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
Ultrastructural changes in a holocellulose pulp revealed by enzymes, thermoporosimetry and atomic force microscopy
STFI-Packforsk AB.
STFI-Packforsk AB.
2005 (English)In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 59, no 6, 589-597 p.Article in journal (Refereed) Published
Abstract [en]

To increase our knowledge of the ultrastructure within softwood fibres, enzymatic treatment, thermoporosimetry, light microscopy, and atomic force microscopy with image analysis were used to investigate the structure of holocellulose softwood pulp fibres. The size of the average cellulose fibril aggregates and the width of pore and matrix lamellae were found to be uniform across the secondary cell-wall layer in the transverse direction of the wood fibre wall. In holocellulose, these dimensions were very similar to those in the native wood, whereas in kraft pulp the cellulose fibril aggregates were larger and the pore and matrix lamellae broader. These differences between holocellulose and kraft pulp fibres suggest that a high temperature is needed for cellulose fibril aggregation to occur. Neither refining nor drying of the holocellulose pulp changed the cellulose fibril aggregate size. Upon drying and enzymatic treatment, a small decrease in the pore and matrix lamella width was evident throughout the fibre wall. This indicated not only uniform distribution of pores throughout the fibre wall, but also enzymatic accessibility to the entire fibre wall. The holocellulose pulp had a somewhat larger pore volume than the kraft pulp. Refining of the holocellulose pulp led to pore closure, probably due to increased mobility of the fibre wall. The enzymatic treatment revealed that during hydrolysis of one hemicellulose, part of the other was also dissolved, indicating that the two hemicelluloses are to some extent linked to each other in the structure.

Place, publisher, year, edition, pages
2005. Vol. 59, no 6, 589-597 p.
Keyword [en]
atomic force microscopy, cell wall, cellulose, drying, enzyme, fibril, hemicellulases, hemicellulose, holocellulose, Norwegian spruce, Picea abies, pores, pore size, pore volume, refining, ultrastructure
National Category
Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-4936DOI: 10.1515/HF.2005.096ISI: 000233697900001OAI: oai:DiVA.org:kth-4936DiVA: diva2:7108
Note
QC 20101012. Uppdaterad från submitted till published (20101012). Tidigare titel: Ultrastructural changes in a holocellulose pulp revealed by enzymes, thermoporosimetry and atomic force microscopyAvailable 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
Holzforschung
Chemical Engineering

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 111 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