Analysis of rheology and wall depletion of microfibrillated cellulose suspension using optical coherence tomography

Lauri, Janne; Koponen, Antti; Haavisto, Sanna; Czajkowski, Jakub; Fabritius, Tapio

doi:10.1007/s10570-017-1493-5

Cited by 20 publications

(30 citation statements)

References 56 publications

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“…With this setup, it is possible to obtain information on the flow behavior of MNFC suspensions in realistic process-like conditions, as the suspension behaves inside the pipe like a continuum medium and many artefacts seen in traditional rotational rheometers are eliminated. However, the slip flow may also distort the results here, as slip may increase the total pipe flow rate of MNFC suspensions considerably (Haavisto et al 2015a;Nazari et al 2016;Lauri et al 2017).…”

Section: Introductionmentioning

confidence: 79%

“…As a result, the efficiency of momentum transport in the suspension declines and the viscosity decreases (Iotti et al 2011;Petrich et al 2000;Bounoua et al 2016). Note that the structural changes due to increasing shear forces are not always gradual; MNFC suspensions can also encounter abrupt structural changes, which are manifested by a sudden drop in viscosity (Lauri et al 2017). MNFC suspensions have a high flocculation tendency, and they often exhibit strong apparent wall slip due to wall depletion close to solid walls.…”

Section: Introductionmentioning

confidence: 99%

“…MNFC suspensions have a high flocculation tendency, and they often exhibit strong apparent wall slip due to wall depletion close to solid walls. The width of the wall depletion layer can vary between a few micrometers and a few hundred micrometers, depending on the MNFC grade, MNFC consistency, and flow conditions (Haavisto et al 2015a;Lauri et al 2017;Kataja et al 2017). The slip flow makes it challenging to produce reliable information on shear rheology of MNFC using standard rotational rheometer geometries such as plate-plate, cone and plate, and cylinder cup geometries (Saarinen et al 2014;Martoia et al 2015;Vadodaria et al 2018).…”

Section: Introductionmentioning

confidence: 99%

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Pipe rheology of microfibrillated cellulose suspensions

Turpeinen

Jäsberg

Haavisto³

et al. 2019

Cellulose

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The shear rheology of two mechanically manufactured microfibrillated cellulose (MFC) suspensions was studied in a consistency range of 0.2-2.0% with a pipe rheometer combined with ultrasound velocity profiling. The MFC suspensions behaved at all consistencies as shear thinning power law fluids. Despite their significantly different particle size, the viscous behavior of the suspensions was quantitatively similar. For both suspensions, the dependence of yield stress and the consistency index on consistency was a power law with an exponent of 2.4, similar to some pulp suspensions. The dependence of flow index on consistency was also a power law, with an exponent of -0.36. The slip flow was very strong for both MFCs and contributed up to 95% to the flow rate. When wall shear stress exceeded two times the yield stress, slip flow caused drag reduction with consistencies higher than 0.8%. When inspecting the slip velocities of both suspensions as a function of wall shear stress scaled with the yield stress, a good data collapse was obtained. The observed similarities in the shear rheology of both the MFC suspensions and the similar behavior of some pulp fiber suspensions suggests that the shear rheology of MFC suspensions might be more universal than has previously been realized.

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Section: Introductionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pipe rheology of microfibrillated cellulose suspensions

Turpeinen

Jäsberg

Haavisto³

et al. 2019

Cellulose

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“…18 shows, the accuracy of the measurement is very good in the laminar region, and reasonably good in the turbulent region, considering the low viscosity of the water. A corresponding rheological analysis based on velocity profiling and equations (4) and (5) was performed successfully in Lauri et al (2017) for an aqueous suspension of microfibrillated cellulose with a concentration of 0.5 wt%. Fig.…”

Section: Rheologymentioning

confidence: 99%

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

Koponen

Haavisto²

2020

KONA

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Optical Coherence Tomography (OCT) is a light-based imaging method capable of simultaneously capturing the internal structure and motion (1D, 2D or 3D) of various opaque and turbid materials with a micron-level spatial resolution. Depending on the OCT technology, axial scanning rates can vary in a range of tens to hundreds of kHz. The actual imaging depth significantly depends on the optical properties of the material and can vary from micrometers to a few millimeters. From the viewpoint of industrial applications, OCT technology is very appealing. Due to its resolution, speed, and ability to deal with opaque materials, it fills an apparent gap in available measurement methods. Nonetheless, OCT has not to date seen widespread growth in the industrial field. This has been at least partly due to a lack of commercial devices compact and flexible enough to adapt to industrial needs. The recent emergence of more generic commercial OCT devices has considerably lowered the threshold for adapting the technique. The utilization of OCT for structural analysis, also outside the medical field, has been thoroughly discussed in scientific literature. Therefore, in this paper, we will mainly concentrate on applications of OCT that also utilize its capability of performing velocity measurements. The emphasis will be on industrially motivated problems such as rheology, microfluidics, fouling and turbulence.

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“…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.…”

Section: F Optical Coherence Tomography Measurementsmentioning

confidence: 99%

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

Hannila

Augustine

Kurkela

et al. 2019

IEEE Trans. Compon., Packag. Manufact. Technol.

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Large area electronics is becoming an embedded part of structural elements such as automotive and architectural glasses. In this study, the effect of glass lamination based fabrication process on the electrical performance and production throughput yield (TPY) of printed conductive wires and surface mounted (SMD) connectors on polyethylene terephthalate (PET) carrier film were investigated by measuring their electrical conductivity after lamination. Based on the experiments, lamination decreases the production yield of conductive wires and connectors due broken wires or dislocated connectors, especially if they are located close to the corners of laminate. On the other hand, lamination was observed to improve the electrical conductivity of wires. In addition, some potential failure mechanisms are discussed.

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Analysis of rheology and wall depletion of microfibrillated cellulose suspension using optical coherence tomography

Cited by 20 publications

References 56 publications

Pipe rheology of microfibrillated cellulose suspensions

Pipe rheology of microfibrillated cellulose suspensions

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

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

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