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Cellulose derivatisation – tuning and analysing the degree of substitution
University of Natural Resources and Life Sciences Vienna (BOKU).
University of Natural Resources and Life Sciences Vienna (BOKU).
University of Natural Resources and Life Sciences Vienna (BOKU).
University of Natural Resources and Life Sciences Vienna (BOKU).
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2016 (English)Conference paper, Oral presentation with published abstract (Other academic)
Abstract [en]

Pulp fibres are negatively charged by nature, but the resulting electrostatic repulsion can be changed by cationisation. This rather straightforward chemical modification will considerably broaden the application range of lignocellulosic materials, such as wood pulp fibres. The pulp fibres can be covalently modified with the same reagent that is widely used for the cationisation of starch, 2,3 epoxypropyltrimethylammonium chloride. In general, one option for the hydroxyalkylation of cellulose is in slurry processes with organic diluents.

Using different organic solvents, the cationisation efficiency as well as on the properties of pulp can be influenced easily. In the presented study, a bleached softwood Kraft pulp was cationised in alkaline mixtures of water with dimethyl sulfoxide (DMSO), isopropanol, and tetrahydrofuran (THF). Of the systems studied, THF offered the highest reaction efficiency with respect to the achieved degree of substitution (DS). The system with DMSO was the only one that considerably decreased the molar mass of the material; the reaction efficiency was similar to a purely aqueous system. Alkaline isopropanol had the greatest impact on crystallinity and while this system increased the reaction efficiency, it was still less effective than THF. Replacing 90% of the water with THF yielded a significanly higher DS. The DS linearly depended on the concentration of reagent in respect to the present water; this was observed not only for purely aqueous systems but also for systems that contained THF. This correlation may be deployed to plan and control laboratory-scale cationisation assays.

Tuning the DS as described above also calls for reliable analytical techniques for DS determination. The resulting materials with different DS were analysed by titration, infrared spectroscopy (IR), elemental analysis, and thermogravimetry. All the methods tested have their merits. While titration and elemental analysis are well-established reference methods with many published data, they require time-consuming pre-treatments. This can be avoided by fast and simple IR spectroscopy. However, IR spectroscopy relies on a reference method to quantify the DS. Another option explored in this work is thermogravimetry that yields additional information on water content and purity of the sample. This method, too, requires a reference method to evaluate the impact of the DS on the changed thermograms.

Place, publisher, year, edition, pages
2016.
National Category
Other Chemistry Topics
Identifiers
URN: urn:nbn:se:umu:diva-128500OAI: oai:DiVA.org:umu-128500DiVA, id: diva2:1052100
Conference
The 7th workshop on cellulose, regenerated cellulose and cellulose derivatives
Available from: 2016-12-05 Created: 2016-12-05 Last updated: 2016-12-05

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CiteExportLink to record
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Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
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  • de-DE
  • en-GB
  • en-US
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