No abstract

In this study, ethyl cellulose (EC) micro and nanocapsules containing linseed oil for use in selfhealing coatings have been prepared by an emulsion-solvent evaporation method. The prepared micro and nanocapsules were individually embedded into the polyurethane coatings and the coatings were then applied on mild steel substrates using spray method. The corrosion resistance of the coatings was evaluated using linear polarisation and electrochemical impedance spectroscopy tests. Results obtained revealed that using EC nanocapsules compared to microcapsules significantly increased the corrosion resistance of the self-healing coating. In addition, the healing properties of the prepared nanocapsules containing coating would be greater than the microcapsules one.

The effect of ethyl cellulose (EC) micro/nanocapsules containing linseed oil (LO) on the cathodic disbonding of self-healing composite coatings is investigated by cathodic disbonding test and electrochemical impedance spectroscopy (EIS). Results reveal that the presence of EC nanocapsules significantly improves the cathodic disbonding resistance of the coatings so that the rates of disbonded area under the simulated condition of cathodic protection decrease from 3.882 mm 2 h for the blank coating to 0.025 mm 2 h for the nanocapsules containing coating. It may be ascribed to the releasing LO and filling the defects at the coating/substrate interface by oxidative polymerisation mechanism. EIS test results indicate that the corrosion resistance of the coatings is improved in the presence of EC nanocapsules. In addition, the coating resistance to cathodic disbonding and corrosion increase by decreasing capsule sizes. Finally, a proposed mechanism of ion diffusion through the self-healing coating's defect is schematically illustrated.