Estudos da polpação kraft, branqueamento e refino de eucalyptus grandis x eucalyptus urophylla

• Autor(a) principal: Favaro, Jaqueline Silveira Comelato [UNESP]
• Data de Publicação: 2015
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/132735; http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/11-12-2015/000855548.pdf
• topic: Polpação alcalina por sulfito; Lignina; Madeira - Quimica; Branqueamento; Sulphite pulping process

The eucalyptus kraft industry in Brazil has great importance for the sectors economy. The alkali charge and temperature parameters must be controlled during the kraft pulping and optimized in order to obtain high quality and high yield pulp. The refining is the process that consumes most energy in the mill and should be well controlled to the capital reduction. Thus, the aim of this study is to evaluate the influence of alkali load and final temperature of eucalyptus kraft pulping on refining and bleachability. Eucalyptus grandis x E. urophylla chips were characterized and cooked to different temperatures of 155 °C, 160° and 165 °C, and for each of them, the alkali charge that was applied to obtain pulps with a kappa number of 13, 15 and 17. Subsequently, part of the samples was bleached by the sequence OAHTD(Ep)D. Both bleached and unbleached pulps were refined in PFI mill and physical and mechanical tests were performed. This work is divided into four chapters, namely: (1) evaluation of temperature, alkali charge and its influence on fiber fractionation, refining and physical-mechanical testing; (2) the impact of the pulping parameters on its bleachability and refining; (3) the potential of a short sequence bleaching, AHTDP, of kraft eucalyptus pulp to 90% ISO brightness; (4) analysis of the chemical composition of the residual lignin in kraft eucalyptus pulp by nitrobenzene oxidation and nuclear magnetic resonance (NMR). The main conclusions of these chapters are: Chapter 1: lower cooking temperatures are beneficial to the cooking performance, selectivity, viscosity, and preservation of xylans. The use of low alkalinity in pulping increased the mechanical strength of the paper due to better preservation of carbohydrates; the final cooking temperature did not affect the refining with the same intensity as the alkali charge; Chapter 2: higher ... (Complete abstract click electronic access below)