The novel arborescent monomolecular P-N intumescent flame retardant hexalis-(4-(5,5-dimehtyl-1,3-dioxaphospho-rinanyl-2-oxy-phosphate-ester-phenoxy))-cyclotriphosphazene (Ⅵ) was synthesized via hexachlorotriphosphazene, 4-methoxyphenol, neopentyl alcohol and phosphous oxychloride by a three step reaction and its structure was identified and studied by FT-IR, ¹H NMR and MS analyses. The termogravimetry showed that the novel flame retardant had high thermal stability and excellent char-forming ability. The beginning temperature of the compound VI decomposition was 270 ℃, and the char yield was about 45.2% at 600 ℃ in N₂. The results demonstrated that the novel arborescent P-N intumescent flame retardant was effective on the flame retardancy of epoxy resin.

Key words: intumescent flame retardant, synthesis, thermal decomposition, epoxy resin