INDUSTRIAL APPLICATIONS OF XPS - STUDY OF POLYMER-TO-METAL ADHESION FAILURE

XPS has been used to study the mechanism of polymer-to-metal adhesion failure. The rubber-brass interface was analyzed following standard vulcanization and various ageing treatments. Under normal conditions an interfacial film consisting of ZnO, ZnS and CuxS if formed. Thermal ageing had no effect but ageing in steam led to a considerable film growth as a result of brass dezincification and a subsequent increase of sulphidization rate. Low bond strength is the result of cohesive failure of this film (Weak Boundary Layer). Ageing in oxygen also led to a Weak Boundary Layer consisting of CuSO4 and ZnSO4. Adhesion of paint to galvanized steel does not involve chemical bonding but is of the physical type. During accelerated weathering adhesive failure occurs by formation of water-soluble zinc corrosion products at the interface. In alkyd-based paint formulations high concentrations of zinc were detected following ageing in conditions of high humidity. Adhesion failure was the result of saponification of the polymer by zinc ions leading to a Weak Boundary Layer of zinc soaps. © 1979.