Feasibility analysis of hexaphenoxy cyclotriphosphazene flame retardant for inhibiting electrical tree growth of epoxy resin

Epoxy resin (EP) with excellent electrical and mechanical properties was widely employed as the insulation structure in high-voltage (HV) power equipment. Due to its ultra-high electric field, the inevitable electrical tree aging phenomenon often occurs in the insulation materials, which seriously threatens the safe operation of power equipment. A flame retardant such as hexaphenoxy cyclotriphosphazene (HPCTP) can reduce the intensity of heat release during the thermal decomposition of epoxy groups and consume free radicals generated by the reaction of epoxy molecular chains with oxygen, which provides a potential possibility to inhibit the tree growth in the insulation materials. In this work, the electrical treeing characteristics of the HPCTP/EP composites under high electric field was studied. It's confirmed that the tree growth of HPCTP/EP composites was significantly inhibited by HPCTP. The tree initiation voltage and voltage life of the HPCTP/EP composites are both higher than those of the pure EP. The carbonization in the tree channel was effectively inhibited by HPCTP, which weakened the electric field at the tip of the tree channel, thereby prolonging the voltage life of the HPCTP/EP composites.