THE RELATIONSHIP BETWEEN ADHESION AND FRICTION

Adhesion and friction experiments were carried on a variety of differe nt surfaces, both lubricated and unlubricated, using the Surface Force s Apparatus technique. The surfaces were mica, silica, alumina, and a variety of surfactant-coated surfaces, and measurements were made at d ifferent temperatures, relative humidities, applied loads, loading and unloading rates, sliding speeds and previous histories. The aim was t o investigate the fundamental correlations between friction and adhesi on forces using fairly ideal surfaces under conditions where little or no damage occurs. We find that - in spite of the great complexity and dependence on many parameters - the measured friction and time-depend ent adhesion forces are correlated. These correlations can be understo od in terms of simple models, expressed with simple equations, and rep resented graphically by dynamic or friction ''phase diagrams''. The co rrelations we have observed should apply tn other energy dissipating s ystems. and it is proposed that a general theoretical framework - simi lar to the WLF Equation commonly used to describe the viscoelastic ene rgy losses in bulk polymer systems - can be developed for predicting t he energy dissipation of dynamic systems tinder different conditions.