PHASE-SEPARATION IN SOLUTIONS OF FLEXIBLE -CHAIN POLYMERS UNDER THE ACTION OF SHEAR DEFORMATION

The effect of shear deformation (in a wide range of variations in shea r rate) on the phase state was studied for three polymer systems: for the solutions of PS of different molecular masses in a cyclohexanone/t oluene (58:42) mixture, for the solutions of PB in a toluene/ethanol ( 70:30) mixture, and for PVA in ethanol. In the case of low-molecular-m ass PS, no effect of shear deformation on their phase state was observ ed. In all other cases, phase separation was shown to be assisted by t he action of mechanical field, and an increase in the temperature-of a morphous separation may be as high as 30 K. However, at high shear rat es, this shift in phase transition temperatures tends to decrease, and in some cases, even the compatibility may be even enhanced. Hence, de pending on the magnitude of the applied shear stress (shear rates), th e compatibility between the components of the same polymer solution ca n either decrease or improve.