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. (C) 2002 Elsevier Science Ltd. All rights reserved.