Anomaly in temperature dependence of thermal transport of two hydrogen-bonded glass-forming liquids

The thermal conductivity of two molecular glasses (ethanol and 1-propanol) decrease with increasing temperature up to their glass transitions at T-g approximate to 97 and 98 K, respectively. Within their supercooled liquid phases, the conductivity increases with rising temperature up to a maximum which roughly coincides with the liquidus (or melting temperatures T-m approximate to 159 K and T-m approximate to 149 K, respectively). From there on, the conductivity decreases with increasing temperature, a behavior common to most liquids examined so far, exception made of liquid water. The origin of the rather different dependencies with temperature of thermal transport is understood as a competition between phonon-assisted and diffusive transport effects which are amenable to experiments using high resolution quasielastic neutron scattering and visible and ultraviolet Brillouin light-scattering spectroscopies.