Spatial Dependence of Molecular Relaxation in Deformed Polymers

A general framework for investigating the spatial and temporal dependence of structural anisotropy relaxation in deformed polymers is presented. Small-angle neutron scatteringexperiments on polymer melts over a wide range of molecular weights reveal that their conformational relaxation at relatively high momentum transfer$Q$ and short time can be described by a simple scaling law, with the relaxation rate proportional to $Q$. This scaling behavior, while further confirmed by non-equilibrium molecular dynamics simulations, does not conform with either the Rouse or reptative motions depicted in the classical models.