Effect of oscillatory shear on polymer solutions.
We consider the effects of oscillatory shear flow on small concentration fluctuations in polymer solutions, which we model as highly asymmetric entangled polymer blends. A simple model that enables us to predict the scattering patterns in the flow-vorticity plane is presented. It is shown that peaks in the patterns occur in the flow direction at a finite wave vector, their position strongly depends on the angular frequency of oscillatory shear flow, whereas the intensity of these peaks is rather controlled by the amplitude of the flow. The model reproduces characteristic double-winged anisotropic scattering patterns called "butterfly," which are stable and thus represent concentration fluctuations rather than phase separation.
Miroshnychenko
Dmitri
D
Department of Chemistry, Science Laboratories, University of Durham, South Road, Durham DH1 3LE, United Kingdom.
Clarke
Nigel
N