Research Articles

The mechanical and free vibration behaviors of unsaturated polyester matrix composites reinforced with 10-, 50-, and 150-mm-long palmyra palm leaf stalk fibers were examined. The fibers were alkali-treated before being used as reinforcement, which improved fiber-matrix interfacial strength, while reducing their hydrophilic character. The hand layup process followed by compression molding technique were used to produce the composites. Experiments were conducted to determine the tensile, flexural, impact, and vibration characteristics following the required ASTM standards. The results demonstrated that the most effective adhesion with the matrix was achieved with 50-mm-long fibers. To identify the properties of free vibration, a fast Fourier transform analyzer was used. Longer fibers offered slightly higher natural frequencies in the composites. To understand the mechanism of fracture, specimens that had been subjected to tensile testing were analyzed using scanning electron microscopy. Developing engineering applications with effective vibration-damping capabilities for a sound absorption potential compared to other lignocellulosic fiber composites may be achieved using palmyra palm leaf stalk fibers-reinforced composites.

The benefits of hydrothermal carbonization (HTC) for carbon sequestration, energy, and soil remediation are widely recognized. Up to the present, there has been much research on hydrochar from terrestrial biomass residues, but there is little research on hydrochar based on aquatic plants. In this study, the physical and chemical properties of water hyacinth (representative of aquatic plants) and corn stalk (representative of terrestrial plants) were systematically analyzed under the condition of single hydrothermal carbonization. The results showed that water hyacinth-based hydrochar (WHHC) had well-developed pores, rich functional groups, and high nitrogen content. Among them, the nitrogen content of WHHC was 3.83%, which was more than three times the nitrogen content of corn straw-based hydrothermal carbon (CSHC) (1.11%), and the number of micropores, mesoporous pores, and macropores were also higher than that of CSHC. These differences were attributed to the contrasting growing environments and main components of water hyacinth and corn stalk. These differences revealed their potential application directions: WHHC can be used as an adsorbent and soil amendment; CSHC is more suitable as a supplementary energy source because of its higher carbon content and stability.

Robinia wood has a high technical and economic potential due to its future availability, its mechanical properties, and its durability. This also applies to its use in structural timber construction. Such applications require the manufacture of bonded construction products from this type of wood in order to compensate for dimensional shortcomings. In an application-oriented research project, tests were carried out for manufacturing technologies and resulting properties of glued laminated timber made from the hardwood species Robinia for structural purposes. Based on adapted visual grading rules, the strength and stiffness profiles of Robinia laminations were evaluated. The influence of different adhesive types and of production parameters on the strength and durability properties of glued finger joints and glulam bond-lines were characterised. By means of a simulation model based on X-FEM methods in combination with Monte Carlo simulations, the property potential of glued Robinia laminated timber was calculated. The model was calibrated by means of input parameters from the empirical lamination and finger joint test data and verified by a small series of full-scale glulam tests. The investigations showed the great potential of Robinia glulam, especially in highly loaded and heavily weathered applications.

Effects of adding wollastonite (W, at 5% and 10%) and palm leaf residues(at 10%), based on the dry weight of wood fibers, were evaluated relative to selected properties of medium-density fiberboards (MDF), bonded with two adhesive systems, i.e., urea-formaldehyde (UF, at 10%) and isocyanate (IC, at 5%) resins. The results indicated a general improvement in screw withdrawal resistance in the UF-bonded panels due to the addition of wollastonite. This enhancement is attributed to the reinforcing effect of wollastonite. In the IC-bonded panels, the addition of wollastonite had an improving effect when W-content was 5%. The addition of defibrated palm leaves generally decreased the screw withdrawal resistance of the MDF panels due to the soft nature of the palm fibers. The fire properties of the IC-bonded panels tended to be more favorable or at least comparable to those of the UF-bonded panels, which was attributed to the formation of bubbles in the cured resin. The addition of wollastonite generally improved fire properties in both resins. It was concluded that wollastonite and defibrated palm leaves can be recommended for MDF production when the contents of wollastonite and palm leaves do not exceed 5% and 10%, respectively.

The main objective of this study was to manufacture and test environmentally friendly composite materials using biomass residues as reinforcement: pine needles and recovered paper. A mixed matrix was also used, with natural dammar resin as the predominant component, in order to favor the eco-friendly nature of the resulting material. The manufacturing process employed was the lay-up hand technique. Another objective was to investigate how dammar resin influences the mechanical properties as its mass percentage increases in the mixed resin composition. To investigate the influence of dammar resin on the mechanical properties of the composites, additional materials were fabricated for comparison, using the same reinforcements but with two types of synthetic matrices: epoxy and acrylic. The samples were tested for tensile strength, compression, bending, Shore D hardness, and vibrations.The results indicated that as the percentage of dammar in the matrix increased, a decrease in the strength and rigidity of the material occurred, accompanied by an increase in elasticity and ductility. Water absorption tests showed that the saturation process occurred much faster, as pine needles tend not to absorb a significant amount of water due to the presence of lignin, wax, resins, and pectin, which act as a natural water-repellent barrier.

Thermoplastic starch (TPS) was evaluated as a filler in a poly(butylene adipate-co-terephthalate) (PBAT) matrix. The effect of different levels of TPS (0%, 10%, 30%, 50%) on the composite was studied. The TPS/PBAT composites were prepared by melt blending modification and high temperature moulding. The mechanical properties, hygroscopicity, water absorption, thermal stability, and micromorphology of the PBAT-based composites were tested. The results showed that the tensile strength of TPS/PBAT composites decreased from 13.7 to 3.83 MPa when the TPS content was increased from 0 wt% to 50 wt%; the flexural and tensile strengths of the composites with the addition of 10 wt% TPS were increased by 14.9% and 16.3%, respectively, compared to those of pure PBAT. The water absorption, moisture absorption balance and contact angle of the composites were improved and the contact angle of the 30 wt% TPS/PBAT composites reached 108 deg. The addition of TPS reduced the coefficient of linear expansion of the composites, which showed better thermal stability. The results are important for the development of new biodegradable composites.

The adsorption of phenol and Pb²⁺ from aqueous solutions was achieved using calcined animal waste (cow dung) as a low-cost adsorbent. Fourier transform infrared analysis confirmed the involvement of hydroxyl, carbonate, and possibly silicate functional groups in the adsorption process. Scanning electron microscope images revealed the presence of distinct rod-like fibers on the adsorbent surface. Adsorption kinetics revealed an increase in pollutant uptake over time, with the effect being more pronounced at a higher initial concentration of 280 mg/L. The optimal pH for maximum adsorption was identified as 6.5 for phenol and 4.5 for lead. Langmuir isotherm analysis indicated a higher adsorption affinity for lead, with a maximum adsorption capacity of 101 mg/g, compared to 89.3 mg/g for phenol. Conversely, the Freundlich isotherm model demonstrated a better fit for phenol adsorption. Thermodynamic evaluations showed negative ΔG° values, confirming the spontaneous nature of the sorption process for both pollutants. The enthalpy change (ΔH°) values of 11.6 kJ/mol for phenol and 21.7 kJ/mol for lead validated the endothermic nature of the adsorption. These results underscore the effectiveness of calcined animal waste as a sustainable and efficient adsorbent for eliminating phenol and lead from wastewater.

Biomass ash from agricultural residues, which is typically discarded and causing waste and pollution, was evaluated in tea-bag form as a natural food preservative in this study, addressing research gaps on its effects and safety. In vitro tests on six biomass ash extracts demonstrated significant antibacterial activity. Specifically, the golden leaf fine branch camellia extract exhibited the highest efficacy against Staphylococcus aureus and Alternaria brassicicola, with an inhibition zone of 21 mm and an antibacterial efficiency of 70.2%. Fruit storage tests confirmed its preservative ability. Golden leaf fine branch camellia twig and leaves ash exhibited the most effective weight loss reduction for potatoes, corn stalks ash was found to be optimal for green peppers, rice straw ash offered the most effective preservation for sugar oranges, and soybean straw ash yielded favorable outcomes for mangoes. Safety evaluations revealed no genotoxicity, with lead content below the 0.2 mg/kg safety threshold and the micronucleus tests within safe limits. Elemental analysis detected high potassium content (103.127 g/kg), while SEM and FTIR revealed a porous structure and functional groups that may contribute to its antibacterial and preservative properties. In conclusion, biomass ash has strong antimicrobial and preservative properties, is non-genotoxic, and shows great potential as a natural food preservative, providing a new avenue for biomass ash resource utilization.

Within the context of educational innovation, diversified teaching models impose higher requirements on classroom furniture adaptability. However, conflicting multi-stakeholder demands and configuration imbalances constrain the upgrading of educational spaces. To address this, this study focuses on the “demand-configuration” contradiction and constructs a composite evaluation model integrating the “game theory combined weighting method – fuzzy comprehensive evaluation method – quadrant diagram model”. Through improved Analytic Hierarchy Process (AHP) and entropy method game weighting, this approach can balance multi-party weight conflicts, quantify user satisfaction based on fuzzy evaluation, and identify “high demand-low adaptation” core indicators using the quadrant diagram. Taking classroom furniture in M Middle School as a practical case, results demonstrate that the quadrant diagram model accurately identified six core indicators based on comprehensive weights and satisfaction levels, aligning with current key optimization directions for classroom furniture. This validates the model’s feasibility and accuracy in resolving contradictions between multi-dimensional demands and actual configurations. The proposed evaluation system provides a framework of “demand deconstruction-efficiency evaluation-design guidance” for educational furniture design, which is applicable to quasi-public product design evaluation fields involving multiple stakeholders such as public medical products, thereby enhancing the matching efficiency between product resource allocation and diverse demands.

The extent of spoilage of fruits and vegetables increases post harvest, and fungi is one of the greatest causes. The effect of sodium silicate on Aspergillus flavus and its cell wall degrading enzymes, namely polygalacturonic acid transeliminase (PGTE), pectin methyltranseliminase (PMTE), and pectin lyase (PL), was investigated via molecular docking. At the 4^th day, 100 mM of sodium silicate completely inhibited A. flavus, while it reflected 79.70, 61.16, 56.82, and 37.23% inhibition at 6, 8,10, and 12 days, respectively. The PGTE (369.33 ± 2.08 U/mL) showed maximum activity at 8^th day in the medium without sodium silicate, also at 20 to 80 mM sodium silicate, their maximum activity was recorded at the 8^th day, while it reached to maximum at 10^th day in the medium with 100 mM sodium silicate. The PMTE recorded highest activity at the 6^th day (414.00 ± 1.73 U/mL) without sodium silicate, at 8^th day when sodium silicate ranged from 20 to 80 mM, and at 10^th day (97.67 ± 1.25 U/mL) with 100 mM sodium silicate. Day 8 was optimum for PL activity. Sodium silicate demonstrates potent interaction with the active sites of the studied proteins, suggesting its potential as a molecular inhibitor of studied enzymes.