Rotation Diffusion as an Additional Mechanism of Energy Dissipation in Polymer Melts

TL;DR

This paper investigates how rotation diffusion contributes to energy dissipation in polymer melts, refining the reptation model to better match experimental viscosity exponents by including chain end motions.

Contribution

It introduces rotation vibration precession motion of chain ends into the reptation model, improving the theoretical prediction of melt viscosity exponents.

Findings

Predicted viscosity exponent of 3.4 aligns with experimental data.

Rotation diffusion significantly affects energy dissipation in polymer melts.

Enhanced model explains deviations from classical reptation predictions.

Abstract

The research is important for a molecular theory of liquid and has a wide interest as an example solving the problem when dynamic parameters of systems can be indirectly connected with their equilibrium properties. In frameworks of the reptation model the power law with the 3.4-exponent for the melt viscosity relation to the molecular weight of linear flexible-chain polymer is predicted as distinct from the value 3 expected for a melt of ring macromolecules. To find the exponent close to experimental values it should be taken into account the rotation vibration precession motion of chain ends about the polymer melt flow direction.