2026-11-03
Technical Terminology for Adhesives
▶ Adhesion
A state in which the surfaces of two materials are held together by chemical forces, physical forces, or a combination of both.
▶ Adhesive
A substance capable of bonding materials (adherends) together through the process of adhesion.
▶ Cohesion
A state in which the particles within a single substance are held together by primary and/or secondary valence forces.
▶ Adhesive failure
A failure that is visible to the naked eye, occurring at the interface between the adhesive and the adherend.
▶ Cohesive failure
A failure that is visible to the naked eye, occurring within the body of the adhesive or the adherend.
▶ Compatibility
The ability of two or more substances to exhibit mutual affinity when mixed together.
▶ Mechanical adhesion
Bonding between the surfaces of two materials achieved through the interlocking action of an adhesive.
▶ Adherend
An object that is to be bonded (joined) using an adhesive.
▶ Substrate
A material upon the surface of which an adhesive is applied.
▶ Wetting
The affinity of a liquid for a solid surface. The smaller the contact angle between the two, the more easily the solid surface is wetted by the liquid.
▶ Drying
A process in which the amount of solvent or dispersion medium is reduced—through evaporation or absorption—thereby altering the physical state of the adhesive on the adherend.
▶ Bonding / Adhering
Joining the surfaces of substrates together using an adhesive.
▶ Curing
The process by which an adhesive acquires and enhances properties—such as bond strength—through chemical reactions (e.g., polymerization, cross-linking).
▶ Hardening
The process by which an adhesive acquires and enhances properties—such as bond strength—through chemical reactions or physical processes (e.g., polymerization, oxidation, gelation, hydration, cooling, evaporation, etc.).
▶ Cross-linking
The process of forming chemical bonds between molecules, resulting in a three-dimensional network structure.
▶ Adhesive Layer
The layer of adhesive present within a bonded assembly.
▶ Delamination
The separation of layers in a laminated product, caused by failure within the adhesive, the substrate, or at the interface between them.
▶ Adhesive Squeeze-out (Flash)
Excess adhesive that is forced out from the adhesive layer when pressure is applied to an assembly.
▶ Adhesive Fillet
Adhesive that fills the junction between two substrates (e.g., the rounded bead of adhesive formed at the ends of a honeycomb core when bonded to a facing material).
▶ Degree of Cure
A measure of the extent of the chemical reaction that has occurred during the curing of an adhesive.
▶ Aging
The phenomenon wherein the properties of a bonded assembly change over time.