European Journal of Wood and Wood Products最新文献

Glued laminated bamboo (GLB), recognized as a sustainable and eco-friendly construction material, is increasingly being utilized in the construction industry. This study presents an investigation into the compressive performance of GLB parallel to the grain across a temperature range from 20 °C to 250 °C. The research analyzed the failure modes, stress-strain curves, compressive strength, and elastic modulus of GLB. The findings of the research indicate that as the temperature increases, the failure mode shifts progressively from fiber buckling to delamination of the glued layers. Both the compressive strength and the elastic modulus show a gradual decline, with reductions of 89% and 87%, respectively, at 250 °C. A damage constitutive model, which incorporates thermal and mechanical damage variables based on the three-parameter Weibull distribution, is proposed. The validity of the proposed model is confirmed through comparative analysis with experimental data. The study concludes with a discussion on the damage evolution of GLB under elevated temperatures and compressive loads, offering valuable insights for the structural application of GLB material at elevated temperatures.

Wooden construction material is a sustainable contribution to carbon sequestration and long-term storage. Despite its strength, sustainability and versatility, the vulnerability to biodeterioration is an issue. Therefore, this study aimed to identify the differences in mould growth features and surface extractive composition of the Scots pine (Pinus sylvestris L.) sapwood sideboards between air- and kiln-drying methods using multivariate data analysis. Air and kiln-dried sideboards were used to extract different low molecular compounds from the surface layer, assess the moisture content, and conduct a mould test. Principal component analysis revealed the grouping of the drying types. This was confirmed by partial least-squares discriminant analysis, which allowed the sideboard characteristics of the two wood drying types to be described. An outlier was detected among the air-dried observations. The collected data show more intensive mould growth on kiln-dried Scots pine sideboards than on air-dried ones. Higher amounts of total lipophilic compounds, phenols and inorganic components were found on the kiln-dried sideboard surface. Also, surface extractives from kiln-dried sideboards contained higher amount of almost all analysed fatty and resin acids, except for the oleic acid, which was more prevalent on the air-dried sideboard surface. Low-molecular-weight sugars, namely glucose, saccharose and fructose, were present in significant amounts on the surface of the kiln-dried sideboards. This has presumably contributed to the rapid spread of mould. In general, multivariate modelling allowed to establish that the method of wood drying significantly influenced the redistribution of extractive components on the surface and the subsequent mould growth.

To tackle formaldehyde emissions from building materials and increasing electromagnetic radiation pollution, the development of lightweight, efficient, and eco-friendly electromagnetic interference (EMI) shielding materials has gained growing momentum. Herein, high-consistency mechano-enzymatic (HCME) pretreatment followed by hot pressing was employed to transform bamboo processing residues into bamboo self-bonding composites (BSBC). The effects of enzyme dosages and pretreatment durations on the microstructure and materials properties of BSBC were systematically investigated. The results revealed that higher enzyme dosage, longer pretreatment duration, or a combination thereof were favorable for the formation of abundant sub-fibrous branches and a more compact physical entanglement, thereby leading to strengthened BSBC. With an enzyme dosage of 0.035 g/g biomass and a 4-hour HCME duration, the BSBC achieved excellent flexural strength (37.1 MPa) and internal bonding strength (2.42 MPa), increasing by 61.1% and 66.9%, respectively, compared to those without HCME pretreatment. Additionally, the BSBC exhibited a low thickness swelling rate (5.6%) and low porosity (3.08%), meeting the standard requirements for general-purpose high-density fiberboards. The incorporation of graphene further endowed the BSBC with effective EMI shielding performance, achieving an EMI shielding efficiency of 31.94 dB. The adhesive-free, environmentally friendly, and green manufacturing features, along with the superior EMI shielding performance and mechanical performance, make it a promising sustainable EMI shielding material to be potentially used in secure conference rooms and data centers.

Monotonic axial compression tests were conducted on seawater sea-sand concrete columns confined with bamboo sheets (SSCCCBS) in this study. The effects of the number of bamboo sheet layers (NBSLs) (i.e., 1, 2, 3, 4, and 5 layers) and the angle of bamboo sheet reinforcement (ABSR) (i.e., 0° and 45°) on the mechanical properties of SSCCCBS were examined. Experimental results indicated that the failure mode of SSCCCBS specimens exhibited serrated cracks in the middle that extended longitudinally toward the ends. As NBSLs increased, the strength and ductility of SSCCCBS specimens showed significant improvement. The ultimate stress, ultimate stress increase ratio (({f}_{cu}/{f}_{co})), ultimate strain increase ratio (({varepsilon }_{cu}/{varepsilon }_{co})), and energy absorption rate of SSCCCBS specimens demonstrated an upward trend, with more pronounced increases in specimens with 0–3 layers of bamboo sheets and less pronounced increases in those with 3–5 layers. The current model was employed to predict the experimental outcomes and the results were compared with the test data. Based on the current model, improved models for ultimate stress, ultimate strain, and axial-lateral strain applicable to SSCCCBS were proposed, and the predicted results exhibited alignment with the experimental values.

In this study, the effect of natural weathering on the physical and mechanical properties of two types of bamboo, Dendrocalamus asper, and Phyllostachys edulis was investigated. Twelve bamboo culms of each species were prepared, with six from each group treated with an 8% w/v disodium octaborate tetrahydrate (DOT) solution. The culms were half-buried in the soil for 33 months. After this period, the samples were removed, and the appearance condition of the exposed and buried parts was investigated regarding cracks and degradation. For microstructure characterization, the images were analyzed by SEM (scanning electron microscopy) to assess the changes in untreated and treated samples after natural aging. Physical and mechanical tests were carried out on all the samples, pre- and post-weathering. The results indicated no significant difference in the flexural strength of exposed parts between treated and untreated samples. For the buried section of both bamboo species, all untreated samples had rotten. Although the treated culms exhibited less degradation than the untreated ones, their use is not recommended, as the buried portions of the treated bamboo demonstrated more fragile behavior than the exposed parts. Despite the maintenance of mechanical properties in the exposed sections after ageing, the appearance of cracks caused by humidity variation and UV exposure could lead to weak points on the structure.

Developing eco-friendly, high-performance fibers requires a deep understanding of the interplay between chemical and physical properties and processing conditions. Peracetic acid (PAA) pulping offers a sustainable alternative to conventional methods, decomposing into water and acetic acid, while providing higher selectivity for lignin removal and lower energy demand. This study aims to optimize PAA pulping conditions to maximize lignin removal while retaining hemicellulose and cellulose, thereby improving fiber quality for applications in biocomposites and paper products. PAA pulping was conducted under systematically varied conditions, with temperatures ranging from 70 to 90 °C and reaction times from 60 to 180 min at a 3 wt% solid load. The conditions were selected based on the reaction spectrum of PAA, which becomes feasible for pulping above 70 °C. To operate at atmospheric pressure and avoid excessive degradation, temperature was limited to 90 °C. The study (1) investigates the effect of these parameters on pulping efficiency, (2) evaluates chemical composition and structural changes through lignin content analysis, carbohydrate profiling, and fiber morphology characterization, and (3) determines mechanical performance through tensile testing of paper sheets before and after hot pressing. Optimal results at 80 °C for 120 min led to increased inter-fiber bonding (106.13 Nm/g), significant hemicellulose retention, and substantial lignin reduction. These findings underscore the potential of PAA pulping as an energy-efficient, sustainable method for producing tailored holocellulose fibers with applications in biocomposites and other renewable materials, highlighting a promising strategy for valorizing wood byproducts and reducing carbon emissions.

Natural weathering gradually turns wood light grey over years, driven by exposure to sunlight, precipitation, and biological agents. Nontoxic chemicals have been used to accelerate artificial weathering-induced colour changes in wood. This study aimed to evaluate the effectiveness and underlying mechanisms of various surface treatment chemicals and a commercial silicon-based product in accelerating UV-induced colour changes in birch and aspen under artificial weathering conditions. Weathering was conducted by using an artificial weathering testing instrument with or without spraying the samples with water. Colour changes were measured with a portable spectrophotometer. Hyperspectral imaging data were included to visualise spatial variations of colour in wood samples. The use of water was a significant factor in determining the colour change in wood. Mostly photodegraded lignin constituents leached out of the wood with water spraying but remained if it was not used. The treatment chemicals caused distinct colour changes: Iron (II) sulphate caused dark grey staining, citric acid a unique red colour, sodium hydroxide darkening and brown hue, and hydrogen peroxide the most uniform colour. Commercial silicon-based product caused either little or no noticeable colour change over control samples. The greatest potential for colour change occurred during the first hours of artificial weathering. Spatial data of hyperspectral images allowed for more accurate estimation of variability over spectrophotometer data, and use of hyperspectral imaging in further research is therefore suggested.

The aim of the present work was to decrease formaldehyde emission and improve the dimensional stability of the wood-based panels bonded with urea-formaldehyde resin modified by deep eutectic solvent (DES) nanolignin. For this reason a deep eutectic solvent composed of Choline Chloride–ZnCl2 (ChCl-ZnCl2) was employed to pretreat nanolignin. The DES- modified and unmodified nanolignin were used to replace a part of urea (10%, 20%, and 30%) to prepare the lignin-urea- formaldehyde (LUF) wood adhesive. The changes in curing temperature and chemical structure of the LUF resin were determined by Differential Scanning Calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), respectively. The physico-chemical analysis showed that the UF resin with DES-modified nanolignin had higher solid content, viscosity and faster gel time than those using unmodified nanolignin. FTIR analysis indicated that the methoxy groups decreased and the phenolic hydroxyl groups increased by DES nanolignin modification. The DES-treated nanolignin LUF resin showed a lower peak temperature than those prepared using unmodified nanolignin. Moreover, the panels made from modified nanolignin presented a better mechanical strength (internal bond (IB) strength, flexural strength and flexural modulus) and dimensional stability as well as lower formaldehyde emission than those with unmodified nanolignin. The control UF resin presented a faster gelation time and higher viscosity than both unmodified and modified LUF resins. The mechanical strength of the particleboard bonded with the control UF resin was also better than the panels bonded with both modified and unmodified LUF resins. It should nonetheless be noted that the IB and flexural strengths of the panel bonded with a UF resin with 10 wt% DES-modified nanolignin were comparable to those bonded with the control UF resin. Based on these results, increasing the substitution degree of urea with DES-modified nanolignin significantly improved the dimensional stability and the formaldehyde emission of the particleboards bonded with a UF resin.

To obtain more information on possible reasons for the increased durability of surface charred wood, the chemical changes of surface contact-charred Norway spruce (Picea abies L.) were investigated by ATR-FTIR spectroscopy and pH value measurements. Temperatures of 300 °C, 350 °C and 400 °C were used to carbonize the surfaces of specimens for a duration of ≈ 3 min per surface. Measurements were conducted not only on the surface of the specimens but also on areas underneath the surface by removing material in steps. By that a “depth profile” of chemical changes could be created. Overall, the results of the applied methods seem to confirm the literature regarding the occurrence of different temperature zones in areas below the surface where different chemical changes occur. Concerning possible reasons for the increase in durability of charred wood, the formation of phenolic compounds during pyrolysis could be determined.

This study investigates the mechanical properties and the deformation pattern of silver birch (Betula pendula) and black locust (Robinia pseudoacacia) wood species under impact loading conditions. A drop-release impact testing machine tested the specimens in 3-point bending while a high-speed camera recorded the impact events. Subsequently, the recorded images were processed using the digital image correlation method to analyze deformation and strain behaviour. Basic physical properties of the specimens were determined, alongside test results such as maximum dynamic applied force, maximum deflection, and maximum normal tensile strain up to breakage. Also, the impact bending strength of the specimens was assessed. The maximum deflection and normal tensional strain of them were comparable. Both species had a similar impact bending strength value. Additionally, both species’ normal and shear strain distributions were determined for three levels of deflection in bending. This research contributes to a deeper understanding of these two wood species’ response to dynamic loadings, facilitating the development of more accurate predictive models and engineering designs.