THE INFLUENCE OF WOOD AND FIBER PROPERTIES ON MECHANICAL PULPING

Wood properties and wood quality have a large impact on the manufactur e of mechanical pulps. Species density is known to influence the energ y requirements of pulping and the quality of the pulp produced. Low-de nsity softwoods such as spruces are favored raw materials. Wood densit y within a species also influences energy requirements and pulp qualit y, but in this case, higher density wood from mature trees is generall y preferred. To understand the anomalous behavior of wood density in r efining, it is necessary to consider how wood density varies between a nd within species, and to understand how energy is distributed to the wood in a disk refiner. Average fiber dimensions appear to control the energy required to create usable fiber surface area from the wood, bu t the variation in wood properties within the annual growth increment appears to control the way energy is distributed to the wood and the e fficiency of energy use in refining.