Phase Equilibrium Compositions, Densities, and Viscosities of Aqueous Two-Phase Poly(ethylene glycol) + Poly(acrylic acid) System at Various Temperatures

Abstract

The effect of temperature on the densities and viscosities of aqueous solution of poly(acrylic acid) (PAA) of different mass fraction (from 0.05 to 0.50) and liquid−liquid equilibrium, densities, and viscosities for the aqueous two-phase PEG-6000 + PAA + water system at equilibrium have been measured. The densities and viscosities of the PAA + water system at different temperatures were correlated as a function of mass fraction. The binodal curves for the PEG + PAA + water system have been correlated using a four-parameter equation. The increase in temperature results in an increase in the two-phase region. The tie line compositions have been fitted to both the Othmer−Tobias and the Bancroft equations. A linear dependency of both the plots indicates the consistency of the data; however, the Bancroft equation gives the best fit.