Influence of hydroxyethyl and carboxymethyl celluloses on the rheology, water retention and surface tension of water-suspended microfibrillated cellulose

Abstract Water-soluble polymers have been shown to improve the flow rigidity and water retention ability of highly-branched (flocculated) polydisperse water-suspended MFC, thereby also modifying controlling their rheological behaviour. The addition hydroxyethyl (HEC) carboxymethyl (CMC) celluloses different content (5–10–20 w/w%), molecular weights (M W , 90.000–1.300.000 g/mol) degrees substitutions (DS, 0.7–1.2) 1.5 wt% MFC suspension, thus studied by evaluating microstructure (SEM imaging), strength properties, i.e. yield stress under rotational (viscosity vs. shear rate) oscillatory (viscoelastic) regime, using cone-plate measuring geometry at a rather low truncation gap. pure suspension showed high-viscosity lower shear-thinning behaviour higher rates, with two yielding zones, indicating secondary deflocculation smaller more stiffly packed fibril structures orientation/aligning in direction flow. This was reduced substantially high-M HEC, or almost eliminated completely medium-M CMCs DS, suspensions stability-prolonged zero-shear viscosity, as well linearly decreased irreversible viscosity profile after load removal stresses. carboxylic groups CMC additionally interactions between fibrils, subsequently fibrils’ flocks, formed larger aggregates integrations, while increasing gel-strength, improving its viscoelastic through surface tension recovery deformation.