Effect of wood storage and seasonal variations of hardwoods on pulp and paper properties

Wood induced variations are one of the major causes of product quality fluctuations in the pulp and paper manufacture. Wood storage (time and form), seasonal variations are the factors that contribute to the variations in pulp and paper quality. However these variations are species specific. Maple, birch and aspen are the predominantly used hardwoods for pulp and paper production in Canada. In this thesis harvested maple, birch and aspen were stored in both round-wood and chip forms for three months during summer and winter to evaluate the changes in wood morphology, chemical composition and their effects on pulp and paper properties in reference to those of fresh chips.;It was found that the wood stored during summer showed higher losses in pulp yield when stored in both round-wood and chip forms, and the chip form was always higher than the round-wood form. Changes in cooking time were to be made between species and seasons, indicating the species dependency of wood in Kraft pulping. During summer storage there was no change in cooking time and chemical charge to produce pulp with the same kappa number, suggesting the delignification rate is not influenced by the wood storage. However for wood stored during winter, modification in cooking conditions had to be made. Loss in initial pulp freeness, generation of more fines fraction and a decrease in mean fiber length were also observed during seasons and storage. The greater loss in pulp yield and tear strength for wood stored in the chip form than in the round-wood form is because of the increased surface area available for wood deterioration. The effects on the maximum development of both burst and tensile were not significant.