Indian Journal of Chemistry Vol 57A, June 2018, pp. 761-769 Deviations in viscosity and thermodynamics of viscous flow for binary mixtures of methyl acrylate with 1-alkanols at different temperatures A K Nain*, P Droliya & J Gupta Department of Chemistry, Dyal Singh College (University of Delhi), New Delhi 110 003, India Email: ak_nain@yahoo.co.in Received 7 November 2017; revised and accepted 14 May 2018 The viscosities (η) of binary mixtures of methyl acrylate with 1-butanol, 1-hexanol, 1-octanol and 1-decanol, including those of pure liquids, over the entire composition range are reported at different temperatures (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 318.15) K. From the experimental data, the deviations in viscosity (Δη) have been calculated. The Δη values are found to be negative over the entire composition range for these mixtures, indicating the presence of weak interactions between methyl acrylate and 1-alkanol molecules. The magnitude of negative deviations in Δη values follows the order: 1-butanol < 1-hexanol < 1-octanol < 1-decanol. It is observed that Δη values depend upon the length of the alkyl chain in 1-alkanols. Also, the interactions between methyl acrylate and 1-alkanols decrease with increase in alkyl chain length. The thermodynamics of viscous flow has been analyzed by using Eyring and Arrhenius approaches and the results have been compared and discussed in terms of intermolecular interactions between the molecules. Further, the viscosities of these binary mixtures computed theoretically by using various empirical and semi-empirical models correlated well with the experimental findings in terms of average standard deviations. Keywords: Solution chemistry, Binary mixtures, Viscosity, Methyl acrylate, Alkanols, Molecular interactions, Thermodynamics of viscous flow The knowledge of physicochemical properties of non-aqueous binary liquid mixtures has relevance in theoretical and applied areas of research, and these data are frequently used in process design (flow, mass transfer, or heat transfer calculations) of many chemical and industrial processes 1-11 . Viscosity and its derived thermodynamic parameters provide important information regarding the nature and strength of intermolecular interactions in liquid mixtures. Experimental viscosity data of liquid mixtures are helpful in developing and testing various theories and models, which can relate experimental data with theoretical models, which further helps in predicting the data without carrying out the experiment. Methyl acrylate is a very important industrial chemical and is widely used commercially for the production of important high polymeric and latex compounds. It is a polar (dipole moment, μ = 1.77 D at 298.15 K) 12 , aprotic and unassociated liquid 12 . On the other hand, alkanols are protic, highly associated through hydrogen bonding and this association decreases with increase in alkyl chain length in 1-alkanol 13 . Therefore, the study of intermolecular interactions in methyl acrylate+1-alkanol mixtures would be interesting owing to their industrial applications 14 . To the best of our knowledge, viscometric studies on binary mixtures of methyl acrylate with 1-butanol, 1-hexanol, 1-octanol and 1-decanol at different temperatures are not reported in the literature, except for the work by Sastry et al. 15 who reported viscosities of methyl acrylate+1-butanol mixtures at 308.15 and 318.15 K. In the present paper, we report the viscosities (η) of binary mixtures of methyl acrylate with 1-butanol, or 1-hexanol, or 1-octanol, or 1-decanol, including those of pure liquids at temperatures (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 318.15) K, covering the entire composition range expressed by the mole fraction, x 1 of MA. The density (ρ) data for the calculations have been taken from our earlier study 16 . From the experimental data, the deviations in viscosity (Δη) have been calculated. The variations of Δη with composition and temperature of the mixtures have been discussed in terms of molecular interaction in these mixtures. The effect of alkyl chain length of 1-alkanol molecules on interactions in these mixtures has also been discussed. The thermodynamics of viscous flow has been analyzed by using Eyring and