Volume 21 Issue 2

This study examined the mechanical, acoustic, and microstructural performance of epoxy composites reinforced with Snake Grass Fiber (SGF) and hybrid agro-waste fillers—Tamarind Seed Powder (TSP) and Wood Apple Shell Powder (WASP). Composites were fabricated by compression molding with a constant SGF content of 30 wt% and varying hybrid filler contents (5 to 15 wt%). Mechanical properties including tensile, flexural, compressive, impact strength, hardness, and water absorption were evaluated alongside sound absorption behavior. The incorporation of hybrid fillers significantly improved mechanical strength, surface hardness, and dimensional stability while reducing moisture uptake compared to SGF-only composites. The optimized hybrid composition exhibited superior properties, achieving tensile, flexural, compressive, and impact strengths of 58 MPa, 87 MPa, 70 MPa, and 8.98 J, respectively, with a hardness of 84 Shore D and reduced water absorption of 23%. Acoustic analysis revealed enhanced sound absorption, with a maximum absorption coefficient of 0.24 at an optimal filler-to-fiber ratio, attributed to synergy between fibrous reinforcement and porous fillers. SEM analysis confirmed uniform filler dispersion, improved interfacial bonding, and reduced voids, supporting the observed mechanical and acoustic enhancements. SGF-based hybrid agro-waste composites offer improved structural and sound-absorbing performance, making them suitable for sustainable automotive, construction, and acoustic insulation applications.

The combined effects of phosphorus fertilization (applied as triple superphosphate, TSP; Ca(H₂PO₄)₂·H₂O, 43 to 44% P₂O₅) and storage duration were studied relative to the physico-mechanical and biochemical properties of citron watermelon (Citrullus lanatus var. citroides). Five phosphorus application rates and three storage durations under ambient conditions were evaluated. Storage duration significantly impacted both quality and mechanical traits. Moisture content decreased progressively during storage, accompanied by increases in rind lightness (L*), yellowness (b*), and chroma (C*). After two months of storage, cutting force and deformation increased significantly, reflecting storage-induced modifications in tissue structure and viscoelastic behavior. Prolonged storage was also associated with a general decline in antioxidant-related biochemical parameters, suggesting degradation of bioactive compounds over time. Phosphorus fertilization did not significantly affect (P > 0.05) fruit weight, dimensional characteristics, color attributes, puncture resistance, or cutting-related mechanical parameters. In contrast, increasing phosphorus doses significantly enhanced total phenolic and flavonoid contents, total antioxidant activity, and chlorophyll contents, indicating the effect of phosphorus on secondary metabolism and antioxidant capacity. Overall, storage duration was the dominant factor influencing the structural and mechanical behavior of citron watermelon rind, whereas phosphorus fertilization primarily governed biochemical composition and antioxidant potential.

To minimize environmental impact, the green synthesis strategy prioritized using non-toxic substances, energy-efficient processes, and renewable resources. Ficus nitida fruit extract was used to produce Iron oxide nanoparticles (Fe₂O₃ and Fe₃O₄ NPs) and Iron oxide/cerium oxide nanoparticles (Fe₂O₃ and Fe₃O₄/CeO₂ NPs) for antimicrobial, and antioxidant applications. The effective synthesis of these NPs was confirmed by X-ray diffraction (XRD), FTIR, UV-visible, and transmission electron microscopic (TEM) analyses. The typical crystal diameters, as estimated by the Debye–Scherrer equation, were 3.65 nm (Fe₂O₃ and Fe₃O₄ NPs) and 10.14 nm (Fe₂O₃ and Fe₃O₄/CeO₂ NPs). TEM images verified that the prepared NPs were spherical, semispherical, and irregular in shape. The FTIR spectrum’s prominent peaks revealed the elements of Fe–Ce nanoparticles. Of all the materials examined, Fe₂O₃ and Fe₃O₄ /CeO₂ NPs synthesized using Ficus nitida fruit extract demonstrated promising in vitro antibacterial activity against MRSA (21.0 ± 0.58 mm inhibition zone) and E. coli (22.2 ± 0.15 mm), alongside antioxidant potential (81.76% free radical scavenging at 1000 µg/mL). These preliminary findings merit further investigation to assess toxicity, biocompatibility, and in vivo efficacy as potential antibacterial and antioxidant agents in advanced applications.

The effectiveness of Gum Arabic (GA) as a compatibilizer was evaluated in sodium lignosulfonate (LS)/polyvinyl alcohol (PVOH) composite film systems. This study aimed to improve the morphological integrity and mechanical stability of films, while achieving sustainability objectives. The goal was to obtain mechanically reinforced and morphologically homogeneous biodegradable films through GA-assisted phase stabilization. The structural, morphological, and mechanical properties, as well as the water interaction performance, of films were investigated. Fourier transform infrared analysis showed that the band intensity attributed to hydrogen bonding increased with the addition of GA, indicating enhanced molecular interactions. Scanning electron microscopy revealed that GA increased morphological defects such as microphase separation and aggregation, especially at low concentrations. While 25% GA helped fill the pores, it did not completely eliminate structural defects. Mechanical tests showed a decrease in tensile strength of up to 63% associated with such defects. Water sorption and dissolution tests showed that mass loss in aqueous media reached 75% due to the solubility of LS and GA. However, higher GA content moderately reduced this loss by minimizing defect sites. GA failed to act as a compatibilizer under tested formulation and processing parameters but contributed to the film’s surface homogeneity as a physical filler.

The mechanical performance of fiber-based materials depends not only on strength but also on elongation, which is particularly critical in converting and end-use applications. Wood-fiber-based materials, such as thermomechanical pulp (TMP) paper webs, are typically brittle and exhibit low breaking strain. However, both dry and wet strengths can be significantly improved through hot-pressing, especially in the presence of lignin. This study examines the influence of hot-pressing time on the complete stress–strain behavior of calendered TMP webs. Dry samples showed only minor, systematic changes in mechanical properties with increasing pressing time at 200 °C. In contrast, wet samples exhibited a pronounced increase in breaking strain for pressing times exceeding 1 s, accompanied by increased wet specific strength and tensile energy absorption. Wet stiffness also increased beyond what could be explained by densification alone, indicating enhanced inter-fiber bonding. To elucidate these effects, X-ray microtomography combined with image analysis was used to characterize microstructural features, including porosity, pore size, surface roughness, sheet thickness, and fiber wall density as functions of pressing time. The results demonstrate that extended hot-pressing promotes microstructural consolidation and bonding mechanisms that improve mechanical performance under both dry and wet conditions.

Softness of hygiene paper encompasses bulk softness and surface softness components. Bulk softness is determined by bulk flexibility, which is the inverse of tensile stiffness, while surface softness is determined by surface roughness and friction. Although refining is essential for modifying fiber properties to achieve the desired tissue web characteristics, it increases tissue web density after drying, resulting in diminished bulk softness. This study explored methods to minimize strength loss while enhancing bulk softness by using pulps refined separately. The objective was to develop optimal pulp mixtures that maintain bulk softness and high tensile strength with improved surface softness. The results highlight the potential to optimize pulp mixtures for enhanced bulk softness and tensile strength and suggest that customizing the pulp conditions can effectively manage properties such as surface roughness and friction. The heterogeneity of pulps originating from separate refining systems is crucial for achieving targeted bulk and surface softness components.

The influence of changing climatic conditions was studied relative to strength parameters—tensile strength, modulus of elasticity, and internal cohesion—of joints between hardened epoxy casting resin and solid wood. Samples were exposed to various climatic conditions, including ageing simulation under normal conditions (25 °C, 30% humidity), and extreme conditions (50 °C, 90% humidity). The study also examined the impact of incorporating oak wood dust (0.05% by weight) as a bio-based additive into the epoxy matrix. Chemical resistance of the cured resin—with and without the additive—was evaluated using a modified Buchholz indentation test following exposure to a toluene–naphtha–ethanol solvent mixture. Moisture content was assessed. Alternating climatic conditions significantly impacted the strength parameters, with extreme temperatures and humidity levels reducing joint integrity. Mechanical stress further exacerbated this deterioration, underscoring the importance of environmental considerations in applying resin-wood composites. Furthermore, the addition of oak wood dust improved the chemical resistance of the epoxy resin, suggesting enhanced durability and interfacial bonding. Visual inspection of post-failure specimens revealed a higher prevalence of cohesive wood failures in oak, indicating superior bonding compared to meranti. These findings offer insights for appropriate use of epoxy–wood joints in furniture applications conditions.

Compressed hybrid composite laminates with a thickness of 3 mm were fabricated using a skin–core configuration, employing jute and glass fabrics as reinforcements and epoxy as the matrix material. The impact performance and damage mechanisms of the jute/glass hybrid composites were compared against jute/epoxy composites with the same and variable thicknesses under varying low-velocity impact energies. The incorporation of glass fabric significantly improved the impact resistance of the thinner hybrid laminates. At a higher impact energy of 15 J, the hybrid composites exhibited a rebounding response, indicating superior energy absorption and damage tolerance. Laser shearography was utilized to examine the internal damage evolution, while computed tomography (CT) scanning was employed to quantitatively assess damage. An increase of up to 86% in the maximum impact load was observed from the hybrid composites with thickness of 3 mm when compared with the jute/epoxy laminates. CT scan analysis revealed completely perforated failure in the jute/epoxy composites with progressive crack propagation at different depths. The hybrid composites primarily exhibited localized sliding damage accompanied by surface denting, as observed through shearography. The findings confirmed that jute/glass hybrid composites offered an enhanced low-velocity impact resistance when compared with the pristine jute composites.

Challenges associated with the recyclability and end-of-life management of plastics are leading to a search for more environmentally friendly alternatives. The amount of conventional plastic that is recycled represents a tiny percentage of what is made. Most is sent to landfills or simply accumulates in the environment, which presents a challenge due to the generation of micro- and nanoplastics. Next-generation bioplastics have emerged as an option in recent years. Polyhydroxyalkanoates, polylactic acid, thermoplastic starch, lignocellulosic biocomposites, protein-based materials, seaweed, among others, can be regarded as promising alternatives to conventional plastics. These materials are innovative; some, such as polylactic acid and thermoplastic starch, are already established in the market, while others have recently gained ground in various sectors, including lignocellulosic biocomposites in the automotive industry and bioplastics based on marine algae for food packaging. However, this transition should not be limited to replacement. The study analyzes recent advances in next-generation bioplastics, including classification and potential applications. The study also explores key challenges and regulatory perspectives.

Physical (thickness swelling) and mechanical (modulus of rupture, modulus of elasticity, and internal bond) properties of the particleboard samples produced by mixing spruce (Picea orientalis) particles and oak (Quercus pontica) leaves at various ratios were investigated. Chemical composition of oak leaves and spruce wood (holocellulose, cellulose, lignin, ash content, alcohol-benzene solubility, 1% NaOH solubility, hot and cold-water solubility) were determined. Single-layer test panels were produced using urea-formaldehyde adhesive. Increasing the oak leaf content in the furnish negatively affected the mechanical strength properties, while improving the thickness swelling resistance. However, the particleboard samples produced with 10% oak leaves addition met the minimum mechanical requirements for general uses. Overall, it was found that oak leaves could be used as an alternative supplementary raw material source in the particleboard industry when blended with wood particles.