Blistering of Glass-Epoxy Amine Adhesive Joints in Water Vapour at High Pressure. An Indication of Interfacial Crumpling

When joints are made between solids, the surfaces of which are soluble in water, with an epoxy-amine adhesive, blistering is observed in water vapour at high temperature and pressure. The occurrence of these blisters follows the cavitation theory in elastomers. Microscopic observation of the blisters suggest that they come from initial smaller ones which are homogeneously spread along the interface (not air bubbles or defects) and grow under the osmotic pressure developed by water condensation in the initial “sucker” and by surface dissolution. These observations led us to suggest that the solid/adhesive interface crumples during hardening of the adhesive and that many small suckers exist along the interface. This leads to a new model for the loss of adherence of epoxy-metal joints kept in high humidities.