Fire-Safe Fully Bio-Based Schiff Base Epoxy Thermosets with Excellent Mechanical Properties and Adjustable Degradability

Currently, because of the depletion of petroleum resources and pollution problems associated with the use of petrochemicals, bio-based epoxy thermosets have received wide attention. However, epoxy thermosets derived entirely from bio-based raw materials combining high performances in mechanical properties, fire resistance, and degradation are less reported. In this work, a fully bio-based Schiff base epoxy resin named VA-FA-EP is prepared from vanillin (VA) and 2-furfurylamine (FA). The curing kinetics and behavior of the imine exchange reaction are explored systematically. After being cured by 4,4′-diaminodiphenylmethane (DDM), VA-FA-EP/DDM exhibits excellent mechanical properties with a glass transition temperature of 200.1 °C. VA-FA-EP/DDM has also been proven to have good fire resistance. There are significant reductions of 66.73% and 81.72% in total heat release (THR) and total smoke production (TSP), respectively. The intrinsic flame-retardant mechanism is systematically illustrated. In addition, the VA-FA-EP/DDM has also shown a good degradation property. In summary, this study offers a viable approach for producing eco-friendly fire-safe Schiff base epoxy thermosets utilizing entirely sustainable raw materials.