R.E HAMADE* Department of Mechanical Engineering, American University of Beirut (AUB), P.O. Box 11-0236, RiadEl-Solh, Beirut 11072020, Lebanon

Abstract-The beneficial effect of y-aminopropyltriethoxysilane (y-APS) coupling agent on the durability of adhesive bonds under cathodic conditions is investigated. To improve the durability of commercially available primer/adhesive systems commonly used in rubber-to-metal joints, the silane is incorporated into the primer component. Mass uptake tests on thin free-standing films in highly alkaline NaOH solutions show that the primer re-formulation resulted in enhanced hydrolysis resistance of the primer itself. The mass uptake following exposure to alkali is found to be inversely proportional to silane concentration. Similarly, chemical degradation rate of the primer film is found to decrease with increasing y-APS concentration. Also, joints (Strip Blister Specimens, SBS) utilizing mild steel substrates bonded with the J/-APS silane-modified primer were found to be more resistant to delamination as compared with the control primer/adhesive system under the same test conditions. The concentration of the silane is correlated with the reduction of delamination rates in both 1 M NaOH and artificial seawater.