Dimelamine pyrophosphate (DMPY) was synthesised in one step (97% yield) from melamine and sodium pyrophosphate, then tested as a flame retardant in DGEBA/PDA epoxy resin at 0 – 12% loading. UL94-V1 (3.2 mm) was achieved at 8% DMPY and V0 at >9%. LOI was increased by up to 50% (at 12% loading). At 9% DMPY, peak smoke release rate and total smoke production were both reduced by >40%. Moisture resistance and mechanical properties of the FR resin were considered good. The FR resin generated intumescent, coherent and structured char. The authors conclude that DMPY could offer a wide application, low-cost PIN FR solution for epoxies.
“Economical and facile synthesis of a highly efficient flame retardant for simultaneous improvement of fire retardancy, smoke suppression and moisture resistance of epoxy resins”, L. Liu et al., Composites Part B 167 (2019) 422–433, https://doi.org/10.1016/j.compositesb.2019.03.017