Fire-retardant, smoke-suppressive and sustainable diatomite-based auxiliaries for highly fire-resistant epoxy resin

Herein, a novel flame retardant and smoke suppression auxiliaries was synthesized with the motivation of sustainability strategy. Porous diatomite (p-DIA) as a purely natural raw material and melamine formaldehyde-phytic acid (MFPA) as a synergist to produce DMFPA, which acts as the novel auxiliaries to endow epoxy resin (EP) with excellent fire safety. The thermal stability of EP composites with 15 wt% DMFPA was improved, as evidenced by a 31.0% reduction in its maximum thermal decomposition rate and an enhancement of residual char to 22.7 wt%. Moreover, EP composites also exhibited superior flame retardant and smoke reduction properties, as reflected by its peak heat release rate (PHRR), peak smoke release rate (PSPR), peak CO release rate and smoke factor (SF) that were 56.5%, 56.3%, 58.7% and 77.7% less than those of unmodified EP, respectively. These results correlated strongly with the powerful adsorption of smoke and flammable debris by porous diatomite, the physical barrier effect of the highly stable expanded char layer facilitated by DMFPA, the dilution effect of non-flammable gases resulted from pyrolysis by melamine and the free radicals quenching effect produced by phytic acid.