In situ fabrication of melamine hydroxy ethylidene diphosphonate wrapped montmorillonite for reducing the fire hazards of epoxy resin

Abstract Epoxy resin (EP) suffers from inherent flammability, many efforts had been made to address this issue. In this work, melamine hydroxy ethylidene diphosphonate wrapped montmorillonite (Mt@MHEDP) was successfully prepared through in situ fabrication to endow EP with lower fire hazards. The prepared Mt@MHEDP was well characterized by XRD, FTIR and SEM-EDS, a series of EP/Mt@MHEDP composites were prepared. The fire performance and thermal stability of EP composites were evaluated by LOI, cone calorimeter test and TGA. The flame-retardant mechanism was investigated by SEM and TG-IR. Due to the presence of MHEDP particles on Mt, the prepared Mt@MHEDP was dispersed uniformly in the EP matrix. From cone test, peak heat release rate (p-HRR) and flame growth index (FGI) of EP composites were reduced by 31.7% and 38.6%, respectively, with the addition of 8 wt% Mt@MHEDP. Moreover, the peak smoke production rate (p-SPR) and peak CO production rate were decreased by 30.9% and 40.4%, respectively. From TG-IR, the release of toxic CO and organic volatiles during the decomposition was decreased significantly, implying the lower toxicity and higher fire safety. The enhanced flame retardancy, suppressed smoke production and lower toxicity can be attributed to the synergetic effect of Mt and MHEDP.