Solid−Liquid−Liquid Equilibria in Polymer Solutions

Abstract

The thermodynamics of solid-liquid equilibrium is applied to binary systems including a semicrystalline polymer and a solvent. Group-contribution activity coefficient models are used for describing the nonideal behavior of the liquid phase. The solid polymer properties are obtained via group-contribution methods and tested for consistency. Methods for the simultaneous solution of the solid-liquid and liquid-liquid equilibrium are presented. The full phase envelope of polymer solutions can be predicted, and the use of the empirical solubility parameter approach is avoided. The effects of polymer semicrystallinity and molecular weight on the solidliquid equilibria are displayed, and a comparison of our predictions with experimental data is performed.

Surface tension, (solid+liquid) equilibria and (liquid+liquid) equilibria for (iPBu-1+hydrocarbon, or alcohol) systems

“…6). From the literature it is known that for (PE, PP or PIB + alcohols) systems, the large miscibility gaps are observed at low mole fraction of polymer [28]. The upper critical solution temperature, UCST, and composition was possible to obtain experimentally only for one system: {iPBu-1 (18 708 Da) + 2-butanol} (T c = 361.4 K for x c = 0.0004).…”

SAFT Modeling of the Effect of Various Carriers on the Operating Range of Slurry Reactors

“…Calculations using the same approximations for the solid phase have also been reported by others. 3,[15][16][17] For a qualitative discussion on SLE in polymer systems refer to work by Richards. 18 For SLE of a crystalline solute in a solvent, the fugacities of the solute in the solid phase (S) and liquid phase (L) are equal:…”

“…The predominant solid model used is one in which the solid phase is a pure crystalline phase as discussed by Prausnitz et al A variant for the case of multicomponent phase equilibria is when the solid phase is a solid solution; in this case the solid solution is often assumed to be ideal. The liquid phase, on the other hand, has been modeled by a variety of models ranging from the ideal solution model (which works very well for a number of systems including n -alkanes with chain length less than 20) to activity coefficient models to statistical mechanics based models such as SAFT, which is a commonly used equation of state for modeling liquid phases containing polymers and other complex chain molecules.…”

Ternary Solid–Liquid Equilibria of Semicrystalline, Branched Polymer Solvent Mixtures—A Theoretical Study by Means of Lattice Cluster Theory

“…Such studies extend back over more than 5 decades. − The applied approaches can be divided in two groups. The first one focuses on the description of the nonideality of the liquid phase in equilibrium with the solid phase, where equation of states (e.g., ref ) or models for the activity coefficients (e.g., ref ) were used. For instance, Harismiadis et al calculated the SLE for a binary system including a semicrystalline polymer and a solvent by means of a group contribution method, for which the degree of crystallinity is taken into account, but not the degree of branching.…”

“…The first one focuses on the description of the nonideality of the liquid phase in equilibrium with the solid phase, where equation of states (e.g., ref ) or models for the activity coefficients (e.g., ref ) were used. For instance, Harismiadis et al calculated the SLE for a binary system including a semicrystalline polymer and a solvent by means of a group contribution method, for which the degree of crystallinity is taken into account, but not the degree of branching. The second approach focuses on the special properties of the solid phase; however, the nonideality of the liquid phase is neglected .…”