PRESSURE-VOLUME TEMPERATURE BEHAVIOR OF MOLTEN POLYMERS - SOLUBILITY PARAMETERS IN THE VIEW OF PRIGOGINE-FLORY AND SANCHEZ-LACOMBE EOS-THEORIES

The solubility parameter theory of Hildebrand and Scott extended for p olymer blends originally has accounted for dissimilarities only betwee n contact energies of the blend components, neglecting free volume eff ects which are predicted by the corresponding states theories. Biros e t al., however, have shown that using expressions of the Prigogine-Flo ry corresponding state theories for energy and volume, effects of free volume will be implicitly included in the solubility parameter approa ch too. The results are similar then to those derived by the correspon ding state theories. In addition, it is shown that in this case the te mperature and pressure dependencies of the solubility parameters are p redicted qualitatively correct. We performed this procedure with the S anchez-Lacombe EOS theory instead of the Prigogine-Flory approach. For mally, identical expressions result, and the calculated solubility par ameters evaluated according to the two EOS theories are in good agreem ent. However, because Sanchez-Lacombe's approach is not a correspondin g state theory, it is able to predict additionally qualitatively corre ct the dependence of the solubility parameters on chain length.