甲酰胺+乙醇/丙醇/异丙醇/乙酸乙酯二元混合物的体积及黏度性质

Volumetric and Viscous Properties for Binary Mixtures of Formamide and Ethanol/Propanol/Isopropanol/Ethyl Acetate

为理解含甲酰胺二元溶液的超额性质变化及分子间相互作用,常压下测定了甲酰胺(FA)分别与乙醇、丙醇、异丙醇和乙酸乙酯组成的二元系在293.15~318.15 K的密度和黏度,计算了超额摩尔体积(VE)和黏度偏差(Δη)。采用半经验的黏度方程对实验黏度数据进行了关联和预测,并基于Eyring绝对速率理论方法计算了黏滞性活化参数。结果表明,四个二元系的超额摩尔体积均为负值,且都随温度升高而偏差增大。FA-乙醇和FA-乙酸乙酯两个体系的黏度偏差为负值,且随温度降低而偏差增大。FA-丙醇和FA-异丙醇两个体系的黏度偏差随FA组分增加呈‘S’形变化,在甲酰胺低浓度区由负值变为正值,也均随温度降低而偏差增大。Mc Allister模型对黏度数据的关联结果最好,预测值与实验值的平均相对偏差最小。黏滞性活化参数说明混合过程中焓驱动起主导作用。

In order to study the excess properties and intermolecular interactions of formamide-containing binary solutions, the densities and viscosities of binary mixtures containing formamide （FA） and ethanol, propanol, isopropanol or ethyl acetate were determined at 293.15-318.15 K under atmospheric pressure. Excess molar volumes （VE） and viscosity deviations （△η） were calculated. Moreover, the viscosities of the binary mixtures were correlated and predicted with four semi-empirical equations. Thermodynamic functions of activation of the binary systems were calculated according to the absolute rate theory of Eyring. The results show that the excess molar volumes are negative in the temperature range studied for all binary mixtures, and the deviation increases when temperature increases. Viscosity deviations （△η） are negative for FA-ethanol and FA-ethyl acetate binary mixtures, and the deviation increases when temperature decreases. For the binary systems of FA-propanol and FA-isopropanol, viscosity deviations （△η） show an＇S＇ shape, and the deviation change from negative to positive in low FA concentrations, which increases when temperature decreases. The three-body McAllister model is the best correlation to represent the viscosities of all binary mixtures, and the average relative errors between predicted and experimental data were minimum. The results indicate that activation enthalpy plays a major role in mixing processes.