Adhesion

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adhesion

1. an attraction or repulsion between the molecules of unlike substances in contact: distinguished from cohesion
2. Pathol abnormal union of structures or parts
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

Adhesion

The property of a material that allows it to bond to the surface to which it is applied.
Illustrated Dictionary of Architecture Copyright © 2012, 2002, 1998 by The McGraw-Hill Companies, Inc. All rights reserved
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Adhesion

 

the attachment of surfaces of two unlike solids or liquids to each other. An example of adhesion is the attachment of water drops to glass. Adhesion and absorption have the same causes. In quantitative terms, adhesion is characterized by the specific work done in separating the adhering bodies. This work is calculated per unit area of the surfaces in contact, and it depends on the way in which the separation is carried out: by shear along the interface or by peeling off in a direction perpendicular to the surface. Adhesion is sometimes greater than cohesion, which characterizes the cohesive forces joining particles within a body. In that case the reparation of the two bodies results in the rupture of the weaker one.

Adhesion between solids with uneven surfaces is usually not great, since they are actually in contact only over isolated protruding areas of their surfaces. Adhesion of a liquid and a solid or of two immiscible liquids may attain maximum values because of the complete contact over the entire contact area. When a solid is coated by a liquid polymer, the polymer penetrates into recesses and pores in the solid. After the polymer has cured, a bonding sometimes known as mechanical adhesion takes place. In that case the cohesion in the cured polymer must be overcome in order to peel off the polymeric film. In order to achieve the maximum adhesion, solids are joined in a plastic or elastic state under pressure—for example, with rubber cement or in cold welding of metals. Firm adhesion is also achieved when a new solid phase forms on the interface—for example, in electroplating or in the case of surface-active chemical compounds (oxide films, sulfide films, and so forth).

Adhesion of polymers is favored when the macromolecules are polar molecules having a large number of chemically active functional groups. Active additives whose molecules make a firm bond with the film on one end and a firm bond with the substrate on the other end, thereby forming an oriented absorptive layer, are introduced into the composition of an adhesive or of a film-forming polymer in order to improve adhesion. Autoadhesion may occur when two volumes of the same polymer come into contact, when the fusion of macromolecules or portions of the polymer occur from one volume into the other. The strength of this bond increases with time, tending toward a limit known as cohesive strength. The phenomenon of adhesion occurs in welding, soldering, tin-plating, adhesive bonding, fabrication of photographic materials, and application of polymeric paints, coats, and varnishes to protect metal parts from corrosion. The reasons for failure of the adhesive joint in the last case are the stresses generated through shrinkage of the film and the difference between the thermal expansion coefficients of the film and the metal.

Adhesion is not only a precondition for the formation of a high-quality coating bonding a welded or adhesive joint; it is also responsible for the enhanced wear on rubbing parts. A layer of lubricant is introduced to hinder contact between the surfaces and thereby eliminate adhesion.

REFERENCES

Krotova, N. A. O skleivanii i prilipanii. Moscow, 1956.
Voiutskii, S. S. Autogeziia i adgeziia vysokopolimerov. Moscow, 1960.
Deriagin, B. V., and N. A. Krotova. Adgeziia. Moscow-Leningrad, 1949.

V. I. SHIMULIS


Adhesion

 

a fibrous structure by which organs of the serous and synovial cavities adhere. Adhesions usually develop as a result of inflammatory processes. A body part, for example, a lung, the heart, or a joint, may become limited in its mobility and dysfunctional. Adhesions in the abdominal cavity can lead to the development of intestinal obstruction. They are often accompanied by pain. Adhesions are treated with physical therapy and sometimes surgery.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

adhesion

[ad′hē·zhən]
(botany)
Growing together of members of different and distinct whorls.
(electromagnetism)
Any mutually attractive force holding together two magnetic bodies, or two oppositely charged nonconducting bodies.
(engineering)
Intimate sticking together of metal surfaces under compressive stresses by formation of metallic bonds.
(mechanics)
The force of static friction between two bodies, or the effects of this force.
(medicine)
The abnormal union of an organ or part with some other part by formation of fibrous tissue.
(physics)
The tendency, due to intermolecular forces, for matter to cling to other matter.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

adhesion

1. The joining of two surfaces as pieces of wood, metal, plastic, or other construction materials, by means of a viscous, sticky composition such as cement or glue.
2. The sticking together of two surfaces by means of physical and chemical forces such as those which bind a paint film to a surface.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
Li, "Comparison of abdominal adhesion after modified and Stark's section," Chinese Journal of Postgraduate Medicine, vol.
The process of peritoneal healing plays an important role in postoperative abdominal adhesion formation.
Grade Criteria 0 No adhesion band is present 1 A single adhesion band forms between the viscera or between a viscus and the abdominal wall 2 Two bands form between the viscera or between the viscera and abdominal wall 3 More than two bands form between the viscera or between the viscera and abdominal wall, or the whole intestine forms a mass without adhering to the abdominal wall 4 The viscera have directly adhered to the abdominal wall, irrespective of the number of bands Table 4: Effect of IFRD on rat abdominal adhesions after operation.
Panitch, "Abdominal adhesions: current and novel therapies," Journal of Surgical Research, vol.
Further studies with larger sample sizes combining various skin and scar properties may be helpful for prediction of postoperative intra abdominal adhesions.
Bonjer, "Abdominal adhesions: intestinal obstruction, pain, and infertility," Surgical Endoscopy, vol.
Prospective controlled randomized trial on prevention of postoperative abdominal adhesions by Icodextrin 4% solution after laparotomic operation for small bowel obstruction caused by adherences [POPA study: Prevention of Postoperative Adhesions on behalf of the World Society of Emergency Surgery].
Intra-operative findings included dense intra abdominal adhesions and multiple sigmoid diverticula.
Morbid obesity and the risk of significant abdominal adhesions should be viewed with caution, according to Dr.
The biggest risk factor for laparoscopy-related intestinal injury is the presence of pelvic or abdominal adhesions. (1,2) Adhesions inevitably form after any intraabdominal surgery, and new adhesions are likely with each successive intra-abdominal procedure.
Several studies have assessed the rate of abdominal adhesions in patients who have had previous surgery.
Laparoscopic cholecystectomy was started by releasing and dividing extensive multiple abdominal adhesions, both liver lobes were pulled up to the anterior abdominal wall, and the gallbladder was grossly distended and very large in size and was retracted above the surface of the liver.