Apparent specific volume and apparent specific refraction of some poly(oxyethylene) glycols in 1,4-dioxane and benzene solutions at 298.15 K

摘要

The density and refractive index of 1,4-dioxane and benzene solutions of poly(oxyethylene) glycols of the type HO-(CH2CH2O)(n)-H (n varying from 4 to 36) were measured at 298.15 K. From the experimental data the apparent specific volume and the apparent specific refraction at infinite dilution were calculated. The limiting apparent specific volume and the limiting apparent specific refraction were found to be inversely proportional to the number average molecular weight of solute. From the limiting apparent specific values at the infinite degree of polymerization, the partial molar volume and partial molar refraction of the monomeric unit were calculated. The partial molar volume as well as the partial molar refraction of the investigated compounds at infinite dilution are additive and depend linearly on the number of oxyethylene groups. The volumetric data were analyzed in terms of the intrinsic volume of solute molecules and by a void partial molar volume. The packing density of the investigated compounds approaches a uniform value as the size of the molecules increases and in both solvents limiting values are reached.