CLASSIFIED WOOD RAW-MATERIALS FOR DIVERSIFIED SOFTWOOD KRAFT PULPS

Twenty-nine different softwood kraft pulps were produced by classifyin g wood raw material, consisting of Pinus silvestris and Picea abies, a ccording to cambium age and growth rate. Wood properties as well as pr operties of pulp fibers and laboratory handsheets have been determined . There is a considerable variation in the properties of the pulp fibe rs. Fiber length and coarseness depend heavily on cambium age. Growth rate provides still more explanatory power in the case of Picea abies, but not in the case of Pinus silvestris. There is relatively little v ariation in fiber perimeter; thus the variation in coarseness is mainl y due to the thickness of I-he cell walls. It is difficult to influenc e microfibril angle and fiber strength by classifying wood raw materia ls.