Abstract: Hexakis(phenoxy) cyclotriphosphazene (HPCP) was prepared using homemade hexachlorocyclotriphosphazene through nucleophilic substitution reaction. The prepared HPCP was introduced into epoxy resin (EP) as a flame retardant and the thermal degradation properties and mechanism were characterized by LOI and TG-MS. It showed that the char yield increased obviously by the addition of HPCP and the LOI of EP/HPCP system with 10 phr HPCP increased to 27.0 %. The flame retardancy could be explained as the results of N-P synergistic effect and release of H2O from the self-condensation of HPCP.

Key words: hexakis(phenoxy) cyclotriphosphazene, epoxy resin, flame retardancy, thermal degradation