Abstract
The precipitation temperature for each volume fraction of polystyrene in cyclohexane tested increased with increasing pressure. The Flory theta temperature increases almost 1° K for a pressure increase of 200 atmospheres. The entropy parameter psi is only slightly dependent upon the pressure, if at all; however, this is contingent upon the hypothesis that the product of theta and psi is a constant independent of pressure. The inclusion of a X (subscript 2Ø3) for a solvent helps to broaden the theoretical curve of the interaction parameter x� versus the volume fraction of polymer Ø, for certain values of X ₂, so that there is better agreement between the theoretical curves and the experimental curves. A value of x₂ = 1/9 brings about a better agreement between the theoretical and the experimental curves for a weight-average molecular weight of 82,000 for polystyrene in cyclohexane. A slightly larger value than 1/9 for x₂ may bring an even better agreement. A value of x₂ = 1/18 seems to be the value for x₂ for the weight-average molecular weight of 267,000. These values contradict those suggested by Orofino and Flory. Another problem is that as x₂ increases in size, the critical value for x� decreases below that found by experiment.
Bolen, Max C. (1961). Phase equilibria studies of polystyrene and cyclohexane solutions at various pressures. Doctoral dissertation, Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -171498.