Contact adhesion of rubber against glass

An estimate of the surface energy of solids can be obtained by wetting measurements. An alternative, in the case of rubber, is to deduce the surface energy by direct optical observations of solid-solid contact area.This study reports contact observations for the adhesion of rubber hemispheres against glass coverslips. In particular, the effect of ambient relative humidity has been examined. Results show that with increasing humidity the level of peel energy (separating surfaces) decreases, but the contact surface energy (joining surfaces) increases. Measurements suggest this is due to the capillary action of adsorbed water films