Synergistic Effect of Hexaphenoxycyclotriphosphazene and Aluminium Tri-Hydroxide on Flame Retardancy and Smoke Suppression of Epoxy Resin

Flame retardancy and smoke suppression of polymer materials are key problems to be considered for applications that have a potential fire hazard. This study selected hexaphenoxycyclotriphosphazene (HPCTP) and aluminium tri-hydroxide (ATH) powder as an integrated flame retardant treatment in epoxy resin (EP) which is usually used as the matrix of a composite. The characteristics of flame retardancy and smoke suppression were investigated. The results showed that when treated with HPCTP and ATH, the resin exhibits superior properties, resisting flame development and smoke release. Based on analysis of the surface structure of the burned materials by scanning electron microscopy-energy dispersive spectroscopy and X-ray photoelectron spectroscopy, it was confirmed that HPCTP and ATH can attract a lot of heat to slow down decomposition of the resin and produce a comprehensive protection system consisting of a non-flammable gas and solid phases during burning. Non-flammable gas can reduce the concentration of flammable gas to inhibit combustion. In addition, H2O vapour can also reduce the concentration of flammable gas to inhibit combustion. Meanwhile, solid phase films can insulate air to slow down combustion and smoke release.