Epoxy–amine/metal interphases: Influences from sharp needle-like crystal formation

When epoxy–amine liquid mixtures are applied onto metallic oxide layer, concomitant amine chemical sorption and metallic surface dissolution appear leading to the organo-metallic complex formation. We studied the interphase formation and used two different amines as hardener (isophoronediamine (IPDA) and diethylenetriamine (DETA)). If the complex concentration within the liquid amine or epoxy–amine prepolymer is higher than its solubility limit, complexes crystallize. Sharp needle-like crystals are observed only with modified IPDA. For Al-IPDA crystals, the melting point is about 78°C, but as the network is formed at this temperature, crystals remain present at the end of the polymerization cycle

Is gold always chemically passive? Study and comparison of the epoxy-amine/metals interphases

International audienceWhen epoxy-amine liquid mixtures are applied onto metallic substrates (such as Al, Ti, Sn, Zn, Fe, Cr, Cu, Ag, Ni, and Au), concomitant amine chemisorption and metallic surface dissolution occur, leading to organo-metallic complex formation. The interphase formation was studied, using two different amines as hardener (IsoPhoroneDiAmine and EthyleneTriAmine). If the complex concentration within the liquid amine or epoxyamine prepolymer was higher than its solubility limit, the complexes will crystallize. Sharp needle-like crystals were only observed with metal-IPDA organo-metallic complexes. A lot of metals are widely used as reactive substrates with gold as a reference, which is considered chemically inert. It is misleading, since it will be shown in this article that gold reacts with amine, just as the other metals

Properties of the interphase epoxy-amine/metal: influences from the nature of the amine and the metal

Epoxy-amine systems are used as adhesives and paints in many industrial applications. When they were applied on metallic substrates and cured, an interphase was created between the substrate and the polymer. The interphase had chemical, physical and mechanical properties, different than the bulk phase. Amines are known to chemically react with metallic ions to form organometallic complexes. Two amines were used: the diethylenetriamine (DETA) and the isophorone diamine (IPDA). When the IPDA organometallic complexes were over the solubility limit, chelates crystallized, whereas for DETA, organometallic complexes were formed but never crystallized. The crystals were analysed. For Al-IPDA crystals, the melting point was in the range of 75-80°C. The new mechanical properties came from the crystals, that remained enclosed within the vitrified polymer; this was due to the crystals melting point, which was higher than the DGEBA-IPDA systems vitrification temperature