Viscosity and excess molar volume of binary mixtures of methanol with n-butylamine and di-n-butylamine at 303.15, 313.15 and 323.15Â K. Characterization in terms of ERAS model

The excess molar volume VmE, viscosity deviation Δη, and excess Gibbs energy of activation ΔG⁎E of viscous flow have been investigated from the density ρ and viscosity η measurements of binary mixtures of methanol with n-butylamine and di-n-butylamine over the entire range of mole fractions at 303.15, 313.15, and 323.15 K. The systems studied exhibit very strong cross association through strong O-H…N bonding between -OH and -NH- groups. As a consequence of this strong intermolecular association, both the systems have very large negative VmE and positive Δη and ΔG⁎E over entire range of composition and at all the temperatures of investigation. VmE of the studied mixtures is consistently described by the ERAS model. The values of cross association constants KAB illustrate that cross-associates are more pronounced in primary amine mixtures than that in secondary amine.