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Theories of Fundamental Adhesion

Abstract

The historical development and current status of the four classical theories of adhesion are first reviewed. The adsorption theory emphasizes the point that once adhesive and substrate come into contact, forces of attraction will act between them. As long as the extent of wetting is good, these forces, whether primary bonds, such as covalent, or secondary van der Waals forces, are generally considered sufficient to give a high bond strength. Primary bonding may be necessary to achieve bond durability in a hostile environment.

The mechanical theory focuses on interlocking between adhesive and a rough substrate surface. Again good wetting is required, or surface roughening is likely to lead to poor bond strength. It has been shown to apply to some surfaces rough on a macroscale as well as to microfibrous and microporous surfaces, such as anodized aluminum. The enhanced adhesion is associated with increasing plastic energy dissipation during