Melt viscosities of lattice polymers using a Kramers potential treatment

Abstract

Kramers relaxation times $τ_{K}$ and relaxation times $τ_{R}$ and $τ_{G}$ for the end-to-end distances and for center of mass diffusion are calculated for dense systems of athermal lattice chains. $τ_{K}$ is defined from the response of the radius of gyration to a Kramers potential which approximately describes the effect of a stationary shear flow. It is shown that within an intermediate range of chain lengths N the relaxation times $τ_{R}$ and $τ_{K}$ exhibit the same scaling with N, suggesting that N-dependent melt-viscosities for non-entangled chains can be obtained from the Kramers equilibrium concept.