A bio-based epoxy resin derived from syringaldehyde with excellent mechanical properties, flame retardant and high glass transition temperature.

• A syringaldehyde derived epoxy resin monomer (SA-TAG-EP) was developed. • The bio-based epoxy system showed a record T g of 224 °C, high strength and modulus. • The bio-based epoxy system showed satisfactory intrinsic flame retardancy. Due to increasing environmental concerns, global warming, and the decline of oil reservoirs, the use of bio-epoxy resins derived from sustainable resources is recommended. The development of bio-based epoxy resins with considerable thermal stability, mechanical strength, and appropriate intrinsic flame retardant potential is highly demanded. In this study, a new Schiff-based epoxy monomer, triglycidyl ether of syringaldehyde (SA-TAG-EP), was synthesized from renewable syringaldehyde. After the 4,4′-diaminodiphenylmethane (DDM)-based curing process, an intrinsically flame-retardant resin (SA-TAG-EP/DDM) with C, H, N, and O elements was achieved. SA-TAG-EP/DDM showed higher glass transition temperature (224.9°C) and greater mechanical strength, including a tensile strength of 66.8 MPa and an elongation at break of 3.91%, compared to petroleum-based bisphenol A epoxy thermoset. It also passed the V-0 flammability rating in the UL-94 test and exhibited a 38.5% limiting oxygen index, 48.9% char yield under N 2 , and a lower peak heat release rate than that of petroleum-based bisphenol A epoxy thermoset. We proposed a simple and sustainable route for the synthesis of Schiff base epoxy compounds from biomass-derived resources, which demonstrates significant mechanical properties and increased flame retardant potential. [ABSTRACT FROM AUTHOR]