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Solubility of Softwood Hemicelluloses
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.ORCID iD: 0000-0003-3572-7798
Abo Akad Univ, Lab Wood & Paper Chem, Johan Gadolin Proc Chem Ctr, FI-20500 Turku, Finland..
Abo Akad Univ, Lab Wood & Paper Chem, Johan Gadolin Proc Chem Ctr, FI-20500 Turku, Finland..
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2018 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 4, p. 1245-1255Article in journal (Refereed) Published
Abstract [en]

It is demonstrated that the molecular solubility of softwood hemicelluloses is significantly influenced by pretreatment of the fibers, extraction, and downstream processing. To quantify these effects, four hemicellulose samples were extracted from different thermomechanical pulps of Norway spruce. The molecular solubility of the samples was characterized by size and molar mass distributions, and the morphology of the molecules was studied using high resolution microscopy techniques. All extracted samples were well dispersed in aqueous media creating transparent dispersions, but dynamic light scattering measurements showed that molecular solubility can only be achieved using specific pretreatments and extractions. The procedure yields acetylated galactoglucomannan (AcGGM)-rich hemicelluloses with an average molar mass of 21-35 kDa and a diameter up to 10 nm but also shows that water is a poor solvent for this sample since an association is detected as soon as the concentration is about 20 g/L. These associated hemicellulose dispersions are still absolutely dear on visual inspection, underlining the need for careful measurement when assessing the solubility of wood hemicelluloses.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018. Vol. 19, no 4, p. 1245-1255
National Category
Biochemistry and Molecular Biology
Identifiers
URN: urn:nbn:se:kth:diva-226772DOI: 10.1021/acs.biomac.8b00088ISI: 000429886500015PubMedID: 29522320Scopus ID: 2-s2.0-85045144605OAI: oai:DiVA.org:kth-226772DiVA, id: diva2:1203267
Note

QC 20180503

Available from: 2018-05-03 Created: 2018-05-03 Last updated: 2019-05-09Bibliographically approved
In thesis
1. On the Solubility of Wood Hemicelluloses in Water and its Influence on the Adsorption at Cellulose/Water Interfaces
Open this publication in new window or tab >>On the Solubility of Wood Hemicelluloses in Water and its Influence on the Adsorption at Cellulose/Water Interfaces
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Hemicelluloses are a group of natural polysaccharides and one of the main components of wood. The availability and biodegradability of these polymers have created a great interest in developing new bio-based materials or composites from these materials for different end-use purposes. To develop new materials from these polysaccharides with better functionalities, it is essential to understand the fundamental properties of these compounds. The solubility of hemicelluloses is one of these crucial characteristics since the material has to be dissolved in an appropriate solvent if these biopolymers are to be used in, for example, dense and strong films once the solvents are removed. The interaction of these polysaccharides with different solid surfaces is also significantly influenced by their solubility at the surface/water interface and an understanding of this interaction is essential for describing composite formation, since the polysaccharides are most frequently used together with reinforcing materials such as anisotropic cellulose fibers and fibrils.

In the work described in this thesis, a novel methodology has been developed for characterizing in detail the solubility of the extracted and model mannans, arabinoxylans and xyloglucan polysaccharides. Different chemical structural analyses, chromatography, light scattering and microscopy techniques have been applied to achieve an accurate understanding of the solubility of the polysaccharides in aqueous media. A careful study has been performed to isolate and purify softwood polysaccharides, followed by the preparation of model samples to investigate the influence of processing, structural substitutions and molar mass on the solubility. Association and the phase separation of hemicelluloses have been identified in aqueous media despite their clear and transparent appearance to the naked eye.

Natural hemicelluloses are used in combination with cellulose as composite materials both to introduce different functionalities and to utilize the great mechanical properties of cellulose fibrils/fibers. Accordingly, there was a great need to study the influence of the solubility on the interaction and adsorption of these polysaccharides at the cellulose/water interface. The adsorption at the cellulose/water interface was indeed affected by the physicochemical structures and solubility of the polysaccharides, and it has been shown that an increasing molar mass and an increasing polymer concentration lead to formation of associated structures and a phase separation at cellulose model surfaces.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019. p. 60
Series
TRITA-CBH-FOU ; 2019:29
Keywords
Wood, Hemicellulose, Solubility, Adsorption, Interaction, Cellulose, Size distribution
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-251110 (URN)978-91-7873-190-9 (ISBN)
Public defence
2019-06-07, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
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Note

QC 2019-05-09

Available from: 2019-05-09 Created: 2019-05-09 Last updated: 2019-05-13Bibliographically approved

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