European Journal of Wood and Wood Products最新文献

Understanding the effects of intact anatomical structures on bamboo shrinkage is crucial for mitigating shrinkage-induced defects in bamboo-based products. However, the effects of bamboo boundary layers (epidermis and pith ring) and their interactive mechanism with vascular bundles (VBs) remain unexplored. This study aims to quantify the effects of these boundaries on shrinkage and clarify how VB content modulates shrinkage under their joint constraints. The results show that the epidermis and the pith ring significantly inhibit radial and tangential shrinkage, while promoting longitudinal shrinkage. This inhibitory effect is further clarified by real-time monitoring, which reveals that the maximum tangential shrinkage (12%) occurred in the mid-VB content areas (37 VB% to 42 VB%). This phenomenon arises because boundary constraints restrict shrinkage in both VB-highest and VB-lowest areas, demonstrating that boundary effects override the influence of VB content gradients. Therefore, the epidermis and pith ring redistributed the shrinkage strain by restricting adjacent zones, thereby localizing maximum strain and crack formation in the mid-VB content areas. This study provides insights into the synergistic effects of anatomical boundaries and VB gradients on bamboo shrinkage, offering a theoretical basis to design low-shrinkage bamboo-based materials.

This research presented a comprehensive investigation of the influence of microwave (MW) treatment on the technological properties of maritime pine (Pinus pinaster) heartwood, including physical, microscopic, chemical, biological, and mechanical performance. Two MW configurations were applied: 400 W and 25 min (MW_400) and 700 W and 5 min (MW_700W). MW_400 treatment significantly improved wood impregnability, enabling 70% higher preservative uptake while maintaining low leaching (4%). The results indicated that MW_400 samples were more stable dimensionally than MW_700, which may be related to the reduction in hemicellulose (12%) and rise in lignin content (22%) of MW_400 samples. The synergistic effect of MW_400 combined with preservative treatment resulted in the highest biological resistance, with reductions in fungal mass loss of up to 54.4%, thereby classifying the wood as resistant. A reduced impact in bending strength (-1% for MW_400 and − 8% for MW_700), modulus of elasticity (-1% for MW_400 and − 4% for MW_700), and compressive strength (-12% for MW_400 and MW_700). MW treatment did not increase the wood’s brittleness. Overall, the MW_400 treatment demonstrated superior performance compared to MW_700, particularly when combined with preservative impregnation, resulting in improvements in dimensional stability and durability while preserving mechanical integrity. Hence, MW-treated wood samples present promising possibilities as construction materials, and MW technology can be a useful, sustainable, and modern methodology for wood treatment.

Understanding the effects of intact anatomical structures on bamboo shrinkage is crucial for mitigating shrinkage-induced defects in bamboo-based products. However, the effects of bamboo boundary layers (epidermis and pith ring) and their interactive mechanism with vascular bundles (VBs) remain unexplored. This study aims to quantify the effects of these boundaries on shrinkage and clarify how VB content modulates shrinkage under their joint constraints. The results show that the epidermis and the pith ring significantly inhibit radial and tangential shrinkage, while promoting longitudinal shrinkage. This inhibitory effect is further clarified by real-time monitoring, which reveals that the maximum tangential shrinkage (12%) occurred in the mid-VB content areas (37 VB% to 42 VB%). This phenomenon arises because boundary constraints restrict shrinkage in both VB-highest and VB-lowest areas, demonstrating that boundary effects override the influence of VB content gradients. Therefore, the epidermis and pith ring redistributed the shrinkage strain by restricting adjacent zones, thereby localizing maximum strain and crack formation in the mid-VB content areas. This study provides insights into the synergistic effects of anatomical boundaries and VB gradients on bamboo shrinkage, offering a theoretical basis to design low-shrinkage bamboo-based materials.

Wood dust generated by CNC machines during milling is hazardous to human health. This study aims to determine the wood dust emissions (PM2.5, PM10) according to the wood species, spindle speed (12000 rpm, 15000 rpm, and 18000 rpm), feed rate (3 m/min, 6 m/min, and 9 m/min), and cutting direction (contours, linear and spiral), and to predict them with machine learning algorithms. Oriental spruce (Picea orientalis L.) and Scots pine (Pinus sylvestris L.), known for their low and high dust emission values, respectively, were used as wood species. A blade with a diameter of 3 mm was preferred as a cutter for milling both wood species. The results of the analyses show that spindle speed, feed rate, and cutting direction parameters have a significant effect on PM. According to the PM2.5 and PM10 values, the highest wood dust emissions were measured at 121.42 µg/m³ and 173.02 µg/m³, respectively, in Scots pine wood material, with a spindle speed of 18,000 rpm, a feed rate of 3 m/min, and cutting direction being linear. The lowest wood dust emission was measured as 4.20 µg/m³ and 7.40 µg/m³ for PM2.5 and PM10 values, respectively, at a feed rate of 6 and 9 m/min, 15,000 rpm in Oriental spruce wood material under the conditions of cutting direction. However, the Cubist model performed best among the machine learning algorithms for predicting PM2.5 and PM10 levels. This study aims to provide data on wood dust emissions during CNC milling to inform the development of CNC parameter adjustments that minimize dust generation.

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.