Shear induced mixing/demixing: Blends of homopolymers, of homopolymers plus copolymers, and blends in solution

Shear may shift the phase boundary towards the homogeneous state (shear induced mixing, SIM), or in the opposite direction (shear induced demixing, SID). SIM is the typical behavior of mixtures of components of low molar mass and polymer solutions, SID can be observed with solutions of high molar mass polymers and polymer blends at higher shear rates. The typical sequence with increasing shear rate is SIM, then occurrence of an isolated additional immiscible area (SLD), melting of this island into the main miscibility gap, and finally SIM again. A three phase line originates and ends in two critical end points. Raising pressure increases the shear effects. For copolymer containing systems SID is sometimes observed at very low shear rates, preceding the just mentioned sequence of shear influences.