Applied Sciences

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7 pages, 204 KiB

Open AccessEditorial

Special Issue “International Conference Wood Science and Engineering in the Third Millennium—ICWSE 2023”

by Lidia Gurau, Mihaela Campean and Emilia-Adela Salca

Appl. Sci. 2024, 14(13), 5800; https://doi.org/10.3390/app14135800 - 3 Jul 2024

Viewed by 791

Abstract

Every two years, the Faculty of Furniture Design and Wood Engineering of the Transilvania University of Brasov organises an international conference on wood science and engineering—ICWSE, which was held for the 13th in November 2023 and hosted over 100 participants from 30 countries [...] Read more.

Every two years, the Faculty of Furniture Design and Wood Engineering of the Transilvania University of Brasov organises an international conference on wood science and engineering—ICWSE, which was held for the 13th in November 2023 and hosted over 100 participants from 30 countries worldwide [...] Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

Research

Jump to: Editorial, Review

17 pages, 2976 KiB

Open AccessArticle

Selected Physical and Mechanical Properties of Subfossil Oak (Quercus spp.) Compared to Aged Oak and Recent Oak

by Ruxandra Nedelcu, Maria Cristina Timar, Mihaela Porojan and Emanuela Carmen Beldean

Appl. Sci. 2024, 14(8), 3294; https://doi.org/10.3390/app14083294 - 13 Apr 2024

Viewed by 1070

Abstract

Subfossil oak (SO) wood material, originating from three different buried trunks discovered in recent years by excavations in riverbanks on Romanian territory, was analysed in this research. Aged oak recovered from constructions (AO_C) and recent/new oak wood material (NO) were also investigated to [...] Read more.

Subfossil oak (SO) wood material, originating from three different buried trunks discovered in recent years by excavations in riverbanks on Romanian territory, was analysed in this research. Aged oak recovered from constructions (AO_C) and recent/new oak wood material (NO) were also investigated to provide comparative data for the SO. The oven-dry density and the basic density, the total volumetric and linear swelling and shrinkage coefficients and the compression strength parallel to the grain were the selected physical and mechanical properties considered. The experimental results showed a lower density of SO compared to NO and AO_C tested by up to about 19–20%, alongside a trend of increased dimensional instability, with variability among the tested assortments. The compression strength parallel to the grain was reduced by 19–31% compared to NO. The properties of AO-C were closer to those of NO, but differences between wood materials from different sources and of different ages were registered. A positive linear correlation was found between compression strength parallel to grain and the basic density for all types of material and assortments tested. These comparative results have to be considered by designers and engineers in the valorisation of SO in furniture design and other applications. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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24 pages, 4540 KiB

Open AccessArticle

Light-Induced Colour Changes in Wood Surfaces in Indoor Conditions Determined by an Artificial Accelerated Test: Influence of Wood Species and Coating Materials

by Mihai-Junior Torcătoru and Maria Cristina Timar

Appl. Sci. 2024, 14(3), 1226; https://doi.org/10.3390/app14031226 - 1 Feb 2024

Cited by 1 | Viewed by 1296

Abstract

Stabilising the natural colour of wood species exposed to light in indoor conditions is a challenge that could be better addressed based on a deeper understanding of the occurring phenomena and influencing factors. This paper investigates comparatively the light-induced colour changes for three [...] Read more.

Stabilising the natural colour of wood species exposed to light in indoor conditions is a challenge that could be better addressed based on a deeper understanding of the occurring phenomena and influencing factors. This paper investigates comparatively the light-induced colour changes for three hardwood species, namely, European maple (Acer pseudoplatanus L.), European ash (Fraxinus excelsior L.) and European walnut (Juglans regia L.), as well as the influence of finishing with three types of clear, colourless waterborne lacquers: acrylic-polyurethane (F1), acrylic (F2) and polyurethane (F3) on their colour stability. Colour measurements in the CIELab system in conjunction with an artificial accelerated ageing test under the action of UV-VIS radiation, simulating natural light passing through window glass, and two types of test samples were employed to highlight the influence and contributions of the wood substrate and of the coating films to the global colour modifications. Coating films applied on 1 mm clear glass slides were employed as a sort of “detachable” finish for this purpose. Direct exposure to UV-VIS light caused visible colour changes for both uncoated and coated wood surfaces, the values of the calculated colour differences (ΔE) after a 72 h exposure being dependant on both the wood species and the coating material. Excepting two situations for walnut, statistically significantly higher colour differences were obtained for the uncoated samples: maple (9.36 units), ash (8.39 units), walnut (6.20 units), compared to the coated ones: maple (4.92–5.71 units), ash (2.25–3.94 units), walnut (4.74–7.70 units). The wood substrates underlying the coating films were found to bring the maximum contribution to the overall colour changes in the clear coated surfaces, while the coating films employed in this research demonstrated a fairly good colour stability to UV-VIS light exposure, with maximum colour changes (∆E) up to only 1.30 units. Overall, the wood species and the type of coating were found as influencing factors in interaction with the light-induced colour changes in wood surfaces in indoor conditions. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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16 pages, 9555 KiB

Open AccessArticle

Date-Palm-Based Sustainable Hybrid Composite with Cotton and Kevlar Fibre Participation

by Octavia Zeleniuc, Mohammad Hassan Mazaherifar, Camelia Coșereanu and Andrei Suciu

Appl. Sci. 2024, 14(3), 1008; https://doi.org/10.3390/app14031008 - 24 Jan 2024

Cited by 3 | Viewed by 1244

Abstract

This research aims to evaluate the physical and mechanical performance of three types of hybrid composites made of date palm (Phoenix dactylifera L.) (DP), additional layers of cotton (DP/C) and Kevlar fibres (DP/K). The fibres were formed into flat sheets and employed [...] Read more.

This research aims to evaluate the physical and mechanical performance of three types of hybrid composites made of date palm (Phoenix dactylifera L.) (DP), additional layers of cotton (DP/C) and Kevlar fibres (DP/K). The fibres were formed into flat sheets and employed as reinforcement layers embedded in a polyester matrix. Three-layer and five-layer hybrid composites were created using the hand layup method. The layers have alternative longitudinal–transversal orientation. The composites were investigated for density, thickness swelling (TS), water absorption (WA), flexural strength and modulus of elasticity (MOE) properties. Moreover, the composites were subjected to cycles of water immersion, freezing and drying, and the changes in mass and mechanical performance were analysed before and after the cyclic testing. The hybrid composite with Kevlar as the inner layers displayed better physical and mechanical properties when compared to the other two hybrid composites. A stereo-microscopic investigation revealed that poor adhesion between the layers of composites contributed to a reduction in the mechanical properties of DP/C and DP hybrid composites. The DP/C composite had the highest thickness swelling and water absorption, with the water uptake more pronounced than in the cases of the other composites. The hybridisation of date palms with Kevlar fibres improved the properties of the hybrid composites. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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22 pages, 6431 KiB

Open AccessArticle

Designing Multi-Functional Magnetic Storage Cubes for Use in Modern Homes and Schools

by Martin Zach, Jiří Tauber, Přemysl Dohnal and Jaroslav Svoboda

Appl. Sci. 2024, 14(2), 829; https://doi.org/10.3390/app14020829 - 18 Jan 2024

Viewed by 1269

Abstract

Using modern methodologies in the sectors and subareas of industrial design, where they currently find only marginal application, brings a potential for interrelating technology, the arts, and fine arts. To illustrate this, we present model procedures and options for designing a versatile storage [...] Read more.

Using modern methodologies in the sectors and subareas of industrial design, where they currently find only marginal application, brings a potential for interrelating technology, the arts, and fine arts. To illustrate this, we present model procedures and options for designing a versatile storage cube that integrates magnetic structural components facilitating easy and quick assembly. In addition to being an item of real furniture, portable and readily convertible into a table or soft stool, the cube supports children’s creative games and helps to develop their overall skills in the present-day household and in pre-primary and primary education. The basic material rests in birch plywood, and the joint edges between the individual walls are covered with smooth plastic guards manufactured via additive 3D printing from corn fodder-based filament. Thus, an interesting structural detail, namely, plastic edges, is generated, reinforcing the entire product. The walls comprise decorative, multicolor, polyurethane foam-based elements that can be removed and reinserted. Regarding the manufacturing technology, CNC machining and laser shaping are widely employed on the main parts, and the plastic edges are 3D-printed. In terms of the original idea, the product responds to customer requirements within a specific design project. The robustness and stability tests have proved that the cubes fully satisfy the relevant standards. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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15 pages, 3510 KiB

Open AccessArticle

Gloss Level, Type of Paper and Colour of HDF Boards Finished with the Energy-Saving Acrylic Paint System

by Milena Henke, Tomasz Krystofiak, Emilia Adela Salca and Barbara Lis

Appl. Sci. 2024, 14(1), 394; https://doi.org/10.3390/app14010394 - 31 Dec 2023

Viewed by 1423

Abstract

The global drive to eliminate mercury is stimulating the development of LED lamps for UV curing of coatings. Despite its many advantages, the transition to this system in the furniture industry presents technological issues. This paper aimed to determine the impact of the [...] Read more.

The global drive to eliminate mercury is stimulating the development of LED lamps for UV curing of coatings. Despite its many advantages, the transition to this system in the furniture industry presents technological issues. This paper aimed to determine the impact of the paint line’s individual technological and process parameters on the coating’s optical properties, such as colour and gloss of furniture components made of white-coloured light-weight boards. Samples were prepared under the conditions of an industrial paint line using LED and traditional mercury lamps at the rate of 50 m/min. The colour was tested using the CIELAB system on a BYK GARDNER spectrophotometer, while the gloss was measured using the PICO GLOSS meter. Based on the data obtained, the optical parameters were found to be highly stable irrespective of the power drop in the LED lamps. The coordinates L*, b* and gloss G were affected by the amount of topcoat and basecoat, the number of coats, the mercury lamps’ power and the panel grinding programs used. The results of the tests showed that high L* and b* values could be achieved by increasing the number of overlays. This solution also ensures less basecoat and topcoat consumption, contributing to large material savings. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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14 pages, 5006 KiB

Open AccessArticle

Adhesion of Varnish Coatings as a Background for Analogue and Digital Printing Technologies

by Maciej Tokarczyk, Barbara Lis, Emilia Adela Salca and Tomasz Krystofiak

Appl. Sci. 2024, 14(1), 304; https://doi.org/10.3390/app14010304 - 29 Dec 2023

Cited by 1 | Viewed by 1103

Abstract

In analogue and digital printing technologies, from 3 up to 12 layers of lacquer products are applied. Technological parameters significantly influence the adhesion in the coating system. This article refers to the analysis of the influence of selected technological parameters, such as the [...] Read more.

In analogue and digital printing technologies, from 3 up to 12 layers of lacquer products are applied. Technological parameters significantly influence the adhesion in the coating system. This article refers to the analysis of the influence of selected technological parameters, such as the number of layers, energy doses distributed by the radiators, and line speed, on the topography and adhesion of varnish coatings formed in the process of varnishing with rollers and UV-curing systems. The appropriately prepared surface can be used as a background layer for the analogue and digital printing technology. Manufacturers must adapt the production process to the particular varnish to obtain finished products with the best possible performance properties. The state of surface free energy and finally adhesion can be assessed by theoretically determining the possibility of an adhesive bonding between the product and the substrate, taking into account the assumptions of the adsorption theory of adhesion and measurement of the contact angle (Θ). An experimental confirmation of adhesion measurements included removing the coatings from the substrate via stamps glued to the coating. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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25 pages, 3037 KiB

Open AccessArticle

Wood Material Properties of Forest Fire-Damaged Norway Spruce and Scots Pine for Mechanical Wood Processing in Finland

by Juhani Marttila, Veikko Möttönen, Antti Haapala, Pekka Ylimäki, Petri Kilpeläinen and Erkki Verkasalo

Appl. Sci. 2024, 14(1), 238; https://doi.org/10.3390/app14010238 - 27 Dec 2023

Cited by 2 | Viewed by 1711

Abstract

Due to climate change, the risk of forest fires has increased in Europe, resulting in challenges in the allocation of salvaged wood. We studied the raw material potential for wood products of Norway spruce and Scots pine sawn log trees that remained standing [...] Read more.

Due to climate change, the risk of forest fires has increased in Europe, resulting in challenges in the allocation of salvaged wood. We studied the raw material potential for wood products of Norway spruce and Scots pine sawn log trees that remained standing after a large forest fire in Kalajoki, Finland, in July 2021. Eight burned trees, with four reference trees per species, were sampled as standard specimens, and measurements were analyzed with linear mixed models. The effects of fire on the modulus of elasticity and rupture, Brinell hardness, moisture gradient, and color were measured on clear wood specimens of sapwood and heartwood. The wood density, level of fire damage, and height location of a tree were used as additional predictors. The results show some changes in the sapwood material. Spruce wood underwent stronger changes after the fire than pine wood, probably due to spruce wood having a thinner bark and a longer crown. The moisture content decreased in spruce, and the color darkened in both spruce and pine. Changes in the mechanical properties were mostly negligible, but a small increase in the Brinell hardness in spruce and a small decrease in the modulus of rupture in pine were observed. Fresh salvaged wood can be a suitable material for middle-quality and lower-quality wood products. The spread of char and soot into wood and wood processing machinery still limits its usage, especially for spruce. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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21 pages, 6875 KiB

Open AccessArticle

A Stratified Characterization of Surface Quality of Beech Processed by Profile Milling

by Luminița-Maria Brenci and Lidia Gurău

Appl. Sci. 2024, 14(1), 129; https://doi.org/10.3390/app14010129 - 22 Dec 2023

Cited by 1 | Viewed by 804

Abstract

The evaluation of surface quality after milling still represents a challenge due to the stratified structure of wood. In this paper, the surface quality of beech wood obtained by profile milling was analyzed differentiating between tool marks, fuzzy grain, and accidental surface gaps [...] Read more.

The evaluation of surface quality after milling still represents a challenge due to the stratified structure of wood. In this paper, the surface quality of beech wood obtained by profile milling was analyzed differentiating between tool marks, fuzzy grain, and accidental surface gaps overlapped onto the deep anatomical cavities. The samples were milled at two rotation speeds, 3308 rpm (n₁) and 6594 rpm (n₂), and two feed speeds of 6.53 m/min (v_f1) and 23.74 m/min (v_f2). After the samples were cut, approximately 600 m of beech wood were further processed before measuring the surface quality again. The surface waviness measured by Wa increased more than double when the feed speed increased from v_f1 to v_f2. Rk increased with the feed speed (with the feed per tooth, f_z, for a constant n, respectively) for n₂ by a significant 57%. An increase in the rotation speed from n₁ to n₂ has reduced Rk, but the effect was not significant. The processing quality, Rk, measured at different depths did not differ statistically, in spite of the local differences in the cutting speed. The moment of measuring the surface roughness, such as immediately after sharpening or after a working period, influenced the surface quality. After the tool processed 600 m of beech material, the surface quality improved by 30%. The statistical analysis showed that the most important factor affecting the surface quality was the feed speed (implicitly f_z, for constant n and number of cutters). Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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15 pages, 2352 KiB

Open AccessArticle

Chemical Composition and Color of Short-Rotation Teak Wood Thermally Modified in Closed and Open Systems

by Felipe da Silva Gomes, Miquéias de Souza Reis, Anna Clara Oliveira Rupf, Paulo Henrique dos Santos Silvares, Jessica Sabrina da Silva Ferreira, Luciano da Costa Dias, João Paulo Sardo Madi, Pedro Henrique Gonzalez de Cademartori, Humberto Fantuzzi Neto, Juarez Benigno Paes and Djeison Cesar Batista

Appl. Sci. 2023, 13(24), 13050; https://doi.org/10.3390/app132413050 - 7 Dec 2023

Cited by 2 | Viewed by 1150

Abstract

Although the effect of thermal modification (TM) on teak wood color is well documented, few studies have been carried out on closed-system processes, and it remains unclear what the effect is of different processes on the same material. This work aimed to verify [...] Read more.

Although the effect of thermal modification (TM) on teak wood color is well documented, few studies have been carried out on closed-system processes, and it remains unclear what the effect is of different processes on the same material. This work aimed to verify the effect of closed- and open-system processes of TM on the color of short-rotation teak wood. Thermally modified wood (TMW) was evaluated in a closed system at 160 °C (CS160) and in an open system at 185 °C and 210 °C (OS185 and OS210). We measured the moisture content (initial and final) of the wood and the corrected mass loss (CML). The chemical analyses encompassed the contents of alpha-cellulose, hemicelluloses, lignin, and extractives (total, in acetone and dichloromethane). Wood color was measured before and after TM according to the CIEL*a*b* color space. It was possible to achieve the same color using different processes of thermal modification (CS160 and OS210). TM reduced wood lightness (L*), red–green chromaticity coordinate (a*), and yellow–blue chromaticity coordinate (b*). L* and a* had the biggest and smallest variations, respectively. TMW color was significantly changed, even at the mildest condition tested (OS185, 0.33% CML). Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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10 pages, 3279 KiB

Open AccessArticle

An Overview of the Current Situation of European Poplar Cultures with a Main Focus on Hungary

by Szabolcs Komán, Róbert Németh and Mátyás Báder

Appl. Sci. 2023, 13(23), 12922; https://doi.org/10.3390/app132312922 - 2 Dec 2023

Cited by 2 | Viewed by 1409

Abstract

Among fast-growing wood species, poplars (Populus spp.) can be grown well. Thanks to their valuable wood, they also play an important role in the world. In Europe, regarding poplar forest areas, Hungary is ranked second, where the territorial proportion of poplars has [...] Read more.

Among fast-growing wood species, poplars (Populus spp.) can be grown well. Thanks to their valuable wood, they also play an important role in the world. In Europe, regarding poplar forest areas, Hungary is ranked second, where the territorial proportion of poplars has not changed in the past ten years, and currently, two-thirds of them are constituted by two species. The proportion of grey poplar (P. × canescens) is 42%, while the proportion of ’Pannonia’ hybrid (P. × euramericana cv. Pannonia) is 22%. With regard to gross wood production, they are second after black locust (Robinia pseudoacacia), and their standing tree volume is significant for up to 30 years of age. The average age of hybrid poplars is 21 years, while that of the natives is 26 years. Its wood is used by the packaging industry (pallets and boxes) and the furniture industry (700,000 m³), the plywood industry (200,000 m³), and the fiber industry (300,000 m³), but it is also an important source for energetic purposes (150,000 m³). Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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11 pages, 2948 KiB

Open AccessArticle

The Influence of Slicing Thickness on the Perpendicular to Grain Tensile Properties of Oak (Quercus robur L. and Quercus petraea L.) Lamellae

by Victor Grubîi and Jimmy Johansson

Appl. Sci. 2023, 13(22), 12254; https://doi.org/10.3390/app132212254 - 13 Nov 2023

Viewed by 1014

Abstract

The mechanical properties of sliced lamellae are critical for structural and decorative engineered wood products. This study evaluates the impact of slicing thickness on the tensile mechanical properties of plain oak (Quercus robur L. and Quercus petraea L.) sliced lamellae, perpendicular to [...] Read more.

The mechanical properties of sliced lamellae are critical for structural and decorative engineered wood products. This study evaluates the impact of slicing thickness on the tensile mechanical properties of plain oak (Quercus robur L. and Quercus petraea L.) sliced lamellae, perpendicular to the grain direction. The mechanical performance parameters in terms of the modulus of rupture (MOR), strain at break, and modulus of elasticity (MOE), were analysed using a one-way analysis of variance (ANOVA) and contrast analysis. Our findings indicate that slicing thickness substantially affects the mechanical properties of the modulus of rupture and strain at break, whilst the modulus of elasticity was somewhat independent of the slicing thickness. The mean MOR value increased from 0.8 to 1.43 N mm⁻² for an increase in the sliced lamellae thickness from 1.5 to 4.5 mm. The strain at break increased, on average, from 1.37 to 2.64% for an increase in the sliced lamellae thickness from 1.5 to 4.5 mm. The MOE was approximately 100–120 N mm⁻², indicating a substantially reduced stiffness compared to other sliced lamellae species and solid oak reported values. The slicing check depth ratio diminished from approximately 69% to 50% for an increase in the sliced lamellae thickness from 1.5 mm to 4.5 mm. These findings indicate a negative correlation between the slicing check depth ratio and the tensile performance perpendicular to the grain, suggesting the importance of obtaining an optimal slicing quality. This study employs digital image correlation (DIC) analysis to gain insights into the fracture mechanisms of the tested sliced lamellae and provides an alternative method for strain and stress measuring. The DIC analysis highlighted the role of slicing checks in the stress concentration and ultimate failure areas. This research provides insights into the fracture behaviour of sliced lamellae that are perpendicular to the grain, which is critical for the performance of both structural and decorative products. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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13 pages, 9779 KiB

Open AccessArticle

Application of Additive Manufacturing Technology for Chair Parts Connections

by Antoniu Nicolau, Mihai Alin Pop, Sergiu Valeriu Georgescu and Camelia Coșereanu

Appl. Sci. 2023, 13(21), 12044; https://doi.org/10.3390/app132112044 - 4 Nov 2023

Viewed by 1728

Abstract

Additive manufacturing (AM) is a potential technology to be applied for replacing wood joints in the furniture industry. Overall, 3D-printed connectors have a lot of advantages in chair construction: the possibility of improving the design by using colored materials and new concepts with [...] Read more.

Additive manufacturing (AM) is a potential technology to be applied for replacing wood joints in the furniture industry. Overall, 3D-printed connectors have a lot of advantages in chair construction: the possibility of improving the design by using colored materials and new concepts with no limits of shape and size, avoiding the use of synthetic materials such as adhesives and finishing materials. The present research shows the results of the research conducted on 3D-printed connectors for a chair leg-stretchers joint. Larch (Larix decidua Mill.) wood was used for chair components and selective laser sintering (SLS) technology was employed for the 3D-printing connector designed to assemble the chair elements. Diagonal tensile and compression tests were performed on the L-type joints with 3D-printed connectors and the bending moments were determined and compared to the results obtained after testing the leg-stretchers mortise–tenon joints made of larch wood, taken as a reference. Micrograph investigation was finally performed on the broken areas of the 3D-printed connectors as a result of mechanical testing failures. The results show that the SLS printing technology applied to build the connector does not ensure enough strength to the assembly, and changes in printing parameters are needed for further research, in terms of laser power and scan speed. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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16 pages, 9877 KiB

Open AccessArticle

Properties of Un-Torrefied and Torrefied Poplar Plywood (PW) and Medium-Density Fiberboard (MDF)

by Cosmin Spîrchez, Aurel Lunguleasa, Carmen-Mihaela Popescu, Anamaria Avram and Constantin Stefan Ionescu

Appl. Sci. 2023, 13(21), 11950; https://doi.org/10.3390/app132111950 - 1 Nov 2023

Viewed by 1065

Abstract

In a context where there is an increasing need for thermal treatments of wooden products, the current research contributes a description of the torrefaction treatment of two of the composite wood materials available on the international market. The present paper presents the importance [...] Read more.

In a context where there is an increasing need for thermal treatments of wooden products, the current research contributes a description of the torrefaction treatment of two of the composite wood materials available on the international market. The present paper presents the importance of the torrefaction process for poplar plywood and medium-density fiberboard. In this paper, the positive aspects of the torrefaction process (decrease in water absorption, thickness swelling and shrinkage, and color) but also the negative aspects of mechanical resistance to static bending are presented. Poplar plywood (PW) and medium-density fiberboard (MDF) panels, with the initial dimensions of 2000 × 1250 mm, were used. From these, 300 × 300 mm samples were cut and torrefied using two different temperatures (170 and 190 °C) and two different periods (for 1 and 2 h). After the treatment, the samples were cut in different sizes (as necessary for each type of evaluation method) from different zones of the panels and used to evaluate the water absorption and thickness swelling, to determine their modulus of rupture, roughness, and color changes. The obtained results emphasize that the mass loses increase at high temperature as the main disadvantageous characteristics of torrefaction. Also, while the calorific power increases with the increase in the parameters of the torrefaction regime, the hygroscopicity and some mechanical properties of the material simultaneously decrease. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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24 pages, 11866 KiB

Open AccessArticle

System Connector “Double Dovetail Tenon”—A Wood–Wood Based Alternative for Connecting CLT-Elements

by Andreas Pomaroli and Anton Kraler

Appl. Sci. 2023, 13(21), 11727; https://doi.org/10.3390/app132111727 - 26 Oct 2023

Viewed by 1396

Abstract

In timber construction, there are still no standardized wall–ceiling system connectors made of wood for cross laminated timber construction (CLT). Based on experimental investigations of the bar-shaped dovetail connections, a wood–wood system connection was developed at the University of Innsbruck. First, the traditional [...] Read more.

In timber construction, there are still no standardized wall–ceiling system connectors made of wood for cross laminated timber construction (CLT). Based on experimental investigations of the bar-shaped dovetail connections, a wood–wood system connection was developed at the University of Innsbruck. First, the traditional dovetail connection for bar-shaped beam connections was investigated. The findings showed the high potential of force transmission in the flank area, especially for beam connections of the same height, where the height of the pre-timber is too small. To date, the load-bearing capacity of the flanks has not been taken into account in the calculation methods. To increase the force transmission paths in the base of the tenon, it was shaped in steps. This led to a load redistribution and thus delayed the failure of the connection. The knowledge gained formed the basis for an independent connecting element that resulted in the so-called “double dovetail”. The connector is a three-dimensional, statically effective double dovetail element. The wood system connector is made of block-glued laminated veneer lumber (LVL) and is manufactured in a CNC-milling process. The results of the tests showed the high performance potential of the LVL system connector, which can play an important role in future timber construction. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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13 pages, 3817 KiB

Open AccessArticle

Handcrafted Reproduction of a 17th Century Bema Door Supported by 3D Digitization and CNC Machining

by Ioannis Barboutis, Vasiliki Kamperidou and George Economidis

Appl. Sci. 2023, 13(21), 11690; https://doi.org/10.3390/app132111690 - 25 Oct 2023

Cited by 2 | Viewed by 1312

Abstract

During the Ottoman period, wood had replaced marble in Orthodox churches. Between the 16th and 19th century, common, unknown craftsmen created wonderful wood-carved ecclesiastical works by hand, though many of them have been partially or completely destroyed, usually without any of their images [...] Read more.

During the Ottoman period, wood had replaced marble in Orthodox churches. Between the 16th and 19th century, common, unknown craftsmen created wonderful wood-carved ecclesiastical works by hand, though many of them have been partially or completely destroyed, usually without any of their images being saved. Advances in technology now make it possible to develop a detailed digital copy of an object of our cultural heritage, creating an unaltered prototype material to be studied by all, while offering in parallel the ease of reproducing precise copies, ensuring even museum quality standards. In the present study, a corresponding attempt to record, scan and then reconstruct a 17th century “Bema Door” (located in the Holy Monastery of Hilandar in Mount Athos) is implemented, presented step-by-step and discussed, in order to highlight the challenges and potential of the applied methods. The process included on-site recording of a 3D digital scan, and then the creation of the Bema door copy, first applying Computerized Numerical Control (CNC) machining and then, with elaborate handwork by experienced wood-carvers who successfully completed the process, imparting the necessary and unique human artistic character. The current work transfers the experience on this reproduction technique applied in a Bema door element, shares significant information and details on tools, materials, process steps, etc., in order to be an inspiration and stimulus for the preservation or reproduction of other cultural heritage monuments of high importance. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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16 pages, 5089 KiB

Open AccessArticle

Applying the Artificial Neural Network and Response Surface Methodology to Optimize the Drilling Process of Plywood

by Bogdan Bedelean, Mihai Ispas and Sergiu Răcășan

Appl. Sci. 2023, 13(20), 11343; https://doi.org/10.3390/app132011343 - 16 Oct 2023

Cited by 3 | Viewed by 997

Abstract

Plywood is a wood-based composite with many applications in construction, shipbuilding, and furniture production. One of the basic plywood processing and mandatory operations is drilling. Up to now, considerable and very diverse thematic research has been recently carried out on drilling, but little [...] Read more.

Plywood is a wood-based composite with many applications in construction, shipbuilding, and furniture production. One of the basic plywood processing and mandatory operations is drilling. Up to now, considerable and very diverse thematic research has been recently carried out on drilling, but little of that deals with modeling of the drilling process of plywood. Therefore, in this work, the artificial neural network modeling technique and response surface methodology were applied to model and optimize the drilling process of plywood. Two artificial neural network models were developed to predict the thrust force and the drilling torque based on drill tip angle, tooth bite, and drill type. The developed ANN models were used to complete the value of responses in the experimental design, which was requested by the response surface methodology. The trust force during the drilling of plywood is significantly influenced by the drill type (helical or flat). The most significant factor that affects the drilling torque during the drilling of plywood is the tooth bite. A helical drill assures a lower minimum thrust force and drilling torque than a flat drill. The proposed method could be used as an optimization tool during the design phase of the furniture manufacturing process. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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12 pages, 3999 KiB

Open AccessArticle

Lightweight Solid Wood Panels Made of Paulownia Plantation Wood

by Marius Cătălin Barbu, Helmut Radauer, Alexander Petutschnigg, Eugenia Mariana Tudor and Markus Kathriner

Appl. Sci. 2023, 13(20), 11234; https://doi.org/10.3390/app132011234 - 12 Oct 2023

Cited by 2 | Viewed by 1827

Abstract

Light Paulownia seamless-edged glued solid wood panels (SWPs), single-layered and three-layered, were analyzed in this study. Both panel types were calibrated at a thickness of 19 mm, a dimension very often in demand on the SWP market, but produced with other wood species [...] Read more.

Light Paulownia seamless-edged glued solid wood panels (SWPs), single-layered and three-layered, were analyzed in this study. Both panel types were calibrated at a thickness of 19 mm, a dimension very often in demand on the SWP market, but produced with other wood species (for example, spruce, pine, larch and fir). The panels were bonded with melamine-urea formaldehyde, polyurethane and polyvinyl acetate resins. The panels were tested for their physical (density) and mechanical (modulus of rupture, modulus of elasticity, compressive shear strength and wood breakage rate) properties. For the single-layered panels, the mechanical and physical properties did not differ significantly and were similar to massive Paulownia wood. For the three-layered panels, the adhesive application of polyurethane influenced positively all SWP properties. Considering the differences in density, these composites failed to achieve the performance of one- and single-layered panels made of spruce. The results of these findings recommend Paulownia SWPs to be used as lightweight and sustainable core materials in sandwich structures for the furniture and packaging industry, sport articles or non-load-bearing constructions. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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11 pages, 1917 KiB

Open AccessArticle

Elemental Compositions of Wood Plastic Pellets Made from Sawdust and Refuse-Derived Fuel (RDF) Waste

by Aujchariya Chotikhun, Rattikal Laosena, Jitralada Kittijaruwattana, Seng Hua Lee, Kanokorn Sae-Ueng, Charoen Nakason, Yutthapong Pianroj and Emilia-Adela Salca

Appl. Sci. 2023, 13(20), 11162; https://doi.org/10.3390/app132011162 - 11 Oct 2023

Cited by 1 | Viewed by 1410

Abstract

The purpose of this research was to investigate the production and properties of wood plastic pellets (WPP) made from rubberwood sawdust and refuse-derived fuel (RDF). WPP samples were tested for chemical and physical properties and compared to standard wood pellets. The results showed [...] Read more.

The purpose of this research was to investigate the production and properties of wood plastic pellets (WPP) made from rubberwood sawdust and refuse-derived fuel (RDF). WPP samples were tested for chemical and physical properties and compared to standard wood pellets. The results showed that when using RDF, the elemental compositions of WPP can affect the content of Zn, Cu, Pb, Cd, Cr, and As. In addition, RDF samples had a higher heating value of 21.19–22.09 MJ/kg. The physical properties of the samples revealed that they had a density of 1175–1286 kg/m³, a mechanical durability of 98%, and a moisture content of 5.38–11.27%. According to the study’s findings, these manufactured mixed pellets have the potential to be beneficial for alternative sustainable green energy as fuels. Moreover, using RDF, which comes from MSW, could help in global warming mitigation. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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26 pages, 10816 KiB

Open AccessArticle

Effects of Solvents Used for Conservation/Restoration Treatments on Damaged Linden Panels of Cultural Heritage Assets

by Anamaria Moraru-Avram, Constantin Ștefan Ionescu and Aurel Lunguleasa

Appl. Sci. 2023, 13(20), 11148; https://doi.org/10.3390/app132011148 - 10 Oct 2023

Viewed by 1404

Abstract

Heritage objects with wooden supports can degrade in inappropriate storage conditions or when microclimate factors contribute to the development of biological attacks. Another issue regarding the deterioration of artifacts is the lack of a full understanding of material properties and their behavior during [...] Read more.

Heritage objects with wooden supports can degrade in inappropriate storage conditions or when microclimate factors contribute to the development of biological attacks. Another issue regarding the deterioration of artifacts is the lack of a full understanding of material properties and their behavior during restoration treatments. In this paper, we note the strengthening treatments of artifacts with severely damaged wood and the various treatments against bio-pests. The influence of solvent on dimensional changes was observed for water, acetone, and white spirit. Acetone was found to cause the greatest swelling and deformation of the treated panels. The present work highlights the importance of choosing not only the correct types of solvents for the solubilization of synthetic resins, as well as those used in conservation-restoration treatments, but also the effects they have on polychrome wood panels that have been degraded by xylophagous insects. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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12 pages, 7702 KiB

Open AccessArticle

Drying Behaviour of Western Hemlock with Schedules Developed for Norway Spruce and Scots Pine

by Ebrahim Hajian, José Couceiro, Lars Hansson and Dick Sandberg

Appl. Sci. 2023, 13(19), 11083; https://doi.org/10.3390/app131911083 - 9 Oct 2023

Viewed by 1272

Abstract

Determining moisture content (MC) distribution during the drying of porous materials such as wood is crucial for developing drying schedules and assessing their suitability to achieve optimised processes. This study aimed to determine the causes of the unique drying behaviour and the well-known [...] Read more.

Determining moisture content (MC) distribution during the drying of porous materials such as wood is crucial for developing drying schedules and assessing their suitability to achieve optimised processes. This study aimed to determine the causes of the unique drying behaviour and the well-known unusual longer drying time of western hemlock compared to other similar softwoods. In situ X-ray computed tomography (CT) was used to study the evolution of MC in timber during the drying process. The drying behaviour of western hemlock (Tsuga heterophylla (Raf.) Sarg.) was compared with Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) from green to oven-dried condition with industry-proposed drying schedules used for steering a custom-made experimental kiln combined with a CT scanner. CT scanning was performed at 30 min intervals during the complete drying period of 30 h, and the CT images were processed to calculate the MC evolution within the specimen. Western hemlock showed a considerably slower capillary-phase drying and did not go into the transition and diffusion phases when a schedule adapted to pine and spruce drying was applied for its drying. CT images and MC gradient calculations showed a lower drying rate and severe non-uniformity in MC distribution, which could be due to the effect of higher green MC and the presence of wet pockets. Furthermore, the evaporation front at the first 5 h of drying receded faster into the hemlock specimen, and as drying proceeded, it slowed down compared to other specimens. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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9 pages, 8433 KiB

Open AccessArticle

Drying Behaviour of 50 mm Thick Turkey Oak Lumber

by Iulia-Teodora Deaconu, Sergiu-Valeriu Georgescu and Mihaela Campean

Appl. Sci. 2023, 13(19), 10676; https://doi.org/10.3390/app131910676 - 26 Sep 2023

Viewed by 891

Abstract

Turkey oak lumber is difficult to dry, being prone to cracks even at low temperatures. The main objective of the research was to test different drying conditions in order to establish whether air-drying or kiln-drying from a green state was more suitable; if [...] Read more.

Turkey oak lumber is difficult to dry, being prone to cracks even at low temperatures. The main objective of the research was to test different drying conditions in order to establish whether air-drying or kiln-drying from a green state was more suitable; if the lumber width had an influence on the drying quality; if prior steaming had a positive effect upon the kiln-drying time and quality; if end cracks could be avoided by protecting the board ends; and what the most appropriate kiln-drying conditions were, with conventional drying. The research results recommend kiln-drying as a better alternative than air-drying in terms of both time and quality, but very mild conditions must be applied. Wide lumber parts cracked both when air-dried and when kiln-dried. All defect-free lumber parts dried accurately, with no deterioration. Steaming had a positive effect upon the drying quality; no steamed part cracked. The end protection of the boards was efficient only in the case of kiln-drying. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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22 pages, 5703 KiB

Open AccessArticle

Differences and Similarities between the Wood of Three Low-Density and Homogenous Species: Linden, Balsa, and Paulownia

by Anamaria Avram, Aurel Lunguleasa, Cosmin Spirchez and Constantin Stefan Ionescu

Appl. Sci. 2023, 13(18), 10209; https://doi.org/10.3390/app131810209 - 11 Sep 2023

Viewed by 1222

Abstract

The use of woods with a low density and good structural uniformity has intensified in recent decades, paving new ways for their superior valorization. This research study aimed to examine the wood of three deciduous wood species with low densities and great uniformity [...] Read more.

The use of woods with a low density and good structural uniformity has intensified in recent decades, paving new ways for their superior valorization. This research study aimed to examine the wood of three deciduous wood species with low densities and great uniformity of structure, namely linden wood, with an oven-dried density of 461 kg/m³, paulownia wood, with an oven-dried density of 304 kg/m³, and balsa wood, with an oven-dried density of 118 kg/m³. The physical and mechanical properties of these species were studied using various methodologies. The obtained results show that, although they have significant differences in terms of densities and mechanical characteristics, the coloristic properties of the three analyzed species obtained using the CIELab are almost similar. As a general conclusion, based on all the properties found in this research, it can be concluded that paulownia wood is more appropriate than linden or balsa for use, being able to replace linden in its uses. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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15 pages, 26610 KiB

Open AccessArticle

Wood Utilization in Windmill Mechanisms on Sikinos Island (Greece)

by Evangelia Agnantopoulou, Ioannis Barboutis and Vasiliki Kamperidou

Appl. Sci. 2023, 13(16), 9216; https://doi.org/10.3390/app13169216 - 14 Aug 2023

Cited by 2 | Viewed by 1212

Abstract

Windmills constitute a valuable part of cultural heritage, especially in Greece, as unique structures of popular architecture and know-how of the pre-industrial era. Their wooden mechanisms were of exceptional constructional ingenuity, with the Mediterranean ones bearing a vertical wing and a rotating roof [...] Read more.

Windmills constitute a valuable part of cultural heritage, especially in Greece, as unique structures of popular architecture and know-how of the pre-industrial era. Their wooden mechanisms were of exceptional constructional ingenuity, with the Mediterranean ones bearing a vertical wing and a rotating roof (“trula”), with a manual torsion mechanism that allowed for operation in all wind directions. Sikinos is a small Aegean island characterized by rich landscapes, which do not have wood-producing forests, but only sparse Juniperus phoenicea shrub land mixed with evergreen hardwood species and the presence of numerous sclerophyllus vegetation species (maquis). Three abandoned windmills are still preserved on the island today, but only two of them appear to have their wooden mechanisms left. In the one windmill mechanism examined, it was found that different wood species were used to manufacture its individual parts. Oak wood was used in most of the large elements, with the exception of the sprattle beam (“zigos”), which is made of fir wood. The local juniper was not used in any crucial part of the mechanism, though it was used only as a structural material on the first floor (“anogio”) flooring, along with large-diameter olive trunks. The findings of this study highlighted the thorough knowledge of the properties of various wood species and the effective use of simple tools toward the construction of functional and effective windmill mechanisms. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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Review

Jump to: Editorial, Research

21 pages, 994 KiB

Open AccessReview

Utilization Potential of Tree-of-Heaven Species Biomass—A Review

by Paschalina Terzopoulou, Vasiliki Kamperidou and Ioannis Barboutis

Appl. Sci. 2023, 13(16), 9185; https://doi.org/10.3390/app13169185 - 12 Aug 2023

Cited by 6 | Viewed by 2139

Abstract

Climate change and the subsequent increase in global mean air temperature already present a significant impact on forest vegetation. Especially in the near future, several forest species are expected to be in danger of extinction or compelled to migrate to colder regions. Some [...] Read more.

Climate change and the subsequent increase in global mean air temperature already present a significant impact on forest vegetation. Especially in the near future, several forest species are expected to be in danger of extinction or compelled to migrate to colder regions. Some common species will be replaced by highly climate-tolerant species, primarily exotic plants, among others. The tree of Ailanthus, or “tree-of-heaven”, as it is widely known, constitutes a rapidly growing plant, considered to be native to parts of China, while since the middle of the 18th century, it gradually spread to Europe and North America. This species demonstrates a preference for warmer, drier environments, although it can also survive in a variety of habitats and endure pollution of urban areas. It is a species with several uses, such as for animal feed, fuel, timber, pharmaceutical applications, etc., while its suitability for specialized applications of high-added-value is constantly being investigated. Its wood has a desirable appearance and characteristics that are comparable to those of other hardwood species of similar densities/weight. This article discusses some of the most important characteristics of Ailanthus wood and presents a comprehensive and constructive review of the chemistry, pharmacology, traditional and innovative uses, quality control, biological resistance, potential utilization in bioenergy and biofuels and wood products (e.g., wood-based panels, other advanced structure materials, etc.), use challenges and limitations, in order to contribute to the utilization potential assessment of this species biomass. Full article

(This article belongs to the Special Issue International Conference Wood Science and Engineering in the Third Millennium - ICWSE 2023)

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