On the Evacuation of Plastic Foams to Reduce Their Thermal Conductivity

Abstract

The use of plastic foam as a thermal insulator is widely recognized and, in recent years, these foams have been used quite successfully in many cryogenic applications. Realizing the potential of a load-bearing plastic foam as an insulator for air-borne liquid-hydrogen or liquid-oxygen tanks, a test program was initiated to devise a method of reducing the thermal conductivity of such foams. The method that was conceived was simply to evacuate the foam, removing the residual gases within the individual cells, even though the cells were thought to be essentially closed.