IMPORTANCE OF CROSS-DIMENSIONAL FIBER PROPERTIES AND COARSENESS FOR THE CHARACTERIZATION OF SOFTWOOD SULFATE PULP

This article examines the suitability of coarseness for the characterisation of cross-dimensional fibre property variations and discusses possibilities of predicting the papermaking potential of softwood sulphate pulp by means of the coarseness value. In addition a practical method for coarseness determination is presented. The results show that coarseness is in practice the best way to characterise the papermaking potential of different softwood fibres, although thick-walled, narrow, stiff and strong fibres can have the same coarseness as thin-walled wide fibres with large lumen and excellent bonding properties. This is due to the following facts: first the cell wall thickness alone explains most of the coarseness variation, and second, the cell wall thickness (coarseness) plays a more important role than fibre length when predicting the papermaking potential of different softwood fibres. Coarseness alone explained over 80% of the total variation in tensile and tear strength of different European and American conifers. Coarseness was also shown to explain over 70% (significant at the 99% confidence level) of the variation in apparent sheet density and air resistance. Addition of the fibre length to the coarseness model did not have any statistically significant effect on the paper properties.