Correlation of solvent activities in polymer solutions: a comparison of models

Prediction of vapor–liquid and liquid–liquid equilibria for polymer systems: Comparison of activity coefficient models

“…The results are shown in Fig. 10, and its behavior can be translated as WAAD (%) = 0.0209C 2 − 0.2563C + 0.8182 (13) where C is the hydrocarbon solvent carbon number.…”

“…The activity of the polymer is a predominant factor in LLE (liquid-liquid equilibrium) calculations for polymer solutions. A large number of equations of state and activity coefficient models capable of describing phase equilibrium in polymer solutions are available today, but only a few of these models have been tested for several different systems [9,12,13]. The studies in the literature normally focus on the residual contribution for a fixed free-volume contribution [14,15].…”

Classical and recent free-volume models for polymer solutions: A comparative evaluation

“…The case of the paints and coatings industry can be mentioned as a typical example. UNIFAC-based models which are successful for polymers account for the free-volume differences between polymers and solvents and numerous such models have been presented in the literature [3][4][5][6][7][8][9][10][11][12][13][14]. In these models, typically the UNIFAC energetic parameters of the residual term are not reestimated using the new combinatorial/FV terms; thus original UNIFAC parameter tables are used.…”

“…The first model in the family of UNIFAC-based free-volume models is the UNIFAC-FV proposed by Oishi and Prausnitz [4], which successfully predicts solvent activities in many non-aqueous polymer solutions, but the results are less satisfactory for aqueous solutions, longchain solute activities and LLE. The shortcomings for aqueous solutions are due to the fact that free-volume expression in UNIFAC-FV is always an additive term with a positive effect, while water has a lower free-volume percentage than most polymers [9]. Kannan et al [5] have recently developed, based on the generalized van der Waals partition function, a new FV term coupled to UNIFAC in an attempt to solve this problem.…”

New local composition model for polymer solutions

“…Among these local composition models, only the UNIQUAC model [5] can be used for the modeling of the phase equilibrium of polymer solutions (which involve molecules with very different structure) without further modification, because the UNIQUAC model accounts for molecular size and shape through the volume and surface area parameters. Recently, Pedrosa et al [10] developed a segment-based UNIQUAC model that uses a combination of combinatorial term (represented by the entropic free volume, p-free volume and Freed Flory-Huggins equation) and the segment-based UNIQUAC model for residual term. The UNIFAC model [6] was extended to polymer solutions by Oishi and Prausnitz [11].…”