Viscosities of binary liquid mixtures of some n-alkoxypropanols with n-alkanols at 298.15 K

Abstract

The viscosities (η) in binary liquid mixtures of (n-alkoxypropanols + methanol, ethanol, or I-propanol) have been measured as a function of composition using an Ubbelohde viscometer at 298.15 K and atmospheric pressure over the full range of composition. The n-alkoxypropanols are propylene glycol monomethyl ether (l-methoxy-2-propanol). CH₃OCH₂CH₂CH₂OH, propylene glycol monoethyl ether (l-ethoxy-2-propanol), C₂H₅OCH₂CH₂CH₂OH, propylene glycol monopropyl ether (l-propoxy-2-propanol), C₃H₇OCH₂CH₂CH₂OH, propylene glycol monobutyl ether (l-butoxy-2- propanol), C₄H₉OCH₂CH₂CH₂OH propylene glycol rert-butyl ether (l-rert-butoxy-2-propanol), CH₃CHOHCH₃0C(C₄H₉)₃. The η values for each of the mixture studied are positive over the whole mole fraction range. For all the cases, except propylene glycol rert-butyl ether, η increases in a positive direction with increase in chain length of n-alkoxypropanols. The values of Δη, which refers to the deviation of the experimental values of the dynamic viscosities of the mixtures from the mole fraction mixture law values, are found to be positive for all the mixtures. Further, the excess free energies of activation (ΔG*E) for viscous flow have been calculated from the experimental data. The results for η, Δη, and ΔG*E are discussed in terms of interactions between the components of the mixtures. Equations such as Heric's, Auslaender's, and MeAllister's four-body interaction model have been used to correlate the kinematic viscosities,