Corn oil based poly(ether amide urethane) coating material—Synthesis, characterization and coating properties

Abstract

Polyetheramide (CPETA) resin was synthesized from N,N-bis (2-hydroxy ethyl) corn oil fatty amide (HECFA) and catechol through condensation polymerization. CPETA was further cured with isophorone diisocyanate (IPDI) in different weight percentage (20, 25, 30, 35, 40wt.%) to obtain poly(ether amide urethane) (CPETAU). The structural elucidation of HECFA, CPETA and CPETAU was carried out by FT-IR, 1H NMR and 13C NMR spectroscopic techniques. Physico-chemical and physico-mechanical properties of these resins were investigated by standard methods. Thermal behavior was assessed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The corrosion resistance performance of CPETAU coatings on mild steel strips was investigated by potentiodynamic polarization studies in different corrosive media (3.5wt.% HCl, 5.0wt.% NaCl, tap water) at room temperature. Amongst all the compositions, CPETAU coatings showed good scratch hardness (2.20kg), impact resistance (150lb/inch), gloss with corrosion rate obtained as 1.377×10−2 (mm/year) and 2.359×10−3 (mm/year) in 3.5wt.% HCl and 5.0wt.% NaCl solution, respectively. CPETAU coatings can be safely used up to 250°C.