Characterization of Cypress Wood for Pulp Production

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Wood samples from Cupressus arizonica, Cupressus lusitanica, and Cupressus sempervirens were evaluated in terms of chemical, anatomical and pulp features in order to consider as raw-material for pulp production. Two 17-year-old trees per species were harvested and wood samples taken at two stem height levels (ground level and 2 m from the ground). Extractives and Klason lignin content were determined in the different wood samples. Wall thickness and tracheid diameter were determined for earlywood and latewood. Representative Wood chips from Pinus pinaster grown in Portugal and from Pinus sylvestris grown in Finland were used as references.
The average extractives content of the cypress woods was 3.9%, 3.3% and 2.5 %, respectively for C. lusitanica, C. sempervirens and C. arizonica. These values are lower than the corresponding values for the reference pines species (5.1 % for P. pinaster and 4.5 % for P. sylvestris). Klason lignin content ranged from 33 % to 36 % and was markedly higher than the values exhibited by the pinewoods (28.5 - 29.1 %).

Eucalyptus globulus and Pinus pinaster are the only hardwood and softwood used by the Portuguese pulp and paper industry. E. globulus is exploited in the production of bleached kraft pulps and transformed, generally, to office paper. Unbleached P. pinaster kraft pulps are obtained and converted, often to kraft liner and packaging paper.
Tree species diversification in the raw-material supply for forest-based industries is an acknowledged goal that could positively contribute to global forest sustainability, biodiversity and adaptation to climatic changes and natural hazards.
The environmental problems resulting from increasing world consumption of paper has stimulated research into t...

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...rom C. sempervirens has lower Klason lignin content and fibre characteristics that appear to be better suited for pulp and paper. The data on fibre characteristics reveals a very high variability.
2. The results showed that the wood samples from Cupressus exhibit lower yield and higher residual lignin content than the Pinus samples used. However with older trees this disadvantage could be overcome. Moreover, the P. sylvestris exhibits a slightly higher pulp yield than P. pinaster. As expected, chemical composition justifies the majority of the cooking results.
3. Some of the less favourable characteristics could be improved by using older trees. A more systematic study on the wood variability of different Cupressus species is therefore necessary to complement the knowledge on this raw material and assess its potential value for several uses as long fibre softwood.

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