Rheological properties of cellulose nanocrystal-polymeric systems

Rod-like cellulose nanocrystals (CNC) were incorporated into different systems containing polymers (most of them are soluble polysaccharides, such as chitosan, gum arabic, sodium alginate, hydroxypropyl methylcellulose and sodium carboxylmethyl cellulose) of varying charge properties and molecular structures. The dependence of the thickening and rheological behavior of CNC dispersion with concentration were compared with classic models for spheres. It is evident that rod-like particles are more effective in achieving viscosity enhancement at lower particle loading. By varying the concentrations of each polymeric system, the phase diagrams of non-absorbing and absorbing polymers were determined. The gelation behavior of anisotropic CNC dispersion in the presence of various kinds of polymers was investigated, and the thickening effect has the following trends: cationic > anionic > nonionic. In addition, the molecular weight and conformation of the polymer chains had an impact on the viscosity. Hydroxypropyl methylcellulose is the most effective in promoting gelation of 3 wt% CNC dispersion. Understanding the rheological properties of various CNC-polymer complexes will be critical for their application in oil and gas, food and consumer goods.