Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
6.6
5.0
Journals
Polymers
Special Issues
New Challenges in Wood and Wood-Based Materials II
share announcement

New Challenges in Wood and Wood-Based Materials II

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Biomacromolecules, Biobased and Biodegradable Polymers".

Deadline for manuscript submissions: closed (31 July 2022) | Viewed by 32379

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

Special Issue Editors

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
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
Prof. Dr. Ivan Kubovský

E-Mail Website
Guest Editor
Faculty of Wood Sciences and Technology, Technical University in Zvolen, 960 01 Zvolen, Slovakia
Interests: material properties; laser irradiation; physics; electrical engineering; colour; wood sciences
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Wood is a natural material, available in large quantities and is easy to produce, making it the perfect material to consider for the circular economy. Its importance has been dramatically increased in recent years. This increase is accompanied by the development of new research methods which open new possibilities in the areas related to wood and wood products in the process of their production, processing and final use. The main topics of the Special Issue: Knowledge of quality of wood and other lignocelluloses materials in relation to processes of their effective utilization and processing for more efficient processing.Adopting some of the techniques and research around using wood for environmentally friendly composite production and the positive impact on the environment.

Wood interaction with solid substances and with different mechanical load, chemical and other substances and different forms of energy.Surface modification of wood and wood composites.

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

Manuscript Submission Information

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

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

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • wood and wood based materials
  • wood composite materials
  • adhesives for composites
  • wood processing and mechanical modification
  • surface modification of wood and wood composites
  • chemical and thermal modification of wood and wood composites

Related Special Issue

Published Papers (14 papers)

Download All Papers
Order results
Result details
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:

Editorial

Jump to: Research

7 pages, 258 KiB  
Editorial
New Challenges in Wood and Wood-Based Materials II
by Lubos Kristak, Roman Réh and Ivan Kubovský
Polymers 2023, 15(6), 1409; https://0-doi-org.brum.beds.ac.uk/10.3390/polym15061409 - 12 Mar 2023
Cited by 1 | Viewed by 1518
Abstract
Wood is a natural material that is available in large quantities and is easy to produce, making it the perfect material to consider for the circular economy [...] Full article
(This article belongs to the Special Issue New Challenges in Wood and Wood-Based Materials II)

Research

Jump to: Editorial

20 pages, 10967 KiB  
Article
Compressive Strength Properties Perpendicular to the Grain of Hollow Glue-Laminated Timber Elements
by Nikola Perković, Jure Barbalić, Vlatka Rajčić and Ivan Duvnjak
Polymers 2022, 14(16), 3403; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14163403 - 19 Aug 2022
Cited by 1 | Viewed by 3375
Abstract
Timber is one of the fundamental materials of human civilization, it is very useful and ecologically acceptable in its natural environment, and it fits very well with modern trends in green construction. The paper presents innovative hollow glued laminated (GL) timber elements intended [...] Read more.
Timber is one of the fundamental materials of human civilization, it is very useful and ecologically acceptable in its natural environment, and it fits very well with modern trends in green construction. The paper presents innovative hollow glued laminated (GL) timber elements intended for log-house construction. Due to the lack of data on the behavior of the hollow timber section in compression perpendicular to the grain, the paper presented involves testing the compression strength of elliptical hollow cross-section glue-laminated timber specimens made of softwood and hardwood, as well as full cross-section glue-laminated softwood timber specimens. The experimental research was carried out on a total of 120 specimens. With the maximal reduction of 26% compared to the full cross-section, regardless of the type of wood and direction of load, the compression strength perpendicular to the grain of hollow specimens decreases by about 55% compared to the full cross-section, with the coefficient kc,90 equal to 1.0. For load actions at the edge and the middle of the element, kc,90 factors were obtained with a value closer to those obtained for full cross-section, which indicates the same phenomenology, regardless of cross-sectional weakening. At the same time, the factors in the stronger axis are lower by about 10%, and in the weaker axis by about 30% compared to those prescribed by the Eurocode. Experimental research was confirmed by FEM analysis. Comparative finite element analysis was performed in order to provide recommendations for future research and, consequently, to determine the optimal cross-section form of the hollow GL timber element. By removing the holes in the central part of the cross-section, the stress is reduced. The distance of the holes from the edges defines the local cracking. Finally, if the holes are present only in the central part of the element, the behavior of the element is more favorable. Full article
(This article belongs to the Special Issue New Challenges in Wood and Wood-Based Materials II)
►▼ Show Figures

Figure 1

19 pages, 6066 KiB  
Article
Withdrawal Performance of Nails and Screws in Cross-Laminated Timber (CLT) Made of Poplar (Populus alba) and Fir (Abies alba)
by Farshid Abdoli, Maria Rashidi, Akbar Rostampour-Haftkhani, Mohammad Layeghi and Ghanbar Ebrahimi
Polymers 2022, 14(15), 3129; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14153129 - 31 Jul 2022
Cited by 7 | Viewed by 1959
Abstract
Cross-laminated timber (CLT) can be used as an element in various parts of timber structures, such as bridges. Fast-growing hardwood species, like poplar, are useful in regions where there is a lack of wood resources. In this study, the withdrawal resistance of nine [...] Read more.
Cross-laminated timber (CLT) can be used as an element in various parts of timber structures, such as bridges. Fast-growing hardwood species, like poplar, are useful in regions where there is a lack of wood resources. In this study, the withdrawal resistance of nine types of conventional fasteners (stainless-steel nails, concrete nails and screws, drywall screws, three types of partially and fully threaded wood screws, and two types of lag screws), with three loading directions (parallel to the grain, perpendicular to the surface, and tangential), and two layer arrangements (0-90-0° and 0-45-0°) in 3-ply CLTs made of poplar as a fast-growing species and fir as a common species in manufacturing of CLT was investigated. Lag screws (10 mm) displayed the highest withdrawal resistance (145.77 N), whereas steel nails had the lowest (13.13 N), according to the main effect analysis. Furthermore, fasteners loaded perpendicular to the grain (perpendicular to the surface and tangential) had higher withdrawal resistance than those loaded parallel to the grain (edge). In terms of the layer arrangement, fasteners in CLTs manufactured from poplar wood (0-45-0°) had the greatest withdrawal resistance, followed by CLTs manufactured from poplar wood in the (0-90-0°) arrangement, and finally, those made from fir wood in the (0-90-0°) arrangement. The fastener type had the most significant impact on the withdrawal resistance, so changing the fastener type from nails to screws increased it by about 5–11 times, which is consistent with other studies. The results showed that poplar, a fast-growth species, is a proper wood for manufacturing CLTs in terms of fastener withdrawal performance. Full article
(This article belongs to the Special Issue New Challenges in Wood and Wood-Based Materials II)
►▼ Show Figures

Figure 1

14 pages, 2606 KiB  
Article
Thermal Modification of Spruce and Maple Wood for Special Wood Products
by Anna Danihelová, Zuzana Vidholdová, Tomáš Gergeľ, Lucia Spišiaková Kružlicová and Michal Pástor
Polymers 2022, 14(14), 2813; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14142813 - 10 Jul 2022
Cited by 5 | Viewed by 1593
Abstract
This article presents a proposal of thermal modification of Norway spruce and sycamore maple for special wood products, mainly for musical instruments. Selected physical and acoustical characteristics (PACHs), including the density (ρ), dynamic modulus of elasticity along the wood grain ( [...] Read more.
This article presents a proposal of thermal modification of Norway spruce and sycamore maple for special wood products, mainly for musical instruments. Selected physical and acoustical characteristics (PACHs), including the density (ρ), dynamic modulus of elasticity along the wood grain (EL), specific modulus (Esp), speed of sound along the wood grain (cL), resonant frequency (fr) and acoustic constant (A), logarithmic decrement (ϑ), loss coefficient (η), acoustic conversion efficiency (ACE), sound quality factor (Q), and the timbre of sound, were evaluated. These two wood species were chosen regarding their use in the production or repair of musical instruments. For the thermal modification, a similar process to the ThermoWood process was chosen. Thermal modification was performed at the temperatures 135 °C, 160 °C and 185 °C. The resonant dynamic method was used to obtain the PACHs. Fast Fourier transform (FFT) was used to analyze the sound produced. The changes in the observed wood properties depended on the treatment temperature. Based on our results of all properties, the different temperature modified wood could find uses in the making of musical instruments or where the specific values of these wood characteristics are required. The mild thermal modification resulted in a decrease in mass, density, and increased speed of sound and dynamic modulus of elasticity at all temperatures of modification. The thermally modified wood showed higher sound radiation and lower loss coefficients than unmodified wood. The modification also influenced the timbre of sound of both wood species. Full article
(This article belongs to the Special Issue New Challenges in Wood and Wood-Based Materials II)
►▼ Show Figures

Graphical abstract

14 pages, 2326 KiB  
Article
Quebracho Tannin Bio-Based Adhesives for Plywood
by Johannes Jorda, Emanuele Cesprini, Marius-Cătălin Barbu, Gianluca Tondi, Michela Zanetti and Pavel Král
Polymers 2022, 14(11), 2257; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14112257 - 31 May 2022
Cited by 7 | Viewed by 2339
Abstract
Wood-based products are traditionally bonded with synthetic adhesives. Resources availability and ecological concerns have drawn attention to bio-based sources. The use of tannin-based adhesives for engineered wood products has been known for decades, however, these formulations were hardly used for the gluing of [...] Read more.
Wood-based products are traditionally bonded with synthetic adhesives. Resources availability and ecological concerns have drawn attention to bio-based sources. The use of tannin-based adhesives for engineered wood products has been known for decades, however, these formulations were hardly used for the gluing of solid wood because their rigidity involved low performance. In this work, a completely bio-based formulation consisting of Quebracho (Schinopsis balancae) extract and furfural is characterized in terms of viscosity, gel time, and FT-IR spectroscopy. Further, the usability as an adhesive for beech (Fagus sylvatica) plywood with regard to press parameters (time and temperature) and its influence on physical (density and thickness) and mechanical properties (modulus of elasticity, modulus of rupture and tensile shear strength) were determined. These polyphenolic adhesives presented non-Newtonian behavior but still good spreading at room temperature as well as evident signs of crosslinking when exposed to 100 °C. Within the press temperature, a range of 125 °C to 140 °C gained suitable results with regard to mechanical properties. The modulus of elasticity of five layered 10 mm beech plywood ranged between 9600 N/mm2 and 11,600 N/mm2, respectively, with 66 N/mm2 to 100 N/mm2 for the modulus of rupture. The dry state tensile shear strength of ~2.2 N/mm2 matched with other tannin-based formulations, but showed delamination after 24 h of water storage. The proposed quebracho tannin-furfural formulation can be a bio-based alternative adhesive for industrial applicability for special plywood products in a dry environment, and it offers new possibilities in terms of recyclability. Full article
(This article belongs to the Special Issue New Challenges in Wood and Wood-Based Materials II)
►▼ Show Figures

Figure 1

12 pages, 4197 KiB  
Article
Effect of Sunlight on the Change in Color of Unsteamed and Steamed Beech Wood with Water Steam
by Michal Dudiak, Ladislav Dzurenda and Viera Kučerová
Polymers 2022, 14(9), 1697; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14091697 - 21 Apr 2022
Cited by 8 | Viewed by 1879
Abstract
This paper presents the differences in the color changes of unsteamed and steamed beech wood (Fagus sylvatica L.) caused by long-term exposure to sunlight on the surface of wood in interiors for 36 months. The light white-gray color of the yellow tinge [...] Read more.
This paper presents the differences in the color changes of unsteamed and steamed beech wood (Fagus sylvatica L.) caused by long-term exposure to sunlight on the surface of wood in interiors for 36 months. The light white-gray color of the yellow tinge of native beech wood darkened under the influence of sunlight, and the wood took on a pale brown color of yellow tinge. The degree of darkening and browning is quantified by the value of the total color difference ∆E* = 13.0. The deep brown-red color of steamed beech under the influence of sunlight during the exposure brightened, and the surface of the wood took on a pale brown hue. The degree of lightening of the color of steamed beech wood in the color space CIE L*a*b* is quantified by the value of the total color difference ∆E* = 7.1. A comparison of the color changes of unsteamed and steamed beech wood through the total color difference ∆E* due to daylight shows that the surface of steamed beech wood shows 52.2% smaller changes than unsteamed beech wood. The lower value of the total color difference of steamed beech wood indicates the fact that steaming of beech wood with saturated water steam has a positive effect on the color stability and partial resistance of steamed beech wood to the initiation of photochemical reactions induced by UV–VIS wavelengths of solar radiation. Spectra ATR-FTIR analyses declare the influence of UV–VIS components of solar radiation on unsteamed and steamed beech wood and confirm the higher color stability of steamed beech wood. Full article
(This article belongs to the Special Issue New Challenges in Wood and Wood-Based Materials II)
►▼ Show Figures

Figure 1

14 pages, 4320 KiB  
Article
Experimental Study of the Influence of Selected Factors on the Particle Board Ignition by Radiant Heat Flux
by Ivana Tureková, Martina Ivanovičová, Jozef Harangózo, Stanislava Gašpercová and Iveta Marková
Polymers 2022, 14(9), 1648; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14091648 - 19 Apr 2022
Cited by 5 | Viewed by 1881
Abstract
Particleboards are used in the manufacturing of furniture and are often part of the interior of buildings. In the event of a fire, particleboards are a substantial part of the fuel in many building fires. The aim of the article is to monitor [...] Read more.
Particleboards are used in the manufacturing of furniture and are often part of the interior of buildings. In the event of a fire, particleboards are a substantial part of the fuel in many building fires. The aim of the article is to monitor the effect of radiant heat on the surface of particle board according to the modified procedure ISO 5657: 1997. The significance of the influence of heat flux density and particle board properties on its thermal resistance (time to ignition) was monitored. Experimental samples were used particle board without surface treatment, with thicknesses of 12, 15, and 18 mm. The samples were exposed to a heat flux from 40 to 50 kW·m−2. The experimental results are the initiation characteristics such as of the ignition temperature and the weight loss. The determined factors influencing the time to ignition and weight loss were the thickness and density of the plate material, the density of the radiant heat flux and the distance of the particle board from the radiant source (20, 40, and 60 mm). The obtained results show a significant dependence of the time to ignition on the thickness of the sample and on the heat flux density. The weight loss is significantly dependent on the thickness of the particle board. Monitoring the influence of time to ignition from sample distance confirmed a statistically significant dependence. As the distance of the sample from the source increased, the time to ignition decreased linearly. As the distance of the sample from the source increased, the time to ignition increased. Full article
(This article belongs to the Special Issue New Challenges in Wood and Wood-Based Materials II)
►▼ Show Figures

Figure 1

14 pages, 6300 KiB  
Article
The Effect of Openings’ Size and Location on Selected Dynamical Properties of Typical Wood Frame Walls
by Marcin Szczepanski, Ahmed Manguri, Najmadeen Saeed and Daniel Chuchala
Polymers 2022, 14(3), 497; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14030497 - 26 Jan 2022
Cited by 2 | Viewed by 2188
Abstract
The wooden frame constructions are now popular in many developed countries of the world. Many of these locations where such buildings are constructed are exposed to seismic and other shocks which are generated by human activities. This paper discusses the effect of the [...] Read more.
The wooden frame constructions are now popular in many developed countries of the world. Many of these locations where such buildings are constructed are exposed to seismic and other shocks which are generated by human activities. This paper discusses the effect of the size and location of openings in the wooden frame walls under dynamic loadings. Natural frequencies of such frames with and without openings have been determined. Three 14 m high walls with different widths, including 3, 6, and 12 m, have been considered. Dynamic analysis has been made using finite element method structural analysis software Dlubal RFEM 5.17. The results show that the effect of the size and location of the openings on the natural frequency is significant. Numerically speaking, the relative change of the natural frequencies of a wall without and with an opening in a specific place could be up to 30%. In addition, the change of the natural frequency for the location of the openings is more sensitive than that to the sizes. Furthermore, the appropriate sizes and locations of openings of the wooden frame walls have been suggested. The appropriate size and place were found to be small openings in the top of the walls. Full article
(This article belongs to the Special Issue New Challenges in Wood and Wood-Based Materials II)
►▼ Show Figures

Graphical abstract

10 pages, 3227 KiB  
Article
Influence of UV Radiation on the Color Change of the Surface of Steamed Maple Wood with Saturated Water Steam
by Ladislav Dzurenda, Michal Dudiak and Eva Výbohová
Polymers 2022, 14(1), 217; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14010217 - 05 Jan 2022
Cited by 12 | Viewed by 2612
Abstract
The wood of maple (Acer Pseudopatanus L.) was steamed with a saturated steam-air mixture at a temperature of t = 95 °C or saturated steam at t = 115 °C and t = 135 °C, in order to give a pale pink-brown, [...] Read more.
The wood of maple (Acer Pseudopatanus L.) was steamed with a saturated steam-air mixture at a temperature of t = 95 °C or saturated steam at t = 115 °C and t = 135 °C, in order to give a pale pink-brown, pale brown, and brown-red color. Subsequently, samples of unsteamed and steamed maple wood were irradiated with a UV lamp in a Xenotest Q-SUN Xe-3-H after drying, in order to test the color stability of steamed maple wood. The color change of the wood surface was evaluated by means of measured values on the coordinates of the color space CIE L* a* b*. The results show that the surface of unsteamed maple wood changes color markedly under the influence of UV radiation than the surface of steamed maple wood. The greater the darkening and browning color of the maple wood by steaming, the smaller the changes in the values at the coordinates L*, a*, b* of the steamed maple wood caused by UV radiation. The positive effect of steaming on UV resistance is evidenced by the decrease in the overall color difference ∆E*. While the value of the total color diffusion of unsteamed maple wood induced by UV radiation is ∆E* = 18.5, for maple wood steamed with a saturated steam-air mixture at temperature t = 95 °C the ∆E* decreases to 12.6, for steamed maple wood with saturated water steam with temperature t = 115 °C the ∆E* decreases to 10.4, and for saturated water steam with temperature t = 135 °C the ∆E* decreases to 7.2. Differential ATR-FTIR spectra declare the effect of UV radiation on unsteamed and steamed maple wood and confirm the higher color stability of steamed maple wood. Full article
(This article belongs to the Special Issue New Challenges in Wood and Wood-Based Materials II)
►▼ Show Figures

Figure 1

14 pages, 2252 KiB  
Article
Enzymatic Functionalization of Wood as an Antifouling Strategy against the Marine Bacterium Cobetia marina
by Daniel Filgueira, Cristian Bolaño, Susana Gouveia and Diego Moldes
Polymers 2021, 13(21), 3795; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13213795 - 02 Nov 2021
Cited by 5 | Viewed by 1466
Abstract
The protection of wood in marine environments is a major challenge due to the high sensitivity of wood to both water and marine microorganisms. Besides, the environmental regulations are pushing the industry to develop novel effective and environmentally friendly treatments to protect wood [...] Read more.
The protection of wood in marine environments is a major challenge due to the high sensitivity of wood to both water and marine microorganisms. Besides, the environmental regulations are pushing the industry to develop novel effective and environmentally friendly treatments to protect wood in marine environments. The present study focused on the development of a new green methodology based on the laccase-assisted grafting of lauryl gallate (LG) onto wood to improve its marine antifouling properties. Initially, the enzymatic treatment conditions (laccase dose, time of reaction, LG concentration) and the effect of the wood specie (beech, pine, and eucalyptus) were assessed by water contact angle (WCA) measurements. The surface properties of the enzymatically modified wood veneers were assessed by X-ray photoelectron spectroscopy (XPS), Fourier transform-infrared spectroscopy (FTIR). Antifouling properties of the functionalized wood veneers against marine bacterium Cobetia marina were studied by scanning electron microscopy (SEM) and protein measurements. XPS and FTIR analysis suggested the stable grafting of LG onto the surface of wood veneers after laccase-assisted treatment. WCA measurements showed that the hydrophobicity of the wood veneers significantly increased after the enzymatic treatment. Protein measurements and SEM pictures showed that enzymatically-hydrophobized wood veneers modified the pattern of bacterial attachment and remarkably reduced the bacterium colonization. Thus, the results observed in the present study confirmed the potential efficiency of laccase-assisted treatments to improve the marine antifouling properties of wood. Full article
(This article belongs to the Special Issue New Challenges in Wood and Wood-Based Materials II)
►▼ Show Figures

Graphical abstract

15 pages, 21240 KiB  
Article
Influence of Adhesive Systems on the Mechanical and Physical Properties of Flax Fiber Reinforced Beech Plywood
by Johannes Jorda, Günther Kain, Marius-Catalin Barbu, Alexander Petutschnigg and Pavel Král
Polymers 2021, 13(18), 3086; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13183086 - 13 Sep 2021
Cited by 13 | Viewed by 2298
Abstract
In order to improve the acceptance of broader industrial application of flax fiber reinforced beech (Fagus sylvatica L.) plywood, five different industrial applicated adhesive systems were tested. Epoxy resin, urea-formaldehyde, melamine-urea formaldehyde, isocyanate MDI prepolymer, and polyurethane displayed a divergent picture in [...] Read more.
In order to improve the acceptance of broader industrial application of flax fiber reinforced beech (Fagus sylvatica L.) plywood, five different industrial applicated adhesive systems were tested. Epoxy resin, urea-formaldehyde, melamine-urea formaldehyde, isocyanate MDI prepolymer, and polyurethane displayed a divergent picture in improving the mechanical properties—modulus of elasticity, modulus of rupture, tensile strength, shear strength and screw withdrawal resistance—of flax fiber-reinforced plywood. Epoxy resin is well suited for flax fiber reinforcement, whereas urea-formaldehyde, melamine urea-formaldehyde, and isocyanate prepolymer improved modulus of elasticity, modulus of rupture, shear strength, and screw withdrawal resistance, but lowered tensile strength. Polyurethane lowered the mechanical properties of flax fiber reinforced plywood. Flax fiber reinforced epoxy resin bonded plywood exceeded glass fiber reinforced plywood in terms of shear strength, modulus of elasticity, and modulus of rupture. Full article
(This article belongs to the Special Issue New Challenges in Wood and Wood-Based Materials II)
►▼ Show Figures

Figure 1

13 pages, 2800 KiB  
Article
Flammability Characteristics of Thermally Modified Meranti Wood Treated with Natural and Synthetic Fire Retardants
by Milan Gaff, Hana Čekovská, Jiří Bouček, Danica Kačíková, Ivan Kubovský, Tereza Tribulová, Lingfeng Zhang, Salvio Marino and František Kačík
Polymers 2021, 13(13), 2160; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13132160 - 30 Jun 2021
Cited by 7 | Viewed by 2663
Abstract
This paper deals with the effect of synthetic and natural flame retardants on flammability characteristics and chemical changes in thermally treated meranti wood (Shorea spp.). The basic chemical composition (extractives, lignin, holocellulose, cellulose, and hemicelluloses) was evaluated to clarify the relationships of [...] Read more.
This paper deals with the effect of synthetic and natural flame retardants on flammability characteristics and chemical changes in thermally treated meranti wood (Shorea spp.). The basic chemical composition (extractives, lignin, holocellulose, cellulose, and hemicelluloses) was evaluated to clarify the relationships of temperature modifications (160 °C, 180 °C, and 210 °C) and incineration for 600 s. Weight loss, burning speed, the maximum burning rate, and the time to reach the maximum burning rate were evaluated. Relationships between flammable properties and chemical changes in thermally modified wood were evaluated with the Spearman correlation. The thermal modification did not confirm a positive contribution to the flammability and combustion properties of meranti wood. The effect of the synthetic retardant on all combustion properties was significantly higher compared to that of the natural retardant. Full article
(This article belongs to the Special Issue New Challenges in Wood and Wood-Based Materials II)
►▼ Show Figures

Figure 1

13 pages, 3944 KiB  
Article
Effect of UV Radiation on Optical Properties and Hardness of Transparent Wood
by Igor Wachter, Tomáš Štefko, Peter Rantuch, Jozef Martinka and Alica Pastierová
Polymers 2021, 13(13), 2067; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13132067 - 23 Jun 2021
Cited by 23 | Viewed by 3488
Abstract
Optically transparent wood is a type of composite material, combining wood as a renewable resource with the optical and mechanical properties of synthetic polymers. During this study, the effect of monochromatic UV-C (λ—250 nm) radiation on transparent wood was evaluated. Samples of basswood [...] Read more.
Optically transparent wood is a type of composite material, combining wood as a renewable resource with the optical and mechanical properties of synthetic polymers. During this study, the effect of monochromatic UV-C (λ—250 nm) radiation on transparent wood was evaluated. Samples of basswood were treated using a lignin modification method, to preserve most of the lignin, and subsequently impregnated with refractive-index-matched types of acrylic polymers (methyl methacrylate, 2-hydroxyethyl methacrylate). Optical (transmittance, colour) and mechanical (shore D hardness) properties were measured to describe the degradation process over 35 days. The transmittance of the samples was significantly decreased during the first seven days (12% EMA, 15% MMA). The average lightness of both materials decreased by 10% (EMA) and 17% (MMA), and the colour shifted towards a red and yellow area of CIE L*a*b* space coordinates. The influence of UV-C radiation on the hardness of the samples was statistically insignificant (W+MMA 84.98 ± 2.05; W+EMA 84.89 ± 2.46), therefore the hardness mainly depends on the hardness of used acrylic polymer. The obtained results can be used to assess the effect of disinfection of transparent wood surfaces with UV-C radiation (e.g., due to inactivation of SARS-CoV-2 virus) on the change of its aesthetic and mechanical properties. Full article
(This article belongs to the Special Issue New Challenges in Wood and Wood-Based Materials II)
►▼ Show Figures

Figure 1

10 pages, 721 KiB  
Article
Effect of Natural Aging on Oak Wood Fire Resistance
by Martin Zachar, Iveta Čabalová, Danica Kačíková and Tereza Jurczyková
Polymers 2021, 13(13), 2059; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13132059 - 23 Jun 2021
Cited by 9 | Viewed by 1825
Abstract
The paper deals with the assessment of the age of oak wood (0, 10, 40, 80 and 120 years) on its fire resistance. Chemical composition of wood (extractives, cellulose, holocellulose, lignin) was determined by wet chemistry methods and elementary analysis was performed according [...] Read more.
The paper deals with the assessment of the age of oak wood (0, 10, 40, 80 and 120 years) on its fire resistance. Chemical composition of wood (extractives, cellulose, holocellulose, lignin) was determined by wet chemistry methods and elementary analysis was performed according to ISO standards. From the fire-technical properties, the flame ignition and the spontaneous ignition temperature (including calculated activation energy) and mass burning rate were evaluated. The lignin content does not change, the content of extractives and cellulose is higher and the content of holocellulose decreases with the higher age of wood. The elementary analysis shows the lowest proportion content of nitrogen, sulfur, phosphor and the highest content of carbon in the oldest wood. Values of flame ignition and spontaneous ignition temperature for individual samples were very similar. The activation energy ranged from 42.4 kJ·mol−1 (120-year-old) to 50.7 kJ·mol−1 (40-year-old), and the burning rate varied from 0.2992%·s−1 (80-year-old) to 0.4965%·s−1 (10-year-old). The difference among the values of spontaneous ignition activation energy is clear evidence of higher resistance to initiation of older wood (40- and 80-year-old) in comparison with the younger oak wood (0- and 10-year-old). The oldest sample is the least thermally resistant due to the different chemical composition compared to the younger wood. Full article
(This article belongs to the Special Issue New Challenges in Wood and Wood-Based Materials II)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-14
Back to TopTop