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Ultrastructure of the Primary Cell Wall of Softwood Fibres Studied using Dynamic FT-IR Spectroscopy
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
2008 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

The primary cell wall is a complex multipolymer system whose composite structure has been mostly determined from chemical and biochemical studies. Although the primary cell wall serves a central role, with regard to the connective properties of fibres, knowledge about the interactions among the polymers, when it comes to the mechanical properties, is very limited. The physical properties of the polymers, i.e. their elastic and viscous deformations, as well as the ultrastructure of the polymers, i.e. the interactions among the polymers in the outer fibre wall layers that lead to this behaviour, are still not fully understood.

The aim of this study was to examine how the different wood polymers, viz. lignin, protein, pectin, xyloglucan and cellulose, interact in the outer fibre wall layers of the spruce wood tracheid. The initial objective was to separate an enriched primary cell wall material from a first stage TMP, by means of screening and centri-cleaning. From this material, consisting of the primary cell wall (P) and outer secondary cell wall (S1) materials, thin sheets were prepared and analysed using a number of different analytical methods. The major measuring technique used was dynamic Fourier transform infra-red (FT-IR) spectroscopy in combination with dynamic 2D FT-IR spectroscopy. This technique is based on the detection of small changes in molecular absorption that occur when a sinusoidally stretched sample undergoes low strain. The molecular groups affected by the stretching respond in a specific way, depending on their environment, while the unaffected molecular groups provide no response to the dynamic spectra, by producing no elastic or viscous signals. Moreover, the dynamic 2D FT-IR spectroscopy provides useful information about various intermolecular and intramolecular interactions, which influence the reorientability of functional groups in a polymer material.

Measurements of the primary cell wall material, using dynamic FT-IR spectroscopy, indicated that strong interactions exist among lignin, protein and pectin, as well as among cellulose, xyloglucan and pectin in this particular layer. This was in contrast to the secondary cell wall, where interactions of cellulose with glucomannan and of xylan with lignin were dominant. It was also indicated that the most abundant crystalline cellulose in the primary cell wall of spruce wood fibres is the cellulose Iβ allomorph, which was also in contrast to the secondary cell wall, where the cellulose Iα allomorph is more dominant. The presence of strong interactions among the polymers in the primary cell wall and, especially, the relatively high content of pectin and protein, showed that there is a very good possibility of selectively attacking these polymers in the primary cell wall. The first selective reaction chosen was a low degree of sulphonation, applied by an impregnation pretreatment of chips with a very low charge of sodium sulfite (Na2SO3). This selective reaction caused some structural modification of the lignin, a weakening of the interactions between lignin;pectin, lignin;protein and pectin;protein, as well as an increased softening of the sulphonated primary cell wall material, when compared to the unsulphonated primary cell wall material. All this resulted in an increased swelling ability of the material.

Place, publisher, year, edition, pages
Stockholm: KTH , 2008. , 32 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2008:1
Keyword [en]
primary cell wall, polymer interactions, viscoelasticity, dynamic FT-IR spectroscopy, dynamic 2D FT-IR spectroscopy, cellulose, xyloglucan, pectin, protein, lignin, low degree sulphonation, cellulose allomorphs
National Category
Wood Science
Identifiers
URN: urn:nbn:se:kth:diva-4614OAI: oai:DiVA.org:kth-4614DiVA: diva2:13093
Presentation
2008-02-05, Sundbladsalen, STFI-Packforsk AB, Drottning Kristinas väg 61, 114 86 Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101123Available from: 2008-01-25 Created: 2008-01-25 Last updated: 2010-11-23Bibliographically approved
List of papers
1. Characterizing wood polymers in the primary cell wall of Norway spruce (Picea abies (L.) Karst.) using dynamic FT-IR spectroscopy
Open this publication in new window or tab >>Characterizing wood polymers in the primary cell wall of Norway spruce (Picea abies (L.) Karst.) using dynamic FT-IR spectroscopy
2008 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 15, no 2, 285-295 p.Article in journal (Refereed) Published
Abstract [en]

Dynamic Fourier Transform Infra-Red (FT-IR) spectroscopy was used to examine the interactions among cellulose, xyloglucan, pectin, protein and lignin in the outer fibre wall layers of spruce wood tracheids. Knowledge regarding these interactions is fundamental for understanding the fibre separation in a mechanical pulping process. Sheets made from an enriched primary cell wall material were used for studying the viscoelastic response of the polymers. The results indicated that strong interactions exist among lignin, protein, pectin, xyloglucan and cellulose in the primary cell wall. This signified a closely linked network structure of the components on the fibre surface. This ultrastructural arrangement in the primary cell wall and the relatively high content of lignin, pectin and protein in it, means that the primary cell wall is more submissive to selective chemical attacks, when compared to the secondary cell wall. A low ratio of cellulose I alpha to cellulose I beta in the primary cell wall was also found.

Keyword
CTMP, dynamic FT-IR spectroscopy, interaction, Norway spruce, Picea abies (L) Karst, polymers, primary cell wall, TMP
National Category
Wood Science
Identifiers
urn:nbn:se:kth:diva-7917 (URN)10.1007/s10570-007-9169-1 (DOI)000253524800011 ()
Note
QC 20101123 Uppdaterad från accepted till published (20101123).Available from: 2008-01-25 Created: 2008-01-25 Last updated: 2017-12-14Bibliographically approved
2. The primary cell wall studied by dynamic 2D FT-IR: Interaction among components in Norway spruce (Picea abies)
Open this publication in new window or tab >>The primary cell wall studied by dynamic 2D FT-IR: Interaction among components in Norway spruce (Picea abies)
2006 (English)In: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 40, no 9-10, 761-767 p.Article in journal (Refereed) Published
Abstract [en]

Knowledge on the interactions among the wood polymers, viz. cellulose, hemicellulose, pectin, lignin and protein, in the outer fibre wall layers is essential for understanding fibre separation in thermomechanical and chemithermomechanical pulping processes. For this reason, dynamic two-dimensional Fourier Transform Infra-Red (2D FT-IR) spectroscopy was applied to examine the interaction of these components in the primary cell wall of spruce fibres. Sheets made of an enriched primary cell wall material were used for studying the viscoelastic response to loading. The dynamic 2D correlation FT-IR spectra indicated the existence of strong interactions between lignin and protein, as well as among pectin, xyloglucan and cellulose, in the primary cell wall. This is in contrast to the picture for the secondary cell wall, in which cellulose-glucomannan and xylan-lignin interactions are prevailing.

Keyword
Norway spruce, 2D FT-IR spectroscopy, primary cell-wall, interaction, polymers
National Category
Wood Science
Identifiers
urn:nbn:se:kth:diva-7918 (URN)000253171500011 ()
Note
QC 20101123Available from: 2008-01-25 Created: 2008-01-25 Last updated: 2017-12-14Bibliographically approved
3. Interactions among Components in the Primary Cell Wall of Norway Spruce (Picea Abies (L.) Karst.): Effect of a Low Sulphonation Pretreatment
Open this publication in new window or tab >>Interactions among Components in the Primary Cell Wall of Norway Spruce (Picea Abies (L.) Karst.): Effect of a Low Sulphonation Pretreatment
2008 (English)In: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 34, no 2, 107-112 p.Article in journal (Refereed) Published
Abstract [en]

Dynamic Fourier Transform Infra-Red (FT-IR) spectroscopy was used to examine the effect of a low sulphonation treatment on the ultrastructure of the primary cell wall of spruce wood. Sheets made from enriched primary cell wall material coming from a low sulphonated thermomechanical pulp were used for studying the viscoelastic response of the polymers using dynamic FT-IR spectroscopy. The overall ultrastructure of the primary cell wall remained largely unaltered, due to the exceptionally low degree of sulphonation used. However, an increased softening of the material as well as a weakening of the lignin,pectin, lignin, protein and pectin, protein interactions were observed. The suggestion is that, together with a structural modification of the lignin, it is the increased viscoelasticity of the material, resulting from the breaking down of the interactions among the polymers, that is the cause for the lower energy demand, when refining correspondingly low sulphonated chips.

Keyword
Norway spruce, Picea Abies (L.) Karst., Dynamic FT-IR spectroscopy, Primary cell wall, Interaction, Polymers, Sulphonation, Sodium sulphite, Pretreatment, Chips, Energy consumption
National Category
Wood Science
Identifiers
urn:nbn:se:kth:diva-7919 (URN)000261815400005 ()
Note
QC 20101123 Uppdaterad från accepted till published (20101123).Available from: 2008-01-25 Created: 2008-01-25 Last updated: 2017-12-14Bibliographically approved

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