Coalescence

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coalescence

[‚kō·ə′les·əns]
(botany)
The union of plant parts of the same kind such as the united sepals of flowering plants.
(metallurgy)
The bonding of welded materials into one body.
(meteorology)
In cloud physics, merging of two or more water drops into a single larger drop.
(physics)
The uniting by growth in one body, as particles, gas, or a liquid.

Coalescence

 

the fusion of drops or bubbles upon contact with each other in a mobile medium (liquid or gas) or on the surface of a body. It is accompanied by enlargement of drops (bubbles) and is brought about by the effect of forces of inter-molecular attraction. It is a spontaneous process accompanied by a decrease in the free energy of the system. As a result of coalescence, emulsions and foams may cease to exist as disperse systems and undergo complete separation into two macrophases, liquid-liquid or liquid-gas. In a liquid dispersion medium, coagulation frequently precedes coalescence. A special case of coalescence is known as self-adhesion, during which the interface between the agglutinating particles or fused lumps of the plastic polymer disappears as a result of slow diffusion of macromolecules.

Along with isothermal distillation, coalescence of water droplets causes the precipitation of atmospheric residue (rain or dew) from clouds and fog. The coalescence of droplets of paint or lacquer sprayed onto a surface to be painted leads to the formation of a continuous film. Coalescence is the basis of many other production processes and natural phenomena.

coalescence

The formation of a film of resinous or polymeric material when water evaporates from an emulsion or latex system, permitting contact and fusion of adjacent latex particles.