Evaluation of the APMP process for mature and juvenile loblolly pine

The wood cost of loblolly pine is lower than that of northern softwoods due to its fast growth rate and suitability for plantation harvesting. However, loblolly pine thermomechanical pulp (TMP) is difficult to bleach to high brightness. It also requires considerable refining energy to develop fibers, which limits its use mainly to low-value-added papers. We evaluated the potential for using the alkaline peroxide mechanical pulping (APMP) process for both mature and juvenile loblolly pine, with reference to the TMP process. Results of black spruce APMP were also used for comparison. In pilot plant trials, the APMP process, compared to theTMP process, required less specific refining energy and fewer bleaching chemicals to reach a given strength and brightness, and it produced a pulp with much lower shives content. For mature loblolly pine, 80%+ brightness was obtained with APMP, while the bleached TMP had a brightness ceiling of 76.6% ISO. The APMP process had more effect on juvenile pine than on mature wood with regard to pulp properties, and is therefore more beneficial for use with juvenile loblolly pine to maximize strength. In general, the APMP process is a technically viable method for dark and coarse fiber species such as loblolly pine because of the reduced amount of refining energy and bleaching chemicals required to reach a given strength and brightness. Application: This research may help mills lower fiber costs for higher brightness papers.