Fabrication of cardanol (a phenolic lipid) based polyamine coatings for anti-corrosive applications

Inhibition of corrosive ions is an important parameter for industrial steel application. The present study deals with the synthesis of polyamine (PA) resin-based coatings from cardanol (Col) with three different ratios (PA1-PA3). Fourier Transform Infra-Red (FTIR) and Nuclear Magnetic Resonance (NMR; ¹H & ¹³C) spectroscopy were used to characterize the presence of functional group and structural elucidation of resin, respectively. Physico-mechanical testing of PA coatings was performed by standard ASTM methods to check their mechanical durability. PA1 coatings seemed to have the best physico-mechanical properties and are considered to be the optimum composition for the preparation of durable coatings. Thermal analysis was performed using thermogravimetric analysis (TGA) which revealed that these coatings were stable up to 520 °C. Contact angle values (117°) suggested that these PA1 coating has self-cleaning ability and less wettability. Corrosion inhibition efficiency of these coatings was examined through electrochemical impedance spectroscopy (EIS) investigations. The superior corrosion inhibition properties of PA1 (one-component) coatings were compared with reported Col-based epoxy (two-component) coatings. Such one-component coatings can be used in place of epoxy coatings that could eliminate the usage of two-component coatings resulting in less consumption of energy, time, and material. Moreover, this work supports an approach for the synthesis of green polymeric coating using economic precursor in absence of expensive catalysts/solvents. PA coating have high efficiency towards corrosion resistance, thus, could effectively be used in the field of corrosion protection in near future.