Shear effects on the phase separation behaviour of a polymer blend in solution by small angle neutron scattering

The phase separation behaviour of polystyrene and polybutadiene in dioctyl phthalate has been examined as a function of shear rate by small angle neutron scattering. A couette geometry shear cell was used to apply a shear field to the solution at various temperatures. Differences in the correlation lengths parallel and perpendicular to the flow direction were observed by assuming mean field behaviour of the solution. Dramatic decreases in the spinodal temperature were observed as a function of shear rate in the direction of flow. The results are consistent with the notion of shear stabilization and decoupling of the flow field in orthogonal directions.