Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Microfibrillated cellulose: Energy-efficient preparation techniques and key properties
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This work describes three alternative processes for producing microfibrillated cellulose (MFC) in which pulp fibres are first pre-treated and then homogenized using a high-pressure homogenizer. In one process, fibre cell wall delamination was facilitated with a combined enzymatic and mechanical pre-treatment. In the two other processes, cell wall delamination was facilitated by pre-treatments that introduced anionically charged groups into the fibre wall, by means of either a carboxymethylation reaction or irreversibly attaching carboxymethyl cellulose (CMC) onto the fibres. All three processes are industrially feasible and enable production with low energy consumption. Using these methods, MFC can be produced with an energy consumption of 500–2300 kWh/tonne, which corresponds to a 91–98% reduction in energy consumption from that presented in earlier studies. These materials have been characterized in various ways and it has been demonstrated that the produced MFCs are approximately 5–30 nm wide and up to several microns long.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , 49 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 38
Keyword [en]
Microfibrillated cellulose, microfibrillar cellulose, nanofibrillated cellulose nanofibrillar cellulose, nanocellulose, MFC, NFC, production techniques, energy efficient, gel properties, films, enzymes, carboxymethylation, carboxymethyl cellulose, CMC, mechanical properties, oxygen barrier, homogenization
National Category
Paper, Pulp and Fiber Technology
Identifiers
URN: urn:nbn:se:kth:diva-102949ISBN: 978-91-7501-464-7 (print)OAI: oai:DiVA.org:kth-102949DiVA: diva2:557668
Presentation
2012-10-17, STFI-salen, Innventia AB, Drottning Kristinas väg 61, KTH, Stockholm, 14:02 (Swedish)
Opponent
Supervisors
Note

QC 20120928

Available from: 2012-09-28 Created: 2012-09-28 Last updated: 2012-10-03Bibliographically approved
List of papers
1. Enzymatic hydrolysis combined with mechanical shearing and high-pressure homogenization for nanoscale cellulose fibrils and strong gels
Open this publication in new window or tab >>Enzymatic hydrolysis combined with mechanical shearing and high-pressure homogenization for nanoscale cellulose fibrils and strong gels
Show others...
2007 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, no 6, 1934-1941 p.Article in journal (Refereed) Published
Abstract [en]

Toward exploiting the attractive mechanical properties of cellulose I nanoelements, a novel route is demonstrated, which combines enzymatic hydrolysis and mechanical shearing. Previously, an aggressive acid hydrolysis and sonication of cellulose I containing fibers was shown to lead to a network of weakly hydrogen-bonded rodlike cellulose elements typically with a low aspect ratio. On the other hand, high mechanical shearing resulted in longer and entangled nanoscale cellulose elements leading to stronger networks and gels. Nevertheless, a widespread use of the latter concept has been hindered because of lack of feasible methods of preparation, suggesting a combination of mild hydrolysis and shearing to disintegrate cellulose I containing fibers into high aspect ratio cellulose I nanoscale elements. In this work, mild enzymatic hydrolysis has been introduced and combined with mechanical shearing and a high-pressure homogenization, leading to a controlled fibrillation down to nanoscale and a network of long and highly entangled cellulose I elements. The resulting strong aqueous gels exhibit more than 5 orders of magnitude tunable storage modulus G' upon changing the concentration. Cryotransmission electron microscopy, atomic force microscopy, and cross-polarization/magic-angle spinning (CP/MAS) C-13 NMR suggest that the cellulose I structural elements obtained are dominated by two fractions, one with lateral dimension of 5-6 nm and one with lateral dimensions of about 10-20 nm. The thicker diameter regions may act as the junction zones for the networks. The resulting material will herein be referred to as MFC (microfibrillated cellulose). Dynamical rheology showed that the aqueous suspensions behaved as gels in the whole investigated concentration range 0.125-5.9% w/w, G' ranging from 1.5 Pa to 10(5) Pa. The maximum G' was high, about 2 orders of magnitude larger than typically observed for the corresponding nonentangled low aspect ratio cellulose I gels, and G' scales with concentration with the power of approximately three. The described preparation method of MFC allows control over the final properties that opens novel applications in materials science, for example, as reinforcement in composites and as templates for surface modification.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2007
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-37114 (URN)10.1021/bm061215p (DOI)000247107900023 ()17474776 (PubMedID)
Note

QC 20110801

Available from: 2011-08-01 Created: 2011-08-01 Last updated: 2017-12-08Bibliographically approved
2. The build-up of polyelectrolyte multilayers of microfibrillated cellulose and cationic polyelectrolytes
Open this publication in new window or tab >>The build-up of polyelectrolyte multilayers of microfibrillated cellulose and cationic polyelectrolytes
Show others...
2008 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, no 3, 784-795 p.Article in journal (Refereed) Published
Abstract [en]

A new type of nanocellulosic material has been prepared by high-pressure homogenization of carboxymethylated cellulose fibers followed by ultrasonication and centrifugation. This material had a cylindrical cross-section as shown by transmission electron microscopy with a diameter of 5-15 nm and a length of up to 1 mu m. Calculations, using the Poisson-Boltzmann equation, showed that the surface potential was between 200 and 250 mV, depending on the pH, the salt concentration, and the size of the fibrils. They also showed that the carboxyl groups on the surface of the nanofibrils are not fully dissociated until the pH has reached pH = similar to 10 in deionized water. Calculations of the interaction between the fibrils using the Derjaguin-Landau-Verwey-Overbeek theory and assuming a cylindrical geometry indicated that there is a large electrostatic repulsion between these fibrils, provided the carboxyl groups are dissociated. If the pH is too low and/or the salt concentration is too high, there will be a large attraction between the fibrils, leading to a rapid aggregation of the fibrils. It is also possible to form polyelectrolyte multilayers (PEMs) by combining different types of polyelectrolytes and microfibrillated cellulose (MFC). In this study, silicon oxide surfaces were first treated with cationic polyelectrolytes before the surfaces were exposed to MFC. The build-up of the layers was monitored with ellipsometry, and they show that it is possible to form very well-defined layers by combinations of MFC and different types of polyelectrolytes and different ionic strengths of the solutions during the adsorption of the polyelectrolyte. A polyelectrolyte with a three-dimensional structure leads to the build-up of thick layers of MFC, whereas the use of a highly charged linear polyelectrolyte leads to the formation of thinner layers of MFC. An increase in the salt concentration during the adsorption of the polyelectrolyte results in the formation of thicker layers of MFC, indicating that the structure of the adsorbed polyelectrolyte has a large influence on the formation of the MFC layer. The films of polyelectrolytes and MFC were so smooth and well-defined that they showed clearly different interference colors, depending on the film thickness. A comparison between the thickness of the films, as measured with ellipsometry, and the thickness estimated from their colors showed good agreement, assuming that the films consisted mainly of solid cellulose with a refractive index of 1.53. Carboxymethylated MFC is thus a new type of nanomaterial that can be combined with oppositely charged polyelectrolytes to form well-defined layers that may be used to form, for example, new types of sensor materials.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2008
Keyword
molecular-dynamics simulations, aqueous environment, charged surfaces, ionic-strength, layer, films, adsorption, deposition, poly(ethylenimine), nanoscale
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-17283 (URN)10.1021/la702481v (DOI)000252777700033 ()2-s2.0-39449090645 (Scopus ID)
Note

QC 20100525

Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
3. Highly Transparent Films from Carboxymethylated Microfibrillated Cellulose: The Effect of Multiple Homogenization Steps on Key Properties
Open this publication in new window or tab >>Highly Transparent Films from Carboxymethylated Microfibrillated Cellulose: The Effect of Multiple Homogenization Steps on Key Properties
Show others...
2011 (English)In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 119, no 5, 2652-2660 p.Article in journal (Refereed) Published
Abstract [en]

We produced microfibrillated cellulose by passing carboxymethylated sulfite-softwood-dissolving pulp with a relatively low hemicellulose content (4.5%) through a high-shear homogenizer. The resulting gel was subjected to as many as three additional homogenization steps and then used to prepare solvent-cast films. The optical, mechanical, and oxygen-barrier properties of these films were determined. A reduction in the quantity and appearance of large fiber fragments and fiber aggregates in the films as a function of increasing homogenization was illustrated with optical microscopy, atomic force microscopy, and scanning electron microscopy. Film opacity decreased with increasing homogenization, and the use of three additional homogenization steps after initial gel production resulted in highly transparent films. The oxygen permeability of the films was not significantly influenced by the degree of homogenization, whereas the mean tensile strength, modulus of elasticity, and strain at break were increased by two or three extra homogenization steps.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2011
Keyword
barrier, biopolymers, fibers, gas permeation, mechanical properties
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-28589 (URN)10.1002/app.32831 (DOI)000285310400021 ()2-s2.0-78649949931 (Scopus ID)
Note

QC 20110117

Available from: 2011-01-17 Created: 2011-01-17 Last updated: 2017-12-11Bibliographically approved
4. Method for providing a nanocellulose involving modifying cellulose fibers
Open this publication in new window or tab >>Method for providing a nanocellulose involving modifying cellulose fibers
2009 (English)Patent (Other (popular science, discussion, etc.))
Abstract [en]

The present invention provides a method for the manufacturing of nanocellulose. The method includes a first modification of the cellulose material, where the cellulose fibres are treated with an aqueous electrolyte-containing solution of an amphoteric cellulose derivative. The modification is followed by a mechanical treatment. By using this method for manufacturing nanocellulose, clogging of the mechanical apparatus is avoided. Also disclosed is nanocellulose manufactured in accordance with said method and uses of said cellulose.

National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-102939 (URN)
Patent
AU 2009234498B2 (2014-01-09)
Note

RU 2519257 C2 (2014-06-10);  US 8911591 B2 (2014-12-16)

Available from: 2012-09-28 Created: 2012-09-28 Last updated: 2015-01-27Bibliographically approved

Open Access in DiVA

fulltext(6197 kB)6010 downloads
File information
File name FULLTEXT01.pdfFile size 6197 kBChecksum SHA-512
85a001d0c43aa02873637d0b7dd11ca31e796fd8e463dbf6c630e9ebbc07ad5ef9b3d71b3b81e8e38983ae717fdca76ce0925872f0dfc088175c6649a79ab0f8
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Ankerfors, Mikael
By organisation
Fibre Technology
Paper, Pulp and Fiber Technology

Search outside of DiVA

GoogleGoogle Scholar
Total: 6010 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1867 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf