Furfural is a natural aldehyde chemical found in or derived from non-food, lignocellulose materials such as wheat bran, corn cobs and sawdust (furfur = latin for bran). A Schiff base (nitrogen containing, imine structure) was derived from furfuran, then reacted with DOPO (9,10‐dihydro‐9‐oxa‐10 phosphaphenanthrene‐10‐oxide), generating a reactive phosphorus-containing flame retardant. At 5% loading in epoxy (DGEBA/DDM 4,4′‐diaminodiphenylmethane), resin impact strength was improved and UL94-V0 (3.2mm) and 37.5% LOI (limiting oxygen index) fire performance were achieved. The P-FR was shown to reduce the release of volatiles gases from the epoxy in fire, acting in both the solid phase (char formation) and in the gas phase.
“Flame retardant and toughening behaviors of bio‐based DOPO containing curing agent in epoxy thermoset”, Z. Yao et al., Polym Adv Technol. 2019;1–11 http://dx.doi.org/10.1002/pat.4782