Characteristic Time and Length Scales in Melts of Kremer–Grest Bead–Spring Polymers with Wormlike Bending Stiffness
Carsten Svaneborg, Ralf Everaers
Abstract
The Kremer–Grest (KG) model is a standard for studying generic polymer properties. Here we have equilibrated KG melts up to and beyond 200 entanglements per chain for varying chain stiffness. We present methods for estimating the Kuhn length corrected for incompressibility effects, for estimating the entanglement length corrected for chain stiffness, and for estimating bead frictions and Kuhn times taking into account entanglement effects. These are the key parameters for enabling quantitative, accurate, and parameter free comparisons between theory, experiment, and simulations of KG polymer models with varying stiffness. We demonstrate this for the chain dynamics in moderately to highly entangled melts as well as for the shear relaxation modulus for unentangled melts, which are found to be in excellent agreement with the predictions from standard theories of polymer dynamics.