Liquid–liquid equilibria in ternary systems of linear and cross-linked water-soluble polymers (original) (raw)
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Colloid & Polymer Science, 1993
Flory Huggins theory modified by Pouchly has been applied to predict maxima and minima in the curve of total sorption in ternary polymer systems formed by a polymer and two liquids. In this work, different diagrams based on experimental magnitudes easily obtained such as the difference in affinities of liquids, solvents and non solvents, and the solvent molar volume ratio. Total sorption parameter has been considered to be the decisive magnitude to define extrema conditions in both cosolvent and cononsolvent ternary polymer systems. The theoretical prediction is not altered by the inclusion of ternary interactions. Different examples of ternary systems dealing with vinyl polymers and polydimethyl siloxane have been used to test the above formalism.
Colloid & Polymer Science, 1993
Flory-Huggins theory of polymer solutions has been used to express the condition of extrema values in the total sorption, as well as the inversion point in the preferential adsorption parameters for ternary polymer systems. Two approaches have been followed, the first considers the binary and ternary interaction parameters independent of polymer concentration and solvent composition. In the second one, this dependence has been introduced. Our attention is focused on the volume fraction of solvent mixture dependence of the above parameters, in order to confirm or not the coincidence between the extrema values and the inversion point. Several cosolvent and cononsolvent ternary polymer systems, have been used to test the validity of the equations obtained. Also, it has been verified, from an experimental point of view, that in cosolvent ternary polymer systems there is coincidence in both compositions while in cononsolvent ternary polymer systems, such coincidence does not appear.
Colloid and Polymer Science, 1993
Sorption equilibrium of polystyrene and poly (dimethyl siloxane) in mixed solvents has been monitored by means of the preferential adsorption coefficient experimentally determined from intensity light scattering measurements. The pairs of solvents used to dissolve each polymer sample have been selected for the purpose to perform cosolvent and cononsolvent ternary polymer systems. Flory-Huggins formalism including ternary interactions has been used to predict the sorption equilibrium for the cosolvent system and, for the first time, for cononsolvent ones. Moreover, the proportionality between binary and ternary interactions, recognized by Pouchly, is also corroborated for both ternary polymer systems. From a thermodynamic standpoint, the sorption equilibrium has been described by approaching the behavior of the "bulk solvent" to the binary liquid mixture through the excess Gibbs free energy.
Modelling the sorption of water–ethanol mixtures in cross-linked ionic and neutral polymers
Chemical Engineering Science, 2002
Water–ethanol sorption in strong sulfonated polystyrene cation-exchangers, in weak acrylic cation-exchangers and in neutral cross-linked dextran gels as well as their elastic properties have been measured. The effect of polymer matrix and cross-link density have been studied. The ionic resins were mainly in the Na+ form. The data have been analyzed by means of thermodynamic mixing models based on the
Polymer, 1986
Second virial (A2) and preferential solvation (2) coefficients, as well as binary interaction potentials (912), as measured by light scattering, for the ternary systems n-dodecane/butanone (MEK)/poly(dimethylsiloxane) (PDMS) and n-hexadecane/MEK/PDMS have been determined at 20.0°C. An inversion of 2 and a maximum in coefficient A2, at ¢1o-~0.57 in the n-dodecane/MEK/PDMS system and at q~o~0.40 in the nhexadecane/MEK/PDMS system, take place, both systems displaying cosolvent character. The coincidence in solvent composition at which A2 is maximum and 2=0 can, in light of the Flory-Huggins-Pouchl~ formalism, be used to predict the total sorption parameter Y from experimental ;t values and vice versa. The developed formalism is proven to hold for the above ternary systems as well as for n-nonane/MEK/PDMS, ndecane/MEK/PDMS and n-undecane/MEK/PDMS.
Measurement and correlation of vapor sorption equilibria of polymer solutions
Fluid Phase Equilibria, 1998
Solvent sorption equilibrium data of binary solventrpolymer systems were measured using a vacuum electromicrobalance. Solvents tested were benzene, cyclohexane, n-hexane, water and methanol. Rubbery Ž. Ž. Ž. polymers tested were poly dimethylsiloxane, PDMS , poly iso-butylene, PIB , poly propylene oxide, PPO and Ž. poly vinyl alcohol, PVA. Data obtained in the present study, together with existing literature data, were Ž E. Ž. correlated by both the UNIQUAC, Gibbs function g-model and a recent volumetric EOS equation of state proposed by the present authors based on a non-random lattice-hole theory.
Viscometric and sorption equilibrium studies on n-alkane-butanone-poly-(dimethylsiloxane) systems
European Polymer Journal, 1984
Abstrac~lntrinsic viscosities, [~], second virial coefficients, A 2, and preferential solvation coefficients. 2, for the ternary systems n-alkane (l)-butanone (2)-poly(dimethylsiloxane) (PDMS) (3), with n-alkane-nhexane, n-heptane, n-nonane and n-undecane, have been determined at 20'. The K and a constants of the Mark-Houwink equation have been evaluated over the whole composition range of the binary solvent mixtures. Polymer (mixed solvent) interaction parameters and unperturbed dimensions have been evaluated both from A 2 and [r/] data, the feasibility of A 2 evaluation from [~/] experimental data or vice versa being discussed. Experimental and calculated (through Dondos and Patterson theory) excess free energies, G E, follow similar trends with composition; large numerical discrepancies, however, arise between both sets of G E. Maxima in It/], in a and in A 2 are accompanied by inversion points in 2. The solvent mixture composition range in which PDMS is preferentially solvated by n-alkane, as well as the extent of solvation, decrease with increasing number of carbon atoms in the n-alkane.
Korean Journal of Chemical Engineering, 1998
Solvent sorption equilibrium data of binary solvent-polymer systems were measured with a vacuum electro-microbalance equilibrium cell. Tested solvents were benzene, n-pentane, cyclohexane, n-hexane, water and methanol. Polymers tested were poly(dimethylsiloxane), poly(iso-butylene), poly(propylene oxide) and poly(vinyl alcohol). Data obtained in the present study, together with existing literature data, were correlated by two ge_ models, such ms UNIQUAC and the Flory-Huggins model, and four equations of state which stem from the lattice fluid theory, such as models proposed by Flory, Sanchez and Lacombe, Panayiotou and Vera, and the NLF model proposed recently by the present authors. For each solvent-polymer system, the provided models give a quantitative correlation. The advantages and drawbacks of the ge-model and equation of state approaches are also discussed.