A mathematical method for determining fiber wall thickness and fiber width.

APPLICATION: An accurate, cost-effective way to calculate the fiber cross-sectional dimensions can predict several of the properties of paper made from softwood kraft pulp.

The researchers have developed a method for calculating the fiber cross-sectional dimensions. Average values of the fiber wall thickness and the fiber width are derived based on measurements of fiber coarseness, pulp yield, and wood density. The wood density is used to distinguish between fibers with different ratios of wall area to lumen area. The fiber coarseness is used to distinguish between large-diameter fibers and small-diameter fibers. By combining wood density and fiber coarseness and by assuming that the density of the fiber wall is constant, the authors were able to deduce an exact mathematical expression for fiber wall thickness and fiber diameter.

The method was validated both by data found in the literature and by data from the researchers' trials. The calculated cross-sectional dimensions correlated well with several properties of handsheets made from softwood kraft pulp. The fiber cross-sectional dimensions influenced sheet density, tensile index, and tear index. For TMP, the fiber wall thickness had an effect on the light-scattering coefficient. View this paper online at http://www.tappi.org/index.asp?pid=28649

Knut Roar Braaten is with Norske Skog Research, P. O. Box 66, Centrum, N-3701 Skien, Norway. Dag Molteberg is with Sodra Cell R & D, P. O. Box 83,N-3481 Tofte, Norway. Email Molteberg at [e-mail]