Modeling Kraft Fiber Morphology and Paper Properties from Forest Data: The Example of Maritime Pine Thinning Logs, 2000 Pulping / Process & Product Quality Conference Proceedings

G. Chantre, D. Sens, O. Bongrand, A. Bouvet, E. Robin--In order to better adapt the pulpwood supply to the industrial needs and to enhance the papermaking potential of the maritime pine Kraft fibers, AFOCEL and industrial pulp mills of South West France wish to connect forest parameters (age of the plantation, diameter of the tree, height within the tree) to the fiber morphology and the paper properties.

Models are set up in order to link the Kraft fiber morphology to the wood structure, thus to simplify the assessment of pulp and paper characteristics. The modeling approach relies on two steps: firstly, a theoretical model based on within-ring wood samples, secondly a general model built at the « group of rings » level and based on a broader sampling basis (age, height, trees). The models which lead to the prediction of the average fiber morphology are based on the determination of cambium age, height, within-ring wood density traits and earlywood / latewood ratio, these parameters being easily assessed by X-ray micro-densitometry. The validation of the « fiber model » is made on a broad basis of stands, sites, trees, heights of sampling. The same approach is applied for modeling the paper properties. By analyzing the structure of the furnish wood, the Kraft paper properties of tear index, burst index, bulk density, breaking length, porosity can be predicted.

From the analysis of the X-ray micro-densitometry profiles of 600 maritime pine thinning logs, the influence of simple forest data on the fiber morphology and the paper properties can be determined. Controlling the average diameter of pulp logs on the wood yard allows to discriminate the pulp and paper properties in a limited range. The discrimination of the wood assortments is much more efficient when considering also the « tree level », especially the stand age and the girth at breast height. Simple charts are then delivered in order to help foresters to meet industrial requirements.