Changes in the properties of wood cell walls during the transformation from sapwood to heartwood

Song, Kunlin; Yin, Yafang; Salmén, Lennart; Xiao, Fangming; Jiang, Xiaomei

doi:10.1007/s10853-013-7860-1

Cited by 54 publications

(39 citation statements)

References 41 publications

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“…Due to possible variations in the specimens size, the E′′ data represent approximate values but this is not relevant because only relative trends are compared. In Figure 2, the effects of frequency are presented for the storage modulus, E′ and tanδ; both data are positively correlated with the frequency, in agreement with previous studies of different wood samples (Wennerblom et al 1996;Song et al 2014).…”

Section: Resultssupporting

confidence: 88%

“…In addition, noncovalent interactions (mainly hydrogen bonding interactions) among the wood components are much weaker than that between water and the wood cell wall. Under soaked condition, the T g is between 50°C and 100°C, depending on the native lignin structure and the frequency of the measurement (Sadoh 1981;Hagen and Salmén 1994;Song et al 2014;Zhan et al 2016). A clear relation between lignin structure and wood softening has not yet been established.…”

Section: Introductionmentioning

confidence: 99%

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Effects of thermo-hygro-mechanical (THM) treatment on the viscoelasticity of in-situ lignin

et al. 2017

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For producing wood products without fractures based on thermo-hygro-mechanical (THM) treatments, it is essential to understand how steaming and compression change the wood softening and cell wall components. In this paper, the effects of compression combined with steam treatment (CS) on the viscoelasticity of the in-situ lignin of Chinese fir has been investigated through dynamic mechanical analysis (DMA) under fully saturated conditions. Several variations were studied, such as the softening temperature (T g ) and apparent activation energy (ΔH a ) of the softening process in response to CS treatment conditions (such as steam temperature and compression ratio) under separate consideration of earlywood (EW) and latewood (LW). No difference between EW and LW with respect to the viscoelasticity was noted. T g and ΔH a of the lignin softening were nearly unaffected by the compression ratio, but were highly influenced by the steam temperature. The T g decreased significantly with CS treatments at or above 160 o C, but showed no appreciable change, compared to the native wood, at the lower steaming temperature of 140 o C. ΔH a increased at higher steam temperatures, while ΔH a showed a decreasing tendency with decreasing T g . This indicates that lignin undergoes a simultaneous depolymerization as well as a condensation during CS treatment.

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Section: Resultssupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Effects of thermo-hygro-mechanical (THM) treatment on the viscoelasticity of in-situ lignin

et al. 2017

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“…Wood cell walls are generally to be regarded as natural fibre biocomposites made up of stiff cellulose, a soft polymer matrix (hemicelluloses and lignin) with extractives and pectins accumulated during the cell growth (Kuo and Arganbright 1980;Sundberg et al 1996). There are no obvious differences in the main components during the heartwood formation (Song et al 2014). However, extractives are accumulated in the cell walls during the heartwood formation.…”

Section: \00044mentioning

confidence: 94%

Comparison of changes in micropores and mesopores in the wood cell walls of sapwood and heartwood

Yin

Song

et al. 2015

Wood Sci Technol

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The objective of this paper was to investigate size distribution of micropores and mesopores within the wood cell walls between sapwood and heartwood by using nitrogen adsorption method and to find out implications for the biological durability and further processing such as in drying and preservation treatment. The pore shape, specific surface area and pore size distribution of Chinese fir (Cunninghamia lanceolata) were evaluated using the hysteresis loops, Brunauer-Emmett-Teller (BET) and density functional theories, respectively. Both the sapwood and heartwood exhibited slit-shaped pores with regard to the H3 type of hysteresis loop of the isotherm. However, more mesopores were found in the sapwood, while the micropores increased with a decrease in mesopores in the heartwood. Furthermore, the earlywood and latewood in the sapwood had a higher BET-specific surface area (2.088 and 1.255 m 2 g -1 , respectively) compared with the earlywood (1.058 m 2 g -1 ) and latewood (0.787 m 2 g -1 ) in the heartwood. This could be caused by an increase in depositions in the extractive that partly filled the mesopores of the heartwood cell walls during the transformation from the sapwood. Additionally, a larger amount of mesopores existed in the earlywood in comparison with the latewood in the sapwood. However, there was no significant difference in the amounts of the micropores and mesopores, when comparing the earlywood with the latewood in the heartwood.

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“…As automated sorption balances are becoming a common research tool in wood research laboratories, the literature is abundant with sorption isotherms determined with such equipment, also for various types of modified wood Jalaludin et al 2010a, b;Popescu and Hill 2013;Xie et al 2010Xie et al , 2011. While the low sample mass makes possible detailed studies of differences in water sorption between earlywood and latewood (Fredriksson and Thygesen 2017), even at the growth ring level (Hill et al 2015;Song et al 2014), it also requires the user to consider how to collect representative samples for the study in question. For generating representative samples of larger wood volumes, several studies have used milled wood Himmel and Mai 2015;Xie et al 2010;Zaihan et al 2009Zaihan et al , 2011, but it could be speculated if this gives a representative material or might produce unwanted side effects, for example a change in sample chemistry.…”

Section: Automated Sorption Balancesmentioning

confidence: 99%

“…lignin-rich middle lamella fragments) are over-represented in smaller size fractions that are more easily lost upon handling the milled material. Instead of milling, several studies have used wood slices cut with a microtome or razor blade to produce a large sample surface area while preserving the microscopic wood structure (Fredriksson and Thygesen 2017;Fredriksson et al 2010;Glass et al 2017;Hill et al 2015;Hosseinpourpia et al 2016;Song et al 2014), while a few use small wood blocks (Fredriksson and Johansson 2016). All of these studies use the automated humidity control by which RH is automatically changed upon reaching a specified mass stability (dm/dt) criterion.…”

Section: Automated Sorption Balancesmentioning

confidence: 99%

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

2017

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Water plays a central role in wood research, since it affects all material properties relevant to the performance of wood materials. Therefore, experimental techniques for characterising water within wood are an essential part of nearly all scientific investigations of wood materials. This review focuses on selected experimental techniques that can give deeper insights into various aspects of water in wood in the entire moisture domain from dry to fully water-saturated. These techniques fall into three broad categories: (1) gravimetric techniques that determine how much water is absorbed, (2) fibre saturation techniques that determine the amount of water within cell walls, and (3) spectroscopic techniques that provide insights into chemical wood-water interactions as well as yield information on water distribution in the macro-void wood structure. For all techniques, the general measurement concept is explained, its history in wood science as well as advantages and limitations.

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Changes in the properties of wood cell walls during the transformation from sapwood to heartwood

Cited by 54 publications

References 41 publications

Effects of thermo-hygro-mechanical (THM) treatment on the viscoelasticity of in-situ lignin

Effects of thermo-hygro-mechanical (THM) treatment on the viscoelasticity of in-situ lignin

Comparison of changes in micropores and mesopores in the wood cell walls of sapwood and heartwood

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

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