The mechanism of adhesion has been investigated for
years; several theories have been proposed in an attempt to provide an
explanation for adhesion phenomena. However, no single theory explains adhesion
in a general, comprehensive way.
The bonding of an adhesive to an object or a surface is the sum of a number of
mechanical, physical, and chemical forces that overlap and influence one
another. As it is not possible to separate these forces from one another, we
distinguish between
mechanical interlocking , caused by the mechanical anchoring of the
adhesive in the pores and the uneven parts of the surface,
electrostatic forces, as regard to the difference in electonegativities
of adhering materials, and the other adhesion mechanisms dealing with
intermolecular and Chemical bonding forces that occur at the interfaces of
heterogeneous systems.
This chemical adhesion mechanism is explained in the case of the intermolecular
forces by the
adsorption theory, and in the case of chemical interactions by the
chemisorption theory. The processes that play a role in the bonding of
similar types of thermoplastic high-polymer materials, e.g. homogeneous
systems, can be determined with the
diffusion theory.
