An Optimal Thermo-Hydro-Mechanical Densification (THM) Process for Densifying Balsam Fir Wood

Li, Ling; Gong, Meng; Yuan, Naxin; Li, Dagang

doi:10.15376/biores.8.3.3967-3981

Cited by 12 publications

(11 citation statements)

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“…3a and 3c, hardness decreased with increasing temperature. This result is in agreement with the results reported by Fang et al (2012a) and Li et al (2013). The reason for the decrease in hardness as temperature increased could be explained by the advanced degradation of lignin and hemicelluloses (Fang et al 2012b).…”

Section: Effect Of Process Factors On Hardness and Reliability Of Thesupporting

confidence: 92%

“…Thermohygromechanical (THM) compression treatment is a modified method that utilizes steam, heat, and pressure to densify wood. THM compression effectively eliminates the shape memory effect in compressed wood while improving its physical, mechanical, and dimensional stability (Navi and Girardet 2000;Heger et al 2004;Fang et al 2012a;Li et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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Optimization of the Thermo-Hygromechanical (THM) Process for Sugar Maple Wood Densification

Fu¹,

Cloutier²,

Laghdir³

2016

BioResources

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Densified wood is a promising engineered wood product, especially for heavy-duty applications. This study optimized the temperature and duration of the thermo-hygromechanical (THM) densification process applied to sugar maple (Acer saccharum Marsh.) wood. The response variables studied were compression set recovery and hardness. The THM densification process was performed at three temperatures (180°C, 200 °C, and 220 °C), densification times (450 s, 900 s, and 1350 s), and posttreatment times (900 s, 1350 s, and 1800 s). Response surface methodology was used to analyze the impact of the three parameters. The effect of temperature on the density profile across thickness was also determined. The results suggested that the optimum densification conditions resulting in high hardness and low compression set recovery were obtained at a temperature of 180 °C, a densification time of 1004 s, and a post-treatment time of 1445 s. Additionally, the density of the densified samples was relatively homogeneous across thickness, although it was dramatically increased compared with control samples. However, density did not increase linearly with temperature. A much higher weight loss occurred at 220 °C, resulting in a significant decrease in density and hardness, whereas little compression set recovery was observed for sugar maple densified at this temperature.

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Section: Effect Of Process Factors On Hardness and Reliability Of Thesupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Optimization of the Thermo-Hygromechanical (THM) Process for Sugar Maple Wood Densification

Fu¹,

Cloutier²,

Laghdir³

2016

BioResources

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“…Increasing the density of bamboo elements can lead to more efficient use of structural products because the quality of the final product depends on the performance of its components. Wood densification has been investigated and comprehensively reported [ 10 , 11 , 12 , 13 , 14 ]. Kutnar et al 2015 summarized the state of the art and knowledge in the field of compressed wood processing and products [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

Densification of Bamboo: State of the Art

et al. 2020

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Densification processes are used to improve the mechanical and physical properties of lignocellulose materials by either collapsing the cell cavities or by filling up the pores, consequently reducing the void volume fraction. This paper focuses on an extensive review of bamboo densification process, which is achieved by compressing the material in the direction perpendicular to the fibers using mainly two different techniques: an open system, thermo-mechanical (TM), or a closed system, viscoelastic-thermal-compression (VTC). The main aim of bamboo densification is to decrease its heterogeneity, as well as to improve its mechanical and physical performance. In addition, densification may occur during the manufacturing of bamboo products in which hot-pressing processes are used to mold bamboo panels. There are over 1600 publications about bamboo, concentrated in the recent decade, mainly about engineered materials. Although several papers regarding bamboo and wood densification are available, very few studies have comprehensively investigated the densification process solely through compression of natural bamboo culms. According to the literature, applying a combination of compression of 6–12 MPa at temperatures between 120–170 °C for 8–20 min can produce materials with higher strength in comparison to the mechanical properties of natural bamboo. The majority of research on bamboo densification indicates that the modified material results in improved properties in terms of density, hardness, bending strength, stiffness, and durability. This paper provides a review that consolidates knowledge on the concept of bamboo culm densification, discusses the roles of parameters that control the process, ascertains the best practice, and finally determines gaps in this field of knowledge.

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“…The main purpose of densification is to enhance wood density, which improves its mechanical performance and commercial value. In recent years, many research efforts have been dedicated to using the appropriate densification process to improve wood properties [2,3,4,5,6,7,8,9,10]. Koumba et al [11] reported that the wood densification process acts as a mild thermo-chemical pre-treatment which can impact biomass composition and structure.…”

Section: Introductionmentioning

confidence: 99%

Surface Chemical Changes of Sugar Maple Wood Induced by Thermo-Hygromechanical (THM) Treatment

Cloutier

Laghdir

et al. 2019

Materials

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The aim of this study was to investigate the effects of heat and steam on the chemical properties of thermo-hygromechanical (THM)-densified sugar maple wood. The THM densification process was performed at two different temperatures (180 °C and 200 °C) with and without steam. The functional groups, surface chemical composition and internal structure and components of the control and densified samples were investigated using attenuated total reflection Fourier transform infrared (ATR-FTIR), X-ray photoelectron (XPS) spectroscopy and pyrolysis gas chromatography-mass spectrometry (Py-GC/MS). The obtained results suggest that the THM densification treatment resulted in significant chemical changes on the wood surface. The results of the ATR-FTIR spectra confirmed the decomposition of hemicelluloses and the relative increase of cellulose and lignin contents on the wood surface. The Py-GC/MS and XPS results show an increase of the oxygen/carbon atomic (O/C) ratio, which indicated that chemical substances containing oxygenated functionality were formed through the densification process. The densification treatment favored the depolymerization of hemicelluloses and cellulose as indicated by an increased anhydrous sugar (levoglucosan) release during the pyrolysis process. Densification also facilitated the cleavage of the lignin side chains, resulting in increased phenyl units with short chains released during the pyrolysis process.

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An Optimal Thermo-Hydro-Mechanical Densification (THM) Process for Densifying Balsam Fir Wood

Cited by 12 publications

References 0 publications

Optimization of the Thermo-Hygromechanical (THM) Process for Sugar Maple Wood Densification

Optimization of the Thermo-Hygromechanical (THM) Process for Sugar Maple Wood Densification

Densification of Bamboo: State of the Art

Surface Chemical Changes of Sugar Maple Wood Induced by Thermo-Hygromechanical (THM) Treatment

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