European Journal of Wood and Wood Products最新文献

The introduction of sandwich structures made from materials that are environmentally friendly, light, and strong enough to carry the applied loads is one way of reducing the carbon footprint of the transport industry. This work investigates the impact behaviour of a structure composed of a plywood core and flax/epoxy composite skins, as a proposal for a sandwich structure that takes advantage of the high longitudinal strength of raw timber along the transverse direction across the grain. The variation of peak force, indentation, impact bending stiffness and absorbed energy over a wide range of impact energies is studied, comparing the sandwich structure with the plywood alone. The failure modes (matrix in tension, matrix in compression and delamination) that occur in both the plywood and the sandwich structure have also been studied. The sandwich structure shows superior impact resistance, making it a promising alternative to conventional sandwich structures that is both sustainable and lightweight.

Medium density fibreboard (MDF) is an essential material in global manufacturing, valued for its versatility and cost-effectiveness. Enhancing its water resistance is critical for broadening its applications, especially in humid and outdoor environments. This study investigates the enhancement of MDF water resistance through the chemical modification of the constituent wood fibres (in this case, thermo-mechanical pulp or TMP) through periodate oxidation. The treatment with sodium metaperiodate results in the formation of dialdehyde fibres (DA-TMP) which are then spray-coated with a phenol-formaldehyde resin, following the industrial procedures, and converted into a MDF through proper hot pressing. Comprehensive evaluation of the physical, mechanical, and biological properties is conducted, along with the study of fire behaviour comparing boards made from both oxidized and non-oxidized fibres. The results reveal that periodate oxidation reduces water absorption by 54% and thickness swelling by 56%, indicating significant changes in the fibres’ chemistry and morphology. Despite a slight decrease in mechanical properties, the overall performance of DA-TMP based MDF confirms this as a promising method for achieving superior durability in moisture-prone environments, including outdoor constructions. Importantly, the biological resistance of the material remains unaffected by the oxidation of the fibres, ensuring continued protection against biological attack and long-term durability. Additionally, fire performance tests show that DA-TMP based MDF exhibit reduced peak heat release and smoke production, further enhancing their suitability for fire-sensitive applications. Consequently, this research contributes to expand the use and durability of wood-based materials across various industrial sectors, offering a sustainable and effective alternative to traditional moisture resistance treatments.

Recycling medium-density fibreboard (MDF) enhances material efficiency and contributes to waste management. This study investigates the impact of secondary fibres, generated from recycling of both processing and post-consumer waste, on the properties of new MDF panels. The fibres were recycled using a modified thermo-mechanical pulping (mTMP) and steam treatment (ST) processes. Virgin pine and secondary fibres were studied for their size distributions and morphological features. MDF panels were fabricated by substituting virgin fibres with secondary fibres at 15% and 25% rates, with additional 100% recycled MDF produced using ST-obtained fibres. Secondary fibres from both waste sources were shorter and had more fines than virgin fibres. For recycled MDF incorporating ST fibres, a notable drop in internal bond strength was observed when using fibres from post-consumer fibreboard waste, while modulus of rupture, modulus of elasticity, thickness swelling, and water absorption remained consistent. Increasing substitution rates from 15 to 25% resulted in an insignificant change in the aforementioned physical and mechanical properties. However, MDF produced with 100% recycled fibres exhibited a dramatic decrease in physical and mechanical properties, despite a reduction in formaldehyde content. Compared to MDF with virgin fibres, the internal bond strength of recycled MDF statistically decreased at all substitution ratios. In contrast, other properties were comparable at 15% or 25% rates for fibres produced using the mTMP process. Finally, MDF containing mTMP fibres showed similar density profile values, slightly higher than MDF with ST fibres.

This study examines the potential of using misfit wood—i.e., stem wood that does not meet conventional sawlog standards—in long-lived products in the context of Finland, mainly focusing on the wood construction products industry. The impetus for the use of misfit wood is to improve forest biodiversity and resource-efficiency by repurposing wood material from short-term use to reach its full potential in value creation. However, the use of misfit wood should be done within the scope of sustainable forest management, to ensure that the proposed solution does not contribute to the problem. The research involves reviewing roundwood statistics and conducting interviews with forestry experts, wood products industry professionals, and environmental scientists from Finland. These interviews indicated the presence of some opportunities and challenges associated with repurposing non-standard wooden applications in architecture and construction. While most interviewees were optimistic about innovative uses for misfit wood and highlighted new business opportunities for small entrepreneurs alongside the major material streams within the industry, they also pointed out economic and structural challenges. These include issues related to profitability given the small volumes, obtaining product approvals, and standardizing the materials. The study stresses the importance of ensuring that using misfit wood supports forest biodiversity without depleting resources. It also highlighted a lack of precise information on the specific quantities of wood meeting different characteristic requirements, such as sawlogs, even though data on the annual harvested wood volume and their distribution across various industries is available.

Plywood producers in South Africa historically used P. patula for veneer production. However, in recent years it has become difficult to plant P. patula at lower altitudes due to large scale mortality induced by the fungal pathogen Fusarium circinatum. Subsequently, alternative species, such as P. elliottii and P. taeda were established for veneer production. The wood properties of P. elliottii and P. taeda are inherently different from P. patula and limited knowledge is available on the optimal processing parameters for these species. This study examined how log size (diameter class), storage duration and steaming time impact the veneer quality of P. elliottii and P. taeda. Wet recovery, peeler waste production, dryer throughput and quality recovery were determined and the results show significant differences in wet recovery between the two pine species. This was mostly caused by differences in taper, as P. taeda logs show more taper than P. elliotti. Extended log storage negatively affected wet recovery for both species as fungal induced blue stain was often mistaken for wane, leading to the unnecessary rounding of logs during the rotary peeling process. Logs stored for longer duration resulted in lower veneer grades after drying compared to those processed within four weeks after felling. Log steaming improved peeling performance, enhancing veneer quality without directly affecting wet recovery. Increasing steaming time from 8 to 12 h did not clearly impact wet recovery, but significantly improved veneer quality after drying. Larger logs (mostly from the pruned section of the tree) generally achieved better veneer grades due to fewer knots, while longer-stored logs resulted in more downgrades due to fungal induced blue stain and splitting, likely from moisture loss. P. taeda showed overall better quality recovery than P. elliotti, however, P. elliottii had better volume recovery. Both P. elliotti and P. taeda had about 4% less face veneer recovery compared to P. patula.

In this study, the polystyrene adhesive film was developed using expanded polystyrene (EPS) foam waste dissolved in D-limonene, which is extracted from orange peel. The three-layer plywood was made using polystyrene film as the adhesive between the layers. Styrene maleic anhydride (SMA) as a coupling agent (CA) was used in different percentages and in two different ways to improve the adhesion of wood to the polymer. The best performance was obtained by incorporating SMA compatibilizer into the polystyrene solution to form polystyrene adhesive film. Increasing the amount of compatibilizer up to 10% in the adhesive film structure, resulted in approximately 30% higher shear strength, 34% higher tensile strength, 11.7% higher bending strength and 19.5% modulus of elasticity than in the corresponding samples without compatibilizer. Spraying the compatibilizer onto the surface of the wood veneers did not significantly improve the mechanical properties of the plywood, but it did have a positive effect on reducing the TS after 24 and 168 h of water immersion. The results of the MFI and molecular weight indicators (Mw and Mn) show that the incorporation of SMA into the adhesive film reduces the viscosity of the polystyrene matrix and thus improves the flowability of the polymer. In general, the adhesive films prepared with EPS foam waste dissolved in limonene and 5% SMA as a compatibilizer worked well as an adhesive to produce interior plywood according to the requirements of EN 314-2.

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.