Synthesis, characterization and the effect of the s-triazine ring on physico-mechanical and electrochemical corrosion resistance performance of waterborne castor oil alkyd

The sustainable resource based volatile organic content (VOC) free coatings with superior anticorrosive properties are some of the most in demand in the surface coating industry. In the present investigation, we report the synthesis of butylated melamine formaldehyde (BMF) cured waterborne castor alkyd (WCA-BMF) using environmentally friendly solvent for anticorrosion applications. The cured resin was characterized by spectroscopic techniques, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The molecular weight of the resin was determined by gel permeation chromatography (GPC). The corrosion protection performance of the coatings on carbon steel strips (CS) was investigated by potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and the salt spray test. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) examinations were carried out to study the morphology of bare CS and coated CS before and after exposure to a salt spray chamber. The results showed the prominent role played by the amount of BMF in the performance of the castor alkyd, as reflected by the high thermal stability, good adhesion, bending ability (1/8 inch bend test), impact resistance (>100 cm), scratch hardness (7.50 kg), along with good hydrophobicity and high corrosion protection performance. Thus, this study revealed that the presence of the s-triazine moiety in waterborne castor alkyd can produce a high performance corrosion protection coating material via a green route.