Mechanical behavior of chemically modified Norway spruce: a generic hierarchical model for wood modifications

Méndez, Diego Fernando Mora; Olaniran, Samuel Oluyinka; Rüggeberg, Markus; Burgert, Ingo; Herrmann, Hans J.; Wittel, Falk K.

doi:10.1007/s00226-019-01082-3

Cited by 10 publications

(14 citation statements)

References 33 publications

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“…The influence of the material density ρ on the Poisson's ratios νLT (Figure 14(a), tangential plane), and νRT (Figure 14(c), transverse plane) is mild, and on the Poisson's ratio νLR (Figure 14(b), radial plane) is negligible. Further, in correspondence with the experimental results presented in [61], the Poisson's ratios only slightly increase under an increasing moisture content, with the exception being the somewhat more substantial increase for νLT in case the S2 layer of axial cells is characterized by the larger micro-fibre angle of 20 • , see the red curves in Figure 14(a). The effect on the Poisson's ratio by a change in MFA from 10 • to 20 • is the largest for νLT , followed by νLR and νRT .…”

Section: Effective Elastic Properties Of Oaksupporting

confidence: 89%

A 3D multi-scale hygro-mechanical model of oak wood

Livani

Suiker

Crivellaro

et al. 2023

Preprint

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A multi-scale framework is proposed for the prediction of the macroscopic hygro-elastic properties of oak wood. The distinctive features of the current multi-scale approach are that: i) four different scales of observation are considered, which enables the inclusion of heterogeneous effects from the nano-, micro-, and meso-scales in the effective constitutive behaviour of oak at the macro-scale, ii) the model relies on three-dimensional material descriptions at each considered length scale, and iii) a moisture-dependent constitutive assumption is adopted at the nano-scale, which allows for recovering the moisture dependency of the material response at higher scales of observation. In the modelling approach, oak wood is considered homogeneous at the macro-scale. The meso-scale description considers the cellular structure of individual growth rings with three different densities. At the micro-scale, the heterogeneous nature of cell walls is described by the characteristics of the primary and secondary cell wall layers. Finally, the nano-scale response is determined by cellulose micro-fibrils embedded in a matrix of hemicellulose and lignin. The oak properties at the four length scales are connected via a three-level homogenization procedure, whereby, depending on the geometry of the fine-scale configuration, an asymptotic homogenization procedure or Voigt averaging procedure is applied at each level to determine the effective hygro-elastic properties at the coarse scale. In addition, the moisture ad-sorption isotherms at each scale are constructed from a volume-weighted averaging of the moisture adsorption characteristics at the scale below. The computational results demonstrate that the moisture-dependent, hygro-elastic behaviour of oak wood is predicted realistically at each considered length scale, thereby revealing the influence of the material density, the micro-fibril orientation, and the hygro-elastic properties at the underlying scales. The computed macro-scale properties of oak are in good agreement with experimental data reported in the literature.

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Section: Effective Elastic Properties Of Oaksupporting

confidence: 89%

A 3D multi-scale hygro-mechanical model of oak wood

Livani

Suiker

Crivellaro

et al. 2023

Preprint

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“…Micromechanical models for wood can capture the hygromechanical behavior of representative samples, by considering the material properties at smaller length scales. [ 78,79 ] With today's computational power, finite element method (FEM) calculations on large RVE, which capture the tissue morphology with thousands of tracheids/fibers at reasonable times and costs, are feasible to determine the hygromechanical constitutive parameters. This numerical homogenization can provide the macroscopic engineering constants (e.g.…”

Section: Assessing Cellulose Scaffold Mechanicsmentioning

confidence: 99%

“…Hierarchical model comprising S2, cell wall, and growth ring level to describe the hygromechanical behavior of wood with chemical modifications. [ 79,80 ] Adapted with permission. [ 79 ] Copyright 2019, Springer Nature.…”

Section: Assessing Cellulose Scaffold Mechanicsmentioning

confidence: 99%

“…Here, one can use direct information on the tissue morphology from individual microsections or statistical data on lumen and cell wall geometry collected from large datasets and employ an artificial tissue generation algorithm that generates tissue sections with characteristics sampled from the statistical data. [ 79 ] With FEM, RVEs for entire growth rings are feasible, and by using different boundary conditions, it is possible to calculate all properties of the orthotropic macroscopic stiffness tensor. If treatments like delignification processes alter the components interactions, modifications at the respective scales are necessary, while the hierarchical scheme remains.…”

Section: Assessing Cellulose Scaffold Mechanicsmentioning

confidence: 99%

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Wood Derived Cellulose Scaffolds—Processing and Mechanics

et al. 2020

Self Cite

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Wood‐derived cellulose materials obtained by structure‐retaining delignification are attracting increasing attention due to their excellent mechanical properties and great potential to serve as renewable and CO2 storing cellulose scaffolds for advanced hybrid materials with embedded functionality. Various delignification protocols and a multitude of further processing steps including polymer impregnation and densification are applied resulting in a large range of properties. However, treatment optimization requires a more comprehensive characterization of the developed materials in terms of structure, chemical composition, and mechanical properties for faster progress in the field. Herein, the current protocols for structure‐retaining delignification are reviewed and the emphasis is placed on the mechanical characterization at different hierarchical levels of the cellulose scaffolds by experiments and modeling to reveal the underlying structure–property relationships.

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“…Chinese fir is a typical coniferous wood due to its lightweight and ease of processing, but its yellowish-white color is monotonous and unable to meet the diverse needs of modern consumers. Research on spruce has primarily focused on thermal modification, material composites, pulping, and physical mechanics testing, − with limited research on pretreatment methods. White oak is a heavy and hard broad-leaf material with good machinability and strong compression and bending resistance.…”

Section: Introductionmentioning

confidence: 99%

Effect of NaOH Pretreatment on Permeability and Surface Properties of Three Wood Species

Qi,

Zhou,

et al. 2023

ACS Omega

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To improve the permeability of wood, three chemical reagents were used to pretreat Chinese fir, white oak, and poplar. Through a factorial experiment with the mass change rate of the wood as the indicator, NaOH was preliminarily selected as the pretreatment agent. Further orthogonal experiments were conducted to explore the effects of NaOH concentration, temperature, and treatment time on the mass change rate, dye uptake rate, transverse dye penetration rate, and color difference of the wood. A fuzzy, comprehensive analysis was used to optimize the pretreatment process. The results showed that after NaOH pretreatment, the highest mass change rates of Chinese fir, white oak, and poplar were 11.30, 10.66, and 8.53%, respectively. Compared with untreated wood, the dye uptake rate of three wood species increased by 1.05, 1.43, and 1.13 times, respectively; the radial dye penetration rate increased by 5.05, 4.14, and 3.38 times, respectively; and the tangential dye penetration rate increased by 3.91, 3.45, and 3.84 times, respectively. These findings indicate an enhancement in permeability for all three wood species following NaOH pretreatment. The brightness of the three wood species decreased after NaOH pretreatment, while the yellow and red colors increased in Chinese fir and poplar and decreased in white oak. Scanning electron microscopy showed that pits in the wood opened after pretreatment, while extractives decreased. Infrared spectroscopy analysis indicated varying degrees of extraction effects from NaOH pretreatment across the three wood species, along with increased active hydroxyl groups within the wood structure. X-ray diffraction analysis revealed that NaOH dissolved noncrystalline substances in wood, leading to improved crystallinity. These experimental findings provide essential data for future endeavors in wood pretreatment and subsequent staining processes.

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Mechanical behavior of chemically modified Norway spruce: a generic hierarchical model for wood modifications

Cited by 10 publications

References 33 publications

A 3D multi-scale hygro-mechanical model of oak wood

A 3D multi-scale hygro-mechanical model of oak wood

Wood Derived Cellulose Scaffolds—Processing and Mechanics

Effect of NaOH Pretreatment on Permeability and Surface Properties of Three Wood Species

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