-intramolecular interactions causing the cohesion, can be adversely affected by external influences (including temperature, humidity, chemicals, radiation, mechanical stress). The degree of impairment depends on the nature of the conditions and ...
Contact angles greater than 90° (high contact angle) generally mean that wetting of the surface is unfavorable, so the fluid will minimize contact with the surface and form a compact liquid droplet. For water, a wettable surface may also be termed hydrophilic and a nonwettable surface hydrophobic. Superhydrophobic surfaces have contact angles ...
Cohesion may refer to: Cohesion (chemistry), the intermolecular attraction between like-molecules; Cohesion (computer science), a measure of how well the lines of source code within a module work together; Cohesion (geology), the part of shear strength that is independent of the normal effective stress in mass movements
The strength of adhesion depends on many factors, including the means by which it occurs. In some cases, an actual chemical bond occurs between adhesive and substrate. Thiolated polymers , for example, form chemical bonds with endogenous proteins such as mucus glycoproteins, integrins or keratins via disulfide bridges. [ 40 ]
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 ]
A powder is called free-flowing if the particles do not stick together. If particles are cohesive, they cling to one another to form aggregates.The significance of cohesion increases with decreasing size of the powder particles; particles smaller than 100 μm are generally cohesive.