Quantification of water in different states of interaction with wood pulp fibres

Dissolving wood pulp (DWP) contains high levels of cellulose and has various applications. Production of dissolving wood pulp is accompanied by various challenges such as equipment operational problems and high bleaching costs. These are mainly due to lignin and other impurities contained in wood. Further, these impurities impose threats to the dissolving pulps applications such as the viscose process and the manufacture of finished rayon products. Removal of these contaminants at the early production stages proved effective in meeting by the challenges. Hydrocyclones achieve the separation of heavy and light pulp components in a process known as fractionation. In the case of dissolving wood pulp, hydrocyclones fractionate the pulp fibres into coarse fibres and fine fibres known as fines. Fines are the reject materials and are associated with impurities such as wood resins. Wood pulp was fractionated at 0.8% consistency using a Kadant laboratory hydrocyclone at mass reject rates of 5% and 11%. Pulp properties and application properties were determined and compared to unfractionated pulp. The fractionated pulps showed higher cellulose contents and lower levels of fines and associated resins. Bleaching of the fractionated pulps under a standard ODEDH bleaching sequence showed higher levels of delignification, as measured by brightness, and more favourable application properties. These findings were used to optimise the bleaching sequence by reducing the amount of chlorine dioxide applied in the second chlorine dioxide stage. The optimised bleaching sequence produced pulps with satisfactory fibre and application properties.

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The effect of cellulose degradation on the strength of wood pulp fibres

Nordic Pulp & Paper Research Journal ◽

10.3183/npprj-1992-07-03-p152-154 ◽

1992 ◽

Vol 7 (3) ◽

pp. 152-154 ◽

Cited By ~ 46

Author(s):

Norayr Gurnagul ◽

Derek H. Page ◽

Michael G. Paice

Keyword(s):

Cellulose Degradation ◽

Wood Pulp ◽

Pulp Fibres

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Distribution of strain to failure of single wood pulp fibres

Nordic Pulp & Paper Research Journal ◽

10.3183/npprj-2001-16-01-p046-056 ◽

2001 ◽

Vol 16 (1) ◽

pp. 46-56 ◽

Cited By ~ 12

Author(s):

Fredrik Thuvander ◽

E. Kristofer Gamstedt ◽

Per Ahlgren

Keyword(s):

Wood Pulp ◽

Pulp Fibres

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Surface Chemistry of Eucalyptus Wood Pulp Fibres: Effects of Chemical Pulping

Holzforschung ◽

10.1515/hf.2002.094 ◽

2002 ◽

Vol 56 (6) ◽

pp. 615-622 ◽

Cited By ~ 22

Author(s):

P. Fardim ◽

N. Durán

Keyword(s):

Contact Angle ◽

Surface Chemistry ◽

Surface Coverage ◽

Wood Pulp ◽

Work Of Adhesion ◽

Sodium Salts ◽

Tof Sims ◽

Eucalyptus Wood ◽

Chemical Pulping ◽

Pulp Fibres

Summary The surface chemistry of Eucalyptus grandis wood pulp fibres was investigated using the sessile drop apparent contact angle, XPS and TOF-SIMS techniques. Pulp fibres were studied using different chemical pulping conditions. The pulping affected the surface coverage of lignin and extractives, as indicated by XPS, and the work of adhesion with water, as estimated from contact angle determinations. The amount of surface lignin decreased while surface extractives and work of adhesion with water increased in relation to the amount of active alkali used in the pulping. Desorption and analysis of surface extractives by TOF-SIMS showed sterols, fatty acid calcium and sodium salts. After acetone extraction the spectra obtained by TOF-SIMS showed changes. However, calcium and sodium salts of fatty acids were still detected, indicating their resistance to solvent extraction. This resistance to extraction can affect the lignin and extractive surface coverage estimations using XPS due to the contribution of the carbon content after extraction. The extent of interference was, however, uncertain.

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