Free Volume, Cohesive Energy Density, and Internal Pressure as Predictors of Polymer Miscibility

Over half a century ago, Wiehe and Bagley suggested that a product of the internal pressure and molar volume of a liquid measures the energy of nonspecific intermolecular interactions whereas the cohesive energy reflects the total energy of intermolecular interactions in the liquid. This conjecture, however, has never been considered in connection with near and supercritical fluids. In this contribution, the cohesive energy density, internal pressure and their ratios are calculated from high precision equations of state for eight important fluids including water. To secure conformity to the principle of corresponding states when comparing different fluids, the calculations are carried out along the line defined by equality between the reduced temperature and the reduced pressure of the fluid (Tr = Pr). The results provide additional illustration of the tunability of the solvent properties of water that stands apart from those of other near and supercritical fluids in common use. In addition, an overview is also presented of the derivatives of cohesive energy density, solubility parameter and internal pressure with respect to temperature, pressure and molar volume.

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Solvent structure. The use of internal pressure and cohesive energy density to examine contributions to solvent-solvent interactions

Australian Journal of Chemistry ◽

10.1071/ch9751643 ◽

1975 ◽

Vol 28 (8) ◽

pp. 1643 ◽

Cited By ~ 76

Author(s):

MRJ Dack

Keyword(s):

Energy Density ◽

Internal Pressure ◽

Cohesive Energy ◽

Polar Solvent ◽

Polar Solvents ◽

Solvent Interactions ◽

Cohesive Energy Density ◽

Hexamethyl Phosphoramide ◽

Internal Pressures ◽

Solvent Solvent

Internal pressures, (∂U/∂V)T, have been obtained at 25� for the solvents dimethyl sulphoxide, propylene carbonate, formamide, dimethylformamide, acetonitrile, methanol and hexamethyl-phosphoramide by measurement of the thermal pressure coefficients. Data in the literature suggest that values of the internal pressure and the cohesive energy density, (ΔU/Vm), are similar for a non-polar solvent. The observed divergence of the two properties in the polar solvents under investigation is discussed in terms of the nature of the solvent-solvent interactions.

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Studies on the structure of [Bmim][NO3] and 1-alkanol: Cohesive energy density and internal pressure

Journal of Molecular Structure ◽

10.1016/j.molstruc.2020.128576 ◽

2020 ◽

Vol 1219 ◽

pp. 128576 ◽

Cited By ~ 2

Author(s):

Mohammad Almasi

Keyword(s):

Energy Density ◽

Internal Pressure ◽

Cohesive Energy ◽

Cohesive Energy Density

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Correlation between Cohesive Energy Density, Fractional Free Volume, and Gas Transport Properties of Poly(ethylene-co-vinyl acetate) Materials

International Journal of Polymer Science ◽

10.1155/2015/861979 ◽

2015 ◽

Vol 2015 ◽

pp. 1-8 ◽

Cited By ~ 7

Author(s):

Piotr Kubica ◽

Aleksandra Wolinska-Grabczyk

Keyword(s):

Energy Density ◽

Transport Properties ◽

Vinyl Acetate ◽

Free Volume ◽

Cohesive Energy ◽

Transport Model ◽

Preceding Paper ◽

Fractional Free Volume ◽

Cohesive Energy Density ◽

Poly Ethylene

The transport properties of the poly(ethylene-co-vinyl acetate) (EVA) materials to He, N2, O2, and CO2are correlated with two polymer molecular structure parameters, that is, cohesive energy density (CED) and fractional free volume (FFV), determined by the group contribution method. In our preceding paper, the attempt was made to approximate EVA permeability using a linear function of 1/FFV as predicted by the free volume theory. However, the deviations from this relationship appeared to be significant. In this paper, it is shown that permeation of gas molecules is controlled not only by free volume but also by the polymer cohesive energy. Moreover, the behavior of CO2was found to differ significantly from that of other gases. In this instance, the correlation is much better when diffusivity instead of permeability is taken into account in a modified transport model.

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