H.-M. Petri, R. Horst and B. A. Wolf
"Determination of interaction parameters for highly incompatible polymers"
Polymer 1996, 37, 2709-2713.
Abstract: Experiments and calculations were performed for the ternary system cyclohexane/polystyrene/polyisobutylene (CH/PS/PIB) to study the possibilities of determining the Flory-Huggins interaction parameters chi(PS/PIB) between these highly incompatible polymers. To that end chi(CH/PIB) was determined (vapour pressure measurements and additional thermodynamic information) as a function of composition; chi(CH/PS) and its concentration dependence could be taken from earlier experiments. Furthermore, the cloud point curve and some tie lines of the ternary system were measured. In the subsequent evaluation of these data, the phase diagram was calculated and chi(PS/PIB) (as a function of concentration) adjusted until the theoretically calculated binodal line matches with the measured cloud points. The polymer/polymer interaction parameter thus obtained increases at 35 degrees C from 0.416 in the limit of pure PS to 0.449 in the limit of pure PIE. This result agrees reasonably well with the prediction of the solubility parameter theory and is in good accord with information stemming from light scattering experiments in a ternary system under 'optical theta conditions'.

preprint number: 166