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Forests
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Performance and Modification of Wood and Wood-Based Materials
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Performance and Modification of Wood and Wood-Based Materials

A special issue of Forests (ISSN 1999-4907). This special issue belongs to the section "Wood Science and Forest Products".

Deadline for manuscript submissions: closed (25 November 2022) | Viewed by 51484

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Dr. Tomasz Krystofiak

E-Mail Website
Guest Editor
Laboratory of Gluing and Finishing of Surface, Department of Wood Science and Thermal Techniques, Poznan University of Life Sciences, Wojska Polskiego 38/42 St., 60-627 Poznan, Poland
Interests: wood; wood-based composite; adhesive; lacquer product; coating; substrate; wettability; strength; adhesion
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Pavlo Bekhta

E-Mail Website
Guest Editor
Department of Wood-Based Composites, Cellulose and Paper, Ukrainian National Forestry University, 79057 Lviv, Ukraine
Interests: wood science and technology; wood–polymer composites; lignocellulosic based composites; wood modification; wood bonding
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Wood remains one of the most attractive construction materials. However, its applications are limited because it undergoes biological degradation, is combustible, and changes its properties under the influence of weathering conditions. Many of these disadvantages of solid wood are to some extent eliminated in wood-based materials such as plywood, particleboard, fiberboard, OSB, etc. However, in addition to the fact that it is not possible to completely eliminate the shortcomings of solid wood, these materials are bring new shortcomings, such as toxicity. Therefore, the problem of improving the properties of wood and wood-based materials is still in need of solutions. One of the effective ways to improve the properties of wood and wood-based materials is to modify them by conventional (thermal, chemical etc.) or the latest (plasma treatment) processes. With regard to wood-based materials, it is possible to treat their components (particles, fibers, glue, etc.) and the use them in wood-based materials or to use the post-treatment of ready-made materials to improve their certain properties.

Emphasis in this Special Issue is placed on updating and expanding the knowledge concerning conventional and novel modification processes of wood and wood-based materials, their improved/modified properties, and their relevant applications. 

Dr. Tomasz Krystofiak
Prof. Dr. Pavlo Bekhta
Guest Editors

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Keywords

  • wood modification processes
  • chemical treatment of wood
  • hydrothermal treatment of wood
  • thermo-hydro and thermo-hydro-mechanical treatment of wood
  • thermal and thermo-mechanical treatment of wood
  • acetylation of wood
  • surface densification
  • surface treatment of wood and wood-based materials
  • plasma surface treatment
  • properties of modified wood
  • properties of modified wood-based materials
  • wettability of wood and wood-based materials and their treated surfaces
  • surface properties of wood and wood-based materials
  • aesthetic properties of wood and wood-based materials
  • fire-retardant additives
  • water-repellent additives

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Published Papers (13 papers)

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Editorial

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4 pages, 662 KiB  
Editorial
Performance and Modification of Wood and Wood-Based Materials
by Pavlo Bekhta and Tomasz Krystofiak
Forests 2023, 14(5), 963; https://doi.org/10.3390/f14050963 - 7 May 2023
Cited by 5 | Viewed by 1534
Abstract
Wood remains one of the most attractive building materials [...] Full article
(This article belongs to the Special Issue Performance and Modification of Wood and Wood-Based Materials)

Research

Jump to: Editorial

18 pages, 3482 KiB  
Article
Influence of Chrysoporthe deuterocubensis Canker Disease on the Chemical Properties and Durability of Eucalyptus urograndis against Wood Rotting Fungi and Termite Infestation
by Rasdianah Dahali, Seng Hua Lee, Paridah Md Tahir, Sabiha Salim, Muhammad Syahmi Hishamuddin, Atikah Che Ismail, Pui San Khoo, Tomasz Krystofiak and Petar Antov
Forests 2023, 14(2), 350; https://doi.org/10.3390/f14020350 - 9 Feb 2023
Cited by 3 | Viewed by 1966
Abstract
In this study, the effects of stem canker disease caused by Chrysoporthe deuterocubensis on the chemical properties and durability of a Eucalyptus hybrid (E. urophylla x E. grandis) were investigated. Eleven-year-old healthy and infected trees were collected. The samples were grouped [...] Read more.
In this study, the effects of stem canker disease caused by Chrysoporthe deuterocubensis on the chemical properties and durability of a Eucalyptus hybrid (E. urophylla x E. grandis) were investigated. Eleven-year-old healthy and infected trees were collected. The samples were grouped into four different classes based on the infection severity: healthy (class 1), moderately infected (class 2), severely infected (class 3), and very severely infected (class 4). The changes in chemical properties were evaluated via chemical analysis and Fourier transform infrared spectroscopy (FTIR) analysis. A resistance test against fungal decay (Pcynoporus sanguineus and Caniophora puteana) and termite (Coptotermes curvignathus) was also performed. The results showed that reductions in cellulose and hemicellulose content from 53.2% to 45.4% and 14.1% to 13.9%, respectively, were observed in the infected samples. Meanwhile, the percentages of lignin and extractives increased from 18.1% to 20.5% and 14.6% to 20.2%, respectively. The resistance against fungi and termites varied between severity classes. Generally, infected wood behaved better than healthy wood in terms of durability against fungi and termites. The durability classes for both tests were significantly improved, from resistant to highly resistant and poor to moderately resistant, respectively. These results suggest that E. urograndis that is infected by C. deuterocubensis might have a better potential use in lumber production with regard to its durability and processing cost compared to pulp and paper products. Full article
(This article belongs to the Special Issue Performance and Modification of Wood and Wood-Based Materials)
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18 pages, 4413 KiB  
Article
Properties of Plywood Panels Composed of Thermally Densified and Non-Densified Alder and Birch Veneers
by Pavlo Bekhta, Tomáš Pipíška, Vladimír Gryc, Ján Sedliačik, Pavel Král, Jozef Ráheľ and Jan Vaněrek
Forests 2023, 14(1), 96; https://doi.org/10.3390/f14010096 - 4 Jan 2023
Cited by 9 | Viewed by 1978
Abstract
Ukrainian companies mainly use birch in the manufacture of plywood, but species, such as black alder, are not yet widely used in the manufacture of plywood due to their poorer properties. It is well known that thermal compression is often used to improve [...] Read more.
Ukrainian companies mainly use birch in the manufacture of plywood, but species, such as black alder, are not yet widely used in the manufacture of plywood due to their poorer properties. It is well known that thermal compression is often used to improve the properties of solid wood. Good lay-up schemes of veneer can maximize the advantages and minimize the disadvantages of these wood species, and generally improve the utility value of the plywood. This research aimed to develop plywood panels with two wood species and two types of veneer treatments in order to evaluate the influences of different lay-up schemes on the properties of the plywood. Five-layer plywood panels were formed with 16 different lay-up schemes using birch (Betula verrucosa Ehrh.) (B) and black alder (Alnus glutinosa L.) (A) veneers, which were non-densified (N) and thermally densified (D). The different lay-up schemes were used to identify opportunities to improve the mechanical and physical properties of the plywood by replacing the birch veneer in the plywood structure with an alternative alder veneer. The veneer sheets were thermally densified in a laboratory hot press at a temperature of 180 °C and pressure of 2 MPa for 3 min. The conducted study showed that the bending strength, modulus of elasticity and shear strength of mixed-species plywood (BD–AN–AN–AN–BD) increased by up to 31.5%, 34.4% and 16.8%, respectively, in comparison to those properties of alder plywood from non-densified veneer (AN–AN–AN–AN–AN), by positioning alder non-densified veneers in the core layers and birch densified veneers in the outer layers. Moreover, the surface roughness of plywood panels with outer layers of birch veneer was lower than that of panels with outer layers of alder veneer. It was shown that non-treated alder veneer, despite exhibiting somewhat lower strength properties than birch veneer, could be successfully used with proper lay-up schemes in the veneer-based products industry. Full article
(This article belongs to the Special Issue Performance and Modification of Wood and Wood-Based Materials)
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13 pages, 2462 KiB  
Article
Colour and Chemical Changes of Black Locust Wood during Heat Treatment
by František Kačík, Ivan Kubovský, Jiří Bouček, Richard Hrčka, Milan Gaff and Danica Kačíková
Forests 2023, 14(1), 73; https://doi.org/10.3390/f14010073 - 30 Dec 2022
Cited by 13 | Viewed by 2571
Abstract
Black locust is a fast-growing deciduous tree species with multiple industrial purposes due to its valuable traits. However, the heterogeneity of colour distribution between sapwood and heartwood limits its application. Thermal modification is an environment-friendly technology for improving various wood properties, especially dimensional [...] Read more.
Black locust is a fast-growing deciduous tree species with multiple industrial purposes due to its valuable traits. However, the heterogeneity of colour distribution between sapwood and heartwood limits its application. Thermal modification is an environment-friendly technology for improving various wood properties, especially dimensional stability, decay resistance, and colour homogeneity. In this work, black locust (Robinia pseudoacacia L.) wood samples were thermally modified at temperatures of 160, 180, and 210 °C. Extractives and main wood components were analysed by wet chemical methods, colour was measured by spectrometry, and structural changes by Fourier transform infrared spectroscopy. The obtained results show that the darkening of black locust wood, unlike other wood species of the temperate zone, is mainly caused by changes in extractives. Their content decreases during thermal treatment, but new chromophores are formed, especially in quinones. Degradation of hemicelluloses and the partial degradation of cellulose also contribute to colour changes. At higher temperatures, condensation reactions can occur in lignin, leading to the formation of some chromophores. Statistical analysis confirmed that temperature can be considered a very significant factor affecting the colour of the wood surface. Full article
(This article belongs to the Special Issue Performance and Modification of Wood and Wood-Based Materials)
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21 pages, 4499 KiB  
Article
Multi-Objective Optimization and Analysis of Mechanical Properties of Coir Fiber from Coconut Forest Waste
by Shaofeng Ru, Can Zhao and Songmei Yang
Forests 2022, 13(12), 2033; https://doi.org/10.3390/f13122033 - 30 Nov 2022
Cited by 13 | Viewed by 2730
Abstract
As a type of natural fiber with excellent elongation, coir fiber has been applied in a wide range of fields. To ensure superb performance, coir fiber is usually treated with alkali before being applied. Previous studies paid little attention to the multiple alkali [...] Read more.
As a type of natural fiber with excellent elongation, coir fiber has been applied in a wide range of fields. To ensure superb performance, coir fiber is usually treated with alkali before being applied. Previous studies paid little attention to the multiple alkali treatment of coir fiber; however, this study focuses on its influence on the mechanical properties of coir fiber and conducts multi-objective optimization and analysis of the tensile strength, elastic modulus and elongation of coir fiber. Our objective is the comprehensive enhancement of the mechanical properties of coir fiber. In this study, the experimental design is based on the Box-Behnken design method, and three treatment parameters were selected for the study, namely NaOH concentration, treatment time and treatment temperature. Analysis of variance (ANOVA) was adopted to analyze the experimental data, and response surface methodology (RSM) was used to investigate how the treatment factors interact with each other and affect the responses values. To improve the tensile strength, elastic modulus and elongation of coir fiber simultaneously, the experimental parameters were optimized. The results showed that the optimal values of NaOH concentration, treatment time and treatment temperature were 4.12%, 15.08 h and 34.21 °C, respectively. Under these conditions, the tensile strength of coir fiber was 97.14 MPa, the elastic modulus was 2.98 GPa and the elongation was 29.35%, which were 38.28%, 39.91% and 25.59% higher than that of untreated coir fiber, respectively. Furthermore, scanning electron microscopy (SEM), thermogravimetric analysis (TGA-DTG), Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to analyze the changes in surface, weight loss, composition and crystallinity of coir fiber treated with alkali under optimum conditions compared with untreated coir fiber to obtain a deeper insight into the influential mechanisms of alkali treatment. Full article
(This article belongs to the Special Issue Performance and Modification of Wood and Wood-Based Materials)
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18 pages, 5842 KiB  
Article
Physical and Mechanical Properties Performance between Untreated and Treated with CCA Treatment at Different Age Groups of Fast-Growing Acacia Hybrid of Sarawak
by Gaddafi Ismaili, Ellyne Enduat, Nur Syahina Yahya, Fanthy Moola Malek, Noor Azland Jaimudin, Khairul Khuzaimah Abdul Rahim, Mohd Effendi Wasli, Meekiong Kalu, Iskanda Openg, Ahmad Nurfaidhi Rizalman, Jack Liam and Biha Razali
Forests 2022, 13(12), 1969; https://doi.org/10.3390/f13121969 - 22 Nov 2022
Cited by 2 | Viewed by 2339
Abstract
An effort was carried out to fully utilise fast-growing Acacia hybrid usage in the timber engineering field; however, the research data are still lacking. This paper aims to evaluate the physical and mechanical properties performance between untreated (control) and treated with 10% copper [...] Read more.
An effort was carried out to fully utilise fast-growing Acacia hybrid usage in the timber engineering field; however, the research data are still lacking. This paper aims to evaluate the physical and mechanical properties performance between untreated (control) and treated with 10% copper chrome arsenic of Acacia hybrid collected from Daikin Plantation Sdn. Bhd. Bintulu, Sarawak at air-dry condition at different age groups using the small clear method. Mechanical properties test refers to shear parallel to grain (tangential and radial directions), cleavage (tangential and radial directions), and tension parallel to grain test. Meanwhile, the physical properties test refers to moisture content (MC) and density test. After treatment, mechanical properties increase with an average of 13.67%; meanwhile, moisture content decreased with an average of 0.58% or 0.09% MC, and density slightly increased with an average of 0.44% or 0.002 g/cm3. Results indicate that 10-year-old Acacia hybrid exhibits the highest strength values in shear parallel to the grain, tension parallel to the grain, and cleavage, followed by 13-year-old and 7-year-old. Treated samples in the tangential direction performed better with consistent mean results than that of the untreated samples, while radial direction gave a high average strength increment when treated. Full article
(This article belongs to the Special Issue Performance and Modification of Wood and Wood-Based Materials)
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11 pages, 2183 KiB  
Article
Effect of Thermo-Hydro-Mechanical Treatment on Mechanical Properties of Wood Cellulose: A Molecular Dynamics Simulation
by Feiyu Ouyang and Wei Wang
Forests 2022, 13(6), 903; https://doi.org/10.3390/f13060903 - 9 Jun 2022
Cited by 5 | Viewed by 2145
Abstract
Based on molecular dynamics, a water and cellulose model was constructed to provide more theoretical support for the behavior characteristics of cellulose properties in thermo-hydro-mechanical treatment. In this paper, dynamic simulations were carried out under the NPT ensemble at 4, 5.5, 8, and [...] Read more.
Based on molecular dynamics, a water and cellulose model was constructed to provide more theoretical support for the behavior characteristics of cellulose properties in thermo-hydro-mechanical treatment. In this paper, dynamic simulations were carried out under the NPT ensemble at 4, 5.5, 8, and 12 MPa, respectively. Moreover, we analyze the effects on the mechanical properties of wood cellulose in terms of the hydrogen bond numbers, small molecule diffusion coefficients, end-to-end distances, and mechanical parameters of the water–cellulose model. The results indicate that the densification of the water–cellulose model gradually increases with increasing pressure. The effect of pressures on mechanical properties is mainly due to the formation of massive hydrogen bonds within the cellulose chain and between water and cellulose. This is reflected in the fact that water molecules are more difficult to diffuse in the cellulose, which therefore weakens the negative effect of large amounts of water on the cellulose. The increase in end-to-end distance represents the stiffness of the cellulose chains being strengthened. The mechanical parameters indicate an increase in wood stiffness to resist deformation better, while reducing tensile properties at the same time. The dynamic simulation results in this paper can well correspond to macroscopic experiments. Full article
(This article belongs to the Special Issue Performance and Modification of Wood and Wood-Based Materials)
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21 pages, 5073 KiB  
Article
Evaluation of the Effect of a Combined Chemical and Thermal Modification of Wood though the Use of Bicine and Tricine
by Dennis Jones, Davor Kržišnik, Miha Hočevar, Andreja Zagar, Miha Humar, Carmen-Mihaela Popescu, Maria-Cristina Popescu, Christian Brischke, Lina Nunes, Simon F. Curling, Graham Ormondroyd and Dick Sandberg
Forests 2022, 13(6), 834; https://doi.org/10.3390/f13060834 - 27 May 2022
Cited by 7 | Viewed by 2298
Abstract
The effects of thermal modification of wood have been well established, particularly in terms of reductions in mechanical performance. In recent years, there has been an increase in studies related to the Maillard reaction. More commonly associated with food chemistry, it involves the [...] Read more.
The effects of thermal modification of wood have been well established, particularly in terms of reductions in mechanical performance. In recent years, there has been an increase in studies related to the Maillard reaction. More commonly associated with food chemistry, it involves the reaction of amines and reducing sugars during cooking procedures. This study has attempted to combine the use of amines and thermal modification, with subsequent properties investigated for the treatment of spruce (Picea abies (L.) H. Karst) and beech (Fagus sylvatica L.). In this initial study, the combined effects of chemical treatments by tricine and bicine were investigated with thermal modification. Along with some preliminary data on mechanical properties, the modifications which appeared in the wood structure were evaluated by infrared spectroscopy and biological studies according to EN113 and EN117 methodologies. The hierarchal study interpretation of FTIR suggested interactions between the bicine or tricine and the wood, which was partly supported by the analysis of volatile organic compounds (VOC), though other tests were not as conclusive. The potential of the method warrants further consideration, which will be described. Full article
(This article belongs to the Special Issue Performance and Modification of Wood and Wood-Based Materials)
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12 pages, 2187 KiB  
Article
Creep Properties of Densified Wood in Bending
by Lei Han, Andreja Kutnar, José Couceiro and Dick Sandberg
Forests 2022, 13(5), 757; https://doi.org/10.3390/f13050757 - 14 May 2022
Cited by 4 | Viewed by 2935
Abstract
Thermo-hydro-mechanical (THM)-densified timber is rarely used in construction, although its mechanical properties are in many cases excellent. The main reason for its rare use is set-recovery, which reduces the degree of densification over time so that the mechanical properties deteriorate. Our knowledge of [...] Read more.
Thermo-hydro-mechanical (THM)-densified timber is rarely used in construction, although its mechanical properties are in many cases excellent. The main reason for its rare use is set-recovery, which reduces the degree of densification over time so that the mechanical properties deteriorate. Our knowledge of the long-term creep of densified timber is insufficient and a full understanding of its long-term behaviour is still lacking. The purpose of this study was to examine the behaviour under long-term loading of Scots pine sapwood densified in an open system at 170–200 °C. The influence of the THM densification process on the creep properties was studied on (1) unmodified specimens, (2) THM-densified specimens, (3) THM-densified specimens that had been further thermally treated, and (4) low-molecular-weight phenol-formaldehyde resin-impregnated and THM-densified specimens. All specimens were loaded at 20 ± 2 °C and 65 ± 5% relative humidity for 14 days under 3-point bending at 35% of the short-term ultimate load, and the bending deformation was registered. The THM densification doubled the density, causing a significant increase in the modulus of rupture but no change in the modulus of elasticity, and reduced the equilibrium moisture content and creep compliance. Post-thermal modification and resin impregnation improved the dimensional stability and further reduced the creep compliance in bending. The results demonstrate that THM densification combined with resin-impregnation or thermal modification reduces the creep of Scots pine timber under a long-term bending load in a constant climate. Full article
(This article belongs to the Special Issue Performance and Modification of Wood and Wood-Based Materials)
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10 pages, 3587 KiB  
Communication
Some Properties of Wood Plastic Composites Made from Rubberwood, Recycled Plastic and Silica
by Aujchariya Chotikhun, Jitralada Kittijaruwattana, Wa Ode Muliastuty Arsyad, Emilia-Adela Salca, Yusuf Sudo Hadi and Salim Hiziroglu
Forests 2022, 13(3), 427; https://doi.org/10.3390/f13030427 - 9 Mar 2022
Cited by 10 | Viewed by 3169
Abstract
The objective of this work was to evaluate some of the properties of experimental wood plastic composite (WPC) panels manufactured from a low percentage of rubberwood (Hevea brasiliensis Muell. Arg), waste polyethylene terephthalate (PET) and silica at three different ratios. It was [...] Read more.
The objective of this work was to evaluate some of the properties of experimental wood plastic composite (WPC) panels manufactured from a low percentage of rubberwood (Hevea brasiliensis Muell. Arg), waste polyethylene terephthalate (PET) and silica at three different ratios. It was determined that water absorption values of the samples decreased with the increasing amount of PET in the panels. The lowest absorption value of 0.34% was determined for the samples having 40% PET in their content as a result of 24-h soaking. The highest hardness value of 4492 N was found for the samples made with the combination of rubberwood, PET and silica at 10%, 40% and 50%, respectively. The compressive strength of WPC specimens also followed a similar trend with the hardness characteristics of the panel and improved with increasing PET percentage. Statistical analyses revealed that values of compression strength, hardness, 2-h and 24-h water absorption of the specimens made with 20, 30, and 40% PET content resulted in significant difference from each other (p ≤ 0.0001). Based on the findings in this study it appears that increasing silica content in the samples adversely influenced their mechanical properties while creating a certain level of enhancement of water absorption of the specimens. It seems that using a combination of waste PET and a limited amount of silica with a low percentage of wood particles could have the potential to produce value-added environmentally friendly composites to be used for different applications. Full article
(This article belongs to the Special Issue Performance and Modification of Wood and Wood-Based Materials)
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24 pages, 31257 KiB  
Article
The Impact of Sanding and Thermal Compression of Wood, Varnish Type and Artificial Aging in Indoor Conditions on the Varnished Surface Color
by Pavlo Bekhta, Tomasz Krystofiak, Barbara Lis and Nataliya Bekhta
Forests 2022, 13(2), 300; https://doi.org/10.3390/f13020300 - 12 Feb 2022
Cited by 12 | Viewed by 2682
Abstract
The aim of this pioneering study was to compare and evaluate two different pre-treatment processes of wooden surfaces prior to varnishing by sanding or thermal compression in terms of the impact on the color characteristics of the varnished surface. In the experiment, a [...] Read more.
The aim of this pioneering study was to compare and evaluate two different pre-treatment processes of wooden surfaces prior to varnishing by sanding or thermal compression in terms of the impact on the color characteristics of the varnished surface. In the experiment, a wood veneer of black alder and birch before varnishing was subjected to sanding with a sandpaper of 180 grit size, or thermal compression at temperatures of 180 and 210 °C. Three different kinds of commercially manufactured transparent varnish (water-based (WB) varnish, polyurethane (PUR) varnish and UV-cured (UV) varnish) were applied to the prepared veneer surfaces. The samples prepared in this way were also subjected to an artificial aging process in indoor conditions by ultraviolet light and infrared irradiation (UVL + IR). The colors of the surfaces in the CIE L*a*b* system were measured and color differences (ΔL*, Δa*, Δb* and ΔE) were determined for sanded and thermally densified, unvarnished and varnished, as well as subjected to accelerated aging surfaces. It was found that thermally densified surface-varnished veneer is more resistant to color changes during artificial aging compared to when sanded and surface-varnished. The transparent varnish systems showed better photo-stability, when thermally densified wood veneer was used as substrate than that of sanded wood. The WB varnish showed the greatest resistance to discoloration during UVL + IR irradiation, followed by PUR and UV. The preliminary findings obtained in this study indicated that replacing the sanding process with thermal compression of wood surface before varnishing could be considered as an alternative method of producing varnished panels with satisfactory color properties of surface. Full article
(This article belongs to the Special Issue Performance and Modification of Wood and Wood-Based Materials)
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14 pages, 12469 KiB  
Article
Impregnation of Wood with Waste Engine Oil to Increase Water- and Bio-Resistance
by Larisa Belchinskaya, Konstantin Viktorovich Zhuzhukin, Tatiana Ishchenko and Aleksey Platonov
Forests 2021, 12(12), 1762; https://doi.org/10.3390/f12121762 - 13 Dec 2021
Cited by 14 | Viewed by 21684
Abstract
Impregnation is a common method of protecting wood from external influences. This study proposes the use of spent engine oil as an impregnating composition for modifying birch wood to make it resistant to biological degradation and water. The indicators of water resistance and [...] Read more.
Impregnation is a common method of protecting wood from external influences. This study proposes the use of spent engine oil as an impregnating composition for modifying birch wood to make it resistant to biological degradation and water. The indicators of water resistance and dimensional stability of wood such as wetting contact angle, thermogravimetric analysis, Fourier transform infrared spectroscopy (FTIR), and biodegradation tests have been determined. It has been found that treatment with spent engine oil significantly increases the dimensional stability (56.8% and 45.7% in tangential and radial directions) and water-resistant indicators of wood. Thermogravimetric analysis has showed that the curves for the impregnated specimens were different from the control group and had two sharp peaks at 302 and 357 °C. However, FTIR indicated that no clear chemical reactions occur between spent engine oil and wood. A study on wood resistance to biological degradation has showed a significant increase in resistance against brown rot (Poria placenta fungi) in the treated specimens, in contrast to the control group. Thus, impregnation of wood with spent engine oil makes it possible to increase wood resistance to water and biological degradation. Full article
(This article belongs to the Special Issue Performance and Modification of Wood and Wood-Based Materials)
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11 pages, 2727 KiB  
Article
Water Absorption Properties in Transverse Direction of Heat-Treated Chinese Fir Wood Determined Using TD-NMR
by Yulei Gao, Liyuan Zhao, Jinghui Jiang, Zhu Li and Jianxiong Lyu
Forests 2021, 12(11), 1545; https://doi.org/10.3390/f12111545 - 9 Nov 2021
Cited by 6 | Viewed by 1807
Abstract
Heat treatment is an environmentally friendly method that improves the moisture-resistant properties and increases the service life of timber. In this work, Chinese fir (Cunninghamia lanceolata [Lamb.] Hook.) wood was heat-treated in a chamber with steam at temperatures of 160, 180, 200 [...] Read more.
Heat treatment is an environmentally friendly method that improves the moisture-resistant properties and increases the service life of timber. In this work, Chinese fir (Cunninghamia lanceolata [Lamb.] Hook.) wood was heat-treated in a chamber with steam at temperatures of 160, 180, 200 and 220 °C for 2 h, and the absorption of water was studied by gravimetric analysis and time domain nuclear magnetic resonance (TD-NMR). The results show that both the amount of bound water and free water decreased with the increasing treatment temperature. The water absorption of wood in the radial direction was faster than that in the tangential direction due to the existence of rays, and this difference remained after the heat treatment. The heat treatment at 220 °C had a significant effect on water absorption in the tangential direction of wood, and the moisture content (MC) was approximately 20% lower than that of samples absorbing water in the radial direction. T2 (spin–spin relaxation time) distributions showed two main components which were associated with bound water and free water, and for samples absorbing water in the radial or tangential direction, there was only a difference in the amount of free water. The amount of free water significantly decreased for the samples that were heat-treated at 220 °C and absorbed water in the tangential direction, indicating that the high-temperature heat-treated samples tended to close the pits in wood cells. Full article
(This article belongs to the Special Issue Performance and Modification of Wood and Wood-Based Materials)
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