Dynamics of Polymer Molecules in Dilute Solution: Viscoelasticity, Flow Birefringence and Dielectric Loss

TLDR

The study examines the motion of a polymer chain diffusing in a viscous fluid under external forces or currents. The authors model the chain as beads linked by ideal springs, incorporate Kirkwood–Riseman hydrodynamic interactions, and solve the dynamics exactly via a normal‑coordinate transformation. They compute viscosity, flow birefringence, dielectric, and tensile relaxation, finding intrinsic viscosity differs from Kirkwood–Riseman, remains shear‑rate independent, and that the relaxation‑time spectrum peaks at a lower frequency than in previous Rouse or Kuhn–Kuhn/Kirkwood–Fuoss analyses.

Abstract

The problem of the motions of a chain molecule diffusing in a viscous fluid under the influence of external forces or currents is considered for a particular model. This model is a chain of beads connected by ideal springs. Hydrodynamic interaction between the beads is introduced in the approximate form due to Kirkwood and Riseman. It is possible to solve this problem exactly with the use of a transformation to a set of normal coordinates. The viscosity, birefringence of flow, and dielectric and tensile relaxation behavior are calculated explicitly. The intrinsic viscosity in steady flow is somewhat different from the Kirkwood-Riseman result, and there is no change of viscosity with shear rate. The spectrum of relaxation times is similar to that found by Rouse and by F. Bueche, but has its maximum at a lower frequency than those obtained by Kuhn and Kuhn and by Kirkwood and Fuoss in other ways.