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Licensed Unlicensed Requires Authentication Published by De Gruyter July 18, 2006

On the relationship between fibre length, cellulose chain length and pulp viscosity of a softwood sulfite pulp

Luc Lapierre, Jean Bouchard and Richard Berry
From the journal


Many chemical pulp mills use pulp viscosity as an indicator of pulp strength, and some mill customers stipulate a particular viscosity threshold for the delivered product. Nevertheless, the value of the viscosity-strength relationship is often questioned, particularly as it varies with the wood species and the pulping process. To provide some insight, the viscosity, degree of polymerisation and fibre length were measured for a bleached softwood sulfite pulp segregated into different fractions with respect to fibre length using a Bauer-McNett fractionator. It was demonstrated that fractions with a longer average fibre length also had a higher degree of polymerisation and higher viscosity. The cellulose chain length in chemical pulps is approximately three orders of magnitude shorter than the fibre length, and thus a relationship between these two properties should not be expected. The possible causes of the correlation between fibre length and viscosity are discussed. In this work, viscosity appears to be an indirect measurement of the average fibre length of a pulp, which would be the direct contributor to the strength of that pulp.


Corresponding author. Pulp and Paper Research Institute of Canada (PAPRICAN), 570 Boul. St-Jean, Pointe-Claire, Québec, Canada H9R 3J9


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Published Online: 2006-07-18
Published in Print: 2006-07-01

©2006 by Walter de Gruyter Berlin New York