Effect of Fiber Concentration and Axial Ratio on the Rheological Properties of Cellulose Fiber Suspensions.

Abstract

The steady flow and the dynamic viscoelastic properties of cellulose fiber suspensions were investigated as functions of the suspension concentration and the fiber shape using a parallel-plate type rheometer. Various concentrations of the suspensions were made from various types of cellulose fibers, i.e., microcrystalline cellulose, bacterial cellulose, and fibrillated cellulose fibers. All the suspensions showed non-Newtonian flow even at very low concentrations. The flow property of each suspension showed a plateau of the shear stress, i.e., the yield stress, over a critical concentration. The critical concentration obtained from the experiment agreed well with the value theoretically calculated from the axial ratio of the fibers. The dynamic moduli of the suspensions were almost independent of the angular frequency, and they increased with the fiber concentration. The dynamic storage moduli increased in proportion to the 9/4th power of the fiber concentration. This power of 9/4 is coincident with that theoretically required for polymer gels. This fact suggests that the rigidity of the suspensions has appeared by the same mechanism from the order of cellulose fibers to microcrystalline cellulose fibers, and even to polymer molecules.

Microrheological measurement of microcrystalline cellulose solution using single particle tracking

“…It shows non-Newtonian behaviour when diluted with water at low concentrations, independent to angular frequency. Furthermore, magnitude of its dynamic storage reaches plateau condition in relative high concentrations with storage moduli bigger than ten times than the loss moduli [8][9]. As reported in other research, the treatment using sonication process can altered the morphology structure and tensile modulus of these cellulose solutions.…”

The rheological behavior and thermal conductivity of melt-compounded polycarbonate/vapor-grown carbon fiber composites

“…[24][25][26][27][28][29][30] According to these reports, a power law correlation was found between the plateau modulus G¢ and the volume concentration c v , namely, G¢¼k c v a where k and a are parameters that are independent of c v . Tatsumi et al 29,30 have also explained that the k is the index of fiber flexibility, which depends on Young's modulus and the aspect ratio of the fiber. The result of the investigation of the plateau modulus and the content of VGCF in Figure 3 was that log G¢ was proportional to log c v of VGCF-s in the PC-L/VGCF-s system.…”

“…The same researchers have also obtained the mathematical relationship between the modulus and concentration in a pulp fiber suspension system. [25][26][27][28][29] Tatsumi 30 has reported that the elastic modulus and the concentration of the pulp fiber are related by a power law. On the basis of the polymer gel solution system, Tatsumi has also reported that a power law could be theoretically expressed in the microfiber suspension system.…”

Viscoelastic Properties of Pulp Suspensions of Bleached Sugarcane Bagasse: Effects of Consistency and Temperature

“…The potential of fiber suspensions to form networks that help transmit stresses, in addition to the flocculation phenomena, among other factors, results in a non-Newtonian behavior (Kerekes 2006;Bousfield 2008;Derakhshandeh et al 2011), exhibiting viscoelastic properties. This has practical implications in many stages of the papermaking and bioconversion processes, e.g., during the transport of fiber suspensions, the forming of paper (Tatsumi et al 2002), and mixing of biomass slurries (Nutsen and Liberatore 2009). Therefore, is then of crucial interest to know the rheology of bagasse suspensions to ensure optimal process implementation and the right selection of equipment.…”