The mechanics of adhesion of viscoelastic solids

Abstract

Abstract The experimental study of adhesion between common solids is bedevilled by the fad that, with exception of cleaved mica, inevitable roughness of the surfaces is greater than the range of surface forces. A new situation arose with the technique of casting low-modulus rubber with an optically smooth surface. When placed in contact with each other, or with a smooth hard surface like plate glass, such specimens are sufficiently compliant to make intimate contact throughout the whole of their apparent contact area. High adhesion is then observed; in fact the measured force required to separate the surfaces is generally greatly in excess of that which would be expected from the action of surface forces alone. The measured force of adhesion is found to depend on the rate of separation and to correlate with the viscoelastic properties of the rubber. The present state of knowledge of this phenomenon is reviewed and the mechanics of the process whereby the viscoelastic properties of the solids amplify their true surface energy is explained.