Polyaniline-modified Fe₂O₃ / expandable graphite: A system for promoting the flame retardancy, mechanical properties and electrical properties of epoxy resin

A flame retardant was synthesized with polyaniline modified Fe₂O₃ (PANI@Fe₂O₃). Upon the incorporation of expandable graphite and PANI@Fe₂O₃, the resulting epoxy resin composite exhibited significant flame retardant activity in the condensed phase by forming a worm-like laminated carbon layer which constituted of the benzene ring, Si–O and Si–N bonds. The limit oxygen index of the EP composite loaded with 7 wt% EG and 1 wt% PANI@Fe₂O₃ (EP/7EG/1PANI@Fe₂O₃) was increased from 20.7% of EP to 34.6%, scoring the V-0 level in the UL-94 test. The total heat release and total smoke release of EP/7EG/1PANI@Fe₂O₃ were 31.3% and 55.5% lower than those of EP, respectively. Meanwhile, with the addition of 4 wt% EG and 4 wt% PANI@Fe₂O₃, the tensile and flexural strength of EP composites were 23.5% and 62.7% higher than those of EP loaded with 8 wt% EG, respectively. Besides, the surface resistivity of EP/7EG/1PANI@Fe₂O₃ was 73% lower than that of EP.