Fully bio-based epoxy resin derived from vanillin with flame retardancy and degradability

There are many applications for epoxy resin as a coating material in the automotive, electronics, and aerospace industries. However, when derived from petrochemical industries, adversely affect the environment, as they are rigid and resistant to recycling due to inherent cross-linked structure. In the present study, we prepared green epoxy resin from renewable resources, able to replace the conventionally produced DGEBA thermoset. Initially, we synthesized an epoxy thermoset from vanillin-derived Schiff base epoxy monomer (VTA-EP) that was thermally cured with bio-based 5, 5′-methylenedifurfurylamine (DFA). Due to the unsaturated double bond in cured VTA-EP/DFA thermoset displayed a relatively high glass transition temperature (Tg ~ 170 °C) than the DGEBA/DDM system. Also, tensile strength (60 MPa), storage modulus (3271 MPa), and elongation at break (2.8%) were higher. Additionally, the peak of heat release rate (PHRR) and the total heat release (THR) of the cured VTA-EP/DFA resin decreased, and LOI and UL-94 ratings were improved. The green epoxy thermoset exhibited good dissolution in various acidic conditions due to the degradability of the Schiff base network in contrast to DGEBA/DDM. This work demonstrates that the combination of biomass with Schiff base structure provides a versatile platform for the fabrication of multifunctional vanillin-derived epoxy thermosets.