Jump to a letter: A — B — C — D — E — F — G — H — I — J — L — M — N — P — R — S — T — V — W — Y

F

Failure, adherend

joint failure by cohesive failure of the adherend.

Failure, adhesive

rupture of an adhesive bond, such that the separation appears to be at the adhesive-adherend interface. Note: Sometimes termed failure in adhesion.

Failure, cohesive

rupture of an adhesive bond, such that the separation appears to be within the adhesive.

Failure, contact

the failure of an adhesive joint as a result of incomplete contact during assembly, between adherend and adhesive surfaces or between adhesive surfaces.

Filler

a relatively nonadhesive substance added to an adhesive to improve its working properties, permanence, strength, or other qualities.

Flow

movement of an adhesive during the bonding process, before the adhesive is set.

G

Gel

a semisolid system consisting of a network of solid aggregates in which liquid is held.

Glue, n

originally, a hard gelatin obtained from hides, tendons, cartilage, bones, etc. of animals. Also, an adhesive prepared from this substance by heating with water. Through general use the term is synonymous with the term adhesive.

Glue line (bond line)

the layer of adhesive, which attaches two adherends.

Green strength

the ability of an adhesive to hold two surfaces together when brought into contact and before the adhesive develops its ultimate bond properties when fully cured.

Gum

any class of colloidal substances exuded by or prepared from plants, sticky when moist, composed of complex carbohydrates and organic acids, which are soluble or swell in water. Note: The term gum is sometimes used loosely to denote various materials that exhibit gummy characteristics under certain conditions, for example, gum balata, gum benzoin, and gum asphaltum.

H

Hardener

a substance or mixture of substances added to an adhesive to promote or control the curing reaction by taking part in it. The term is also used to designate a substance added to control the degree of hardness of the cured film.

Heat reactivation

the used of heat to effect adhesive activity, e.g., hot melt adhesive; completion of the curing process of a B-staged resin.

Honey comb core

a sheet of material, which may be metal, formed into cells (usually hexagonal) and used for sandwich construction in structural assemblies, especially in aircraft construction.

Hydrolysis

decomposition of a substrate or adhesive by a reaction with water.

I

Inhibitor

a substance that slows down a chemical reaction. Inhibitors are sometimes used in certain types of adhesives to prolong storage or working life.

Interface

the contact area between adherend and adhesive surfaces.

J

Jig

an apparatus used to hold a bonded assembly until the adhesive has cured.

Joint

the location at which two adherends are held together with a layer of adhesive.

Joint, lap

a joint made by placing one adherend partly over another and bonding together the overlapped portions.

Joint, scarf

a joint made by cutting away similar angular segments of two adherends and bonding the adherends with the cut areas fitted together.

Joint, starved

a joint that has an insufficient amount of adhesive to produce a satisfactory bond. Note: This condition may result from too thin a spread to fill the gap between the adherend, excessive penetration of the adhesive into the adherend, too short an assembly time, or the use of excessive pressure.

The following sources were used in compiling this Glossary:

• ASTM D 907, "Standard Definitions of Terms Relating to Adhesives," American Society for Testing and Materials, Conshohocken, PA.
• ASTM C717, "Terminology of Building Seals and Sealants," American Society for Testing and Materials, Conshohocken, PA.
• MIL-HDBK-691B, Military Standardization Handbook, Adhesive Bonding, Department of Defense, Washington, DC.
• Panek, J.R. and Cook, J.P., Construction Sealants and Adhesives, John Wiley & Sons, New York, 1991.
• Sharpe, L.H., "Fundamentals of Adhesives and Sealants Technology," Adhesives and Sealants, vol. 3, Engineered Materials Handbook Series, ASM International, 1990.