EXPERIMENTAL-STUDY ON AN EPOXY GLUE PLUS ALUMINUM MODEL INTERFACE

Although bonding of aluminium sections by epoxy resins is of widespread use, in particular in the aerospace industry, the chemical interactions which are involved at the interface of such systems are not clearly understood. This is mainly due to the complexity of the industrial materials together with the difficulty of characterizing a buried interface at a molecular scale. Hence amine alcohols provide useful simple models for amine-cured epoxy resins, which can be deposited in ultrathin 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 electron spectroscopy (AES) and high-resolution electron energy loss spectroscopy (HREELS). We have shown that: i) on hydroxylated aluminium, interaction occurs through elimination of a water molecule between the 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 the amine termination of the monoethanolamine on the aluminium sites. These results are. interpreted in the frame of electron donor/acceptor theory.