PULP PRODUCED WITH WOOD FROM Eucalyptus TREES DAMAGED BY WIND

Abstract

Wind may damage eucalyptus trees, especially 24 months after planting, which can reduce wood fiber quality and hinder pulp production. The objective of this study was to evaluate the use of these materials in mixtures with wood from seven-yearold trees to produce pulp. Bleached pulp was produced using 100, 95, 85, 75 and 0% wood from seven-year-old eucalyptus trees, related to cutting age. Wood from two-yearold trees, when trees are most susceptible to damage by wind, completed each treatment. A 5 cm thick disc was taken from breast height (1.3m) on each tree for anatomical and ultrastructural characterization. The seven-year-old wood had lower vessel frequency and fibers with a longer length, higher cell wall fraction, higher modulus of elasticity and hardness, and a lower microfibril angle. Pulp refining decreased the opacity and specific volume, increased air resistance and improved mechanical properties. The addition of two-year-old wood to produce pulp reduced the mechanical properties and opacity, and increased the air resistance of the paper. The proportion of two-year-old wood that can be used in pulp production varied with the clone, parameter, and refining level. However, the pulp produced with 5% wood from two-year-old trees and 95% wood from sevenyear-old trees was similar to that with 100% seven-year-old wood. Therefore, 5% twoyear-old wood can be used to produce pulp without quality losses. PRODUÇÃO DE POLPA CELULÓSICA COM MADEIRA DE ÁRVORES DEEucalyptus DANIFICADAS PELO VENTO RESUMO: Árvores de eucalipto de rápido crescimento podem ser danificadas por ventos, principalmente 24 meses após o plantio, mas a baixa qualidade das fibras dessa madeira dificulta a produção de polpa celulósica. O objetivo deste estudo foi avaliar a utilização destes materiais para a fabricação de polpa celulósica em misturas com madeira de árvores de sete anos de idade. Polpa celulósica branqueada foi produzida com 100, 95, 85, 75 e 0% de madeira de árvores de dois clones de Eucalyptus grandis x Eucalyptus urophylla com sete anos de idade, relacionada com a idade de corte. Madeira de árvores de dois anos de idade, mais susceptíveis a danos por ventos, foi utilizada para completar cada tratamento. Um disco de espessura de 5 cm foi retirado na altura do peito (1,3 m) em cada árvore para a caracterização anatômica e ultra-estrutural. As árvores com sete anos apresentaram maior frequência de vasos, fibras com maior comprimento, fração parede, módulo de elasticidade e dureza e menor ângulo microfibrilar. O refino nas polpas diminuiu a opacidade e o volume específico e aumentou a resistência a passagem do ar e as propriedades mecânicas. A adição de madeira de dois anos de idade na produção de polpa celulósica reduziu a resistência mecânica e opacidade e aumentou a resistência à passagem de ar. A proporção da madeira de dois anos de idade, que pode ser utilizado na produção de polpa celulósica variou com o clone, parâmetro avaliado e intensidade do refino. No entanto, a polpa celulósica produzida com 5% de madeira de do...

The Effects of Alkaline Filtrate Recirculation Towards the Properties of Long Fiber Pulps With Od(epo)ded Bleaching Sequence

“…This also occurred with drainage, because the greater connection numbers hamper the water passing through the pulp (Gharehkhaniaet al, 2015). This behavior was reported for cellulose pulp from grasses (Andrade e Colodette, 2016), softwoods Chen et al, 2017) and hardwoods (Zanuncio et al, 2016).…”

“…The softwood tear index was reduced, even at low levels of refinement, as reported for Pinus massonianae and China Fir . In hardwoods, the tear index increased at the initial refinement levels due to the increase of connections and decreased at more intense refinement levels due to fiber degradation (Gharehkhania et al, 2015), as reported for Corymbia citriodora (Severo et al, 2013) and Eucalyptus grandis × Eucalyptus urophylla (Zanuncio et al, 2016).…”

Post-O2 Eucalyptus Pulp in a/D(ep)dp Bleaching Sequence Washed With Recirculation of the Alkaline Filtrate

“…T h e h i g h e r o r g a n i c a l o g e n s ( O X ) concentration of the pulp, increased by 36.7% compared to the control with the addition of the carryover, was due to the increased ClO 2 consumption during bleaching. These values were still acceptable for ECF pulp (< 200 gClt -1 ) as those below 30 gClt -1 of OX were suitable for ECF light processes (Sixta 2006).…”

“…The increased in the compounds oxidised by permanganate and resulted in a kappa number of 2.2 and final brightness of 87.2% ISO. The higher H 2 SO 4 load in the acid hydrolysis stage A (Table 1) of the pulps in relation to the control sequence was due to the carryover alkalinity (Sixta 2006). The increased in pH negatively impacted the chlorine dioxide stage and increased its consumption (Sevastyanova et al 2012, Ferraz & Ventorim 2018.…”

“…The filtrate recirculation returned the residual lignin and extractives to the system (Sixta 2006, He et al 2018. The increased in the compounds oxidised by permanganate and resulted in a kappa number of 2.2 and final brightness of 87.2% ISO.…”