Influence of ferric phosphate on smoke suppression properties and combustion behavior of intumescent flame retardant epoxy composites

Abstract

This article mainly studies the smoke suppression properties and synergistic flame retardant effect of ferric phosphate (FeP) on flame retardant epoxy resin (EP) using ammonium polyphosphate and pentaerythritol as intumescent flame retardants (IFRs). Then, the smoke suppression and synergistic flame retardant properties of FeP on IFREP composites were evaluated using cone calorimeter test (CCT) and scanning electron microscopy (SEM). The influence of FeP on thermal degradation of IFREP was studied by thermogravimetric analysis/infrared spectrometry in nitrogen atmosphere. Remarkably, the CCT results show that FeP can effectively decrease heat release rate, total heat release, smoke production rate, total smoke production, and smoke factor of flame retardant samples. The SEM results show that FeP can greatly improve the structure of char residue. The TGA results indicate that the material with FeP undergoes degradation in three characteristic temperature stages, which can be attributed to the catalyzing deamination by FeP, the reaction between polyphosphoric acid and FeP, and the rupture of the polyphosphoric acid chain, respectively. The volatilized products formed on thermal degradation of IFREP indicate that the volatilized products are H2O, CO2, CO, carboxylic acid, and aliphatic hydrocarbons according to the temperature of onset formation. Here, FeP is considered to be an effective smoke suppression agent and a good synergism in IFREP composites, which can greatly improve the structure of char residue.