Improving fire resistance of epoxy resin using electrolytic manganese residue-based zeolites modified with metal–organic framework ligands

Epoxy resins (EPs) have limited comprehensive applications because of their flammability. This current work combines 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and a ligand of a metal–organic framework with zeolites prepared from electrolytic manganese residue as flame retardants (D-CoZ-BDC-1), which is reported for the first time. The flame retardant EP composite (EP/D-CoZ-BDC-1) exhibited a limiting oxygen index of 31.0%. The peak heat release rate, total heat release, peak smoke release rate, total smoke release, CO yield, and CO₂ yield of EP/D-CoZ-BDC-1 were reduced by 63.4%, 48.9%, 52.8%, 60.1%, 30%, and 48.7%, respectively, when compared with those for EP. The synergistic effects of pyrolysis in the formation of Co₃O₄, the phospholipid biphenyl structure, Al₂O₃ and SiO₂ in the condensed phase, and PO· in the gas phase gave excellent fire resistance. The proposed method not only produced highly efficient EP flame retardants but could also provide ideas for the design of zeolite-based flame retardants for wider applications.