Concentration Dependence of Rheological Properties of Telechelic Associative Polymer Solutions

TL;DR

This study investigates how the concentration of associative telechelic polymers affects their rheological properties, revealing two regimes with distinct network structures and proposing models that explain both linear and nonlinear behaviors.

Contribution

The paper introduces single chain transient network models incorporating spatial correlations and network functionality to explain complex rheological phenomena in telechelic polymer solutions.

Findings

High concentration solutions form densely connected networks.

Low concentration solutions form sparsely connected networks.

Models reproduce shear thickening and thinning behaviors.

Abstract

We consider concentration dependence of rheological properties of associative telechelic polymer solutions. Experimental results for model telechelic polymer solutions show rather strong concentration dependence of rheological properties. For solutions with relatively high concentrations, linear viscoelasticity deviates from the single Maxwell behavior. The concentration dependence of characteristic relaxation time and moduli is different in high and low concentration cases. These results suggest that there are two different concentration regimes. We expect that densely connected (well percolated) networks are formed in high-concentration solutions, whereas sparsely connected (weakly percolated) networks are formed in low-concentration solutions. We propose single chain type transient network models to explain experimental results. Our models incorporate the spatial correlation effect of micellar cores and average number of elastically active chains per micellar core (the network functionality). Our models can reproduce non-single Maxwellian relaxation and nonlinear rheological behavior such as the shear thickening and thinning. They are qualitatively consistent with experimental results. In our models, the linear rheological behavior is mainly attributable to the difference of network structures (functionalities). The nonlinear rheological behavior is attributable to the nonlinear flow rate dependence of the spatial correlation of micellar core positions.