The thermodynamic properties of solutions of polystyrene and of low molecular weight model compounds

Abstract

AbstractBinary mixtures of polystyrene, two low molecular weight model compounds, ethyl‐benzene and 1,3‐diphenylbutane, and benzene have been studied. The mixing parameters of these systems have been determined by calorimetry, pyenometry, and osmometry, and by measurement of vapor pressures and degrees of swelling. The results correspond qualitatively to predictions from the cell theory and from theories based on the theorem of corresponding states. The enthalpy, entropy, and volume of mixing are more negative in the homologous series for a greater difference in the molecular sizes of the components; the free enthalpy of mixing, however, becomes less negative and thus the x parameter increases. Several equations, useful in evaluating the mixing parameters according to the new Flory et al.11,12 theory have been derived. The values of the interaction parameter x12 have been calculated by means of these, and it has been found that the theory represents the measured data semiquantitatively.