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The influence of high temperature on the ageing of cellulose impregnated with metal chlorides under dry and moist conditions.
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik. (FSCN – Fibre Science and Communication Network)
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik. (FSCN - Fibre Science and Communication Network)
Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
Ansvarig organisation
2005 (Engelska)Ingår i: Proceedings, 13th International Symposium on Wood, Fibre and Pulping Chemistry, 16-19 May, Auckland, New Zealand, 2005, s. 243-249Konferensbidrag, Publicerat paper (Övrigt vetenskapligt)
Abstract [en]

Cellulose sheets impregnated with metal chlorides were treated at high temperatures in either a dry or a humid environment. The influence of Mg2+, Ca2+ and Fe3+ on the heat-induced discolouration and on the viscosity of cellulose was investigated. Addition of metal ions to cellulose sheets did not significantly influence the colour of the un-aged sheets. At 120 and 150C there are only small increases in the discolouration during heat-ageing. The samples with iron are somewhat more discoloured than the others. After 3,5 hours at 150C Mg2+ also showed an increased discolouration. When the sheets are aged at 180C for short time no large difference between the cellulose reference and the metal impregnated cellulose can be observed. After longer time there is a significant discolouration caused by Ca2+ and Mg2+. Samples with Ca2+ and Mg2+ are 4 and 10 times, respectively, more discoloured than cellulose reference and cellulose impregnated with Fe3+. Under humid conditions at 180C and after 30 minutes Ca2+ and Mg2+ impregnated cellulose are more discoloured than the cellulose reference and the Fe3+ impregnated cellulose. Moisture more than doubles the effect of temperature. pH has no large influence on the discolouration of the cellulose but acid in combination with Mg2+ increases the discolouration 20 times compared to the un-aged reference. The k-values are related to the amount of chromophore formed during ageing. The largest increase in k-values was observed at 285 nm, which was due to the formation of 5-hydroxymethyl-2-furaldehyde (HMF) from wood hexoses formed during hydrolysis of cellulose. Mg2+ and Ca2+ caused a large decrease in DP and increased formation of HMF, compared to the cellulose reference with subsequent formation of chromophores upon heating.

Ort, förlag, år, upplaga, sidor
2005. s. 243-249
Nyckelord [en]
Cellulose, Heat-induced ageing, High temperature, Metal ions, UV/VIS spectroscopy, DP
Nationell ämneskategori
Kemiteknik
Identifikatorer
URN: urn:nbn:se:miun:diva-2894Lokalt ID: 2548ISBN: 0-9585548-9-7 (tryckt)OAI: oai:DiVA.org:miun-2894DiVA, id: diva2:27926
Konferens
13th International Symposium on Wood, Fibre and Pulping Chemistry, 16-19-May, 2005, Auckland, New Zealand
Tillgänglig från: 2008-09-30 Skapad: 2009-06-08 Senast uppdaterad: 2014-04-24Bibliografiskt granskad

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Logenius, LouiseFriman, LindaAgnemo, Roland

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