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  • Title: Rheology of a reversible supramolecular polymer studied by comparison of the effects of temperature and chain stoppers.
    Author: Knoben W, Besseling NA, Cohen Stuart MA.
    Journal: J Chem Phys; 2007 Jan 14; 126(2):024907. PubMed ID: 17228973.
    Abstract:
    The rheology of a reversible supramolecular polymer is studied by comparing the effects of an increase in temperature and the addition of chain stoppers. The dependence of the zero-shear viscosity and the terminal relaxation time on temperature is exponential, and the activation energy for viscous flow can be calculated. Above a critical stopper fraction, power laws describe the stopper dependence of the viscosity and relaxation time. A simple model for the effect of the addition of chain stoppers on the average degree of polymerization adequately describes the results. A comparison of flow curves at several temperatures and stopper fractions reveals considerable differences between solutions with the same zero-shear viscosity. These are mainly associated with differences in the terminal relaxation time. A mechanism of shear-induced alignment and subsequent elongation of chains is proposed, with which the experimental results are consistent.
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