Abstract:

The rheological properties of sodium carboxymethyl cellulose （CMC） in glycerol-water mixed solvents with different mass fractions of glycerol were studied on an Anton Paar MCR 302 Rheometer. The mass fractions of glycerol were 0%, 20%, 40%, 60% and 80%, respectively. The results showed that the CMC in different mixed solvents showed no yield stress and they were pseudoplastic fluids with shear-thinning behavior. With the increase of glycerol content, the viscosity of the CMC solution gradually increased; the shear-thinning properties became more obvious; the recovery of solution structure became slow; and the CMC solution gradually changed from a viscoelastic fluid to a viscoelastic solid, in which the internal structure was strengthened and the rigidity was increased. After high-temperature treatment, the viscosities of CMC solutions in the mixed solvents were significantly increased, and the increment was increased with the increase of glycerol content. The molecular backbones of hydrophilic polysaccharide polymers such as CMC have hydroxyl groups and can form hydrogen bonds. The glycerol molecule contains three hydroxyl groups, and its ability of formation of hydrogen bonds with water is strong. Therefore, glycerol can promote the hydrogen bonding between hydroxyl groups in the system, i.e., increase the number of hydrogen bonds and the strength of hydrogen bonding, and thus increase the entanglement of molecular chains and molecular segments.

Key words: rheological property, sodium carboxymethyl cellulose, glycerin