Effect of hemp oil impregnation and thermal modification on European beech wood properties

Abstract Thermal modification is a well established method to improve the dimensional stability and the durability for outdoor use of wood. Unfortunately, these improvements are usually accompanied with a deterioration of mechanical performance (e.g., reduced strength or higher brittleness). In contrast, our investigations of the hardness properties in the longitudinal direction of beech wood revealed a significant improvement with thermal modification. Furthermore, we applied instrumented indentation tests on different hierarchical levels of wood structure (growth ring and cell wall level) to gain closer insights on the mechanisms of thermal treatment of wood on mechanical properties. This approach provides a variety of mechanical data (e.g., elastic parameters, hardness parameters, and viscoelastic properties) from one single experiment. Investigations on the influence of thermal treatment on the mechanical properties of beech revealed similar trends on the growth ring as well as the on the cell wall level of the wood structure.

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Hygroscopic properties of thermally modified false Iroko [Antiaris toxicara (Lesch)]

Journal of Agriculture Forestry and the Social Sciences ◽

10.4314/joafss.v18i1.7 ◽

2021 ◽

Vol 18 (1) ◽

pp. 51-57

Author(s):

F.A. Faruwa ◽

K. Duru

Keyword(s):

Weight Loss ◽

Dimensional Stability ◽

Thermal Process ◽

Colour Change ◽

Wood Properties ◽

Thermal Modification ◽

Hygroscopic Properties ◽

Different Temperatures ◽

Thermally Modified Wood ◽

Modified Wood

The study investigated the use of thermal modification to improve the hygroscopic properties of False Iroko [Antiaris toxicaria (Lesch)]. Samples of Antiaris toxicara Lesch wood were subjected to thermal modification in a furnace at temperatures of 160, 180 and 200°C for 30 and 60 minutes. Results showed that wood properties were improved with exposure to different temperatures. Subsequent to the thermal process, a colour change from pale yellow to darkish brown was observed progressively with increase in temperature, accompanied by a weight loss in the range of 12.08% to 23.67%. The outcome of these treatments resulted in a decrease in volumetric swelling and increase in dimensional stability of modified wood; this can be attributed to observed decrease in moisture intake. The thermal modification of Antiaris toxicara Lesch wood affected the dimensional stability properties. Thus, due to significant changes via modification carried out on the selected species which is classified as lesser utilized wood species, lesser utilized wood,Antiaristoxicara Lesch wood is recommended for use due to its efficient dimensional stability after modification . keywords:, Thermally modified wood ;False Iroko

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Influence of process conditions on hygroscopicity and mechanical properties of European beech thermally modified in a high-pressure reactor system

Holzforschung ◽

10.1515/hf-2015-0235 ◽

2016 ◽

Vol 70 (10) ◽

pp. 971-979 ◽

Cited By ~ 18

Author(s):

Michael Altgen ◽

Holger Militz

Keyword(s):

Mechanical Properties ◽

Cell Wall ◽

European Beech ◽

Wood Properties ◽

Reactor System ◽

Bending Test ◽

Process Conditions ◽

Dynamic Vapor Sorption ◽

Property Changes ◽

Closed Reactor

Abstract European beech (Fagus sylvatica L.) was thermally modified in a closed reactor system under various process conditions. Sorption cycles, dynamic vapor sorption (DVS) measurements, and a three-point bending test were performed on thermally modified wood (TMW) to assess hygroscopicity and mechanical properties. As a function of mass loss (ML), the initial equilibrium moisture content (EMC) measured at 20°C/65% relative humidity (RH) directly after the process was strongly influenced by the RH during the process. This effect is explained by realignments of amorphous polymers in the cell wall ultra-structure in the course of thermal modification (TM). However, the EMC of TMW gradually increased after sorption cycles consisting of conditioning over liquid water and water-soaking. This increase was most distinct for TMW modified at low RH, which is an indication for reversible ultra-structural realignments. Results of the bending test suggest that structural realignments also hindered the plastic flow of amorphous cell wall polymers, thereby reducing inelastic toughness and inelastic deflection, while other bending properties were solely affected by ML alone. Process conditions in a closed reactor systems have a profound impact on resulting wood properties, and thus, the partial reversibility of these property changes need to be considered during the application.

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The Impact of Paraffin-Thermal Modification of Beech Wood on Its Biological, Physical and Mechanical Properties

Forests ◽

10.3390/f10121102 ◽

2019 ◽

Vol 10 (12) ◽

pp. 1102 ◽

Cited By ~ 3

Author(s):

Ladislav Reinprecht ◽

Miroslav Repák

Keyword(s):

Mechanical Properties ◽

Bending Strength ◽

Beech Wood ◽

Physical And Mechanical Properties ◽

Brown Rot ◽

European Beech ◽

White Rot ◽

White Rot Fungus ◽

Poria Placenta ◽

The Impact

The European beech (Fagus sylvatica L.) wood was thermally modified in the presence of paraffin at the temperatures of 190 or 210 °C for 1, 2, 3 or 4 h. A significant increase in its resistance to the brown-rot fungus Poria placenta (by 71.4%–98.4%) and the white-rot fungus Trametes versicolor (by 50.1%–99.5%) was observed as a result of all modification modes. However, an increase in the resistance of beech wood surfaces to the mold Aspergillus niger was achieved only under more severe modification regimes taking 4 h at 190 or 210 °C. Water resistance of paraffin-thermally modified beech wood improved—soaking reduced by 30.2%–35.8% and volume swelling by 26.8%–62.9% after 336 h of exposure in water. On the contrary, its mechanical properties worsened—impact bending strength decreased by 17.8%–48.3% and Brinell hardness by 2.4%–63.9%.

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Effect of Moderate Temperature Thermal Modification Combined with Wax Impregnation on Wood Properties

Applied Sciences ◽

10.3390/app10228231 ◽

2020 ◽

Vol 10 (22) ◽

pp. 8231

Author(s):

Jing-Wen Zhang ◽

Hong-Hai Liu ◽

Lin Yang ◽

Tian-Qi Han ◽

Qin Yin

Keyword(s):

Mechanical Strength ◽

Dimensional Stability ◽

Color Change ◽

Strength Loss ◽

Wood Properties ◽

Thermal Modification ◽

Moderate Temperature ◽

Modulus Of Rupture ◽

Internal Surfaces ◽

Higher Temperature

Thermal modification (TM) improves the hydrophobicity, dimensional stability, and durability of wood, but TM commonly results in severe color change and mechanical strength loss as wood is treated at higher temperature. In this study, Pterocarpus macrocarpus Kurz wood was thermally modified at moderate temperature (150 °C) and higher temperature (200 °C), and subsequently TM wood at 150 °C was subjected to wax impregnation (WI), the effect of a combination of TM and WI on the hygroscopicity, dimensional stability, and mechanical properties, as well as the micro-structure of wood, were investigated and compared. The results showed that the mass loss of wood was slight at 150 °C TM, while it became severe at 200 °C TM conditions. TM conditions affected the amount of the subsequent wax impregnation; the equilibrium moisture content (EMC), water absorption ratio, and adsorption and absorption swelling of the 150 °C TM + WI group were lower than that of 200 °C TM, and presented the lowest value. Moderate temperature TM could improve the hydrophobicity and dimensional stability of wood, but WI played a key role in the improvement. TM decreased the modulus of rupture (MOR) of wood, while WI improved the MOR. TM increased the modulus of elasticity (MOE) of wood, but WI had little effect on MOE; Scanning electron microscope (SEM) observation showed that the wax was successfully impregnated into the wood interior, and presented an even distribution on the internal surfaces of wood cells; Fourier-transform infrared spectroscopy (FTIR) spectra verified the changes of –OH and C=O after TM and TM + WI, which contributed to decreasing hygroscopicity and improving the dimensional stability of the wood. Impregnated wax improved wood mechanical strength, but decreased the lightness, and deepened the color of wood. The combination of thermal modification at moderate temperature with subsequent wax impregnation is a practical approach for improving wood properties.

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Crown structure of European beech (Fagus sylvatica L.): a non-causal proxy for mechanical–physical wood properties

Canadian Journal of Forest Research ◽

10.1139/cjfr-2020-0382 ◽

2020 ◽

Author(s):

Andreas Rais ◽

Martin Jacobs ◽

Jan-Willem G. van de Kuilen ◽

Hans Pretzsch

Keyword(s):

Fagus Sylvatica ◽

Laser Scanning ◽

European Beech ◽

Wood Properties ◽

Projection Area ◽

Mixed Stands ◽

Crown Volume ◽

Crown Structure ◽

Crown Morphology ◽

Crown Projection Area

The current tendency towards the silvicultural promotion of mixed tree species has increased the variability in the crown structure within stands. This study shows how neighbouring trees can influence both the external crown features and internal wood properties of trees. Using terrestrial laser scanning, the crown features of 100 European beech trees, Fagus sylvatica L., from pure beech stands and mixed stands of beech with Douglas fir, Norway spruce, sessile oak and Scots pine were recorded. After felling and sawing, the dynamic modulus of elasticity was determined on 1623 boards from the two lower 4.1-m logs. Significant differences were found between beech trees from pure stands and those from beech–pine mixed stands in terms of crown volume (415 m3 vs 766 m3), crown ratio (50.0% vs 71.5%), crown projection ratio (0.182 m cm−1 vs 0.253 m cm−1) and branch angle (30.7° vs 54.1°). Multiple regression mixed models revealed significant relationships between timber stiffness and crown volume (-1.7 N mm−2 m−3), crown ratio (-28.4 N mm−2 %−1) and crown projection area (-9835 N mm−2 m−1 cm). Thus, the crown morphology of broad-leaved species reflects the tree’s long-term competitive status and suggests indicators for the assessment of mechanical–physical wood properties.

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Investigations on densified beech wood for application as a swelling dowel in timber joints

Holzforschung ◽

10.1515/hf-2018-0106 ◽

2019 ◽

Vol 73 (6) ◽

pp. 559-568 ◽

Cited By ~ 3

Author(s):

Philippe Grönquist ◽

Thomas Schnider ◽

Andreas Thoma ◽

Fabio Gramazio ◽

Matthias Kohler ◽

...

Keyword(s):

Beech Wood ◽

Compressive Loading ◽

Swelling Pressure ◽

European Beech ◽

Densified Wood ◽

Robotic Fabrication ◽

Recovery Capacity ◽

Pressure Development ◽

Multiple Cycles ◽

Wooden Structures

AbstractFor robotic fabrication of wooden structures, the simple, quick and tight joining of elements can be solved using swelling hardwood dowels. This topic has been the focus of the present study, and the set-recovery capacity of densified wood (dW) as dowel material was investigated. European beech was compressed in the radial direction at 103°C and 10% moisture content (MC) to a compression ratio of 40%. Multiple swelling and shrinkage cycles were applied to measure swelling behavior, swelling pressure development and combined swelling and creep under compressive loading. It has been demonstrated that dW shows increased swelling and more persisting swelling pressures than native wood (nW). The set-recovery prevents significant contact-stress relaxation over multiple cycles of MC change. Application as a structural joining element for robotic fabrication was studied by shear lap joint tests on round double-dovetail swelling dowels.

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Influence of Thermal Modification on Surface Properties and Chemical Composition of Beech Wood (Fagus sylvatica L.)

Drvna industrija ◽

10.5552/drind.2016.1520 ◽

2016 ◽

Vol 67 (1) ◽

pp. 65-71 ◽

Cited By ~ 3

Author(s):

Josip Miklečić ◽

Vlatka Jirouš-Rajković

Keyword(s):

Chemical Composition ◽

Surface Properties ◽

Fagus Sylvatica ◽

Beech Wood ◽

Thermal Modification ◽

Fagus Sylvatica L

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Mineralization of wood by calcium carbonate insertion for improved flame retardancy

Holzforschung ◽

10.1515/hf-2015-0228 ◽

2016 ◽

Vol 70 (9) ◽

pp. 867-876 ◽

Cited By ~ 33

Author(s):

Vivian Merk ◽

Munish Chanana ◽

Sabyasachi Gaan ◽

Ingo Burgert

Keyword(s):

Hybrid Materials ◽

Beech Wood ◽

Three Dimensional ◽

European Beech ◽

Electrolyte Solutions ◽

Cone Calorimetry ◽

Mineral Phases ◽

Novel Material ◽

Combustion Flow ◽

Highly Porous

Abstract Wood can be considered as a highly porous, three-dimensional organic scaffold. It can be mineralized to create hierarchically structured organic-inorganic hybrid materials with novel properties. In the present paper, the precipitation of CaCO3 mineral in Norway spruce and European beech wood has been studied by alternating impregnation with aqueous and alcoholic electrolyte solutions. Microstructural imaging by SEM and confocal Raman microscopy shows the distribution of calcite and vaterite as two CaCO3 polymorphs, which are deposited deep inside the cellular structure of the wood. The confined microenvironment of the wood cell wall seems to favor a formation of vaterite, as visible by XRD and Raman spectroscopy. In view of a practical application, the mineralization of wood opens up ways for sustainable wood-based hybrid materials with a significantly improved fire resistance, as proven via pyrolysis combustion flow calorimetry and cone calorimetry tests. Beyond that, this versatile solute-exchange approach provides an opportunity for the incorporation of a broad range of different mineral phases into wood for novel material property combinations.

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CHANGE OF WOOD PROPERTIES IN THERMAL MODIFICATION

FORESTRY BULLETIN ◽

10.18698/2542-1468-2018-1-94-99 ◽

2018 ◽

Author(s):

М.Г. Ермоченков ◽

◽

А.Г. Евстигнеев ◽

Keyword(s):

Wood Properties ◽

Thermal Modification

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