The Influence of Process Parameters on the Density Profile and Hardness of Surface-densified Birch Wood (Betula pendula Roth)

Laskowska, Agnieszka

doi:10.15376/biores.12.3.6011-6023

Cited by 26 publications

(17 citation statements)

References 19 publications

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“…As well known, many studies investigated various compression Table 1 The band intensity and ratio of pristine wood (PW) and densified wood (DW) a and b values indicate the intensity ratio of the absorption band and the maximum absorption band near 1027 cm −1 in that curve ratios of densified wood under different processing conditions. It was reported that the compression ratio was generally lower than 30% after the densification without any chemical pretreatment [33,34]. However, in this work, the average compression ratio was approximately 80% in the radial direction of wood.…”

Section: Ftir Analysismentioning

confidence: 49%

Fabrication of densified wood via synergy of chemical pretreatment, hot-pressing and post mechanical fixation

Shi

Peng

Huang³

et al. 2020

J Wood Sci

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Wood densification can improve the strength of low density wood species and extend wood product applications. To enhance the wood compressive quality, chemical pretreatments for pristine wood have widely been used. Densified Abies wood was fabricated by combining NaOH/Na 2 SO 3 solution treatment, hot-pressing and post mechanical fixation. The appearance, color, chemical composition, and physiology and mechanical properties before and after the densification treatment were examined by the colorimeter, FTIR and mechanical testing machine, respectively. Surface color of Abies wood was changed obviously after the densification. The values of brightness L* and b* decreased but the value of a* showed a slight increase in the densified wood. FTIR results confirmed that the color changes can be explained by the degradation of hemicellulose and lignin in wood cell walls and migration of extractives during the densification process. Sufficient removal of wood polymers resulted in the average compression ratio of about 80% in the radial direction of the natural wood. The density of densified wood increased with the wood thickness up to 1.227 g cm −1 , accounting for a 169% increase compared to that of the pristine wood. Modulus of rupture (MOR) and modulus of elasticity (MOE) in the thickness direction of densified wood also markedly enhanced. Degradation of polymers in wood cell walls also was reconfirmed by the difference of fracture interface. All the results suggested that the densified softwood can be easily fabricated using the proposed method and the new densified softwood can be appropriately used as interior decoration materials.

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Section: Ftir Analysismentioning

confidence: 49%

Fabrication of densified wood via synergy of chemical pretreatment, hot-pressing and post mechanical fixation

Shi

Peng

Huang³

et al. 2020

J Wood Sci

View full text Add to dashboard Cite

show abstract

“…Among these processes, densification is obtained by compressing wood in transverse direction causing cell lumina to obliterate and wood density to increase [3]. The increased wood density should then translate into increased wood mechanical performances [4][5][6][7][8][9]. Densification by compression can be preceded by heating wood at high temperatures [10], or softening it with hot steam [2,11,12] or by chemical treatments or impregnation with resins [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Effects of an innovative densification process on mechanical and physical properties of beech and Norway spruce veneers

et al. 2021

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Increased wood density is obtained by compressing the wood porous structure under suitable moisture and temperature conditions to improve its physical, mechanical and color properties. A recently proposed wood densification method based on partial removal of lignin and hemicellulose in hot water solution of sodium hydroxide and sodium sulphite has shown promising results on solid wood. However, its applicability and effect on thin wood veneers have not been tested yet. In this study, the timing of the method has been adapted to estimate the densification treatment intensity dependence of wood properties (wood density and modulus of elasticity) and color change of softwood (Norway spruce) and hardwood (beech) veneers. Compared to control, density and rigidity increased, with improved wood properties peaking after only 90 s of treatment intensity. Furthermore, the color became darker after treatment compared to control, with no significant color difference between treatment intensities. In conclusion, densification of veneers, according to the presented adapted method, provides a significant improvement of veneers physical and mechanical properties, and produces color changes perceptible by the human eye. Our results can be further implemented and adapted to application in industrial plants, calling for new application of densified veneers.

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“…Wood densification improves the physical and mechanical properties of solid wood by increasing the wood density via reducing the void volume of the lumens [1][2][3]. Most studies on wood densification refer to wood surface densification, which is generally achieved by surface pressing at high temperatures (higher than 140 °C) after long terms of conditioning for uniform moisture distribution or after water spraying on surfaces [4][5][6][7][8][9]. However, the position and thickness of the compressed layer(s) are not controllable.…”

Section: Introductionmentioning

confidence: 99%

Effects of preheating temperature, preheating time and their interaction on the sandwich structure formation and density profile of sandwich compressed wood

Qin

Huang

et al. 2019

J Wood Sci

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Effects of preheating times (4, 8, and 12 min), preheating temperatures (75-210 °C, with 15 °C interval), and their interactions on structures and density profiles of sandwich compressed poplar wood (Populus × euramericana cv. 'Neva') were studied to achieve better control of the position(s) of compressed layer(s), with the aim of better utilization of the low-density wood resources. Our findings revealed that, as a result of preheating temperature elevation or preheating time extension, compressed layers move gradually from wood surfaces to wood interior center, forming three types of sandwich compressed wood, namely, surface compressed wood, internal compressed wood, and central compressed wood. The characteristics of wood cell deformation in the sandwich compressed wood match well with the density distribution, and no obvious cell-wall cracks were observed. Effects of preheating temperature, preheating time, and preheating temperature-time interaction on the density of the compressed layer(s) are statistically insignificant. But their effects on the position and thickness of the compressed layer(s) in the sandwich compressed wood were statistically highly significant (p < 0.001), and the preheating temperature and compressed layer(s) positions were significantly related to the functions and fitted the polynomial of the fourth order. which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

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The Influence of Process Parameters on the Density Profile and Hardness of Surface-densified Birch Wood (Betula pendula Roth)

Cited by 26 publications

References 19 publications

Fabrication of densified wood via synergy of chemical pretreatment, hot-pressing and post mechanical fixation

Fabrication of densified wood via synergy of chemical pretreatment, hot-pressing and post mechanical fixation

Effects of an innovative densification process on mechanical and physical properties of beech and Norway spruce veneers

Effects of preheating temperature, preheating time and their interaction on the sandwich structure formation and density profile of sandwich compressed wood

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