Functionalized Montmorillonite Intercalation Iron Compounds for Improving Flame Retardancy of Epoxy Resin Nanocomposites

To endow montmorillonite with excellent flame retardancy, montmorillonite (Mt) intercalation iron compounds (Fe-Mt) were synthesized and modified by phosphorylated chitosan (PCTS) to prepare PCTS modified Fe-Mt (PCTS-Fe-OMt). PCTS-Fe-OMt was further incorporated into epoxy resin (EP) for improving the fire safety of EP The results revealed that the interlayer spacing of Fe-Mt was expanded by PCTS, which resulted in well dispersion of PCTS-Fe-OMt in EP matrix. The TGA results showed that EP/PCTS-Fe-OMt nanocomposites exhibited much higher residues due to the excellent charring performance of PCTS-Fe-OMt. According to the cone calorimeter tests, the addition of 5 wt% PCTS-Fe-OMt made peak heat release rate, total heat release, peak smoke production rate, total smoke production values of EP observably decrease by 40.2%, 17.1%, 33.9% and 19.0%. Based on the above results, the improved flame retardancy and smoke suppression properties of EP/PCTS-Fe-OMt nanocomposites were attributed to the combination of iron compounds and phosphorylated chitosan on catalytic charring, thereby promoting the formation of swollen, continuous and compact char layers on the surface of polymer during combustion, eventually restraining the decomposition of polymers.