Search Results (90)

The objective of this study was to investigate the influence of the lignocellulose filler originating in wood and non-wood raw materials, alone or together with collagen hydrolysate, on the properties and biodegradation ability of natural rubber latex. The different hydrophobicity of the polymer matrix and natural filler makes it difficult to obtain a homogenous structure of the composite. However, the easy biodegradation of the natural filler is a sufficient reason to seek a compromise between its useful properties and the environmental safety of the material. The composites were filled with lignocellulose filler: pine, spruce, and birch wood flour or willow, raspberry, and mallow non-wood flour. Collagen hydrolysate was used as a substitute for lignocellulosic filler, together or alone. The mechanical properties of the composites, their hardness, and equilibrium swelling were studied. In order to determine the morphology and interactions between filler and latex, scanning electron microscopy together with infrared spectroscopy were engaged. The results revealed that after the incorporation of 4 phr of the filler, the increase in mechanical strength was observed even despite the lack of compatibility between the filler and polymer matrix. The lignocellulose filler is a promising agent because its biodegradability contributes to the overall environmental safety of the polymer material. Full article

Occupational exposure to commercial formic and acetic acids through dermal contact and inhalation during rubber sheet processing poses significant health risks to workers. Additionally, the use of these acids contributes to environmental pollution by contaminating water sources and soil. This study investigates the potential of three types of wood vinegar—derived from para-rubber wood, bamboo, and eucalyptus—obtained through biomass pyrolysis under anaerobic conditions, as sustainable alternatives to formic and acetic acids in the production of ribbed smoked sheets (RSSs). The organic constituents of each wood vinegar were characterized using gas chromatography and subsequently mixed with fresh natural latex to produce coagulated rubber sheets. The physical and chemical properties, equilibrium moisture content, and drying kinetics of the resulting sheets were then evaluated. The results indicated that wood vinegar derived from para-rubber wood contained a higher concentration of acetic acid compared to that obtained from bamboo and eucalyptus. As a result, rubber sheets coagulated with para-rubber wood and bamboo vinegars exhibited moisture sorption isotherms comparable to those of sheets coagulated with acetic acid, best described by the modified Henderson model. In contrast, sheets coagulated with eucalyptus-derived vinegar and formic acid followed the Oswin model. In terms of physical and chemical properties, extended drying times led to improved tensile strength in all samples. No statistically significant differences in tensile strength were observed between the experimental and reference samples. The concentration of acid was found to influence Mooney viscosity, the plasticity retention index (PRI), the thermogravimetric curve, and the overall coagulation process more significantly than the acid type. The drying kinetics of all five rubber sheet samples displayed similar trends, with the drying time decreasing in response to increases in drying temperature and airflow velocity. Full article

Heat treatment is a widely employed method for modifying solid wood and has also been extended to veneer-type woods. Owing to the thinness and ease of handling of veneers, the regulation of protective media in heat treatment has not been highly regarded by the industry and is scarcely reported in research. In light of this, in this paper, rubber wood (Hevea brasiliensis) veneer is taken as the research subject to investigate the influences of heat treatment with hot air (HTHA) and heat treatment with superheated steam (HTSS) at different temperatures on the chemical properties, longitudinal tensile strength, color values, hygroscopicity, thermal degradation performance and microstructure of the wood. The results show that heat treatment alters the chemical properties of wood. Both heat treatments reduce the content of hemicellulose and other components in the veneer, and the characteristic peak of lignin in HTSS is slightly enhanced. The crystallinity of the veneer slightly increases after heat treatment, and the increase in HTSS is greater than that in HTHA. Through scanning electron microscopy, it is observed that heat treatment can effectively remove starch granules in rubber wood veneer, with HTSS being superior to HTHA, and the removal effect increases with the rise in temperature. The longitudinal tensile strength of the veneer decreased by 0.69%, 3.87%, and 24.98% respectively at 135~155 °C HTHA, and by 3.25%, 7.00%, and 18.47% respectively at 135~155 °C HTSS. Both heat treatments reduced the lightness of the veneer and increased the chroma index. At 155 °C, the color difference value of the veneer treated by HTSS was smaller than that treated by HTHA. The effects of heat treatment on the moisture absorption performance of the veneer were different. The equilibrium moisture content of the veneer treated at 135 °C HTHA and 135~155 °C HTSS was lower than that of the untreated material, indicating an improvement in moisture absorption stability. The maximum moisture sorption hysteresis of untreated material is 3.39%. The maximum moisture sorption hysteresis of 135 °C HTHA is not much different from that of untreated material. The values of 145 °C and 155 °C HTHA increase by 8.85% and 9.14% respectively. The values of 135 °C, 145 °C, and 155 °C HTSS increase by 22.42%, 25.37%, and 19.47% respectively. The moisture absorption hysteresis of the veneer increases after heat treatment, and the effect of HTSS improvement is more significant. From the TG and DTG curves, it can be seen that the residual mass percentage of the veneer after heat treatment is higher than that of the untreated material. The residual mass percentage of HTHA at 135 °C, 145 °C, and 155 °C increased by 3.13%, 3.07%, and 2.06% respectively, and that of HTSS increased by 5.14%, 7.21%, and 6.08% respectively. Full article

This study aims to present a low-cost, non-destructive microwave sensor implementation to monitor the real-time moisture content of rubber wood in industrial dehydration processes. The proposed sensor is based on the free-space measurement technique with magnitudes S₁₁ and S₂₁ only. The novelties of this study consist of the natural frequency determination of rubber wood and the design of a sensor system using devices available on the market with reasonable cost performance. The natural frequency was determined using a simulation and was equal to 1.25 GHz. It specified the sensor system design and device selection. The designed system was initially verified by measuring the moisture content of rubber wood in the laboratory. The measured S₁₁ and S₂₁ voltages correlating with moisture content percentages were obtained and programmed. The system was then installed to monitor the moisture content of rubber wood in the dehydration process. The measured results deviated from those obtained from a standard method in the range of 7.67–15.38%. The error compensation was analyzed to improve the measured results that provided the deviated moisture content in the range of 3.58–5.21%. It can be inferred that the proposed sensor system has the capability to be implemented in industrial dehydration processes. Full article

Currently, workers in the ribbed smoked sheet (RSS) rubber production industry face increasing health risks, primarily due to their direct involvement in converting fresh latex into raw rubber sheets. This process involves the manual addition of appropriately diluted commercial formic acid and acetic acid to induce coagulation, resulting in a tofu-like consistency, which is subsequently processed into rubber sheets. Previous studies have indicated that the use of commercial formic and acetic acids poses significant health hazards to workers and contributes to environmental pollution. Therefore, this study explores the feasibility of replacing commercial formic and acetic acids with wood vinegar derived from para-rubber wood, bamboo, and eucalyptus in the RSS production process. Wood vinegar samples from the three biomass sources were analyzed for their organic compound compositions using gas chromatography and subsequently used as coagulants in the preparation of raw rubber sheets. The drying kinetics and antifungal properties of the resulting sheets were then evaluated. The results revealed that wood vinegar derived from para-rubber wood contained the highest concentration of acetic acid (41.34%), followed by bamboo (38.19%) and eucalyptus (31.25%). Rubber sheets coagulated with wood vinegar from para-rubber wood and bamboo exhibited drying kinetics comparable to those obtained using acetic acid, with the two-term exponential model providing the best fit. Conversely, rubber sheets coagulated with eucalyptus-derived wood vinegar, which had a relatively high concentration of phenolic derivatives (22.08%), followed drying behavior consistent with the Midilli et al. model, similar to sheets treated with formic acid. In terms of antifungal properties, five fungal genera—Aspergillus, Penicillium, Fusarium, Trichoderma, and Paecilomyces—were identified on the rubber sheets. Fungal growth was most pronounced in the control samples (untreated with wood vinegar), whereas samples treated with wood vinegar exhibited significantly reduced fungal colonization. These findings indicate that wood vinegar is effective in inhibiting fungal growth on the surface of rubber sheets and may serve as a safer and more environmentally friendly alternative to commercial acid coagulants. Full article

The aim of this study is to investigate the potential of wood composites as sustainable acoustic materials and to explore their integration with advanced manufacturing techniques for improved performance. Using a comprehensive review methodology, the paper analyzes recent innovations in wood composites, focusing on the combination with other sustainable materials such as expanded polystyrene (EPS) and natural fibers. The results show that wood composites can achieve sound absorption coefficients (α) of up to 0.9, with oak panels showing transmission losses of up to 11 dB. In addition, advanced designs, including biodegradable panels and lightweight honeycomb structures, significantly improve sound transmission loss, with an average sound transmission loss (TLeq) of up to 28.3 dB reported for composite panels made from waste tire rubber. In addition, the study highlights the environmental benefits achieved through the use of agricultural byproducts and industrial waste in the development of these materials, confirming the role of wood composites as a carbon-neutral alternative in the quest for green building solutions. This study provides valuable insights into the transformative potential of wood composites for sustainable acoustic applications. Full article

The bruising of fruits occurs at various stages, including picking, transportation, and sale. For fruits with large kernels that occupy a significant portion of their overall volume, considering the impact of the kernel is crucial in elucidating the mechanisms of bruising and controlling bruise formation. This study employs reverse engineering to develop a composite finite element model of loquat peel, flesh, and kernels. Bruise formation during collisions is analyzed from the perspectives of contact force, equivalent stress, energy, bruise volume, and bruise susceptibility, aiming to reveal the significant role of the fruit core in the bruise formation process. In this paper, we propose the use of 3D printing technology to accurately quantify bruise measurement for fruits with large kernels. The results showed that the maximum contact force, equivalent stress, and internal energy between loquat and steel/wood were essentially consistent, but all exceeded those observed when using rubber. Due to the blocking of stress transmission by the kernel, the susceptibility of loquats to bruising increases with height before decreasing. This study elucidates the mechanism of bruise formation in fruits with large kernels and provides methods and ideas for the research and precise measurement of complex fruit bruising characteristics. 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 transformation of the Cerrado biome into areas with different levels of activity and anthropic pressure negatively impacts biodiversity. This study evaluated the response of the dung beetle community to changes in land use systems: forests, rubber trees, pastures, and soybeans. Five areas were sampled in each system with a minimum distance of 2 km between them. Dung beetles were collected using pitfall traps, and both local (vegetation density, basal area of wooded vegetation, fractal dimension, litter height, electrical conductance (mV), water content in the soil (%), and soil resistance (kPa)) and landscape-related environmental variables (land use and overall composition and configuration of the landscape surrounding the sampling areas) were measured. In total, 2294 specimens were collected and distributed among 34 species and 18 genera. There was no significant difference in abundance between the systems, but differences in the number of species and biomass were observed between forest and soybean systems, as well as a separation of communities between the tree-covered (forest and rubber tree) and open (pasture and soybean) systems. Density and arboreal basal area were the main predictive variables for the diversity of the dung beetle community, reinforcing the importance of vegetation cover for maintaining diversity, whereas local and landscape-related variables influenced community composition. Full article

The growing interest in renewable resource-based materials has driven efforts to develop elastomeric biocomposites using biomass, phyto-ash, and biochar as fillers. These bio-additives, derived from beech wood through various processing methods, were incorporated into natural rubber (NR) at varying weight ratios. The primary objective of this study was to assess how the type and content of each bio-filler influence the structural, processing, and performance properties of the biocomposites. Mechanical properties, including tensile strength and hardness, were evaluated, while crosslink density of the vulcanizates was determined using equilibrium swelling in solvents. Additionally, the composites underwent thermogravimetric analysis (TGA) to determine the decomposition temperature of individual components within the polymer matrix. Bio-fillers influenced rheological and mechanical properties, with phyto-ash reducing viscosity and cross-linking density, and biochar and biomass increasing stiffness and maximum torque. Biochar extended curing time due to the absorption of curing agents, whereas phyto-ash accelerated vulcanization. Mechanical tests showed that all bio-filled composites were stiffer than the reference, with biochar and biomass (30 phr) exhibiting the highest hardness (45.8 °ShA and 49.1 °ShA, respectively) and cross-link density (2.68 × 10⁻⁵ mol/cm³ and 2.77 × 10⁻⁵ mol/cm³, respectively), contributing to improved tensile strength, in particular in the case of biochar, where the TS was 17.6 MPa. The study also examined the effects of thermal-oxidative aging on the samples, providing insights into the changes in the mechanical properties of the biocomposites under simulated aging conditions. Full article

The adverse effects of climate change, which are associated with the rise in greenhouse gases, impact all nations worldwide. In this context, tropical forests play a critical role in carbon sequestration. However, the significant anthropogenic pressure on these forests contributes to accelerated deforestation and a decrease in their capacity to regulate the climate. This study uses a comprehensive review of 176 published scientific articles and reports to assess the carbon sequestration capacity of rubber plantations, comparing their effectiveness with that of natural tropical forests. The findings are largely consistent and indicate that agricultural systems, such as rubber plantations, which were not traditionally associated with carbon sequestration, play a significant role in this area. Rubber plantations present a complementary alternative to the rapid deforestation of tropical forests, with the capacity to sequester substantial amounts of carbon. The range of carbon storage potential for rubber plantations, spanning from 30 to over 100 tons per hectare, rivals that of natural tropical forests, which can store over 300 tons per hectare. Furthermore, rubber plantations are notable for their indirect carbon sequestration potential. By providing a sustainable source of latex and wood, and thus income, they can reduce the pressure on natural tropical forests. However, challenges remain, particularly concerning sustainable management and the integration of rubber plantations into sustainable tropical forest management strategies. This analysis focuses on the opportunities and challenges of rubber plantations as an offset solution for carbon sequestration. It highlights the prospects for effectively integrating these plantations into sustainable tropical forest management policies. Full article

The vibration response of a component, particularly the frequency response of the component, can be used in the determination of the loss factor damping, η, due to energy dissipation and the elastic modulus (E). The ASTM E756-04 standard provides the methodology and the guidance for the determination of the loss factor damping and elastic modulus experimentally. This standard specifically calls for the use of a beam with a rectangular cross-section. Also, the theoretical formulation developed there is based on such a beam cross-section. Here, in this paper, the theoretical formulation and numerical simulation for determining the loss factor damping and elastic modulus are a derivation of the methodology used in the ASTM standard and other R&D work, but for a circular plate configuration. The delta change derivation, both theoretically and numerically, is proven to be accurate and validated here. This method is useful in the characterization of materials that have applications in structural vibration, aerospace subcomponents, micro and mini sensory devices, medical devices, and many other areas. Similar to the ASTM standard, the materials could include metals, ceramics, rubbers, plastics, reinforced epoxy matrices, composites, and woods. This paper mainly formulates the technique via numerical and computational methods. It is the intention of the author to also, as a future research agenda, experimentally produce data that can be correlated with this theoretical and numerical methodology. Full article

A demand to replace an easily combustible wood with wood–plastic–rubber composite with better thermal performance than wood is at its peak globally. Wood-based composite materials in the form of wood–polymer composite (WPC) have emerged as new materials that can replace wood to produce wood products for various use. The use of recycled polymers as biodegradable polymer blended with fiber particles, waste tire powder, and other substances to manufacture new products known as wood–rubber–plastics composite (WRPC) for building construction and other different applications, has piqued the interest of numerous researchers. High flammability and weak combustibility parameters are a setback for many wood-based composites because of the flammability of these composites. Fabricated WRPC based on non-toxic fire retardants and other additives used to modify the flame-resistant quality of these composites, the fabrication techniques, and mechanical characteristics are herein reviewed. It is hoped that better composite in the form of WRPC can be used as building materials for informal and formal dwellings. Full article

This study is based on a 10-day survey carried out at seven beaches in March 2023 in El Puerto de Santa María municipality (SW Spain). An amount of 5592 items were collected, with a combined weight of 26 kg. Fresh litter, which refers to litter transported to the shore by marine/coastal processes, accounted for 4634 items weighing 23 kg. The remaining 958 items, weighing 3 kg, were identified as litter deposited by beach visitors. The average total litter recorded during the sampling was 0.40 ± 0.07 items m⁻¹ with a density of 1.85 ± 0.69 g m⁻¹. Litter materials were relatively consistent regardless of whether they were stranded by marine processes or discharged by beachgoers. Plastic dominates fresh and deposited litter followed by metal and glass, with minimal contributions of chemicals, organic matter, clothing, rubber, wood, and paper. They were identified 115 items’ categories from the 184 listed in the EU Joint List: 107 for fresh and 75 for deposited litter. Food consumption-related items made up a significant portion of the total debris followed by personal hygiene and care-related and smoking-related litter. The obtained information is very useful to propose sound management actions that have to be especially devoted to raise beach users’ responsibility. Last, in order to have a year-round view of litter characteristics and behavior, further investigations should be carried out during winter, when the number of visitors is very low and waves’ energy is high, and summer, when opposite conditions are recorded. Full article

Plastics play an indispensable role in modern society, yet their long-term durability poses severe environmental challenges, with mismanaged waste polluting ecosystems worldwide. The transition to a circular economy emphasizes the importance of recycling and resource recovery to mitigate these impacts. While conventional disposal methods like mechanical and chemical recycling or incineration face limitations such as quality degradation, high costs, or pollutant emissions, value-added approaches present an innovative solution. This review explores the potential of integrating recycled plastic waste into composite materials to enhance performance and sustainability. Focusing on diverse strategies, the paper highlights the use of recycled plastics in combination with fibers, wood, metal, concrete, glass, rubber, textiles, and foam. These composites demonstrate superior mechanical, thermal, and chemical properties, enabling applications across industries like construction, automotive, aerospace, and furniture. Furthermore, various roles of plastic waste—such as filler, reinforcement, matrix, or additive—are analyzed to showcase advancements in material innovation. By presenting methodologies and outcomes from recent research, this paper underscores the potential of recycled plastics in creating high-performance materials, supporting sustainable development and circular economic goals. Full article