Structures in a Semidilute Polymer Solution Induced under Steady Shear Flow As Studied by Small-Angle Light and Neutron Scattering

Abstract

Structures induced by a steady shear flow in a semidilute polymer solution of high molecular weight deuterated polystyrene in dioctyl phthalate are investigated. By a combined use of small-angle light scattering (SALS) and small-angle neutron scattering (SANS), we are able to obtain scattering functions of the shear-induced structures over 3 orders of magnitude in wavenumber (q) and 7 orders of magnitude in intensity. The changes in the structures with shear rate (γ) at a given temperature and with temperature at a given γ are explored. At a given temperature, the shear flow induces a structural change in the solution at γ larger than a critical shear rate γc, giving rise to a scattering pattern called “butterfly pattern” in the low q region of SANS, while keeping the same pattern as that in the quiescent state in the q region of SALS. As γ increases, the butterfly patterns evolved not only in the low q region of SANS but also in the q region of SALS. This indicates that the shear-induced structures ...