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 shear rate) on the phase state was studied for three polymer systems : for the solutions of PS of different molecular masses in a cyclohexanone-toluene (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-mass PS, no effect of shear deformation on their phase state was observed. In all other cases, phase separation was shown to be assisted by the action of the mechanical field, and an increase in the temperature of amorphous separation may be as high as 30 K. However, at very high shear rates, this shift in phase transition temperatures tends to decrease, and in some cases, the compatibility may be even enhanced. Hence, depending on the magnitude of the applied shear stress (shear rates), the compatibility between the components of the same polymer solution can either decrease or improve.