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.