Mechanisms of criticality in environmental adhesion loss.

Moisture attack on adhesive joints is a long-standing scientific and engineering problem. A particularly interesting observation is that when the moisture level in certain systems exceeds a critical concentration, the bonded joint shows a dramatic loss of strength. The joint interface plays a dominant role in this phenomenon; however, why a critical concentration of moisture exists and what role is played by the properties of the bulk adhesive have not been adequately addressed.

On the origins of sudden adhesion loss at a critical relative humidity: examination of bulk and interfacial contributions.

The origins for abrupt adhesion loss at a critical relative humidity (RH) for polymeric adhesives bonded to inorganic surfaces have been explored using a model poly(methyl methacrylate) (PMMA) film on glass. The interfacial and bulk water concentrations within the polymer film as a function of D 2O partial pressure were quantified using neutron reflectivity. Adhesion strength of these PMMA/SiO 2 interfaces under the same conditions was quantified using a shaft loaded blister test.