Changes in accessibility of cellulose during kraft pulping of wood in deuterium oxide

•Cellulose microfibril aggregation occurs during the heat-up period of kraft pulping.•Hemicellulose dissolution promotes cellulose microfibril aggregation.•Increase in kraft cooking alkalinity increases cellulose microfibril aggregation. Fresh birch chips were treated with different concentrations o...

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Bibliographic Details
Published in:Carbohydrate polymers 2014-01, Vol.101, p.792-797
Main Authors: Pönni, Raili, Galvis, Leonardo, Vuorinen, Tapani
Format: Article
Language:English
Subjects:
Accessibility
Applied sciences
Birch
Cellulose - chemistry
Cellulose and derivatives
Cellulose microfibril
Deuteration
Deuterium oxide
Deuterium Oxide - chemistry
Exact sciences and technology
Hydrogen-Ion Concentration
Infrared spectroscopy
Kraft pulping
Natural polymers
Paper, paperboard, non wovens
Physicochemistry of polymers
Polymer industry, paints, wood
Pulp manufacturing
Sulfates - chemistry
Water retention value
Wood - chemistry
Wood. Paper. Non wovens
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Summary:•Cellulose microfibril aggregation occurs during the heat-up period of kraft pulping.•Hemicellulose dissolution promotes cellulose microfibril aggregation.•Increase in kraft cooking alkalinity increases cellulose microfibril aggregation. Fresh birch chips were treated with different concentrations of sodium hydroxide and sodium sulfide in deuterium oxide in typical kraft pulping conditions and the extent of irreversible deuteration of the chips/pulps was followed by Fourier transform infrared (FT-IR) spectroscopy. Water retention values (WRV) of pulps were measured to evaluate accessibility of cellulose. The kraft pulping with deuterium oxide led to significant proton-deuterium exchange that was not reversed when the chips/pulps were washed with water. The deuteration followed a first order dynamics with a maximum obtained in the beginning of delignification stage. Higher dosages of effective alkali resulted in a higher degree of deuteration and lower WRV. An inverse relationship between the extent of deuteration and WRV suggests that both were induced by cellulose microfibril aggregation. Results also indicate that hemicellulose dissolution plays an important role in the induction of cellulose microfibril aggregation, while lignin dissolution has less influence.
ISSN:0144-8617
1879-1344
DOI:10.1016/j.carbpol.2013.10.001