Search Results (164)

This research aimed to evaluate the biological resistance to xylophagous organisms and the dimensional stability related to water absorption in plastic wood panels manufactured by compression molding and produced with pine wood and recycled thermoplastics. The wood–plastic composites (WPCs) were prepared from 50% pine sawdust and 50% recycled plastics (polyethylene terephthalate-PET, high-density polyethylene-HDPE, and polypropylene-PP). The thickness swelling test was carried out by immersing of the WPC samples in water at room temperature (25–30 °C) and evaluating the total change in WPC thickness after 1500 h (≈9 weeks or two months). In addition, the coefficient of initial swelling was evaluated to verify the variability of the swelling. For the biological resistance evaluation of the WPCs, tests were carried out with soil or arboreal termites (Nasutitermes corniger) and drywood termites (Cryptotermes brevis). The WPC loss of mass and termite mortality were evaluated. The use of PP promoted the best response to thickness swelling. The simple mathematical model adopted offers real predictions to evaluate the thickness of the swelling of the compounds in a given time. For some variables there were no statistical differences. It was shown that treatment 3 (T3) presented visual damage values between 0.4 for drywood termites and 9.4 for soil termites, in addition to 26% termite mortality, represented by the lowest survival time of 12 days. The developed treatments have resistance to termite attacks; these properties can be an important starting point for its use on a larger scale by the panel industries. Full article

The natural variability and moisture sensitivity of bamboo limit its widespread use in construction applications. To address these challenges, densification and delignification processes have emerged as promising modification techniques. Densification and delignification processes can lead to significant improvements in the physical, mechanical, and chemical properties of solid wood. In this study, a two-step process of delignification and densification was carried out on Dendrocalamus asper bamboo specimens. The objective was to assess whether the optimized parameters of densification for natural bamboo on an open pressing system can be transferred for delignified bamboo. Delignification was achieved using an alkali solution (NaOH and Na₂SO₃) with two different temperature settings (25 °C or 100 °C). The pre-treated samples were dried in one of the two different conditions, either at 100 °C for 24 h or 25 °C for 30 days, resulting in four different groups with an average moisture content ranging from 7 to 10%. The samples were densified to 50% of their original thickness through an open thermo-mechanical press system at 160 °C with a compression rate of 6.7 mm/min and compared to densified bamboo without delignification (reference). The compression stress required to achieve a 50% degree of densification was evaluated, with untreated samples exhibiting an average value close to 17 MPa. Following treatment, the compression stress ranged from 7 to 13.4 MPa, indicating that the exposure to a high pH solution facilitates the densification process. However, a reduction in flexural properties (MOR, LOP, and MOE) was observed on the alkali-treated samples after a three-point bending test. Physical properties (water absorption and thickness swelling) were not altered after delignification. These findings demonstrate that the direct application of a densification process optimized for natural bamboo is not fully effective for chemically modified bamboo, highlighting the need for adjustments. Delignified bamboo showed an increase in free space after chemical treatment, which should be further densified under higher degrees. Full article

The growing volume of plastic waste from end-of-life vehicles presents environmental concerns, driving efforts to integrate recycled plastics. This study investigates the possibility of using recycled plastic from automotive parts (painted and unpainted bumpers, fuel tanks) as a 10% filler in the core layer of three-layer particleboards (P) and evaluates its impact on physical properties (water absorption—WA and thickness swelling—TS), mechanical properties (internal bonding strength—IB, modulus of rupture—MOR, modulus of elasticity—MOE and screw driving torque—SDT) and volatile organic compounds—VOC emissions. The boards were produced using conventional hot-pressing technology and analyzed according to applicable standards. Based on the results, the density of the reference (P) was 0.72 g·cm⁻³, while wood–plastic composites ranged from 0.70 g·cm⁻³ to 0.72 g·cm⁻³. After 24 h, WA reached 40% for reference (P) and from 36.9% (for (P) containing unpainted bumpers) to 41.9% (for (P) containing fuel tanks). TS reached 18% for (P) and from 16.8% (for (P) containing unpainted bumpers and fuel tanks) to 18.1% (for (P) containing painted bumpers). Plastic is a hydrophobic material and it is assumed that by increasing the proportion of plastic filler in the particleboards, the WA and TS of prepared boards will decrease. From the point of view of mechanical properties, values for (P) containing plastic filler were slightly lower compared to reference (P). The lowest value of IB (0.39 MPa) were reached for (P) containing painted bumpers. Plastic surface treatment could interfere with adhesion between the plastic and adhesive, weakening the bond in the core layer. For this reason, is preferable to use unpainted fillers, which provide better adhesive properties and higher structural integrity. VOC emissions from wood components consisted primarily of monoterpenes such as α-pinene, 3-carene and limonene. Adding 10% plastic to the particleboard did not increase overall VOC emissions. On the other hand, combining wood and plastic particles resulted in a reduction in overall VOC emissions. The findings confirm that recycled automotive plastics can be effectively incorporated into particleboards, maintaining standard performance while reducing reliance on virgin wood materials, making them a viable and sustainable alternative for furniture and interior applications. Full article

The construction sector’s increasing eco-consciousness is driving the need for higher-performance wood-based engineered products from underutilized timber resources, such as small-diameter trees from hazardous fuel treatments of our forests. Strand-based products, including oriented strand board (OSB) and lumber (OSL), are widely used. However, hot-pressing during their manufacturing generates approximately 10% waste, which includes a substantial amount of resinated strands that are landfilled. The huge potential of using strand-based products has led to many studies and growing interest in strand-based three-dimensional sandwich panels that can be used as wall, floor, or roofing panels. As the market grows, understanding the recyclability of these resinated strands becomes crucial. This study investigates the feasibility of using re-resinated waste strands that were collected during lab-scale production of strand-based panels. Results demonstrate significant improvements in dimensional stability, mechanical properties, and fire resistance. Specifically, recycling increased internal bond strength, flexural strength, time to ignition, time to flameout, mass loss, and time to peak heat release rate by 107%, 44%, 58%, 35%, 51%, and 27%, respectively, and helped decrease water absorption and thickness swell by 51% and 58%, respectively. Full article

This paper evaluates the performance of composites made from date palm (Phoenix dactylifera L.) midribs reinforced with carbon fiber. Two types of adhesives—unsaturated polyester and epoxy resin—were used as binder for the experimental panels. The physical properties and mechanical strength of the composites, as a function of fiber types, lamination configuration, as well as adhesive types, were determined. The density levels of the panels made using epoxy and unsaturated polyester resin were found to be 1103 kg/m³ and 1133 kg/m³, respectively. Panels made using polyester adhesive had 6.05% and 3.98% for water absorption and thickness swelling values, respectively. Corresponding values of 3.09% and 6.35% were found for the panels made using epoxy resin. Mechanical properties of the samples revealed that carbon fiber-reinforced epoxy hybrids offer superior mechanical performance, whereas polyester-based hybrids may be more suitable for impact-resistant applications. Stereo-microscopy and vertical density profile (VDP) analysis of the panels resulted in variations in layer adhesion and density distribution. Based on the findings in this work, carbon fiber-reinforced epoxy-bonded hybrid panels exhibited superior mechanical properties, while those panels made using polyester-based binder would be more suitable where impact resistance is desired. The combination of date palm fibers and carbon fiber presents significant potential for sustainable applications, offering a balance of strength and durability. Full article

In the search for eco-friendly and resource-efficient alternatives to conventional building materials, agricultural residues are gaining increasing attention as reinforcements in cement-based composites. This study investigates the potential of walnut shell particles (WSPs), a lignocellulosic bio-product, as a sustainable reinforcing agent in walnut shell cement boards (WSCBs). Using super white cement (SWC) as a binder, boards were manufactured with WSP content ranging from 10% to 50% by weight, targeting a density of 1300 kg/m³, a 10 mm thickness, and a water-to-cement ratio of 0.6:1. The mixtures were cold-pressed at ambient temperature using a hydraulic press at 3 MPa for 24 h, followed by curing for 28 days under ambient conditions. Physical properties such as density, water absorption, and thickness swelling were assessed, along with mechanical performance, through flexural testing. Fracture surfaces and internal microstructures were examined using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). Functional groups and chemical reactions were monitored using FTIR, while thermal analysis (TGA and DSC), as well as measurements of thermal conductivity and resistance, provided comprehensive insights into the thermal behavior, insulating performance, and energy efficiency potential of the boards. Results demonstrate that the board with 30% WSP exhibited an optimal balance of physical and mechanical properties, achieving a 24 h water absorption of 14.05% and a modulus of rupture (MOR) of 6.53 MPa, making it suitable for non-structural applications. The board with 50% WSP exhibited the best thermal insulation performance, with a low thermal conductivity of 0.079 W/m·K. These findings highlight the potential of recycled agricultural materials in enhancing building materials’ performance, contributing to sustainable, eco-friendly construction practices. Full article

The aim of the article was to test new types of rubber-containing particleboards created from waste materials, which positively contributes to environmental protection, saving primary resources and reducing production costs. This article focuses on the study of three-layer particleboards made from wood particles (spruce non-treated beams) and waste rubber granulates (tires, mixture of seals and carpets, internal flammable cables, external non-flammable cables). Urea–formaldehyde glue, melamine–formaldehyde glue, paraffin emulsion, and ammonium nitrate were used as a binders and excipients in the manufacturing of particleboards. In the core layer of each particleboard, 10% of the weight was made up of rubber granulate. Physical properties (density, water absorption, thickness swelling) and mechanical properties (internal bonding strength, modulus of rupture, modulus of elasticity, screw driving torque) were assessed from this perspective using current EN technical standards. According to the findings, the average densities of all particleboards were comparable to each other in a range from 0.692 to 0.704 g·cm⁻³. The lowest average water absorption and thickness swelling reached particleboards containing 10% of waste internal flammable cables, namely 32.79% for water absorption and 13.21% for thickness swelling. The highest average internal bonding strength reached particleboards without rubber filler and particleboards containing 10% of waste external non-flammable cables, namely 0.52 MPa for both types. The highest average modulus of rupture reached particleboards without rubber filler, namely 12.44 MPa. The highest average modulus of elasticity reached particleboards containing 10% of waste internal flammable cables, namely 2206.29 MPa, and the highest screw driving torque reached particleboards without rubber filler, namely 0.46 N·m for seating torque and 1.44 N·m for stripping torque. The results show that particleboards containing waste external non-flammable cables and particleboards containing waste internal flammable cables achieved comparable results to particleboards without rubber filler, which provides a good basis for a new way of utilizing this type of waste in the form of producing new wood–rubber composites. Full article

The push for sustainability in all facets of manufacturing has led to an increased interest in biomass as an alternative to non-renewable materials. Hemp bast fiber mats were produced from a bacterial retting process, named BFM, as the fiber reinforcement. The objective of this study was to evaluate the feasibility of laminating BFM with polylactic acid (PLA) for a composite panel product. Since both BFM and PLA are biodegradable, the resulting BFM-PLA composites will be 100% biodegradable. PLA pallets were processed into thin polymer sheets which served as the matrix. The BFM and PLA plates were laminated in five layers and compression-molded into composite panels. Experiments were conducted on the three BFM-to-PLA ratios (35/65, 45/55, and 50/50). Mechanical properties (tensile and bending properties) and physical properties (thickness swell and water absorption) were tested and compared to the currently commercial sheet molding compound (SMC) from fiber glass. The thermal behavior of the BFM/PLA composites was characterized using dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). The developed BFM/PLA composite product is a sustainable alternative to existing synthetical fiber-reinforced polymer (FRP) that is biodegradable in landfill at the end of life. Full article

Surface layer thermal modification (SLTM) not only improves the dimensional stability of wood but also effectively shortens production time. However, limited research has been conducted on how treatment conditions influence the properties of SLTM wood and energy consumption during the production process. This study compared the physical properties of SLTM wood with conventional thermally modified (CoTM) wood treated at 185 °C, 200 °C, and 215 °C, as well as the energy consumption during processing. Samples were subjected to SLTM at three temperatures (185 °C, 200 °C, and 215 °C) two times (2 h and 3 h) and two target surface layer thicknesses (6 mm and 12 mm). The results showed SLTM improved dimensional stability, with the anti-swelling efficiency (ASE) after water absorption increasing by a maximum of 2.4 times compared to CoTM185-2h. Increases in treatment temperature, time, and target surface layer thickness all contributed to enhanced ASE. At 96% relative humidity, SLTM wood samples exhibited lower equilibrium moisture content (16.6% to 19.2%) than CoTM185-2h (19.5%). SLTM also reduced the total treatment time by 1.9 h to 10.8 h compared to CoTM treatments. SLTM demonstrated energy savings ranging from 215 kW∙h to 1567 kW∙h, resulting in a reduction in CO₂ emissions by 73 kg to 729 kg per 1 m³ of processed wood. These findings suggest that SLTM provides a promising strategy for the energy-efficient utilization of plantation wood. Full article

The green transition trend in the wood-based panel industry aims to reduce environmental impact and waste production, and it is a viable approach to meet the increasing global demand for wood and wood-based materials as roundwood availability decreases, necessitating the development of composite products as alternatives to non-wood lignocellulosic raw materials. As a result, the purpose of this study is to examine and assess the physical, mechanical, and acoustic properties of particleboard manufactured from non-wood lignocellulosic biomass. The core layer was composed of non-wood lignocelluloses (banana stem, rice straw, coconut fiber, sugarcane bagasse, and fibrous vascular bundles (FVB) from snakefruit fronds), whereas the surface was made of belangke bamboo (Gigantochloa pruriens) and wood. The chemical characteristics, fiber dimensions and derivatives, and contact angles of non-wood lignocellulosic materials were investigated. The contact angle, which ranged from 44.57 to 62.37 degrees, was measured to determine the wettability of these materials toward adhesives. Hybrid particleboard (HPb) or sandwich particleboard (SPb) samples of 25 cm × 25 cm with a target density of 0.75 g/cm³ and a thickness of 1 cm were manufactured using 7% isocyanate adhesive (based on raw material oven dry weight). The physical parameters of the particleboard, including density, water content, water absorption (WA), and thickness swelling (TS), ranged from 0.47 to 0.79 g/cm³, 6.57 to 13.78%, 16.46 to 103.51%, and 3.38 to 39.91%, respectively. Furthermore, the mechanical properties of the particleboard, including the modulus of elasticity (MOE), bending strength (MOR), and internal bond strength (IB), varied from 0.39 to 7.34 GPa, 6.52 to 87.79 MPa, and 0.03 to 0.69 MPa, respectively. On the basis of these findings, the use of non-wood lignocellulosic raw materials represents a viable alternative for the production of high-performance particleboard. Full article

Chicken eggshells are a useful waste that may be used somewhere rather than being placed in landfills. They are created in poultry hatcheries, the food sector (making pasta, cakes, and egg products), or our homes. In this project, this study aimed to investigate the possibility of producing plywood using a filler in the gluing process in the form of ground eggshells. This study includes the production of plywood with 0, 1, 5, 10, and 20 parts by weight (pbw) of eggshell filler (called E0, E1, E5, E10, and E20, respectively) and one reference variant with rye flour (10 pbw; hereafter called REF10). This research also includes investigating the produced panels’ selected physical and mechanical properties. The results show that chicken eggshells can be used to produce plywood if the right amount of filler is chosen to improve specific mechanical and physical properties. Promising properties were obtained in the determination of the modulus of elasticity under bending (MOE) for samples E5 (11,310 N mm⁻²) and E10 (11,394 N mm⁻²) and modulus of rupture (MOR) for sample E5 (130 N mm⁻²). The results for the internal bond (IB) show that the addition of 5 pbw of filler in the form of ground shells shows good properties with as much as 5.23 N mm⁻², but still, the reference sample with the addition of filler in the form of rye flour has higher results of 6.22 N mm⁻². In the test of water absorption of fillers, the absorption of calcium carbonate is 207% and is lower than that of rye flour (224%). For the swelling thickness results, the E10 sample showed the weakest results of 7.6% after 2 h and 8.9% swelling after 24 h. Full article

This study investigates the effects of suberic acid residue (SAR) additions on structural single-layer particleboard (like the P5 type, according to EN 312) properties, specifically the water absorption (WA), thickness swelling (TS), modulus of rupture (MOR), modulus of elasticity (MOE), screw withdrawal resistance (SWR), and internal bond (IB) strength. The results indicate that finer SAR fractions (1/0.25 and 2/1) reduce the WA after 2 h of soaking, while larger fractions increase the WA after 24 h, with only the smallest fraction meeting the TS standards. The MOR values (18.5–19.6 N mm⁻²) and MOE (3627–3811 N mm⁻²) remain largely unaffected by SAR additions, while the SWR shows minimal variation across various SAR fractions (203–209 N mm⁻¹). The IB strength improves with SAR additions, peaking at 2.10 N mm⁻² for the 5/2 fraction, though slightly decreasing with the largest fraction (8/5). A density analysis reveals an increased surface density with finer SAR fractions, benefiting the surface strength but reducing the core uniformity with larger fractions. These findings suggest that SAR-enhanced particleboards could be valuable in applications requiring moisture resistance, such as bathrooms, kitchens, and exterior cladding. Further research should explore optimizing the SAR concentration, combining it with hydrophobic agents, and examining its long-term stability under varying environmental conditions to enhance its structural performance for sustainable building applications. Full article

The demand for innovative products from renewable sources has motivated research development to create new sustainable materials. Cassava starch (CS) has been widely used for bonding and composing different types of products. Particleboards produced from cocoa (Theobroma cacao), wood wastes, and CS adhesives can be an environmentally correct and economically profitable alternative to replacing traditional commercial panels. This study aimed to manufacture particleboards made with wood waste extracted from the stem of Theobroma cacao. The panels were bonded with different proportions of CS and urea–formaldehyde (UF) adhesives, and their physical–mechanical properties were determined. To manufacture the panels, cocoa wood wastes were mixed with the adhesive in ratios of 90:10, 70:30, and 50%:50% (CS/UF). Two control treatments were bonded with 100% of both adhesives. The resulting particleboards were employed as a reference to compare properties. The manufacturing process was carried out by cold pressing. Apparent density, water absorption, thickness swelling, and static bending strength were found for all panels. The data obtained were subjected to Levene’s homogeneity test, Shapiro–Wilk’s normality test, analysis of variance (ANOVA), and Tukey’s mean test. The results showed that the highest density value was 497.0 kg m⁻³, corresponding to the treatment composed of cocoa wood wastes bonded with 100% CS adhesive. The water absorption and thickness swelling results after a 24 h immersion showed that the panel formed using cocoa wood wastes and 100% UF had the lowest values, 22.1 and 11.2%. The highest bending strength value was 13.1 MPa for the experimental treatment composed of cocoa wood residue and 100% UF. However, this result did not differ statistically from the treatment (50–50). Therefore, cocoa wood waste combined with adhesive CS may be a sustainable alternative for producing particleboards. Full article

The continuous rise in global demand for wood products has led to an increase in prices and a surge in research into alternative resources. As a byproduct of the timber industry, bark has emerged as a promising supplement in particleboard (PB) production. However, its anatomical structure, the presence of extractives, and its inferior mechanical properties complicate the production process, which have not yet been fully overcome at a commercial scale. This study proposes a paradigm shift, advocating for separate and specialized bark constituent processing in a wet state. Three bark-based raw materials—namely, outer bark particles, bark fiber clumps, and bark fibers—were investigated under varying wood content scenarios. PBs with a target density of 0.7 g/cm³ and a thickness of 16 mm were produced using mixtures of these bark-based materials and wood particles in different ratios bonded with a urea–formaldehyde adhesive. The results demonstrated that these bark constituents exhibit distinct properties that can be optimized through tailored processing techniques. Compared to bark fibers, outer bark particles displayed about 40% lower water absorption and thickness swelling. However, bark fibers improved the internal bond by about 50% due to their favorable morphology compared to outer bark. These findings highlight the potential of bark as a valuable resource for particleboard production and pave the way for its efficient utilization through specialized processing strategies. Full article

This study explores the possibilities of utilisation of coniferous bark as a filler in wood–polymer composites (WPCs), its impact on properties such as the modulus of rupture (MOR), modulus of elasticity (MOE), thickness swelling (TS) and water absorption (WA) after 2 h and 24 h of immersion in water and the significance of this impact compared to other factors. Six variants of bark–polylactic acid (PLA) WPCs were manufactured, differentiated by their filler content and filler particle size. As a comparison, analogous composites filled with coniferous sawdust were also manufactured. Bark-filled composites were characterised by lower TS and WA after both 2 h and 24 h of immersion, as well as lower water contact angles and surface free energy. The bark filler decreased the composites’ MORs and MOEs, while greater differences were noticed for variants filled with small particles. The type of filler was the second most important factor contributing to variance in this study, with the filler content being the most important one. Full article