Dynamic and static mechanical properties of Eucalyptus nitens thermally modified in an open and closed reactor system

Wentzel, Maximilian; Brischke, Christian; Militz, Holger

doi:10.4067/s0718-221x2019005000201

Cited by 10 publications

(13 citation statements)

References 31 publications

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“…The catastrophic and brittle failure of the cell wall in dry heat-treated veneers, which was shown by SEM, indicated a rupture of the cellulose chains rather than a failure via interface debonding and pull-out of the fibrils. Dry-HT may have promoted the scission of the cellulose chains, which has been shown previously by the decrease in the degree of polymerization (DP) of cellulose despite an increase in cellulose content [45,46]. A decrease in cellulose DP also occurs during hot water extraction [47,48].…”

Section: Discussionmentioning

confidence: 65%

Micro-tensile behavior of Scots pine sapwood after heat treatments in superheated steam or pressurized hot water

et al. 2020

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Heat treatments reduce the strength and ductility of wood, but the extent depends on the direction of load and the treatment conditions applied. The tensile behavior of wood is very sensitive to heat treatments, but there is a lack of understanding how this is related to different heat treatment conditions. In this study, we treated homogeneous micro-veneers under different time-, temperature-, and moisture-environments and compared the effect on the tensile behavior of the treated veneers based on their chemical composition changes. The results confirmed the adverse effect of the preferential hemicellulose removal on the strength and toughness of wood. However, chemical composition changes could not fully explain the tensile behavior of dry heat-treated wood, which showed an additional loss in maximum load and work in traction at the same residual hemicellulose content compared to wet heat-treated wood. The scission of cellulose chains as well as the enhanced cross-linking of the cell wall matrix under dry heat conditions and elevated temperatures was discussed as additional factors. The enhanced cross-linking of the cell wall matrix helped in preserving the tensile properties when testing the veneers in water-saturated state, but may have also promoted the formation of cracks that propagated across the cell wall during tensile loading.

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Section: Discussionmentioning

confidence: 65%

Micro-tensile behavior of Scots pine sapwood after heat treatments in superheated steam or pressurized hot water

et al. 2020

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“…1,5 Contrarily, another study asserted that different modification system (open and closed system) does not have a significant bearing on anatomical changes. 13 Scanning electron microscopy observation SEM analyses of untreated and tin-bath treated F. simplex wood are shown in Figures 5-7. The microstructure observation of the untreated samples revealed that the vessels and the cell walls of the wood were intact as well as the visibility of other wood structures ( Figure 5).…”

Section: Transmission Light Microscope Observationmentioning

confidence: 99%

Effect of tin-bath treatment on anatomical properties of Firmiana simplex wood

Okon¹,

Akpan²,

Okon³

et al. 2020

MOJES

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Wood modification in general, is an environmental non-biocide method to modify and improve certain wood properties to enable its utilization for diverse purpose. In this study, Firmiana simplex wood was modify using low melting point tin-alloy as the heat-treatment medium. The anatomical properties of the tin-bath treated wood were studied using a light microscope and scanning electron microscope analysis. Microscopic analyses with a light microscope showed that the morphologies of the wood were less smashed by the impact of the treatment with no deformation of the vessels after tin-alloy treatment while scanning electron microscope revealed collapse in the wood structures with damages to the cell walls and vessels. It was also evident from scanning electron microscope analyses that tin-alloy penetrated the wood structure, therefore forming a film covering the cell walls and partly occupying the wood cell lumens.

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“…Seeking to improve the mechanical properties of this type of timber, Wentzel et al [ 13 , 14 ] studied the feasibility of increasing the physical-mechanical properties of Eucalyptus nitens boards through thermal modification, looking for its application in outdoor exposed decking. Another novel research line has been to the production on structural panels made of Eucalyptus nitens .…”

Section: Introductionmentioning

confidence: 99%

Non-Destructive Assessment of the Dynamic Elasticity Modulus of Eucalyptus nitens Timber Boards

2021

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Eucalyptus nitens is a fast-growing wood species with a relevant presence in countries like Australia and Chile. The sustainable construction goals have driven the search of structural applications for Eucalyptus nitens; however, this process has been complicated due to the defects usually presented in these timber boards. This study aims to evaluate the dynamic elasticity modulus (Exd) of Eucalyptus nitens timber boards through non-destructive vibration-based tests. Thirty-six timber boards with different levels of knots and cracks were instrumented and tested in a simply supported condition by measuring longitudinal and transverse vibrations. In the first stage, the Exd was calculated globally through simplified normative formulas. Then, in a second stage, the local variability of the Exd was estimated using operational modal analysis (OMA), finite element numerical simulations (FEM), and regional sensitivity analysis (RSA). The positive correlation found between the global static modulus of elasticity and Exd suggests that non-destructive techniques could be used as a reliable and fast alternative for the assessment of bending stiffness. Finally, the proposed method to estimate the local variability of Exdt based on the combination of OMA, FEM, and RSA techniques was useful to improve the structural selection process of timber boards for lightweight social housing floors.

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Dynamic and static mechanical properties of Eucalyptus nitens thermally modified in an open and closed reactor system

Cited by 10 publications

References 31 publications

Micro-tensile behavior of Scots pine sapwood after heat treatments in superheated steam or pressurized hot water

Micro-tensile behavior of Scots pine sapwood after heat treatments in superheated steam or pressurized hot water

Effect of tin-bath treatment on anatomical properties of Firmiana simplex wood

Non-Destructive Assessment of the Dynamic Elasticity Modulus of Eucalyptus nitens Timber Boards

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