scholarly journals Establishment of moisture diffusion regularities through the polymer shell of thermally modified wood

2021 ◽  
Vol 12 (1) ◽  
pp. 41-47
Author(s):  
Yu. V. Tsapko ◽  
O. Yu. Horbachova
Keyword(s):  
Dimensional Stability ◽  
Experimental Studies ◽  
Treated Wood ◽  
Moisture Diffusion ◽  
Wood Products ◽  
Heating Process ◽  
Polymer Shell ◽  
Coating Application ◽  
Thermally Modified Wood ◽  
Modified Wood

An analysis of the process of thermal modification of wood, which was obtained by a controlled heating process, was done. The unique technological properties (durability, low hygroscopicity and dimensional stability) of thermomodified wood make it possible to use it in various scope. Due to the influence of temperature there are some chemical changes in the structures of the wood cell wall components (lignin, cellulose and hemicellulose). This leads to an increase in density, hardness, improved hydrophobicity (water repellency), thereby reducing their ability to absorb moisture and swell. The products absorb moisture gradually, are less prone to swelling and shrinkage, but still need the elastic coatings application. It is proved that heat-treated wood turns gray over time under the influence of sunlight, and therefore requires additional surface treatment with a coating. Additional protective substances application on the thermo-modified wood products surface promotes dimensional stability and protects against rapid weathering of the surface in open air conditions. The use of transparent coatings and oils does not protect the surface from discoloration during weathering. They are recommended for products are manufactured from thermomodified wood, which are operated away from direct sunlight and rain. The parameters of moisture penetration into wood are mathematically modeled on the basis of the moisture diffusion quasi-stationary equation through the polymer coating on the flat sample surface. The dynamics of moisture content changes in thermally modified wood by different schedules parameters has been experimentally studied. The obtained mathematical relations based on the experimental studies results make it possible to calculate the moisture diffusion coefficient in thermally modified wood in the presence of a polymer shell. It is established that the wax coating application on the surface of the product reduces the moisture diffusion process more than 10 times for surfaces treated at a temperature of 160 °C for 1 hour. That is, such products can be used on objects with high humidity.

scholarly journals Increasing the Strength of the Glue Line in the Production of Thermally Modified Wood Paneling

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 253
Author(s):  
Ruslan Rushanovich Safin ◽  
Aigul Ravilevna Shaikhutdinova ◽  
Ruslan Khasanshin ◽  
Shamil Mukhametzyanov ◽  
Albina Safina
Keyword(s):  
Wood Products ◽  
Ultraviolet Rays ◽  
Surface Activation ◽  
Wood Block ◽  
Two Stage ◽  
Adhesion Properties ◽  
Wood Processing ◽  
Ultraviolet Treatment ◽  
Thermally Modified Wood ◽  
Modified Wood

This work is devoted to the study of the effect of ultraviolet rays for the surface activation of pine wood thermally modified at temperatures of 180−240 °C in order to increase the surface roughness, enhance the wettability of thermal wood and the adhesive strength of the glue in the production of wood block furniture panels. Studies were carried out to measure the contact angle of wettability of thermally modified wood samples of pine, as a result of which it was determined that the ultraviolet treatment process contributes to an increase in the adhesion properties of the surface layer of thermally modified wood by more than 13% due to the reactivity of ultraviolet rays to oxidize and degrade ligno-containing wood products. At the same time, the most active process of surface activation takes place during 60 min of ultraviolet irradiation of wood with a total irradiation of at least 125 W/cm2. It was revealed that the combined effect of two-stage wood processing, including preliminary volumetric thermal modification followed by surface ultraviolet treatment, causes an increase in the moisture resistance of glued wood products by 24%. So, if the strength of the glue seam when gluing natural wood samples after boiling decreased by 46%, then the samples that underwent two-stage processing showed a decrease only by 22%. In connection with the results obtained, an improved technology for the production of furniture boards for the manufacture of moisture-resistant wood products is proposed.

A review on life cycle assessments of thermally modified wood

Holzforschung ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Kévin Candelier ◽  
Janka Dibdiakova
Keyword(s):  
Life Cycle ◽  
Environmental Impacts ◽  
Treated Wood ◽  
Single Step ◽  
Thermal Modification ◽  
Wood Products ◽  
Wood Preservation ◽  
Cumulative Energy ◽  
Thermally Modified Wood ◽  
Cumulative Energy Intake

AbstractThis review compiles various literature studies on the environmental impacts associated with the processes of thermal modification of wood. In wood preservation field, the wood modification by heat is considered as an ecofriendly process due to the absence of any additional chemicals. However, it is challenging to find proper scientific and industrial data that support this aspect. There are still very few complete studies on the life cycle assessment (LCA) and even less studies on the environmental impacts related to wood heat treatment processes whether on a laboratory or on an industrial scales. This comprehensive review on environmental impact assessment emphasizes environmental categories such as dwindling of natural resources, cumulative energy intake, gaseous, solid and liquid emissions occurred by the thermal-treated wood industry. All literature-based data were collected for every single step of the process of wood thermal modification like resources, treatment process, transport and distribution, uses and end of life of treated wood products.

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

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

scholarly journals Effects of Shellac Treatment on Wood Hygroscopicity, Dimensional Stability and Thermostability

Coatings ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 881
Author(s):  
Mihaela Liu ◽  
Guanglin Xu ◽  
Jianan Wang ◽  
Xinwei Tu ◽  
Xinyou Liu ◽  
...  
Keyword(s):  
Dimensional Stability ◽  
Moisture Absorption ◽  
Morphological Characteristics ◽  
Treated Wood ◽  
Wood Products ◽  
Control Group ◽  
Water Repellent ◽  
Thermoplastic Resin ◽  
Weight Percentage ◽  
Thermogravimetric Curve

Dimensional stability proves to be an important factor affecting the quality of wooden products. As a sort of crude and thermoplastic resin, shellac excreted by lac insects demonstrates water-repellent and environmental-friendly features. The research impregnated shellac with wood at room temperature and with a vacuum-pressure procedure. Efforts were made to examine how shellac treatment affected the dimensional stability, moisture absorption, chemical structure, thermostability, as well as morphological characteristics of wood. Results indicated that shellac treatment was a type of efficient solution useful in the enhancement of the dimensional stability of wood. Shellac solution had good permeability in the wood, and the weight percentage gain reached 13.01% after impregnation. The swelling coefficients of treated wood in the tangential and radial directions decreased by 20.13% and 24.12%, respectively, indicating that impregnation could improve wood dimensional stability. The moisture absorption of shellac-treated wood was reduced by 38.15% under 20 °C and 65% relative humidity. Moreover, shellac treatment significantly modified wood structure, although there were no drastic changes in the spectra. Specimens for shellac treatment ran across two decomposition peaks at 350 and 390 °C, and specimens in the control group saw one more common derivative thermogravimetric curve when the sharp peak approached 355 °C. After impregnation of shellac into wood, the shellac blocked pits and hardened on the intrinsic layer of the wood for fear of hygroscopicity. The practice was applicable to a variety of wood products, such as buildings, furniture, and landscape architecture.

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

Holzforschung ◽  
2015 ◽  
Vol 69 (4) ◽  
pp. 405-413 ◽  
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.

scholarly journals A comparative study on the effects of linseed oil and shellac treatment on the hygroscopicity, dimensional stability, and color changes of Chinese ash wood

BioResources ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. 8085-8092
Author(s):  
Mihaela Liu ◽  
Xinwei Tu ◽  
Xinyou Liu ◽  
Zhihui Wu ◽  
Jiufang Lv ◽  
...  
Keyword(s):  
Dimensional Stability ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Moisture Absorption ◽  
Linseed Oil ◽  
Morphological Characteristics ◽  
Treated Wood ◽  
Water Repellency ◽  
Wood Products ◽  
Color Changes

Linseed oil and shellac are natural, environmentally friendly materials with good water repellency. They were used to impregnate Chinese ash wood at room temperature (20 °C) using a vacuum-pressure procedure (consisting of three cycles of 0.01 MPa for 1.5 h and atmospheric pressure for 1.5 h) to improve the dimensional stability of wood. The effects of the impregnation treatment on wood color changes, dimensional stability, moisture absorption, and morphological characteristics were evaluated. The linseed oil and shellac treatment improved the dimensional stability of wood. Linseed oil and shellac displayed good permeability in Chinese ash wood, with weight gains of 21.7% and 19.0%, respectively, after impregnation. The swelling coefficients of treated wood in the tangential and radial directions decreased by 15 to 22%, indicating that impregnation improved the dimensional stability of wood. Linseed oil and shellac solidified and occluded the pits within the wood interior to prevent moisture absorption. This method can be used to improve the dimensional stability of a variety of wood products, such as buildings, furniture, and landscape architecture.

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

2018 ◽  
Vol 7 (4.36) ◽  
pp. 1112 ◽  
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.   

scholarly journals Establishment of the regularities of the polymer cover influence on the wood bio destruction

2021 ◽  
Vol 12 (4) ◽  
Author(s):  
Yu. V. Tsapko ◽  
O. Yu. Horbachova ◽  
S. M. Mazurchuk
Keyword(s):  
Weight Loss ◽  
Untreated Wood ◽  
Water Repellent ◽  
Maximum Weight ◽  
Polymer Shell ◽  
Wood Protection ◽  
Thermally Modified Wood ◽  
Wooden Structures ◽  
Modified Wood ◽  
Maximum Weight Loss

The process of wood biological destruction is analyzed. It was found that the neglect of environmentally friendly means of bioprotection, leads to the destruction of wooden structures under the action of microorganisms. It is established that the study of wood protection conditions leads to the creation of new types of protective materials that reduce water absorption, as well as reduce the amount of substances that are the environment for the development of wood-destroying fungi. In this regard, a computational and experimental method for determining the proportion of destroyed material under the action of microorganisms using an antiseptic has been developed. The analysis of the results shows that the maximum weight loss in the case of biodegradation of untreated wood samples ranged from 7,6 to 16 %, and the weight loss of thermally modified wood samples did not exceed 3 %, antiseptic-hydrophobicizer – was less than 2 %. It was found that the protection when treated with thermally modified wood with oil-wax and azure exceeds (compared to untreated) more than 4 times in terms of biodegradation, and treatment with antiseptic-water repellent for untreated oil-wax and azure – more than 8 times. It should be noted that the presence of oil-wax and azure leads to blockage of the wood surface from the penetration of moisture or microorganisms. Therefore, the intensity of wood-destroying fungus development on the surface of various samples are differed. Obviously, such a mechanism of the protective coating influence is the factor regulating the process, which preserves the integrity of the object. On the experimental data basis and by modeling the equations, the microorganisms population dynamics in the volume of material and the function of increasing the number of dead organisms are derived. Thus, a polymer shell was created on the surface of the sample, which significantly reduced the penetration of microorganisms into the wood, and the weight loss of wood during biodegradation did not exceed 2,5 %. Additional application of protective substances on the surface increases the protection level of untreated pine wood by 72 %, thermomodified at 190 °C – 25 %, at 220 °C – by 37 %. Similar results for hornbeam wood – 60; 37 and 28 %, for oak – 50; 37 and 37 % respectively.

Influence of Different Modifications on Bending Strength of Wood

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.

Evaluation of water related properties of birch wood products modified with different molecular weight phenol-formaldehyde oligomers

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Juris Grinins ◽  
Vladimirs Biziks ◽  
Janis Rizikovs ◽  
Ilze Irbe ◽  
Holger Militz
Keyword(s):  
Molecular Weight ◽  
Dimensional Stability ◽  
Phenol Formaldehyde ◽  
Treated Wood ◽  
Weight Percent Gain ◽  
Weight Percent ◽  
Solid Wood ◽  
Wood Products ◽  
Birch Wood ◽  
Molecular Weights

Abstract This study investigated the effect of phenol-formaldehyde (PF) resin treatment on the dimensional stability of birch solid wood and plywood. Therefore, three different low molecular weight PF resins with average molecular weights (M w ) of 292, 528, and 884 g/mol were synthesized and used for silver birch (Betula pendula) solid wood (20 × 20 × 20 mm3) and veneer (100 × 100 × 1.4 and 300 × 300 × 1.4 mm3) impregnation to produce plywood. The weight percent gain (WPG) and bulking after curing of resin treated wood specimens were determined. The leaching was performed to evaluate the PF resin fixation stability. All tested resins at all concentrations were similarly fixed in wood blocks after the leaching (1.5–2.0% WPG loss). The dimensional stability of birch wood after treatment with all tested PF resins was significantly improved. The anti-swelling efficiency (ASE) of birch wood blocks treated with PF resins after seven water soaking-drying cycles was in the range of 39–53%, 46–65% and 49–65% using 10, 15 and 20% solution concentrations, respectively. Whereas, the ASE of plywood obtained from veneers treated with 10% of PF solution was improved by 6–20%. The equilibrium moisture content (EMC) and volumetric swelling (VS) of PF treated plywood at 98% of relative humidity (RH) decreased significantly. All PF resin treated plywood surfaces were more hydrophobic compared to untreated plywood.

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