The effect of moisture and temperature on the properties of an epoxide-polyamide adhesive in relation to its performance in single lap joints

A template cutting technique has been used to prepare dumb-bell shaped specimens of the epoxide-polyamide adhesive FM 1000, and their mechanical properties have been examined as a function of water exposure, testing speed, and temperature. The glass transition temperature of the wet adhesive has also been examined. Strengths of single lap joints bonded with the adhesive have been measured after exposure to warm moist air for up to 2500 hours. Strengths of wet and dry joints have been compared over a wide temperature range. The results show that the weakening effect which water has is due to plasticization of the adhesive, and that the rate of weakening depends on water diffusion within the adhesive layer.