European Journal of Wood and Wood Products最新文献

The demand for fire-resistant wood-based materials has grown in response to the increasing urban population density and the widespread construction of high-rise buildings. Inorganic hybridization is a promising strategy to impart hybrid properties to lignocellulosic composites. However, this approach usually leads to a deterioration of the mechanical properties of the resulting composites due to agglomeration of the inorganic particles and insufficient adhesion. In this work, microscopic inorganic particles (ground calcium carbonate, kaolin, fly ash) were pre-mixed with melamine-urea–formaldehyde resin adhesive to solve the agglomeration problem of inorganic particles in organic–inorganic hybrid fiberboards. Additionally, the inclusion of inorganic particles inhibited excessive resin penetration and densified the resulting board, ultimately improving the mechanical properties and flame retardancy of the fiberboards. This work provides a straightforward and scalable approach that enables the well-dispersion of inorganic particles and fosters a strong bonding between wood fibers and inorganic particles to produce high-performance organic–inorganic hybrid fiberboards with higher flame retardancy.

This study investigates the effects of various production parameters on the physical and mechanical properties of one-layer particleboards bonded with canola protein-based adhesives. Two protein-based adhesive formulations, CPI-B-0 with sodium bisulfate and CPI-N-60 with sodium nitrite crosslinkers, were examined under different conditions: binder content, press temperature, and press time factor. Results indicate that the CPI-N-60 outperformed the CPI-B-0 in terms of internal bonding strength (IB), modulus of rupture (MOR), and modulus of elasticity (MOE) due to the stronger covalent bonds formed with primary amines present in the protein adhesive. Increasing binder content led to significant improvements in mechanical properties, with the internal bonding and the MOR increasing by 21% and 9% when using 9% binder content over 7% respectively. The press temperature, as well as the press time were found to yield the highest influence on mechanical properties, with higher values resulting in better performance. Increasing the press temperature from 170 °C to 190 °C led to 33% increment in the internal bonding and 20% in the MOR, while 67% and 28% increment was obtained with 210 °C press temperature, respectively. Increasing the press time also led to an increase in the mechanical properties of the particleboards, by almost the same proportions as the effect of press temperature. The interaction effects between production parameters highlighted the importance of optimized conditions for achieving the desired properties. Indeed, under certain press conditions, the CPI-N-60 outperformed the conventional UF K345, achieving an IB value of 0.8 N/mm² over 0.65 N/mm². Overall, this study contributes to a better understanding of canola protein-based bio adhesive, with implications for the optimization of the production parameters for better boards’ properties.

5-Hydroxymethylfurfural (HMF) and 2,5-dimethylfuran (DMF) were synthesized from Acacia mangium wood sawdust derived glucose through a multistage process. Initially, the Acacia mangium wood sawdust underwent a sulfate cooking process to extract cellulose, which was subsequently subjected to an enzymatic saccharification to produce a glucose solution. The conversion of glucose into 5-HMF was achieved via catalyzed depolymerization utilizing carbonaceous solid acid sulfonated catalysts prepared from various sources including Acacia mangium wood sawdust, coconut shell, sugarcane bagasse, and lignin derived from Acacia mangium wood sawdust. Subsequently, 2,5-DMF was synthesized from the obtained 5-HMF through hydrogenation at 180 °C for 10 h using copper chromite as a catalyst. The conversion of glucose into 5-HMF using the four types of solid acid catalysts was extensively investigated at 120 °C, with the maximum yield of 5-HMF reaching up to 13–28 wt% of glucose after 3–4 h of reaction time. In the case of 2,5-DMF synthesis, the yield was found to be 45–50 wt% of the 5-HMF produced. The integrated scheme for preparing solid acid catalysts and their application in the synthesis of furans from Acacia mangium wood offers an efficient method for converting lignocellulosic biomass into environmentally friendly catalysts and chemicals.

The cork in the Cerrado endemic species Erythrina mulungu and Enterolobium gummiferum was characterized here for the first time in relation to structure and anatomical and chemical features, aiming to reconcile Cerrado native species conservation with income generation for local communities through a sustainable forest management. Both barks showed only one circumferential continuous periderm with a substantial cork layer featuring cork rings and characterized by deep longitudinal fractures originating from stem radial growth. The cellular features of both corks agree with the general characteristics of cork tissues regarding arrangement, topology and dimensions. However, in E. gummiferum the earlycork cells appeared radially stretched and with broken cell walls giving rise to higher tissue heterogeneity. Chemically, the corks of E. mulungu and E. gummiferum are characterized by a very high content in extractives (38.4% and 20.3% respectively), a low suberin content (4.7% and 3.9%, respectively), and high lignin content (36.8% and 38.6%, respectively). The ethanol-water extracts showed a low total phenolics content (27.0 and 32.2 mg GAE/g extract respectively). The cellular features confer to the corks of both species protective insulating properties that are important adaptative characteristics to the Cerrado environment. As regards potential applications, the corks may be used in insulation products with low mechanical resistance requirements, while the high content in polar extractives is indicative of a possible extraction pathway for added value compounds although further compositional and activity studies are needed.

The use of charcoal as a barbecue fuel is a widespread practice around the world. The quality of charcoal is essential to ensure the efficacy and safety of the grilling process. The European standards EN 1860-2:2023 establish the minimum quality requirements for barbecue charcoal for domestic and professional use. Given the significant variability in charcoal production techniques and raw materials, it is crucial to assess whether the commercial products available on the European market comply with standard regulatory requirements. This study evaluated the quality of barbecue charcoal available on the European market over four years: 2020, 2021, 2023, and 2024. A total of 42 charcoal bags were analyzed. Physical and chemical analyses were performed according to the referenced standards. The values obtained were compared with the limits required by the standards. The results revealed a high variability in the qualitative characteristics of charcoal among samples of different brands, both within the same year and in different years. Almost all of the samples analyzed (39) did not meet the standard limits. The most critical factors were low fixed carbon values and granulometry with high percentages of fine and coarse fractions. These findings suggest the need for improved regulations and stricter quality control to mitigate consumer risks.

Forest products measurements based on high-frequency techniques such as microwaves, radio waves or electrical impedance spectroscopy is a growing and maturing field. As high-frequency moisture content meters are being commercialized, the question arises if similar technology can be used to measure additional forest products properties. This review aims to survey literature on high-frequency measurements of properties such as density, spiral grain and heartwood content. Applications to primary forest products such as logs and wood chips are here prioritized over secondary products such as sawn timber and pellets. To promote technical and commercial relevance, the literature search focuses on peer-reviewed and grey literature published within the last twenty years and on commercially available measurement systems. Furthermore, this review focuses on applications under production conditions, taking environmental, logistical, and economic factors into account. High-frequency methods are generally fast, non-destructive, harmless, insensitive to disturbances, and allow for interior inspection and bulk measurement. Disadvantages include high operator skill-level, difficulty in separating frozen and unfrozen material, as well as insufficient studies carried out in a production environment. Moisture content and density measurements are mature applications with high demonstrated accuracy. Spiral grain, knot characterization and bark thickness show potential. The measurement of decay, foreign objects, tree species and chemical analysis of resin or heartwood content need further evaluation, while the measurement of strength properties is unlikely to have sufficient accuracy to compete with other techniques. Promising applications include measurement through large volumes of material, for example in wheel loader buckets or on trucks.

The increasing utilization of polymeric composites stands out as a versatile solution across various engineering fields. To meet the demand for more sustainable and efficient materials, research has been exploring natural and biodegradable sources for the fabrication of these new materials. Among these alternatives, green polyurethane (GPU), derived from castor oil (Ricinus communis), shines due to its sustainability, low toxicity, and abundant availability. However, GPU exhibits limitations in mechanical strength, prompting studies on composites reinforced with synthetic, vegetable fibers, and particles. In this context, cellulose nanocrystals (CNC) emerge as promising due to their rigidity and mechanical strength. However, their industrial production through aqueous dispersion presents challenges in application to polymeric matrices due to resin hydrophobicity. This study proposes a new methodology to extract and incorporate CNC into composites, aiming to characterize the physical, chemical, mechanical, and morphological aspects of a composite material formed by GPU reinforced with different proportions of CNC (0%, 1%, 2%, and 3%). The results demonstrate a significant improvement in mechanical strength, with a 262% increase upon adding 3% CNC reinforcement. In terms of thermal resistance, there was a lower mass loss and alterations in the initial degradation temperature range observed. This study contributes to the understanding of composite properties and their potential in various applications.

The study investigated the production process and properties of a new wood-based material called Bioblocks. This sustainable composite is made from medium-density-fibreboard (MDF) residues, citric acid and either sorbitol or hexanediol. The process involves mixing in-water diluted chemicals with the MDF residues and curing the mixture in a laboratory oven to esterify the sorbitol and wood components with citric acid. A design of experiment was used to determine the influence and optima of the different process factors, and an optimised trial further investigated the material properties. The density distribution, compression strength, and TS after 24 h immersion in water according to EN 317 of the Bioblocks were tested. The first trial showed that mainly the amount of water added impacts the product’s properties. The optimised material achieved a sufficient density distribution with an average density of about 420 kg/m³, a compression strength of up to 3.5 N/mm², and a TS of about 2%. Therefore, Bioblocks are a promising natural material to use waste MDF and substitute fossil, unsustainable materials.

The decay resistance of durable heartwoods is primarily due to heartwood extractives, but some extractives have been found to be degradable by wood decaying fungi. We investigated the degradation of heartwood extractives in Siberian larch by the brown rot fungi Coniophora puteana and Rhodonia placenta and found that neither fungus caused the degradation of flavonoids, the primary organic solvent-soluble extractives in the larch samples. However, both fungi caused the gradual depletion of arabinogalactan, the polysaccharide extractive found in larch heartwood.

Bamboo, which is a crucial industrial material, is characterized by its fast growth, excellent properties, and high transportation efficiency. Bamboo has many advantages as an engineering material; however, many obstacles hinder its practical application. One major obstacle is the lack of understanding regarding its elastic constants, including its elastic modulus, Poisson’s ratio, and shear modulus. Multiple parameters may be required to describe the stress–strain relationship of an anisotropic material. Bamboo is an anisotropic material, and its culm has a hollow structure; therefore, bamboo has many elastic constants that are difficult to measure. Accordingly, this review has three objectives: (1) to examine existing approaches for measuring the elastic constants of bamboo and the difficulties involved in these approaches, (2) to review existing results on the elastic constants of bamboo, and (3) to identify the factors affecting the elastic constants of bamboo. According to this review, several elastic constants of bamboo, especially those in the radial and transverse directions, are currently unknown. However, the vascular bundles in bamboo mostly have a unidirectional arrangement similar to that observed in transverse isotropic materials and consist of high-stiffness vascular bundle sheaths and isotropic ground tissue. Thus, approaches used for measuring the elastic constants of unidirectional fiber-reinforced polymers can be used to measure those of bamboo. This review indicates the direction of research with respect to the elastic constants of bamboo and consolidates existing results on these constants, which can be used as a reference in the industrial application of bamboo.