To function optimally, an adhesive should have good adhesion, or physical (and sometimes chemical) bonding of one material to another because of a variety of possible molecular interactions between the substrate surface and the adhesive. It should also have good cohesion, or internal strength, as a result of a variety of molecular forces within the adhesive itself, including chemical bonds, entanglements due to high molecular weight, intermolecular interactions, and mechanical adhesion.
Although the characteristics of a tape’s adhesive can be formulated to activate upon exposure to heat or solvent, most often their needed catalyst is just pressure. Customarily, firm and even pressure during application increases bond strength. From this point, the ultimate bond strength may take between a few minutes and 72 hours to be reached. Most often, however, bonded parts can be handled immediately.
Materials and surface conditions
Stresses on the substrate and bond