Halogen-free flame retardants for polymeric foams

The effectiveness of some mixtures of halogen-free flame retardants (i.e. expandable graphite, triethylphosphate and red phosphor-us) in flame retardancy of polyisocyanurate-polyurethane (PIR-PUR) foams, blown with n-pentane, has been investigated by means of DIN 4102-B2 and oxygen index tests. The thermal stability and mechanical properties of PIR-PUR filled foams have also been considered. The results showed that the introduction of increasing amounts of expandable graphite, into foams containing triethylphosphate or red phosphorus, causes a significant worsening of physical-mechanical properties. The fire behaviour characterisation has demonstrated that the introduction of such flame retardants as fillers leads to a great improvement particularly for foams filled with expandable graphite and triethylphosphate. Also significant improvement has been observed in thermal stability due to the presence of flame retardants.