Interface analysis of epoxy varnishes on different metal oxides by cryo-ULAM and XPS

Description

Bonding of metal surfaces with adhesives is dependent on base-acid interactions. Consequently, the chemical structure of the metal oxide has a significant impact in adhesion. For that reason, we analysed the surfaces of pure Zn, Sn and Al sheets by X-ray photoelectron spectroscopy (XPS). The metals were coated with epoxy model varnishes obtaining a coating thickness of 5 µm. The components of the water-based varnish and the cross-linked coating were also characterized by XPS. To model a possible reaction of the hardener based on dicyandiamide (DICY) and the metal oxide, the metal substrates were immersed in a solution of DICY in distilled water. The XPS investigations confirmed the hypothesized reactions of amine groups from DICY with the metal oxides. By means of 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 [1], a similar reaction was ascertained between the more complex model epoxy coatings and the metal oxide passivation layers. A pronounced enrichment of the hardener at the exposed metal/polymer interface in case of Zn and Sn was deduced.

Period	01 Jun 2022
Event title	European Conference on Applications of Surface and Interface Analysis (ECASIA 2022)
Event type	Conference
Location	Limerick, IrelandShow on map