Effect of metal oxides on fire resistance and char formation of intumescent flame retardant coating

Metal oxides (MO) can remarkably affect the char formation of intumescent flame retardants (IFR) during thermal decomposition, thereby improving the fire resistance property of IFR coatings. In present work, Fe₂O₃, ZnO and TiO₂ were separately incorporated with caged bicyclic phosphates based IFR in epoxy coating, and their effects on fire resistance and char formation of the IFR coating were investigated. Back temperature test results showed that MO worked synergistically on improving fire resistance of the coating and their effectiveness of improvement followed the trend of Fe₂O₃>ZnO>TiO₂. Thermogravimetric analysis (TGA), laser Raman spectroscopy (LRS) and X-ray photoelectron spectroscopy (XPS) results revealed that MO promoted the formation of pseudo-graphic char with improved thermal stability which still survived at high temperature, and their effectiveness of promotion also followed the trend of Fe₂O₃>ZnO>TiO₂.