Importância relativa da densidade básica e da constituição química de madeira de Eucalyptus spp. no rendimento, branqueabilidade e qualidade da polpa kraft

• Autor(a) principal: Mokfienski, Alfredo
• Data de Publicação: 2004
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/519
• topic: Polpação kraft; Carboidratos; Xilanas; Kraft pulping; Carbohydrates; Xylan; CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL::TECNOLOGIA E UTILIZACAO DE PRODUTOS FLORESTAIS

Ten Eucalyptus wood from different species, ages, spacings and origins were transformed in to kraft pulp with kappa number 17-18 and bleached to 90% ISO brightness with the O-D-PO-D bleach sequence. The physical and chemical characteristics of the wood, brown pulps and bleached pulp samples were measured and evaluated. Wood fiber dimensions were optically measured using bleached fibers. The pulps were PFI refined and handsheets were made. The quality of the pulps (optical, hygroscopic and mechanical properties) was measured and compared. The results of the study were analyzed and statistically interpreted by means of regression and correlation analysis. No significant correlation was found between wood density and the total carbohydrate content. These two independent variables had small effect over organic and inorganic wood composition. In the pulping process, wood density had higher influence in the alkali charge requirement, wood consumption and in the oxygen- delignified pulp viscosity. Pulp yield, brown pulp viscosity, black liquor dry solid content and oxygen-delignification rate were more strongly affected by the wood carbohydrate content. The independent variables also affected bleached pulp coarseness while wood basic density affected the fiber width and lumen diameter. Air and stress resistance of bleached and refined pulps to 30 SRo (Schopper-Riegler) were affected by the independent variables while hygroscopic properties (water retention) were affected only by the wood density. Regression analysis of independent variables consisting of wood basic density and brown pulp hemicelulose content with mechanical properties of refined pulps did no indicate any significant influence. The results showed the need for consideration of some important parameters of the wood selection process for bleached kraft eucalypt pulp production, namely, wood basic density as well as total carbohydrate content, process yield, cellulose and hemicelluloses content.