Chemical modification as a non-biocidal treatment is an effective method to improve physical and biological properties of wood. Poplar is a fast growing species but has poor dimensional stability and ...durability in addition to low mechanical properties. Low molecular weight Dimethylol dihydroxyethyleneurea (mDMDHEU) was used to improve the properties of poplar mainly dimensional stability and decay resistance. Results indicated high anti-swelling efficiency (ASE), but low variation between both concentrations of mDMDHEU. Tangential swelling was greatly reduced by mDMDHEU treatment during the water immersion period. Untreated poplar samples were severely decayed as compared to modified samples. Modified samples showed lower bending strength unlike to compression strength. Ester peak at 1720 cm-1 revealed chemical reaction between chemical reagent and wood cell wall components. Control samples exhibited considerably higher thermal degradation when compared to the samples modified with mDMDHEU.
Kemijska modifikacija kao postupak bez biocida učinkovita je metoda za poboljšanje fizičkih i bioloških svojstava drva. Topolovina je drvo vrste koja brzo raste, ali ima slabu dimenzijsku stabilnost i prirodnu trajnost te slaba mehanička svojstva. Za poboljšanje svojstava topolovine, prije svega dimenzijske stabilnosti i otpornosti na propadanje, upotrijebljena je dimetilol dihidroksietilenurea male molekularne mase (mDMDHEU). Rezultati su pokazali visoku učinkovitost kemijske modifikacije u smislu sprječavanja bubrenja topolovine (ASE), ali s malom varijacijom među dvjema primijenjenim koncentracijama mDMDHEU-a. Tangencijalno bubrenje uzoraka topolovine tijekom uranjanja u vodu uvelike je smanjeno mDMDHEU modifikacijom. Nemodificirani uzorci topolovine bili su vrlo truli u usporedbi s modificiranima. Modificirani su uzorci, pak, pokazali manju čvrstoću na savijanje u usporedbi s tlačnom čvrstoćom. Vrh vrpce na 1720 cm-1 otkrio je kemijsku reakciju između kemijskog reagensa i spojeva u staničnoj stijenci drva. Na kontrolnim je uzorcima nastala znatno veća toplinska degradacija nego na uzorcima modificiranima mDMDHEU-om.
With the increasing demands on sustainability in the material science and engineering landscape, the use of wood, a renewable and biodegradable material, for new material development has drawn ...increasing attentions in the materials science community. To promote the development of new wood-based materials, it is critical to understanding not only wood's hierarchical structure from molecule to macroscale level, but also the interactions of wood with other materials and chemicals upon modification and functionalization. In this review, we discuss the recent advances in the Raman imaging technique, a new approach that combines spectroscopy and microscopy, in wood characterization and structural evolution monitoring during functionalization. We introduce the principles of Raman spectroscopy and common Raman instrumentations. We survey the use of traditional Raman spectroscopy for lignocellulosic material characterizations including cellulose crystallinity determination, holocellulose discrimination, and lignin substructure evaluation. We briefly review the recent studies on wood property enhancement and functional wood-based material development through wood modification including thermal treatment, acetylation, furfurylation, methacrylation, delignification. Subsequently, we highlight the use of the Raman imaging for visualization, spatial and temporal distribution of wood cell wall structure, as well as the microstructure evolution upon functionalization. Finally, we discuss the future prospects of the field.
Wood's vulnerability to combustion compromises its structural integrity during fire incidents, primarily due to a decrease in effective cross-section area. This study investigates the efficacy of ...impregnation Chinese fir lumbers with a 30 % concentration of borate-containing phenol–formaldehyde resin, coupled with a 30 % compression treatment, employed as exposed side laminas for glulam columns. Full-scale glulam columns underwent one-sided fire exposure to assess the impact of the modified laminas. Results reveal a significant increase in column ignition time by 55–195 s, due to the combined treatment. The charring rate of columns containing a single modified lamina in the fire-side zone decreased from 0.733 to 0.552 mm/min after 60 min of fire exposure and further reduced from 0.503 to 0.351 mm/min after 120 min fire exposure for double modified laminas. Compared to the control, glulam columns containing a single modified lamina showcased a 31 % increase in residual bearing capacity at 60 min fire exposure duration and a 62.1 % increase at 120 min with double modified laminas. ABAQUS simulation results corroborated experimental findings, highlighting substantial enhancement in fire resistance achieved due to the modified laminas in the fire-side zone.
Wood-polymer hybrid material was prepared using an easily scalable supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP) concept with low ppm catalyst ...concentration. Polymers with hydrophobic characteristics – poly (n-butyl acrylate) (PnBA), poly (tert-butyl acrylate) (PtBA) and poly (methyl methacrylate) (PMMA) were grafted from the fir wood surface in a controlled manner, proved by linear first-order kinetics of polymerization in solution and low dispersity (Mw/Mn = 1.12) of the polymers formed in the reaction mixture. Moreover, the thickness of the polymer brushes grafted from the wood surface was estimated based on the measurements performed for brush decorated silicon wafers that were placed in the reaction mixture. Scanning electron microscopy (SEM) proved successful coverage of the wood by a covalently attached polymer layer, going from sharp-edged untreated wood surface with clearly visible wood cell wall structural elements, to full coverage rough texture with no visible structural components. Water contact angle (Θ) measurements indicated excellent hydrophobic properties of the prepared biohybrid material (Θ ~138°) without notable changes after 120 s of water droplet exposure. Water and acid solution uptake tests confirmed a significant improvement in resistance for absorption of wood samples after modification with polymers.
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•SARA ATRP as an economic and industrial relevant approach for wood modification.•SEM visualization of (meth)acrylates decorated fir wood specimens proved coverage by a polymer layer.•Significant improvement of fir wood hydrophobicity by a covalently attached polymer layer.
Wood-based multifunctional materials with excellent mechanical performance are increasingly considered for sustainable advanced applications due to their unique hierarchical structure and inherent ...reinforcing cellulose phase orientation. Nonetheless, a wider multipurpose utilization of wood materials is so far hampered because of constraints arising from scalable functionalization, efficient processing, facile shaping as well asnatural heterogeneity and durability. This study introduces a multifunctional all-wood material fabrication method relying on delignification, ionic liquid (IL) treatment, and pressure-assisted consolidation of wood. Structure-retaining controlled delignification of wood was performed to enable direct access to the hierarchical cellulose assembly, while preserving the highly aligned and thus beneficial wood structural directionality. As a following step, the obtained biobased scaffold with an increased porosity was infiltrated with an IL and heat-activated to partially dissolve and soften the cellulose fiber surface. Samples washed with water to remove IL exhibited pronounced isotropic flexibility, which upon combined compression and lateral shear allowed the fabrication of various 3D shapes with adjustable fiber architecture. The obtained very compact and totally additive-free all-wood materials were extensively characterized, revealing superior mechanical performance, and gained multifunctionality compared to native wood.
SUMMARY
Wood and wood‐based products are widely used for structural building elements, but due to their composition, they are susceptible of combusting if exposed to fire. Fire safety is an important ...issue of building safety, especially when the building's fire load contents enhance the risks of fire spread. Therefore, the involved materials are very important to address the fire safety requirements. When existing timber structures are involved, the most usual way to improve its reaction to fire is to treat wood with fire retardant materials.
The idea of this paper is to give an overall overview, on the existing fire‐retardant and intumescent coating materials, modification, and treatments that can be applied to wood and wood‐based products in order to improve their reaction to fire.
Wood is undeniably the most useful and readily available natural raw material. However, the susceptibility of wood products to fire is one of the crucial challenges faced in the wood industry. The ...fire behaviour of wood is a very complex phenomenon due to the different constituents and their independent reactions to fire. This article presents a thorough overview of the flammability stages of wood. It covers pyrolysis, thermal oxidative decomposition, ignition, combustion and heat release as well as flame extinction mechanisms. In the area of flame retardancy, conventional wood fire retardants, nanocomposites fire retardants and wood modification processes are investigated. Factors such as wood species, moisture content, density, experimental conditions such as external heat flux, heat exposure time, wood permeability and porosity are some of the deterministic parameters characterising the fire behaviour. This paper is a one-stop-shop for researchers analysing wood flammability due to the inclusion of all aspects pertaining to the burning of wood.
Mass timber (MT), a group of large engineered structural wooden panels such as cross-laminated timber (CLT), glue-laminated timber (Glulam), laminated veneer lumber (LVL), etc., is becoming ...increasingly popular due to sustainable construction. Despite the numerous benefits of MT-based buildings, such as low-carbon emission, short construction time, and cost-effectiveness, the concerns regarding the durability of MT may limit their market acceptance. In this review, we discuss the advantages and opportunities of applying MT in tall buildings, as well as the durability issues associated with MT application. We examine the traditional wood protection techniques including, preservative treatment, thermal and chemical modification, and discuss the potential of applying these techniques for MT protection. We survey the recent studies on MT durability evaluation, as well as the recent progress in MT structure protection through a moisture control strategy. Finally, we highlight the MT protection strategies through the preservative, thermal, and chemical treatment approaches, review the effects of these treatment methods on the properties of MT such as wettability, glue penetration, bonding strength, etc., and discuss the future of the field.
•Numerous opportunities that exist for mass timber in construction were given.•The implementation of current wood protection protocols to mass timber was explored.•The pros and cons of mass timber protection were discussed.•Further recommendations on evaluating the durability of mass timber were given.•The impacts of treatment on the properties of MT were discussed.
Wood modification can be broadly categorized into chemical and physical processes, with acetylation and heat treatment being two of the most common methods in each category, respectively. This study, ...for the first time, combines these two modification methods and investigates the effects of high-temperature vapour-phase acetylation (HTVPA) on the physicomechanical properties of Japanese cedar (Cryptomeria japonica) wood in the temperature range of 145 to 220 °C for 2 to 16 h. Additionally, the acetylation variations within the wood were evaluated. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and near infrared spectroscopy (NIR) spectral analysis showed that the hydroxyl group of Japanese cedar wood reacted with acetic anhydride to form an acetyl group by HTVPA process. When the HTVPA temperature was 220 °C, dehydration and deacetylation of wood occurred. Furthermore, based on the weight percent gain (WPG) and physicomechanical properties of the treated wood, the 200 °C/8h was considered the optimal HTVPA treatment condition. The profiling analysis results showed that the acetylation depth in the longitudinal direction was 40 mm, while the depth in the tangential and radial directions was 3–4 mm. However, the theoretical WPG of the surface of HTVPA treated Japanese cedar wood was 30.0–31.6 %.
Wood modification using polyesterification of sorbitol and citric acid is a novel environmentally friendly strategy for wood protection improving its dimensional stability and acts against fungal ...deterioration. Inelastic Raman scattering is sensitive to the molecules of high polarizability and both lignocellulose and aliphatic esters formed during the treatment are polar. Therefore, in the present study, the quality control of the treatment using a handheld Raman spectrometer equipped with 830 nm laser is suggested as a rapid and reliable approach. Raman spectra from six wood modification levels (resulting in different weight percent gain, WPG) of three different wood species (Silver birch, Scots pine and Norway spruce) as well as three sample preparation strategies (intact, sanded and milled wood samples) were collected, and further analyzed using a chemometric method. Best performing models based on Powered Partial Least Squares Regression predicted the WPG level at R2 = 0.85, 0.95 and 0.98 for birch, pine and spruce, respectively. In addition, a clear separation between hard and soft wood species was also captured. Especially for softwood species, the sample preparation method affected the model accuracy, revealing the best performance in milled material. It is concluded that by using handheld Raman spectrometer it is possible to perform accurate quality control of wood modified by polyesterification of citric acid and sorbitol.
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•A quick and accurate quality control is required for broad application of wood protection using sorbitol and citric acid.•Handheld Raman spectrometer is a promising tool for quality control of wood treated with citric acid and sorbitol.•Chemometric modeling allows to predict the weight percent gain (WPG) level with high accuracy for birch, pine, and spruce.•The sample preparation method affected the model accuracy, with milled material performing the best for softwood species.
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