Acoustic and volumetric studies of binary mixtures of 1,3-butanediol + 1-pentanol

The results of acoustic and volumetric investigations of binary liquid mixtures of 1,3-butanediol with 1 -pentanol at the temperatures (298.15, 308.15, and 318.15) K are presented. Basing on the phase speed of ultrasound values (measured by the pulse-echo-overlap method at 2.18 MHz) and densities, the excess values of the molar volume and isentropic compressibility (volume-specific and molar), were calculated. Their composition dependencies were expressed by Redlich-Kister polynomials. It turned out that mixing of 1,3-butanediol with 1-pentanol, results in an enhanced rigidity of the mixtures in comparison with that of the pure components. What is more, this rigidity increases with increasing temperature. At the same time the volume effects (expansion) upon mixing increase with increasing temperature too. The results are discussed in terms of the variations of the structure and molecular interactions.