Estimation of Aspect Ratio of Cellulose Nanocrystals by Viscosity Measurement: Influence of Aspect Ratio Distribution and Ionic Strength

Abstract

The influence of the cellulose nanocrystal (CNC) aspect ratio (L/d) distribution and ionic strength of different salts on the L/d estimation by viscosity measurement were investigated. The L/d distribution was controlled by mixing two CNC, with different L/d, which were prepared by acid hydrolysis from wood and bacterial cellulose. The results demonstrated that the L/d distribution did not affect the accuracy of the CNC L/d estimated by viscosity measurements using the Batchelor equation, and the calculated L/d was the number-average L/d. Moreover, monovalent (NaCl), divalent (CaCl2), and trivalent (AlCl3) salts were chosen to study the influence of ionic strength on the CNC L/d estimation by viscosity measurement. It was found that NaCl and CaCl2 could be added to the CNC suspension to screen the electro-viscous effect and estimate the actual physical CNC L/d by viscosity measurement, and the content of NaCl and CaCl2 can be predicted by the Debye–Hückel theory. However, a small amount of AlCl3 induced CNC aggregation and increased intrinsic viscosity and predicted L/d.

Agglomeration of cellulose nanocrystals: the effect of secondary sulfates and their use in product separation

“…Thus, a significant effort has been made to understand and to tune their colloidal stability. Several works have addressed the effect of electrolytes and ionic species on the agglomeration and gelation behavior of colloidal CNCs (Dong et al 1996;Dong and Gray 1997;Boluk et al 2011;Shafiei-Sabet et al 2014;Cherhal et al 2015;Peddireddy et al 2016;Phan-Xuan et al 2016;Bertsch et al 2017;Mikhailov et al 2017;Wu et al 2017Wu et al , 2019Liu et al 2018;Moud et al 2018Moud et al , 2019Qi et al 2019). All of the aforementioned studies focused on agglomeration of sulfated CNCs induced by chlorides, with inorganic counterions of varying valence.…”

Experimental and numerical simulation study on the flow characteristics and optimization of structural parameters of displacement agent in partial pressure tools

“…However, with the increase of the flow space, the flow state of the solution is diffusion‐like. Due to the elasticity of the molecular chain, it can generate an elastic restoring force after stretching, causing the molecular chain to shrink and the overall structure to become compact, with a macroscopic increase in viscosity . From the viscosity curve, it can be seen that in the periodic shearing process, the shearing effect is greater than the elastic recovery effect, which leads to a viscosity reduction of the polymer solution.…”

“…Due to the elasticity of the molecular chain, it can generate an elastic restoring force after stretching, causing the molecular chain to shrink and the overall structure to become compact, with a macroscopic increase in viscosity. [61][62][63][64][65][66][67][68] From the viscosity curve, it can be seen that in the periodic shearing process, the shearing effect is greater than the elastic recovery effect, which leads to a viscosity reduction of the polymer solution. After the accumulation of the shearing effect of the throttling unit, the viscosity of the polymer solution decreases by 6.69%.…”

Green nanocomposites from Salvia-based waterborne polyurethane-urea dispersions reinforced with nanocellulose

“…By averaging 100 CNC entities in the height profile and height image, length and diameter values of 167 ± 101 and 5.6 ± 1.5 nm, respectively, were determined, resulting in a L/D aspect ratio of 30. The aspect ratio value is a key parameter determining the performance of the CNC in the nanocomposite [21]. The higher the value, greater reinforcing capacity will provide to the system.…”