Properties of Thermally Modified Woods by a Brazilian Process Eraldo Antonio Bonfatti Júnior; Elaine Cristina Lengowski; Silvana Nisgoski ...
Environmental Sciences Proceedings,
10/2022, Letnik:
22, Številka:
1
Conference Proceeding, Journal Article
Recenzirano
Odprti dostop
Thermal modification processes are strategies used to improve the properties of wood with an environmental liability when no chemicals are used. The Vap HolzSysteme®, developed in Brazil, promotes a ...thermal modification in wood when using an atmosphere saturated with water vapor thus ensuring a low oxygen content in the pressure system. To evaluate this process, samples of Pinus taeda and Eucalyptus grandis woods were treated in an industrial autoclave at a final cycle temperature of 160 °C. Consequently, the anatomical characteristics were maintained; however, equilibrium moisture, basic density, chemical composition, and mechanical properties were modified. Some modifications were different considering the wood species, mainly in their mechanical properties.
The wood preservation industry has taken large leaps to develop and produce chemicals that protect wood from microorganisms and weathering degradation with no or low environmental impact. These ...improvements occurred after concerns of federal and public agencies about the release of toxic components into atmosphere, soil, and water. These days, reduction in use of non-renewable resources is a crucial concern. Wood and wood-based products are generally low in CO
2
emissions and can be gained from sustainable forest resources. Therefore, they can play a significant role as renewable resources. In comparison to other building materials, wood has numerous advantages, such as suitable thermal insulation, high strength to weight ratio, easy machinability, and attractive esthetics. Wood as a valuable building and industrial material requires to be protected due to its biodegradable properties especially when it is submitted to harsh conditions. Wood durability can be improved through wood protection which include wood preservatives and modification systems. Wood protection should be safe to use, efficient, cost-effective, permanent, and should not corrode metal or degrade wood components. Numerous reviews of wood protection can be found in the scientific literatures, but until now a review of a combination of wood preservation and wood modification has not been studied. It should be considered that the latest research projects in wood protection in academia not always reflect the most current developments in the industry due to exclusive rights. The findings reported in academia contribute to the safe use of preservatives, advancement of wood modification techniques, as well as recycle and disposal of treated material. Therefore, in this study, the most current research and advancements promoted in the wood protection in academia are discussed which including an overall summary of the recent developments on wood preservatives, different types of preservatives, natural preservative compounds, and modification technologies in academia.
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•The recycling of PLA, after one-process, had substantial effect on the overall crystallinity.•The addition of wood, even in small inclusions (2.5 wt%), had substantially improved the ...PLA crystallinity.•Modification of wood fiber with DDSA had pronounced effects on the WPC’s water absorption properties.•Substitution of pristine wood to DDSA-modified wood has no effect on mechanical properties.•Synergistic effects of maleated-PLA and DDSA-modified wood further enhanced WPCs water-resistant properties.
This study investigated the effects of simulated recycling of PLA and Maleated PLA using thermo-mechanical processes on its structure and physico-chemical properties and combined with pristine and modified wood flour (WF) for biocomposites. The WF modification entails a base catalyzed reaction of dodecenylsuccinic anhydride to effectively reduce its polarity and enhance the system’s compatibility. Recycling of PLA had a profound effect on PLA’s crystallinity and modulus. The addition of WF had significantly affected PLA’s crystallinity and moduli of the fabricated biocomposites. The modifiedsamples had superior water repellent and dimensional stability capabilities of the wood-plastic composites.
•Effects of oil heat treatment on wood are reviewed.•Advantages and disadvantages of using vegetables are discussed.•Different types of treatment procedures are compared.•Factors governing the ...treatment effectiveness are listed.•Potential applications of oil heat treated wood are discussed.
Wood is an ideal building material as it is renewable and green. However, low dimensional stability and durability might restrict its usage in structural application. Therefore, modification is needed to improve the aforementioned issues. As an environmentally friendly wood modification method, heat treatment of wood using oil as a heating medium has brought to researcher’s attention to the fact that it might serve as an excellent treatment procedure in treating wood. This paper presents a review about the effects of oil heat treatment on the properties of wood such as colour stability, dimensional stability, mechanical strength and durability against termites and fungi as well as its potential to be used as construction and building materials. The pros and cons of using oil as a heating medium in wood treatment are discussed. This review shows discrepancies between the treatment methods or procedures and its resultant findings. Moreover, the effectiveness of the treatment is governed by several factors such as the type of oils used and wood species. The objective of the present paper is to conduct a review of the published literatures regarding the properties of wood modified by oil heat treatment and the results obtained were compared systematically.
Improving the environmental performance of resins in wood treatment by using renewable chemicals has been a topic of interest for a long time. At the same time, lignin, the second most abundant ...biomass on earth, is produced in large scale as a side product and mainly used energetically. The use of lignin in wood adhesives or for wood modification has received a lot of scientific attention. Despite this, there are only few lignin-derived wood products commercially available. This review provides a summary of the research on lignin application in wood adhesives, as well as for wood modification. The research on the use of uncleaved lignin and of cleavage products of lignin is reviewed. Finally, the current state of the art of commercialization of lignin-derived wood products is presented.
This article aimed at thermally treating and charactering the Eucalyptus grandis wood under three different temperatures.
For this, pristine eucalypt samples were treated by heating in a laboratory ...oven at 160 °C, 200 °C and 240 °C, always for 2 h. Treatment parameters (based on weight percentage loss and specific gravity), as well as mechanical (by hardness tests), chemical (by infrared spectroscopy), thermal (by thermogravimetry), and colorimetric (by CIELab method) features were evaluated. Compared to the pristine ones, the treated woods have there was a drop in apparent density at 12 % and consecutively greater thermal stability which is probably related to a previous partial degradation of some major amorphous components (namely cellulose, hemicellulose and lignin), as suggested by the treatment parameters and infrared spectra. Besides of that, the higher the temperature treatment, the higher the loss in surface hardness and the higher the colour darkening. KCI Citation Count: 4
Chemical modifications are widely used to enhance the properties of wood composites and create a strong bonding mechanism for enhancing the dimensional stability, water resistance as well as ...decreasing carcinogenic formaldehyde emission. Esterification is the most-known modification way to enhance the durability of wood composites, but it does not improve mechanical performance. In this work, we demonstrated a two-step, easy and quick wood surface modification strategy based on microwave heating and UV crosslinking. Firstly, the fiber surface was reacted with methacrylic anhydride, then using methacrylated groups on wood, the fibers are covalently linked. As a proof-of-concept the fibers cross-linked within five minutes under UV radiation using benzophenone solution. Then, the effect of crosslinked wood fiber on the properties of mechanical and swelling of fiberboard were studied. Using SEM, FTIR-ATR, and swelling tests, we investigated the wood-based products' reaction mechanism, morphology, and internal bonding strength. The chemical cross-linking gives stronger bonding, compared to hydrogen bonding, between fibers even in wet conditions, resulting in a cross-linked foam-like structure. Also, wood panels were fabricated, compared to unmodified fibers, the internal bond strength and dimensional stability of fiberboards increased slightly. Overall, these results show that chemical cross-linking of wood fibers can be a fast and promising way to produce multi-functional wood composites.
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•Rapid and scalable method for direct crosslinking of wood fibers is proposed.•Wood fibers were efficiently methacrylated using microwave in a few minutes.•Methacrylation closed open pits native to the fibers, improving hydrophobicity.•The modified wood fibers were directly cross-linked via UV irradiation in minutes.•Strength and dimensional stability of modified wood panels was notably improved.
The treatment of wood using in-situ polyesterification with citric acid and D-sorbitol (SCA) is a novel method for enhancing wood properties. This method can effectively improve the dimensional ...stability and biological durability of wood. However, achieving effective fixation of polyester in wood at lower curing temperatures has not been achieved. In this study, phytic acid was used to catalyze in-situ polyesterification of SCA. The autocatalytic reaction pattern of SCA polyesterification was elucidated through an investigation of the kinetics of the curing reaction. It was also confirmed that phytic acid reduces the curing temperature and activation energy of SCA. The investigation of polyesters revealed that phytic acid catalysis enhances the esterification degree and thermal stability of the polyester. Wood treated with SCA and 2%wt phytic acid exhibited a 44% reduction in polyester leaching. Moreover, it demonstrated high water resistance and dimensional stability, with water repellency efficiency of up to 33.8% and anti-swelling efficiency of up to 46.2%. Remarkably, it exhibited excellent flame retardancy, with an oxygen index of 33.1% and a 47.5% reduction in total heat release. The outstanding flame retardancy is attributed to the dual action of phytic acid in both the solid phase and gas phase.
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•A whole biobased modification strategy for preparing highly water resistant and flame-retardant wood has been proposed.•Phytic acid catalyzes polyesterification and enhancing wood flame retardancy.•The reaction pattern of citric acid with D-sorbitol catalyzed by phytic acid has been revealed.
Wood has gained popularity as a building and decorative material due to its environmentally friendly and sustainable characteristics. Yet, its long maturation time poses a limitation on meeting the ...growing demand for wood products. This challenge has led to the plantation of fast-growing wood as an alternative solution. Unfortunately, the poor mechanical properties of fast-growing wood hinder its application. In this study, we developed novel densification-modified wood by combining alkali chemical pretreatment, cyclic impregnation, and mechanical hot-pressing techniques. Additionally, the response surface method was employed to rapidly determine the optimal preparation parameters, reducing the cost of preparation under various conditions. The optimized parameters resulted in densification-modified wood with a flexural strength and modulus of elasticity of 337.04 MPa and 27.43 GPa, respectively. Furthermore, the densified wood achieved excellent dimensional stability by reducing the water-absorbing thickness swelling to 1.15 % for 72-h water soaking. The findings indicated that the densification-modified wood possessed high tensile strength and elastic modulus, along with excellent dimensional stability. The proposed densified wood modification technology in this study offers new perspectives and design guidance for the application of outdoor engineering structures, energy-efficient buildings, and decorative materials.
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