Title: Dynamical structure of entangled polymers simulated under shear flow,
Abstract: The non-linear response of entangled polymers to shear flow is complicated.
Its current understanding is framed mainly as a rheological description in
terms of the complex viscosity. However, the full picture requires an
assessment of the dynamical structure of individual polymer chains which give
rise to the macroscopic observables. Here we shed new light on this problem,
using a computer simulation based on a blob model, extended to describe shear
flow in polymer melts and semi-dilute solutions. We examine the diffusion and
the intermediate scattering spectra during a steady shear flow. The relaxation
dynamics are found to speed up along the flow direction, but slow down along
the shear gradient direction. The third axis, vorticity, shows a slowdown at
the short scale of a tube, but reaches a net speedup at the large scale of the
chain radius of gyration.