The Thermal Conductivity of Natural Rubber from 134 to 314 K

The thermal conductivity of soft natural rubber, compounded and vulcanized as specified in ASTM recipe 2A, has been measured over a range extending from well below the glass transition to above room temperature. The glass-transition temperature deduced from the thermal- conductivity measurements is 212 K -78 F. Most of the measurements were made at the Natick Laboratories in a guarded-hot-plate apparatus, with silicone rubber pads on either side of the sample. The rest of the measurements were made at the National Bureau of Standards with apparatus and procedures that have been used for many years in reference-standard work. The thermal-conductivity data are believed to be accurate to 3 or better at room temperature and to about 6 at the glass transition and below.