Fabrication and characterization of silanized echinoidea fillers and kenaf fibre-reinforced Azadirachta-indica blended epoxy multi-hybrid biocomposite

Fabrication and characterization of echinoidea spike particles and kenaf natural fibre-reinforced Azadirachta-Indica blended epoxy multi-hybrid bio composite

This paper aims to fabricate a novel kenaf fiber, glass fiber, graphene composite reinforced with epoxy, and to study its water absorption, mechanical and machining properties. Natural fiber composites seek numerous applications nowadays due to its high strength is to weight ratio, high impact resistance, thermal stability, and recyclability. The literature study on natural fiber composites indicates lack of research on Kenaf fibers reinforced with E-glass fibers in conjunction with 0.5% and 1.0% of graphene. Hence, this research focuses on Kenaf fiber with percentage composition of graphene was varied as 0.5%, and 1.0%, by weight of the holding matrix and with/without incorporation of glass fiber. Suitable surface modifications were done by treating natural fibres by 0.5% NaOH for better adhesion of fibre and epoxy resin. Sonication and Cetyl trimethyl ammonium bromide (CTAB) treatments were also done to realize the fine scattering of graphene in the epoxy matrix in order to achieve better mechanical behaviour. Moulds were prepared as per D-638 ASTM standards. The treated fibres were then arranged in the mould by the conventional hand layup technique. The main objectives of this study are to conduct tensile, flexural, Impact, water absorption, machinability, and FTIR test. Result shows that the incorporation of graphene in natural fiber composites showed an increase in tensile strength, flexural strength, and water absorption properties by 27.7%, 53%, and 15% on average, respectively. The composites used in this research find their use in potential applications such as defence, biomedical aids, automobiles, packaging, actuators, etc. These often generate great interest, whenever there is a demand for fabricating lightweight and high strength material.

Thermo-mechanical characterization of siliconized E-glass fiber/hematite particles reinforced epoxy resin hybrid composite

This study investigates the incorporation of boron carbide (B4C) filler particulates into a kenaf fiber-reinforced epoxy matrix to explore its potential in lightweight applications, focusing on antimicrobial effectiveness, mechanical integrity, thermal properties, and microstructural characteristics. The composite material was formulated by blending varying seven different concentrations of boron carbide (0–50 g) and kenaf fibers (KFs) with an epoxy resin, aiming to achieve a balance between mechanical strength and minimal weight. Antimicrobial test revealed that the composite material, consisting of kenaf fiber reinforced with B4C particulates, exhibited significant antibacterial activity against common pathogens. Mechanical testing indicated that the addition of boron carbide and kenaf fibers significantly improved the tensile strength and flexural rigidity of the composites. Specifically, enhancements in tensile strength and flexural modulus were quantitatively analyzed, showing notable increases compared to the base epoxy resin. Scanning Electron Microscopy (SEM) was employed to examine the fracture surfaces following mechanical testing, revealing improved interfacial bonding between the kenaf fibers and the epoxy matrix due to the presence of boron carbide. This microscopic analysis also highlighted areas where stress distribution was optimized, contributing to the composite's enhanced mechanical properties.

Thermoplastic and thermoset polymer composites reinforced with kenaf fiber or CaCO<sub>3</sub> have been extensively investigated. However, the study on the combination of kenaf fiber and CaCO<sub>3</sub> reinforced epoxy resin is rare. This research discussed the effect of CaCO<sub>3</sub> particle size and the ratio of kenaf to CaCO<sub>3</sub> content on the impact strength of alkali-treated kenaf/ CaCO<sub>3</sub>/epoxy resin hybrid composites. Thirty % of the hybrid kenaf fibers and CaCO<sub>3</sub> particles reinforced epoxy resin composites were fabricated by hand lay-up technique followed by cold press. Impact test of the composite specimens was conducted using a Charpy Impact test according to ASTM D 6110. The morphology of impact fracture surface was examined by scanning electron microscopy (SEM). The results showed that the impact strength of the hybrid composite increased with the decrease of CaCO<sub>3</sub> particle size, and increasing the ratio of kenaf to CaCO<sub>3</sub>. Interfacial bonding between the reinforcement (kenaf and CaCO<sub>3</sub>) and epoxy resin matrix, the uniform dispersion of kenaf and CaCO<sub>3</sub> within the epoxy resin matrix are two crucial factors influencing the impact strength of the composite.

In this study, the mechanical properties and flexural behaviour of the fibrous cementitious composites containing hybrid, kenaf and barchip fibres cured in cyclic exposure were investigated. Waste or by-product materials such as pulverized fuel ash (PFA) and ground granulated blast-furnace slag (GGBS) were used as a binder or supplementary cementitious to replace cement. Barchip and kenaf fibre were added to enhance the mechanical properties and flexural behaviour of the composites. A seven mix design of the composites containing hybrid, kenaf and barchip fibre mortar were fabricated with PFA-GGBS at 50% with hybridization of barchip and kenaf fibre between 0.5% and 2.0% by total volume weight. The composites were fabricated using 50 × 50 × 50 mm, 40 × 40 × 160 mm and 350 × 125 × 30 mm steel mould. The flexural behaviour and mechanical performance of the PFA-GGBS mortar specimens were assessed in terms of load-deflection response, load compressive response, and crack development, compressive and flexural strength after cyclic exposure for 28 days. The results showed that specimen HBK 1 (0.5% kenaf fibre and 2.0% barchip fibre) and HBK 2 (1.0% kenaf fibre and 1.5% barchip fibre) possessed good mechanical performance and flexural behaviour. As conclusion, the effect of fibres was proven to enhance the characteristics of concrete or mortar by reducing shrinkage, micro crack and additional C-S-H gel precipitated from the pozzolanic reaction acted to fill pores of the cement paste matrix and cement paste aggregate interface zone between mortar matrix and fibre bonding.

Hybrid kenaf/glass fiber reinforced polymer composites have emerged as promising structural materials, garnering significant attention due to their unique blend of natural kenaf fibers and synthetic glass fibers. However, despite their potential, there remains a gap in the comprehensive understanding of their quasi‐static mechanical behavior, creep resistance, and fatigue performance. This paper addresses this gap by presenting recent advancements in studying these key properties of hybrid composites. Studies reveal that the combination of kenaf and glass fibers results in enhanced tensile, flexural, and impact strengths compared to individual fiber composites. Additionally, the hybridization offers improved creep resistance, with the glass fibers reinforcing the polymer matrix against deformation under sustained loads. Furthermore, investigations into fatigue properties demonstrate the resilience of hybrid composites to cyclic loading, contributing to prolonged service life in high‐stress environments. By elucidating the interplay between kenaf and glass fibers, this review underscores the potential of hybrid composites in various structural applications. The synergistic effects between natural and synthetic fibers offer a balance between sustainability, performance, and durability, making hybrid kenaf/glass fiber reinforced polymer composites a compelling choice for industries seeking lightweight, high‐performance materials in which aligns with the sustainable development goals (SDGs) especially on Goal 12. Highlights In composite engineering, combining glass and kenaf fibers could cut production costs, yield high‐performance materials, and promote green technology. Substituting part of the glass fiber with kenaf can enhance the strength‐to‐weight ratio and promote greater biodegradability in current synthetic composites. Quasi‐mechanical properties of hybrid kenaf/glass‐based composites was enhanced by optimal stacking sequences, filler addition, and fiber treatment. Failures due to fatigue and creep can be reduced by hybridizing kenaf/glass fiber composites can prevent in polymer composite due to enhance elastic modulus. Enhanced tribological performance of hybrid kenaf/glass‐based composites due to less damage in microstructure via good interlocking of kenaf and glass in matrix.

To investigate the effect of dimethoxymethylsilyl-terminated polypropylene oxide (DMSi-PPO) elastomer particles on the toughening of epoxy resin, the particles were prepared in liquid bisphenol A-type epoxy resin by means of the dynamic vulcanization method. With the addition of aminosilane (AMS), the fracture energy G1c values of adhesive joints and the T-peel bond strength were more than three times those of the unmodified system without a decrease in Tg. Observations of the modified epoxy resin before curing using a video microscope revealed that the diameter of DMSi-PPO particles decreased and the number of particles increased when the amount of AMS was increased. Scanning electron micrographs of the cured epoxy resin showed that the size of crosslinked DMSi-PPO particles remained the same as before curing. It is concluded that the addition of AMS leads to an increase in the compatibility of DMSi-PPO with epoxy resin matrix and thus the G1c value and the adhesion properties are increased due to the increase in surface area of DMSi-PPO particles. It is also shown that the adhesion property does not depend on the curing condition because the phase structure of the epoxy resin was fixed before the curing of the epoxy resin.

A successful attempt has been made to develop coir fibre composites reinforced with graphene, epoxy and carbon fibre. The carbon fibres were arranged in an intercalated manner, which is similar to the coir fibres. The percentage composition of graphene was varied as 1, 2, 4 and 6% by weight of the holding matrix. Suitable surface modifications were done by treating natural fibres by 5% NaOH and 0.3% KMnO4 for better adhesion of fibre and epoxy resin. Sonication and cetyl trimethyl ammonium bromide treatments were also done to achieve the fine scattering of graphene in the epoxy matrix in order to achieve better mechanical behaviour. Moulds were made as per D638 American Society for Testing and Materials (ASTM) standards. The treated fibres were then arranged in the mould by the conventional hand layup technique. Tensile testing was carried out to determine the mechanical properties of the composites. Two-way analysis of variance was used as a statistical tool to find the effect of parameters such as ‘Percentage composition of graphene’ and ‘Type of mould’ on the modulus of the composites. Fourier transform infrared spectroscopy was conducted to determine the interferential adhesion and homogeneous distribution of fibres in the composite matrix. At last, field emission scanning electron microscopy analyses were also done to the specimens before and after tensile testing to determine the morphology of different entities present in the composites.

Low velocity impact behaviour and post-impact characteristics of kenaf/glass hybrid composites with various weight ratios

- The increasing demand for lightweight, sustainable, and high-performance materials has accelerated the development of natural fiber–reinforced composites. This study investigates the mechanical behaviour and performance evaluation of kenaf–sisal hybrid composite materials fabricated using epoxy resin as the matrix. Kenaf fibers contribute high tensile strength, while sisal fibers enhance toughness and durability, resulting in a balanced hybrid composite system. The composites were fabricated through the hand lay-up technique followed by controlled compression and curing to achieve uniform thickness and improved fiber–matrix bonding. Mechanical characterization was carried out using tensile, flexural, and impact tests in accordance with ASTM standards to evaluate strength, stiffness, and energy absorption capability. In addition, scanning electron microscopy (SEM) was employed to examine fiber distribution, interfacial bonding, and fracture mechanisms. The results demonstrate that the kenaf–sisal hybrid composite exhibits improved mechanical performance compared to single-fiber composites, with enhanced load-bearing capacity and impact resistance. SEM observations confirmed effective resin impregnation and strong fiber–matrix adhesion, contributing to improved mechanical behaviour. The developed hybrid composite offers a lightweight, eco-friendly, and cost-effective alternative to conventional synthetic composites, making it suitable for applications such as automotive interior components and structural panels. Key Words: Kenaf fiber; Sisal fiber; Hybrid composite; Natural fiber reinforced polymer; Mechanical behaviour; Tensile strength; Flexural strength; Impact resistance; Epoxy matrix; SEM analysis; Sustainable materials; Automotive applications

This paper investigates the influence of silica nanoparticles on the mechanical properties of a unidirectional (UD) kenaf fiber reinforced polymer (KFRP) and hybrid woven glass/UD kenaf fiber reinforced polymer (GKFRP) composites. In this study, three different nanosilica loadings, i.e., 5, 13 and 25 wt %, and untreated kenaf fiber yarns were used. The untreated long kenaf fiber yarn was wound onto metal frames to produce UD kenaf dry mat layers. The silane-surface-treated nanosilica was initially dispersed into epoxy resin using a high-vacuum mechanical stirrer before being incorporated into the UD untreated kenaf and hybrid woven glass/UD kenaf fiber layers. Eight different composite systems were made, namely KFRP, 5 wt % nanosilica in UD kenaf fiber reinforced polymer composites (5NS-KFRP), 13% nanosilica in UD kenaf fiber reinforced polymer composites (13NS-KFRP), 25 wt % nanosilica in UD kenaf fiber reinforced polymer composites (25NS-KFRP), GKFRP, 5 wt % nanosilica in hybrid woven glass/UD kenaf fiber reinforced polymer composites (5NS-GKFRP), 13 wt % nanosilica in hybrid woven glass/UD kenaf fiber reinforced polymer composites (13NS-GKFRP) and 25 wt % nanosilica in hybrid woven glass/UD kenaf fiber reinforced polymer composites (25NS-GKFRP). All composite systems were tested in tension and bending in accordance with ASTM standards D3039 and D7264, respectively. Based on the results, it was found that the incorporation of homogeneously dispersed nanosilica significantly improved the tensile and flexural properties of KFRP and hybrid GKFRP composites even at the highest loading of 25 wt % nanosilica. Based on the scanning electron microscopy (SEM) examination of the fractured surfaces, it is suggested that the silane-treated nanosilica exhibits good interactions with epoxy and the kenaf and glass fibers. Therefore, the presence of nanosilica in an epoxy polymer contributes to a stiffer matrix that, effectively, enhances the capability of transferring a load to the fibers. Thus, this supports greater loads and improves the mechanical properties of the kenaf and hybrid composites.

This paper is focused on developing composites using kenaf fibers, epoxy polymer, and incorporation of graphene fillers. The kenaf fibers are treated with 5% NaOH to remove the hydrophilic nature and reinforced it with the hydrophobic matrix. The composites are fabricated using the compression moulding technique by keeping 60 wt.% epoxy as constant, and the graphene and kenaf fiber weights are changed accordingly. The samples for tensile, flexural, impact, hardness, and water absorption tests are prepared as per the ASTM D3039, D790, D256, D2240, and D572 standards, respectively. The effect of graphene fillers in the 5% NaOH‐treated kenaf fibers reinforced with the epoxy matrix is tested. Among the various samples, sample 4 which has 6% graphene addition in the epoxy matrix reinforced with 5% treated kenaf fiber displayed the highest tensile strength of 63 MPa, flexural strength of 97 MPa, impact strength of 9.56 kJ/m2, hardness value of 97, and lower water absorption of 5.13%. This is due to the proper dispersion of graphene fillers in the matrix which caused better interfacial adhesion between the fiber and matrix. The water absorption test showed the lowest value in sample S5 as the graphene fillers obstruct water penetration in the fibers. SEM analysis is done on the prepared samples to study the surface flaws and structural changes.

Epoxy bio composite was prepared using areca fibre, nano-silica and toughened by neem oil bio blender (anti-microbial content) for various engineering applications. The principal aim of this research work is to reveal the need and importance of adding nano-silica particles (a natural antibacterial substance) into neem oil when it is blended with epoxy resin to form a bio-composite. The nano-silica particle and areca fibre have been surface-treated by an amino silane 3-Aminopropyltriethoxysilane (APTES) for better dispersion on neem-epoxy blended matrix medium. The composites were prepared using hand layup method with post-cured at 120 °C in a hot oven. The composites have been tested in accordance with ASTM standards. The visco-elastic analysis shows that the storage modulus of 2 vol.% of nano-silica particles in 30 vol.% of areca-reinforced epoxy-neem composite found to be higher up to 9.8 GPa at room temperature and 1.8 GPa at 120 °C. The loss factor also found to be higher at the glass transition temperature. The differential scanning calorimetry results showed that the composites contain 2 vol.% of nano-silica particles retains the glass transition (Tg) at higher neem oil blending (20 vol.%) as higher than epoxy resin. The antimicrobial behaviour of neem-epoxy composite was increased by the addition of 2 vol.% of nano-silica. Finally, the electrical insulation studies revealed that the composites built with non-polar neem oil and partial polar nano-silica not altered the electrical resistance much. These antimicrobial enhanced and thermo-mechanically strengthened epoxy bio composites could be used as food storage containers, medical components carrier and domestic appliance manufacturing.

Polyester and epoxy resins are thermosetting polymers extensively used as composite materials matrices. The advantage of the polyester resin in comparison with the epoxy matrix is its lower cost. On the other hand, its permeability can be considered a disadvantage, once as the solvents dry the resin becomes more porous. This represents a direct impact on its mechanical properties. Epoxy resin has no solvents and its polymerization occurs only when two components are mixed, resin and hardener. The processing of this type of polymer requires control of temperature and humidity during its production. Polyester resin continues to cure over time, are prone to cracking and breaking, while epoxy resin once cured retains its full properties. The current pullout tests were performed to compare the interfacial adhesion of fique fibers with epoxy and polyester polymer matrix. The results indicated a critical length approximately 65% higher for the fique fiber/polyester in comparison to fique fiber/epoxy as well as an interfacial strength 4.9 times higher, which may indicate stronger adhesion of fique fiber with epoxy resin.