Intermolecular Interactions in 1,6-Diaminohexane + Water Mixtures at 293.15 to 333.15 K

Abstract

The density (ρ) and viscosity (η) of the mixtures of 1,6-diaminohexane (DAH) + water binary system were determined over the whole composition range at p = 101 kPa from 293.15 to 333.15 K. The measured density and viscosity values decrease with the increase of temperature. In addition, the viscosity of the binary system shows a maximum value along with the molar fraction of DAH. According to the experimental data, excess molar volume (VE), apparent molar volume Vϕ, viscosity deviation (Δη), and excess Gibbs free energy (ΔG*E) of the activation of viscous flow were obtained and correlated by the well-known Redlich–Kister type polynomial equation by using the least square method and regression parameters were calculated. It was found that all of the VE values are negative while $$\Delta \eta $$ and ΔG*E values are positive. The intermolecular interactions between DAH and water were characterized by the averaged non-covalent interaction index (aNCI) and thermal fluctuation index (TFI) method. The obtained results proved that N···H–O and O···H–N hydrogen bonds which lightly affected by thermal motion, and some of the flexible van der Waals interactions are the reason for the specific variation of the viscosity and excess properties of the studied binary system.