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The forces that cause adhesion and cohesion can be divided into several types. The intermolecular forces responsible for the function of various kinds of stickers and sticky tape fall into the categories of chemical adhesion , dispersive adhesion , and diffusive adhesion .
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.
Cohesion is the component of shear strength of a rock or soil that is independent of interparticle friction. In soils, true cohesion is caused by following: Electrostatic forces in stiff overconsolidated clays (which may be lost through weathering) Cementing by Fe 2 O 3, Ca CO 3, Na Cl, etc. There can also be apparent cohesion. This is caused by:
There is also a tension parallel to the surface at the liquid-air interface which will resist an external force, due to the cohesive nature of water molecules. [2] [3] The forces of attraction acting between molecules of the same type are called cohesive forces, while those acting between molecules of different types are called adhesive forces.
Most bioadhesives use polymers (carbohydrates and proteins) to create the adhesive and cohesive strength. [4] Natural adhesives used by both plants and animals are composed of only a few basic components, such as proteins, polysaccharides, polyphenols, and lipids that are mixed in various combinations. [4] Natural adhesive chemical and ...
As the adhesive solidifies, its internal strength, the cohesion, increases. The cohesion is also based on physical interactions, in this case between the adhesive polymers. In the case of adhesives which cure by a chemical reaction, i.e. the formation of polymers by a chemical reaction of the adhesive constituents, the resulting chemical bonds ...
The source of adhesive forces, according to the dispersive adhesion mechanism, is the weak interactions that occur between molecules close together. [2] These interactions include London dispersion forces, Keesom forces, Debye forces and hydrogen bonds. Individually, these attractions are not very strong, but when summed over the bulk of a ...
The attraction between the layers of the fluid is the result of cohesive forces, and viscosity is the property that explains the nature and strength of cohesive forces within a fluid. It is common to experience the fact that the flowing fluid will exert a certain amount of force on the plate, trying to pull it in its flow direction.