Differences in Juvenile Pinus taeda (Loblolly Pine) Grown in Santa Catarina, Brazil and the Southern United States, 2009 TAPPI Engineering, Pulping, Environmental Conference

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An unbleached kraft mill in Santa Catarina State of Brazil has employed rapidly grown Pinus taeda tops and saw mill residuals in the production of high-yield kraft pulp for many years. Even though this pulp consists entirely of juvenile wood, it produces high quality, high yield kraft fiber. However, when this wood is pulped to bleachable grade kappa numbers, it produces low strength, low quality pulp as compared to juvenile P. taeda obtained from the Southern United States. Additionally, structural lumber produced from these trees exhibit inferior strength properties as compared to lumber produced from juvenile wood harvested in the Southern United States. The main differences between the wood grown in Santa Catarina, Brazil and in the Southern United States is the age of the tree at harvest and the ratio of early wood to late wood present in the tree. These differences result in a significant difference in wood specific gravity and in the microfibril angle in the S2 layer of the trachead. Several literature sources along with various laboratory studies were used to determine the specific aspects of juvenile wood that results in these strength differences. Comparisons between juvenile P. taeda grown in the Southern United States and in Brazil were employed to determine why bleachable grade juvenile pulps produced in the United States have reasonable strength properties while the bleachable grade juvenile pulp made from Brazilian trees exhibits poor strength properties.