Forest Products Laboratory

Title: Small-diameter trees used for chemithermomechanical pulps.

Author: Myers, Gary C.; Barbour, R. James; AbuBakr, Said M.

Date: 2003

Source: Gen. Tech. Rep. FPL-141. Madison, WI : U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory, 2003. 12 pages.

Station ID: GTR-FPL-141

Description: To restore and maintain forest ecosystem health and function in the western interior of the United States, many small-diameter stems need to be removed from densely stocked stands. In general, these materials are underutilized. Information on the properties of these resources is needed to help forest managers understand when timber sales are a viable option to accomplish ecosystem management objectives. Providing proof that this small-diameter material yields quality pulp would help increase its value and therefore help remove it from the forest. This study examines the acceptability of the small-diameter resource as a raw material for high-yield chemithermomechanical pulping (CTMP), which has the potential for improved fiber characteristics and paper strength compared with those of thermomechanical pulping (TMP). Pulps using CTMP were prepared from lodgepole pine and mixed Douglas-fir/western larch sawmill residue chips; lodgepole pine, Douglas-fir, and western larch submerchantable logs; and lodgepole pine, Douglas-fir, and western larch small trees. These small-diameter pulps were compared with commercially obtained sawmill residue chips of a Douglas-fir/western larch mixture and lodgepole pine. These pulps were also evaluated to see if CTMP improved the properties of the final product compared with products made using TMP. Compared with the controls, the CTMP prepared from Douglas-fir and lodgepole pine small trees and Douglas-fir submerchantable logs consumed more electrical energy during pulp preparation and had higher paper strength properties and lower optical properties. Also compared with the controls, lodgepole pine submerchantable logs consumed about the same electrical energy and had marginal strength properties and higher optical properties. Western larch submerchantable logs and small trees had the lowest electrical energy consumption of all pulps tested, low strength properties, but some of the higher optical properties. Western larch submerchantable logs and small trees appear to be unsuitable for CTMP. For the majority of the materials, CTMP improved the properties of the final product compared with corresponding TMP.

Keywords: Western softwoods, lodgepole pine, Douglas-fir, western larch, small-diameter trees, mechanical pulping, chemithermomechanical pulping, CTMP, pulp properties, paper properties.

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Citation

Myers, Gary C.; Barbour, R. James; AbuBakr, Said M.  2003.  Small-diameter trees used for chemithermomechanical pulps..   Gen. Tech. Rep. FPL-141. Madison, WI : U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory, 2003. 12 pages..