Avaliação das propriedades físico-mecânicas de polpas produzidas por novas sequências de branqueamento.

Pedrazzi, Cristiane; Colodette, Jorge Luiz; Oliveira, Rubens Chaves de; Muguet, Marcelo Coelho dos Santos; Gomide, José Lívio

doi:10.5902/198050981766

Cited by 7 publications

(2 citation statements)

References 2 publications

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“…An increasing of delignification and reducing of kappa promotes higher pulp degradation, which results the production of pulp with higher fines from fibers fragmentation and lower viscosity (Shin and Strömberg 2007;Pedrazzi et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Effect of Kappa Number Variation on Modified Pulping of Eucalyptus

Segura¹,

Santos²,

Sarto³

et al. 2016

BioResources

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This work evaluated the impact of brownstock pulp kappa number variations on modified pulping process, oxygen delignification, bleaching, and the physical characteristics on bleached pulp. Wood chips of 6-yearold Eucalyptus grandis x Eucalyptus urophylla from Brazil were used. A modified pulping process was performed with the purpose of achieving two delignification levels on brownstock pulp: kappa 18 and kappa 15. Pulps were submitted to oxygen delignification and elemental chlorine-free (ECF) bleaching to achieve 89.5 ± 0.5% of ISO brightness. Subsequently, pulps were refined in four levels (0, 750, 1500, and 3000 rotations) for physical mechanical tests. Delignification increased after increasing the cooking H factor and alkali charge. As a result, delignification negatively impacted the pulping yields (from 56.1% to 55.0%) and the pulp viscosity (from 1,317 cm³/g to 1,227 cm³/g). Pulps with an initial kappa of 15 presented more efficient oxygen delignification and lower consumption of bleaching reagents. The final viscosity of these pulps were lower (899 cm³/g against 963 cm³/g), however, than that of the pulps with an initial kappa of 18. Furthermore, the pulps with a higher unbleached kappa demanded less refining energy and had lower capillarity. The other physical properties were not influenced by the brownstock delignification level.

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Section: Introductionmentioning

confidence: 99%

Effect of Kappa Number Variation on Modified Pulping of Eucalyptus

Segura¹,

Santos²,

Sarto³

et al. 2016

BioResources

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“…De acordo com Pedrazzi et al (2010) são considerados níveis ótimos de refino para polpas de eucalipto destinadas aos segmentos de papéis tisue (750 revoluções PFI) e de imprimir e escrever (35°SR -grau Schopper-Riegler).…”

Section: Propriedades Físico-mecânicas Das Polpas Branqueadasunclassified

Estratégias para maximização do rendimento no processo kraft de polpação para a madeira de eucalipto

Sarto¹

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Strategies for yield maximizing eucalyptus pulping kraft process This work aimed to evaluate changes in the kraft process aiming at the global increase of the bleached eucalyptus pulp production process. For this, the raw material was characterized and then the intensity delignification impact was evaluated, using an industrial unit operating condition with Lo-Solids® digesters, where kappa numbers 17, 23 and 26± 5% were considered. It was also evaluated the inclusion effect of an impregnation vessel for the production 26±5% kappa number pulp where 100 and 120°C temperatures were tested with the 30 and 60 minutes retention time for each temperature tested. Based on the highest yield and the lowest alkali consumption obtained in this step, the optimized condition was determined and than was replicated for kappa number 17 and 23. As high kappa number tends to consume more reagents during the bleaching process and thus a greater environmental impact, the oxygen delignification conditions were changed for each delignification level. Two bleaching sequences were used, after this step the pulps went through the refining process and the physical-mechanical properties were analyzed. The results show that in pulping process using standard condition, the lower delignification intensity the higher yield and consequently the lower specific wood consumption. The impregnation vessel with 30 minutes of retention time and 100°C presented higher yield and lower alkaline consumption, being named in this study as optimized condition. In this condition delignification levels 23 and 26 presented higher yield values, lower specific wood comsumption and lower solids content.The calculated yield after oxygen delignification, which takes into account the pulping process yield and the oxygen delignification yield, present higher yield when the initial pulp kappa nember was higher. In the bleaching sequence DA(Ep)DP, the brightness was similar for the two evaluated pulps, however, brown pulp kappa number 23 presented higher chemical reagents consumption. In the A(PO)DP sequence the 89.5%ISO brightness was not achived under the conditions used. The overall yield in the eucalyptus bleached pulp production showed a gain of 2.39% and a 2.16% in the specific wood consumption 23 kappa number pulp from the impregnation vessel process (otimized condition). In the physical-mechanical tests the brown pulp 23 kappa number presented higher bulk, higher opacity and higher klemm capillarity, while the pulp 17 kappa number presented higher tensile index, burst index and tear index.

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Study of LCNF and CNF from pine and eucalyptus pulps

Demuner

Colodette

Gomes

et al. 2020

Nordic Pulp &Amp; Paper Research Journal

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Nanocelluloses produced from wood pulp are widely studied for various economic applications. Most studies of cellulose nanofibrils (CNF) use lignin-free fibres obtained from bleached pulps; however, unbleached fibres with residual lignin may also be used to obtain lignocelluloses nanofibrils (LCNF). Research on lignocellulose nanofibrils is a recent subject in the field; thus, the aim of the present study was to determine the ultrastructure of lignocellulose nanofibrils compared to cellulose nanofibrils produced from the same raw material. Understanding of nanoparticle properties is of great relevance for their various applications; therefore, complete characterisation of the chemical, physical, and morphological structures of LCNF and CNF produced from pine and eucalyptus woods was performed. Unbleached cellulosic fibres are a viable alternative for LCNF production, which has properties comparable to that of traditional CNF production that uses lignin-free fibres. LCNF from pine and eucalyptus were obtained with 4.0 % and 1.8 % residual lignin, respectively. The nanofibrils had high thermal stability because LCNF had a higher maximum degradation temperature. Due to the low interaction of lignin with water, LCNF had a lower water retention value than CNF.

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Avaliação das propriedades físico-mecânicas de polpas produzidas por novas sequências de branqueamento.

Cited by 7 publications

References 2 publications

Effect of Kappa Number Variation on Modified Pulping of Eucalyptus

Effect of Kappa Number Variation on Modified Pulping of Eucalyptus

Estratégias para maximização do rendimento no processo kraft de polpação para a madeira de eucalipto

Study of LCNF and CNF from pine and eucalyptus pulps

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