Ferric phosphate provides smoke suppression in epoxy
Ferric phosphate (FePO4) at 0.5 – 3 wt% was tested as a synergist in PIN flame retarded epoxy resin (EP-44, MTHPA curing agent), in a 3 mm sheet. The PIN FR ammonium polyphosphate (APP) was used at 27-30 wt%. Addition of ferric phosphate somewhat reduced peak heat release rate, mass loss, total heat release, but in particular very greatly reduced smoke release rate, total smoke release and smoke factor.
The ferric phosphate showed to considerably improve the char structure. The authors suggest that it acts by catalysing de-amination of APP. They conclude that ferric phosphate provides excellent smoke suppression in epoxy, offering important application opportunities.“Influence of ferric phosphate on smoke suppression properties and combustion behavior of intumescent flame retardant epoxy composites”, L. Liu et al. Iran Polm J, 2015 http://link.springer.com/article/10.1007/s13726-015-0327-2