Effect of compression combined with steam treatment on the porosity, chemical compositon and cellulose crystalline structure of wood cell walls

Yin, Jingbo; Yuan, Tong‐Qi; Lu, Yun; Song, Kunlin; Li, Hanyin; Zhao, Guangbo; Yin, Yafang

doi:10.1016/j.carbpol.2016.08.013

Cited by 92 publications

(42 citation statements)

References 52 publications

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“…After the densification process, group AD (14 pieces) presented lignin content values from 31.6% to 36.8%, and group BD (14 pieces) presented lignin content values from 32.1% to 47.6%. It is known that, after densification, the wood presents changes in its chemical composition (Kutnar and Šernek 2007;Diouf et al 2011;Neyses et al 2016;Yin et al 2017). In this study, it was observed that lignin content increased for both groups (low lignin content and high lignin content).…”

Section: Chemical Composition Of Control and Densified Woodsupporting

confidence: 61%

Impact of the Chemical Composition of Pinus radiata Wood on its Physical and Mechanical Properties Following Thermo-Hygromechanical Densification

Cruz¹,

Bustos²,

Aguayo³

et al. 2018

BioResources

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The thermo-hygromechanical densification process changes the chemical composition and the physical and mechanical properties of wood. The aim of this work was to study the impact of the chemical composition of Pinus radiata wood on its physical and mechanical properties following the thermo-hygromechanical densification process. The samples were initially segregated by lignin content. Density, hardness, modulus of elasticity (MOE), and modulus of rupture (MOR), in addition to lignin, α-cellulose, hemicellulose, and extractive contents, were determined before and after the densification process. The results indicated that densified wood with high initial lignin content had greater rate of increases in density and MOE than wood with lower initial lignin content. Additionally, densified wood with lower initial lignin content had greater rate of increases in hardness. The rate of increase of MOR did not show significant differences within both groups. Carbohydrates present in the control and the densified wood played an important role in the mechanical strength of the final product.

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Section: Chemical Composition Of Control and Densified Woodsupporting

confidence: 61%

Impact of the Chemical Composition of Pinus radiata Wood on its Physical and Mechanical Properties Following Thermo-Hygromechanical Densification

Cruz¹,

Bustos²,

Aguayo³

et al. 2018

BioResources

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“…Treatments such as delignification or fungal degradation can enlarge micropores, thus allowing their direct observation. Most of the studies on cell wall mesopores have been performed using such altered samples (Davies, 1968;Donaldson, 1988;Blanchette et al, 1997;Hill and Papadopoulos, 2001;Xu et al, 2007;Kojiro et al, 2010;Borrega and Kärenlampi, 2011;Ciesielski et al, 2013;Pu et al, 2013;Yin et al, 2017). It is possible to measure the size distribution of all pores by physicochemical methods, such as porosimetry, gas adsorption, or freezing point depression; however, these methods provide only a bulk measurement of pore size range, including that for both micropores and mesopores (Hill and Papadopoulos, 2001;Grigsby et al, 2013).…”

Section: CMmentioning

confidence: 99%

Comparison of Micropore Distribution in Cell Walls of Softwood and Hardwood Xylem

2018

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The porosity of wood cell walls is of interest for both understanding xylem functionality and from a wood materials perspective. The movement of water in xylem generally occurs through the macroporous networks formed in softwood by bordered pits and in hardwood by the intervessel pits and open conduits created by vessels and perforation plates. In some situations, such as cavitated xylem, water can only move through the micropores that occur in lignified tracheid and fiber cell walls; however, these micropore networks are poorly understood. Here, we used molecular microscopy analysis of radiata pine () and red beech () to determine the distribution of micropores in the secondary walls and middle lamellae of tracheids and fibers in relation to cell wall composition. Using two different types of probe, we identified a greater porosity of secondary cell walls and a reduced porosity of the middle lamella. Areas of reduced porosity were observed in the outer regions of the secondary cell wall of both tracheids and fibers that appear unrelated to lignification or the distribution of cellulose, mannan, and xylan. Hardwood fiber cell walls were less lignified than those of softwood tracheids and showed greater accessibility to porosity probes. Vessel cell walls were comparable to those of fibers in terms of both porosity and lignification. Lignification is probably the primary determinant of cell wall porosity in xylem. The highly lignified middle lamella, and lumen surface, act as a barrier to probe movement and, therefore, water movement in both softwood and hardwood.

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“…The process of softening is known as a pretreatment and combined with following mechanical pressing, achieving better compressing result. The thermo-mechanical densification [3][4][5], thermal-hydromechanical [6][7][8], hygro-mechanical steam treatment [9,10], mechanical-microwave treatment [11], and highpressure treatment [12,13] were developed to manufacture densified wood, in which the thermal-hydro is the most common and simplest pretreatment method currently. The cell walls of wood would be swelled by water although it cannot penetrate into crystalline region of cellulose.…”

Section: Introductionmentioning

confidence: 99%

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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Effect of compression combined with steam treatment on the porosity, chemical compositon and cellulose crystalline structure of wood cell walls

Cited by 92 publications

References 52 publications

Impact of the Chemical Composition of Pinus radiata Wood on its Physical and Mechanical Properties Following Thermo-Hygromechanical Densification

Impact of the Chemical Composition of Pinus radiata Wood on its Physical and Mechanical Properties Following Thermo-Hygromechanical Densification

Comparison of Micropore Distribution in Cell Walls of Softwood and Hardwood Xylem

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

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