Berlin 2015 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 64: Flow-Induced Structures in Complex Fluids (with DRG, Deutsche Rheologische Gesellschaft, and DY)
CPP 64.2: Vortrag
Donnerstag, 19. März 2015, 09:45–10:00, C 264
Linear and Nonlinear Rheological Behavior of Carboxymethyl Hydroxypropyl Guar Gum — •Daniel Szopinski1, Ulrich A. Handge2, Werner-Michael Kulicke1, Volker Abetz2,3, and Gerrit A. Luinstra1 — 1Institute of Technical and Macromolecular Chemistry, University of Hamburg, Hamburg, Germany — 2Institute of Polymer Research, Helmholtz-Zentrum Geesthacht, Geesthacht, Germany — 3Institute of Physical Chemistry, University of Hamburg, Hamburg, Germany
Guar gum is a natural non-ionic polysaccharide from the endosperm of the guar bean (cyamopsis tetragonoloba), which primarily grows in India and Pakistan. The water-thickening property is the main driver for its industrial application, which is resulting from the high molecular weight (1000-2000 kg/mol) and the formation of superstructures. Guar gum may be chemically modified with carboxymethyl (CM) and/or hydroxypropyl (HP) entities to enhance the thermal stability and solubility in water. A comprehensive rheological characterization of carboxymethyl hydroxypropyl guar gum (CMHPG) will be presented. Material functions were determined in experiments under steady state shear flow, small amplitude oscillatory shear flow (SAOS) and extensional flow (CaBER). The flow behavior at the application relevant nonlinear viscoelastic region was mapped in large amplitude oscillatory shear (LAOS) experiments. Structure-property relationships were established for dilute and more concentrated solutions as function of concentration and molecular weight. It is a basis for a description of the superstructures that guar gum and its derivatives form in water.