Sorption and diffusion properties of untreated and thermally modified beech wood dust

AbstractDynamic water vapor sorption experiments were carried out using beech wood dust (from untreated and thermally modified wood) of two-particle sizes, (< 25 and 80–250 µm), obtained from abrasive sanding. Sorption isotherms were parameterized with the GAB and GDW models. Dust from thermally modified wood had significantly lower equilibrium moisture content compared to dust from untreated material, due to the reduction in primary sorption sites in treated material. The observed changes were quantified by the coefficients of the GAB and GDW models. Thermal modification and size of wood dust particles had no influence on binding energy of water molecules being linked to the secondary sorption sites. Water diffusivity decreased significantly with increasing moisture content, but only for monolayer sorption. For higher moisture content values, water diffusivity was practically independent of moisture content. These results were found for untreated and thermally modified material as well as for both dust size fractions. The influence of thermal modification on water diffusivity was unclear, which is attributed to the diffusion model, which represents dust particles as spheres and assumes instant hygroscopic equilibrium. Overall, this study indicates that the effectiveness of filtration processes likely depends strongly on sorption and diffusion properties of wood dust only at low moisture contents within the hygroscopic range.

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Occupational Exposure to Dust Produced when Milling Thermally Modified Wood

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17051478 ◽

2020 ◽

Vol 17 (5) ◽

pp. 1478 ◽

Cited By ~ 9

Author(s):

Alena Očkajová ◽

Martin Kučerka ◽

Richard Kminiak ◽

Ľuboš Krišťák ◽

Rastislav Igaz ◽

...

Keyword(s):

Feed Rate ◽

Dust Particles ◽

Wood Dust ◽

International Agency ◽

Oak Wood ◽

Granular Composition ◽

Spruce Wood ◽

Thermally Modified Wood ◽

Unmodified Wood ◽

Modified Wood

During production, thermally modified wood is processed using the same machining operations as unmodified wood. Machining wood is always accompanied with the creation of dust particles. The smaller they become, the more hazardous they are. Employees are exposed to a greater health hazard when machining thermally modified wood because a considerable amount of fine dust is produced under the same processing conditions than in the case of unmodified wood. The International Agency for Research on Cancer (IARC) states that wood dust causes cancer of the nasal cavity and paranasal sinuses and of the nasopharynx. Wood dust is also associated with toxic effects, irritation of the eyes, nose and throat, dermatitis, and respiratory system effects which include decreased lung capacity, chronic obstructive pulmonary disease, asthma and allergic reactions. In our research, granular composition of particles resulting from the process of longitudinal milling of heat-treated oak and spruce wood under variable conditions (i.e., the temperature of modification of 160, 180, 200 and 220 °C and feed rate of 6, 10 and 15 m.min−1) are presented in the paper. Sieve analysis was used to determine the granular composition of particles. An increase in fine particle fraction when the temperature of modification rises was confirmed by the research. This can be due to the lower strength of thermally modified wood. Moreover, a different effect of the temperature modification on granularity due to the tree species was observed. In the case of oak wood, changes occurred at a temperature of 160 °C and in the case of spruce wood, changes occurred at the temperatures of 200 and 220 °C. At the temperatures of modification of 200 and 220 °C, the dust fraction (i.e., that occurred in the mesh sieves, particles with the size ≤ 0.08 mm) ranged from 2.99% (oak wood, feed rate of 10 m.min−1) to 8.07% (spruce wood, feed rate of 6 m.min−1). Such particles might have a harmful effect on employee health in wood-processing facilities.

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Water sorption and diffusion properties of beech wood dust

Powder Technology ◽

10.1016/j.powtec.2019.02.007 ◽

2019 ◽

Vol 346 ◽

pp. 109-115 ◽

Cited By ~ 1

Author(s):

Jerzy Majka ◽

Tomasz Rogoziński ◽

Wiesław Olek

Keyword(s):

Water Sorption ◽

Beech Wood ◽

Wood Dust ◽

And Diffusion ◽

Diffusion Properties

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Sorption isotherms of thermally modified wood

Holzforschung ◽

10.1515/hf-2011-0260 ◽

2013 ◽

Vol 67 (2) ◽

pp. 183-191 ◽

Cited By ~ 32

Author(s):

Wiesław Olek ◽

Jerzy Majka ◽

Łukasz Czajkowski

Keyword(s):

Water Vapor ◽

Moisture Content ◽

Equilibrium Moisture Content ◽

Sorption Isotherms ◽

European Beech ◽

Thermal Modification ◽

Type Ii ◽

Hygroscopic Properties ◽

Thermally Modified Wood ◽

Modified Wood

Abstract The hygroscopic properties of thermally modified wood have been studied in terms of adsorption and desorption processes. Poplar (Populus spp.) and European beech (Fagus sylvatica L.) were in focus. The obtained isotherms were parameterized with the models of Hailwood-Horrobin, Guggenheim-Anderson-deBoer, generalized D’Arcy and Watt, and Yanniotis and Blahovec. The changes in equilibrium moisture content (EMC) were quantified, and the accessibility of water vapor to the sorption sites was determined. The monolayer and multilayer sorption was studied and the sorption isotherms were classified. All sorption isotherms were type II, and the type was not changed after the modification. The monolayer sorption was found to be responsible for the reduction in EMC after thermal modification. The observed increase in the hysteresis coefficient was explained by the reorganization of the wood ultrastructure.

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Flammability Characteristics of Thermally Modified Meranti Wood Treated with Natural and Synthetic Fire Retardants

Polymers ◽

10.3390/polym13132160 ◽

2021 ◽

Vol 13 (13) ◽

pp. 2160

Author(s):

Milan Gaff ◽

Hana Čekovská ◽

Jiří Bouček ◽

Danica Kačíková ◽

Ivan Kubovský ◽

...

Keyword(s):

Burning Rate ◽

Flame Retardants ◽

Thermal Modification ◽

Positive Contribution ◽

Spearman Correlation ◽

Chemical Changes ◽

Combustion Properties ◽

Flammability Characteristics ◽

Thermally Modified Wood ◽

Modified Wood

This paper deals with the effect of synthetic and natural flame retardants on flammability characteristics and chemical changes in thermally treated meranti wood (Shorea spp.). The basic chemical composition (extractives, lignin, holocellulose, cellulose, and hemicelluloses) was evaluated to clarify the relationships of temperature modifications (160 °C, 180 °C, and 210 °C) and incineration for 600 s. Weight loss, burning speed, the maximum burning rate, and the time to reach the maximum burning rate were evaluated. Relationships between flammable properties and chemical changes in thermally modified wood were evaluated with the Spearman correlation. The thermal modification did not confirm a positive contribution to the flammability and combustion properties of meranti wood. The effect of the synthetic retardant on all combustion properties was significantly higher compared to that of the natural retardant.

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Colour stability of surface finishes on thermally modified beech wood

Annals of WULS, Forestry and Wood Technology ◽

10.5604/01.3001.0015.2391 ◽

2021 ◽

Vol 114 ◽

pp. 116-124

Author(s):

Gabriela Slabejová ◽

MÁRIA ŠMIDRIAKOVÁ

Keyword(s):

Surface Finish ◽

Beech Wood ◽

Surface Finishing ◽

Colour Stability ◽

Colour Difference ◽

Surface Finishes ◽

Before And After ◽

Thermally Modified Wood ◽

Wood Surfaces ◽

Modified Wood

Colour stability of surface finishes on thermally modified beech wood. The paper deals with the influence of the type of transparent surface finish on the change of colour of the surfaces of native beech wood and thermally modified wood. At the same time, the colour stability of three surface finishes on the surfaces of native and thermally modified beech wood was monitored. Beech wood was thermally modified at temperature of 125 °C for 6 hours. The thermal treatment was performed in a pressure autoclave APDZ 240, by the company Sundermann s.r.o in Banská Štiavnica. Three various types of surface finishes (synthetic, wax-oil, water-based) were applied onto the wood surfaces. The colour of the surfaces of native wood and thermally modified wood was measured in the system CIELab before and after surface finishing; the coordinates L*, a*, b*, C*ab and h*ab were measured. From the coordinates measured before and after surface finishing, the differences were calculated and then the colour difference ∆E* was calculated. Subsequently, the test specimens with the surface finishes were exposed to natural sunlight, behind glass in the interior for 60 days. The surface colour was measured at specified time of the exposure (10, 20, 30, 60 days). The results showed that the colour of the wood surfaces changed after application of the individual surface finishes; and the colour difference reached a change visible with a medium quality filter up to a high colour difference. The wax-oil surface finish caused a high colour difference on native wood and on thermally modified wood as well. On native beech wood, the lowest colour difference after exposure to sunlight was noticeable on the synthetic surface finish. On the surface of wood thermally modified, after exposure to sunlight, the lowest colour difference was noticeable on the surface with no surface finish.

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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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Thermal modification of Southern pine combined with wax emulsion preimpregnation: effect on hydrophobicity and dimensional stability

Holzforschung ◽

10.1515/hf-2014-0106 ◽

2015 ◽

Vol 69 (4) ◽

pp. 405-413 ◽

Cited By ~ 24

Author(s):

Wang Wang ◽

Yuan Zhu ◽

Jinzhen Cao ◽

Xi Guo

Keyword(s):

Water Absorption ◽

Dimensional Stability ◽

Photoelectron Spectroscopy ◽

Water Repellency ◽

Solid Content ◽

Thermal Modification ◽

Paraffin Wax ◽

Southern Pine ◽

Thermally Modified Wood ◽

Modified Wood

Abstract The aim of this study was to enhance the water repellency and dimensional stability of thermally modified wood by combining the preimpregnation of paraffin wax emulsion. To achieve this, Southern pine (SP; Pinus spp.) samples were first impregnated with paraffin wax emulsion (with 2.0% solid content) and then subjected to thermal modification (TM) in an oven at 180°C and 220°C for 4 and 8 h. The contact angle (CA), surface free energy, water absorption rate (WAR), anti-swelling efficiency (ASE), and bending properties of the control and modified samples were investigated. Moreover, the chemical and morphological alterations were analyzed by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Both the wax impregnation and TM decreased the surface wettability, water absorption, and tangential swelling, while the combination of wax and thermal treatment exhibited the best water repellency and dimensional stability, indicating the synergism between the two procedures. However, the wax preimpregnation did not affect the mechanical properties of thermally modified wood. The FTIR, SEM, and XPS analyses confirmed that the synergistic effect is mainly due to the redistribution of the paraffin wax during TM rather than its impact on the chemical changes caused by thermal degradation.

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Welding of thermally modified wood and thermal modification of the welded wood: Effects on the shear strength under climatic conditions

BioResources ◽

10.15376/biores.16.2.3224-3234 ◽

2021 ◽

Vol 16 (2) ◽

pp. 3224-3234

Author(s):

Mojgan Vaziri ◽

Dick Sandberg

Keyword(s):

Shear Strength ◽

Welded Joints ◽

Negative Influence ◽

Climatic Conditions ◽

Thermal Modification ◽

Modes Of Failure ◽

Computed Tomography Scanning ◽

Thermally Modified Wood ◽

Welding Pressure ◽

Modified Wood

This work investigated how thermal modification affects the shear strength of welded joints under different climatic conditions. The order of the thermal modification, before or after the welding, was investigated for its effect on the shear strength of the welded wood. Two groups of thermally modified specimens were prepared in a laboratory kiln under controlled conditions, one thermally modified before welding and the other after welding of the specimens. The shear strength of the specimens were measured at four different moisture contents of 10%, 12%, 16%, and 18%, and the results for the two different approaches were compared. Moreover, observations of the X-ray computed tomography scanning and digital microscopy were used to study the density profile and the structural details of the welded joints. The results showed that thermal treatment of the wood either before or after welding had a negative influence on the shear strength, and the modes of failure of the joints in mechanical tests were in most cases brittle. In the weld interface of the wood modified before welding, a rigid material similar to charcoal was produced as a result of the further degradation of wood by welding pressure and frictional motion. Welding of wood before thermal modification, however, yielded thicker and more densified joints with less susceptibility to higher moisture variations than the joints obtained by welding the thermally modified wood.

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Use of Thermo-Modified Wood Massif in Making Parametric Exterior Furniture

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i4.36.25045 ◽

2018 ◽

Vol 7 (4.36) ◽

pp. 1112 ◽

Cited By ~ 3

Author(s):

A. R. Shaikhutdinova ◽

R. R. Safin ◽

F. V. Nazipova ◽

S. R. Mukhametzyanov

Keyword(s):

Treated Wood ◽

Thermal Modification ◽

Saturated Steam ◽

Polished Surface ◽

Duration Of Treatment ◽

Heat Treated ◽

Different Temperatures ◽

Convective Thermal ◽

Thermally Modified Wood ◽

Modified Wood

This paper proposes the use of an array of heat-treated wood of various species to make parametric furniture for the purpose of operation in the exterior, and on objects in conditions of high humidity. The dependence of change in the color range of thermowoods depending on the temperature and duration of treatment is presented. Experiments were carried out to study the biological stability of thermally modified wood treated by various technologies including: vacuum-convective thermal modification in superheated steam, convective thermal modification in high-pressure saturated steam, as well as in hydrophobic liquids, in flue gas and vacuum-conductive thermal-modifying. The degree of resistance of wood was determined, which allows to conclude that the mass losses of heat-treated specimens caused by the destructive action of fungi are significantly lower compared to untreated ones. The researchwas conducted to determine the numerical characteristics of microroughness of the polished surface of wood, thermally modified at different temperatures.

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Influence of Different Modifications on Bending Strength of Wood

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.800.240 ◽

2019 ◽

Vol 800 ◽

pp. 240-245

Author(s):

Andis Antons ◽

Dace Cīrule ◽

Ingeborga Andersone ◽

Anrijs Verovkins ◽

Edgars Kuka

Keyword(s):

Thermal Treatment ◽

Bending Strength ◽

Treatment Method ◽

Thermal Modification ◽

Wood Products ◽

Bending Properties ◽

Wood Protection ◽

Thermally Modified Wood ◽

Mild Temperature ◽

Modified Wood

Despite intensive research in wood protection, no simple wood treatment method is available for satisfactory wood protection that could ensure appropriate strength and bio-resistance of wood products during their service life. The present study is a part of a project that is aimed to improve wood service properties by combining wood thermal treatment and impregnation with copper containing preservatives. The objective of the present study was to investigate the effect of conventional modifications (thermal modification at relatively mild temperature range (150 - 180°C) and impregnation) and double-treatments (impregnation after thermal treatment and vice versa) on the bending properties of birch (Betula spp.) and pine (Pinussylvestris L.) wood. Bending strength considerably decreased after thermal modification of wood, however MOE values generally did not significantly change. Moreover, impregnation had no effect on the bending properties for both unmodified and thermally modified wood specimens. For double-treatment in which impregnation was carried out before thermal modification no changes in bending strength were observed comparing to thermally modified wood. However, MOE values of these specimens were 10 % for birch and 19 % for pine smaller comparing to just thermally modified wood. The results of double-treatment tests imply that, regarding wood bending properties, wood impregnation after thermal modification is more appropriate.

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