Iron alginate at 8% w/w in epoxy resin halved both peak heat release rate and smoke release rate in epoxy. Iron alginate was produced by aqueous reaction of sodium alginate, which can be extracted from marine plants, with the ferric salts, then dried, pulverised and mixed into epoxy resin during curing. With 7.9% w/w iron alginate, pHRR (peak heat release rate) was reduced by 52% compared to neat epoxy, peak smoke production rate by 48% and total smoke production by 13%, with even greater reductions at 14.6% w/w. Release of volatile hydrocarbons and carbon monoxide during combustion were reduced, contributing to lower flammability and toxicity. Mechanical properties of the epoxy were not deteriorated and impact strength was increased. The fire resistance effect of the iron alginate is shown to result from lower volatile gas emissions and compact char formation.
“Epoxy/iron alginate composites with improved fire resistance, smoke suppression and mechanical properties”, C. Liu et al., J Mater Sci (2022) 57:2567–2583 https://doi.org/10.1007/s10853-021-06671-x