Thermodynamics of mixtures with strongly negative deviations from Raoult's law. XI. Densities, viscosities and refractives indices at (293.15-303.15) K for cyclohexylamine + 1-propanol, or +1-butanol systems

The thermophysical properties densities, ρ, kinetic viscosities, ν, and refractive indices, nD, have been measured at atmospheric pressure and at (293.15-303.15) K for the mixtures cyclohexylamine + 1-propanol, or +1-butanol. The experimental ρ, ν, nD values were obtained using an Anton Paar DMA 602 vibrating-tube densimeter, an Ubbelohde viscosimeter and a refractometer model RMF970, respectively. Densities values are used to determine the molar excess volumes, VmE, and, together with ν values, the dynamic viscosities (η). Deviations from the ideal state,ΔnD, and deviation from linear dependence on mole fraction for viscosity, Δη, are also reported. The large negative VmE values obtained reveal the existence of strong interactions between unlike molecules. This is supported by the positive values of Δη and by the quadratic dependence of nDwith mole fraction. The temperature dependences of η and of the molar volume have been used to evaluate the enthalpy and entropy of viscous flow. It is shown that Gibbs energy of viscous flow,ΔG*, is essentially determined by enthalpic effects. Viscosity data have been correlated by the semi-empirical equations: Grunberg-Nissan, Hind, Frenkel, Katti-Chaudhri, Teja-Rice, McAllister and Heric. The deviations obtained are between 1% and 2%

Highlights► ρ, η and nDwere determined at (293.15-303.15) K for C6H11NH2 + 1-propanol, +1-butanol. ► Large negative VmEs reveal the existence of strong interactions between unlike molecules. ► This is supported by the positive values of Δη and by parabolic shape of nD(x1). ► Dependences with T of η and ρ are used to evaluate the enthalpy and entropy of viscous flow. ► ΔG* is essentially determined by enthalpic effects.