Flocculated flow of microfibrillated cellulose water suspensions

An imaging approach for characterisation of rheological behaviour

E. Saarikoski, T. Saarinen, Juha Salmela, J. Seppälä (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

69 Citations (Scopus)

Abstract

Our aim was to characterise the suspension rheology of microfibrillated cellulose (MFC) in relation to flocculation of the cellulose fibrils. Measurements were carried out using a rotational rheometer and a transparent cylindrical measuring system that allows combining visual information to rheological parameters. The photographs were analyzed for their floc size distribution. Conclusions were drawn by comparing the photographs and data obtained from measurements. Variables selected for examination of MFC suspensions were degree of disintegration of fibres into microfibrils, the gap between the cylinders, sodium chloride concentration, and the effects of changing shear rate during the measurement. We studied changes in floc size under different conditions and during network structure decomposition. At rest, the suspension consisted of flocs sintered together into a network. With shearing, the network separated first into chain-like floc formations and, upon further shear rate increase, into individual spherical flocs. The size of these spherical flocs was inversely proportional to the shear rate. Investigations also confirmed that floc size depends on the geometry gap, and it affects the measured shear stress. Furthermore, suspension photographs revealed an increasing tendency to aggregation and wall depletion with sodium chloride concentration of 10−3 M and higher.
Original languageEnglish
Pages (from-to)647-659
Number of pages12
JournalCellulose
Volume19
Issue number3
DOIs
Publication statusPublished - 2012
MoE publication typeA1 Journal article-refereed

Fingerprint

Cellulose
Shear deformation
Suspensions
Sodium chloride
Imaging techniques
Water
Sodium Chloride
Disintegration
Rheometers
Flocculation
Rheology
Shearing
Shear stress
Agglomeration
Decomposition
Geometry
Fibers

Keywords

  • Flocculation
  • image analysis
  • microfibrillated cellulose
  • rheology
  • water suspension

Cite this

Saarikoski, E. ; Saarinen, T. ; Salmela, Juha ; Seppälä, J. / Flocculated flow of microfibrillated cellulose water suspensions : An imaging approach for characterisation of rheological behaviour. In: Cellulose. 2012 ; Vol. 19, No. 3. pp. 647-659.
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Flocculated flow of microfibrillated cellulose water suspensions : An imaging approach for characterisation of rheological behaviour. / Saarikoski, E.; Saarinen, T.; Salmela, Juha; Seppälä, J. (Corresponding Author).

In: Cellulose, Vol. 19, No. 3, 2012, p. 647-659.

Research output: Contribution to journalArticleScientificpeer-review

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T1 - Flocculated flow of microfibrillated cellulose water suspensions

T2 - An imaging approach for characterisation of rheological behaviour

AU - Saarikoski, E.

AU - Saarinen, T.

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AU - Seppälä, J.

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