Viscoelastic properties of aqueous guar gum derivative solutions under large amplitude oscillatory shear (LAOS)

Daniel Szopinski; Gerrit A Luinstra

doi:10.1016/j.carbpol.2016.07.095

Viscoelastic properties of aqueous guar gum derivative solutions under large amplitude oscillatory shear (LAOS)

Carbohydr Polym. 2016 Nov 20:153:312-319. doi: 10.1016/j.carbpol.2016.07.095. Epub 2016 Jul 22.

Authors

Daniel Szopinski¹, Gerrit A Luinstra²

Affiliations

¹ Institute for Technical and Macromolecular Chemistry, University of Hamburg, Bundesstraße 45, 20146 Hamburg, Germany.
² Institute for Technical and Macromolecular Chemistry, University of Hamburg, Bundesstraße 45, 20146 Hamburg, Germany. Electronic address: luinstra@chemie.uni-hamburg.de.

PMID: 27561501
DOI: 10.1016/j.carbpol.2016.07.095

Abstract

The industrial relevant nonlinear viscoelastic properties of aqueous carboxymethyl hydroxypropyl guar gum (CMHPG) and non-ionic hydroxypropyl guar gum (HPG) solutions between semi-dilute and concentrated solution state were investigated by large amplitude oscillatory shear flow (LAOS). Aqueous CMHPG and HPG solutions enter the nonlinear flow regime at deformations γ0>100%. The nonlinear stress waveforms were analyzed by FT-rheology and orthogonal stress decomposition along the MITlaos framework. A rheological fingerprint is generated (Pipkin space) showing that the guar gum derivative solutions undergo a shear-thinning at high strains, which is preceded by a thickening above a minimum strain rate at intermediate strains. The influence and breakup of superstructures/aggregates gives a "rheological fingerprint", a function of the applied deformation and time scale (Pipkin space). A characteristic process time was found that scales exponentially with the overlap parameter with an exponent of 4/2, and is proposed to represent the relaxation process of the superstructure in solution.

Keywords: FT rheology; Guar gum derivatives; Hyperentanglement; Large amplitude oscillatory shear (LAOS); Stress decomposition.