For these reasons, CMFs easily form networks that are often encountered as flocs, gels, and films, and therefore, the gross structure of the CMF suspensions is much larger than the size of individual fibrils (Hubbe et al. The specific surface area (and, thus, hydroxyl group surface density) is much higher for CMF fibrils than for regular cellulose fibers. Typically, the fibrils exhibit diameters at a scale of tens of nanometers and length to diameter ratios (aspect ratios) in the hundreds. The size distribution of the fibrils obtained is broad and varies a great deal depending on the disintegration process. The cellulose fibers are at that point broken down into bundles of individual CMF fibrils. CMFs are obtained from wood or plant cells through a chemical, enzymatic, or mechanical homogenization process (Desmaisons et al. 2015), and in energy-storage devices (Kim et al. 2020), as a rheology modifier (Dimic-Misic et al. 2008), in various membranes and barrier films (Lavoine et al. CMFs are already being utilized in many applications, such as to reinforce paper and composite materials (Cheng et al. The results also showed that an apparent attenuation coefficient of the OCT signal can be used to determine the consistency of CMF suspensions.Ĭellulose microfibrils (CMFs) are a sustainable and a biodegradable material that make it possible to develop novel, all-cellulose products due to, for instance, its lightness, mechanical robustness, and barrier properties (Klemm et al. The dependence of viscosity and floc size on shear stress was similar, indicating that the shear thinning behavior of CMF suspensions is closely related to the rupture dynamics of flocs. A fit of power law to the geometrical floc size–shear stress data gave the same power law index for all consistencies, suggesting that floc rupture dynamics is independent of consistency. The structural OCT images were used to calculate the radial and the axial floc sizes of the suspension.

The viscosities obtained by combining pressure loss measurement with the OCT velocity data showed typical shear thinning behavior and were in excellent agreement with viscosities obtained with ultrasound velocity profiling. In this study, cellulose microfibril (CMF) suspensions were imaged during pipe flow at consistencies of 0.4%, 1.0%, and 1.6% with optical coherence tomography (OCT) to obtain images of the structure and the local velocity of the suspension.

Kinematic viscosity testing size 650