Epoxy Composites Research Articles

Optimizing dielectric constant of noncommercial biobased fibres - Acacia Nilotica, Acacia Leucophloea and Prosopis juliflora - For composite applications with selected fillers

In recent decades, most electrical/electronic products possess non – biodegradable components. The expanding consumption of these goods and their eventual disposal pose a serious environmental threat. To cope up with this issue, biodegradable electrical/electronic components using biobased fibres can be an alternative option. The novel exploration of this research work is the usage of underutilized biobased fibres, such as Acacia Nilotica, Acacia Leucophloea and Prosopis Juliflora, as sustainable alternatives to traditional synthetic fibres in natural fibre-reinforced epoxy composites. The novelty lies in the combination of these natural fibres with ceramic fillers like Silicon Carbide, Boron Nitride and Aluminium Oxide, aiming to enhance the composite properties. The objective of the study is to optimize the type of fibre, fibre content (2 wt%, 4 wt% and 6 wt%) and types of fillers (1 wt%) combinations using the Box-Behnken Design to improve the dielectric properties of these composites. Analysis of Variance (ANOVA) is used to evaluate the relevance of each parameter on dielectric constant of the biobased fibre reinforced epoxy composite. The significant outcome is identified that Prosopis Juliflora (6 wt%) combined with Boron Nitride (1 wt%) yields an optimal dielectric constant of 1.11, highlighting the potential of these biobased fibres to serve as effective substitutes for conventional glass and carbon fibres for electrical insulating materials used in switchboards and socket pins to prevent electrical conduction and ensure safety. This research not only contributes to the field of sustainable materials but also addresses critical environmental concerns associated with electric/electronic waste.

Influence of Calcination and Cation Exchange (APTES) of Bentonite-Modified Reinforced Basalt/Epoxy Multiscale Composites’ Mechanical and Wear Performance: A Comparative Study

In this study, bentonite clay was modified through silane treatment and calcination to enhance its compatibility with basalt fiber (BF) and epoxy in multiscale composites. The as-received bentonite (ARB) was subjected to silane treatment using APTES, producing silane-modified bentonite (STB), while calcination yielded calcined bentonite (CB). The modified clays were incorporated into basalt fiber-reinforced epoxy (BFRP) composites, which were fabricated using the vacuum-assisted resin transfer method (VARTM). Analytical techniques, including X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy, confirmed the structural changes in the clays. BET surface area analysis revealed a 314% increase in the surface area of STB and a 176% increase for CB. The modified clays also demonstrated reduced hydrophilicity and swelling behavior. Thermogravimetric analysis (TGA) indicated a minimal improvement in thermal stability, with the degradation onset temperatures increasing by less than 3 °C. However, tensile tests showed significant gains, with CB- and STB-reinforced composites achieving 48% and 21% higher tensile strength than ARB-reinforced composites. Tribological tests revealed substantial reductions in wear, with CB- and STB-reinforced composites showing 90% and 84% decreases in the wear volume, respectively. These findings highlight the potential of modified bentonite clays to improve the mechanical and wear properties of basalt fiber–epoxy composites.

Mechanical Performance on Flax Fibre Epoxy Composites Filled with Montmorillonite Nanoclay for Lightweight Applications

The objective of this study is to investigate the mechanical performance on develop flax/epoxy composite filled with montmorillonite nanoclay for lightweight applications. For this purpose, firstly, nanoclay at different weight percentages montmorillonite nanoclay such as 0.5, 1, 1.5 was dispersed homogeneously into epoxy resin with the help of ultrasanitization process. For better nanoclay distribution in composite, the montmorillonite nanoclay concentration higher than 1.5% was not analyzed. Secondly, using this mixture, flax fiber based composites were produced by vacuum bag molding process. Finally, the mechanical properties of flax/epoxy composites filled with different percentages montmorillonite nanoclay were determined with tensile, flexural, and in-plane shear test. From the experimental results obtained, the addition of montmorillonite nanoclay indicate positive effect on the performance of the composites compared with the neat composite samples, if the montmorillonite nanoclay distribute homogeneously in the epoxy. The composites added with 0.5 wt.% nanoclay showed the highest tensile modulus and tensile strength. Moreever, the elasticity modulus of composite samples with 0.5% nanoclay addition is approximately 87% higher than the pure composite. Also, the composite samples loaded with 1.5 wt.% of montmorillonite nanoclay performs better under flexural loading conditions.

Exploring mechanical properties of eco-friendly hybrid epoxy composites reinforced with sisal, hemp, and glass fibers

It is now widely accepted that various subsets of hybrid fiber composites reinforced with combined natural and synthetic fibers can significantly expand the applicability of composite-based materials in design and technology practice. The already existing unnatural circumstances on the planet put natural fibers far ahead of traditions in the field of materials thanks to their biodegradability characteristics, availability and over-term endurance and corrosion resistance. At the same time, composites are rapidly taking their place in many industries and sectors of the economy as metals in as much as it is economically and energetically justified. This study evaluates the mechanical properties of hybrid composites reinforced with glass, hemp, and sisal fibers. Using a hand lay-up method with epoxy resin, composite laminates were fabricated and tested for tensile, flexural, impact strengths and hardness test in accordance with ASTM standards. The experimental results revealed that glass-sisal fiber composites achieved the highest tensile strength of 69.1 MPa, while glass-hemp-sisal fiber composites exhibited superior flexural strength of 15.22 MPa and impact strength of 137.45 kJ/m2 while best hardness value was 24.73 HV for glass-sisal fibre composite. These findings underscore the potential of glass-sisal-hemp fiber-reinforced epoxy composites as viable alternatives to traditional synthetic fiber-reinforced materials in automotive industry where there are no structural loadings i.e. automobile interiors; offering enhanced mechanical performance and sustainability.

Hydrogen-bonded organic framework for fire-safe epoxy composite with photochromic properties and rapid de-icing capability

Multifunctionalized epoxy resin (EP) composites are essential for advancing technological innovation across various applications. One efficient method to achieve this is through the development of multifunctional EP fillers. In this work, 2,4,6-tri(pyridin-4-yl)pyridine (Tripp) as electron acceptor and phosphoric acid as electron donor are self-assembled to form a donor–acceptor (D-A) type hydrogen-bonded organic framework (HOF, named P-HOF) using a solvent volatilization method. P-HOF exhibits excellent photochromic and photothermal properties under 365 nm UV irradiation. Electron paramagnetic resonance (EPR) analysis confirms the generation of viologen radicals, and the internal electron transfer mechanism of P-HOF is further elucidated using X-ray photoelectron spectroscopy (XPS). Furthermore, incorporating 3 wt% P-HOF into EP as a filler results in an EP/P-HOF composite that not only retains excellent photochromic and photothermal properties but also demonstrates rapid de-icing and outstanding flame retardancy. The EP/P-HOF coating demonstrates a de-icing efficiency that is 3.83 times higher than that of pure EP coatings. Compared to pure EP, the EP/P-HOF significantly reduced the peak heat release rate (pHRR), total heat release (THR), and peak smoke production rate (pSPR) by 55.0 %, 19.6 %, and 29.6 %, respectively.

Enhanced Epoxy Composites Reinforced by 3D-Aligned Aluminum Borate Nanowhiskers.

Recently, the durability of high-performance and multifunctional portable electronic devices such as smartphones and tablets, has become an important issue. Electronic device housing, which protects internal components from external stimuli, such as vibration, shock, and electrical hazards, is essential for resolving durability issues. Therefore, the materials used for electronic device housing must possess good mechanical and electrical insulating properties. Herein, we propose a novel high-strength polymer nanocomposite based on 3D-aligned aluminum borate nanowhisker (ABOw) structures. ABOw was synthesized using a facile hydrothermal method, and 3D-aligned ABOw structures were fabricated using a freeze-casting process. The 3D-aligned ABOw/epoxy composites consist of repetitively layered structures, and the microstructures of these composites are controlled by the filler content. The developed 3D-aligned ABOw/epoxy composite had a compressive strength 56.72% higher than that of pure epoxy, indicating that it can provide high durability when applied as a protective material for portable electronic devices.

Mechanical properties of epoxy composites filled with multi-walled carbon nanotube, Nanoaluminum particles and glass fibers at elevated temperatures

The present work investigates the mechanical properties of a composite material composed of multi-walled carbon nanotubes (MWCNTs), nano-aluminum powder (NAP), and glass fibers (GF) for five different compositions. The study further investigated how MWCNTs contribute to maintaining the mechanical properties of nanocomposites when exposed to elevated temperatures, up to 180 °C. The evaluation of impact strength revealed that the nanocomposite, composed of 2 % MWCNTs, 15 % NAP, and 10 % GF, demonstrated the greatest impact strength. At room temperature, the composite containing 2 % MWCNTs, 5 % NAP, and 20 % GF exhibited the highest ultimate tensile strength (UTS). Conversely, at elevated temperatures reaching up to 180 °C, the highest UTS was observed in the composition with 2 % MWCNTs, 10 % NAP, and 15 % GF. The hardness of the nanocomposite was influenced by its composition; at room temperature, the maximum hardness was observed in the mixture containing 2 % MWCNTs, 20 % NAP, and 5 % GF. In contrast, at elevated temperatures, the composition with 2 % MWCNTs, 5 % NAP, and 20 % GF exhibited the highest hardness. Overall, the study found that incorporating GF and NAP improved the mechanical properties of the composite. These results indicate that the composite's performance could be further optimized for specific applications through the addition of filler materials.

Uncovering the attributes of micro-size basalt powder doped epoxy composites: fabrication, characterization, and gamma attenuation properties

Uncovering the attributes of micro-size basalt powder doped epoxy composites: fabrication, characterization, and gamma attenuation properties

EXPERIMENTAL INVESTIGATION ON FREE VIBRATIONAL DAMPING AND DRILLING BEHAVIOR OF FLAX REINFORCED EPOXY COMPOSITES USING ADAPTIVE NEURO FUZZY INFERENCE SYSTEM

Flax reinforced epoxy (F-Ep) composites were prepared by the compression moulding technique, varying the fiber content (0, 25, 35 and 45 wt%). The free vibration test was performed on the neat epoxy and F-Ep composites to understand their dynamic characteristics, and results showed that natural frequency and damping factor of the F-Ep composites increased with an increase in the fiber content. The F-Ep composite (45F-Ep) that exhibited better damping was selected for performing the drilling operation. Factors such as spindle speed (rpm), feed rate (mm/min) and drill point angle (degree) were chosen as input parameters and the tabulated set of experiments were in accordance with Taguchi’s design of experiment. The response measured was thrust force and the obtained values were found in the range of 19.66 to 50.75 N. The minimum value of thrust force was achieved when the F-Ep composite was drilled at high spindle speed (3000 rpm), with a feed rate of 75 mm/min using the drill point angle of 118°. ANOVA analysis showed that the developed regression model was significant and thrust force was mainly influenced by the spindle speed. Mathematical models were developed for drilling F-Ep composite using response surface methodology (RSM) and adaptive neuro fuzzy inference system (ANFIS) and compared for their efficacy.

In situ growth of graphene on carbon fibers to enhance the mechanical and thermal conductivity of epoxy composites

High-strength and high-thermal-conductivity composite materials have become crucial requirements for thermal control systems in various field. Carbon fiber-reinforced polymer (CFRP) has demonstrated potential superior performance. However, the application of CFRP is limited by the chemical inertness of the carbon fiber surface and the shortness of low surface energy. Therefore, surface modification of carbon fibers is necessary. This research employs a pulse plasma discharge method, to in-situ grow graphene on the surface of carbon fibers by disrupting some polymer structures on the carbon fiber surface in a “bottom-up” approach. This method offers advantages such as rapid, simple, convenient, economical, and environmentally friendly preparation process., the modified carbon fibers used in CFRP exhibit superior mechanical and thermal conductivity properties. The flexural strength increased by 218 % to reach 109.5 MPa, and the thermal conductivity increased by 251 % to achieve 1.153 W/(m*K).

Bending Analysis of Multiwall Carbon Nanotube Reinforced Functionally Graded Composite Cylindrical Shell

The curved structural components of aircraft, automobiles, and marine vessels, such as cylindrical panels, are primarily exposed to loading, which can result in bending failure, particularly in lightweight structures. The bending analysis of cylindrical panels made of functionally graded multiwall carbon nanotube (FG-MWCNT) epoxy composites is subjective in this study. In the first section, FG-MWCNT composite cylindrical panels are simulated in the ANSYS software. There are three methods for distributing uniaxially aligned reinforcements. The material properties of the carbon nanotubes uniformly distributed and functionally graded over the thickness of the shell structure are estimated using an extended rule of mixture micromechanical model that incorporates certain useful characteristics. To demonstrate the effectiveness and applicability of the proposed finite element approach, deflection data are presented. The analysis of the shell structure's bending includes an investigation of the impact of CNT volume fraction, boundary condition, lengthto-thickness ratio, and other geometrical factors

Influence of Plant Additives on Antimicrobial Properties of Glass-Fabric-Reinforced Epoxy Composites Used in Railway Transport.

The aim of this research was to explore the innovative use of natural additives, containing phytochemicals with proven antimicrobial effects, in the production of epoxy-glass composites. This study was based on information regarding the antimicrobial effects of phytochemicals present in Cistus incanus, Zingiber officinale, and Armoracia rusticana. The additives were subjected to a gas chromatography (GC) analysis to determine their composition, and, subsequently, they were used to prepare resin mixtures and to produce epoxy-glass composites. Samples of the modified materials were tested against E. coli, S. aureus, and C. albicans. In addition, flammability and durability tests were also performed. It was found that the strongest biocidal properties were demonstrated by the material with the addition of cistus, which caused a reduction of microorganisms by 2.13 log units (S. aureus), 1.51 log units (E. coli), and 0.81 log units (C. albicans). The same material also achieved the most favorable results of strength tests, with the values of flexural strength and tensile strength reaching 390 MPa and 280 MPa, respectively. Public transport is a place particularly exposed to various types of pathogens. Currently, there are no solutions on the railway market that involve the use of composites modified in this respect.

Free Vibration of Carbon Nanotube Reinforced Functionally Graded Shells

The main objective of this research is to investigate the vibration patterns of cylindrical panels composed of epoxy composites containing functionally graded Multiwall Carbon Nanotube (FG MWCNT). The research specifically addresses the issue of resonance failure, which is common in lightweight polymer composite structures that are subjected to dynamic forces. Curved components used in aircraft, automobiles, and marine vehicles, i.e. curved panels, conical shells, open shells and circular cylindrical shells, are particularly susceptible to this type of failure. The ANSYS software was used to consider three different types of uniaxial reinforcement distribution for modelling cylindrical panels made of FG-MWCNT epoxy composites. The extended rule of mixture of a micromechanical model is employed to determine the distribution of carbon nanotubes transversely the thickness of the structure, utilizing effective parameters. The research examines the impact of various geometrical considerations, such as the volume fraction of carbon nanotubes (CNTs),length to thickness ratio and boundary conditions on the analysis of vibration of the shell structure. The outcomes obtained from the suggested Finite Element Method (FEM) are obtainable to validate the performance and usefulness of the model.

Improved interfacial properties of carbon fiber reinforced epoxy resin composite by in‐situ self‐assembled mental‐phenolic networks

AbstractThe chemical modification of carbon fiber surface often uses toxic reagents and harsh reaction conditions, while the preparation process of metal‐phenol networks (MPNs) is simple, rapid, non‐toxic and harmless, which provides a direction for alleviating environmental problems. In this study, tannic acid (TA) was coordinated with Fe3+ to form MPNs, which was coated on the surface of carbon fibers through π‐π interaction. The results indicated that oxygen functionalities on the surface of the MPN coating can facilitate better adhesion between the carbon fiber and the epoxy resin, when the molar ratio of TA to Fe3+ is 1:3 and the pH is 4, the interlaminar shear strength (ILSS) performance of the composite material reaches its optimal level. In addition, a green and non‐destructive method is provided for the surface modification of carbon fiber, which can effectively optimize the interfacial properties of carbon fiber reinforced polymer (CFRP) composites.

Electrical and dynamic mechanical analysis of kenaf fiber reinforced epoxy composites hybridized with acacia concinna powder

The objective of this work is to create and analyze composites made of kenaf fibers and epoxy polymer, which are strengthened by the addition of Acacia concinna pod (ACP) powder. These composites are intended for use in electrical insulation applications. The study investigated the impact of alkali treatment using a 6% NaOH solution on kenaf fiber. The effects were analyzed in relation to the dielectric and dynamic mechanical properties, while also considering the addition of different quantities of ACP powder (0%, 4%, and 8%). The composites were produced using the hand layup method, and the dielectric constant, dissipation factor, storage modulus, loss modulus, and damping factor were assessed. The study demonstrated that NaOH-treated kenaf fiber composites displayed considerably lower dielectric constant values than untreated composites, due to increased fiber crystallinity and decreased moisture absorption. Dynamic Mechanical Analysis (DMA) found that untreated composites had greater storage modulus and glass transition temperature (Tg) due to reduced segmental motion at the fiber-matrix interface. SEM research indicated better fiber-matrix bonding in treated composites, with decreased voids and robust interlocking, notably in those containing 4% Acacia concinna (ACP) filler. These findings show that NaOH treatment substantially enhances the performance of hybrid composites for electrical insulating applications.

Interlaminar fracture properties of UV and plasma‐treated glass fiber epoxy composites

AbstractDespite the low density and high specific strength properties, the fiber‐reinforced composites are characterized by a relatively low interlaminar fracture toughness and their ultimate properties are strongly affected by the fiber matrix adhesion. This study aims to investigate the influence of fiber surface treatments, such as UV and atmospheric plasma, and of the interfacial shear strength, on the flexural properties and Mode I interlaminar fracture toughness of glass fiber epoxy composites. The vacuum‐assisted resin infusion technique is used for the composite fabrication. Scanning Electron Microscopy analysis is used to observe and to explain the changes in the morphology of the fibers after surface treatment. Remarkably, the results showed an overall reduction in the mechanical properties. The interfacial shear strength values of the UV and plasma‐treated samples were reduced by 34.9% and 49.5% respectively. The flexural strength was reduced by 7.9% and 5.9% respectively. The Mode I fracture toughness values for the UV and plasma‐treated samples were also reduced by 49.8% and 62.2% respectively.Highlights UV and plasma treatments were performed on glass fibers to improve performance. Push‐out tests were carried out to evaluate fiber/matrix adhesion. An aerospace grade epoxy resin curing in thermal press‐clave was used. Mechanical tests related Interfacial Shear Strength to composites performance.

Hierarchical Interfacial Construction by Grafting Cellulose Nanocrystals onto Carbon Fiber for Improving the Mechanical Performance of Epoxy Composites.

Carbon fiber-reinforced composites have been widely used in the aerospace industry because of their superior comprehensive performance, including high strength, low density, fatigue resistance, long service life, etc. The interface between the fiber reinforcement and the matrix is one of the key factors that determines the performance of the composites. The construction of covalent bonding connections between the components has proven to be an effective strategy for improving the interfacial bonding strength but always reduces the toughness. In this work, dual silane coupling agents are applied to covalently connect cellulose nanocrystals (CNCs) onto carbon fibers, constructing hierarchical interfacial connections between the fibers and the epoxy matrix and significantly improving the interfacial bonding strength. As a result, the tensile strength of the epoxy composites increased from 519 MPa to nearly 900 MPa, which provides a potential approach for significantly improving the mechanical performance of composites.

Fire retardancy of epoxy composites: A comparative investigation on the influence of porous structure and transition metal of metal-organic framework

Metal-organic frameworks (MOFs) are crystalline porous materials constructed by metal nodes and organic linkers. A series of key features such as high surface area, catalytic performance provide a platform for preparing MOF-based fire retardants (FRs). However, understanding the role of the porous structure and catalytic metal species remains a key issue towards the fire retardant mechanism of MOFs. This work systematically studied the difference between the performance of a zirconium based MOF(UiO-66), its derived porous zirconium oxide (U-ZrO2), and commercial ZrO2 (C-ZrO2), in imparting fire retardancy, suppressing smoke and charring property towards epoxy. With the presence of 3 wt% porous U-ZrO2, EP/3U-ZrO2 sample showed better performance in suppressing heat (10 % reduction) and toxic carbon monoxide (14 % reduction) than that of EP/3C-ZrO2 due to the “tortuous path” effect and formation of a compact char. Moreover, a greater number of exposed catalytic sites on MOF compared with thermally treated metal oxide significantly reduced total smoke production (TSP) of the EP/MOF sample by 38 %. Catalytic carbonization attributed to the great number of metal sites on MOF is crucial in providing compact char residue, thereby suppressing smoke for EP. In perspective, this work opens a window for understanding the fire retardant mechanism of MOF-based FR towards polymers.

Mechanical properties investigation of hybrid TI3C2TX MXene and carbon nanotube reinforced glass fiber epoxy composites

Mechanical properties investigation of hybrid TI3C2TX MXene and carbon nanotube reinforced glass fiber epoxy composites

Investigation of the Mechanical Properties of Hybrid E-Glass and Mohair Fiber Reinforced Epoxy Composites

Natural fiber composites have significant potential to replace traditional materials used in industries due to their excellent tensile strength, stiffness, low specific weight, and superior thermal and insulating properties. Mohair fiber, also known as the Noble fiber and the Diamond fiber, is obtained from the Angora goat, an animal of Tibetan origin. Renowned for its brilliant luster and resilience, Mohair is a symbol of luxury and exclusivity. The primary objective of this study is to manufacture and test a new natural fiber composite that could potentially outperform existing materials in real-world applications. Specifically, the study aims to investigate the mechanical properties of this composite. Mohair has previously been identified as a fiber many times stronger than a strand of steel of similar dimensions. Incorporating these highly desirable properties of Mohair into an epoxy matrix is one of the novel aspects of this research. The testing procedure begins with the preparation of ASTM molds, concurrent treatment of the fibers, and the preparation of the binding material. Specimens are created both with and without the addition of electrical glass (E- glass) fibers. The next phase is curing, during which the epoxy is allowed to solidify, forming strong bonds. Once developed and cured, the composites are removed from their molds and undergo post-processing and finishing techniques. This study aims to understand the tensile and flexural characteristics of natural fiber composites reinforced with epoxy. Three fiber orientations—uniaxial, biaxial, and criss-cross—are employed to assess the changes in the mechanical properties of the composites. The results indicate that adding E-glass fibers in alternating layers of the composite significantly enhances both tensile and flexural strength. Statistically, the addition of the biaxial arrangement of fibers with E-glass fibers results in an 18.47% improvement in ultimate tensile strength, while the maximum flexural strength increases by 49.90%. Furthermore, the topography of the cracked surface is examined using field emission scanning electron microscopy, and the breaking of the fibers in all three directions is studied.