Low temperature thermal conductivity of polyamide-imide

Thermal conductivity of polyamide-imide Torlon 4203 was measured at tempera tures between 0.1K and 1K. The measurements were carried out in a dilution refrigerator using a steady state technique. The fit on the data gave a temperature dependence of the conductivity : k = alpha .T-n, with n = 2.23 +/- 0.01 and alpha = (7.72 +/- 0.08) . 10(-5)W/c mK(n+1). A quadratic dependence on T of the conductivity can be explained, within th e framework of the tunneling model, as being due to the resonant scattering of phonons by two level systems.