Dried cell wall nanopore configuration of Douglas-fir, western red cedar and aspen heartwoods

Shi, Jingbo; Avramidis, Stavros

doi:10.1007/s00226-018-1011-4

Cited by 21 publications

(8 citation statements)

References 36 publications

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“…Pore size distribution using the Barrett–Joyner–Halenda model is based on cylindrical pores and often used in analysis of wood pulp fiber pore structures. [ 32 ] For the ultra‐structures of wood cell walls in this work, a model based on non‐local density functional theory with density‐independent weights and a slit‐like pore geometry [ 33 ] was used to analyze the pore size distribution using nitrogen adsorption data. The results are plotted in Figure 2b and both TEMPO‐oxidized wood and delignified wood show a mesoporous structure.…”

Section: Figurementioning

confidence: 99%

Self‐Densification of Highly Mesoporous Wood Structure into a Strong and Transparent Film

et al. 2020

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In the native wood cell wall, cellulose microfibrils are highly aligned and organized in the secondary cell wall. A new preparation strategy is developed to achieve individualization of cellulose microfibrils within the wood cell wall structure without introducing mechanical disintegration. The resulting mesoporous wood structure has a high specific surface area of 197 m2 g−1 when prepared by freeze‐drying using liquid nitrogen, and 249 m2 g−1 by supercritical drying. These values are 5 to 7 times higher than conventional delignified wood (36 m2 g−1) dried by supercritical drying. Such highly mesoporous structure with individualized cellulose microfibrils maintaining their natural alignment and organization can be processed into aerogels with high porosity and high compressive strength. In addition, a strong film with a tensile strength of 449.1 ± 21.8 MPa and a Young's modulus of 51.1 ± 5.2 GPa along the fiber direction is obtained simply by air drying owing to the self‐densification of cellulose microfibrils driven by the elastocapillary forces upon water evaporation. The self‐densified film also shows high optical transmittance (80%) and high optical haze (70%) with interesting biaxial light scattering behavior owing to the natural alignment of cellulose microfibrils.

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Section: Figurementioning

confidence: 99%

Self‐Densification of Highly Mesoporous Wood Structure into a Strong and Transparent Film

et al. 2020

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“…Based on the high standard deviation, nitrogen as adsorptive appears to be unsuitable for physisorption analysis of wood. This contradicts hitherto published research where nitrogen physisorption was used to differentiate between species, structural parts or modifications 28,29,56 . Table 3.…”

Section: Resultsmentioning

confidence: 71%

“…www.nature.com/scientificreports www.nature.com/scientificreports/ So far, pore size determination on dry wood was performed by applying Barrett-Joyner-Halenda (BJH) method or density functional theory (DFT) to sorption isotherms 18,27,29 . This can only be done when the pore shape is known or can be assessed by other methods 13,58 .…”

Section: Resultsmentioning

confidence: 99%

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Determination of mesopores in the wood cell wall at dry and wet state

Nopens

Sazama

König

et al. 2020

Sci Rep

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Wood porosity is of great interest for basic research and applications. one aspect is the cell wall porosity at total dry state. When water is absorbed by wood, the uptake of water within the cell wall leads to a dimension change of the material. A hypothesis for possible structures that hold the water is induced cell wall porosity. nitrogen and krypton physisorption as well as high pressure hydrogen sorption and thermoporosimetry were applied to softwood and hardwood (pine and beech) in dry and wet state for determining surface area and porosity. physisorption is not able to detect pores or surface area within the cell wall. Krypton physisorption shows surface area up 5 times lower than nitrogen with higher accuracy. With high pressure sorption no inaccessible pore volumes were seen at higher pressures. thermoporosimetry was not able to detect mesopores within the hygroscopic water sorption region. Physisorption has to be handled carefully regarding the differences between adsorptives. The absence of water-induced mesopores within the hygroscopic region raise doubts on existing water sorption theories that assume these pore dimensions. When using the term "cell wall porosity", it is important to distinguish between pores on the cell wall surface and pores that exist because of biological structure, as there are no water-induced mesopores present. The finding offers the possibility to renew woodwater-sorption theories because based on the presented results transport of water in the cell wall must be realized by structures lower than two 2 nm. Nanoporous structures in wood at wet state should be investigated more intensively in future. Wood is used for a wide range of applications like furniture, construction components or composites. To increase the usage of wood in products with higher technical requirements (reinforced or functionalized materials), understanding of the basic structure is crucial. Water governs the properties as well as the structure of wood at different climate conditions. Free water molecules from the ambient atmosphere try to gain equilibrium with water molecules in wood cell wall. In the range between 0 and close to 100% relative humidity, water absorption and desorption takes place, leading to different equilibrium moisture contents. The water sorption in this hygroscopic region leads to a deformation of the cell wall, commonly called swelling and shrinking. Therefore the term absorption is used 1. At a certain level, which is individual for each species, saturation of the wooden cell wall with water is reached. Above this so-called fiber saturation point added water remains outside the cell wall, either in the cell lumina or in other biological structures like pits. Wood cell walls contain cellulose, hemicellulose, lignin and various other organic and inorganic molecules, which are characteristic for each species. Despite the knowledge of these compounds, less information is available on the structural organization of all components on molecular level. Hydroxyl groups of cellulose, hemicel...

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“…The intracellular distribution of extractives may affect decay resistance, though there are few studies examining this (Taylor et al 2002). WRC extractives are been detected within tracheid walls (Shi and Avramidis 2018) and it has been hypothesized that the presence of these compounds in the tracheid wall may contribute to the wood's hygroscopic and fungal resistance properties (Stirling and Morris 2016).…”

Section: Introductionmentioning

confidence: 99%

Characterization of pacific silver fir impregnated with extractives from western redcedar

Stirling

Kus

2019

Maderas, Cienc. tecnol.

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Alternative and higher value uses are needed for residual materials generated from wood products processing. Western redcedar sawdust contains an array of unique chemicals and has the potential to be used to alter the appearance, stability and durability of non-durable timbers. Here it was hypothesized that impregnation of Western redcedar heartwood extractives into Pacific silver fir would decrease shrinkage, hygroscopicity, and susceptibility to decay. Western redcedar hot water extracts were obtained from sawdust and used to pressure-treat Pacific silver fir blocks. Extractive impregnation enhanced the wood's appearance and gave it a more cedar-like brown colour. Impregnated samples had reduced shrinkage, but were not as dimensionally stable as Western redcedar heartwood. Pacific silver fir blocks impregnated with water-soluble extractives were also highly susceptible to leaching, and leached samples had similar shrinkage values to untreated controls. In contrast, leaching had little effect on the hygroscopicity of the Western redcedar heartwood. Extractive-impregnated Pacific silver fir blocks had increased resistance to decay by two brown-rot fungi, and showed resistance similar to that of Western redcedar heartwood. However, leached blocks did not have the same decay resistance.

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Dried cell wall nanopore configuration of Douglas-fir, western red cedar and aspen heartwoods

Cited by 21 publications

References 36 publications

Self‐Densification of Highly Mesoporous Wood Structure into a Strong and Transparent Film

Self‐Densification of Highly Mesoporous Wood Structure into a Strong and Transparent Film

Determination of mesopores in the wood cell wall at dry and wet state

Characterization of pacific silver fir impregnated with extractives from western redcedar

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