Thermal Conductivity of Selected Foams and Systems from 100 to 300 K.
Final rept. May-Jul 86,
NATIONAL BUREAU OF STANDARDS GAITHERSBURG MD
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The apparent thermal conductivity of five insulating materials was determined in the nominal temperature range from 100 to 300 K -280 to 80 deg F. A guarded hot plate apparatus was used and the testing environment was dry nitrogen gas at near ambient pressure. One specimen was retested in a vacuum environment. Three of the specimens were neat polymethacrylimide PMA foams with nominal densities of 51 and 71 kgm3 3.2 and 4.4 lbft3. Other specimens tested were a polyurethane foam sprayed on an aluminum substrate and a sandwich construction specimen utilizing PMA foam of nominal density 110 kgm3 6.9 lbft3. The results in nitrogen gas show the expected conductivity increase with increasing density. The observed conductivity at 0.67 Pa 5 micrometers of Hg is significantly lower than that in ambient pressure nitrogen gas. The large relative difference may be due to increased thermal resistance at the plate specimen boundaries.