Caracterização da madeira de tração em Eucalyptus grandis e sua influência na produção de polpa celulósica

• Ano de defesa: 2004
• Autor(a) principal: Sousa, Leonardo Chagas de
• Orientador(a): Lucia, Ricardo Marius Della
• Banca de defesa: Oliveira, José Tarcisio da Silva , Gomide, José Lívio , Vital, Benedito Rocha , Maciel, Antonio da Silva
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Ciência Florestal
• Departamento: Manejo Florestal; Meio Ambiente e Conservação da Natureza; Silvicultura; Tecnologia e Utilização de
• País: BR
• Palavras-chave em Português: Eucalyptus grandis; Madeira de tração; Celulose kraft
• Palavras-chave em Inglês: Eucalyptus grandis; Tension wood; Kraft pulp
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL
• Link de acesso: http://locus.ufv.br/handle/123456789/3057

The reaction wood in broadleaved tress, usually called tension wood, is found on the top side of stems and branches, causing them to reorient themselves by longitudinal shrinkage. It is characterized by a high proportion of cellulose and low of lignin, when compared to normal wood. The fibers usually show an abnormally thick wall, called gelatinous layer, on the inside of the secondary wall. Due to its effect on wood properties, reaction wood may be considered a serious problem in cellulose manufacture and also for the industry of solid wood products. This study had the objective of characterizing tension wood in Eucalyptus grandis and of evaluating its effect on cellulose production. Three inclined trees were chosen, harvested and cross-cut in 1.0 m long logs, from the bottom of the trees up to the first branch. Results showed that the tension wood in the trees had higher specific gravity and higher shrinkage values. The chemical composition also changed, with a smaller percentage of lignin and of extractives. Anatomically, it was found that the fiber width remained the same as that in normal wood, although its wall thickness increased due to the gelatinous layers. The fibers are also significantly longer. The vessels found in tension wood were smaller and less frequent. As to pulping, it was found that tension wood required a smaller quantity of chemicals to reach a prescribed kappa number. This is due to the low lignin concentration. The viscosity of pulp from tension wood was the same as that of normal wood, this indicating that the degree of polymerization is lower in tension wood, seeing that less pulping chemicals were used. A very important finding was that the yield was significantly higher in pulping tension wood, mostly due to the presence of the gelatinous layer. The yield for normal wood was 49%, while that for tension wood reached about 58%.