Chemical characteristics and Kraft pulping of tension wood from Eucalyptus globulus labill

Abstract

-Tension (TW) and opposite wood (OW) of Eucalyptus globulus trees were analyzed for its chemical characteristics and Kraft pulp production. Lignin content was 16% lower and contained 32% more syringyl units in TW than in OW. The increase in syringyl units favoured the formation of β-O-4 bonds that was also higher in TW than in OW (84% vs. 64%, respectively). The effect of these wood features was evaluated in the production of Kraft pulps from both types of wood. At kappa number 16, Kraft pulps obtained from TW demanded less active alkali in delignification and presented slightly higher or similar pulp yield than pulps made with OW. Fiber length, coarseness and intrinsic viscosity were also higher in tension than in opposite pulps. When pulps where refined to 30°SR, TW pulps needed 18% more revolutions in the PFI mill to achieve the same beating degree than OW pulps. Strength properties (tensile, tear and burst indexes) were slightly higher or similar in tension as compared with opposite wood pulps. After an OD 0 (EO)D 1 bleaching sequence, both pulps achieved up to 89% ISO brightness. Bleached pulps from TW presented higher viscosity and low amount of hexenuronic acids than pulps from OW. Results showed that TW presented high xylans and low lignin content that caused a decrease in alkali consumption, increase pulp strength properties and similar bleaching performance as compared with pulps from OW.Keywords: Eucalyptus globulus, Reaction wood, Kraft pulping, Xylans and Lignin structure. CARACTERÍSTICAS QUÍMICAS E POLPAÇÃO KRAFT DE MADEIRA DE TRAÇÃO DE Eucalyptus globulus LABILL

Variation of Wood Pulping and Bleached Pulp Properties Along the Stem in Mature Eucalyptus globulus Trees

“…Target ISO brightness was 90% (mean 89.3% ±1.6 for all samples). The intrinsic viscosity of the pulps was low compared to the 942 to 1274 mL.g -1 reported by Santos et al (2008), but similar to the 821 mL g -1 in Aguayo et al (2012) for E. globulus pulps. The mean amount of ClO2 consumed (as active chlorine) was 4.8%, with variations due to the different initial kappa number of the unbleached pulps (Table 1).…”

The effect of eucalypt tree overaging on pulping and paper properties

“…The small difference in residual lignin between heartwood and sapwood pulps (11.2 vs. 9.5 for corrected Kappa number) may be explained by some cell wall waterproofing from the heartwood extractives decreasing liquor penetration and increasing chemical consumption (Hillis 1987;Gutiérrez et al 2001;Rowell et al 2005). The intrinsic viscosity of the pulps was slightly lower compared to the 942-1274 cm 3 /g reported by Santos et al (2008) but similar to the 821 cm 3 /g reported by Aguayo et al (2012) for E. globulus pulps. The kraft pulps produced from the overaged samples develop bleaching in a similar way to the industrial wood chips.…”

Investigating the molecular underpinnings underlying morphology and changes in carbon partitioning during tension wood formation in Eucalyptus

“…increasing wood flexibility and tolerance to mechanical perturbations). The relative reduction of xylan in tension wood and the increase in α‐cellulose are consistent with the generally accepted model of physicochemical changes in tension wood, but do not agree with previous tension wood physicochemical characterizations of E. globulus that showed an increase in xylan and no change in cellulose (Aguayo et al ., , ), although a reduction in lignin is consistently found.…”