Melamine poly(zinc phosphate), MPZnP, a PIN FR combining phosphorus, nitrogen and inorganic zinc was tested as a flame retardant for epoxy resin.
The resin was generated by reacting DGEBA (Araldite MY740) with IPDA (isophorone diamine) and 20% of different PIN FR combinations: MPZnP, melamine polyphosphate (MPP) and aluminium hydroxide AlO(OH). Lowest peak heat release was achieved by combining MPZnP and MPP, five times lower than for non-FR resin, indicative of the effectiveness of these PIN FR systems in reducing fire development. This is considered to be the result of structural resistance of MPZnP – resin char combined with high char expansion by MPP blowing. In all cases, most or all of the phosphorus in the PIN FRs was conserved in the fire residues and not lost in fire gases.
“Melamine poly(zinc phosphate) as flame retardant in epoxy resin: Decomposition pathways, molecular mechanisms and morphology of fire residues”, P. Müller, Polymer Degradation and Stability 130 (2016) 307e319 http://dx.doi.org/10.1016/j.polymdegradstab.2016.06.023