Effects of Specific Gravity and Wood Chemical Content on the Pulp Yield of Loblolly Pine

Abstract

We quantified the effects of wood density (chip specific gravity) and wood chemical composition (cellulose, hemicellulose, and lignin) on the kraft pulp yield of 13-year-old loblolly pine trees (Pinus taeda) grown as part of a genetic selection study. Both bleachable (kappa No. 30) and linerboard grade (kappa No. 100) pulps were made from 18 trees selected for combinations of wood specific gravity and cellulose:hemicellulose:lignin ratios. Statistical analysis indicated that digester pulp yield correlated significantly with wood xylan content and cellulose-to-lignin ratio but was not strongly correlated to wood specific gravity. Near infrared (NIR) spectra were collected from wood samples and correlated with the total kraft pulp yields. The analyses for both kappa No. 30 and kappa No. 100 pulps provided strong calibration statistics, suggesting that papermakers can use NIR spectroscopy to esti-mate the bleachable and linerboard grade pulp yields of P. taeda whole-tree samples.

Mapping and modeling within-tree variation for loblolly pine pulp yield and lignin content

“…The number of factors recommended for both models corresponded to a clear minimum in explained variance and R cv 2 values continued to improve as the number of factors increased indicating that the models were not over-fitted. The pulp yield model compares well with that reported by White et al [64] that was based on the same dataset but used NIR spectra collected from a representative chip sample processed from the whole-tree samples (intact chips were analyzed by NIR when green, after drying and after milling). Figures 2 and 3 show pulp yield and lignin maps that represent the average of 18 loblolly pine trees at ages 13 and 22, respectively, with age-related trends of increasing pulp yield, and decreasing lignin apparent.…”

“…Note that the weighted average properties at lower height levels within each tree (such as the stump) represent a greater amount of the total area of the disks than the property at the tip of the tree. The calculated values were compared to measured values reported in White et al [64].…”

“…The revenue generated by the pulp and paper sector is significant; for example, in Georgia this sector generates 65% of the total forestry and forest products revenue [18]. Despite the importance of loblolly pine for Kraft pulp production, limited information exists for this species (and hardwood and softwood species in general) regarding within-tree variation of pulp yield and lignin content, two properties directly related to the economics of pulp production [21,64].…”

Extraction of Hemicellulose from Loblolly Pine Woodchips and Subsequent Kraft Pulping

“…All the pulp yields (∼52.0%) were close to the literature values of softwood linerboard grade pulps. 37 The pulp chemical composition analysis also showed the Klason lignin (∼ 14.5%) and glucose content (∼73.5%) were close in these three pulps.…”

“…The Kappa number of the final linerboard kraft pulp ranged 90−100. 37 The cooking conditions for the borate assisted alkaline extracted woodchips were alleviated by either decreasing the H-factor (by 30%) or reducing the EA/AA (by 25%), as indicated in Table 1. After cooking, the chips were disintegrated employing a heavy-duty blender and then screened on a 0.15 mm flat screen.…”