セルロースナノクリスタル水性懸濁液の流動誘起相変化現象

抄録

Cellulose nanocrystals (CNC) are rod-like nanomaterials extracted by acid hydrolysis from cellulose, with lengths in the range of hundreds of nanometers. CNC exhibits unique properties such as high specific stiffness, light weight, and birefringence, making it a promising material for multifunctional applications, especially when dispersed in fluids. CNC aqueous suspensions show shear thinning behavior, and depending on concentration, they can form cholesteric liquid crystalline phases. The internal structure of the CNC suspensions was investigated using polarized light microscopy, and rheo-optical measurements were performed to study the structural changes under different conditions. Rheological measurements were conducted with a stress-controlled rheometer, and the flow history was carefully controlled to avoid measurement discrepancies. The suspension was exposed to a controlled shearing process and temperature variations during the experiments. Creep tests and hysteresis loop experiments were carried out at different temperatures to study the viscosity response under applied shear stress. Small angle light scattering (SALS) was also used to capture the scattering patterns during the rheological measurements, providing insights into the internal structural changes. The results indicated that at lower temperatures, the cholesteric domains were more prominent and influenced the flow behavior, whereas at higher temperatures, the viscosity decreased due to structural rearrangements. These findings highlight the importance of understanding both the transient rheological behavior and the internal structure for industrial applications of CNC suspensions.