Effect of Phospho-Halogenated Polyethcr Polyol on Fire Behaviour of Rigid Polyurethane Foams Blown with Various Agents

The substitution of CFC-11 with blowing agents with low environmental impact, for the production of PU thermal insulating materials, implies the variation of several properties of the material. The worsening of fire behaviour of material, based on Ixol B 251, with flammable blowing agents (HCFC-141b, 2-chloro propane and n-pentane) can be reduced by modifying the formulation, i.e. by increasing the amount of flame retardants. The results of the Oxygen Index test were compared with the data obtained from the ISO 3582, DIN 4102 - B2 and UNI 9177 test and gave a good correlation. The initial thermal conductivity of the various foams is strictly linked with the thermal conductivity of the gas phase and increases with the new blowing agents and particularly in the case of n-pentane reaches values which are about 20% higher than that of foams blown with CFC-11. Hydrocarbon type blowing agents do not change significantly the mechanical properties of the materials; small variations in mechanical properties with HCFC-141b should be attributed to the solvent action of the compound on the polymer matrix.