Shear-induced mixing and demixing in aqueous methyl hydroxypropyl cellulose solutions.

The influence of shear flow on the phase separation of aqueous methyl hydroxypropyl cellulose solutions was investigated by means of rheoturbidity and online rheo small angle light scattering (SALS) experiments. In semidilute solution shear-induced mixing was observed and the cloud curve was shifted to higher temperatures with increasing shear rate. With higher concentrated solutions, however, shear-induced demixing was found. The shear-induced mixing is interpreted as being a disruption of slightly entangled clusters under the influence of the shear energy. The shear demixing appears in line with the observation with other systems. A characteristic butterfly pattern was observed in rheo-SALS.