A green flame retardant by elaborate designing towards multifunctional fire-safety epoxy resin composites

With the specialization and diversification of the use environment of composite products, composite materials should have good comprehensive properties. Abiding by this target, we successfully prepared a transparent epoxy resin (EP) composite with flame retardancy, low smoke, enhanced toughness, high glass transition temperature by blending the flame-retardant POI synthesized in this work. POI was synthesized from phospho-phenanthrene, vanillin and histidine, and the combination of these three raw meticulously selected endowed POI molecule with excellent versatility. EP composite modified with 10 wt% POI (EP/POI-10) obtained a limiting oxygen index (LOI) of 30.5% and received the V-0 grade (UL-94). The reduction of total smoke production by 78.1% via cone calorimeter tests was obtained. The impact strength of EP/POI-7 increased by 48.2% due to the energy dissipation of cracks from POI. The comprehensive analysis of the dual-phase revealed that the improvement of flame retardance was attributed to the joint action of the gaseous phosphorus free radicals quenching and the protecting of condensed coke. Moreover, EP/POI obtained high glass transition temperature as well as good transparency.

Automated summary

By modifying epoxy resin with synthesized flame-retardant POI, we successfully prepared a transparent composite material with flame retardancy, low smoke, enhanced toughness, and high glass transition temperature. The modified composite material achieved a high limiting oxygen index, reduced smoke production, and increased impact strength. Comprehensive analysis revealed that the improved flame retardance was due to the joint action of quenching of gaseous phosphorus free radicals and protection of condensed coke.