An interaction study of epoxy varnishes with different metal oxides
Sprache des Vortragstitels:
The Advanced Materials & Surfaces International Conference GAMS 2022
Sprache des Tagungstitel:
Bonding of metal surfaces with adhesives is dependent on base-acid interactions between the coating and the metal surface. The chemical structure and morphology of the metal oxide passivation layer has an important impact on these interactions. Hence, sheets of pure Zn, Sn and Al were investigated in the uncoated reference state and characterized by X-ray photoelectron spectroscopy (XPS). Furthermore, components of the water-borne model epoxy varnish and the epoxy coating on the metal substrates were also analysed by XPS.
To model a possible reaction between the used hardener dicyandiamide (DICY) and the metal oxides, the substrates were immersed in a solution of DICY in pure water. By XPS analysis chemical reactions of the amine groups of DICY with the metal oxides were ascertained. Performing cryo ultra-low-angle microtomy (cryo-ULAM), a preparation technique which has proven to be successful for depth profiling of polymeric samples without destroying the chemistry, it was confirmed that a similar reaction occurs even in the more complex system of the model epoxy coating and the metal oxide passivation layer. Moreover, an enrichment of DICY hardener at the metal/polymer interface was detected for Zn and Sn substrates.