Influence of different flame retardants on fire behaviour of modified PIR/PUR polymers

The influence of some halogen-free flame retardants (ammonium polyphosphate or ammonium polyphosphate + melamine cyanurate) on fire behaviour of modified polyisocyanurate/polyurethane (PIR/PUR) foams, with a constant isocyanate index equal to 200, have been studied by means of a cone calorimeter. Foams were prepared from isocyanates modified with adipic acid, in order to obtain amide-modified isocyanurate foams that exhibit better thermal stability performance than polyurethane and lower friability than unmodified polyisocyanurate foams. The results obtained demonstrate that an increasing amount of filler causes a slight worsening of physical and mechanical properties, On the other hand, the cone calorimeter results show that the presence of melamine, which causes a rapid decrease of rate of heat release (RHR) and rate of weight loss, considerably improves the fire behaviour of the foams.