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Pipe rheology of microfibrillated cellulose suspensions
2019
Zenodo
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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
doi:10.5281/zenodo.3413909
fatcat:ffgye4oqc5amxpz6uvft2c5kum
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... 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.
Pipe rheology of microfibrillated cellulose suspensions
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
doi:10.1007/s10570-019-02784-4
fatcat:xowibo56wvavlbvmk2yrj4creq
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... onsistency 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.
Improving Compression Recovery of Foam-formed Fiber Materials
2018
BioResources
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Foam technology enables the preparation of new fiber-based materials with reduced density and improved mechanical performances. By utilizing multi-scale structural features of the formed fiber network, it is possible to enhance the elasticity of lightweight cellulose materials under compressive loads. Sufficient strength is achieved by optimally combining fibers and fines of different length-scales. Elasticity is improved by adding polymers that accumulate at fiber joints, which help the
doi:10.15376/biores.13.2.4058-4074
fatcat:3wumhwyuhnfq5kpcfwsscestyy
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... structure to recover after compression. This concept was demonstrated using natural rubber as the polymer additive. For a model network of viscose fibers and wood fines, the immediate elastic recovery after 70% compression varied from 60% to 80% from the initial thickness. This was followed by creep recovery, which reached 86% to 88% recovery within a few seconds in cross-linked samples. After 18 h, the creep recovery in those samples was almost complete at up to 97%. A similar improvement was seen for low-density materials formed with chemi-thermomechanical fibers. The formed structure and elastic properties were sensitive not only to the raw materials, but also to the elastomer stiffness and foam properties. The improved strain recovery makes the developed cellulose materials suitable for various applications, such as padding for furniture, panels, mattresses, and insulation materials.
Recycling of 3D Printable Thermoplastic Cellulose-Composite
2022
Sustainability
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3D printing enables sustainable product innovations through novel design, reduced use of materials, and local manufacturing. Sustainable 3D printing can further be realized using recyclable materials. Cellulose is an abundantly available renewable material. Modified celluloses, such as thermoplastic cellulose esters, are widely used in injection molding applications. The aim of this research was to study the properties of a cellulose-based composite (cellulose acetate propionate (CAP) polymer
doi:10.3390/su14052734
fatcat:3zogbzffxvcizamk3ryfdo422e
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... trix with 20 wt. % microcellulose) in injection molding and granular extrusion-based 3D printing processes over multiple recycles. The impact of the processing methods on the composite's properties were investigated. Both injection molded and 3D printed samples were ground with plastic grinding mill to particle sizes below 3 mm after each preparation stage and reused as such in the next process cycle. Morphology, mechanical and thermal properties, and material degradation were analyzed. The thermoplastic cellulose-based compound was found to be directly recyclable for both processes without the need for any additional compounding steps. The polymer matrix was able to withstand at least seven processing cycles without degradation. However, microcellulose was found to be more sensitive to thermal stress. The mechanical and thermal properties of the cellulose-based composites remained close to initial levels throughout.
Shape fidelity and structure of 3D printed high consistency nanocellulose
2019
Scientific Reports
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The aim of the present study was to investigate the additive manufacturing process for high consistency nanocellulose. Unlike thermoformable plastics, wood derived nanocelluloses are typically processed as aqueous dispersions because they are not melt-processable on their own. The ability to use nanocellulose directly in additive manufacturing broadens the possibilities regarding usable raw materials and achievable properties thereof. Modern additive manufacturing systems are capable of
doi:10.1038/s41598-019-40469-x
pmid:30846757
pmcid:PMC6405753
fatcat:ijsm7rlygvgave2nwzchyu2r6i
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... ng nanocellulose with micrometer precision, which enables the printing of accurate three-dimensional wet structures. Typically, these wet structures are produced from dilute aqueous fibrillar dispersions. As a consequence of the high water content, the structures deform and shrink during drying unless the constructs are freeze-dried. While freeze-drying preserves the geometry, it results in high porosity which manifests as poor mechanical and barrier properties. Herein, we study an additive manufacturing process for high consistency enzymatically fibrillated cellulose nanofibers in terms of printability, shape retention, structure, and mechanical properties. Particular emphasis is placed on quantitative shape analysis based on 3D scanning, point cloud analysis, and x-ray microtomography. Despite substantial volumetric as well as anisotropic deformation, we demonstrate repeatability of the printed construct and its properties.
Microstructure, porosity and mineralogy around fractures in Olkiluoto bedrock
2012
Engineering Geology
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Analysis and visualisation The 3D tomographic data were first filtered for noise with an in-house algorithm (Turpeinen et al. 2012a) . ...
To achieve this, the surface of the sample was first determined with an algorithm (Turpeinen et al. 2012b ) that forced a dynamic 3D interface to approach the surface until it reached force equilibrium ...
doi:10.1016/j.enggeo.2012.04.008
fatcat:ppw57362xnff5cmv47hbult2wm
A STOCHASTIC SHAPE AND ORIENTATION MODEL FOR FIBRES WITH AN APPLICATION TO CARBON NANOTUBES
2012
Image Analysis and Stereology
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Methods are introduced for analysing the shape and orientation of planar fibres from greyscale images of fibrous systems. The sequence of image processing techniques needed for segmentation of fibres is described. The identified fibres were interpreted as deformed line segments for which two shape and two orientation parameters are estimated by the maximum likelihood method. The methods introduced are shown to perform quite well for simulated systems of deformed line segments with known
doi:10.5566/ias.v31.p17-26
fatcat:vh5zmqdka5euvkjwqhdxq75p3y
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... es. They were applied to TEM images of carbon nanotubes embedded in polycarbonate.
On-chip purification via liquid immersion of arc-discharge synthesized multiwalled carbon nanotubes
2016
Applied Physics A: Materials Science & Processing
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Cellulose nanofibrils prepared by gentle drying methods reveal the limits of helium ion microscopy imaging
2019
RSC Advances
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TEMPO-oxidized cellulose nanofibrils (TCNFs) have unique properties, which can be utilised in many application fields from printed electronics to packaging.
doi:10.1039/c9ra01447k
pmid:35514833
pmcid:PMC9064282
fatcat:hckla5gmazepbgunjrc3mzbrxy
Effects of diet-induced obesity and voluntary wheel running on the microstructure of the murine distal femur
2011
Nutrition & Metabolism
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Obesity and osteoporosis, two possibly related conditions, are rapidly expanding health concerns in modern society. Both of them are associated with sedentary life style and nutrition. To investigate the effects of diet-induced obesity and voluntary physical activity we used high resolution micro-computed tomography (μCT) together with peripheral quantitative computed tomography (pQCT) to examine the microstructure of the distal femoral metaphysis in mice. Methods: Forty 7-week-old male
doi:10.1186/1743-7075-8-1
pmid:21241467
pmcid:PMC3034661
fatcat:gionac4zsva2jaqvkz47z7maji
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... mice were assigned to 4 groups: control (C), control + running (CR), high-fat diet (HF), and high-fat diet + running (HFR). After a 21-week intervention, all the mice were sacrificed and the left femur dissected for pQCT and μCT measurements. Results: The mice fed the high-fat diet showed a significant weight gain (over 70% for HF and 60% for HFR), with increased epididymal fat pad mass and impaired insulin sensitivity. These obese mice had significantly higher trabecular connectivity density, volume, number, thickness, area and mass, and smaller trabecular separation. At the whole bone level, they had larger bone circumference and cross-sectional area and higher density-weighted maximal, minimal, and polar moments of inertia. Voluntary wheel running decreased all the cortical bone parameters, but increased the trabecular mineral density, and decreased the pattern factor and structure model index towards a more plate-like structure. Conclusions: The results suggest that in mice the femur adapts to obesity by improving bone strength both at the whole bone and micro-structural level. Adaptation to running exercise manifests itself in increased trabecular density and improved 3D structure, but in a limited overall bone growth.
How many lived to maturity?
1993
Finnish Yearbook of Population Research
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Turpeinen 1984) . ...
Juha Tuomas' son and Anna Jouppila (married in 1708) had 14 children, o f whom 12 died before reaching maturity.
n t o f c h i l d w e l f a r e in F i n l a n d ) . ...
doi:10.23979/fypr.44867
fatcat:xiabftzmmfdfrawrqesxmb6dce
Työkyvyn talo -mallin soveltuvuus yhteisölliseen terveyden ja työkyvyn edistämiseen
2019
Arbetslivsforskning
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(Turpeinen ym. 2016) . ...
Ko ke muk sellista osaamista muodostuu yksilön työko kemuksen ja ammattitaidon kautta opittujen käytännön taitojen ja tietojen, "ammattitaito, osaaminen ja niiden tuoma työkokemus", kaut ta. ...
doaj:f2bb4538c69b451d9dfc60914f110db2
fatcat:iql4yjtpurhwdexhvih4qvjixy
Aikamatriiseja asiantuntijatyössä
2019
Arbetslivsforskning
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(nainen, muu sektori)
Myös sähköinen matriisi ja sen tuoma uusi ryt-
mi voivat osaltaan heijastua asiantuntijoiden
autonomiaan. ...
Abstrakti
Minna Toivanen, Olli Viljanen & Merja Turpeinen Aikamatriiseja asiantuntijatyössä
Johdanto
Aika ja asiantuntijatyö Työllä on vahva ajallinen ulottuvuus. ...
doaj:d71b4c2af6224438a51db3f6cdfb80ed
fatcat:5hutbvr4w5acfefi2deuw3xbve
Dielectric breakdown strength of epoxy bimodal-polymer-brush-grafted core functionalized silica nanocomposites
2014
IEEE transactions on dielectrics and electrical insulation
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ACKNOWLEDGMENT S.V. thanks Tuomas Turpeinen for his indispensable contribution concerning quantifying the particle dispersion. One of us (H. ...
doi:10.1109/tdei.2014.004415
fatcat:2glinzjyw5a5zazwpejca6t5ru
On the strength improvement of lightweight fibre networks by polymers, fibrils and fines
2020
Cellulose
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Tuomas Turpeinen, Annika Ketola, Päivi Sarja, Meiju Sinkkonen, and Timo Rantanen are appreciated for their laboratory and analysis work. Funding Funding was provided by Tekes and VTT. ...
However, based on the work of Turpeinen et al. (2018) and the realized grammages, we assume high, over 90% retention. ...
doi:10.1007/s10570-020-03263-x
fatcat:eew5m3uptbec5j7rizmtjcorva
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