Abstract: The fiberboard industry remains heavily reliant on synthetic, formaldehyde-based adhesives, which, despite their cost-effectiveness and strong bonding performance, present significant environmental and human health concerns due to volatile organic compound (VOC) emissions. In response to growing sustainability imperatives and regulatory pressures, the development of non-toxic, renewable, and high-performance bio-based adhesives has emerged as a critical research frontier. This review, conducted through both narrative and systematic approaches, synthesizes current advances in green adhesive technologies with emphasis on lignin, tannin, starch, protein, and hybrid formulations, alongside innovative synthetic alternatives designed to eliminate formaldehyde. The Evidence for Policy and Practice Information and Coordinating Centre (EPPI) framework was applied to ensure a rigorous, transparent, and reproducible methodology, encompassing the identification of research questions, systematic searching, keywording, mapping, data extraction, and in-depth analysis. Results reveal that while bio-based adhesives are increasingly capable of approaching or matching the mechanical strength and durability of urea-formaldehyde adhesives, challenges persist in terms of water re-sistance, scalability, cost, and process compatibility. Hybrid systems and novel cross-linking strategies demonstrate particular promise in overcoming these limitations, paving the way toward industrial viability. The review also identifies critical research gaps, including the need for standardized testing protocols, techno-economic analysis, and life cycle assessment to ensure the sustainable implementation of these solutions. By integrating environmental, economic, and technological perspectives, this work high-lights the transformative potential of green adhesives in transitioning the fiberboard sector toward a low-toxicity, carbon-conscious future. It provides a roadmap for research, policy, and industrial innovation.

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The objective of this study was to investigate the chlorine-related challenges in Automotive Shredder Residue (ASR) by developing a de-chlorination strategy and formulating Solid Recovered Fuel (SRF) pellets with improved environmental and fuel quality. A ternary blending approach was employed using Fe–Ca-based inorganic dechlorinating agents and thorny bamboo biomass as co-materials with ASR. The de-chlorination efficiency, calorific value, and ash content of the resulting SRF were evaluated. Results indicated that the optimal dechlorinating formulation reduced the chlorine content of PVC from 43.26 wt% to 0.59 wt%, achieving a de-chlorination efficiency of 97.23%. A second-order polynomial regression model（η_DeCl = –1.5277x² + 2.5519x – 0.0225，R² = 0.9347）was developed to predict the de-chlorination performance based on the blending ratio of dechlorinating agent to ASR, demonstrating behavior consistent with first-order reaction kinetics observed in pyrolytic de-chlorination. The final ternary formulation—comprising 55% thorny bamboo, 37.5% ASR, and 7.5% dechlorinating agent—produced SRF pellets with improved overall quality, demonstrating effective chlorine control, reasonable ash content, and enhanced thermal properties suitable for regulatory compliance and practical application. Such findings meet the criteria set by EN ISO 21640:2021 (Class 2), JIS Z7311 (Grade A), and forthcoming Taiwanese SRF regulations. Based on the findings in this work it can be stated that the high de-chlorination potential of Fe–Ca-based additives for chlorine-rich waste and introduces a predictive formulation model that supports both resource circularity and clean fuel production.

Abstract: Phosphorus tailings are solid waste generated from phosphate ore processing, and their prolonged accumulation consumes significant land area and poses a substantial risk to soil and groundwater quality. This study innovatively converts phosphorus tailings into gypsum fiber for papermaking, thereby addressing the issue of excessive accumulation of phosphorus-rich tailings. Experiments were conducted to investigate the effects of slurry concentration, stirring speed, and reaction temperature on the length of gypsum fibers; and the prepared fibers were used as paper fillers for papermaking to investigate the effects of gypsum fiber lengths, mixing ratio, and retention amount on the performance of paper. The findings indicated that at a slurry concentration of 9%, a stirring speed of 50 rpm, and a reaction temperature of 55℃, the resultant gypsum fibers exhibited increased length, elevated aspect ratio. The 100 μm homogeneous gypsum fiber incorporated into paper exhibits superior mechanical strength compared to shorter or irregular gypsum fibers. The research findings present a novel method for the effective and valuable utilization of phosphorus tailings, resulting in solid waste reduction and pollution abatement, while providing a more environmentally friendly source of functional fillers for the paper industry, thereby generating both ecological benefits and potential economic gains.

Abstract: While most efforts are aimed at preventing the surface roughening and colour change of wood due to weathering, some, mainly for decorative reasons, want wooden objects and elements to give the impression that they have been weathered for a long time. In this study, the simulated weathering of numerous softwoods as well as ring-porous and diffuse-porous woods by sandblasting and greying with iron sulphate was investigated. Calculations of the correlations between wood density, orientation, mass loss and thickness reduction by sandblasting, the difference between the hardness of late and early wood and the surface profile parameter Pt showed that the surface profiles correlates strongly with the mass loss, especially in the tangential orientation. Softwoods appeared to be the most promising for simulated profiling, especially spruce and larch with tangential surfaces. Among the ring-porous woods, oak and sweet chestnut also delivered good results.

Abstract: The aim of the study was to develop an optimum method for investigating the change in the content of selected metals in biomass before and after pretreatment by steam explosion. The study included testing the metal content using an X-ray fluorescence spectrometer (XRF) of metals such as chromium, manganese, iron, nickel, copper and zinc. These metals are considered inhibitors of biological processes occurring during biofuel production such as enzymatic hydrolysis, alcoholic fermentation. In this study, a steam explosion process was carried out on poplar wood biomass at selected temperatures in the range 140°C -205°C. The study found the greatest increase in metal content for materials after SE at 175°C. The significant increase in the accuracy of the determination of metals in the material is influenced by the transfer of the raw material to the liquid state.

Abstract: Fast-growing hardwoods like poplar often lack natural durability in outdoor use and require homogeneous impregnation with protective agents, though achieving homogeneity remains a known challenge. Various anatomical structures influence fluid transport in wood. This study compares characteristics of pits in libriform fibres, between ray–vessel interfaces, and between vessel-to-vessel connections in normal wood and tension wood of a hybrid poplar genotype (Populus × canadensis, ‘Gelrica’), including both impregnated (with an aqueos, dye-containing solution) and non-impregnated regions, to identify anatomical barriers to impregnation. Light and scanning electron microscopy revealed significant differences in pit morphology and frequency in libriform fibres between normal wood and tension wood. In non-impregnated regions, pits were often encrusted. Vessel-ray pits did not differ between normal wood and tension wood but showed distinct differences between impregnated and non-impregnated regions: in the latter, pits were occluded by tylose-forming layers. Intervessel pits differed in border and aperture size between earlywood and latewood in both normal wood and tension wood. Hence, fluid transport is strongly impeded by occluded vessel-ray pits and, to a lesser extent, by encrusted fibre pits.

Abstract: A key discovery of this study is the strong correlation (r = 0.96) between excitation and emission maxima across chemically distinct clusteroluminogens. All 157 evaluated peaks fall along a single regression line (Ex = 0.844 Em -12 nm), a pattern that was not valid for conventional fluorophores. This suggests a general principle of clusteroluminescence. We show that in lignocellulosic materials, peak positions reflect chemical interactions: isolated lignin and cellulose showed short excitation and emission wavelengths, while native wood exhibited longer wavelengths. Fungal or photoinduced degradation led to a further red-shift. These effects are attributed to increased molecular heterogeneity, reducing the effective energy gap within the lignocellulosic complex. We conclude that the spectral position reflects the degree of molecular interaction rather than the chemical structure of individual molecules. It may serve as a novel analytical parameter for assessing purity and degradation in a wide range of polymers.

Abstract: Global climate crisis shifts the building industry towards ecological use of materials, often based on renewable sources. Properties of such materials, as well as their behavior in structures, need to be constantly verified both theoretically and experimentally. The article focuses on vapor retarder influence on moisture content of timber log peripheral wall structures with sheep wool insulation. Moisture content was verified experimentally during the period of over 2 years via monitoring sensors and insulation samples weighing. Results show vapor retarder has got a positive and statistically significant impact on moisture content of sheep wool insulation and log structure. This case study can help further the knowledge of log structure design and provide insight into hygrothermal properties of sandwich structures.

Abstract: This study investigates the impact of multilayers and drying strategies on the barrier properties of high-speed starch/bentonite-coated paperboard. The machine speed was 400 m/min. The hypotheses were that thin multilayer coatings reduce oxygen permea-bility more effectively than thick single or double coatings and that gentle infrared (IR) drying is required to engender this effect. The experiments involved coating paperboard up to six times with dry coat weights between 0.5 and 1.5 g/m² in each layer. The IR dryer power ranged from 207 kW to 829 kW, and different IR element positions were tested. The results indicated that thin multilayer coatings resulted in fewer pinholes, lower oxygen transmission rates and improved grease resistance compared with one or two thick layers. However, the effectiveness of the multilayer-coated paperboard was in-fluenced by the employed drying strategy. Specifically, gentle IR drying reduced pin-holes, lowered oxygen transmission rates and enhanced grease resistance.

Abstract: Acid hydrolysis can be more efficient than water hydrolysis, particularly in breaking down cured adhesives found in waste panels within a shorter reaction time that could benefit large-scale industrial processes. This study evaluates the effects of various acid hydrolysis conditions on the thermal, physical, and chemical properties of recycled particles intended for particleboard production. Particleboards were recycled using oxalic acid and ammonium chloride at different concentrations and reaction times at 122 °C. The thermal stability of the particles was determined by thermogravimetric analysis. Particle size distribution, particle morphology, nitrogen content, pH and acid/base buffer capacity were analyzed. The effect of the recycled particles on the urea-formaldehyde (UF) curing was assessed using differential scanning calorimetry and the gel time method. The recycled particles exhibited a higher thermal degradation beyond 200 °C, indicating their thermal stability for manufacturing new panels. The acid treatments did not damage the anatomical structure of the particles. The nitrogen content of recycled particles decreased by up to 90% when oxalic acid was used, compared to raw board particles. Recycled particles had a lower pH, a lower acid buffer capacity, and a higher base buffer capacity than those of raw board particles. The recycled particles did not significantly affect the peak polymerization temperature of the UF adhesive. However, some treatments affected the gel time of the adhesive. The results indicate that particleboards can be effectively recycled through acid hydrolysis, mainly with oxalic acid, which gives better results than hydrolysis using water alone. Oxalic acid showed increased selectivity in eliminating the cured UF adhesive, resulting in recycled particles suitable for manufacturing new panels.

Abstract: This study aimed to develop a mathematical model describing the thermal dissipation kinetics during the post-processing cooling phase of flat-pressed wood–polymer composites (FPWPC). The model elucidates the relationship between the composite's cooling time and the spatiotemporal temperature distribution across its thickness, as influenced by wood particle content, initial surface temperature, and bulk density. Analysis of the thermal profile in the core layer revealed three distinct phases: an initial temperature increase, a thermal peak, and a convective cooling phase. The results demonstrate that both the wood particle content and the initial surface temperature significantly affect the thermal dissipation rate. Higher initial surface temperatures (e.g., 200 °C) led to an initially accelerated cooling rate, followed by a deceleration phase. Composites with higher wood particle content (60%) exhibited slower cooling rates, which is attributed to the lower thermal conductivity of wood relative to the thermoplastic polymer matrix, resulting in greater thermal retention. Bulk density was also found to play a critical role in thermal management by influencing the composite’s specific heat capacity, thermal conductivity, and convective heat transfer efficiency. The proposed mathematical model offers potential for optimizing FPWPC manufacturing processes by enabling more precise control over cooling dynamics.

Abstract: The pine cone is an important forest product for the Portuguese economy. However, it is associated with environmental impacts, such as the generation of waste and the increased risk of forest fires. The objective of this research is to valorise waste from the production of Pinus pinaster Aiton in the form of natural dyes. The pine cone extracts were characterised in different alkaline solutions (1%, 5% and 10% NaOH) in order to evaluate the dyeing process on cotton knitwear, using the CIELab coordinates. The dyed samples were also subjected to light and water fastness tests. The extracts showed an increase in solids content with increasing alkalinity and a reduction in antioxidant content. The phenol content increased in the extract with 5% but decreased with the 10% concentration. All the dyes expressed a pink colour, but with different shades. About the L* coordinate (luminosity), the colours became lighter as the NaOH increased. n the a* coordinate, all the samples had a reddish colour and, in the b* coordinate, all the samples had a yellowish colour. About light and water fastness, all the samples lost colour, but in the water test it was not noticeable.

Abstract: This paper discusses how to make a diaper made with biodegradable materials. With the population increasing, pollution has become more prevalent in our current society, especially with waste that cannot be broken down and composted. Other companies that make diapers do not make use of environmentally friendly materials. Instead, they use gels and cloths that are not able to decompose. We used kapok fiber and bamboo cloth to tackle this problem and create environmentally safe and fully biodegradable diapers. We tested the diaper prototype dubbed the “Kaboo Diaper” using the rewet and absorbency test. The absorbency test showed that the diaper absorbed 323g of simulated urine. The rewet test showed that the diaper picked up 24g of water over time, passing industry standards. Showing the diapers to mothers contacted by the Health and Sanitation unit of Brgy. Oranbo deemed the prototype ready to use.

Abstract: The use of veneer composites as structural components in engineering requires special design. The dimensioning of laminated wood can be optimized by varying the wood species, veneer thickness, orientation, arrangement, number of single layers, and other factors. Composite properties can be calculated by suitable model approaches, such as the classical laminate theory. Thus, an optimization can be achieved. The present study verifies the adaptability of the classical laminate theory for veneer composites. Native veneer, adhesive-coated veneer, and solid wood were investigated as raw materials for the plywood layers. Mechanical properties were determined by tensile and shear tests and used as parameters to calculate the composite properties of the plywood. The plywood was bending tested, and the values obtained were compared with the calculations. The best prediction of the plywood properties is obtained by using the properties of the adhesive coated veneer as a single layer.

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With portable electronics and new-energy vehicles booming, the demand for high-performance energy storage devices has skyrocketed. Supercapacitor separators are thus vital. Traditional ones such as polyolefins and non-woven fabrics have limitations, while cellulose and its derivatives, with low cost, good hydrophilicity, and strong chemical stability, are potential alternatives. This study used regenerated cellulose Lyocell fibers. Through fiber treatment, refining, and in situ deposition, a composite regenerated cellulose separator (NFRC-Ba) with nano-barium sulfate was made. Its physical, ionic, and charge–discharge properties were tested. The results show that NFRC-Ba excels in terms of mechanical strength, porosity, hydrophilicity, and thermal stability. Compared with the commercial NKK30AC-100 separator, it has better ionic conductivity, better ion-transport ability, a higher specific capacitance, better capacitance retention, and good cycle durability. It also performs stably from -40°C to 100°C. With a simple and low-cost preparation process, NFRC-Ba could be a commercial separator for advanced supercapacitors.

Abstract:

Inferring forest properties is crucial for the timber industry, enabling efficient monitoring, predictive analysis, and optimized management. Nondestructive testing (NDT) methods have proven to be valuable tools for achieving these goals. Recent advancements in data analysis, driven by machine learning (ML) algorithms, have revolutionized this field. This study analyzed 492 eucalyptus trees, aged 3 to 7 years, planted in São Paulo, Brazil. Data from forest inventories were combined with results from ultrasound, drilling resistance, sclerometric impact, and penetration resistance tests. Seven machine learning algorithms were evaluated to compare their generalization capabilities with conventional statistical methods for predicting basic wood density. Among the models, Extreme Gradient Boosting (XGBoost) achieved the highest accuracy, with a coefficient of determination (R²) of 89% and a root mean square error (RMSE) of 10.6 kg·m⁻³. In contrast, the conventional statistical model, using the same parameters, yielded an R² of 33% and an RMSE of 26.4 kg·m⁻³. These findings highlight the superior performance of machine learning in nondestructive inference of wood properties, paving the way for its broader application in forest management and the timber industry.

Abstract:

Wool fibers have long been used in home textiles and clothing, but their future looks even more promising with the growing consumer demand for natural, renewable, and sustainable materials. Beyond traditional clothing, wool is gaining increasing attention in the field of technical textiles due to its unique properties that make it suitable for a wide range of applications. As a natural and renewable fiber, wool offers benefits including tremendous moisture absorption, temperature law, and flame resistance, which make it a perfect material for technical textiles. In this study, two styles of Moroccan wool (Sardi and Timahdite), sourced from one-of-a-kind areas become accrued to explore their bodily and chemical homes and to investigate their capacity use within the manufacturing of nonwoven textiles for technical applications. Various analyses were carried out, inclusive of Fourier-remodel infrared spectroscopy and the Optical Fiber Diameter Analyzer, together with numerous check techniques based totally on global standards. These tests evaluated parameters which include grease content material, alkali content, acid content, solubility in alkali, and tensile strength. The results showed that Timahdite wool is the most suitable for nonwovens, way to its fineness and excessive absorbency compared with the Sardi wool.

Abstract: An advanced, eco-friendly, and fully bio-based flame retardant (FR) system has been created and applied to the cellulose structure of the cotton fabric through a layer-by-layer coating method. This study examines the flame-retardant mechanism of protein based and phosphorus containing coatings to improve fire resistance. During combustion, the phosphate groups (-PO₄²⁻) in phosphorus containing flame retardant layer interact with the amino groups (-NH₂) of protein, forming ester bonds which results in generation of crosslinked network between the amino groups and the phosphate groups. This structure greatly enhances the thermal stability of the residual char, hence, improving fire resistance. Tests such as the cone calorimeter and flammability tests show significant improvements in fire safety, including lower peak heat release rates, reduced smoke production, and higher char residue, all contributing to better flame-retardant performance. pHRR, THR and TSP of the flame-retarded cotton fabric demonstrated 25, 54 and 72% reduction, respectively. These findings suggest that LbL-assembled protein-phosphorus based coatings provide a promising, sustainable solution for creating efficient flame-retardant materials.

Abstract: This study evaluates the chemical, physical, mechanical, and biological properties of untreated and heat-treated Cryptomeria japonica wood from the Azores, Portugal. Heat treatment was performed at 212°C for 2 hours following the Thermo-D class protocol. Chemical analysis revealed an increase in ethanol extractives and lignin content after heat treatment, attributed to hemicellulose degradation and condensation reactions. Dimensional stability improved significantly, as indicated by reduced swelling coefficients and higher anti-swelling efficiency (ASE), particularly in the tangential direction. Heat-treated wood demonstrated reduced water absorption and increased density, enhancing its suitability for applications requiring dimensional stability. Mechanical tests showed a decrease in bending strength by 19.6% but an increase in the modulus of elasticity (MOE) by 49%, reflecting changes in the wood's structural integrity. Surface analysis revealed significant color changes, with darkening, reddening and yellowing, aligning with trends observed in other heat-treated woods. Biological durability tests indicated that both untreated and treated samples were susceptible to subterranean termite attack, although heat-treated wood exhibited a higher termite mortality rate, suggesting potential long-term advantages. This study highlights the impact of heat treatment on Cryptomeria japonica wood, emphasizing its potential for enhanced stability and durability in various applications.

Abstract: In this study, we explored the structural and chemical modifications of cellulose fibres subjected to chemical and mechanical treatments through an innovative analytical approach. We employed photoacoustic spectroscopy (PAS) and reversed double-beam photoacoustic spectroscopy (RDB-PAS) to examine the morphological changes and the chemical integrity of the treated fibres. The methodology provided enhanced sensitivity and specificity in detecting subtle alterations in the treated cellulose structure. Additionally, we applied Coifman wavelet transformation to the PAS signals, which facilitated a refined analysis of the spectral features indicative of chemical and mechanical modifications at a molecular level. This advanced signal processing technique allowed for a detailed decomposition of the PAS signals, revealing hidden characteristics that are typically overshadowed in raw data analyses. Further, we utilized the concept of energy trap distribution to interpret the wavelet-transformed data, providing insights into the distribution and density of energy states within the fibres. Our results indicated significant differences in the energy trap spectra between untreated and treated fibres, reflecting the impact of chemical and mechanical treatments on the fibre’s physical properties. The combination of these sophisticated analytical techniques elucidated the complex interplay between mechanical and chemical treatments and their effects on the structural integrity and chemical composition of cellulose fibres.