Rheological Behavior of Nanocellulose Aqueous Suspensions

The rheological properties of aqueous suspensions of spherical and needle-shaped nanocellulose particles in the range of 25–70°C are compared. Nanocellulose samples are obtained by the acid hydrolysis of cotton cellulose fibers in H₂SO₄ (61–65%) at 25–45°C. The shape of nanocellulose particles affects the yield strength and non-Newtonian character of the suspension flow. In the shear stress region above 100 Pa, a decrease in effective viscosity occurs, depending on the shape of the particles and the temperature of the suspension. In the region of the shear rate close to the yield strength, the activation energy of the viscous flow of suspensions of spherical particles is 12 kJ/mol; needle-shaped particles, 18 kJ/mol. Features of the rheological behavior are due to the fact that spherical particles are involved mainly in rotational-translational motion, while the needle-like particles are oriented in the direction of flow.