Thermal diffusivity of rigid polyurethane foams blown with different hydrocarbons

The insulation properties of rigid polyurethane foams are characterized, amongst others, by the heat flow through the solid phase of the foam, which is one of the participants of the heat transfer. Dependence of the thermal diffusivity on the kind of hydrocarbon blowing agent was studied, where 1-dichIoro-1-fluoroethane was used as a reference blowing agent. Application of a blend of hydrocarbons, with a boiling point in the range 28-63 degrees C, was found to be particularly advantageous to obtain isotropic foams with satisfactory insulation properties. New environmentally-friendly agents, used for foaming of polyurethane, fulfill a double role. They have an influence on the composition of the gas phase within foam cells, and also on the foam morphology. (C) 2000 Elsevier Science Ltd. All rights reserved.