New approach for simultaneous enhancement of anticorrosive and mechanical properties of coatings: Application of water repellent nano CaCO3-PANI emulsion nanocomposite in alkyd resin

New alkyd coatings were prepared by addition of water-based polyaniline-4% CaCO3 (PAC) nanocomposites into alkyd resin. Pure polyaniline (PANI) and PAC were synthesized using ultrasound assisted emulsion polymerization and added to alkyd resin to form nanocomposite coating. Nano CaCO3 was added in different percentage ranging from 0% to 8% of monomer during the synthesis of polyaniline. XRD and TEM reveals that water repellent nano CaCO3 is thoroughly dispersed in PANI matrix. The effect of PANI and PAC nanocomposite on mechanical and anticorrosion performance of alkyd coating was evaluated. An electrochemical measurement (Tafel Plots) shows that corrosion current I-corr was decreased from 0.89 to 0.03 mu A/cm(2), when PAC nanocomposite was added to neat coatings. Positive shift of E-corr. also indicates that PAC nanocomposite acts as an anticorrosive additive to alkyd coating. Presence of water repellant nano CaCO3 in PAC nanocomposite has exhibited dual effect, such as improvement in mechanical and anticorrosion properties. The experimental results have shown superiority of PAC nanocomposite over PANI when PAC nanocomposite added to alkyd coatings. (C) 2009 Elsevier B. V. All rights reserved.