INVESTIGATION OF THE PHASE-BEHAVIOR IN A COMPRESSIBLE POLYMER-SOLVENTSYSTEM USING THE FULL TOMPA MODEL

Critical lines and the phase behavior of a compressible polymer-solven t system are investigated using of the full Tompa model for varying nu mbers of segments in each polymer chain. Critical lines are displayed in the density-density and the combined P,T and T,x planes for the ''r ight corner'' and also ''left corner'' cases. The crossing point, in a point at which two critical lines meet and exchange branches, is also calculated analytically. The P,T diagrams are discussed using the Sco tt and van Konynenburg phase diagram classifications. It is found that the right corner case corresponds to the transition from type II to t ype III classifications. On the other hand, the left corner case does not correspond to any of the six main phase diagram classes. (C) 1998 American Institute of Physics.