Effects of Loblolly Pine Tree Age and Wood Properties on Linerboard Grade Pulp Yield and Sheet Properties. Part 1: Effects on Pulp Yield, 2010 TAPPI PEERS Conference

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This paper reports the results of a study of relationships of loblolly pine tree age and wood characteristics with the yield of pulp obtained when the trees were chipped and pulped by the kraft process. Eighteen 13-year old and eighteen 22-year-old loblolly pine trees were selected to represent specified ranges of specific gravity and lignin content. The trees were further characterized by chemical analysis and near-infrared (NIR) spectroscopy before being pulped by the kraft process. The resulting pulps were characterized by measurements of yield and chemical analysis. Multiple regression analysis was then used to identify wood characteristics that most influenced pulp yield and to derive equations relating pulp yield to tree age, specific gravity and wood chemical composition. In addition, NIR calibrations were developed to allow prediction of pulp yield from NIR analysis of wood. The results showed that wood specific gravity cannot be used to predict the yield of linerboard-grade pulp from trees of either age. The yield of pulp from 13-year-old trees can be predicted from the amounts of xylan and lignin present in the wood. The yield of pulp from 22-year-old trees decreased with increasing lignin content but was unrelated to their xylan content. Thirteen-year-old trees had significantly higher xylan content and the excess xylan was lost during pulping. The developed regression equations will allow estimation of pulp yields that can be expected from 13- and 22-year-old trees, given their contents of xylan and lignin.