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Effects of Pressure and Molecular Weight on the Miscibility of Polystyrene and Cyclohexane
Author(s) -
Sun Zhaoyan,
An Lijia,
Li Hongfei,
Jiang Zhenhua,
Wu Zhongwen
Publication year - 2001
Publication title -
macromolecular theory and simulations
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 56
eISSN - 1521-3919
pISSN - 1022-1344
DOI - 10.1002/1521-3919(20010901)10:7<692::aid-mats692>3.0.co;2-u
Subject(s) - miscibility , cyclohexane , polystyrene , polymer chemistry , materials science , molar mass distribution , polymer science , thermodynamics , chemistry , organic chemistry , polymer , physics
With the aid of Sanchez‐Lacombe lattice fluid theory (SLLFT), the phase diagrams were calculated for the system cyclohexane (CH)/polystyrene (PS) with different molecular weights at different pressures. The experimental data is in reasonable agreement with SLLFT calculations. The total Gibbs interaction energy, g * 12 , for different molecular weights PS at different pressures was expressed, by means of a universal relationship, as g * 12 = f * 12 + ( P – P 0 ) υ * 12 . P ‐ T demixing curves were then calculated at fixed (near critical) compositions of CH and PS systems for different molecular weights. The pressures of optimum miscibility obtained from the Gibbs interaction energy are close to those measured by Wolf and co‐workers. Furthermore, a reasonable explanation was given for the earlier observation of Saeki et al., i. e., the phase separation temperatures of the present system increase with the increase of pressure for the low molecular weight of the polymer whereas they decrease for the higher molecular weight polymers. The effects of molecular weight, pressure, temperature and composition on the Flory‐Huggins interaction parameter can be described by a general equation resulting from fitting the interaction parameters by means of Sanchez‐Lacombe lattice fluid theory.