Thermal conductivity of highly oriented polyethylene

We have measured the thermal conductivity of oriented polyethylene both along and perpendicular to the draw direction for draw ratio λ between 1–25 and in the temperature range of 120 to 320K. The results for λ ⩽ 5 have been analysed in terms of the modified Maxwell model while the further increase of thermal conductivity along the draw direction at higher λ has been explained by the Takayanagi model. The Young's modulus and thermal conductivity along the draw direction for the sample with λ = 25 were found to be 64 GN/m 2 (at 220K) and 140 mW/cm K (at 300K), respectively, which are extremely high values for polymers. This material, which is a good electrical insulator and yet has a high thermal conductivity, may be useful in electrical applications requiring large dissipation of heat.