Rheological and Flocculation Analysis of Microfibrillated Cellulose Suspension Using Optical Coherence Tomography

Abstract

A sub-micron resolution optical coherence tomography device was used together with a pipe rheometer to analyze the rheology and flocculation dynamics of a 0.5% microfibrillated cellulose (MFC) suspension. The bulk behavior of the MFC suspension showed typical shear thinning (power-law) behavior. This was reflected in a monotonously decreasing floc size when the shear stress exceeded the yield stress of the suspension. The quantitative viscous behavior of the MFC suspension changed abruptly at the wall shear stress of 10 Pa, which was reflected in a simultaneous abrupt drop of the floc size. The flocs were strongly elongated with low shear stresses. With the highest shear stresses, the flocs were almost spherical, indicating a good level of fluidization of the suspension.

Tailoring of rheological properties and structural polydispersity effects in microfibrillated cellulose suspensions

“…6a). This phenomenon can be indepth investigated using imaging techniques such as optical coherence tomography (Lauri et al 2017;Koponen et al 2018) to visualize and quantify apparent fluctuations in rheological properties of the MFC fractions under flow.…”

Analysis of Industry-Related Flows by Optical Coherence Tomography—A Review

“…DOCT obviously offers great potential for rheological analysis. Moreover, combining DOCT data with structural information, also given by DOCT, opens truly unprecedented research prospects for the study of the rheology of opaque fluids (Koponen et al, 2018). The extension to polarization sensitivity makes it possible for OCT to also study birefringent materials (Park et al, 2003;Ju et al, 2013).…”

Yield and Electrical Functionality of the Glass-Laminated Conductive Wires and Connectors

“…Non-destructive structural characterization method, so called optical coherence tomography (OCT) was used in this study to evaluate structural changes caused by lamination and find reasons for the observed features of laminated electronics. OCT is widely used in (bio)medical measurements [18][19] but the same technology has been utilized also in industrial applications [17,[20][21][22][23][24][25][26][27] including the electronics quality inspection and reliability analysis [17,22]. Briefly described, OCT is a light-based imaging method in which backscattered intensity profiles are recorded and typically, by lateral scanning of a probing beam cross-sectional images are composed.…”