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
Pore and Matrix Distribution in the Fiber Wall Revealed by Atomic Force Microscopy and Image Analysis
STFI-Packforsk AB.
STFI-Packforsk AB.
2005 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 6, no 1, 433-438 p.Article in journal (Refereed) Published
Abstract [en]

A method for the ultrastructural investigation of fiber cross-sections based on atomic force microscopy in combination with image analysis is presented. A uniform distribution of pores across the matrix material within the fiber wall was revealed by impregnation of pulp fibers with poly(ethylene glycol). The effects of chemical and mechanical processing on the pore and matrix structure and on the arrangement of the cellulose fibril aggregates were investigated. During chemical processing, changes in the fiber ultrastructure occur: a broadening of the pore and matrix lamella widths in combination with a reduction in their number and an enlargement of the cellulose fibril aggregates. It was found that pores formed during pulping are evenly distributed across the fiber wall in the transverse direction. In contrast, refining increases the pore and matrix lamella width in the fiber wall closest to the middle lamella an effect which gradually decrease in size toward the lumen side.

Place, publisher, year, edition, pages
2005. Vol. 6, no 1, 433-438 p.
Keyword [en]
Atomic force microscopy, Cellulose, Image analysis, Impregnation, Polyethylene glycols, Pore size, Fiber walls, Pore distribution, Pulp fibers
National Category
Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-4935DOI: 10.1021/bm040068xISI: 000226344300055OAI: oai:DiVA.org:kth-4935DiVA: diva2:7107
Note
QC 20101012. Uppdaterad från in press till published (20101012).Available from: 2005-02-14 Created: 2005-02-14 Last updated: 2017-12-05Bibliographically approved
In thesis
1. The cell wall ultrastructure of wood fibres: effects of the chemical pulp fibre line
Open this publication in new window or tab >>The cell wall ultrastructure of wood fibres: effects of the chemical pulp fibre line
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Knowledge of the ultrastructural arrangement within wood fibres is important for understanding the mechanical properties of the fibres themselves, as well as for understanding and controlling the

ultrastructural changes that occur during pulp processing.

The object of this work was to explore the use of atomic force microscopy (AFM) in studies of the cell wall ultrastructure and to see how this structure is affected in the kraft pulp fibre line. This is done in order to eventually improve fibre properties for use in paper and other applications, such as composites. On the ultrastructural level of native spruce fibres (tracheids), it was found that cellulose fibril aggregates exist as agglomerates of individual cellulose microfibrils (with a width

of 4 nm). Using AFM in combination with image processing, the average side length (assuming a square cross-section) for a cellulose fibril aggregate was found to be 15–16 nm although with a broad distribution. A concentric lamella structure (following the fibre curvature) within the

secondary cell wall layer of native spruce fibres was confirmed. These concentric lamellae were formed of aligned cellulose fibril aggregates with a width of about 15 nm, i.e. of the order of a single cellulose fibril aggregate. It was further found that the cellulose fibril aggregates had a

uniform size distribution across the fibre wall in the transverse direction.

During the chemical processing of wood chips into kraft pulp fibres, a 25 % increase in cellulose fibril aggregate dimension was found, but no such cellulose fibril aggregate enlargement occurred during the low temperature delignification of wood into holocellulose fibres. The high temperature in the pulping process, over 100 ºC, was the most important factor for the cellulose fibril aggregate enlargement. Neither refining nor drying of kraft or holocellulose pulp changed the cellulose fibril aggregate dimensions.

During kraft pulping, when lignin is removed, pores are formed in the fibre cell wall. These pores were uniformly distributed throughout the transverse direction of the wood cell wall. The lamellae consisting of both pores and matrix material (“pore and matrix lamella”) became wider and their numeral decreased after chemical pulping. In holocellulose pulp, no such changes were seen.

Refining of kraft pulp increased the width of the pore and matrix lamellae in the outer parts of the fibre wall, but this was not seen in holocellulose.

Upon drying of holocellulose, a small decrease in the width of the pore and matrix lamellae was seen, reflecting a probable hornification of the pulp. Refining of holocellulose pulp led to pore closure probably due to the enhanced mobility within the fibre wall. Enzymatic treatment using

hemicellulases on xylan and glucomannan revealed that, during the hydrolysis of one type of hemicellulose, some of the other type was also dissolved, indicating that the two hemicelluloses were to some extent linked to each other in the structure. The enzymatic treatment also decreased the pore volume throughout the fibre wall in the transverse direction, indicating enzymatic accessibility to the entire fibre wall.

The results presented in this thesis show that several changes in the fibre cell wall ultrastructure occur in the kraft pulp fibre line, although the effects of these ultrastructural changes on the fibre properties are not completely understood.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. 70 p.
Series
Trita-FPT-Report, ISSN 1652-2443 ; 2005:2
Keyword
Chemical engineering, atomic force microscopy, cellulose, cell wall, drying, fiber, Kemiteknik
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-129 (URN)
Public defence
2005-02-18, STFI-salen, Drottning Kristinas väg 61, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20101012Available from: 2005-02-14 Created: 2005-02-14 Last updated: 2010-10-12Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Fahlén, Jesper
In the same journal
Biomacromolecules
Chemical Engineering

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 72 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