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Application of Wood Composites
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Application of Wood Composites

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Materials Science and Engineering".

Deadline for manuscript submissions: closed (28 February 2021) | Viewed by 52376

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

Special Issue Editors

Prof. Dr. Roman Réh

E-Mail Website
Guest Editor
Faculty of Wood Sciences and Technology, Technical University in Zvolen, T. G. Masaryka 24, SK-960 01 Zvolen, Slovakia
Interests: wood-based composites; wood adhesives
Special Issues, Collections and Topics in MDPI journals
Dr. Ľuboš Krišťák

E-Mail Website
Guest Editor
Faculty of Wood Sciences and Technology, Technical University in Zvolen, T. G. Masaryka 24, SK-960 01 Zvolen, Slovakia
Interests: physics; materials; thermal properties; wood sciences; wood physics
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Wood composites, that is, any wood material adhesive-bonded together, are the key material for furniture, construction, and the like. Wood composites range from fiberboard to laminated beams. The basic elements for wood composites are fibers and usually larger wood particles and veneers composed of many fibers, varying in size and geometry. Their characteristics and their variations control provide the chief means by which materials are fabricated with predetermined properties. This Special Issue addresses various aspects, including reinforced composite structures, advanced functionalities in laminates, the activation of natural fibers, natural matrix, and other industrial manufacturing research advancements in wood materials as composites.

Prof. Dr. Roman Réh
Prof. Dr. Ľuboš Krišťák
Guest Editors

Manuscript Submission Information

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Keywords

  • wood composites
  • fiberboard
  • particleboard
  • plywood
  • OSB
  • laminated beams
  • reinforced composite structures
  • adhesive mixtures and their components
  • advanced properties
  • application

Published Papers (17 papers)

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Editorial

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3 pages, 211 KiB  
Editorial
Application of Wood Composites
by Ľuboš Krišťák and Roman Réh
Appl. Sci. 2021, 11(8), 3479; https://doi.org/10.3390/app11083479 - 13 Apr 2021
Cited by 12 | Viewed by 1874
Abstract
Wood composites are the key material for a number of structural and non-structural applications for interior and exterior purposes, such as furniture, construction, floorings, windows and doors, etc [...] Full article
(This article belongs to the Special Issue Application of Wood Composites)

Research

Jump to: Editorial, Review

12 pages, 8671 KiB  
Article
Efficiency of Machine Sanding of Wood
by Maciej Sydor, Radosław Mirski, Kinga Stuper-Szablewska and Tomasz Rogoziński
Appl. Sci. 2021, 11(6), 2860; https://doi.org/10.3390/app11062860 - 23 Mar 2021
Cited by 16 | Viewed by 3388
Abstract
We hypothesized that the type of wood, in combination with the grit size of sandpapers, would affect sanding efficiency. Fixed factors were used in the experiment (a belt sander with pressure p = 3828 Pa, and a belt speed of vs = [...] Read more.
We hypothesized that the type of wood, in combination with the grit size of sandpapers, would affect sanding efficiency. Fixed factors were used in the experiment (a belt sander with pressure p = 3828 Pa, and a belt speed of vs = 14.5 m/s) as well as variable factors (three sand belts (P60, P120, P180), six hardwood species (beech, oak, ash, hornbeam, alder, walnut) and three softwood species (pine, spruce, larch)). The masses of the test samples were measured until they were completely sanded. The sanding efficiency of hardwood species is less variable than for softwood species. Maximum sanding efficiency for the softwood ranged from 1 to 2 min, while for the hardwood species, it ranged from 2 to 4.5 min at the start of sanding and then decreased. The average time for complete sanding of the softwood samples was: 87 s (P60), 150 s (P120), and 188 s (P180). For hardwood, these times were 2.4, 1.5, and 1.8 times longer. The results indicate that the factors determining sanding efficiency are the type of wood, and, secondly, the grit size of sanding belts. In the first phase of blunting with the sanding belts, the sanding processes of hardwood and softwood are significantly different. In the second phase of blunting, sanding belts with higher grit numbers (P120 and P180) behaved similarly while sanding hardwood and softwood. Full article
(This article belongs to the Special Issue Application of Wood Composites)
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13 pages, 6115 KiB  
Article
TOF-SIMS Molecular Imaging and Properties of pMDI-Bonded Particleboards Made from Cup-Plant and Wood
by Petr Klímek, Rupert Wimmer and Peter Meinlschmidt
Appl. Sci. 2021, 11(4), 1604; https://doi.org/10.3390/app11041604 - 10 Feb 2021
Cited by 6 | Viewed by 2237
Abstract
Cup-plant (Silphium perfoliatum L.) stalks were investigated as a potential wood-replacement in particleboards (PBs). Two types of PBs were produced—(1) single-layer and (2) three-layer boards. In the three-layer cup-plant PB, the core layer was made from cup-plant, while the surface layer consisted [...] Read more.
Cup-plant (Silphium perfoliatum L.) stalks were investigated as a potential wood-replacement in particleboards (PBs). Two types of PBs were produced—(1) single-layer and (2) three-layer boards. In the three-layer cup-plant PB, the core layer was made from cup-plant, while the surface layer consisted of spruce particles. The cup-plant as well as spruce control panels were produced with polymeric methylene diphenyl diisocyanate (pMDI) as the adhesive, with the physical and mechanical properties measured to meet class P1 of the European EN 312 standard. For the intrinsic morphology of the particleboards, scanning electron microscopy was applied. Wood-based and cup-plant-based particleboards indicated significant differences in morphology that affect the resulting properties of particleboards. Furthermore, an innovative approach was used in the determination of the pMDI bondline morphology. With a compact Time-of-Flight Secondary Ion Mass analyser, integrated in a multifunctional focused-ion beam scanning-electron-microscope, it was possible to show that the Ga+ ion source could be detect and visualize in 3D ion molecular clusters specific to pMDI adhesive and wood. Mechanical performance data showed that cup-plant particleboards performed well, even though their properties were below the spruce-made controls. Especially the modulus of rupture (MOR) of the cup-plant PB was lowered by 40%, as compared to the spruce-made control board. Likewise, thickness swelling of cup-plant made boards was higher than the control. Results were linked to the specific porous structure of the cup-plant material. In contrast, it was shown that three-layer cup-plant PB had a higher MOR and also a higher modulus of elasticity, along with lower thickness swelling, compared to its single-layer cup-plant counterpart. The industry relevant finding was that the three-layer PB made from cup-plant stalks fulfilled the EN 312 standard, class P1 (usage in dry conditions). It was shown that raw material mixtures could be useful to improve the mechanical panel performance, also with an altered vertical density profile. Full article
(This article belongs to the Special Issue Application of Wood Composites)
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15 pages, 1497 KiB  
Article
Bonding of Selected Hardwoods with PVAc Adhesive
by Ján Iždinský, Ladislav Reinprecht, Ján Sedliačik, Jozef Kúdela and Viera Kučerová
Appl. Sci. 2021, 11(1), 67; https://doi.org/10.3390/app11010067 - 23 Dec 2020
Cited by 13 | Viewed by 2931
Abstract
The bonding of wood with assembly adhesives is crucial for manufacturing wood composites, such as solid wood panels, glulam, furniture parts, and sport and musical instruments. This work investigates 13 hardwoods—bangkirai, beech, black locust, bubinga, ipé, iroko, maçaranduba, meranti, oak, palisander, sapelli, wengé [...] Read more.
The bonding of wood with assembly adhesives is crucial for manufacturing wood composites, such as solid wood panels, glulam, furniture parts, and sport and musical instruments. This work investigates 13 hardwoods—bangkirai, beech, black locust, bubinga, ipé, iroko, maçaranduba, meranti, oak, palisander, sapelli, wengé and zebrano—and analyzes the impact of their selected structural and physical characteristics (e.g., the density, cold water extract, pH value, roughness, and wettability) on the adhesion strength with the polyvinyl acetate (PVAc) adhesive Multibond SK8. The adhesion strength of the bonded hardwoods, determined by the standard EN 205, ranged in the dry state from 9.5 MPa to 17.2 MPa, from 0.6 MPa to 2.6 MPa in the wet state, and from 8.5 MPa to 19.2 MPa in the reconditioned state. The adhesion strength in the dry state of the bonded hardwoods was not influenced by their cold water extracts, pH values, or roughness parallel with the grain. On the contrary, the adhesion strength was significantly with positive tendency influenced by their higher densities, lower roughness parameters perpendicular to the grain, and lower water contact angles. Full article
(This article belongs to the Special Issue Application of Wood Composites)
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16 pages, 6516 KiB  
Article
Alien Wood Species as a Resource for Wood-Plastic Composites
by Sergej Medved, Daša Krapež Tomec, Angela Balzano and Maks Merela
Appl. Sci. 2021, 11(1), 44; https://doi.org/10.3390/app11010044 - 23 Dec 2020
Cited by 11 | Viewed by 2857
Abstract
Since invasive alien species are one of the main causes of biodiversity loss in the region and thus of changes in ecosystem services, it is important to find the best possible solution for their removal from nature and the best practice for their [...] Read more.
Since invasive alien species are one of the main causes of biodiversity loss in the region and thus of changes in ecosystem services, it is important to find the best possible solution for their removal from nature and the best practice for their usability. The aim of the study was to investigate their properties as components of wood-plastic composites and to investigate the properties of the wood-plastic composites produced. The overall objective was to test the potential of available alien plant species as raw material for the manufacture of products. This would contribute to sustainability and give them a better chance of ending their life cycle. One of the possible solutions on a large scale is to use alien wood species for the production of wood plastic composites (WPC). Five invasive alien hardwood species have been used in combination with polyethylene powder (PE) and maleic anhydride grafted polyethylene (MAPE) to produce various flat pressed WPC boards. Microstructural analyses (confocal laser scanning microscopy and scanning electron microscopy) and mechanical tests (flexural strength, tensile strength) were performed. Furthermore, measurements of density, thickness swelling, water absorption and dimensional stability during heating and cooling were carried out. Comparisons were made between the properties of six WPC boards (five alien wood species and mixed boards). The results showed that the differences between different invasive alien wood species were less obvious in mechanical properties, while the differences in sorption properties and dimensional stability were more significant. The analyses of the WPC structure showed a good penetration of the polymer into the lumens of the wood cells and a fine internal structure without voids. These are crucial conditions to obtain a good, mechanically strong and water-resistant material. Full article
(This article belongs to the Special Issue Application of Wood Composites)
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16 pages, 2150 KiB  
Article
Prediction of Mechanical Performance of Acetylated MDF at Different Humid Conditions
by Sheikh Ali Ahmed, Stergios Adamopoulos, Junqiu Li and Janka Kovacikova
Appl. Sci. 2020, 10(23), 8712; https://doi.org/10.3390/app10238712 - 04 Dec 2020
Cited by 4 | Viewed by 2070
Abstract
Change of relative humidity (RH) in surrounding environment can greatly affect the physical and mechanical properties of wood-based panels. Commercially produced acetylated medium density fiberboard (MDF), Medite Tricoya®, was used in this study to predict strength and stiffness under varying humid [...] Read more.
Change of relative humidity (RH) in surrounding environment can greatly affect the physical and mechanical properties of wood-based panels. Commercially produced acetylated medium density fiberboard (MDF), Medite Tricoya®, was used in this study to predict strength and stiffness under varying humid conditions by separating samples in parallel (//) and perpendicular (⊥) to the sanding directions. Thickness swelling, static moduli of elasticity (MOEstat) and rupture (MORstat), and internal bond (IB) strength were measured at three different humid conditions, i.e., dry (35% RH), standard (65% RH) and wet (85% RH). Internal bond (IB) strength was also measured after accelerated aging test. A resonance method was used to determine dynamic modulus of elasticity (MOEdyn) at the aforementioned humid conditions. Linear regression and finite element (FE) analyses were used to predict the MDF’s static bending behavior. Results showed that dimensional stability, MOEstat, MORstat and IB strength decreased significantly with an increase in RH. No reduction of IB strength was observed after 426 h of accelerated aging test. A multiple regression model was established using MOEdyn and RH values to predict MOEstat and MORstat. In both directions (// and ⊥), highly significant relationships were observed. The predicted and the measured values of MOEstat and MORstat were satisfactorily related to each other, which indicated that the developed model can be effectively used for evaluating the strength and stiffness of Medite Tricoya® MDF samples at any humid condition. Percent errors of two different simulation techniques (standard and extended FE method) showed highly efficient way of simulating the MDF structures with low fidelity. Full article
(This article belongs to the Special Issue Application of Wood Composites)
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9 pages, 2391 KiB  
Article
Influence of Grit Size and Wood Species on the Granularity of Dust Particles during Sanding
by Marta Pędzik, Kinga Stuper-Szablewska, Maciej Sydor and Tomasz Rogoziński
Appl. Sci. 2020, 10(22), 8165; https://doi.org/10.3390/app10228165 - 18 Nov 2020
Cited by 20 | Viewed by 2888
Abstract
Wood dust poses a threat to the health of employees and the risk of explosion and fire, accelerates the wear of machines, worsens the quality of processing, and requires large financial outlays for its removal. The aim of this study was to investigate [...] Read more.
Wood dust poses a threat to the health of employees and the risk of explosion and fire, accelerates the wear of machines, worsens the quality of processing, and requires large financial outlays for its removal. The aim of this study was to investigate the extent to which the grit size of sandpaper influences the size of the wood dust particles and the proportion of the finest particles which, when dispersed in the air, may constitute the respirable fraction. Six species of hardwood (beech, oak, ash, hornbeam, alder, and walnut), and three species of softwood (larch, pine, and spruce) were used in the research. While sanding the samples under the established laboratory conditions, the following were measured for two types of sandpapers (grit sizes P60 and P180): mean arithmetic particle size of dust and finest dust particles content (<10 µm). Based on the obtained results, we found that the largest dust particle sizes were obtained for alder, pine, and spruce; the smallest size of dust particles during sanding with both sandpapers was obtained for beech, hornbeam, oak, ash, larch, and walnut. The mean arithmetic particle sizes ranged from 327.98 µm for pine to 104.23 µm for hornbeam. The mean particle size of the dust obtained with P60 granulation paper was 1.4 times larger than that of the dust obtained with P180 granulation sandpaper. The content of the finest dust particles ranged from 0.21% for pine (P60 sandpaper) to 12.58% for beech (P180 sandpaper).The type of wood (hardwood or softwood) has a significant influence on the particle size and the content of the finest dust fraction. Full article
(This article belongs to the Special Issue Application of Wood Composites)
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16 pages, 6149 KiB  
Article
Optimization of Parameters for the Cutting of Wood-Based Materials by a CO2 Laser
by Ivan Kubovský, Ľuboš Krišťák, Juraj Suja, Milada Gajtanska, Rastislav Igaz, Ivan Ružiak and Roman Réh
Appl. Sci. 2020, 10(22), 8113; https://doi.org/10.3390/app10228113 - 16 Nov 2020
Cited by 17 | Viewed by 3944
Abstract
This article deals with the laser cutting of wood and wood composites. The laser cutting of wood and wood composites is widely accepted and used by the wood industry (due to its many advantages compared to, e.g., saw cutting). The goal of this [...] Read more.
This article deals with the laser cutting of wood and wood composites. The laser cutting of wood and wood composites is widely accepted and used by the wood industry (due to its many advantages compared to, e.g., saw cutting). The goal of this research was to optimize the cutting parameters of spruce wood (Pices abies L.) by a low-power CO2 laser. The influence of three factors was investigated, namely, the effect of the laser power (100 and 150 W), cutting speed (3, 6, and 9 mm·s−1), and number of annual rings (3–11) on the width of the cutting kerf on the top board, on the width of the cutting kerf on the bottom board, on the ratio of the cutting kerf width on the top and bottom of the board, on the width of the heat-affected area on both sides of the cutting kerf (this applies to the top and bottom of the board), and on the degree of charring. Analysis of variance (ANOVA) and correlation and regression analysis were used for developing a linear regression model without interactions and a quadratic regression model with quadratic interactions. Based on the developed models, the optimization of parameter settings of the investigated process was performed in order to achieve the final kerf quality. The improvement in the quality of the part ranged from 3% to more than 30%. The results were compared with other research dealing with the laser cutting of wood and wood composites. Full article
(This article belongs to the Special Issue Application of Wood Composites)
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15 pages, 22949 KiB  
Article
Tropical Wood Dusts—Granulometry, Morfology and Ignition Temperature
by Miroslava Vandličková, Iveta Marková, Linda Makovická Osvaldová, Stanislava Gašpercová, Jozef Svetlík and Jozef Vraniak
Appl. Sci. 2020, 10(21), 7608; https://doi.org/10.3390/app10217608 - 28 Oct 2020
Cited by 14 | Viewed by 2754
Abstract
The article considers the granulometric analysis of selected samples of tropical wood dust from cumaru (Dipteryx odorata), padauk (Pterocarpus soyauxii), ebony (Diospyros crassiflora), and marblewood (Marmaroxylon racemosum) using a Makita 9556CR 1400 W grinder and [...] Read more.
The article considers the granulometric analysis of selected samples of tropical wood dust from cumaru (Dipteryx odorata), padauk (Pterocarpus soyauxii), ebony (Diospyros crassiflora), and marblewood (Marmaroxylon racemosum) using a Makita 9556CR 1400 W grinder and K36 sandpaper, for the purpose of selecting the percentages of the various fractions (<63; 63; 71; 200; 315; 500 μm) of wood dust samples. Tropical wood dust samples were made using a hand orbital sander Makita 9556CR 1400 W, and sized using the automatic mesh vibratory sieve machine Retsch AS 200 control. Most dust particles (between 50–79%) from all wood samples were under 100 μm in size. This higher percentage is associated with the risk of inhaling the dust, causing damage to the respiratory system, and the risk of a dust-air explosive mixture. Results of granulometric fractions contribution of tropical woods sanding dust were similar. Ignition temperature was changed by particle sizes, and decreased with a decrease in particle sizes. We found that marblewood has the highest minimum ignition temperature (400–420 °C), and padauk has the lowest (370–390 °C). Full article
(This article belongs to the Special Issue Application of Wood Composites)
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13 pages, 1739 KiB  
Article
Effect of Thermal Treatment of Birch Wood by Saturated Water Vapor on Granulometric Composition of Chips from Sawing and Milling Processes from the Point of View of Its Processing to Composites
by Richard Kminiak, Kazimierz A. Orlowski, Ladislav Dzurenda, Daniel Chuchala and Adrián Banski
Appl. Sci. 2020, 10(21), 7545; https://doi.org/10.3390/app10217545 - 27 Oct 2020
Cited by 22 | Viewed by 1855
Abstract
The goal of this work is to investigate the impact of thermal modification of birch wood with saturated steam on the particle size distribution of the sawing and milling process. Birch wood (Betula pendula Roth) is an excellent source to produce plywood boards. [...] Read more.
The goal of this work is to investigate the impact of thermal modification of birch wood with saturated steam on the particle size distribution of the sawing and milling process. Birch wood (Betula pendula Roth) is an excellent source to produce plywood boards. Wastes from mechanical processing of birch wood are suitable to produce composite materials. Granulometric analyses of chips from sawing processes on the PRW 15M frame saw, as well as on the 5-axis CNC machining centre SCM TECH Z5 and the 5-axis CNC machining centre AX320 Pinnacle, proved that more than 95% of chips are chips of coarse and medium coarse chip fractions with dimensions above 0.125 mm. Depending on the shape, coarse and medium-thick chips belong to the group of fiber chips, the length of which is several times greater than the width and thickness. Fine fractions with dimensions smaller than 125 μm are isometric chips that are approximately the same size in all three dimensions. Thoracic dust fractions below 30 μm were not measured. The performed analyses showed that the heat treatment of birch wood with saturated steam did not affect the grain size of chips formed in sawing and milling processes on CNC machining centre and can be used as a raw material for the production of composite materials. Fabric filters are suitable for separating chips extracted from frame saws, PRW-15M or machining centre. Environmental criteria for the separation of chips from transport air in textile filters are met by filters with a fabric classified in class G4. Full article
(This article belongs to the Special Issue Application of Wood Composites)
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12 pages, 1350 KiB  
Article
Structural Application of Eco-Friendly Composites from Recycled Wood Fibres Bonded with Magnesium Lignosulfonate
by Petar Antov, Vassil Jivkov, Viktor Savov, Ralitsa Simeonova and Nikolay Yavorov
Appl. Sci. 2020, 10(21), 7526; https://doi.org/10.3390/app10217526 - 26 Oct 2020
Cited by 31 | Viewed by 2752
Abstract
The pulp and paper industry generates substantial amounts of solid waste and wastewater, which contain waste fibres. The potential of using these recycled wood fibres for producing eco-friendly composites that were bonded with a formaldehyde-free adhesive (magnesium lignosulfonate) and their use in structural [...] Read more.
The pulp and paper industry generates substantial amounts of solid waste and wastewater, which contain waste fibres. The potential of using these recycled wood fibres for producing eco-friendly composites that were bonded with a formaldehyde-free adhesive (magnesium lignosulfonate) and their use in structural applications was evaluated in this study. Fibreboards were produced in the laboratory with a density of 720 kg·m−3 and 15% magnesium lignosulfonate gluing content, based on the dry fibres. The mechanical properties (bending strength, modulus of elasticity and internal bond strength), physical properties (thickness swelling and water absorption) and formaldehyde content were determined and compared with the European Standards requirements for wood-based panels. In general, the laboratory-produced panels demonstrated acceptable mechanical properties, such as bending strength (18.5 N·mm−2) and modulus of elasticity (2225 N·mm−2), which were higher than the minimum requirements for type P2 particleboards and equal to the requirements for MDF panels. The moisture properties, i.e., thickness swelling (24 h) and water absorption (24 h) significantly deteriorated. The free formaldehyde content of the laboratory-produced composites (1.1 mg/100 g) reached the super E0 grade (≤1.5 mg/100 g), which allowed for their classification as eco-friendly, low-emission wood-based composites. The L-type corner joints, made from the developed composites, demonstrated significantly lower bending capacity (from 2.5 to 6.5 times) compared to the same joints made from MDF panels. Nevertheless, the new eco-friendly composites can be efficiently utilised as a structural material in non-load-bearing applications. Full article
(This article belongs to the Special Issue Application of Wood Composites)
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14 pages, 4162 KiB  
Article
Formaldehyde Emission in Micron-Sized Wollastonite-Treated Plywood Bonded with Soy Flour and Urea-Formaldehyde Resin
by Hamid R. Taghiyari, Seyed Behzad Hosseini, Saman Ghahri, Mohammad Ghofrani and Antonios N. Papadopoulos
Appl. Sci. 2020, 10(19), 6709; https://doi.org/10.3390/app10196709 - 25 Sep 2020
Cited by 32 | Viewed by 2823
Abstract
Soy flour was partly substituted for urea-formaldehyde (UF) resin with different content to investigate its effect on formaldehyde emission in three-layer plywood panels. In each square meter of panels, 300 g of resin was used (wet weight basis of resin). Micron-sized wollastonite was [...] Read more.
Soy flour was partly substituted for urea-formaldehyde (UF) resin with different content to investigate its effect on formaldehyde emission in three-layer plywood panels. In each square meter of panels, 300 g of resin was used (wet weight basis of resin). Micron-sized wollastonite was added to the resin mixture at 5% and 10% consumption levels (wet weight basis of resin) to determine its potential effects as a reinforcing filler to mitigate the negative effects of addition of soy flour. Results showed a decreasing trend in formaldehyde emission as soy flour content increased to 20%. The highest shear-strength values were observed in panels with 10% and 15% soy flour content. The addition of wollastonite did not have a significant effect on formaldehyde emission, but it decreased the shear strength in soy-treated panels, although the values were still higher than those of control panels. Wollastonite significantly mitigated the negative effects of soy flour on the water absorption and thickness swelling of panels. It was concluded that 10% of soy flour and 5% of wollastonite provided the lowest formaldehyde emission and the most optimum physical and mechanical properties. Full article
(This article belongs to the Special Issue Application of Wood Composites)
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15 pages, 3138 KiB  
Article
Comparative Studies on Two Types of OSB Boards Obtained from Mixed Resinous and Fast-growing Hard Wood
by Aurel Lunguleasa, Adela-Eliza Dumitrascu and Valentina-Doina Ciobanu
Appl. Sci. 2020, 10(19), 6634; https://doi.org/10.3390/app10196634 - 23 Sep 2020
Cited by 9 | Viewed by 2896
Abstract
The paper aims to compare the oriented strand boards (OSBs) made in the laboratory from a mixture of softwood species to those made from hardwood species, followed by their comparison to European and industry standards. In this regard, the main properties of the [...] Read more.
The paper aims to compare the oriented strand boards (OSBs) made in the laboratory from a mixture of softwood species to those made from hardwood species, followed by their comparison to European and industry standards. In this regard, the main properties of the panels made in the laboratory were determined, including density, absorption, and swelling in thickness, modulus of elasticity, modulus of rupture, and internal bond. The analysis of the properties of swelling (24 h) and absorption (24 h) revealed that the mixture of softwood species was slightly better thanthe hardwood one. It was also shown that the panels manufactured from the mixture of hardwood species had better mechanical properties than those made of the softwood mixture (modulus of rupture (MOR) = 43.48 N/mm2, modulus of elasticity (MOE) = 7253 N/mm, and internal bond (IB) = 1.57 N/mm2). Additionally, the comparative analysis of properties indicates that the density is highly significant in determining the MOE values of the OSBs. This will allow softwood speciestobe replaced with other species of soft and fast-growing deciduous trees such as willow, birch, and poplar in the manufacture of oriented strand boards. Full article
(This article belongs to the Special Issue Application of Wood Composites)
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11 pages, 1080 KiB  
Article
Walnut and Hazelnut Shells: Untapped Industrial Resources and Their Suitability in Lignocellulosic Composites
by Marius Cătălin Barbu, Thomas Sepperer, Eugenia Mariana Tudor and Alexander Petutschnigg
Appl. Sci. 2020, 10(18), 6340; https://doi.org/10.3390/app10186340 - 11 Sep 2020
Cited by 29 | Viewed by 4317
Abstract
Walnut and hazelnut shells are agricultural by-products, available in high quantities during the harvest season. The potential of using these two agricultural residues as raw materials in particleboard production has been evaluated in this study. Different panels with either walnut or hazelnut shells [...] Read more.
Walnut and hazelnut shells are agricultural by-products, available in high quantities during the harvest season. The potential of using these two agricultural residues as raw materials in particleboard production has been evaluated in this study. Different panels with either walnut or hazelnut shells in combination with melamine-urea formaldehyde or polyurethane at the same level of 1000 kg/m3 density were produced in a laboratory hot press and mechanical properties (modulus of elasticity, bending strength, and Brinell hardness) and physical properties (thickness swelling and water absorption) were determined, together with formaldehyde content. Although Brinell hardness was 35% to 65% higher for the nutshell-based panels, bending strength and modulus of elasticity were 40% to 50% lower for the melamine-urea formaldehyde bonded nutshells compared to spruce particleboards, but was 65% higher in the case of using polyurethane. Water absorption and thickness swelling could be reduced significantly for the nutshell-based boards compared to the spruce boards (the values recorded ranged between 58% to 87% lower as for the particleboards). Using polyurethane as an adhesive has benefits for water uptake and thickness swelling and also for bending strength and modulus of elasticity. The free formaldehyde content of the lignocellulosic-based panels was included in the E0 category (≤2.5 mg/100 g) for both walnut and hazelnut shell raw materials and the use of polyurethane improved these values to super E0 category (≤1.5 mg/100 g). Full article
(This article belongs to the Special Issue Application of Wood Composites)
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16 pages, 4182 KiB  
Article
Impact of Structural Defects on the Surface Quality of Hardwood Species Sliced Veneers
by Vasiliki Kamperidou, Efstratios Aidinidis and Ioannis Barboutis
Appl. Sci. 2020, 10(18), 6265; https://doi.org/10.3390/app10186265 - 09 Sep 2020
Cited by 11 | Viewed by 2252
Abstract
The surface roughness constitutes one of the most critical properties of wood and wood veneers for their extended utilization, affecting the bonding ability of the veneers with one another in the manufacturing of wood composites, the finishing, coating and preservation processes, and the [...] Read more.
The surface roughness constitutes one of the most critical properties of wood and wood veneers for their extended utilization, affecting the bonding ability of the veneers with one another in the manufacturing of wood composites, the finishing, coating and preservation processes, and the appearance and texture of the material surface. In this research work, logs of five significant European hardwood species (oak, chestnut, ash, poplar, cherry) of Balkan origin were sliced into decorative veneers. Their surface roughness was examined by applying a stylus tracing method, on typical wood structure areas of each wood species, as well as around the areas of wood defects (knots, decay, annual rings irregularities, etc.), to compare them and assess the impact of the defects on the surface quality of veneers. The chestnut veneers presented the smoothest surfaces, while ash veneers, despite the higher density, recorded the highest roughness. In most of the cases, the roughness was found to be significantly lower around the defects, compared to the typical structure surfaces, probably due to lower porosity, higher density and the presence of tensile wood. The results reveal that the presence of defects does not affect the roughness of the veneers and increases neither the processing requirements of the veneer sheets before finishing, nor the respective production cost of veneers and the veneer-based wood panels. The high utilization prospects of the examined wood species in veneer production, even those bearing various defects, is highlighted. Full article
(This article belongs to the Special Issue Application of Wood Composites)
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14 pages, 4366 KiB  
Article
Utilization of Partially Liquefied Bark for Production of Particleboards
by Wen Jiang, Stergios Adamopoulos, Reza Hosseinpourpia, Jure Žigon, Marko Petrič, Milan Šernek and Sergej Medved
Appl. Sci. 2020, 10(15), 5253; https://doi.org/10.3390/app10155253 - 30 Jul 2020
Cited by 13 | Viewed by 3230
Abstract
Bark as a sawmilling residue can be used for producing value-added chemicals and materials. This study investigated the use of partially liquefied bark (PLB) for producing particleboard with or without synthetic adhesives. Maritime pine (Pinus pinaster Ait.) bark was partially liquefied in [...] Read more.
Bark as a sawmilling residue can be used for producing value-added chemicals and materials. This study investigated the use of partially liquefied bark (PLB) for producing particleboard with or without synthetic adhesives. Maritime pine (Pinus pinaster Ait.) bark was partially liquefied in the presence of ethylene glycol and sulfuric acid. Four types of particleboard panels were prepared with a PLB content of 4.7%, 9.1%, 20%, and 33.3%, respectively. Another five types of particleboard panels were manufactured by using similar amounts of PLB and 10 wt.% of melamine–urea–formaldehyde (MUF) adhesives. Characterization of bark and solid residues of PLB was performed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and automated vapor sorption (AVS). Mechanical and physical properties of the particleboard were tested according to the European standards EN 310 for determining modulus of elasticity and bending strength, EN 317 for determining thickness swelling after immersion in water, and EN 319 for determining internal bond strength. The results showed that the increase in PLB content improved the mechanical strength for the non-MUF boards, and the MUF-bonded boards with up to 20% of PLB met the requirements for interior uses in dry conditions according to EN 312. The non-MUF boards containing 33.3% of PLB and the MUF-bonded boards showed comparable thickness swelling and water absorption levels compared to the reference board. Full article
(This article belongs to the Special Issue Application of Wood Composites)
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Review

Jump to: Editorial, Research

12 pages, 4715 KiB  
Review
The Design Development of the Sliding Table Saw Towards Improving Its Dynamic Properties
by Kazimierz A. Orlowski, Przemyslaw Dudek, Daniel Chuchala, Wojciech Blacharski and Tomasz Przybylinski
Appl. Sci. 2020, 10(20), 7386; https://doi.org/10.3390/app10207386 - 21 Oct 2020
Cited by 9 | Viewed by 5703
Abstract
Cutting wood with circular saws is a popular machining operation in the woodworking and furniture industries. In the latter sliding table saws (panel saws) are commonly used for cutting of medium density fiberboards (MDF), high density fiberboards (HDF), laminate veneer lumber (LVL), plywood [...] Read more.
Cutting wood with circular saws is a popular machining operation in the woodworking and furniture industries. In the latter sliding table saws (panel saws) are commonly used for cutting of medium density fiberboards (MDF), high density fiberboards (HDF), laminate veneer lumber (LVL), plywood and chipboards of different structures. The most demanded requirements for machine tools are accuracy and precision, which mainly depend on the static deformation and dynamic behavior of the machine tool under variable cutting forces. The aim of this study is to present a new holistic approach in the process of changing the sliding table saw design solutions in order to obtain a better machine tool that can compete in the contemporary machine tool market. This study presents design variants of saw spindles, the changes that increase the critical speeds of spindles, the measurement results of the dynamic properties of the main drive system, as well as the development of the machine body structure. It was proved that the use of only rational imitation in the spindle design on the basis of the other sliding table saws produced does not lead to the expected effect in the form of correct spindle operation. Full article
(This article belongs to the Special Issue Application of Wood Composites)
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