EXPERIMENTAL-STUDY ON AN EPOXY GLUE PLUS ALUMINUM MODEL INTERFACE

Although bonding of aluminium sections by epoxy resins is of widesprea d use, in particular in the aerospace industry, the chemical interacti ons which are involved at the interface of such systems are not clearl y understood. This is mainly due to the complexity of the industrial m aterials together with the difficulty of characterizing a buried inter face at a molecular scale. Hence amine alcohols provide useful simple models for amine-cured epoxy resins, which can be deposited in ultrath in layers, thus allowing characterization of the interface by surface analysis techniques. Adsorption of monoethanolamine onto clean and in- situ hydroxylated aluminium (100) surfaces has been studied by Auger e lectron spectroscopy (AES) and high-resolution electron energy loss sp ectroscopy (HREELS). We have shown that: i) on hydroxylated aluminium, interaction occurs through elimination of a water molecule between th e alcohol termination of the monoethanolamine and the surface hydroxyl groups adsorbed in tetrahedral sites. A strong Al-O-C bond is formed; ii) on clean aluminium, interaction occurs through coordination of th e amine termination of the monoethanolamine on the aluminium sites. Th ese results are. interpreted in the frame of electron donor/acceptor t heory.