University of Oulu

Lauri, J., Haavisto, S., Salmela, J. et al. Online measurement of floc size, viscosity, and consistency of cellulose microfibril suspensions with optical coherence tomography. Cellulose 28, 3373–3387 (2021).

Online measurement of floc size, viscosity, and consistency of cellulose microfibril suspensions with optical coherence tomography

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Author: Lauri, Janne1; Haavisto, Sanna2; Salmela, Juha2;
Organizations: 1Faculty of Information Technology and Electrical Engineering, Optoelectronics and Measurement Techniques Research Unit, University of Oulu, P.O. Box 4500, 90014 Oulu, Finland
2Spinnova Ltd, Paloka¨rjentie 2-4, 40320 Jyväskylä, Finland
3Department of Physics, University of Jyväskylä, P.O. Box 35, 40014, Jyväskylä, Finland
4VTT Technical Research Centre of Finland Ltd, P.O. Box 1603, 40101, Jyväskylä, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.7 MB)
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Language: English
Published: Springer Nature, 2021
Publish Date: 2021-06-04


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. 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. The structural OCT images were used to calculate the radial and the axial floc sizes of the suspension. 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 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. The results also showed that an apparent attenuation coefficient of the OCT signal can be used to determine the consistency of CMF suspensions.

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Series: Cellulose
ISSN: 0969-0239
ISSN-E: 1572-882X
ISSN-L: 0969-0239
Volume: 28
Issue: 6
Pages: 3373 - 3387
DOI: 10.1007/s10570-021-03745-6
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
114 Physical sciences
Funding: The work is part of the Academy of Finland’s Flagship Programme under Project No. 318891 (Competence Center for Materials Bioeconomy, FinnCERES). Open access funding provided by VTT Technical Research Centre of Finland Ltd.
Copyright information: © The Author(s) 2021. Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit