Self-healing performance of an epoxy coating containing microencapsulated alkyd resin based on coconut oil

The microcapsules (MCs) containing alkyd resin based on coconut oil with different concentrations: 5, 10, and 15% were incorporated into a commercial epoxy coating and the coating was then applied on steel panel substrate. The effect of incorporation MCs on properties of the coatings was evaluated via assessment of surface roughness, gloss, adhesion strength, and bending elongation of the coatings containing MCs and comparing them with the properties of control coating. Furthermore, the healing performance in the epoxy coating and consequently their ability to protect the substrate against corrosion of the scratched coatings without and with MCs were also investigated in 5 wt% NaCl solution using potentiodynamic polarization tests and Electrochemical Impedance Spectroscopy (EIS). The obtained results revealed that increasing concentration of MCs in epoxy resin caused to a decrease in gloss and adhesion strength as well as a reduction in bending elongation of coatings. A good agreement between potentiodynamic polarization and EIS results indicated when the MCs concentration was equal to 10%, the amount of the released healing agent (alkyd resin based on coconut oil) was adequate to satisfactorily heal the cracks.