Search Results (1,477)

This study presents an industrial technology for producing multi-component wood briquettes with controlled raw material dosing, homogenization, and an integrated ATEX-oriented safety architecture. The process enables independent control of three raw material streams—thermally modified wood shavings, untreated dry wood residues, and externally sourced sawdust dried to the required process moisture—allowing controlled formulation of briquette compositions according to raw-material availability. The technology was validated through an industrial-scale trial in a furniture manufacturing plant producing softwood briquettes containing 25–75 wt.% TM pine sawdust. Compared with conventional briquettes, the products exhibited a slightly higher calorific value while maintaining stable mechanical strength. To mitigate the increased ignition and explosion hazards associated with dry, fine TM wood dust, the production system incorporates aspiration and filtration units, explosion vent panels, spark detection and automatic extinguishing systems in pneumatic conveying lines, and spatial separation of drying and briquetting units. Industrial-scale trials confirmed the feasibility of controlled recipe production and product quality. The briquettes achieved a density above 900 kg m⁻³, ash content below 0.3 wt.%, and ash melting temperature above 1100 °C, meeting ISO 17225-3 requirements. The developed technology enables safe, reliable, and flexible briquette production using variable raw material streams. Full article

Considering differences in the penetration and retention of polyethylene glycol with different molecular weights in waterlogged wood structures at different scales, artificially aged waterlogged wood served as the model material. A Box–Behnken response surface design was employed, using low-molecular-weight PEG with molecular weights of 400–800 and solution mass fractions of 29–41 wt.% and high-molecular-weight PEG with molecular weights of 4000–8000 and solution mass fractions of 28–44 wt.% as the independent variables, with volume shrinkage after freeze drying as the response variable for optimization. The quadratic model showed good fit and predictive reliability, with significant interactions between molecular weight and solution mass fraction in both ranges. The optimal two-stage treatment was 35.7 wt.% polyethylene glycol 600 followed by 37.5 wt.% polyethylene glycol 6000, with predicted and experimental volume shrinkage values of 2.34% and 2.43%, respectively. Polyethylene glycol 600 was distributed mainly in the cell wall regions, whereas polyethylene glycol 6000 was distributed in both the cell wall and some cell lumen regions, with relatively pronounced enrichment in some lumina; after two-stage treatment, polyethylene glycol exhibited a more uniform spatial distribution within the wood cellular structure. The optimized treatment achieved an anti-shrink efficiency of 82.91% relative to the water control group, a moisture uptake of 14.3% after 230 h at 85% relative humidity, and a bending strength of 12.97 MPa, 67.79% higher than the water control. Overall, the treatment improved dimensional stability after freeze drying while maintaining favorable moisture stability and relative bending performance. Full article

This study addresses the recycling of construction waste wood and the development of thermal insulation materials by developing a high-belite sulfoaluminate cement-based recycled wood powder thermal insulation mortar (HRTM). High-belite sulfoaluminate cement (HBSC) and building gypsum (GY) were used as hydraulic binders, and recycled wood powder (RWP) was used as a full substitute for natural fine aggregate. The effects of the RWP-to-binder ratio (R/B) and GY replacement ratio on workability, mechanical properties, thermal insulation performance, water resistance, and drying shrinkage behavior were systematically investigated. The hydration products, pore structure, and microstructural evolution were characterized by thermogravimetry-differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, and low-field nuclear magnetic resonance. Increasing R/B reduced dry density and thermal conductivity while improving water retention. The maximum water retention rate was 99.22% at R/B = 1/6 and 15% GY. The mechanical properties and drying shrinkage behaviour varied across the GY series and were influenced by GY replacement, water content, and PCE dosage. At R/B = 1/9 with 10% GY, HRTM exhibited a dry density of 992.19 kg/m³, a thermal conductivity of 0.253 W/(m·K), and a 28 d compressive strength of 23.8 MPa. The microstructural results showed corresponding changes in water-bearing hydration products, matrix continuity, and the RWP–matrix interface. These findings support the use of recycled wood powder in lightweight thermal insulation mortar. Full article

The development of wood-filled thermoset composites for extrusion-based processing requires formulations that combine suitable flow behavior, controlled curing, thermal stability, and adequate mechanical performance. This study examined the augmentation of phenol–resorcinol–formaldehyde (PRF) resin using three modifiers (ball-milled eggshells, gelatinized corn starch and sulfated castor oil) combined with waste wood fibers for extrusion-based manufacturing. Methods: The composite blends prepared by compression molding and extrusion processes were characterized by rheology, thermal analysis and flexural testing. Results: Modified and unmodified wet PRF–wood composite blends exhibited a good frequency-dependent decrease in complex viscosity indicating suitability for extrusion, while temperature-ramp measurements showed an increase in complex viscosity associated with progressive network formation and curing. A thermogravimetric analysis of cured blends showed decreased thermal stability of the modified PRF blends in the presence of wood. The flexural modulus (FM) and strength (FS) of the cured extruded composite blends were higher (FM: 4–6 GPa, FS: 45–68 MPa) than those of compression-molded samples (FM: 3.2–4.3 GPa, FS: 41–58 MPa). Statistically, two-way ANOVA identified significant formulation-dependent effects of modifier type and/or loading on flexural properties within the respective processing groups (compressed or extruded). Overall, the results demonstrate that these modifiers can be used to tailor the rheological, curing, thermal, and mechanical behavior of PRF-based composites while maintaining processability for extrusion. Conclusions: The findings provide a scientific basis for the continued development and optimization of renewable composite feedstocks for extrusion-based manufacturing of wood composite products. Full article

Scots pine (Pinus sylvestris L.) exhibits substantial variation among provenances in growth and wood properties. This study investigated provenance-related variation after nearly six decades of growth under common-garden conditions and examined relationships between tree growth, wood properties and climatic characteristics of provenance origins. The study was conducted in a provenance experiment established in 1966 at the Rogów Forest Experimental Station in central Poland, comprising 16 provenances and five experimental replicates. Tree height, crown length, trunk volume, diameter at breast height (DBH), wood density, dynamic and static modulus of elasticity (MOE_dyn and MOE_st), modulus of rupture (MOR) and compressive strength (CS) were analysed. Provenance significantly affected all traits except MOE_dyn, whereas experimental replicate significantly affected most traits. Correlations calculated across individual trees were generally weak, while provenance-specific relationships varied substantially in strength and direction. At the provenance level, tree height and DBH showed the strongest associations with climatic characteristics of the provenance origins, particularly altitude, mean annual temperature, precipitation, aridity and growing season length. Selected mechanical properties also showed moderate climatic associations. The results demonstrate persistent provenance-related differentiation under common environmental conditions and indicate that growth performance alone cannot reliably predict wood quality. However, the climatic associations should be considered exploratory and do not constitute direct evidence of local adaptation. Full article

Kraft cooking kinetics of poplar wood (Populus deltoides and Populus nigra) were investigated using chips of controlled size, and various enzymatic/mechanical pretreatments of the chips were attempted to observe the effects on pulp quality. Batch kraft cooks of small amounts of untreated wood chips were carried out in mini-autoclaves at a range of 140–165 °C. Delignification rate constants and apparent activation energy during the bulk phase were determined. Various mechanical pretreatments, using a modular screw device (MSD) with or without xylanase impregnation prior to the cooks, were also investigated. Cooks were monitored through pulp yield, kappa number, fiber morphology, viscosity-average degree of polymerization (DPv), and residual effective alkali (REA). The results showed a variable, temperature-dependent activation energy of about 100 kJ/mol for the bulk delignification with a non-linear Arrhenius behavior suggesting a shift from reaction-controlled to diffusion-controlled kinetics as the temperature increased. The effectiveness of xylanase impregnation was limited due to chip thickness that limited enzyme penetration. MSD and MSD-Xylanase pretreatments significantly reduced fiber length (from 871 µm to 845 µm and 784 µm, respectively) and increased fines content (from 20.3% to 26.3% and 29.1%, respectively), indicating degraded fiber quality after the cooks of pretreated chips. Variability in pulp yield and REA was too high to reach statistical significance. Finally, it was shown that neither of these pretreatments could improve pulp quality in terms of fiber morphology and pulp strength properties, but this study opens the way toward the utilization of pretreatments to improve pulp fibrillation for nanocellulose production. Full article

Biochar incorporation in cementitious materials has been widely studied as a cement or binder replacement, but its use specifically as a very-low-dosage fine-aggregate substitute, expressed directly as a fraction of aggregate mass rather than binder mass, remains largely unexplored. This study addresses that gap by systematically comparing three lignocellulosic biochars, corn-stalk (CB), hemp (HB), and beech-wood (BB), incorporated at 0.5% and 1.0% of fine-aggregate mass in a Portland-composite cement mortar (CEM II/B-M (S-L) 42.5R), evaluating fresh-state, hardened-state, transport, and microstructural (SEM–EDS) properties up to 90 days. Results show that even these very low additions produce measurable, feedstock-dependent effects: CB caused the greatest reduction in fresh flow and density, while BB had the smallest effect on workability but produced the largest increase in entrapped air and capillary absorption (+20.5% at 1%, 28 days), along with numerical reductions in compressive (−9.5%), flexural (−12.2%), and splitting tensile strength (−8.2%) at 90 days; of these, only the compressive-strength reduction was confirmed as statistically significant. Feedstock, rather than dosage alone, governed the magnitude of response, and even the most affected mixture retained ~90% of reference compressive strength. SEM–EDS confirmed biochar–matrix integration and linked microstructural heterogeneity to the observed property trends. These findings establish that sub-1% fine-aggregate-level biochar additions are technically viable, with feedstock selection as the critical design variable. Full article

Brewer’s spent grain (BSG) is an abundant agro-industrial by-product with potential for manufacturing sustainable particleboards, although its relatively low cellulose content limits the mechanical performance of the resulting boards. In this study, particleboards were produced from BSG using a soybean protein concentrate (SPC)-based adhesive at three adhesive contents. In addition, rosin surface coating and wood veneer reinforcement were investigated as strategies to improve the performance of the boards. Physical and mechanical properties were evaluated according to American and European standards, while X-ray micro-computed tomography was used to analyze the structure of the panels. Increasing the SPC content significantly improved all mechanical and physical properties. Rosin coating further reduced water absorption and moisture diffusivity while improving the modulus of rupture, modulus of elasticity, and internal bond strength. X-ray micro-CT analysis revealed local density increases associated with rosin penetration into the board structure. The greatest improvement was achieved with wood veneer reinforcement particleboards, satisfying the H1-ANSI A208.1 and P2-EN312 minimum flexural requirements. Moreover, Digital Image Correlation (DIC) revealed that wood veneer reinforcement significantly altered the deformation and failure mechanisms. These results demonstrate that simple surface reinforcement strategies enable the production of bio-based particleboards with significantly improved performance. Full article

Robinia pseudoacacia L. wood is globally recognized for its high density, superior mechanical performance and low dimensional changes. Although widely cultivated across Hungary under diverse environmental conditions, potential regional variations in its wood properties remain insufficiently characterized. This study aimed to investigate the density, linear and volumetric shrinkage and swelling, modulus of rupture (MOR), bending modulus of elasticity (MOE) and compressive strength parallel to the grain (CS) of Hungarian R. pseudoacacia samples across five counties and under three growth conditions. Results indicated significant regional variations (p < 0.05) across some physical and mechanical parameters studied. The mixed stand in poor growth conditions showed significantly higher linear and volumetric shrinkage than pure stands under good and poor growth conditions. Also, the results revealed that samples from Bács-Kiskun county showed the highest density (0.84 g/cm³) and MOE (13.33 GPa). However, samples from poor growth conditions revealed the greatest density (0.81 g/cm³), MOR (131 MPa), and CS (71.90 MPa). These findings suggest that regional site conditions and environmental stressors play a critical role in defining the quality of R. pseudoacacia wood, offering valuable insights for localized forest management and enabling targeted site selection for high-quality timber production. Full article

Static pulling tests are essential for evaluating tree mechanical stability, hence the ability to sustain wind loading. In the tests, the trees are usually pulled in one direction, which can raise concerns about the bias of the estimates due to thigmomorphogenetic adaptations to wind, hence the effect of pulling direction. In this study, the effect of pulling direction on tree mechanical stability estimates (basal bending moment at primary and secondary failures) was assessed based on data collected from trees growing in stands regenerated naturally and by mounding. Scots pine (Pinus sylvestris L.) stands in three sites with slightly differing wind climates in hemiboreal forests in Latvia were studied. Pulling direction (difference between wind and pulling direction) had a significant effect on basal bending moment at fatal failure, indicating pulling direction-related bias that was not affected by stand regeneration. Stand regeneration had a significant effect on susceptibility to primary failure, which is intrinsic permanent wood damage, implying altered strength of storm legacy effects. Primary failure, however, was not affected by pulling direction. Full article

Probabilistic models of glued laminated timber are a required input to structural reliability analysis, and the JCSS Probabilistic Model Code is the reference most analyses adopt without independent verification. This paper reports an experimental programme of 61 small clear-wood specimens of GL24h glulam produced in Croatia, cut from three parent elements from one producer, delivered together as a single lot, covering bending, tension and compression parallel to grain, shear of wood and of the adhesive line, compression perpendicular to grain, and finger joints in tension and bending. All eight strength properties are tested against the reference model with confidence intervals and a family-wise error correction across the eight comparisons. Exactly one deviation survives: the coefficient of variation (COV) of tensile strength parallel to grain is 0.339 against the reference 0.180, with a Holm-adjusted p = 0.0064; no other property is distinguishable from the reference. The measured density COV of 0.026, against a reference value of 0.10, shows directly that the specimens are a cluster sample from three parent elements rather than independent draws from the GL24h population, which makes the elevated tensile scatter the more notable, since clustering suppresses observed variability rather than inflating it. The reliability consequence is then shown to depend on an assumption usually left implicit. Holding the characteristic value at the declared 19.2 MPa, as grading enforces, the reliability index of a tension-critical element falls from 3.30 to 3.09; holding the mean constant, it falls to 2.41. The absolute values depend on the load-duration class assumed for snow, but the contrast between the two treatments does not. Carrying the sampling uncertainty of the COV estimate through the calculation lowers these to predictive values of 2.88 and 1.82. The conclusion is correspondingly narrow: elevated tensile variability matters for the assessment of existing structures, where the mean is measured rather than declared, and for reliability studies that adopt generic parameters and vary only dispersion; it matters little where grading against a fractile is active. Full article

This study explores the development of sustainable composite materials based on phosphogypsum (PG), an abundant industrial by-product, reinforced with olive and eucalyptus wood chips. The objective is to valorize waste streams while enhancing the mechanical, thermal, and acoustic performance of the base material for eco-efficient construction applications. Composites were prepared with fiber contents of 5%, 10%, 15%, and 20% and evaluated through standardized experimental tests. Mechanical behavior was assessed via three-point bending tests, revealing a 26% improvement in flexural strength at 15% eucalyptus content. Water absorption increased with fiber content but remained lower in eucalyptus-reinforced composites due to better fiber–matrix cohesion. Thermal conductivity decreased significantly from 5% to 20% fiber content, reaching 0.60 W/m·K at 20% eucalyptus content, indicating enhanced insulation potential. Acoustic tests, performed using an impedance tube in accordance with ISO 10534-2, showed strong frequency-dependent absorption. The 20% olive composite achieved a peak absorption coefficient of 0.78 and an NRC of 0.68, demonstrating excellent sound-damping characteristics. This work introduces a novel integration of two underutilized Mediterranean biomasses into PG matrices and highlights their multifunctional benefits. The resulting composites offer a low-cost, low-carbon solution for thermally and acoustically optimized building components, advancing circular economy principles in the construction sector. Full article

European beech (Fagus sylvatica L.) was modified by thermal treatment at 180 °C, oligomeric lactic acid (OLA) impregnation followed by catalyst-free polymerization (120 or 160 °C), and their combined application to evaluate changes in mechanical performance and color. The results for untreated beech wood showed low variability; in a four-point bending test, it exhibited an average modulus of rupture of 120.4 MPa and a bending modulus of elasticity of 8.7 GPa. Its compression strength and compression modulus of elasticity were 45.4 MPa and 2.48 GPa, respectively, while the corresponding Brinell–Mörath hardness values were 29.0 MPa on the side and 64.0 MPa on the end grain. Thermal treatment alone maintained bending strength of untreated beech, while highly increasing strength properties. OLA-based treatments generally produced significant reductions in modulus of rupture, bending modulus of elasticity, and deflection at maximum load. OLA-treated specimens exhibited increased brittleness and variability. Color measurements revealed substantial treatment-dependent darkening, with overall color differences ranging from 19.5 to 69.0. The results demonstrate that moderate thermal modification can enhance selected mechanical properties of beech wood, whereas OLA impregnation, especially under severe curing conditions, causes pronounced mechanical deterioration with the curing performed. Full article

Waterborne polyurethane (WPU) has emerged as one of the most promising environmentally friendly coating materials owing to its low volatile organic compound (VOC) emissions, excellent film-forming ability, good adhesion, and versatility in formulation. However, WPU suffers from several intrinsic limitations including inadequate thermal stability, modest mechanical strength, poor flame retardancy, and a lack of inherent antibacterial activity. To address these deficiencies, phosphorylated microfibrillated cellulose (PMFC), prepared from beech wood sawdust via sequential steam explosion, phosphorylation, and superfine grinding, was employed as a substrate for in situ silver nanoparticle (AgNPs) synthesis and subsequent incorporation into WPU via aqueous blending and solvent casting. PMFC functions through a combined mechanism: the hydroxyl and phosphate groups coordinate Ag⁺ ions, providing nucleation sites, while the nanofibrillar network provides steric stabilization against post-synthesis aggregation. The influence of AgNPs loading (1–10 wt% relative to PMFC at a fixed 1 wt% PMFC content) on the morphology, antibacterial activity, silver release behavior, thermal stability, flame retardancy, and mechanical properties of the resulting composite films was comprehensively investigated using free-standing composite films as a model system. At the optimal Ag loading of 5 wt%, the composite exhibited strong antibacterial activity against Escherichia coli with silver release below 1.15 ppb after 96 h, while tensile strength and Young’s modulus increased by 80% and 298%, respectively, relative to neat WPU. At high Ag loadings (70–80 wt%), the composites achieved conductive-level surface resistivity (~3 log Ω) through percolation network formation, demonstrating antistatic functionality. This study provides an effective strategy for fabricating WPU composite films with combined antibacterial, mechanical reinforcement, and antistatic capabilities. Full article

Underwater adhesion is often compromised by interfacial hydration and insufficient bulk properties. Herein, a montmorillonite-reinforced poly (acrylic acid-co-butyl acrylate-co-2-phenoxyethyl acrylate) [P(AA-co-BA-co-PEA)/MMT] liquid adhesive was fabricated by one-pot free-radical polymerization. Solvent exchange and the balanced hydrophilic–hydrophobic composition facilitated hydration-layer displacement and intimate substrate contact, whereas MMT introduced additional physical interactions that restricted chain mobility and reinforced the adhesive bulk. The adhesive achieved underwater lap-shear strengths of 66.01–238.00 kPa on polypropylene, poly (vinyl chloride), polytetrafluoroethylene, wood, 304 stainless steel, and glass, representing improvements of 10.35–157.62% over the MMT-free adhesive. The highest strength, 238.00 ± 5.52 kPa, was obtained on 304 stainless steel. Moreover, the 180° peel strength increased by 23.90% to 107.76 ± 5.12 N m⁻¹, while the swelling ratio decreased by 33.59% to 10.20 ± 1.09%. Rheological and thermal analyses further supported the MMT-induced enhancement of the adhesive bulk. This synergistic regulation of interfacial adhesion and composite reinforcement provides a simple route toward versatile liquid adhesives for robust underwater bonding. Full article