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Thermodynamic analysis of phase equilibrium and surface tension of ternary polymer solutions
Author(s) -
Yang Han Earl,
Bae Young Chan
Publication year - 2019
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.16679
Subject(s) - surface tension , polymer , thermodynamics , ternary operation , vinyl alcohol , polystyrene , cyclohexane , surface energy , work (physics) , phase (matter) , materials science , ternary numeral system , gibbs isotherm , chemistry , organic chemistry , composite material , physics , computer science , programming language
The liquid–liquid equilibrium (LLE) and surface behavior of polymer solutions were investigated. Systems of poly vinyl methyl ether (PVME)/water and polystyrene (PS)/cyclohexane were chosen as model systems because they show different types of LLE and surface behavior. Ternary polymer solutions of PVME/water/alcohol and PS/cyclohexane/alcohol were also studied. The cloud points of given systems were determined by thermo‐optical analysis method. For surface tension measurements at the air/polymer solution interface, the well‐known plate method was utilized. The investigated polymer solutions exhibit various types of LLE and surface behavior depending on the type of solvent and temperature. The modified double lattice model with chain length dependence is used for description of the phase equilibrium. To improve the interpretation of the surface behavior of the polymer solution, we developed a new thermodynamic frame work based on density gradient theory. Thermodynamic analysis was also conducted using the proposed model to provide understanding of the surface behavior. The surface energy difference and interchange energy had an important role in the driving force of the surface behavior. Utilizing the predetermined model parameters from the phase equilibrium calculation, the proposed model provides satisfactory agreement with measured surface tension data, with less than 5% error.