Imparting high flame retardancy to epoxy resin with ultra-low loading of 5,10-dihydro-phenophosphazine-10-oxide functioned triazine

High mechanical properties and flame retardancy of epoxy are important for its applications. A novel star-shaped flame-retardant 5,10-dihydro-phenohphosphazine-10-oxide functioned triazine (TRIDPPA) with high efficiency is synthesized, and its structure is characterized. TRIDPPA is used as the co-curing agent for diglycidyl ether of the bisphenol A/4,4-diaminodiphenyl methane system. The introduction of TRIDPPA greatly improves the flame retardancy of the cured epoxy resins. The epoxy resin (ER)/TRIDDPA1.0 resin acquires a limiting oxygen index value of 30.7% and UL-94 V-0 rating when the mass fraction of TRIDDPA is 1.0 wt% with only 0.086 wt% of phosphorus content. The cross-link density of ER/TRIDDPA1.0 is increased, and the glass transition temperature is improved by 5°C. Besides, tensile strength and toughness of ER/TRIDDPA1.0 are also enhanced.