Search Results (62)

Nature-inspired material design has gained increasing attention in the development of sustainable biocomposites for applications requiring the integration of structural performance and functional efficiency. However, many lignocellulosic composites still depend on synthetic binders and fail to achieve a strong effective interaction between constituents, resulting in suboptimal mechanical integrity and thermal behavior while limiting their environmental advantages. This study aims to develop binderless biocomposite panels from Hevea brasiliensis-derived spent mushroom substrate (SMS) and Elaeis guineensis empty fruit bunch (EFB) fibers, emphasizing the synergistic interaction between components for energy-efficient building applications. Chemical characterization revealed complementary roles, with EFB contributing a high cellulose content (57.60%) for reinforcement and SMS providing a higher lignin content (30.51%) for enhanced rigidity and natural binding. Panels were fabricated via hot pressing at a target density of 0.8 g/cm³ without additives. Mechanical properties were evaluated through specific flexural, tensile, internal bond, and impact testing, while thermal conductivity and thickness swelling were used to assess functional performance. The 60% SMS with 40% EFB composition exhibited optimal performance, achieving a specific flexural strength of 20.26 MPa, a flexural modulus of 1943.76 MPa, tensile strength of 6.12 MPa, an internal bond strength of 2.06 MPa, an impact strength of 15.35 kJ/m², a thickness swelling of 44.80%, and a thermal conductivity of 0.234 W/m.K. These results demonstrate that the combined effect of SMS and EFB in binderless biocomposites derived from secondary products offers a promising biomimetic pathway for designing recyclable, high-performance materials suitable for sustainable and energy-efficient construction systems. Full article

Tree bark, an abundant by-product of the timber industry, represents a promising feedstock for sustainable construction. This study investigates the thickness swelling, water absorption, hygroscopicity and mechanical (compressive strength) properties of insulation panels produced from hardwood bark (Tilia spp. and Robinia pseudoacacia) via hydromechanical treatment and a wet-forming process. The panels were produced without added adhesives, relying on the formation of hydrogen bonds during the drying phase to ensure structural integrity. Both bark-based insulation boards (thermal conductivity coefficient 0.055–0.057 W/m·K) showed similar hygroscopic behavior, reaching equilibrium moisture contents of max. 25% at 93.9% RH. Water absorption after 24 h immersion was highly material-dependent; Tilia-based panels showed 57.11 ± 5.81%, and Robinia-based panels 320.61 ± 11.34%. Thickness swelling remained low (max. 6% for Robinia), showing significant orthotropic anisotropy. At 10% compressive strain, the Tilia and Robinia bark-based panels showed compressive strengths of 188 ± 14.6 kPa and 298 ± 18.1 kPa, accordingly. These findings demonstrate that hardwood bark can be successfully valorized into high-performance, binderless insulation, supporting circular economic strategies. Full article

This study addresses the urgent need for sustainable alternatives to single-use plastics by developing biodegradable composites from peach and apple processing waste employing hot compression molding. Utilizing a definitive screening design, the impact of the process variables, including recipe composition, grinding size, pressure, temperature, and holding time, on the physical (including water resistance) and mechanical properties of the composites was systematically evaluated. Physicochemical and thermal analyses of the dried by-products indicated that processing temperatures below 150 °C prevent the degradation of lignocellulosic constituents. The results demonstrated that increasing both the molding pressure and holding time decreased the composite thickness, while enhancing the stiffness and flexural strength, with modulus of elasticity values exceeding 1000 MPa under optimal conditions. Higher molding temperatures reduced water absorption and diffusivity, particularly in lignin-rich composites, by promoting lignin softening and particle consolidation, resulting in denser structures with limited moisture transport. Biodegradability was assessed through soil burial tests over 200 days, revealing a weight loss ranging from 54.2% to 90.7% among samples, with apple-based composites exhibiting greater degradation compared to peach-based ones. Overall, the study highlights the development of a “green composite” formulation inspired by biomimetic principles, exploiting the natural self-bonding capacity of lignocellulosic biomass, where two different-in-composition biowastes are combined to produce a plastic-free composite material with possible applications in the foodservice industry. Full article

The development of sustainable thermal insulation materials is crucial for reducing the environmental impact of the construction sector. This study investigates the potential of binderless insulation boards made from rapeseed fibers, utilizing the natural adhesive properties of lignin. The effects of fiber fineness and processing temperature (160 °C and 180 °C) on basic physical, hygric and thermal properties were examined. The influence of temperature on thermal conductivity was minimal, while higher temperature slightly reduced moisture content and swelling. Finer fibers and higher temperature increased the water vapor diffusion resistance factor. Microscopy and thermal analyses confirmed sufficient lignin softening and fiber bonding at 160 °C, whereas higher temperatures caused partial fiber degradation. Overall, the results demonstrate that rapeseed straw boards provide a sustainable and vapor-permeable alternative for roof and general insulation applications, with processing conditions and fiber fineness influencing hygric properties more than thermal performance. Full article

The transition toward sustainable panel technologies is driving intensive research on binderless boards and self-bonded lignocellulosic composites. Particleboard, an engineered wood composite made by hot pressing wood particles with synthetic adhesives, is among the most widely produced wood-based panels due to cost-effectiveness and versatility. However, pressure on forest-derived raw materials and concern over formaldehyde emissions are accelerating the search for renewable resources and greener routes. Residues and underutilized materials from agro-industrial, food, and forestry sectors (such as cereal straws, sugarcane bagasse, brewer’s spent grain, and fruit-processing by-products) offer a sustainable alternative, enabling waste valorization, lowering environmental burdens, and supporting circular bioeconomy models. Binderless boards, produced without adhesives, exploit natural bonding among lignocellulosic components, including lignin softening, thermoplasticization, and covalent crosslinking during hot pressing. This review adopts a complex network approach to systematically map and analyze the scientific landscape of binderless board production. Using citation-based networks from curated seed papers and their first- and second-degree neighbors, we identify thematic clusters, with cluster “A” as the research core. The examination of this cluster, complemented by word-cloud analysis of titles and abstracts, highlights prevalent raw materials and key research lines, like raw-material sources and lignocellulosic composition, processing parameters, and pretreatment strategies. Based on these findings, brewer’s spent grain is selected as a representative case study for cost analysis. This approach synthesizes the state of the art and reveals emerging directions, research gaps, and influential works, providing a data-driven foundation for advancing self-bonded lignocellulosic composites. Full article

This paper contributes to the knowledge of binderless tungsten carbide (WC), which attracts the attention of many engineers and scientists for its superior properties, but its application is limited due to difficulties with the consolidation of initial powders. In the present study, the microstructure and mechanical properties of binderless WC, sintered with the electroconsolidation technique from the initial powder of a grain size of 100–200 nm, were investigated. The material was compared with nWC sintered with the same method from a nanopowder with particles of size ca. 70 nm. The binderless μWC demonstrated hardness of HV = 30.06 ± 0.09 GPa, which is almost 14% higher than that of nWC, but its fracture toughness was lower (K_IC = 6.59 ± 0.46 MPa·m^1/2 under 1 kg load). These differences can be attributed to the improved homogeneity of the μWC microstructure, where no large agglomerates appeared to be present in nWC. The measured plastic properties, with no signs of brittle fracture, further confirm the applicability of the binderless WC under contact stress conditions. Full article

As a kind of novel binderless composite, WC-cBN-SiC_w composite possesses significant potential value in special sealing components and high-pressure medium nozzles. However, under severe wear and corrosion conditions, the surface defects caused by friction will be accelerated to become a crack source in aggressive environments. Because of the intrinsic brittleness of WC cemented carbide, its strength is extremely sensitive to local surface damage. Therefore, the influence of applied load (10 N, 20 N, 40 N and 60 N) on its tribological behavior was studied. Meanwhile, the impact of corrosion resistance of WC-cBN-SiC_w composite on surface damage induced by friction was further investigated. Full article

Bamboo, as a rapidly renewable biomass material, has garnered significant attention in contemporary research due to its cost effectiveness as a viable source for supercapacitor electrode materials. However, untreated bamboo as an electrode material often leads to poor connectivity and uneven pore distribution. This study introduces a novel approach by using bamboo-derived biological carbon as a conductive substrate, subjecting it to carbonization through white-rot fungal pretreatment to enhance the pore structure and then loading it with nano-MnO₂ sheets via a hydrothermal process. The result is a binderless, self-supporting supercapacitor electrode material, denoted as MnO₂/hyphae/bamboo-derived carbon (HBC-2M). When compared to untreated bamboo carbon (HBC-0), HBC-2M exhibits an increased number of energy storage sites, enhanced electrolyte ion transport channels, and superior electrochemical performance. HBC-2M achieves a maximum mass-specific capacitance of 133.69 F·g⁻¹ and a maximum area-specific capacitance of 2367.95 mF·cm⁻² and retains approximately 87.46% of its capacitance after 2000 cycles. This research suggests a promising future for bamboo charcoal in supercapacitors. Full article

Barro Alto processes nickel laterite ore using rotary kilns and six-in-line rectangular electric arc furnaces. This study evaluated the briquetting of ferronickel ore to reduce kiln fines, improve furnace charge permeability, and enhance process safety. Binderless briquettes were produced from screened ore at two size fractions (−6.3 mm and −12.5 mm), with moisture contents of 16% and 24%, cured under closed and open conditions. The physical and metallurgical properties of the briquettes were assessed using ISO standard tests. The results confirmed successful agglomeration of the ore into binderless briquettes. Screening the run-of-mine (ROM) ore improved the feed quality, increasing the NiO grade from 2.0% to 2.2% in the −6.3 mm fraction. The briquettes from the −6.3 mm ore at 16% moisture exhibited the highest green strength (559 N). Higher moisture content reduced the briquette strength and increased both the reduction disintegration and decrepitation indices. The decrepitation index increased from 0.33% to 0.61% for the −6.3 mm briquettes when the moisture increased from 16% to 24%. The reduction levels were 33.4% and 39.2% for −6.3 mm and −12.5 mm briquettes with 16% moisture, respectively. This study concludes that optimal performance was achieved using −6.3 mm ore, 16% moisture, and open curing, thereby balancing reduction efficiency and mechanical stability. Full article

Effective sound absorption materials are essential for mitigating noise pollution in urban and industrial environments, which pose serious health risks to humans. This work develops a hierarchical natural fibre binderless composite based on porous luffa, modified with localised cellulose nanocrystals (CNCs), for application in acoustic panels. The impedance tube approach was employed to systematically evaluate sound absorption performance across a range of frequencies. Adding 3 wt.% and 7 wt.% CNCs to the porous luffa structure improved its sound absorption, especially in mid-to-high frequency areas. The binderless luffa panels with 3% CNC panels exhibited the most balanced performance across various thicknesses, while 7% CNC–luffa panels demonstrated excellent sound absorption averages across all frequency ranges, although increased rigidity and reflective tendencies were observed. The nano-modification successfully maintained the sound absorption coefficient with reduced panel thickness. This study establishes CNC-modified luffa composites as a sustainable and efficient alternative to conventional acoustic materials, leveraging renewable resources and lightweight characteristics. These findings highlight the potential of CNC-luffa composites for noise mitigation, paving the way for environmentally conscious acoustic solutions. Full article

Increasing the flame retardancy of lignocellulosic materials such as Miscanthus × giganteus can effectively enable their wide use. This study examines the fireproofing process of Miscanthus particles using an eco-friendly process by grafting phytic acid and urea in aqueous solution. Miscanthus particles underwent a steam explosion step before being grafted. Fireproof binderless particle panels were manufactured from miscanthus particles with or without adding olive pomace by hot-pressing. The effect of the steam explosion and/or the flame-retardant treatment on the morphology, chemical composition and thermal stability of the particles, as well as the thermal stability of the panels, was investigated. The results showed that water impregnation followed by a steam explosion at 210 °C for 8 min resulted in particles that were rich in lignin and more homogeneous in size (length and width). Fireproof particles were produced with relatively low P and N contents. The flame retardancy of the binderless particle panels was significantly improved when using miscanthus particles treated with phytic acid and urea, as shown by a reduced heat release (HRR) and an increased time-to-ignition. However, the presence of olive pomace significantly decreased the flame retardancy of the panels. Binderless particle panels prepared from grafted miscanthus particles showed the best fire properties and are considered fireproof. Full article

Due to its low cost, natural abundance, non-toxicity, and high theoretical capacitance, cobalt oxide (CoO) stands as a promising candidate electrode material for supercapacitors. In this study, binder-less molybdenum doped CoO (Mo@CoO) integrated electrodes were one-step fabricated using a simple electric discharge corrosion (EDC) method. This EDC method enables the direct synthesis of Mo@CoO active materials with oxygen vacancy on cobalt substrates, without any pre-made templates, conductive additives, or chemicals. Most importantly, the EDC method enables precise control over the discharge processing parameter of pulse width, which facilitates tailoring the surface morphologies of the as-prepared Mo@CoO active materials. It was found that the fabricated Mo@CoO based symmetric supercapacitor prepared by a pulse width of 24 μs (Mo@CoO-SCs24) achieved a maximum areal capacitance 36.0 mF cm⁻² (0.15 mA cm⁻²), which is 1.83 and 1.97 times higher than that of Mo@CoO-SCs12 and Mo@CoO-SCs36. Moreover, the Mo@CoO-SCs24 devices could be worked at 10 V s⁻¹, which demonstrates their fast charge/discharge characteristic. These results demonstrated the significant potential of the EDC strategy for efficiency fabricating various metal oxide binder-less integrated electrodes for various applications, like supercapacitors, batteries and sensors. Full article

Currently, wood-based panels are mainly made from wood and adhesives containing formaldehyde. With the growing demand for raw materials and increasing concern for human health, the use of residues from annual crops to manufacture binder-free biodegradable biomass boards has attracted increasing interest. The aim of this study was to develop a biodegradable bio-board without any adhesives using eggplant straw fibers. The bio-boards were produced via simple mechanical refinement of eggplant straw fibers and were formed under pressures of 2.0 MPa, 3.5 MPa, 5.0 MPa, 6.5 MPa, and 8.0 MPa. The mechanical properties and dimensional stability of the manufactured bio-boards were evaluated. With increasing applied pressure, the bending rupture stress of the bio-boards increased from 27.69 MPa to 45.29 MPa, the tensile rupture stress varied from 12.45 MPa to 24.62 MPa, the water absorption decreased from 91.45% to 88.29%, and the contact angle increased from 89.67° to 90.45°. The bio-boards were subjected to morphological analysis (SEM) and porosity and crystallinity measurements (XRD), and the results indicated that the water absorption of the bio-boards was due to a combination of porosity and crystallinity. The results showed that eggplant straw is suitable for manufacturing bio-boards. Full article

High-purity, superhard, binderless polycrystalline cubic boron nitride (BL-PCBN) was obtained by direct hBN to cBN transformation in a toroid-type high-pressure apparatus at a pressure of 8.0 GPa and temperature of 2250 °C (HPHT-DCS; high-pressure, high-temperature direct conversion sintering). X-ray diffraction analysis revealed a prominent [111] axial texture in the sintered material when the axis was oriented perpendicular to the end surface of the sample. Vickers hardness tests conducted at a load of 49 N showed that BL-PCBN possessed an exceptional hardness value of 63.4 GPa. Finally, cutting tools made of BL-PCBN and SN-PCBN (Si₃N₄-doped cBN-based composite) reference materials were tested during the turning of a cemented tungsten carbide workpiece. The results of the cutting tests demonstrated that the wear resistance of the BL-PCBN material obtained with the HPHT-DCS process is 1.5–1.9 times higher compared to the conventional SN-PCBN material, suggesting its significant potential for industrial application. Full article

The building and construction sector is the largest emitter of greenhouse gases, accounting for 37% of global emissions. The production and use of materials such as cement, steel, and aluminum contribute significantly to this carbon footprint. Utilizing valorized agricultural by-products, such as hemp shiv and sunflower pith, in construction can enhance the insulating properties of materials and reduce their environmental impact by capturing CO₂. Additionally, during the formulation process, molecules such as polyphenols and sugars are released, depending on process parameters like pH and temperature. In some cases, these releases can cause issues, such as delaying the hardening of agro-based concrete or serving as binding agents in binderless particle boards. This study focuses on the molecules released during the processing of these materials, with particular attention to the effects of pH and temperature, and the modifications to the plant particles resulting from these conditions. Physical, chemical, and morphological analyses were conducted on the treated hemp shiv particles (HS1 and HS2). No physical or morphological differences were observed between the samples. However, chemical differences, particularly in the lignin and soluble compound content, were noted and were linked to the release of plant substances during the process. Full article