New DOPO-based Flame Retardants: Synthesis and Flame-retardant Properties of Modified Epoxy Resin

We aimed to enhance the flame retardancy of epoxy resin (EP) by synthesizing a novel, halogen-free flame retardant through a one-pot method. The synthesis utilized 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), furfurylamine (FA), and benzene propionaldehyde (BPA) as raw materials. We conducted differential scanning calorimetry (DSC) analysis to investigate the effects of FPD on the curing process and thermal properties of EP. Our findings reveal that incorporating FPD into EP can facilitate a faster curing process and increase the carbon residue post-combustion. Specifically, the FPD/EP-7 composite demonstrates a limiting oxygen index (LOI) of 34.9% and achieves a UL-94V-0 rating with a phosphorus content of 0.91wt%. These results indicate that FPD significantly enhances the thermal stability and charring rate of EP, thereby improving its flame retardancy. Although the addition of FPD slightly reduces the mechanical properties of EP, the composite material maintains excellent performance.