Photothermal Techniques for Thermal Characterization of Linear Alcohols

Photothermal techniques were used for the thermal characterization of linear alcohols. This was carried out by measuring the thermal diffusivity (by means of a photopyroelectric technique) and thermal effusivity (by means of a photoacoustic technique) of ten linear alcohols, from methanol to 1-decanol. The thermal conductivity and specific heat for these substances were obtained by means of their relations with the two previous thermal properties, by using the values reported for the densities of the alcohols. The values of thermal effusivity showed a decreasing behavior with the increase in length of the linear molecule, and the values of thermal diffusivity, on the other hand, showed a similar behavior but only up to 1-pentanol, from which these values began to increase; this latter behavior was also observed, although to a lesser extent, for thermal conductivities. This peculiar behavior for thermal diffusivity and thermal conductivities is attributed to the influence of the hydroxyl group, which is strong for low molecular weight alcohols, but it diminishes as the size of alcohol’s molecule increases.