POLYMER-SOLUTIONS WITH SPECIFIC INTERACTIONS - CHI-PARAMETER FOR POLY(4-HYDROXYSTYRENE) + ACETONE

The vapor pressure of poly(4-hydroxystyrene) + acetone has been measured at six temperatures between 298.15 and 318.15 K and for 0.35 less-than-or-equal-to w1 less-than-or-equal-to 0.89, w1 being the weight fraction of acetone. The Flory-Huggins chi-parameter has been calculated and found to increase with increasing w1. A thermodynamic consistency test has been developed, and the data have been found to satisfy it. The local composition in the mixture has been discussed in terms of the Kirkwood-Buff-Zimm integrals and found to differ significantly from the bulk composition. Finally, a rigid-lattice model that incorporates the local composition concept has been tested. Differences between predicted and experimental results are larger than the uncertainty of the measurements.