Time-resolved small-angle neutron scattering investigation of induced demixing of a polymer blend under large-amplitude oscillatory shear

Shear-induced demixing of a binary blend of long- and short-chain polystyrenes has been investigated by time-resolved small-angle neutron scattering (SANS). A rotatable sliding-plate shear cell is employed to reconstruct the full three-dimensional anisotropic structures under shear from the measured two-dimensional SANS spectra on different planes. Quantitative analysis by the spherical harmonic expansion technique reveals an increase of zero-angle scattering as well as a symmetry inversion of anisotropic scattering associated with shear-induced demixing. Additionally, the degree of demixing is in phase with the applied strain under our experimental condition. A qualitative comparison of the experimental data with the hydrodynamic theory will also be discussed in this talk.