Diffusion theory, bonding between polymer materials is due to the mutual diffusion between geothermal stop motion caused by adhesive and adherend surface molecules or segments of each other, between the adhesive and adherend interface gradually disappear, forming firmly with the intertwining of bonding strength of the joint increased with the extension of time the maximum value, if the adhesive is coated with solvent to form the adherend surface, and the adherend surface and swelled or dissolved in this solvent, then the mutual diffusion effect is more significant, the bonding strength is high, because the main factors of adhesive and adherend mutual diffusion is adhesion, the adhesive strength and their compatibility on.
The bonding between polymer materials can be divided into the same kind of polymer material and different kinds of self-adhesive polymer materials. The former is the diffusion of the same molecule, and the latter is the diffusion of different molecules. The results of the two kinds of diffusion can make the adhesive and the adhesive molecules interweave together, so as to form a solid combination.
However, the diffusion theory can not explain the bonding effect between different polymer materials, and it is almost impossible to explain the bonding between polymer and metal.