Synthesis and characterization of high thermally stable poly(Schiff) epoxy coatings

Epoxy resins were prepared from Schiff base monomer and polymer through two steps. The first step is based on reaction of salicyladehyde or 5,5−-methylene-bis-salicylaldehyde with o-phenylene diamine. The second step includes the reaction between Schiff base monomer or polymer with epichlorohydrine (EC) to produce epoxy resins. The chemical structures of both Schiff base monomers and polymers were determined by elemental analysis, IR and 1HNMR spectral analyses. The molecular weights of the produced epoxy resins were determined by GPC technique. The chemical structures and epoxy functionality were determined by 1HNMR analysis. The prepared epoxy resins were cured with diamine based on pentaethylene hexamine (PEHA) and p-phenylene diamine (PDA). The thermal stability of the cured resins was evaluated by DSC and TGA analysis. Thermal stability data indicate that the cured epoxy resins with aromatic amine possess higher thermal stability than that cured with aliphatic amine. The cured epoxy–amine systems were evaluated in coating applications of steel by measuring the mechanical properties and chemical resistance of the cured films.