Viscoelastic response of bidisperse melts in the lateral motion model

A model for stress relaxation of linear chain polymer melts in the linear viscoelastic regime is proposed. This model is developed in the context of the lateral motion model of polymer dynamics, which assumes that polymers diffuse in the melt by sliding laterally along the curvilinear contours of neighboring chains. It is assumed that, in the post‐plateau region of the time dependent stress relaxation, the stress is supported by interchain contacts. When each contact breaks, a new contact is formed, since the number of interchain contacts is an equilibrium property. It is also assumed in this model that the new contacts, formed after the application of the strain, support partial stress because the polymer system is not isotropic at the time of the formation of these new contacts. The stress relaxation is evaluated within this model for monodisperse and bidisperse melts using a computer simulation procedure. The results are compared with published experimental data. Very good agreement is found with the e...