Self-healable bio-based epoxy resin from epoxidized palm oil

Abstract

Epoxy resin is a thermoset with superior mechanical strength, thermal stability and dimensional stability, granted by the permanent crosslinking networks in the epoxy network. Despite its advantages, the rigid 3D epoxy resin precludes flow, resulting in the recycling and reprocessing of epoxy resin becomes impossible. The incorporation of covalent adaptable network (CAN) into the epoxy resin enable their network topology to be rearranged and permits recycling of epoxy resin. This project highlights the self-healing efficiency as well as mechanical and thermal properties of epoxy resin synthesized from various stoichiometric ratios (R) of curing agent (citric acid monohydrate) to epoxidized palm oil (EPO). EPO was cross-linked with citric acid monohydrate (CA) without the usage of a catalyst under specific curing condition to produce self-healable epoxy resin. Fourier - Transformed Infrared Spectroscopy (FTIR) analysis shows that the epoxide group in EPO successfully reacted with carboxylic groups in (CA) via ring-opening reaction to form ß - hydroxyester networks. Thermogravimetric Analysis (TGA) analysis reveals the thermal stability of each formulation, indicating that R 0.5 possess the highest crystallinity and R 1.5 has the highest Tg (8.09 °C) among the others. Interestingly, R 1.0 which is the lowest in terms of thermal stability exhibited the best self-healing performance. To further improve the overall properties of the synthesized epoxy thermoset, reinforcement materials need to be added during the synthesis process.