Resumen
Protective coating layer applied to materials surfaces to prevent corrosion is susceptible to mechanical damages and other degradation processes. Self-healing coating from double-walled microcapsules could prolong the service life of the coating, allowing less maintenance and reduce cost. Self-healing double-walled microcapsules with epoxy resin as the core material and poly (melamine urea formaldehyde) (PMUF) as the shell material was synthesized via in situ polymerization in an oil-in-water emulsion technique. New combination of imidazole and acetylacetonates with double walled PMUF microcapsules were introduced to address the problems of self-healing and corrosion mitigation at the same time. The produced microcapsules were confirmed by characterization using Fourier Transform Infrared Spectroscopy (FTIR). Field emission Scanning Electron Microscope (FESEM) and Optical Microscope (OM) were used to analyse the surface morphology and shell wall thickness of the microcapsules produced. The thermal properties of the coatings were analysed using Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Mechanical properties of the coatings such as flexural strength and adhesion strength were investigated using three-point bending test and pull out method. Self-Healing properties and corrosion mitigation were evaluated using Single Edge Notch Bending and weight loss corrosion test. From the surface morphology, microcapsules synthesized under 800 rpm, 2:1 core-to-shell-ratio and 2 wt% of surfactants were the best. The results showed that addition of 10 wt% of microcapsules in coatings can achieve 52.22% of self-healing performance and the coating with addition of microcapsules and hardener complexes can inhibit corrosion up to 99%.