Problems in Predicting the Thermal Properties of Faced Polyurethane Foams

The thermal properties of polyurethane foams vary during service life depending on environmental conditions, the manner in which they are enclosed in the building partition, or if covered with facing membranes during their production. The effect of facing materials on thermal performance of the composites may range from a slight improvement of dimensional stability to a substantial reduction in the rate of loss of thermal resistance. Faced polyurethanes should be tested as composite materials, using a method that simulates performance conditions as closely as possible. Such a test method should include determination of cell gas composition as a measure of the aging process. Determination of cell gas composition after a period of exposure to different service conditions would allow an approximate correlation of laboratory results with in situ performance. The paper gives background information on effects of environmental factors and aging simulations on thermal resistance of polyurethanes and provides a starting point for discussion of the testing method.