New perspectives in polymer adhesion mechanisms--importance of diffusion and molecular bonding in adhesion

摘要

Abstract: This paper reviews new perspectives in polymer adhesion mechanisms. Both reptation theory and related experiments have demonstrated the existence of either self-diffusion or interdiffusion of rubbery polymers at the interfaces. Thus, adhesive strength, green strength, and tack of elastomeric adhesives can be at least partially explained on the basis of the diffusion mechanism. Besides diffusion, the adsorption mechanism plays a major role in achieving molecular contact. Without molecular contact, polymer molecules can not attain adequate diffusion or physical adsorption at the interface through van der Waals attraction. When the molecular distance is less than 4 angstroms, chemisorption can take place due to molecular interaction. Thus, both physisorption and chemisorption are important in enhancing adhesion. In addition to the above mechanisms, we shall mention briefly the mechanisms of mechanical interlocking, chemical bonding, and electronic adhesion.!86