Aqueous polysaccharide blends based on hydroxypropyl guar gum and carboxymethyl cellulose: synergistic viscosity and thixotropic properties

Aqueous polysaccharide blends, formed from 2.5% (w/v) solution of hydroxypropyl guar gum (HPG) and 2.5% (w/v) solution of carboxymethyl cellulose (CMC) according to different blending ratios, were investigated at 20 degrees C in terms of their shear-dependent viscosity and thixotropic properties. The Cross viscosity equation was found to fit the shear-dependent viscosity data with reasonable accuracy. When the HPG solution with the mass fraction (f (HPG)) of 0.87 was mixed, the zero shear viscosity (eta (o)) of the corresponding blend was found to be 168.5753 Pa s, while the eta (o) values of component HPG and CMC solutions were found to be 3.3859 and 98.6525 Pa s, respectively. For the aqueous HPG/CMC blends investigated, the resulting zero shear viscosity was observed to be much greater than the combined zero shear viscosity of the component polysaccharide solutions, showing a synergistic viscosity property. The quantitative determination of the hysteresis loop area, developed during viscometer tests on shear rate-shear stress reverse paths, was used to describe the thixotropic behavior. When compared with aqueous solutions of the component polysaccharides, these polysaccharide blends could afford enhanced thixotropic property. Maximum thixotropy synergism was observed for the HPG/CMC blend with the f (HPG) of 0.67.