Phase Russia transitions in the PE-p-xylene system are studied under s
tatic conditions and in the flow regime. A qualitative change of the b
oundary-curve shape is found for the system with crystal phase separat
ion in a shear stressfield. For the polymer-solvent system under the a
pplied stress field, the concentration dependencies of the interaction
parameters of the components are calculated using the Flory-Huggins t
heory.