Diffusion associated with interdiffusion

We examine in some detail the important diffusion coefficient, which, when viewed mathematically, is the proportionality constant in Pick s law. It is also a material property that depends on the nature of the diffusion species, the matrix through which diffusion takes place, as well as on temperature, and, in the case of gases, on pressure. We consider in some detail the diffusivities of gases within gases, within liquids, and within solids, and the diffusivities associated with the interdiffusion of liquids and solids. These coefficients are of considerable practical importance in various engineering disciplines, in materials processing, and in the biological and environmental... 

Much of Voyutskii s original work was done on the self-adhesion (called autohesion) of unvulcanized rubbers. It was subsequently extended to polymer adhesion, more generally. The theory postulates that the molecules of the two parts of the specimen interdiffuse, so that the interface becomes diffuse and eventually disappears. For polymers in contact, Voyutskii studied the effects on adhesion of such variables as time, temperature, contact pressure, molecular weight, polarity, and crosslinking. He argued that the results proved that the adhesion was associated with the interdiffusion of polymer chains. 

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