Facile Synthesis of a Novel Bio-Based P-N Containing Flame Retardant for Effectively Reducing the Fire Hazards of Epoxy Resin

In this work, a bio-based flame retardant (Cy-HEDP) was synthesized from cytosine and HEDP through a facile salt-forming reaction and embedded into epoxy matrix to improve the flame retardancy and smoke suppression performance. The product Cy-HEDP was well characterized by FTIR, H-1 and P-31 NMR and SEM tests. On the basis of the results, by adding 15 wt% Cy-HEDP, the EP15 can pass UL-94 V-0 rating, and the total smoke production (TSP) as well as total heat release (THR) can be decreased by 61.05% (from 22.61 to 8.7 m(2)/m(2)) and 39.44% (from 103.19 to 62.50 MJ/m(2)) in comparison to the unfilled EP, reflecting the attenuated smoke toxicity and impeded heat generation. According to the analysis results of residual char, it can be concluded that Cy-HEDP possessed the ability to promote the formation of continuous and dense char layers, which would be a physical barrier to insulate oxygen and prevent heat feedback during the combustion of EP. This work provide inspiration towards developing bio-based flame retardant, probably extending the prospects to other polymeric material system.