Upgrading of paper grade pulps to dissolving pulps by nitren extraction: yields,molecular and supramolecular structures of nitren extracted pulps |
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Authors: | Ron Janzon Jürgen Puls Andreas Bohn Antje Potthast Bodo Saake |
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Affiliation: | (1) vTI, Institute of Wood Technology and Wood Biology, 21031 Hamburg, Germany;(2) Fraunhofer Institute for Applied Polymer Science, 14406 Potsdam, Germany;(3) Department of Chemistry, University of Natural Resources and Applied Life Sciences, 1190 Vienna, Austria |
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Abstract: | Different paper grade pulps were extracted with nitren in order to produce dissolving pulps and polymeric xylan. The yield and molecular structure of the extracted pulps were investigated by carbohydrate analysis and HPSEC combined with fluorescence labelling in order to additionally monitor the carbonyl and carboxyl group profiles of the pulps. The supramolecular structure of selected pulps were further studied by solid state 13C-CP/MAS-NMR and wide-angle X-ray scattering (WAXS). These supramolecular data of nitren extracted pulps were compared to samples extracted with NaOH and a conventional dissolving pulp in order to classify the properties of nitren extracted pulps. Nitren extraction results in selective xylan removal without noticeable degradation or oxidation of the cellulose fraction. The resulting dissolving pulps have high molar masses, a narrow molar mass distribution and the typical contents of carbonyl and carboxyl groups. The supramolecular structure of cellulose is less affected by nitren compared to strong NaOH, and the resultant dissolving pulps still have the cellulose I structure. All laboratories are members of the European polysaccharide network of excellence EPNOE. |
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Keywords: | Nitren extraction Dissolving pulp HPSEC Carbonyl groups Carboxyl groups 13C-CP/MAS-NMR WAXS |
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