emulsion


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Related to emulsion: emulsifier, Emulsifying agent

emulsion:

see colloidcolloid
[Gr.,=gluelike], a mixture in which one substance is divided into minute particles (called colloidal particles) and dispersed throughout a second substance. The mixture is also called a colloidal system, colloidal solution, or colloidal dispersion.
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Emulsion

 

a disperse system consisting of droplets of a liquid (the dispersed phase) distributed evenly throughout another liquid (the dispersion medium).

A distinction is made between emulsions of the oil-in-water type (with droplets of a nonpolar liquid, such as a mineral oil, dispersed in a polar medium, usually water) and reverse emulsions of the water-in-oil type (with droplets of a polar liquid in a non-polar medium). Multiple emulsions are also encountered, in which the droplets of the dispersed phase serve as the dispersion medium for even finer droplets of another dispersed phase.

Emulsions are also divided into lyophilic and lyophobic types (seeLYOPHILIC AND LYOPHOBIC COLLOIDS). Lyophilic emulsions are thermodynamically stable, reversible systems that are formed spontaneously at temperatures close to the critical displacement temperature for two interacting liquids. Lyophobic emulsions are thermodynamically unstable systems formed by the mechanical, acoustic, or electrical dispersion of one liquid in another or by the separation of droplets from a supersaturated solution or melt; such emulsions may exist for prolonged periods only if mixed with an emulsifier. Lyophilic emulsions are highly dispersed (colloidal) systems, the droplets of which measure no more than 10–5 cm. Lyophobic emulsions are coarsely (poorly) dispersed systems with droplet size usually ranging from 10–5 to 10–2 cm. If the dispersed phase and dispersion medium differ greatly in density, the emulsion will be kinetically unstable—that is, the particles of the dispersed phase will tend either to sink to the bottom or rise to the top. The sedimentation of emulsion droplets that are well protected against coalescence may lead to the concentration of the droplets and the formation of creams or sediments of continuous two-liquid phases not separated into discrete layers.

The type and properties of an emulsion depend on such factors as its composition, the relative proportions of the liquid phases, the quantity and chemical nature of the emulsifier, the method of emulsification, and the temperature at which the emulsification is carried out. A change in the composition of an emulsion or in the action of the emulsifier may produce a phase inversion, in which an oil-in-water emulsion becomes a water-in-oil emulsion or vice versa.

Dilute emulsions are typical liquids, with droplets that move freely and independently of one another in a highly mobile medium. In emulsions with droplets of uniform size, as the concentration of the dispersed phase exceeds 74 percent by volume, the viscosity of the system increases abruptly, and the emulsion becomes a gel. In the process, droplets that initially had a spherical shape are highly deformed in such a way that they come to resemble polyhedrons. The content of the dispersed phase in highly concentrated emulsions may be as high as 99 percent by volume; in such cases, the dispersion medium is retained between the droplets in the form of fine layers that resemble the liquid films between bubbles in foams.

Emulsions with various compositions and properties are commonly used in industry, agriculture, and medicine; they also have household uses. Many foods, such as milk and egg yolks, are multicomponent emulsions, as are unrefined petroleum and the milky juices of plants.

Among the products that take the form of emulsions are cooling lubricants and various pesticides, cosmetics, drugs, and binders for latex paints. Asphalt emulsions are used in construction.

REFERENCES

Voiutskii, S. S. Kurs kolloidnoi khimii, 2nd ed. Moscow, 1975. Pages 367–81.
Emul’sii. Leningrad, 1972. (Translated from English.)
Becher, P. Emulsions: Theory and Practice, 2nd ed. New York, 1965.
Emulsions and Emulsion Technology, parts 1–2. Edited by K. J. Lissant. New York, 1974.

L. A. SHITS

emulsion

[ə′məl·shən]
(chemistry)
A stable dispersion of one liquid in a second immiscible liquid, such as milk (oil dispersed in water).
(graphic arts)
In photography, the photosensitized material on film, plates, and various photographic papers.

emulsion

1. A mixture of liquids insoluble in one another, in which one is suspended in the other in the form of minute globules.
2. A mixture in which solid particles are suspended in a liquid in which they are insoluble, as a mixture of bitumen and water, with uniform dispersion of the bitumen globules. The cementing action needed in roofing and waterproofing takes place as the water evaporates.

emulsion

emulsionclick for a larger image
A suspension of a light-sensitive silver salt, especially silver chloride or silver bromide in a colloidal medium—usually gelatin—which is used for coating photographic films, plates, and paper.

emulsion

1. Photog a light-sensitive coating on a base, such as paper or film, consisting of fine grains of silver bromide suspended in gelatine
2. Chem a colloid in which both phases are liquids
3. a type of paint in which the pigment is suspended in a vehicle, usually a synthetic resin, that is dispersed in water as an emulsion. It usually gives a mat finish
4. Pharmacol a mixture in which an oily medicine is dispersed in another liquid
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The Prominent Players Operating In The Acrylic Polymer Emulsion Market include Celanese Corporation (U.S), Kamsons Chemicals Pvt.
This research was carried out using a Grant-in-Aid for Scientific Research (S) from the Japan Society for the Promotion of Science for the project "Cosmic gamma-ray observation by balloon borne emulsion telescope to study unsolved issues" (Representative: Shigeki Aoki, Research Project Number: 17H06132).
During the design of this experiment, we expected that the properties of the interfacial membranes of oil droplets would affect the storage stability of [alpha]-tocopherol incorporated in emulsions. Although there is a lack of information about the influence of the density of interfacial membranes on the oxidative stability of emulsified oils and the storage stability of encapsulated functional lipophilic compounds, according to previous studies, the emulsion interfacial thickness could be one of the important determinants of the oxidative stability of food emulsions [16].
The specific objectives of the current study are to investigate the influence of the Egg Albumin on the texture and the shelf life of O/W emulsion. The results of the current may be used to design the food products such as sauce, dressing and mayonnaises.
The emulsion must be over-oiled, this can lead to problems with the emulsion and creation of both carbon monoxide (CO) and nitrous oxides (NO).
Step 3 Incorporation of emulsion into gel base with continuous stirring.
This emulsion basically has oil as a continuous phase and is called an 'inverse' emulsion wherein water droplets remain as a dispersed phase.
BME has also made progress in helping customers address the challenges created by reactive ground, by developing a specialized emulsion for use in these conditions.
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Western Emulsions said the acquisition will allow it to offer its range of emulsion products to public agency customers throughout the Pacific Northwest and northern California for their roadway construction, preservation, and recycling programmes.