Chemical and electrochemical corrosion studies of ricinus communis oil based poly(urethane-ricinoleamide) coatings

Abstract

In view of the depletion and possible exhaust of fossil fuels in near future, enormous increase in the cost of petroleum products and production of volatile organic compounds (VOC) by synthetic polymers and their application, the proposed article reports the development of sustainable resource based high performance Ricinus communis oil (Castor Oil) [RC] poly(urethane-ricinoleamide) [PUR] corrosion resistant coatings on mild steel. The physico-mechanical properties were investigated using standard methods. The corrosion resistance performance of PUR coatings was evaluated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in acid (3.5 wt% HCl) and alkaline (3.5 wt% NaOH) mediums. The weight loss measurement was also carried out under tap water (Cl- ion 63 mg/l; Conductivity 0.953 mS/A). Salt mist test (5 wt% NaCl) was performed on these coatings. The effect of additional -OH functionality of RC oil on the corrosion resistance performance of PUR coatings was also discussed. These investigations reveal that the PUR coatings provide protection to the mild steel by reducing the corrosion current density by 104 times as compare to bare MS. These coatings also exhibits higher corrosion resistance performance as compared to other reported sustainable resource based coating systems, hence show good potential for their commercial application.