Modifying kraft pulping to produce a softwood pulp requiring less energy in tissue paper production

Modification of softwood kraft pulp by the addition of either polysulfide (PS) or sodium borohydride (NaBH4) has been shown to increase the pulp yield due to a higher retention of glucomannan.  The pulps with higher yield gave a paper with higher tensile index than reference pulp, especially at lowe...

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Main Author: Rahman, Hafizur
Format: Others
Language:English
Published: Mittuniversitetet, Avdelningen för kemiteknik 2018
Subjects:
Online Access:http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-32833
http://nbn-resolving.de/urn:isbn:978-91-88527-42-4
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spelling ndltd-UPSALLA1-oai-DiVA.org-miun-328332018-02-13T05:09:52ZModifying kraft pulping to produce a softwood pulp requiring less energy in tissue paper productionengRahman, HafizurMittuniversitetet, Avdelningen för kemiteknikSundsvall : Mid Sweden University2018Modifying kraft pulptissue dewateringpolysulfidesodium borohydridetensile indexhemicelluloseEngineering and TechnologyTeknik och teknologierModification of softwood kraft pulp by the addition of either polysulfide (PS) or sodium borohydride (NaBH4) has been shown to increase the pulp yield due to a higher retention of glucomannan.  The pulps with higher yield gave a paper with higher tensile index than reference pulp, especially at lower degrees of refining. The higher yield pulps also showed a greater porosity of the fibre wall, indicating an increase in the swelling potential of the fibres. This can lead to increased fibre flexibility and increased joint strength between the fibres and to the higher handsheet tensile index. However, the swelling increase associated with the higher hemicellulose content could also make dewatering more challenging because of the higher water retention of the pulp. The results of this study show however that the positive influence of the increase in yield (fewer fibres and a more open sheet structure) dominates over the negative influence of the higher hemicellulose content on the dewatering properties, especially at lower refining energy levels. Studies simulating full-scale tissue machine dewatering conditions showed that pulps with a higher yield and a higher hemicellulose content had a higher tensile index at the same dryness. Moreover, the same dryness level was achieved in a shorter dwell-time. A given tensile index was also achieved with less refining energy. Increasing the yield and hemicellulose content by the addition of either an oxidizing or a reducing agent in the softwood kraft pulping process thus has a potential for giving high quality fibres for tissue paper production with less refining energy and lower drying energy costs.   <p>Vid tidpunkten för framläggningen av avhandlingen var följande delarbeten opublicerade: delarbete 2 inskickat.</p><p>At the time of the defence the following papers were unpublished: paper 2 submitted.</p>Licentiate thesis, comprehensive summaryinfo:eu-repo/semantics/masterThesistexthttp://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-32833urn:isbn:978-91-88527-42-4Mid Sweden University licentiate thesis, 1652-8948 ; 137application/pdfinfo:eu-repo/semantics/openAccess
collection NDLTD
language English
format Others
sources NDLTD
topic Modifying kraft pulp
tissue dewatering
polysulfide
sodium borohydride
tensile index
hemicellulose
Engineering and Technology
Teknik och teknologier
spellingShingle Modifying kraft pulp
tissue dewatering
polysulfide
sodium borohydride
tensile index
hemicellulose
Engineering and Technology
Teknik och teknologier
Rahman, Hafizur
Modifying kraft pulping to produce a softwood pulp requiring less energy in tissue paper production
description Modification of softwood kraft pulp by the addition of either polysulfide (PS) or sodium borohydride (NaBH4) has been shown to increase the pulp yield due to a higher retention of glucomannan.  The pulps with higher yield gave a paper with higher tensile index than reference pulp, especially at lower degrees of refining. The higher yield pulps also showed a greater porosity of the fibre wall, indicating an increase in the swelling potential of the fibres. This can lead to increased fibre flexibility and increased joint strength between the fibres and to the higher handsheet tensile index. However, the swelling increase associated with the higher hemicellulose content could also make dewatering more challenging because of the higher water retention of the pulp. The results of this study show however that the positive influence of the increase in yield (fewer fibres and a more open sheet structure) dominates over the negative influence of the higher hemicellulose content on the dewatering properties, especially at lower refining energy levels. Studies simulating full-scale tissue machine dewatering conditions showed that pulps with a higher yield and a higher hemicellulose content had a higher tensile index at the same dryness. Moreover, the same dryness level was achieved in a shorter dwell-time. A given tensile index was also achieved with less refining energy. Increasing the yield and hemicellulose content by the addition of either an oxidizing or a reducing agent in the softwood kraft pulping process thus has a potential for giving high quality fibres for tissue paper production with less refining energy and lower drying energy costs.   === <p>Vid tidpunkten för framläggningen av avhandlingen var följande delarbeten opublicerade: delarbete 2 inskickat.</p><p>At the time of the defence the following papers were unpublished: paper 2 submitted.</p>
author Rahman, Hafizur
author_facet Rahman, Hafizur
author_sort Rahman, Hafizur
title Modifying kraft pulping to produce a softwood pulp requiring less energy in tissue paper production
title_short Modifying kraft pulping to produce a softwood pulp requiring less energy in tissue paper production
title_full Modifying kraft pulping to produce a softwood pulp requiring less energy in tissue paper production
title_fullStr Modifying kraft pulping to produce a softwood pulp requiring less energy in tissue paper production
title_full_unstemmed Modifying kraft pulping to produce a softwood pulp requiring less energy in tissue paper production
title_sort modifying kraft pulping to produce a softwood pulp requiring less energy in tissue paper production
publisher Mittuniversitetet, Avdelningen för kemiteknik
publishDate 2018
url http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-32833
http://nbn-resolving.de/urn:isbn:978-91-88527-42-4
work_keys_str_mv AT rahmanhafizur modifyingkraftpulpingtoproduceasoftwoodpulprequiringlessenergyintissuepaperproduction
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