Phase equilibria in the two‐phase system polystyrene—liquid sulphur dioxide

Abstract

The concentration and molecular weight distribution (GPC) of polystyrene (PS) in the two phases of the PS‐SO2 (δ)‐system were determined. Typical concentrations of PS in the upper phase were around 30%, while the lower phase contained at most 1% PS. An exception was a PS‐grade with a low molecular weight (MW 3.5 · 103), which dissolved homogeneously. The molecular weight of PS in the lower phase was substantially below an the one found in the concentrated phase. Mechanical agitation was necessary to attain an equilibrium state; during the equilibration the upper phase became more diluted. At the same time the molecular weight of the lower phase PS‐fraction increased, while the MW value in the upper phase remained practically unchanged and equal to that of the virgin sample. The fractionation with regard to the molecular weight between the two phases was also reflected in the Tg‐values of the fractions. The value of X(Flory‐Huggins parameter) determined from vapour pressure data above the concentrated phase was 0.8–1.

Treatment of poly(styrene‐co‐methacrylic acid)/poly(4‐vinylpyridine) blends in solution under liquid–liquid phase‐separation conditions. A new method for phase‐separation data attainment from viscosity measurements

“…These groups increase polymer compatibility in organic solution; usually these groups induce the formation of hydrogen bonding interactions 15, 18–20. In most works devoted to the study of mixtures of polymers in solution, Gibbs ternary phase diagrams were represented, which sometimes were built with vitreous transition temperatures21 and, some other times, binodal equilibrium curves of different polymer mixtures were approximated by cloud‐point isotherms7–9, 15, 22 or under liquid–liquid phase‐separation conditions.…”