The toughness of hygrothermally modified wood

Hughes, Mark; Hill, Callum A. S.; Pfriem, Alexander

doi:10.1515/hf-2014-0184

Cited by 41 publications

(32 citation statements)

References 85 publications

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“…This improvement was attributed to the lower equilibrium moisture content of the thermally modified timber when placed in service conditions. Huges et al (2015) provided a thorough description of the effect of thermal modification on the mechanical properties of timber, especially toughness properties, and the vital role of water and its interaction with the cell wall components.…”

Section: Physical Changes In Wood Due To Thermal Processingmentioning

confidence: 99%

Wood modification technologies - a review

Sandberg¹,

Kutnar²,

Mantanis³

2017

iForest

353

197

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The market for new durable products of modified wood has increased substantially during the last few years, especially in Europe. This increased interest depends partly on the restricted use of toxic preservatives due to increased environmental concern, as well as the need for reduced maintenance for wood products that are mainly for exterior use. Furthermore, as sustainability becomes a greater concern, the environmental impact of construction and interior materials should be included in planning by considering the entire life cycle and embodied energy of the materials used. As a result, wood modification has been implemented to improve the intrinsic properties of wood, widen the range of sawn timber applications, and acquire the form and functionality desired by engineers, without bringing environmental friendliness into question. The different wood modification processes are at various stages of development, and the challenges that must be overcome to expand to industrial applications differ amongst them. In this paper, three groups of wood modification processes are discussed and exemplified with modified wood products that have been newly introduced to the market: (i) chemical processing (acetylation, furfurylation, resin impregnation etc.); (ii) thermo-hydro processing (thermal treatment); and (iii) thermo-hydro-mechanical processing (surface densification). Building on these examples, the paper will discuss the environmental impact assessment of modification processes and further development needs.

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Section: Physical Changes In Wood Due To Thermal Processingmentioning

confidence: 99%

Wood modification technologies - a review

Sandberg¹,

Kutnar²,

Mantanis³

2017

iForest

353

197

View full text Add to dashboard Cite

show abstract

“…However, these methods may also introduce new issues, such as poor compatibility with commonly used wood adhesives, wood component degradation, and difficulty in controlling the distribution of the modifier. Fundamentally, the chemical components of wood and its microstructure are key factors affecting wood properties . Undoubtedly, each component plays a crucial role in the physical and mechanical properties of wood.…”

Section: Introductionmentioning

confidence: 99%

“…Fundamentally, the chemical components of wood and its microstructure are key factors affecting wood properties. [11,12] Undoubtedly, each component plays a crucial role in the physical and mechanical properties of wood. However, the amorphous cellulose and matrix contain many hydroxyl and carboxyl groups that have a strong affinity for moisture, which result in deformation and cracking in response to varying relative humidity, and to fungal decay.…”

Section: Introductionmentioning

confidence: 99%

Thermal properties enhancement of poplar wood by substituting poly(furfuryl alcohol) for the matrix

Dong

et al. 2019

Polymer Composites

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Using high‐performance polymers to replace the weak points in wood may be an efficient approach to overcoming certain drawbacks while improving the properties of wood. This study investigated the feasibility of easily replacing part of the wood matrix in poplar wood with renewable poly(furfuryl alcohol) (PFA). The wood was first treated with an alkali solution and was then immersed in a furfuryl alcohol (FA) solution followed by in situ polymerization. After delignification, a large part of hemicelluloses and lignin were removed. In addition, wood porosity increased and more PFA was polymerized in the wood cell walls, resulting in increased weight percent gain and efficient bulking. The thermogravimetric analysis results indicated that the reformation strongly affected the wood thermal stability. A transformation with 30% FA maintained the porous structure of the wood and resulted in the highest maximum degradation temperature. The dynamic mechanical analysis results also indicated that reformation allowed for greater stress transfer at the interface and resulted in a lower damping peak and a higher storage modulus. Our approach, therefore, could provide a promising method to enhance the performance of wood by reforming the wood components and structures.

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“…This enables the use of European wood species in exterior applications [1]. However, HT is a balance between improving the dimensional stability [3] and the resistance to decay fungi [4,5] of wood on the one hand, while reducing its strength and ductility on the other hand [6][7][8][9]. The latter causes problems in load-bearing applications, and can also be the result of heat-induced chemical changes during re-drying of fire-retardant-treated wood [10], or hot-pressing of wood composites [11].…”

Section: Introductionmentioning

confidence: 99%

The effect of de- and re-polymerization during heat-treatment on the mechanical behavior of Scots pine sapwood under quasi-static load

Altgen

Uimonen

Rautkari

2018

Polymer Degradation and Stability

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Loss in strength and ductility is a major drawback for the heat-treatment of solid wood. Previous studies focused mainly on the de-polymerization of cell wall constituents as a cause and the importance of the preferential removal of hemicelluloses. This study tested the hypothesis that the mechanical behavior of wood is additionally affected by re-polymerization reactions within the cell wall matrix during heat-treatment. This was achieved by comparing changes in chemical composition, FT-IR spectra, and mechanical properties of Scots pine sapwood that was heattreated in either dry state in superheated steam or in wet state using pressurized hot water. Although preferential de-polymerization of hemicelluloses was evident for both heat-treatment techniques, the analysis of the chemical composition and FT-IR spectroscopy indicated additional re-polymerization reactions within the cell wall matrix of dry heat-treated wood. The consequent formation of covalent bonds and cross-links increased the resistance against compression loads and hindered inelastic deformation during bending. This resulted in an additional reduction in bending strength and strain energy density of dry compared to wet heat-treated wood. Repolymerization reactions during heat-treatments of wood in dry state were suggested as the main cause for the brittle failure under bending loads, while the effect of hemicellulose-removal on brittleness was much smaller than stated previously.

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The toughness of hygrothermally modified wood

Cited by 41 publications

References 85 publications

Wood modification technologies - a review

Wood modification technologies - a review

Thermal properties enhancement of poplar wood by substituting poly(furfuryl alcohol) for the matrix

The effect of de- and re-polymerization during heat-treatment on the mechanical behavior of Scots pine sapwood under quasi-static load

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