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Forests
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Advanced Technologies in Physical and Mechanical Wood Modification
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Advanced Technologies in Physical and Mechanical Wood Modification

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 (30 June 2023) | Viewed by 29113

Special Issue Editors

Dr. Radoslaw Mirski

E-Mail Website
Guest Editor
Faculty of Wood Technology, Poznan University of Life Sciences, Poznan, Poland
Interests: wood sciences
Special Issues, Collections and Topics in MDPI journals
Dr. Dorota Dziurka

E-Mail Website
Guest Editor
Faculty of Forestry and Wood Technology, Department of Wood-Based Materials, Poznań University of Life Sciences, Poznań, Poland
Interests: wood sciences
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Wood is a material with physical and mechanical properties so impressive that it is difficult to substitute it with alternatives. Due to both its physical structure and its chemical composition (cellulose, lignin, hemicellulose, and other components), it is a valuable material in many applications. However, the use of wood also has its limitations. Due to its size and limited resistance to biodegradation (and weathering), it often requires additional technological treatment. Such processes are generally aimed at improving the physical, biological, and in many cases mechanical properties of wood. All reactions occurring in the wood structure, as well as its final properties, are directly related to the type of agents used for such wood treatment. In this area, we can distinguish thermal treatment, mechanical treatment (often used to change the density of the wood but also to change its form), and processes of saturation/impregnation or transformation of wood to another form. These processes result in materials with significantly improved characteristics compared to the wood used. The resulting material is often characterized not only by the improvement of a given feature (assumed in the technological process) but often additionally by other features that further broaden its application.   

The aim of this Special Issue is to update the knowledge on the latest wood modification processes and to present wood-based products with improved or modified properties. This issue is also intended to provide a space for the presentation of not only new technological solutions for wood modification but also to identify features as well as drawbacks of wood that need to be improved.  Therefore, we encourage you to submit both purely scientific articles as well as review papers or even interesting expert opinions on new processes of both shallow and deep wood modification. The papers may also indicate directions for the use of modified wood or wood materials.

Dr. Radoslaw Mirski
Dr. Dorota Dziurka
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Forests is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • wood processing
  • wood properties
  • wood physicochemistry
  • wood compaction
  • wood thermal treatment
  • mechanical processing of wood
  • hydrothermal treatment of wood
  • new wood-based materials with improved characteristics

Published Papers (16 papers)

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Research

10 pages, 2211 KiB  
Article
Water Vapor Sorption Kinetics of Beech Wood Modified with Phenol Formaldehyde Resin Oligomers
by Qian Lang, Vladimirs Biziks and Holger Militz
Forests 2023, 14(10), 2015; https://doi.org/10.3390/f14102015 - 07 Oct 2023
Viewed by 728
Abstract
Beech is an important tree species in Europe. This study aimed to elucidate the influence of four molecular weights of phenol formaldehyde (PF) resin (266, 286, 387, and 410 g/mol) on the sorption behavior of unmodified and modified beech wood samples using a [...] Read more.
Beech is an important tree species in Europe. This study aimed to elucidate the influence of four molecular weights of phenol formaldehyde (PF) resin (266, 286, 387, and 410 g/mol) on the sorption behavior of unmodified and modified beech wood samples using a dynamic vapor sorption (DVS) apparatus. The variations in the environmental relative humidity and moisture content (MC) of the samples were recorded, and the DVS isotherms were plotted from the equipment. During the sorption process, the MC of the modified samples decreased in comparison to that of the unmodified samples, and both apparently decreased with the increasing molecular weight of the PF resin. The DVS isotherm hysteresis plot illustrated a reduction in sorption hysteresis for the modified wood with varying PF resins compared to the unmodified samples. Based on the DVS isotherm adsorption and desorption plots, the decrease in the equilibrium of the MC can be attributed to there being fewer sorption sites in the modified samples, which exhibited the lowest hygroscopicity. Overall, the moisture sorption mechanism for both types of samples was clarified, highlighting a clear correlation between the molecular weight of the applied PF resin and its influence on moisture sorption behavior. Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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17 pages, 4145 KiB  
Article
The Effect of Ethanol Extracts and Essential Oils Obtained from Different Varieties of Mint on Wood Molding
by Izabela Betlej, Bogusław Andres, Krzysztof Krajewski, Anna Kiełtyka-Dadasiewicz, Piotr Boruszewski, Dominika Szadkowska, Janusz Zawadzki, Andrzej Radomski and Piotr Borysiuk
Forests 2023, 14(8), 1522; https://doi.org/10.3390/f14081522 - 26 Jul 2023
Cited by 1 | Viewed by 928
Abstract
This paper presents the results of research on the effect of essential oils and ethanol extracts on the growth of mold fungi on Scots pine (Pinus sylvestris L.) wood. The analysis of fungal growth on the microbial medium showed that the degree [...] Read more.
This paper presents the results of research on the effect of essential oils and ethanol extracts on the growth of mold fungi on Scots pine (Pinus sylvestris L.) wood. The analysis of fungal growth on the microbial medium showed that the degree of inhibition of microorganism growth depends on the amount of the extract added to the medium. At the same time, it was found that the highest dose of the extract, amounting to 5.0 cm3, almost completely inhibited the growth of fungi. In addition, it was found that mint ethanol extracts, the application of which in the wood is at least 40 g/m2, have a fungistatic effect at the initial stage of fungal development. Solutions of essential oils turned out to be more active against fungi, although also in this case the desired biocidal effect was not achieved. Essential oils significantly slowed down the growth of the fungus Ch. globosum, with the strongest fungistatic effect found for ‘Morocco’ spearmint oil (Mentha spicata L.). Despite the fact that in tests on agar-maltose medium, the strongest biocidal activity against Ch. globosum was found for spearmint ‘Crispa’ (Mentha spicata L.) oil, the effect of growth inhibition was not so clearly visible in studies on wood. Essential oils applied to the surface of the wood slowed down the growth of T. viride fungus, but not to the extent that it was found in the case of Ch. globosum. The qualitative and quantitative composition of substances belonging to the group of terpenes and their derivatives was characterized using the GCMS technique. It was shown that the ethanol extracts of mints were dominated by substances belonging to the oxygen-containing monoterpenoid and monoterpene groups. In terms of quality, the composition of essential oils turned out to be richer. Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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11 pages, 5740 KiB  
Article
The Influence of Processing Conditions on the Quality of Bent Solid Wood from European Oak
by Aleš Straže, Jure Žigon, Stjepan Pervan, Mislav Mikšik and Silvana Prekrat
Forests 2023, 14(5), 1047; https://doi.org/10.3390/f14051047 - 18 May 2023
Cited by 1 | Viewed by 1146
Abstract
Bending of solid wood from European oak is one of the most demanding technological processes due to its specific structural and physical properties and variability. We investigated the influence of wood moisture content (MC) and stiffness, determined by NDT, as well as previous [...] Read more.
Bending of solid wood from European oak is one of the most demanding technological processes due to its specific structural and physical properties and variability. We investigated the influence of wood moisture content (MC) and stiffness, determined by NDT, as well as previous drying methods on the bending ability of the wood. The best quality was obtained with bending specimens bent at a moisture content of at least 16% and quarter- or semi-quartersawn. The number of rejected specimens increased slightly when HF bending was used. Single-stage predrying of oak to a final MC of 8% resulted in a high rejection rate (>70%) regardless of drying technique. The acceptance rate was higher for less stiff specimens where the ratio of ultrasonic velocity in the straight (vS) and bent region (vB) was less than 0.5 (vB/vS). Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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13 pages, 2672 KiB  
Article
Molecular Dynamics Study on Mechanical Properties of Cellulose with Water Molecules Diffusion Behavior at Different Oxygen Concentrations
by Yuanyuan Guo, Wei Wang and Xuewei Jiang
Forests 2023, 14(2), 371; https://doi.org/10.3390/f14020371 - 12 Feb 2023
Cited by 3 | Viewed by 1323
Abstract
Six groups of cellulose-water-oxygen simulation models with oxygen concentrations of 0%, 2%, 4%, 6%, 8%, and 10% were established by molecular dynamics software to analyze the effect of oxygen concentration on the mechanical properties of wood cellulose during water vapor heat treatment in [...] Read more.
Six groups of cellulose-water-oxygen simulation models with oxygen concentrations of 0%, 2%, 4%, 6%, 8%, and 10% were established by molecular dynamics software to analyze the effect of oxygen concentration on the mechanical properties of wood cellulose during water vapor heat treatment in terms of the number of hydrogen bonds, the diffusion coefficient of water molecules, the mean square displacement of cellulose chains, and mechanical parameters. The results showed that the diffusion coefficient of water molecules increased steadily as oxygen concentration increased, which affected cell size and density to some extent. The mean square displacement of the cellulose chain at a higher oxygen concentration was larger than at a lower oxygen concentration, indicating that the cellulose chain became more unstable at high oxygen concentration. This trend was consistent with the amount of hydrogen bonds inside the cellulose chains. The analysis of mechanical parameters showed that Young’s modulus and shear modulus showed a trend of increasing and then decreasing with increasing oxygen concentration, and wood cellulose had good resistance to deformation and rigidity at 2% oxygen concentration. Therefore, during the heat treatment of wood, appropriately increasing the oxygen concentration will potentially improve the rigidity and distortion resistance of wood. Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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6 pages, 12227 KiB  
Communication
The Effect of the Tree Dieback Process on the Mechanical Properties of Pine (Pinus sylvestris L.) Wood
by Zbigniew Malinowski, Jakub Kawalerczyk, Joanna Walkiewicz, Dorota Dziurka and Radosław Mirski
Forests 2023, 14(2), 274; https://doi.org/10.3390/f14020274 - 31 Jan 2023
Cited by 1 | Viewed by 1059
Abstract
As a result of the progressing climate changes, there is an increase in the volume of pine deadwood harvested each year from Polish forests. Its presence is an important part of the forest ecosystem; however, there are some indications that the material obtained [...] Read more.
As a result of the progressing climate changes, there is an increase in the volume of pine deadwood harvested each year from Polish forests. Its presence is an important part of the forest ecosystem; however, there are some indications that the material obtained from dying trees can be characterized by lower quality and properties. Taking into account the growing issue of tree dieback, the volume of pine wood annually harvested in Poland, and the importance of wooden products from an economic standpoint, preliminary research aimed at recognizing the process and its effect on the mechanical properties was conducted. Model trees in Brzeg Forest District were selected based on the crown defoliation. The properties of wood obtained from trees representing three different categories of soundness were determined according to the relevant standards. Based on the results of density, modulus of elasticity, bending strength, and compressive strength, it was found that there were statistically significant differences in wood quality depending on the condition of the tree. The results were particularly interesting in the case of compressing strength, where a healthy tree of lower density showed a similar strength to a dying tree with a much higher density. Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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12 pages, 3203 KiB  
Article
Influence of Thermo-Mechanical Densification (TMD) on the Properties of Structural Sawn Timber (Pinus sylvestris L.)
by Marek Grześkiewicz, Sławomir Krzosek, Izabela Burawska, Piotr Borysiuk and Piotr Mańkowski
Forests 2023, 14(2), 231; https://doi.org/10.3390/f14020231 - 26 Jan 2023
Viewed by 985
Abstract
The article presents the results of thermo-mechanical densification tests conducted on Scots pine timber. The densification process was carried out in industrial conditions with a high-pressure press, which allowed flat compression of boards that were up to 2.5 m long. A phenomenon of [...] Read more.
The article presents the results of thermo-mechanical densification tests conducted on Scots pine timber. The densification process was carried out in industrial conditions with a high-pressure press, which allowed flat compression of boards that were up to 2.5 m long. A phenomenon of elastic redeformations was observed in the densified boards after each pulse of compression. As a result of thermo-mechanical compression, the average timber moisture content dropped to 9%, and the average density increased by 13.5%, from the level of 547 to 621 kg/m3. As a result of thermo-mechanical densification, the strength class C of most Scots pine timber pieces improved. Most timber pieces that were subjected to thermo-mechanical densification have improved their strength class, C, by one (72.7% of the tested batch) or two C classes (3.6% of the batch under study). Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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14 pages, 8564 KiB  
Article
Influence of Upcycled Post-Treatment Bark Biomass Addition to the Binder on Produced Plywood Properties
by Aleksandra Jeżo, Anita Wronka, Aleksander Dębiński, Lubos Kristak, Roman Reh, Janis Rizhikovs and Grzegorz Kowaluk
Forests 2023, 14(1), 110; https://doi.org/10.3390/f14010110 - 06 Jan 2023
Cited by 5 | Viewed by 2918
Abstract
The valorization of tree bark through chemical treatment into valuable products, such as bark acid, leads to the formation of process residues with a high solids content. Since they are of natural origin and are able to be suspended in water and acid, [...] Read more.
The valorization of tree bark through chemical treatment into valuable products, such as bark acid, leads to the formation of process residues with a high solids content. Since they are of natural origin and are able to be suspended in water and acid, research was carried out on the recycling of suberic acid residues (SAR) as a bi-functional component of binder mixtures in the production of plywood. The 5%–20% (5%–30% for curing time) mass content of SAR has been investigated with urea-formaldehyde (UF) resin of about 66% of dry content. The results show that the curing time of the bonding mixture can be reduced to about 38% and 10%, respectively, for hot and cold curing, of the initial curing time for the lowest SAR content. The decreasing curing time of the tested binder mixtures with the increase in SAR content was caused by the increasing amount of acidic filler, since amine resins as UF require acidification hardening, and the curing dynamics are strongly dependent, among others, on the content of the acid medium (curing agent). In the case of hot curing, a SAR content of about 20% allowed us to achieve the curing time of bonding mass with an industrial hardener. Investigations into the mechanical properties of examined panels showed a significant modulus of elasticity (MOE) increase with filler content increase. Similar conclusions can be drawn when analyzing the results of the modulus of rupture (MOR) investigations; however, these were only significant regarding hot-pressed samples. The shear strength of the plywood samples increased with the SAR rise for both cold- and hot-pressed panels. The in-wood damage of samples with SAR filler, hot-pressed, rose up to about 30% for the highest SAR filler content. For cold-pressed samples, no in-wood damage was found. The positive effect of veneer impregnation limiter by resin was identified for SAR acting as a filler. Moreover, a higher density of SAR-containing bonding lines was reached for hot-pressed panels. Therefore, the results confirmed the ability to use the SAR as an upcycled component of the bonding mixture for plywood production. Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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16 pages, 9273 KiB  
Article
Physical and Mechanical Properties of High-Density Fiberboard Bonded with Bio-Based Adhesives
by Aneta Gumowska and Grzegorz Kowaluk
Forests 2023, 14(1), 84; https://doi.org/10.3390/f14010084 - 02 Jan 2023
Cited by 12 | Viewed by 6498
Abstract
The high demand for wood-based composites generates a greater use of wood adhesives. The current industrial challenge is to develop modified synthetic adhesives to remove harmful formaldehyde, and to test natural adhesives. The scope of the current research included the manufacturing of high-density [...] Read more.
The high demand for wood-based composites generates a greater use of wood adhesives. The current industrial challenge is to develop modified synthetic adhesives to remove harmful formaldehyde, and to test natural adhesives. The scope of the current research included the manufacturing of high-density fiberboards (HDF) using natural binders such as polylactic acid (PLA), polycaprolactone (PCL), and thermoplastic starch (TPS) with different resination (12%, 15%, 20%). The HDF with biopolymers was compared to a reference HDF, manufactured following the example of industrial technology, with commonly used adhesives such as urea-formaldehyde (UF) resin. Different mechanical and physical properties were determined, namely modulus of rupture (MOR), modulus of elasticity (MOE), internal bonding strength (IB), thickness swelling (TS), water absorption (WA), surface water absorption (SWA), contact angle, as well as density profile; scanning electron microscope (SEM) analysis was also performed. The results showed that increasing the binder content significantly improved the mechanical properties of the panels in the case of starch binder (MOR from 31.35 N mm−2 to 40.10 N mm−2, IB from 0.24 N mm−2 to 0.39 N mm−2 for dry starch), and reduces these in the case of PLA and PCL. The wet method of starch addition improved the mechanical properties of panels; however, it negatively influenced the reaction of the panels to water (WA 90.3% for dry starch and 105.9% for wet starch after 24 h soaking). Due to dynamically evaporating solvents from the PLA and PCL binding mixtures, a development of the fibers’ resination (blending) techniques should be performed, to avoid the uneven spreading of the binder over the resinated material. Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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8 pages, 2048 KiB  
Article
Impact of Sugar Beet Pulp Share on Selected Physical and Mechanical Properties of Particleboards
by Radosław Auriga, Piotr Borysiuk, Maciej Latos, Alicja Auriga, Łukasz Kwaśny and Joanna Walkiewicz
Forests 2023, 14(1), 40; https://doi.org/10.3390/f14010040 - 26 Dec 2022
Viewed by 1049
Abstract
The aim of this study was to investigate the applicability of sugar beet pulp (SBP) in particleboard production as a substitute for wood material. Two variants of board density, 650 kg/m3 and 550 kg/m3, containing 0%, 25% and 50% of [...] Read more.
The aim of this study was to investigate the applicability of sugar beet pulp (SBP) in particleboard production as a substitute for wood material. Two variants of board density, 650 kg/m3 and 550 kg/m3, containing 0%, 25% and 50% of SPB, were evaluated. During the study the following features were measured: modulus of rupture (MOR), modulus of elasticity (MOE), thickness swelling (TS) and water absorption (WA). The results showed that boards containing up to 25% of SBP meet standards for boards for general-purpose used in dry conditions. Further increases in SBP content deteriorated some of the investigated properties of the boards. Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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11 pages, 3443 KiB  
Article
Influence of Phenol–Formaldehyde Resin Oligomer Molecular Weight on the Strength Properties of Beech Wood
by Qian Lang, Vladimirs Biziks and Holger Militz
Forests 2022, 13(12), 1980; https://doi.org/10.3390/f13121980 - 23 Nov 2022
Cited by 2 | Viewed by 1315
Abstract
The objective of this study was to determine the effects of four phenol–formaldehyde (PF) resin treatments with different molecular weights at four different concentrations (5, 10, 15, and 20%) in treated beech wood. The mechanical properties of untreated and treated beech wood were [...] Read more.
The objective of this study was to determine the effects of four phenol–formaldehyde (PF) resin treatments with different molecular weights at four different concentrations (5, 10, 15, and 20%) in treated beech wood. The mechanical properties of untreated and treated beech wood were evaluated. After impregnation with PF resin, all modified beech wood at all PF resin concentrations exhibited an increase in weight percent gain compared with that in untreated beech samples. PF resins with lower molecular weights more easily penetrate the wood cell wall, leading to increased bulking of the wood structure, which in turn improves the dimensional stability of the wood. The PF resin treatment with a molecular weight of 305 g/mol showed better impregnation ability than that of the other PF resins. The impact bending strength of PF-treated wood was considerably reduced because PF-cured resins formed inside the wood and are rigid and brittle. Additionally, PF resin treatments at all concentrations decreased the modulus of elasticity of the wood. Scanning electron microscopy and light microscopy revealed that the PF resins were comparatively well fixed in the wood samples. The results indicate that the large molecular weight PF resins are more uniformly distributed in the fiber lumens. Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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10 pages, 2777 KiB  
Article
A Study on the Susceptibility of PLA Biocomposites to Drilling
by Piotr Borysiuk, Radosław Auriga, Jacek Wilkowski, Alicja Auriga, Adrian Trociński and Lee Seng Hua
Forests 2022, 13(11), 1950; https://doi.org/10.3390/f13111950 - 18 Nov 2022
Cited by 3 | Viewed by 1145
Abstract
Wood–plastic composites (WPCs) increase the range of applications of materials by creating new material solutions. As part of this research, PLA (polylactic acid)- and HDPE (high-density polyethylene)-based composites were manufactured. Softwood sawdust or conifer bark with different sizes (large and small) were used [...] Read more.
Wood–plastic composites (WPCs) increase the range of applications of materials by creating new material solutions. As part of this research, PLA (polylactic acid)- and HDPE (high-density polyethylene)-based composites were manufactured. Softwood sawdust or conifer bark with different sizes (large and small) were used as filler. In selected cases, the addition of 3% additives, such as calcium oxide in the case of PLA or polyethylene-graft-maleic anhydride in the case of HDPE, were tested. The manufactured composites were examined for their density profile and their susceptibility to drilling, defined by the value of the axial force occurring during drilling. The obtained results revealed that the type of matrix had the greatest influence on the axial forces during drilling. Regardless of the composite formulation, composites based on PLA had 25% to 56% higher axial forces during drilling than those based on HDPE. Furthermore, increasing the proportion of lignocellulosic fillers resulted in a decrease in the value of axial forces during drilling, with PLA composites experiencing a greater decrease than HDPE composites. The type and size of the filler had a minor impact on the axial force values during drilling. The statistical analysis indicated that the additives had a greater influence on HDPE than on PLA. Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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12 pages, 4333 KiB  
Article
The Impact of Vinylotrimethoxysilane-Modified Linseed Oil on Selected Properties of Impregnated Wood
by Waldemar Perdoch, Ewelina Depczyńska, Karolina Tomkowiak, Monika Furgał, Mariola Kurczak and Bartłomiej Mazela
Forests 2022, 13(8), 1265; https://doi.org/10.3390/f13081265 - 10 Aug 2022
Cited by 2 | Viewed by 1549
Abstract
This study aimed to examine the effect of organosilicon compounds-modified linseed oil parameters on wood utility properties. Linseed oil silylation with an organosilicon compound containing a vinyl group (vinyltrimethoxysilane) has made it possible to synthesize products characterized by high stability in storage. The [...] Read more.
This study aimed to examine the effect of organosilicon compounds-modified linseed oil parameters on wood utility properties. Linseed oil silylation with an organosilicon compound containing a vinyl group (vinyltrimethoxysilane) has made it possible to synthesize products characterized by high stability in storage. The impregnation of wood with these resulting products contributed to increased resistance of the protected wood to water exposure when compared to unprotected wood or wood protected by polymerized oil that was not subject to the silylation reaction. The protected wood was characterized by a lower water absorption rate in liquid as well as vapor forms contained in the humid air. This property immediately translated into an increase in the resistance of the wood exposed to Basidiomycota. The loss of mass of Pinus sylvestris L. (pine wood) exposed to the Coniophora puteana was approximately 3%. This parameter did not improve when the wood was subjected to the washing process (mass loss approx. 3.6%). Thus, the resulting products are those demonstrating the highest potential for use in the preparation of wood protection means. Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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17 pages, 7796 KiB  
Article
Experimental Study on Tenon and Mortise Joints of Wood-Structure Houses Reinforced by Innovative Metal Dampers
by Shibin Yu, Wen Pan, Hexian Su, Liaoyuan Ye and Daohang Wang
Forests 2022, 13(8), 1177; https://doi.org/10.3390/f13081177 - 25 Jul 2022
Cited by 4 | Viewed by 1782
Abstract
To improve the seismic performance of Chinese traditional wood-structure houses, this paper proposes to strengthen their mortise and tenon joints by applying an innovative metal damper. According to the dimensions of the “Yikeyin” wood-structure houses in the Tonghai area of Yunnan Province, two [...] Read more.
To improve the seismic performance of Chinese traditional wood-structure houses, this paper proposes to strengthen their mortise and tenon joints by applying an innovative metal damper. According to the dimensions of the “Yikeyin” wood-structure houses in the Tonghai area of Yunnan Province, two groups of six samples of three types of mortise and tenon joints were manufactured, in which one group was mounted with dampers made of Q235 steels. Subsequently, a low-cycle repeated loading test was conducted to examine the overall behavior of these joints. Various characteristics of seismic performance indexes, such as the moment–rotation hysteresis curve, skeleton curve, stiffness degradation, energy dissipation capacity, residual amount of tenon and the removal before and after reinforcements of straight, penetrated and dovetail tenon joints were analyzed. The test results show that these tenons exhibit good deformation capacity, their hysteresis curves became fuller and their “pinch” effects were significantly reduced, all after their joints became strengthened, indicating that their joint slips were reduced during the loading processes and their residual amounts of tenon removals were under effective control. Compared with the blank group, the joint stiffness was substantially improved, and the increase in the reverse stiffness turned greater than that of the positive stiffness at each stage of loading, while the degradation curve of the whole joint stiffness became steeper. After mounting the dampers, the bearing capacity and energy dissipation of the joints were significantly improved, the equivalent viscous damping coefficients of the straight and penetrated tenon joints were increased, but that of the dovetail joint was slightly reduced. These study results can provide a reference for the reinforcement and protection of traditional wood-structure houses. Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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14 pages, 2898 KiB  
Article
Effect of Impregnation with a Low-Concentration Furfuryl Alcohol Aqueous Solution on Hygroscopic Properties of Chinese Fir and Poplar Wood
by He Sun, Xun Chang, Changqing Fu, Yuntian Yan, Chunlei Dong and Taian Chen
Forests 2022, 13(8), 1176; https://doi.org/10.3390/f13081176 - 25 Jul 2022
Cited by 2 | Viewed by 1498
Abstract
Furfurylation with a low concentration of furfuryl alcohol (FA) promotes the improvement of the properties and the effectiveness of FA on cell–wall action without darkening the furfurylated wood to the point that it affects its applications. In this paper, the effects of furfurylation [...] Read more.
Furfurylation with a low concentration of furfuryl alcohol (FA) promotes the improvement of the properties and the effectiveness of FA on cell–wall action without darkening the furfurylated wood to the point that it affects its applications. In this paper, the effects of furfurylation on the hygroscopicity and water uptake dimensional stability of poplar (Populus sp.) and Chinese fir (Cunninghamia lanceolata) were analyzed. Meanwhile, the distribution of FA resin, the relationship between wood and water, the change in pore size distribution, and the weight percentage gain and cell wall bulking coefficient of wood were also investigated. The results were as follows: (1) A low concentration of FA could better enter the cell walls of the Chinese fir than the poplar, as FA resin was almost cured in the secondary walls, cell corners, and compound middle lamellae when a 10% concentration of FA was applied to the Chinese fir and poplar. When the FA concentration was increased to 30%, there were no significant increases in the amount of FA entering the cell walls and the amounts of FA cured in the cell lumen of the poplar were greater than those of the Chinese fir. Meanwhile, the modification of cell walls was more suitable in poplar than in Chinese fir. (2) The pointed ends of the pit chambers and the pit apertures (800–1000 nm) in the poplar and the small pores of the pit membranes and the pit apertures (1–6 μm) in the Chinese fir were partially deposited by the FA resin, which formed new pores in the size ranges of 80–600 nm and 15–100 nm, respectively. The porosity of the poplar was greater than that of the Chinese fir, and the bulk density of the poplar was less than that of the Chinese fir before and after modification. (3) Furfurylation with a low concentration of FA was able to better reduce the equilibrium moisture content, improve the anti-swelling efficiency, and enhance the dimensional stability of the poplar wood compared to the Chinese fir. Furfurylation effectively reduced water uptake due to the hydrophobic property of the FA resin. The water uptake of the Chinese fir increased by 17%–19% in second cyclic water soaking when treated with FA with various concentrations, which indicated the loss and leaching of FA resin during the test. Low-field NMR was used to demonstrate that the furfurylation not only reduced the amount of water but also affected the combination state of bound and free water with wood. Thus, furfurylation at a low concentration is a feasible method by which to extend applications of furfurylated wood. Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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9 pages, 2087 KiB  
Communication
Timber Properties and Cellulose Crystallites Size in Pine Wood Cut in Different Sawing Patterns after Pretreatment with CH3COOH and H2O2 and Densification
by Andi Detti Yunianti, S Suhasman, A Agussalim, Musrizal Muin and Heru Arisandi
Forests 2021, 12(11), 1607; https://doi.org/10.3390/f12111607 - 22 Nov 2021
Viewed by 1718
Abstract
One process to improve wood quality is densification or wood surface compression. Our study analyzed the changes in some basic properties of pine wood, including its anatomical structure, density, modulus of elasticity (MOE), and dimensions of cellulose crystallites, after densification following soaking pretreatment [...] Read more.
One process to improve wood quality is densification or wood surface compression. Our study analyzed the changes in some basic properties of pine wood, including its anatomical structure, density, modulus of elasticity (MOE), and dimensions of cellulose crystallites, after densification following soaking pretreatment in CH3COOH and H2O2 at a concentration of 20%. Samples were sawn in radial and tangential directions for analysis of the wood. The results showed a change in the shape of tracheid cells from hexagonal to oval, as well as damage to the ray cell constituents on the tangential surface. The thickness decrease of the samples was in accordance with the target, which meant that spring-back was short. In general, the tangential boards had a higher density than the radial boards, with a lower MOE and crystallite dimensions. Our findings showed that the densified tangential board was stronger than the radial board. Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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9 pages, 1925 KiB  
Article
Dimensional Stability of Treated Sengon Wood by Nano-Silica of Betung Bamboo Leaves
by Istie Rahayu, Fitria Cita Dirna, Akhiruddin Maddu, Wayan Darmawan, Dodi Nandika and Esti Prihatini
Forests 2021, 12(11), 1581; https://doi.org/10.3390/f12111581 - 17 Nov 2021
Cited by 2 | Viewed by 1730
Abstract
Sengon (Falcataria moluccana Miq.) is one of the fastest growing wood that is broadly planted in Indonesia. Sengon wood has inferior wood properties, such as a low density and dimensional stability. Therefore, sengon wood requires a method to improve its wood quality [...] Read more.
Sengon (Falcataria moluccana Miq.) is one of the fastest growing wood that is broadly planted in Indonesia. Sengon wood has inferior wood properties, such as a low density and dimensional stability. Therefore, sengon wood requires a method to improve its wood quality through wood modification. One type of wood modification is wood impregnation. On the other hand, Betung Bamboo leaves are considered as waste. Betung Bamboo leaves contain silica. Based on several researches, nano-SiO2 could improve fast-growing wood qualities. According to its perfect solubility in water, monoethylene glycol (MEG) is used in the study. The objectives are to evaluate the impregnation treatment (MEG and nano-silica originated from betung bamboo leaves) in regard to the dimensional stability and density of 5-year-old sengon wood and to characterize the treated sengon wood. MEG, MNano-Silica 0.5%, MNano-Silica 0.75%, and MNano-Silica 1% were used as impregnation solutions. The impregnation method was started with 0.5 bar of vacuum for 60 min, followed by 2.5 bar of pressure for 120 min. The dimensional stability, density, and characterization of the samples were studied through the use of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results show that the treatment had a significant effect on the dimensional stability and density of sengon wood. Alterations in the morphology of treated sengon wood were observed through the full coverage of the pits on the vessel walls (SEM analysis results) and the detection of ethylene (FTIR analysis results) and silica (XRD and FTIR analysis results). Overall, the 0.75% MNano-Silica treatment was the most optimal treatment for increasing the dimensional stability and density of 5-year-old sengon wood. Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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