Preparation and characterization of alkyd coating with self-healing ability / Nornadila Mohd Saman

Apart from decorative purposes, coatings have also been applied to metal surface to inhibit corrosion by protecting the substrate from environmental exposure. This work focuses on the use of UV-curable palm oil-based alkyd for surface coating application. This type of coating is a form of environmentally friendly coating that involves low, if any, emission of volatile organic compounds (VOCs) during curing. Nonetheless, UV-cured alkyd coating is just similar to any other coatings, where it is vulnerable to damages such as formation of microcracks during its service. By introducing self-healing properties into the alkyd coating, it can avoid further catastrophic failure and prolong the lifespan of the coating and its substrate. One of the objectives of this study is to introduce self-healing ability to the alkyd coating. Self-healing alkyd coating consists of microcapsules containing healing agent, implanted into alkyd coating matrix. Alkyd was synthesized as a binder in this coating mixture while methyl methacrylate (MMA) serves as reactive diluents and benzophenone as UV-photoinitiator. Diglycidyl ether bisphenol-A based epoxy (EPON828) and pentaerythritol tetrakis (3-mercaptopropionate) (PETMP) were chosen as the healing agents and microencapsulated by in situ polymerization. Self-healing process of the coating took 10 minutes after the coating was intentionally scratched. The efficacy of the self-healing ability of the coating was investigated using high powered microscope and potentiodynamic polarization. The coating showed excellent corrosion resistance and recorded good film properties

Acrylated Epoxidized Soybean Oil as a Green Alternative Healant in Development of Autonomous Self-Healing Materials

Progresses in the development of self-healing materials have resulted in transition from repairing damaged materials via external interference to autonomous internal healing process. This paper explores reaction between acrylated expoxidized soybean oil (AESO) with pentaerythritol tetrakis(3-mercaptopropionate) (PETMP) hardener, followed by microencapsulation of AESO for its potential use in a novel self-healing system. Self-healing reaction involving AESO and PETMP is considered more environmentally friendly than most of the reported self-healing reactions not only because AESO is derived from renewable resources, but also due to the fact that the reaction does not rely on any heavy metal catalyst. Such catalysts are usually introduced in a self-healing system to speed up the intended healing process and it could be very harmful to the environment and also to the end users. It was found that AESO and PETMP are able to crosslink with each other and solidify at room temperature within 15 min of mixing. The reaction occurs readily at room temperature without any external interference, suggesting the viability of the reaction to be utilized in an autonomous self-healing system. This paper follows through with microencapsulation of AESO in melamine-urea-formaldehyde, and result of the characterizations reveal that the microcapsules obtained are spherical with average diameter of around 150 µm, free-flowing, thermally stable at temperature up to 200 °C, and the calculated % of microencapsulation reached as high as 86.4%. © 2018, Springer Science+Business Media, LLC, part of Springer Nature