Isochoric thermal conductivity of solid 2-propanol

Abstract

The isochoric thermal conductivity of solid 2-propanol (C3H7OH) was measured for samples of different densities, in the temperature range from 140 K up to melting. It was found that thermal expansion significantly affects the temperature dependence of thermal conductivity in monohydric alcohols studied at pre-melting temperatures. The isochoric thermal conductivity of all samples decreased with increasing temperature weaker than at a saturated vapor pressure, and deviates strongly from the k ∝ 1/T dependence. We describe the experimental results in the framework of a model involving thermal transfer by the propagons and diffusons; further, we discuss its principled difference from the simple Debye model, which does not take into account the dispersion and real density of phonon states. The contributions of propagons and diffusons in 1-and 2-propanol are calculated, and a comparison of thermal conductivities of isomers performed. It was found that the contribution of the diffusons is much higher than that of the propagons, and, in 2-propanol, both contributions are significantly smaller than in 1 - propanol. It was shown that the coefficients Ai responsible for the contribution of the propagons were essentially dependent on the density, while the coefficients Bi describing the contribution of the diffusons were practically constant.