Self-healing epoxy coating based on tung oil-containing microcapsules for corrosion protection

• Published in: Progress in organic coatings 2021-07, Vol.156, p.106236, Article 106236
• Main Authors: Li, Jianyang, Shi, Hongwei, Liu, Fuchun, Han, En-Hou
• Format: Article
• Language: English
• Subjects: Adhesion tests; Coating effects; Corrosion prevention; Corrosion protection; EIS; Electrochemical impedance spectroscopy; Epoxy coatings; Microcapsules; Polymerization; Salt spray tests; Self healing materials; Self-healing; Substrates
• ISSN: 0300-9440; 1873-331X
• DOI: 10.1016/j.porgcoat.2021.106236

•Microcapsules with a mean diameter of 8.5 μm were synthesized.•The adhesion and corrosion resistance of microcapsules-containing epoxy coatings were studied.•The resistance of new film cause by leakage of tung oil is approximately 106 Ω cm2. In this work, urea-formaldehyde (UF) microcapsules loaded with tung oil were prepared by in-situ polymerization. The mean diameter of the obtained microcapsules was 8.5 μm. The self-healing coating was prepared by the addition of 5 wt.% microcapsules into an epoxy matrix and then painted on the AA2024 substrate. The effect on the coating properties after the incorporation of microcapsules was investigated by adhesion tests and electrochemical impedance spectroscopy (EIS). It is found that 5 wt.% microcapsules in coating formulations did not impart a significant negative effect on coating properties. SEM and EIS tests were used to evaluate the self-healing effect. According to the fitting results of the EIS data on the scratched samples, the new film that formed by the polymerization of tung oil at the scratched area in the self-healing coating displays a resistance value of more than 106 Ω·cm2, which is much higher than 103 Ω·cm2 of the oxide layer in the neat epoxy coating. The neutral salt spray tests also confirm the good anti-corrosion performance of the self-healing coating.