Probing the intermolecular interactions in N-methylacetamide + polyethylene glycol 200/300/400 binary mixtures by means of physicochemical properties and FTIR spectra: Experimental and theoretical study

The molecular interactions in N-methylacetamide (NMA) + polyethylene glycol (PEG) mixtures are studied from the measurements of the densities, ρ and speeds of sound, u of NMA + PEG 200, PEG 300 and PEG 400 mixtures across the entire range of composition at temperatures, T/K = (293.15–323.15) and pressure, p = 100 kPa. The experimental ρ and u data were correlated using the Jouyban-Acree model to check their composition and temperature dependence. The excess parameters, viz., excess molar volume, excess isentropic compressibility, excess intermolecular free length, excess molar isentropic compressibility and excess acoustic impedance were calculated from the measured data. Further, the partial molar volume/compressibility; excess partial molar volume/compressibility of the components over the entire composition range and at infinite dilution were also calculated. These parameters have been interpreted in terms of molecular interactions in these systems. PC-SAFT was successfully applied as a predictive and fitted approach for density modeling of these mixtures. Furthermore, it was found that with the fitted approach, the best results were obtained for modeling the excess molar volumes. Additionally, the speeds of sound have been evaluated theoretically by means of various theories/relations and the results were compared with experimental data. Also, the FT-IR spectra of pure NMA, PEG and near equimolar NMA + PEG mixture were recorded and examined to substantiate the nature and extent of prevailing intermolecular interactions.