Pulping and papermaking properties of managed second-growth softwoods

Differences between the wood, fiber, and pulp properties of juvenile and mature wood of second-growth Douglas-fir, jack pine, and lodgepole pine have been quantified. Juvenile wood is less dense and is drier if it is heartwood but wetter if it is sapwood. Juvenile wood gives lower kraft pulp yields, but these pulps have finer fibers than those from mature wood, and give sheets that are denser, smoother, more extensible, and stronger in tensile. In mechanical pulping, juvenile wood requires more energy than does mature wood to refine to 100 mL CSF, but the finer-fibered juvenile wood pulps have superior light-scattering ability. The implications of these differences are discussed with reference to transportation cost, kraft pulping, mechanical pulping, and the production of specialty pulps. Application : the observed differences in the fiber properties of kraft and refiner mechanical pulps from juvenile and mature wood provide the potential for producing pulps with a range of properties by processing furnishes comprising different ratios of chips from juvenile and mature wood.