Ultrafine iron oxide decorated mesoporous carbon nanotubes as highly efficient flame retardant in epoxy nanocomposites via catalytic charring effect

The decoration of transition metal on carbon family materials have showed great effectiveness in the preparation of flame retardant epoxy based composites. In this study, polydopamine assisted surface modification of carbon nanotubes were provided to synthesize ultrafine iron oxide decorated porous carbon nanotubes. The calcinated carbon nanotubes with a high specific surface area and mesoporous characteristics were introduced into epoxy resin as the non-toxic flame retardant additives. With a low loading of 0.3 wt%, the functionalized carbon nanotubes acted as the highly efficient flame retardant in epoxy nanocomposites, reflecting by the high limiting oxygen index of 30.1%, a 42.2% reduction of peak heat release rate, and a 52.6% reduction of total smoke production. It is clearly revealed that via the catalytic charring actions in condensed phase, the multi-layered and dense char barriers were formed under combustion, thus effectively retarded the mass and heat transfer in combustion. In addition, mechanical performances, including the modulus and hardness of EP nanocomposites were also reinforced with the addition of as-synthesized CNT derivatives. This study offers an innovative strategy to prepared non-toxic and high-efficient flame retardant nanofillers based on carbon family materials.