Maimoona Yasmin

Acoustical study of molecular interactions in polymer solutions through various thermodynamical parameters and Flory's theory at 298.15 K

This study intends to portray the nature of polymer solutions by ultrasonic velocity and density data. Acoustical parameters, such as relaxation strength, relative association, molecular constant, fractional free volume, available volume, Beyers non-linearity parameter, internal pressure, van der Waals’ constants and molecular radius have been computed for the binary mixtures of PEG400 + methanol, PEG400 + ethanol, PPG400 + ethanol and PPG400 + 2-propanol systems at 298.15 K. Florys theory has been used for computing ultrasonic velocity, surface tension, thermal expansion coefficient, thermal conductivity, excess heat capacity and excess isothermal compressibility. Isothermal compressibilities of mixtures have been theoretically evaluated using different theories. A new relation has been proposed by us for evaluating excess molar volume using ultrasonic velocity of the mixture which gives fairly good result when compared with the experimental values. Excess molar volume has been calculated using Florys theory and Prigogine–Flory–Patterson theory. The partial molar volume and its excess value at infinite dilution have also been evaluated.

Study of molecular interactions in binary mixtures of formamide with 2-methoxyethanol and 2-ethoxyethanol at varying temperatures

The thermophysical properties of binary mixtures of formamide with 2-methoxyethanol and 2-ethoxyethanol have been investigated in this article. Densities, refractive index, ultrasonic velocity and viscosity for the two binary mixtures viz. formamide with 2-methoxyethanol and 2-ethoxyethanol have been measured over the entire composition range at 293, 303 and 313 K and at atmospheric pressure. The excess molar volume, the molar refraction deviation, excess Gibbs free energy of activation for viscous flow, excess isentropic compressibility, deviation in viscosity, excess free volume and excess molar enthalpy have been computed using experimental data. These excess parameters have been correlated with Redlich–Kister polynomial equation. The results have been interpreted on the basis of strength of intermolecular interaction occurring in these mixtures. Densities, refractive index and ultrasonic velocity were correlated with second-order polynomial equation. The molar volume and excess partial molar volume at infinite dilution have also been calculated for both the mixtures.

Thermoacoustical study of molecular interactions in binary mixtures of pentane with methanol and tert-butanol

Experimental values of density, ultrasonic velocity and viscosity for the binary mixtures of pentane with methanol and tert-butanol have been measured at 293.15, 298.15 and 303.15 K over the entire composition range. Using these experimental data, specific heat ratio, heat capacity, effective Debye temperature, pseudo-Grüneisen parameter, viscosity deviation, excess internal pressure, excess Gibbs free energy of activation for viscous flow and excess molar enthalpy have been calculated and computed results were fitted to the Redlich-Kister polynomial equation. These parameters were used to study the nature and extent of intermolecular interaction between components molecules present in the binary mixtures. The results suggest that stronger specific interactions are taking place in pentane + methanol mixture than in pentane + tert-butanol mixture. Furthermore, various empirical relations were used to correlate the ultrasonic velocities of these mixtures. An excellent agreement has been found between experimental and theoretical values.