Kapitza resistance and thermal conductivity of Mylar at superfluid helium temperature

The Kapitza resistance and the thermal conductivity of type A Mylar sheets in the temperature range between 1.4 and 2.1 K have been determined. Four sheets with varying thickness from 37 μm to 255 μm, have been tested in steady-state condition. For a small temperature difference (10-30 mK) and heat flux density smaller than 30 Wm−2, the total thermal resistance of the sheet is determined as a function of sheet thickness and bath temperature. The Kapitza resistance is given by RK = (1.28 ± 0.08)T−3 × 10−3 Km2 W−1, and the thermal conductivity, κ = [(8.83 ± 0.75) + (11.73 ± 0.43) × T] × 10−3 Wm−1 K−1.