Flame-retardant epoxy resin based on aluminum monomethylphosphinate

Aluminum monomethylphosphinate (MeP-Al) was synthesized and applied as a flame retardant for epoxy resin (EP). The structure of MeP-Al was characterized with FTIR, 1H NMR, 31P NMR and XRF. Curing reaction monitoring, thermal analysis, evolved gas and solid residue analysis, flammability tests (LOI, UL 94), microcombustion calorimeter and chemical analysis of residues were used. 20 mass% of MeP-Al provides EP with desired flame retardancy and anti-dripping property. The formulation passes the UL 94 V0 rating with LOI value of 29.6 %. MeP-Al mainly acts in the solid phase, and minority acts in the gas phase. P–H bond in MeP-Al can react with the unsaturated bond of compounds coming from decomposition of EP to form the condensed and stable phosphate salts in the solid phase. The firm char is a good barrier to avoid heat transfer and progressive degrading of the inner material.