Eucalyptus nitens: nanomechanical properties of bark and wood fibers

Muñoz, Freddy; Valenzuela, Paulina; Gacitúa, William

doi:10.1007/s00339-012-7014-3

Cited by 12 publications

(22 citation statements)

References 18 publications

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“…In addition, a higher cell wall fraction increases the modulus of elasticity of the fi ber S2 layer (GINDL et al, 2004;MUÑOZ et al, 2012). The fi bers are the principal constituents of pulp and paper and, therefore, they have to present good mechanical properties (PIRRALHO et al, 2014).…”

Section: Resultsmentioning

confidence: 99%

“…Refining induced fiber collapse, improving their arrangement in the paper sheet by reducing empty spaces and increasing air resistance. Wood fibers from two-yearold trees have a lower cell wall fraction and the poorest mechanical properties, and are therefore more fragile (GINDL et al, 2004;MUÑOZ et al, 2012), resulting in a large amount of fines that fill the voids of the paper and hinder the passage of air (SANTOS; SANSÍGOLO, 2007;PIRRALHO et al, 2014). However, the addition of 5% wood from two-year-old trees resulted in pulp with similar values of air resistance as that for pulp produced with 100% wood from seven-year-old trees.…”

Section: Resultsmentioning

confidence: 99%

“…The gain in the tear index was lower with 3000 revolutions of refining when using 100% wood from two-year-old trees. This is due to the presence of fibers with poorer mechanical properties (MUÑOZ et al, 2012), which broke during the paper production process and explained the reduced tear resistance.…”

Section: Resultsmentioning

confidence: 99%

“…The maximum applied load was 100 µN for 60 seconds, with discharge performed in 20µN/s. The modulus of elasticity was determined according to the equation 3, where: MOE= modulus of elasticity (GPa) according to manufacturer's instructions, vi= 0.07; vm= 0.35, and Ei= 1140 GPA (MUÑOZ et al, 2012). The reduced modulus (Er) was obtained from the load-displacement curve, from the initial unloading slope, wherein, the elastic response was generated (MUÑOZ et al, 2012).…”

Section: Nanoindentationmentioning

confidence: 99%

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PULP PRODUCED WITH WOOD FROM Eucalyptus TREES DAMAGED BY WIND

Zanuncio

Carvalho

Carneiro

et al. 2016

CERNE

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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...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Nanoindentationmentioning

confidence: 99%

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PULP PRODUCED WITH WOOD FROM Eucalyptus TREES DAMAGED BY WIND

Zanuncio

Carvalho

Carneiro

et al. 2016

CERNE

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“…Un método no destructivo para obtener estas propiedades nanomecánicas es la técnica de nanoindentación. Esta técnica ha sido utilizada para investigar el comportamiento de la madera o composite (Wu et al 2009, Muñoz et al 2012, Valenzuela et al 2012a, Konnerth y Gindl 2006, Bustos et al 2011. Otra característica que puede ser considerada para segregar árboles Eucalyptus nitens es la frecuencia de grietas debido a que se presentan de acuerdo a las características del árbol (Valenzuela 2012b, Leandro et al 2008).…”

Section: Introductionunclassified

Caracterización de propiedades mecánicas para segregar familias de Eucalyptus nitens por Nanoindentación en relación al grado de agrietamiento de las trozas

Valenzuela¹,

Bustos²,

J³

et al. 2015

Maderas, Cienc. tecnol.

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RESUMENSeis familias de Eucalyptus nitens provenientes de dos suelos, arcilloso y trumao, localizados en la 8 va Región de Chile, fueron estudiadas para seleccionar aquellas familias con menor grado de agrietamiento. Se relacionaron parámetros de agrietamiento evaluados a mesoescala con las propiedades nanomecánicas en un elemento de volumen representativo de estos árboles. Para segregar las familias se analizó el porcentaje de área de grietas de estos árboles junto a la razón de ductilidad (E/H) obtenidos del módulo de elasticidad (E) y dureza (H) mediante la técnica de nanoindentación y el módulo de resiliencia (u r ) ambos en la lamela media y capa S2 de la pared celular. Además, se determinó la diferencia entre el módulo de resiliencia entre la lamela media y la capa S 2 (Δur), como un indicador de la tensión interfacial que induce fracturas principalmente en la capa S 1 de la estructura celular de la madera. La nanocaracterización permitió establecer que la lamela media es más débil y susceptible a generar microgrietas que se propagan hasta ser visibles formando grietas mayores. El parámetro Δur entre la lamela media y capa S 2 mostró ser menor en las familias 2 y 5. Estas familias presentaron menores niveles de tensión de corte en la interface de la capa S 2 -lamela media, por lo tanto, la cantidad de microgrietas, existiendo una buena relación con el porcentaje de grietas medidos en las familias de Eucalyptus nitens. De acuerdo a esto, las familias segregadas con bajo grado de tensión interfacial a nivel celular y bajo nivel de agrietamiento a mesoescala, fueron las familia 2 y 5. Palabras claves:Eucalyptus nitens, grietas internas, nanoindentaciones, pared celular, propiedades mecánicas. ABSTRACTSix Eucalyptus nitens families from two soils in the 8 th Region of Chile, clay and trumao, were studied to select families with lower degree of cracking. Cracking parameters evaluated at mesoscale, next to nanomechanical properties of the celular structure, were related in a representative volumen element of these tree, such as percentage of cracked area of trees relating them to the ductility ratio (E/H) obtained of values of modulus of elasticity (E) and hardness (H) by nanoindentation and the modulus of resilience (u r ) of the middle lamella and S 2 -layer of the cell wall were analyzed. Furthermore, it was determined that the difference between the modulus of resilience (Δu r ) of the middle lamella with the S 2 -layer is a good indicator of the interfacial stress inducing fractures in the S 1 -layer. Using nanocharacterization it was established that the middle lamella is more brittle and susceptible to generate microcracks that spread to meso scale. The Δu r

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