Abstract
| Original language | English |
|---|---|
| Pages (from-to) | 4715-4728 |
| Number of pages | 14 |
| Journal | Cellulose |
| Volume | 24 |
| Issue number | 11 |
| DOIs | |
| Publication status | Published - 2017 |
| MoE publication type | A1 Journal article-refereed |
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Keywords
- shear viscosity
- yield stress
- lubrication layer
- slip velocity
- velocity profile
- optical coherence tomography
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Analysis of rheology and wall depletion of microfibrillated cellulose suspension using optical coherence tomography. / Lauri, Janne; Koponen, Antti (Corresponding Author); Czajkowski, Jakub; Haavisto, Sanna; Fabritius, Tapio.
In: Cellulose, Vol. 24, No. 11, 2017, p. 4715-4728.Research output: Contribution to journal › Article › Scientific › peer-review
TY - JOUR
T1 - Analysis of rheology and wall depletion of microfibrillated cellulose suspension using optical coherence tomography
AU - Lauri, Janne
AU - Koponen, Antti
AU - Czajkowski, Jakub
AU - Haavisto, Sanna
AU - Fabritius, Tapio
PY - 2017
Y1 - 2017
N2 - A rheometric method based on velocity profiling by optical coherence tomography (OCT) was used in the analysis of rheological and boundary layer flow properties of a 0.5% microfibrillated cellulose (MFC) suspension. The suspension showed typical shear thinning behaviour of MFC in the interior part of the tube, but the measured shear viscosities followed interestingly two successive power laws with an identical flow index (exponent) and a different consistency index. This kind of viscous behaviour, which has not been reported earlier for MFC, is likely related to a sudden structural change of the suspension. The near-wall flow showed existence of a slip layer of 2-12 µm thickness depending on the flow rate. Both the velocity profile measurement and the amplitude data obtained with OCT indicated that the slip layer was related to a concentration gradient appearing near the tube wall. Close to the wall the fluid appeared nearly Newtonian with high shear rates, and the viscosity approached almost that of pure water with decreasing distance from the wall. The flow rates given by a simple model that included the measured yield stress, viscous behavior, and slip behavior, was found to give the measured flow rates with a good accuracy.
AB - A rheometric method based on velocity profiling by optical coherence tomography (OCT) was used in the analysis of rheological and boundary layer flow properties of a 0.5% microfibrillated cellulose (MFC) suspension. The suspension showed typical shear thinning behaviour of MFC in the interior part of the tube, but the measured shear viscosities followed interestingly two successive power laws with an identical flow index (exponent) and a different consistency index. This kind of viscous behaviour, which has not been reported earlier for MFC, is likely related to a sudden structural change of the suspension. The near-wall flow showed existence of a slip layer of 2-12 µm thickness depending on the flow rate. Both the velocity profile measurement and the amplitude data obtained with OCT indicated that the slip layer was related to a concentration gradient appearing near the tube wall. Close to the wall the fluid appeared nearly Newtonian with high shear rates, and the viscosity approached almost that of pure water with decreasing distance from the wall. The flow rates given by a simple model that included the measured yield stress, viscous behavior, and slip behavior, was found to give the measured flow rates with a good accuracy.
KW - shear viscosity
KW - yield stress
KW - lubrication layer
KW - slip velocity
KW - velocity profile
KW - optical coherence tomography
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85029413092&partnerID=MN8TOARS
U2 - 10.1007/s10570-017-1493-5
DO - 10.1007/s10570-017-1493-5
M3 - Article
VL - 24
SP - 4715
EP - 4728
JO - Cellulose
JF - Cellulose
SN - 0969-0239
IS - 11
ER -