DURABILITY IN HIGH HUMIDITY OF GLASS-TO-LEAD ALLOY JOINTS BONDED WITHAN EPOXIDE ADHESIVE

Adhesive joints consisting of glass bonded to lead alloy with an epoxi de adhesive have been aged at 5-degrees-C at relative humidities of 50 and 100% for up to 3 months. In some joints the glass had been pretre ated with a silane coupling agent. Joints aged at 50% relative humidit y show no weakening, and at 100% joints with silane pretreatment are n ot weakened as much as those without it; many of the latter samples fe ll apart during ageing. The diffusion coefficient of water in the adhe sive has been obtained from an absorption experiment. The rate at whic h joints are weakened is higher than can be accounted for by diffusion of water in the adhesive. Water is supplied to intact regions of the adhesive bond by way of zones that have been disbonded.