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In the manufacturing of composite materials, achieving high precision in drilling processes is crucial to ensure product quality and performance. This study investigates the influence of drilling parameters on key performance metrics delamination, circularity, and cylindricity using the Taguchi method. An L25 orthogonal array was employed to systematically explore the effects of spindle speed, feed, and drill type on the quality of drilled holes. The analysis of variance (ANOVA) revealed that feed significantly influences the outcomes across all drill materials, with cutting speed playing a secondary role. The study further applied desirability function analysis (DFA) to optimize these multi-responses, identifying the optimal parameter settings for each drill type. The results highlight the critical role of feed in minimizing delamination, circularity, and cylindricity with the optimal settings offering significant improvements in drilling performance. [ABSTRACT FROM AUTHOR]

This research paper focuses on the design and fabrication of natural cotton epoxy composites. By combining natural cotton fibers with epoxy resin, the study aims to develop composite materials with desirable mechanical properties. To evaluate their performance, the composites were subjected to three-point bending tests, which revealed an average flexural strength of 50 MPa and a flexural modulus of 3.8 GPa, highlighting the material’s capacity to bear bending loads. The bending tests provided insights into the composite’s response to flexural loads, including its strength, stiffness, and failure mechanisms. Post-test analysis using an optical microscope revealed that the primary failure modes included delamination and fiber breakage. Delamination, characterized by the separation of layers within the composite, and fiber breakage, caused by the fibers’ inability to withstand stress exceeding their tensile strength of approximately 300 MPa, led to crack propagation through the material. These findings indicate that the composite's failure was primarily driven by these mechanisms. This study provides valuable insights into improving the composite's design and enhancing its mechanical properties, contributing to the broader understanding of natural fiber-reinforced composites and their behavior under mechanical stress.Article Highlights: The study focuses on developing natural cotton epoxy composites and evaluates their mechanical properties through three-point bending tests. Optical microscopy reveals that the primary failure modes in these composites are delamination and fiber breakage. The bending tests provide valuable data on the composite's flexural strength, stiffness, and response to stress. [ABSTRACT FROM AUTHOR]

Natural fiber composites have gained increasing attention due to sustainability considerations. One often neglected aspect is the potential for the mechanical recycling of such materials. In this work, we compounded injection-molded polypropylene (PP) and polylactic acid (PLA) short cellulose fiber composites with fiber shares up to 40 percent by weight. Both matrix materials were reinforced by the addition of the fibers. We investigated a trifold full recycling process, where we subjected the materials produced in the first place to compounding, injection molding, testing, and shredding, and then repeated the process. Although the materials' properties assigned to degradation were found to decrease with progressive recycling, attractive mechanical properties could be preserved even after the third reprocessing cycle. [ABSTRACT FROM AUTHOR]

In the present work, sugarcane bagasse (SCB) fibers were used as natural reinforcement to low-density polyethylene matrix to benefit from and get rid of unexploited Egyptian natural resources in bio-composites applications. The samples were prepared by injection molding processes using various fiber content (10 wt%, 20 wt% and 30 wt%). The fibers were treated chemically with 3% sodium hydroxide (NaOH) to improve compatibility and adhesion with the matrix. Maleic anhydride was added as a coupling agent to improve interfacial adhesion. The mechanical properties such as tensile and flexural tests were performed according to ASTM standards. The chemical resistance of fabricated composites was also examined. The results indicated that the alkali treatment modified the fiber surface and increased the interaction between the fiber and the matrix. They also showed that adding the coupling agent improved the interfacial adhesion between the fibers and the polyethylene. Additionally, the results showed that the maximum improvement of the fabricated composites with various fiber loadings was found at the 30 wt% treated coupled composites with tensile strength (17.5 MPa) and flexural (19.6 MPa). This reflected an enhancement in tensile strength by 41% and flexural strength by 72% at 30 wt% fiber compared to the neat polymer, respectively. The results also indicated that chemical resistance decreased with increasing fiber content. But it was found that the chemical resistance for aqueous solution 3.5 wt% Nacl was enhanced when the coupling agent was used. The greatest improvement in the resistance was observed for coupled treated SCB composite, followed by coupled untreated SCB composites. This reflected that the addition of maleic anhydride (MAPE) along with the composites improved the chemical resistance of the composites for aqueous solution 3.5 wt% Nacl. [ABSTRACT FROM AUTHOR]

The escalating global population and subsequent demand for agricultural products have led to a surge in agricultural waste generation, posing significant disposal challenges. Conventional disposal methods such as burning and dumping not only harm the environment but also jeopardize human health and safety. Recognizing the urgent need for sustainable waste management, researchers have increasingly focused on repurposing agricultural plant waste as a valuable resource. This paper presents a comprehensive review of the potential of agricultural plant waste in wealth creation and sustainable development. It highlights the detrimental impacts of current disposal methods and emphasizes the necessity for alternative approaches. By analyzing the physical, mechanical, and chemical properties of plant fibers, particularly cellulose, hemicellulose, and lignin, this review underscores their suitability for diverse applications. Moreover, it explores the emerging trend of utilizing pineapple leaf fiber, a sustainable and lightweight material, in structural applications, such as UAV construction. With its exceptional mechanical properties and biodegradability, pineapple leaf fiber holds promise as a viable alternative to traditional materials, contributing to a more sustainable future. In conclusion, this review advocates for a paradigm shift towards embracing agricultural plant waste as a valuable asset for economic prosperity and environmental sustainability. It underscores the importance of continued research and technological advancements to unlock the full potential of agricultural waste in fostering a circular economy and driving sustainable development globally. [ABSTRACT FROM AUTHOR]

Wood–Textile Composites (WTCs) are a new type of composite material based on willow wood strips and polypropylene that combines the properties of classic natural-fiber-reinforced polymers with an innovative textile wood design. While the basic quasi-static properties have already been investigated and described, there is a lack of knowledge about the behavior of the material under dynamic-cyclic and dynamic-impact loading as well as in relation to basic wood construction parameters. The present study is intended to contribute to the later use of the developed material, e.g., in architecture. For this purpose, fatigue tests, dart drop tests (impact and penetration), impact bending tests, and embedment tests were carried out. It was shown that embedding wood fabrics in a thermoplastic matrix leads to a significant increase in resistance to impact loads compared to the neat basic materials. It was also shown that the ratio of the failure stress in the fatigue test to the tensile strength of the WTC corresponds to that of other fiber-reinforced thermoplastics at around 70%. The embedment tests showed that WTC has good values compared to neat wood. [ABSTRACT FROM AUTHOR]

Abstract This research paper focuses on the design and fabrication of natural cotton epoxy composites. By combining natural cotton fibers with epoxy resin, the study aims to develop composite materials with desirable mechanical properties. To evaluate their performance, the composites were subjected to three-point bending tests, which revealed an average flexural strength of 50 MPa and a flexural modulus of 3.8 GPa, highlighting the material’s capacity to bear bending loads. The bending tests provided insights into the composite’s response to flexural loads, including its strength, stiffness, and failure mechanisms. Post-test analysis using an optical microscope revealed that the primary failure modes included delamination and fiber breakage. Delamination, characterized by the separation of layers within the composite, and fiber breakage, caused by the fibers’ inability to withstand stress exceeding their tensile strength of approximately 300 MPa, led to crack propagation through the material. These findings indicate that the composite's failure was primarily driven by these mechanisms. This study provides valuable insights into improving the composite's design and enhancing its mechanical properties, contributing to the broader understanding of natural fiber-reinforced composites and their behavior under mechanical stress.

Natural fiber composites have gained increasing attention due to sustainability considerations. One often neglected aspect is the potential for the mechanical recycling of such materials. In this work, we compounded injection-molded polypropylene (PP) and polylactic acid (PLA) short cellulose fiber composites with fiber shares up to 40 percent by weight. Both matrix materials were reinforced by the addition of the fibers. We investigated a trifold full recycling process, where we subjected the materials produced in the first place to compounding, injection molding, testing, and shredding, and then repeated the process. Although the materials’ properties assigned to degradation were found to decrease with progressive recycling, attractive mechanical properties could be preserved even after the third reprocessing cycle.

The ongoing research focuses on exploring the potential of Careya arborea (CA) fiber, banana fiber (BF), and epoxy composites as sustainable alternatives to petroleum-based products and synthetic fibers. The aim is to enhance the interfacial bonding and overall performance of these composites while reducing reliance on traditional materials. The study investigates the adhesion between CA fiber, BF (both chemically treated), and epoxy with polylactic acid (PLA) coating. Specifically, it examined how the PLA coating affects the mechanical properties, including tensile strength, flexural strength, impact resistance, and water absorption behavior, of the fabricated composites. Mechanical characterizations of the composite specimens are conducted following ASTM standards. The PLA-coated and NaOH-treated specimens significantly improved their tensile strength (20.56%) and flexural strength (16.7%), and significantly reduced their water absorption capacity (by 47.6%) compared to the untreated ones. These findings highlight the promise of using treated natural fibers and PLA coatings to create more sustainable and high-performance composite materials.

The increasing demand for environmental and sustainable materials has motivated efforts to fabricate biocomposites as alternatives to conventional synthetic fiber composites. However, biocomposite materials have some drawbacks such as poor mechanical resistance, fiber/matrix incompatibility, low thermal resistance and high moisture absorption. Extensive research has been conducted to address these challenges, in terms of the sustainable production, serviceability, reliability and properties of these novel biocomposites. Silk fibers have excellent biocompatibility and biodegradability along with moderate mechanical properties, while flax fibers have a high specific strength and modulus. The combination of the silk fiber with moderate modulus and stiffness with flax fibers with high specific strength and modulus allows the modulation of the properties of silk using the intra- and inter-hybridization of both fibers. In this study, silk and flax fibers are combined in different arrangements, totaling eight different composites; the quasi-static mechanical properties and dynamic mechanical thermal analysis are discussed, focusing on the structure versus relationship properties, with the aim of corroborating the freely available data from literature. The main findings indicated that the synergic effect of the flax fiber and silk fiber leads to a tailormade composite with a low cost and high performance.

Highlights The demand for natural fiber‐reinforced polymer composites is increasing in the automotive industry, and Mexican blue‐gave fiber (AF) is getting attention from automakers. Quantitative characterization of the tensile behavior of AF allows for a better ascertain of fiber performance. This work developed a model to study the elastoplastic behavior of AF prior and after its incorporation within a thermoplastic matrix. Finite element predictions showed excellent agreement with both theoretical and experimental values from literature. It was revealed that the increase in the fiber aspect ratio hastens the interaction between nearby defects within the fiber with earlier coalescence of voids, and ultimately fosters the loss of both fiber ductility and load carrying capacity. Moreover, the preponderant character of the damage in AF is controlled by nucleation and growth of voids. On the other hand, AF reinforced thermoplastic composites exhibit a microfailure based essentially on the matrix failure, and the composites become more damage tolerant with the increase in fiber aspect ratio. Stiffer AF leads to a more uniform interfacial shear stress distribution, with higher stiffness of the composite. Therefore, the effectiveness of AF to reinforce polymeric matrixes depends strongly on the elastic mismatch of the coupled materials. Local stress state in AF is correlated to macroscopic stress. AF may be recognized as a von Mises material. Ductile fracture in AF is controlled by nucleation and growth of voids. Increasing the fiber aspect ratio leads to more damage tolerant composites. Stiffer AF led to a more uniform interfacial shear stress distribution. [ABSTRACT FROM AUTHOR]

Nowadays, fiber composites are among the most important construction materials in lightweight design. Increasingly, attempts are being made to replace fossil raw materials with bio-based materials in order to improve their recyclability and reduce greenhouse gas emissions. While processes suitable for industrial use already exist for the production of biopolymers as matrix materials, there is still a considerable need for research in the production of bio-based reinforcing fibers. For hemp bast strips (HBS), promising utilization options arise due to very good mechanical properties. However, current processes for extracting such raw materials from bast fiber plants result in damage to the fiber structure because they use biochemical decomposition processes and/or squeeze and crush large disordered amounts of stalk along their entire length. This strongly reduces the application potential of the raw materials. A newly developed principle extracts the HBS with minimal impact by dividing single hemp stalks only at one end and then isolating them from the wood core by pulling on the resulting wood fragments. In this manner, the fiber structure and the good mechanical properties are largely retained and the HBS obtained can be stored in parallel alignment for further processing with little effort. [ABSTRACT FROM AUTHOR]

The increasing demand for environmental and sustainable materials has motivated efforts to fabricate biocomposites as alternatives to conventional synthetic fiber composites. However, biocomposite materials have some drawbacks such as poor mechanical resistance, fiber/matrix incompatibility, low thermal resistance and high moisture absorption. Extensive research has been conducted to address these challenges, in terms of the sustainable production, serviceability, reliability and properties of these novel biocomposites. Silk fibers have excellent biocompatibility and biodegradability along with moderate mechanical properties, while flax fibers have a high specific strength and modulus. The combination of the silk fiber with moderate modulus and stiffness with flax fibers with high specific strength and modulus allows the modulation of the properties of silk using the intra- and inter-hybridization of both fibers. In this study, silk and flax fibers are combined in different arrangements, totaling eight different composites; the quasi-static mechanical properties and dynamic mechanical thermal analysis are discussed, focusing on the structure versus relationship properties, with the aim of corroborating the freely available data from literature. The main findings indicated that the synergic effect of the flax fiber and silk fiber leads to a tailormade composite with a low cost and high performance. [ABSTRACT FROM AUTHOR]

The use of lightweight natural fiber functional composites in the manufacturing of ballistic protective materials has garnered significant attention in recent years. This is due to their superior mechanical properties, cost-effectiveness, and environmental sustainability. Ballistic panels are constructed using multiple layers of diverse composites, which collectively exhibit excellent mechanical properties. These properties enable them to withstand strong impacts enhancing their capability for different applications in defense, military, and aerospace components. The primary focus of this review is to examine the different influential factors that govern the development of novel polymeric materials for current ballistic applications. It also explores various research approaches, such as experimental, analytical, numerical modeling, and empirical techniques. The review highlights both internal factors, such as material composition, and external factors, such as projectile parameters (e.g., nose angles, projectile shape, and projectile size). These factors are crucial for optimizing the robust ballistic performance of natural fiber-based polymer composites. In addition, various valuable insights to develop more effective and sustainable ballistic protective materials for applications in bulletproof helmets, defense, aerospace, and military sectors have also been elaborated. Consequently, the article presents a comprehensive review of the impact of utilizing various natural fibers as alternative materials to Kevlar for armor structures, offering a state-of-the-art perspective and challenges faced in full-scale implementation. [ABSTRACT FROM AUTHOR]

The incorporation of natural fibers into fiber-reinforced polymer composites (FRPC) has the potential to bolster their sustainability. A critical attribute of FRPC is the fiber volume content (FVC), a parameter that profoundly influences their thermo-mechanical characteristics. However, the determination of FVC in natural fiber composites (NFC) through manual analysis of light microscopy images is a labor-intensive process. In this work, it is demonstrated that the pixels from light microscopy images of NFC can be utilized to predict FVC using machine learning (ML) models. In this proof-of-concept investigation, it is shown that convolutional neural network-based models predict FVC with an accuracy required in polymer engineering applications, with a mean average error of 2.72% and an R2 coefficient of 0.85. Finally, it is shown that much simpler ML models, non-specialized in image recognition, besides being much easier and more efficient to optimize and train, can also deliver good accuracies required for FVC characterization, which not only contributes to the sustainability, but also facilitates the access of such models by researchers in regions with little computational resources. This study marks a substantial advancement in the area of automated characterization of NFC, and democratization of knowledge, offering a promising avenue for the enhancement of sustainable materials.

Natural fibers are a sustainable alternative to synthetic fibers due to their high weight‐specific Young's moduli and strengths. However, the mechanical properties of natural fibers are very sensitive to their moisture content. Therefore, chemical treatments are often applied to natural fibers to lower their water absorption and enhance fiber‐matrix interaction. The aim is to study the effects of fiber modifications with sodium hydroxide, silane, and siloxane on the water uptake and tensile properties of flax fiber composites produced via prepreg technology. In addition, the effect of moisture on the composites' tensile properties was investigated by conditioning one part of the tensile specimens according to DIN EN 2823 (at 70°C and 85% relative humidity). The NaOH treatment was the only modification that had positive effects on the Young's modulus and tensile strength in the unconditioned and conditioned state. The increase of the tensile modulus and strength are most likely due to changes in flax fiber composition, crystallinity of the cellulose and the rougher fiber surface of NaOH modified fibers. This shows that chemical treatment of natural fibers may improve the performance level of natural fiber composites and prevent a loss in their mechanical properties in humid environments. Highlights: Flax fiber modifications with sodium hydroxide, silane, and siloxane.Flax fiber composite production via prepreg technology.Water uptake after conditioning at 70°C and 85% relative humidity.Tensile tests before and after conditioning.SEM images of modified flax fibers. [ABSTRACT FROM AUTHOR]

Alkali pretreatment of fibers is an efficient technique to enhance fiber/matrix bonding in natural fiber composites. This study investigates if the addition of sodium dodecyl sulfate (SDS) surfactant increases the efficacy of alkali treatment of hemp fibers. SDS concentrations ranging between 2 and 10% wt/wt were used with a constant (10% wt/wt) NaOH concentration. Fiber surfaces were observed with scanning electron microscopy (SEM). Fiber surfaces were cleaner when SDS was used compared with alkali treatment with no SDS added indicating the elimination of substances such as lignin, waxes, hemicelluloses, and pectin. Fourier‐transform infrared spectroscopy and TGA studies also confirmed the removal of these substituents. Mechanical performance of the composites was evaluated via static and dynamic tests. The tensile strength and modulus improved 24.9% and 13.6% respectively with the addition of 10 wt% SDS. The flexural strength and modulus also showed an improvement of 22.4% and 26.3% respectively when 10 wt% SDS was added to alkali solution. Dynamic mechanical tests showed that the storage and loss modulus of the composites increase with SDS/alkali treatment. Results indicated that the use of SDS in alkali treatment notably improves the composite performance which is attributable to more efficient elimination of noncellulosic constituents from fiber structure. Highlights: Sodium dodecyl sulfate (SDS) improves the efficacy of NaOH treatment of hemp.Removal of noncellulosic substances from fibers was facilitated by SDS.Ultrasound/SDS assisted alkalization of fibers improved composite properties. [ABSTRACT FROM AUTHOR]

In recent decades, natural fiber reinforced composites (NFRCs) have become an attractive substitute for conventional materials such as glass fiber and have attracted considerable interest from researchers and academics, particularly in the context of environmental protection. Environmental factors and their impact on the fundamental properties of renewable materials are becoming an increasingly popular area of study, particularly natural fibers and their composites. While this area of research is still expanding, natural fiber-reinforced polymer composites (NFRCs) have found widespread use in a variety of engineering contexts. Natural fibers (NFs) such as pineapple leaf (PALF), bamboo, abaca, coconut fibers, jute, banana, flax, hemp, sisal, kenaf, and others have many desirable properties, but their development and use present researchers with a number of obstacles. These fibers have attracted attention due to their various advantageous properties, such as lightness, economy, biodegradability, remarkable specific strength, and competitive mechanical properties, which make them promising candidates for use as biomaterials. As a result, they can serve as alternative materials to traditional composite fibers such as glass, aramid, and carbon in various applications. In addition, natural fibers have attracted the interest of an increasing number of researchers because they are readily available in nature and as by-products of agricultural and food systems, contributing to the improvement of the environmental ecosystem. This interest coincides with the search for environmentally friendly materials to replace synthetic fibers used in the construction, automotive, and packaging industries. The use of natural fibers is not only logical but also practical, as their fibrous form can be easily extracted and strengthened by chemical, physical, or enzymatic treatments. This article provides a brief overview of NFRCs, looking at their chemical, physical, and mechanical properties. It also highlights some of the significant advances associated with NFRCs from an economic, environmental, and sustainability perspective. Additionally, it provides a concise discussion of their diverse applications, all with a focus on their positive impact on the environment. [ABSTRACT FROM AUTHOR]

This review examines the fire retardant potential of natural fiber-reinforced polymer composites derived from plant fibers such as sisal, jute, hemp and coir etc. While these materials offer eco-friendly and cost-effective advantages, their inherent flammability remains a concern. The study consolidates various methodologies employed in evaluating the fire performance of these composites, encompassing cone calorimetry, Limiting Oxygen Index (LOI) test, UL-94 vertical burning test, Thermal Gravimetric Analysis (TGA), and smoke density test, which have been extensively discussed in prior literature. However, despite this coverage, there exists a gap in the lack of standardized evaluation methods and comprehensive studies addressing real-world conditions. To address these gaps, this review critically analyzes the existing research landscape and proposes strategies for improvement. It emphasizes the necessity for standardized testing protocols and comparative studies using uniform methodologies to enable direct comparisons among studies. Furthermore, the review suggests investigating the effects of environmental factors (humidity, temperature, UV exposure, and aging) on fire resistance and emphasizes longitudinal studies to assess the stability and durability of fire retardant treatments over extended periods. Additionally, it explores emerging eco-friendly fire retardant materials and nanotechnologies, highlighting their potential to enhance flame retardancy in natural fiber-reinforced polymer composites, while calling for further evaluation of their efficacy, compatibility, and environmental impact in future research endeavors. Through this, the review aims to bridge the gap between existing knowledge and practical application in improving the fire retardant properties of these composites for sustainable and safer material development. Fire retardant potential of natural fiber-reinforced polymer composites reviewed. Plant fibers like sisal, jute, hemp and coir used as reinforcement in polymer composites. Flammability concerns limit use in critical fire safety applications. Enhancement methods: fire retardant chemicals, coatings, and inorganic fillers. Challenges and future directions in improving fire retardancy discussed. Importance of developing eco-friendly and safe materials for various industries. [ABSTRACT FROM AUTHOR]

Wood Textile Composites (WTCs) represent a new and innovative class of materials in the field of natural fiber composites. Consisting of fabrics made from willow wood strips (Salix americana) and polypropylene (PP), this material appears to be particularly suitable for structural applications in lightweight construction. Since the threads of the fabric are significantly oversized compared to classic carbon or glass rovings, fundamental knowledge of the mechanical properties of the material is required. The aim of this study was to investigate whether WTCs exhibit classic behavior in terms of fiber composite theory and to classify them in relation to comparable composite materials. It was shown that WTCs meet all the necessary conditions for fiber-reinforced composites in tensile, bending, and compression tests and can be classified as natural-fiber-reinforced polypropylene composites. In addition, it was investigated whether delamination between the fiber and matrix can be simulated by using experimentally determined mechanical data as input. Using finite element analysis (FEA), it was shown that the shear stress components of a stress tensor in the area of the interface between the fiber and matrix are responsible for delamination in the composite material. It was also shown that the resistance to shear stress depends on the geometric conditions of the reinforcing fabric. [ABSTRACT FROM AUTHOR]

The objective of this work is to investigate the influence of the utilization of dammar gum (DG), which is a biodegradable and renewable binder, on the mechanical properties of short pineapple leaf fiber (PALF) reinforced tapioca biopolymer (TBP). Samples with variable DG concentrations (10%, 20%, 30%, and 40% by weight) and a constant 30% PALF composition were created with varying TBP percentages using an internal mixing process and compression molding. The results showed that PALF‐TBP with 10% DG had the highest mechanical properties with tensile, flexural, and impact strength of 19.49 MPa, 18.53 MPa and 13.79 KJ/m2, respectively. Scanning electron microscopy (SEM) images prove the enhanced mechanical characteristics. In addition, Fourier transform infrared spectroscopy (FTIR) analysis showed that the DG improves the matrix and PALF interface. The results show that the utilization of DG significantly enhanced the mechanical characteristics of composites. In addition, it is anticipated that it will be able to create PALF‐TBP‐DG composites as a potential alternative for conventional polymers in various applications, especially in engineering applications such as automotive and packaging industries. Therefore, it is expected to be capable of contributing to sustainable development goals (SDGs). Highlights: Recent studies show that damar gum (DG) has potential as a sustainable binder.Optimal composition is a critical factor in bio‐composite manufacturing.The mechanical properties improved the most when 10 wt% of DG was applied.DG could serve as a viable substitute for petroleum‐derived coupling agents.Bio‐composites may serve as alternative polymers for forthcoming applications. [ABSTRACT FROM AUTHOR]

The production of synthetic materials emits harmful gases, driving researchers to seek eco-friendly alternatives, leading to increased demand for natural fiber-based composites in various industries. With advantages like cost-effectiveness, renewability, and biodegradability, natural fiber reinforced composites gain popularity in concrete applications. Their use in concrete has gained global acceptance for its smaller carbon footprint, reduced energy consumption, and minimized wastage. This research aims to evaluate the suitability of Eulaliopsis binata (EB) fiber in mortar and concrete applications. Mortar samples were prepared using different proportions of alkaline-treated EB fibers (0%, 0.25%, 0.5%, 0.75%, 1% and 1.25% by total weight of mortar) in a cement-sand-water mixture with a 1:1:0.35 ratio. Additionally, concrete with a mix proportion of 1:2.15:3.13 (cement: fine aggregate: coarse aggregate) and a water-cement ratio of 0.618 was prepared. The flexural strength test was conducted using plain concrete as well as concrete with untreated and epoxy-treated EB fiber bars of varying diameters. The results revealed that EB fiber-reinforced mortar exhibited a notable increase in flexural and splitting tensile strength, with a 10.85% and 6.23% improvement compared to plain mortar at 0.75% EB fiber content, while compressive strength decreased. Similarly, concrete reinforced with untreated and epoxy-coated EB fiber bars of 14 mm diameter demonstrated 12.32% and 13.27% higher flexural strength, respectively, than that of unreinforced concrete. These results highlight the potential for affordable green concrete production, supporting sustainable infrastructure development. The EB fiber usage presents an encouraging pathway for environmentally conscious construction practices with reduced environmental impact.

Bamboo fiber was extracted after alkaline treatment, and the mechanical properties of fibers and polymer composites were measured. The results showed that the strength of bamboo fiber was higher when the diameter was smaller. Smaller diameter bamboo fibers were dense, while larger diameter ones were composed of vascular bundles, which contained inside voids and outside parts having insufficient lignification. Tensile tests were conducted on bamboo fibers after heating at constant temperatures, and a significant decrease in mechanical properties was observed at heating temperatures above 250 °C. Bamboo fibers were compounded with PE, PA12, ABS, PA6, and biobased PC (Durabio), and injection-molded to prepare the composite specimens for flexural testing. The composite of polyethylene with 30 wt% bamboo exhibited considerably high flexural modulus compared to pure PE. Nevertheless, a large plastic deformation, which was equivalent to that of pure PE was observed. In other polymer composites, those flexural moduli increased, and degree of plastic deformation decreased dramatically, leading to brittleness. For PA6, which was molded above 250 °C, the increment in flexural modulus by fibers was less than the other composites due to the thermal decomposition of the fibers.

The main factors in the ballistic impact mechanism, an incredibly complicated mechanical process, are the target material's thickness, toughness, strength, ductility, density, and projectile parameters. Creating resilient, high-strength, and high-modulus fibers has made it possible to use natural fibers and their composite laminates for various impact-related applications today. Kinetic energy absorption, penetration depth, and residual velocity were the parameters affecting the performance of natural fiber composites used in the armor systems. This review aims to comprehend the several influencing factors that significantly impact the target's ballistic impact performance. In addition to experimental study efforts, many analytical, numerical modeling, and empirical technique-based research approaches have also been considered while analyzing the various components. The paper also examines several factors that determine how well natural fiber composite functions, including internal factors like material composition, characteristics of matrix and reinforcement, the kind and choice of fiber/matrix, failure modes, impact energy absorption, and external factors such as residual velocity, and various projectile nose angles. It also emphasizes the ways to improve composites for high performance and ballistic efficiency, as well as the economic cost analysis of switching out synthetic fibers for natural ones in a ballistic composite.

Natural fiber‐reinforced composites are showing promising results compared to synthetic fiber‐reinforced composites. Therefore, the present work highlights the utilization of chemically treated bamboo‐fiber (BF) for the preparation of bamboo‐fiber high‐density polyethylene composites (BF/HDPE). Both virgin HDPE and recycled HDPE (r‐HDPE) are considered for the preparation of bamboo fiber (BF) composite and their physico‐mechanical properties are evaluated. On alkali and stearic acid treatment, more fibrillation and surface roughness are observed in the BF surface which created more contacting surfaces to improve the interfacial interaction between the BF and HDPE & r‐HDPE matrix. The tensile strength of stearic acid‐treated BF/HDPE is increased by 9.26% and stearic acid‐treated BF‐ rHDPE shows an increment of 16.5%. Similar observations are made for impact strength which confirms the improved dispersion of BF in both matrices. The improved interfacial bonding between BFs and HDPE matrix and good dispersion between fibers and matrix can further be confirmed through the SEM images of composite fractured surfaces and FTIR analysis. Highlights: Surface of BF has been modified by NaOH and stearic acid treatment.Modified fibers are used as reinforcement in virgin and r‐HDPE composites.Stearic acid treatment enhances the tensile strength of composites.Surface modification has significant impact on r‐HDPE composites. [ABSTRACT FROM AUTHOR]

The current research aims to develop a sound‐absorbing material from polypropylene (PP) and sisal fibers (SFs). The study explores the foam processability of PP/SF composites with near‐critical fiber length, employing supercritical CO2‐assisted batch foaming technology. Optimized foam processing conditions were determined to be 145°C, 100 bar, and 15 min saturation time. These conditions resulted in foams with the lowest density, maximum volume expansion ratio and an overall microcellular structure. Notably, increasing the fiber concentration significantly enhanced the compressive properties, exhibiting a remarkable 3000% improvement with the addition of 40 wt% SFs. Dynamic mechanical analysis further revealed improved dampening properties of the composites after foaming. Moreover, the incorporation of SFs led to an increase in the noise reduction coefficient, while foaming additionally improved the sound absorption properties. This renders the material highly applicable for soundproofing purposes. Thus, produced PP/SF microcellular foams offer properties that can potentially be used to produce lightweight structural components for acoustic absorption applications. [ABSTRACT FROM AUTHOR]

Bamboo fiber was extracted after alkaline treatment, and the mechanical properties of fibers and polymer composites were measured. The results showed that the strength of bamboo fiber was higher when the diameter was smaller. Smaller diameter bamboo fibers were dense, while larger diameter ones were composed of vascular bundles, which contained inside voids and outside parts having insufficient lignification. Tensile tests were conducted on bamboo fibers after heating at constant temperatures, and a significant decrease in mechanical properties was observed at heating temperatures above 250 °C. Bamboo fibers were compounded with PE, PA12, ABS, PA6, and biobased PC (Durabio), and injectionmolded to prepare the composite specimens for flexural testing. The composite of polyethylene with 30 wt% bamboo exhibited considerably high flexural modulus compared to pure PE. Nevertheless, a large plastic deformation, which was equivalent to that of pure PE was observed. In other polymer composites, those flexural moduli increased, and degree of plastic deformation decreased dramatically, leading to brittleness. For PA6, which was molded above 250 °C, the increment in flexural modulus by fibers was less than the other composites due to the thermal decomposition of the fibers. [ABSTRACT FROM AUTHOR]

The use of asbestos in brake pads is being eliminated due to its carcinogenic effect. Due to this, there is a need for better alternative in the brake pad material to replace asbestos fibers. This leads to the development of more natural fibers/filler-based brake pads which are safer to the environment, cheaper, and readily available. Moreover, bio fillers-based brake pads have shown excellent performance compared to asbestos. This paper addresses the different composition of brake pad materials and manufacturing techniques. Common binders like epoxy resin, Phenolic resin-based brake pads were analyzed and its effect on the mechanical, tribological, and thermal performance were critically analyzed. Also, the performance of metal matrix-based brake pad has been analyzed in detail. It has been observed that utilizing natural fibers as a reinforcement provides an excellent braking performance compared to metallic and carbon fiber-based brake pads. This research will open new avenues towards "Net Zero." [ABSTRACT FROM AUTHOR]

The use of paddy straw (PS) is proposed in this research as a reinforcing filler for manufacturing reinforced polymeric composite using polypropylene (PP) and could present a cost-effective and feasible substitute for conventional wood-based plywood. The PS/PP composites could potentially offer a sustainable solution by virtue of the abundance and renewability of this waste biomass and huge quantities of recyclable segregated polymer from solid waste processors. The short-fiber-reinforced paddy straw composites were manufactured using the injection molding technique—which could be supportive for industry-scale production with high reliable quality and design flexibility. The composites were characterized systematically—where the 60:40 wt% ratio of PS: PP was the optimum. The shock resistance positively correlated with fiber loading with a maximum value of 2818 J/m2. The tensile and flexural strengths were found to be maximum at 60 wt% of fiber loading. The developed PS/PP composites exhibited low water absorption as compared to their wood counterparts—which could be beneficial for their application in furniture, insulators, packaging, and interiors in the housing sector. Further, the valorization of paddy straw can potentially diminish the present practice of open-burning of this agricultural residue. Thus, the gainful utilization of paddy straw could offer multiple benefits, including a reduction in GHG emissions and deforestation. This innovation can potentially contribute to achieving the UN's sustainable development goals, including Climate Action (SDG 13), Responsible Consumption and Production (SDG 12), Decent Work and Economic Growth (SDG 8), and Industry, Innovation, and Infrastructure (SDG 9). [ABSTRACT FROM AUTHOR]

The present research is aimed at examining the changes in tensile and compressive properties of natural fiber-reinforced composites (NFRC) exposed to various humidity conditions; this is due to the fact that moisture content (MC) in fibers is generally assumed to be detrimental to composite performance. It was found that once moisture is exposed, compressive strength and strain of specimens would be higher than those of tensile, whereas modulus of elasticity would be lower. Due to increasing moisture content, although elongation in all tests was enhanced, tensile and compressive strength declined by 15% and modulus of elasticity decreased by 20%. In addition, Poisson's ratio for both compressive and tensile properties was nearly identical (0.33) in distinct moisture content. A new understanding of moisture's effects on mechanical behavior is presented in this study by finding an optimum point for exposing moisture to increase compressive and tensile strength. [ABSTRACT FROM AUTHOR]

The main factors in the ballistic impact mechanism, an incredibly complicated mechanical process, are the target material's thickness, toughness, strength, ductility, density, and projectile parameters. Creating resilient, high-strength, and high-modulus fibers has made it possible to use natural fibers and their composite laminates for various impact-related applications today. Kinetic energy absorption, penetration depth, and residual velocity were the parameters affecting the performance of natural fiber composites used in the armor systems. This review aims to comprehend the several influencing factors that significantly impact the target's ballistic impact performance. In addition to experimental study efforts, many analytical, numerical modeling, and empirical technique-based research approaches have also been considered while analyzing the various components. The paper also examines several factors that determine how well natural fiber composite functions, including internal factors like material composition, characteristics of matrix and reinforcement, the kind and choice of fiber/matrix, failure modes, impact energy absorption, and external factors such as residual velocity, and various projectile nose angles. It also emphasizes the ways to improve composites for high performance and ballistic efficiency, as well as the economic cost analysis of switching out synthetic fibers for natural ones in a ballistic composite. [ABSTRACT FROM AUTHOR]

Robotic coreless filament winding using alternative material systems based on natural fibers and bio-based resin systems offers possible solutions to the productivity and sustainability challenges of the building and construction sector. Their application in modular, prefabricated structures allows for material-efficient and fast production under tightly controlled conditions leading to high-quality building parts with minimal production waste. Plant fibers made of flax or hemp have high stiffness and strength values and their production consumes less non-renewable energy than glass or carbon fibers. However, the introduction of natural material systems increases uncertainties in structural performance and fabrication parameters. The development process of coreless wound composite parts must thus be approached from the bottom up, treating the material system as an integral part of design and evaluation. Existing design and fabrication methods, as well as equipment, are adjusted to emphasize material aspects throughout the development, increasing the importance of material characterization and scalability evaluation. The reciprocity of material characterization and the fabrication process is highlighted and contributes to a non-linear, cyclical workflow. The implementation of extensions and adaptations are showcased in the development of the livMatS pavilion, a first attempt at coreless filament winding using natural material systems in architecture. [ABSTRACT FROM AUTHOR]

Hybridization of natural and synthetic fibers in a single composite material can be made by several means, and one of the best methods is the intra-ply in which both fibers are woven within a single layer. Through hybridization, the advantages of one type of fiber can improve the limitations of the other. Further the blending of natural and synthetic fibers leads to the fabrication of composites with higher mechanical performance. Hence, this work focuses on the fabrication of intra-ply Kevlar and hemp fiber reinforced epoxy hybrid composites with different weaving patterns such as plain weave, basket weave, and twill weave type. Yarns were woven by handloom technique to make intra-ply Kevlar and hemp fiber mats, and the composites were fabricated by compression molding. The water absorption, thickness swelling, and solid particle erosion characteristics of the composites were examined. The results of the experiments showed that the hemp fiber composites exhibited the least resistance (8.45% change in absorption and 4.34% change in thickness) towards the absorption and swelling, whereas pure epoxy (0.67% change in absorption and 0.31% change in thickness) and Kevlar (2.67% change in absorption and 1.67% change in thickness) composites possessed higher resistance. The absorption and swelling performance of all other hybrids was found to be in between the hemp and Kevlar composites hence proving the effectiveness of the hybridization. Further, Taguchi’s experimental design results indicated that the basket weave type hybrid composites had a minimal erosion rate for 2 minutes of exposure duration and an impact angle of 90°. The morphological analysis of the eroded surfaces of composites revealed the presence of micro cavities, broken fibers, crater formation, and microcracks.

Synthetic fiber is still considered the best sound absorptive material. However, due to the health concern of synthetic fiber usage, researchers are trying to find another viable alternative. A microperforated panel (MPP) is a promising alternative that relies on the concept of a Helmholtz resonator for sound absorption. MPP possessed excellent acoustic resistance and a considerable range of absorption bandwidth. In this paper, MPP made of natural fiber composite was fabricated and its acoustic absorption was measured using a two-microphone impedance tube method as per ISO 10534-2 standard. Later, the tensile strength of the fabricated acoustic absorbers was measured using an Instron Universal Testing Machine as per ASTM D638. The idea of employing additive manufacturing, better known as the 3D printing technique, is proposed to produce lightweight MPP. The 3D printing technique provides design freedom and is less tedious in creating complex and light structures. The 3D printing technique has various important parameters, and infill density is one of the parameters. It was found that the reduction of infill density leads to a decrease of the MPP’s mass and thus, slightly affects the resonance frequency of the MPP, still within the mid-frequency spectrum. It was also noted that the increment of air gap thickness leads to the shifting of MPP’s resonance frequency to a lower frequency range. The tensile strength of the 3D printed samples decreases with a decrease in infill density. A sample with an infill density of 100% has the highest tensile strength of 22 MPa, and a sample with an infill density of 20% has the lowest tensile strength of 12 MPa.

The effect of tightening torque and washer size on the performance of basalt natural fiber composite joints was investigated experimentally. It was found that washer size is the main design driver in controlling the out-of-plane behavior of the joint. Specifically, there was a 36.5% increase in the 0.2% offset strength when the torque was increased for small washer configurations, whereas a 42% increase was observed when the torque was increased for large washer configurations. Moreover, the ultimate bearing strength also showed an improvement under the combined effect of washer size and tightening torque. Additionally, damage onset and failure mechanisms of the bolted joint were investigated using optical microscopy. The morphological observations indicated excessive crushing for large washer configurations. It is postulated that bearing performance could be improved by choosing appropriate washer size and tightening torque.

There is a remarkable increase in natural fiber-reinforced composites research over the last three decades due to their abundance, less density, biodegradability, renewable sources, and low cost. The fabrication of natural fiber composites require less energy when compared with synthetic fiber composites. Various natural fibers are available globally and have been used as reinforcements in polymer composites. These fibers provide comparable properties and can be considered as a substitute for synthetic fiber composites. The objective of this review is to analyze the various types of natural fibers used in composite fabrication along with their physical, chemical, mechanical, thermal, and tribological properties. Other important aspects such as fiber extraction, chemical treatments, manufacturing methods, hybridization, interfacial adhesion, and applications for different natural fiber composites are also discussed. The review also establishes the scope of natural fiber composites for future needs in various applications by understanding their merits and demerits.