swelling


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swelling

an abnormal enlargement of a bodily structure or part, esp as the result of injury

Swelling

 

an increase in volume of solid bodies caused by their absorption of liquids or vapors from the environment. The capacity to swell is a characteristic property of bodies consisting of macromolecular compounds (polymers). Swelling is caused by diffusion processes, which are usually accompanied by solvation (the binding of a low-molecular-weight substance by a polymer).

A distinction is made between limited and unlimited swelling. In the first case the macromolecules are bonded fairly strongly, and swelling stops after having reached a certain limit. The swelled body retains its shape and a distinct boundary with the liquid phase. In the second case, mutual diffusion of the solvent and the polymer gradually leads to the disappearance of the interphase boundary between the swelling body and the liquid. Such swelling culminates in complete dissolution of the polymer. For example, limited swelling is exhibited by gel-like ion-exchange resins in water and by vulcanized rubber in benzene; unlimited swelling is exhibited by all polymers that are soluble in a particular solvent. In some cases, such as the gelatin-water system, limited swelling gives way to unlimited swelling with increasing temperature. Swelling is also a property of some minerals with a lamellar crystal lattice—for example, the montmorillonites. Upon swelling in water, such materials may undergo spontaneous dispersion, leading to the formation of highly disperse colloidal systems.

Swelling has wide use in industry and in everyday life. It frequently accompanies bonding of polymer materials, processing of polymers to produce various articles, production of rubber adhesives, and other processes, such as preparation of many foods and many natural processes (germination of seeds and spores).

REFERENCES

Tager, A. A. Fizikokhimiia polimerov. 2nd ed. Moscow, 1968. Page 314.
Voiutskii, S. S. Kurs kolloidnoi khimii. Moscow, 1964. Page 482.

L. A. SHITS

swelling

The volume increase caused by wetting, absorption of moisture, or chemical changes.
References in periodicals archive ?
This paper reports a new preparation methodology and swelling characterization of poly (Sodium acrylate-co-acrylamide).
"The swelling was that bad it went up into my nose and it closed my throat and nose.
"The system, which is also connected to a mobile phone application, detects the bacterial infections and swelling in their early stages and can alert the doctor for a quick follow-up and treatment, which prevents them from spreading to other body parts," he said.
Turmeric not only helps to fight the inflammation, but also reduce swelling and pain, and rest the muscle so it can treat sprained ankle effectively.
High index of suspicion of malignancy needs to be borne in mind in dealing with a lymph node swelling in elderly.
Volume change occurs as a result of exposure to fuel (usually swelling); and the amount of swell is a measure of the resistance of the particular elastomers to the fuel.
(5) Steady the load at the specified stress level, and observe and record the swelling deformation qualities of red mudstone.
Figure 5 shows the swelling capacity of crosslinked NaCMC-g-PAA as function of cross-linker (MBA) concentration.
In recent years, various methods, such as phase inversion [17], freeze-drying [18], water-soluble porogens [19], and foaming [20-22], have been introduced for the preparation of superabsorbent materials in order to increase the swelling rate by endowing them with a pore structure.
Post-operative complications (pain and swelling) were assessed pre operatively and then on 3rd and 7th day post operatively using visual analogue scale and objective scale for swelling measurement using five anatomical points on face.