Thermal Conductivity Reduction of Polyurethane Insulating Foam by In Situ Carbon Dioxide Removal

Abstract

Polyurethane foam of the type used for most refrigerator insulation is currently blown in the United States with a mixture of diclorofluoroethane (R-141b), and CO₂. The object of this work has been to reduce the thermal conductivity of this foam by passively removing CO₂ from the cell gas of the foam. This work is applicable to foams blown with R-141b, R-356, cyclopentane, and other low-boiling liquids plus CO₂. In work with hand-mixed foams we demonstrated that NaOH in the form of beads or powder is an effective material for in situ CO₂ removal from foam. After removal of CO₂, originally present at 14%, foam thermal conductivity at refrigerator operating conditions was reduced 9%.