Influence of the molecular structure on the chemical resistivity and thermal stability of cured Schiff base epoxy resins

Epoxy binders were prepared from Schiff base monomers through two steps. The first step is based on condensation of hydroxy benzaldehyde derivatives with o- and p-phenylenediamine. The second step includes the reaction between Schiff base monomers with epichlorohydrin (EC) to produce epoxy binder. The synthesized epoxy binders were characterized by determination of epoxy contents and epoxy functionalities. The chemical structures and epoxy functionalities were determined by H-1 NMR analysis. The thermal stability and characteristics of the prepared Schiff base monomers and polymers as well as their epoxy resins were measured and evaluated by DSC and TGA analysis. The prepared epoxy resins were cured with polyamine. In this respect, pentaethylenehexamine (PEHA) and p-phenylenediamine (PDA) were used as aliphatic and aromatic amine, respectively. Thermal stability data indicate that epoxy resins cured with aromatic amine possess higher thermal stability than that cured with aliphatic amine. The cured epoxy polyamine systems were evaluated in coating applications of steel by measuring the mechanical properties and chemical resistance of the cured films. (C) 2006 Elsevier B.V. All rights reserved.