Construction of an organic iron phosphate/graphite carbon nitride hybrid system for improved fire safety of epoxy resin

Enhancing the fire safety of epoxy resin (EP) is crucial due to its widespread but inherent flammability , necessitating the integration of additive flame retardants (FRs) that are effective in small quantities and exhibit efficient flame retardancy. This study constructed a novel, efficient FR by synthesizing organic iron phosphate (ATMP-Fe) and loading it on graphitic carbon nitride (g-C 3 N 4 ). The resulting hybrid flame retardant (ATMP-Fe/g-C 3 N 4 ) was added to EP in minimal amount to bolster its flame retardancy and safety features. Incorporating a mere 3 wt% of ATMP-Fe/g-C 3 N 4 into EP significantly improved its flame retardancy and thermal stability. This was evidenced by an increase in the limiting oxygen index from 25.5% for EP to 30.1%, achieving a V-1 rating in the UL-94 test, and producing a 22.0 wt% char residue . Moreover, there was a substantial reduction in peak heat release rate , total heat release, and total smoke production by 36.3%, 27.5%, and 39.3%, respectively. The reduction in pyrolysis products, along with the formation of a dense and stable char layer facilitated by the synergistic effects of phosphorus and iron elements, significantly improved the fire safety of EP. Additionally, the enhanced hydrophobicity , mechanical properties, and electrical conductivity of the EP/3ATMP-Fe/g-C 3 N 4 composite suggested potential for wider application of EP in various fields.