Enhancing Corrosion Resistance Property of Mild Steel by Benzoxazine Synthesized from Vanillin and Copolymerize with Urethane

Abstract

Benzoxazine monomer prepared from vanillin and n-butylamine was characterized by 1H NMR, 13C NMR, FT-IR and UV visible spectroscopic techniques. The synthesized monomer was coated on the mild steel with isocyanate hardener in varying concentrations of isocyanate of the poly(VaBz-PU) and cured. The thermal properties of the monomer with and without isocyanate hardener were studied by TGA and DSC methods. The effect of various concentrations of isocyanate (PU) hardener with benzoxazine monomer on hardness, water absorption and gel absorption was investigated. Various concentrations of PU hardener with benzoxazine coating (VaBz-PU) on the mild steel were investigated by the electrochemical impedance and polarization studies. The study revealed that an increasing concentration of isocyante in the coating with benzoxazine increased their thermal, chemical and anticorrosive properties. The DFT calculations were also performed to support the anti-corrosive ability of the material.