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The porous structure of pulp fibres with different yields and its influence on paper strength
KTH, Superseded Departments, Fibre and Polymer Technology.ORCID iD: 0000-0001-8622-0386
2003 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 10, no 2, 111-123 p.Article in journal (Refereed) Published
Abstract [en]

The porous structure of the interior of papermaking fibres is a well-known important property of the fibres. Changes of this structure will influence tensile and burst strength of paper formed from the fibres and a change in pore size of the pores within the fibre wall is also important for the ability of molecules to diffuse in and out of the fibre wall. Relevant examples of this latter effect are the removal of lignin during cooking and the addition of performance chemicals during papermaking. In this paper, pore sizes and the pore size distribution of unbleached softwood fibres have been studied. A well-characterised fibre material consisting of laboratory cooked spruce and pine pulp of various lignin contents was used. Pore size and pore size distribution were measured by studies of the relaxation behaviour of H-2 in fibres saturated with (H2O)-H-2. Beside this the total and surface charge of the fibres were also measured together with strength properties of papers from unbeaten fibres. For both pulps, there is a maximum in pore radius at a yield around 46%. Calculations of fibre wall volume from water retention values and yield levels show that there is a discontinuity in pore radius as a function of the fibre wall volume around a yield of 51%. It is suggested that this discontinuity is caused by the breakdown of the hemicellulose/ lignin matrix within the fibre wall at this yield level. The strength of the papers formed from the fibres shows a correlation with the surface charge of the fibres. Based on the change in surface charge with yield and the change in total charge with yield, this correlation is suggested to be due to an opening up of the external part of the fibre wall. This stresses the importance of the chemical composition and physical structure of the outer layer of the fibre wall.

Place, publisher, year, edition, pages
2003. Vol. 10, no 2, 111-123 p.
Keyword [en]
charge, electrostatics, fibre wall volume, fibres, pore size distribution, pore size, softwood fibres, swelling, tensile strength, unbleached fibres, pore structure, nmr technique, cellulose fibers, integral-equations, saturation point, relaxation, water, wood, diffusion, gels
URN: urn:nbn:se:kth:diva-22658ISI: 000184046200003OAI: diva2:341356
QC 20100525Available from: 2010-08-10 Created: 2010-08-10Bibliographically approved

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Wågberg, Lars
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