2003/06/07 by Sergej Stryuk, Stryuk, Sergej, Bernhard A. Wolf +2
Chemical Engineering · Chemistry · Engineering · Physics and Astronomy · #Chemical Thermodynamics and Molecular Structure #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Phase Equilibria and Thermodynamics #Soft Condensed Matter (cond-mat.soft) #Thermodynamic properties of mixtures #cond-mat.mtrl-sci #cond-mat.soft
paper · pdf · doi:10.48550/arxiv.cond-mat/0306195
arxiv created 2003/06/07 · openalex publication_date 2003/06/07 · arxiv updated 2009/11/30 · openalex created_date 2022/08/29 · openalex updated_date 2026/07/28
A simple expression for the composition dependence of the Flory-Huggins\ninteraction parameter of polymer/solvent systems reported earlier is used to\nmodel the demixing of polymer solutions into two liquid phases. To this end the\nsystem specific parameters zeta and ny of that approach are calculated as a\nfunction of temperature using the thermodynamic expressions resulting for the\ncritical conditions on one side and from experimentally determined critical\ndata for polymers of different molar mass on the other side. By means of data\nreported for the system cyclohexane/polystyrene it is demonstrated that binodal\nand spinodal lines are very accurately modeled at low temperatures (UCSTs) and\nat high temperatures (LCSTs). The parameters obtained from the demixing\nbehavior match well with that calculated from the composition dependence of the\nvapor pressure at temperatures where the components are completely miscible.\nInformation on the phase separation of the system trans-decalin/poly-styrene\nfor different molecular weights and at different elevated pressures is used to\nshow that the approach is also apt to model pressure influences. The thus\nobtained zeta (T;p) and ny (T;p) enable the prediction of the (endothermal)\ntheta temperature of the system as a function of pressure in quantitative\nagreement with the data directly obtained from light scattering measurements\nwith dilute solutions.\n