Properties Of Epoxy Composites Research Articles

Mechanical Properties of Epoxy Composites Reinforced Using a Carbon Fiber Film Type Coated with Carboxyl Graphene via an Economical Electrophoretic Deposition Technique

Mechanical Properties of Epoxy Composites Reinforced Using a Carbon Fiber Film Type Coated with Carboxyl Graphene via an Economical Electrophoretic Deposition Technique

Three-dimensional interconnected graphene architecture reinforced epoxy composite with superior mechanical and tribological properties

The tribological performances reinforcement is limited by insufficient dispersion and random orientation of nanofillers in composites. In light of above difficulties, a three-dimensional (3D) interconnected graphene architecture (3DGA) was designed, in which the reinforcement is pre-formed in three dimensions. In the 3DGA reinforced epoxy composite (3DGA/EP) fabricated by resin transfer molding combined with in-situ ultrasonic method, 3DGA assembling from graphene sheets was in good dispersion and distribution state, which resulted in exceptional thermal stability, mechanical and tribological properties for epoxy composites. Compared with graphene oxide (GO)/EP composites in direct solution blending, glass transition temperature and tensile strength of the 3DGA/EP composites increased by 27.1 °C and 41.1 %, and wear rate decreased by 38.1 %, respectively. In this work, 3DGA was utilized as the ordered reinforcement of composites instead of two-dimensional graphene sheets, providing a promising strategy to achieve high-performance polymer-based composites with superior mechanical and tribological properties.

Codeposition of Gallic Acid and Polyethylene Imine on Carbon Fiber Surfaces to Enhance Interfacial Properties of Epoxy Composites

Codeposition of Gallic Acid and Polyethylene Imine on Carbon Fiber Surfaces to Enhance Interfacial Properties of Epoxy Composites

Mechanical and tribological properties of epoxy composites reinforced with food-waste fillers

One of the assumptions of the zero-waste economy is to reduce the amount of industrial waste produced, process it, and recover it without burning or burying it. Citrus peels are among the food wastes that are difficult to recycle. Due to the long time of decomposition and the waxes and fats in their structure, the shells rarely end up in composters and, consequently, are not included in natural fertilisers. The assumptions fit into the research described in the article.The authors investigated the possibility of using ground peels of citrus fruits: grapefruit, key lime, lemon and orange as fillers in composite materials in which the role of the matrix was played by epoxy resin. Composite materials with 2.5, 5 and 10% filler content were prepared. The materials were tested using the tensile, hardness, and abrasive tests using the pin-on-disc method.The research was to answer whether adding citrus waste can change the physicochemical properties of composite materials based on epoxy resin and native resin. Particular attention was paid to the properties that are important from the point of view of engineering applications: mechanical properties and tribological properties.In the face of challenges related to the growing amount of waste from the food industry, joint materials engineering tries to answer whether this waste can be used in the production of composite materials. In several publications from recent years, it has been postulated that used food industry products can be used as fillers for composite materials, as they can, on the one hand, improve specific physicochemical properties of new materials and manage food waste.The tests proved that composite materials with grapefruit and key lime as a filler were characterized by the best tribological properties, mechanical properties, and hardness, which were unchanged or better than the epoxy resin used as a matrix.

Influence of Layering Pattern, Fibre Architecture, and Alkalization on Physical, Mechanical, and Morphological Behaviour of Banana Fibre Epoxy Composites

In the current investigation, the mechanical properties of epoxy composites reinforced with banana pseudostem fibres, specifically focusing on tensile and impact behaviour, are investigated. The manufacturing process employed the meticulous hand-lay-up technique to fabricate six distinct samples. These samples included various combinations of short and woven banana fibres, treated and untreated, as well as a hybrid configuration involving layers of woven and short fibres. A fixed weight ratio of 60% fibres to 40% epoxy matrix was maintained for consistency. To ensure optimal material integrity, a careful application of resin and hardener in a 10 : 1 weight ratio was layered, with each addition of fibre followed by thorough rolling to eliminate any potential bubbles. The density and void fraction of the resulting composites were meticulously assessed to gauge the influence of this layering approach. Additionally, an X-ray diffraction (XRD) analysis was conducted to ascertain the impact of the chemical treatment on the cellulose content of the fibres. Our findings revealed that the tensile and impact properties were notably superior in the woven fibre composites. In particular, the chemically treated woven banana fibre epoxy composite displayed impressive values of 64.95 MPa for tensile strength and 24.37 KJ/m2 for impact strength. To gain deeper insights into the structure-property relationship, test specimens were analyzed using scanning electron micrographs. Lastly, comparative analysis by mapping the tensile properties from our present work with those from existing studies was carried out.

In Situ-Generated Heat-Resistant Hydrogen-Bonded Organic Framework for Remarkably Improving Both Flame Retardancy and Mechanical Properties of Epoxy Composites.

In this study, the heat-resistant hydrogen-bonded organic framework (HOF) material HOF-FJU-1 was synthesized via in situ generation and then used as flame retardants (FRs) to improve the flame retardancy of epoxy resin (EP). HOF-FJU-1 can maintain high crystallinity at 450 °C and thus function as a flame retardant in EP. The study found that HOF-FJU-1 facilitates the improvement of char formation in EP, thus inhibiting heat transfer and smoke release during combustion. For EP/HOF-FJU-1 composites, the in situ-generated HOF-FJU-1 can remarkably improve both the mechanical properties and the flame retardancy of EP. Furthermore, the in situ-generated HOF-FJU-1 has better fire safety than the ex situ-generated HOF-FJU-1 at the same filling content. Thermal degradation products and flame retardation mechanisms in the gas and condensed phases were further investigated. This work demonstrates that the in situ-generated HOF-FJU-1 is promising to be an excellent flame-retardant candidate.

Enhancement of thermal and mechanical properties of polymer composite using a novel milled bamboo filler

AbstractThis work presents the thermal and mechanical characterization of epoxy composites reinforced with different fillers developed by modifying thermo‐mechanically extracted bamboo micron fibers. The modification of bamboo fibers was done by adding carbon nanoparticles to their surface and also by making powdered fillers using the process of ball milling. A decrease in water absorption in case of surface coated bamboo fibers was observed. The glass transition behavior was enhanced for composites filled with milled bamboo fillers as compared to neat epoxy. Better mechanical properties were observed for composites reinforced with milled bamboo fillers compared to that of composites filled with bamboo fibers. The highest tensile strength (90.258 MPa) was observed for composites reinforced with 5 wt% of milled bamboo fillers depicting an increase of 93.01% compared to that of neat epoxy (46.762 MPa).Highlights Bamboo fibers were modified with a sizing agent and carbon nanoparticles. A novel “milled bamboo filler” was produced and incorporated in composites. Thermal properties of epoxy composite were enhanced by the novel filler. Tensile strength of the composite was significantly enhanced. The novel filler has the future scope of application in various composite products.

Dielectric Properties of Epoxy Composites Based on Ferroelectrics and MWCNTs in THz Frequency Range

Dielectric Properties of Epoxy Composites Based on Ferroelectrics and MWCNTs in THz Frequency Range

Impact of GNP content on cure behaviors and diverse properties of epoxy composites modified with graphene nanoplatelets: A comprehensive study

Nanocomposites modified with graphene nanoplatelet (GNP) have garnered significant attention and widespread application across various domains due to their substantial property enhancements. Nevertheless, excessive GNP incorporation not only leads to agglomeration within the polymer matrix but also degrades the base polymer's performance. Consequently, an investigation into the impact of GNP content on nanocomposite performance holds considerable significance. This study involves the dispersion of GNP with varying weight percentages into epoxy resin (EP) via ultrasonic dispersion to synthesize nanocomposites. The isothermal viscose-time properties were investigated to clarify the effect of the GNP on the curing speed and to suggest a suitable operating time for industrial production. Differential scanning calorimetry (DSC) was employed to investigate the curing kinetics so as to calculate the kinetic parameters and guide the curing process in practical industrial applications. In addition, mechanical properties and microstructure morphologies were analyzed by the direct tensile tests and scanning electron microscope (SEM) tests. Results showed that the addition of GNP in appropriate amounts is effective in promoting the curing reaction and improving the mechanical behavior. Specifically, GNP content was positively correlated with the increase of viscosity during the curing of the system. The EP@GNP-2 blend with 2 wt% GNP had the most significant effect on reducing the apparent activation energy, indicating that too much GNP may have an inhibitory effect on the curing reaction. The curing process parameters, including the gelling temperature (Tgel), curing temperature (Tcure) and post-treatment temperature (Ttreat) were calculated through the T-β extrapolation method. The elastic modulus of EP@GNP-1, EP@GNP-2 and EP@GNP-3 specimens increased by about 5%, 18% and 25%, respectively. However, the elongation at break showed a trend of increasing and then decreasing with the increase of GNP content. SEM tests show that excessive GNP content will attribute to the formation of a long barrier-like structure in the epoxy matrix to block the cross-linking of epoxy molecules on both sides, and the GNP agglomerates become stress concentration points and aggravate the brittleness of the nanocomposite. Furthermore, although a clear negative correlation between GNP content and thermal stability was revealed, the incorporation of GNP significantly enhances electrical conductivity. The results suggest that a reasonable GNP content is necessary, and a GNP content of 2 wt% is a recommended value for improving mechanics and curing efficiency.

A review on functionalization methods of graphene oxide for enhancement in mechanical properties of epoxy composites

In recent years the use of Graphene Oxide (GO) in composite materials is growing in engineering applications. However, the major drawback of adding Graphene Oxide (GO) inhibits the bonding between the matrix and the reinforcement which reduces the load transfer. Due to this reason, there is a need for functionalization of Graphene Oxide. Graphene oxide is a highly reactive grapheme derivative having nucleophiles. In this study different types of covalent and non-covalent bonding functionalization methods of GO for dispersion in epoxy composites are discussed with their preparation and characterization. A comparative analysis of GO gives understanding of methods of functionalization affect with respect to mechanical and chemical properties. This study gives variety of processes involved and its influence on mechanical and chemical behaviour of the epoxy composites. Among all the methods mentioned for functionalization of GO, Amino-siloxane (APS), Polyethyleneimine (PEI) and triton shows effective results in improvement of mechanical properties.

Impact of Mendong fiber–epoxy composite interface properties on electric field frequency exposure

AbstractThis research investigates the effects of the frequency of the external electric field during the curing process on the interfacial properties of epoxy composites reinforced by Mendong fiber. Epoxy was used as a matrix with cycloaliphatic amine as a curing agent. The AC electric field by frequencies of 1, 2, and 3 kHz and strength of 750 V/cm were applied during the curing process. The functional groups, structure, interface properties, and morphology of treated epoxy were observed using Fourier‐transform infrared, x‐ray diffraction, scanning electron microscope, and pull‐out test, respectively. The result indicates that after treatment with an electric field of 1 kHz, new peaks were observed in the epoxy diffractogram at the angle of 6.2° and 12.3°, change in morphology, the wettability properties of epoxy were increased and interface shear strength was improved. Increasing the frequency of electric fields results in more damage to the interface and subsequently reduces the shear strength at the interface.Highlights Interface properties of the composite after curing in an electric field characterized. Exposure to electric field frequency during curing changed epoxy properties. Shear strength of Mendong fiber/epoxy varied post‐exposure to the electric field.

Tailoring the Magnetic and Electrical Properties of Epoxy Composites Containing Olive-Derived Biochar through Iron Modification.

The combination of conductive carbon together with magnetic particles is a consolidated strategy to produce cutting-edge fillers for the production of polymer composites able to shield against microwave radiation. In this work, we developed and characterized an iron-tailored biochar obtained from the pyrolysis of olive pruning which was added as filler for the preparation of epoxy composites. The biochar-based composites were obtained by keeping the filler concentration at 10 and 40 wt.%. An extensive characterization was carried out in order to assess the electrical and magnetic properties of the composites containing biochar and iron-tailored biochar. The highest DC electrical conductivity of 59 mS/m was observed in the 40 wt.% iron-tailored biochar-loaded composite, while the reduction of the filler loading led to a drastic reduction in conductivity: 60 μS/m in the 10 wt.%-loaded composite. Ferromagnetic behavior of composites containing iron-tailored biochar is visible in the emerging hysteretic behavior, with a magnetic signal increasing with the filler concentration. Finally, both the complex permittivity (ε') and the AC conductivity (σ) are enhanced by increasing the BC filler amount in the matrix, regardless of the presence of iron.

Enhanced Thermal Conductivity and Dielectric Properties of Epoxy Composites with Fluorinated Graphene Nanofillers.

The demand for high-performance dielectrics has increased due to the rapid development of modern electric power and electronic technology. Composite dielectrics, which can overcome the limitations of traditional single polymers in thermal conductivity, dielectric properties and mechanical performance, have received considerable attention. In this study, we report a multifunctional nanocomposite material fabricated by blending fluorinated graphene (F-graphene) with epoxy resin. The F-graphene/epoxy composite exhibited a high thermal conductivity of 0.3304 W·m-1·K-1 at a low filler loading of 1.0 wt.%, which was 67.63% higher than that of pure epoxy. The composite dielectric also showed high breakdown strength (78.60 kV/mm), high dielectric constant (8.23), low dielectric loss (<0.015) and low AC conductivity (<10-11 S·m-1). Moreover, the composite demonstrated high thermal stability and strong mechanical strength. It is believed that the F-graphene/epoxy composite has outstanding performance in various aspects and can enable the development and manufacturing of advanced electric power and electronic equipment devices.

Effects of plasma treatment on surface insulation properties of epoxy composites

The surface of epoxy composite material working in DC electric field for a long time is easy to accumulate charge and cause flashover, which seriously reduces its insulation level and poses a threat to the safe operation of electrical equipment. In this study, SiO x films were deposited on the surface of nano-SiO2/ER nanoparticles by atmospheric pressure dielectric barrier discharge plasma vapor deposition technology using ethyl nor-silicate as a precursor. The effects of different deposition time on the deposition effect and the pressure level of the film surface were studied. Scanning electron microscope and atomic force microscope were used to characterize the surface morphology of the material, and the flashover voltage before and after deposition was measured. The results show that SiO x films of different thicknesses can be formed on the surface of the material at different times of plasma deposition. After extending the deposition time of the film, the film becomes more uniform and dense, the surface roughness of the material decreases continuously, and the electrical conductivity and flashover voltage along the surface increases continuously. After 10 min plasma treatment, the conductivity increased from 1.78×10−16 S to 2.3×10−13 S, while the flashover voltage along the surface increased from 19.29 kV to 22.66 kV, an increase of about 17.5%.

Effect of Self-Healing by Dicyclopentadiene Microcapsules on Tensile and Fatigue Properties of Epoxy Composites.

Microcapsules of urea-formaldehyde (UF) containing dicyclopentadiene (DCPD) were synthesized by the in situ polymerization technique for self-healing of epoxy. The dispersion of microcapsules in the epoxy matrix was achieved using ultrasonication. Composites of epoxy, having 0.5, 1.0, 1.5, and 2.0 wt.% of microcapsules capable of self-healing, were prepared. The shape and size of the microcapsules were determined by field emission electron microscopy. Spherical capsules of DCPD, with an average diameter of 172 nm, were obtained. Investigation of tensile properties indicated a decrease in the tensile modulus with an increase in wt.% of microcapsules. There was a reduction of 22%, 27%, 39%, and 30% in the elastic modulus of composites for 0.5, 1.0, 1.5, and 2.0 wt.% of microcapsules, respectively. Tensile strength was found to increase with an increase in wt.% of microcapsules. The tensile strength of the composites increased by 33%, 20%, 8%, and 21% for 0.5, 1.0, 1.5, and 2.0 wt.% of microcapsules, respectively, in comparison with that of neat epoxy. The fatigue life of composites was investigated by conducting uniaxial tension-tension fatigue tests at constant stress amplitudes of 20, 25, 30, and 35 MPa, at a constant stress ratio (R = 0.1) and a frequency of 3 Hz. The fatigue life of composites increased with an increase in wt.% of microcapsules in comparison with that of neat epoxy. It was found that the fatigue life of the composites decreased with 1.5 and 2.0 wt.% of microcapsules in comparison with composites with 0.5 and 1.0 wt.% of microcapsules. The fracture surfaces of the tested samples were examined with the help of scanning electron microscopy (SEM) to understand the various mechanisms responsible for the change in modulus, strength, failure strain, and fatigue life of composites.

Effects of graphene surface morphology on damping properties of epoxy composites

In nature, a rougher surface is usually accompanied by a higher friction coefficient, providing greater friction with the objects in contact. The higher surface roughness of nanofillers dispersed in the matrix might improve the energy dissipation capacity of composites. For a better understanding of the mechanism of different damping enhancement capabilities of graphene, comparative studies on composites reinforced with two types of graphene are carried out to evaluate the factors such as surface roughness, friction, dispersion, and the specific surface area. Reduced graphene oxide (rGO) and graphene oxide (GO) are selected as reinforcement, where the composites are fabricated and the damping properties are tested. The results indicate that adding rGO/GO can significantly increase the damping ratios of composites. The damping ratios of composites reinforced with 0.3% weight ratio rGO and GO increase to 3.01% and 4.13% from 2.27% for pure resin, respectively, which indicates that GO has superior damping enhancing capability. The mechanism of graphene surface wrinkles for increasing the friction force induced higher damping capacity is analyzed on the microscopic scale. The influencing factors studied in this paper shed light on the subsequent selection of graphene with high damping enhancement capabilities.

Dielectric Properties of Epoxy Composites Containing Silver Nanoparticle and Carbon Nanotube over the X-Band Frequency

Materials with high dielectric properties have become interested due to their important applications, mainly in electronics and energy storage. This study assesses the dielectric properties of epoxy composites containing silver nanoparticles (AgNPs) and carbon nanotube (CNT) composite materials. These samples' permittivity and reflective properties were measured using Vector Network Analyser (VNA) within the X-band frequency (8.2 – 12.4 GHz). Samples were prepared at various loading (0.1-5 wt.%), with various thickness of (0.5, 1.0, 1.5 and 2.0 mm). Regardless of the fillers loading and sample thickness, it was found that the values of real permittivity, er', remain constant along the frequency range. At the same sample thickness, it was found that the values of both er' and er'' increase as loading increases, indicating the function of AgNPs and CNT in enhancing the dielectric and electrical conductivity properties of epoxy composites, respectively. The highest value of er' is recorded as 5 F/m (at f = 8.2 GHz), measured at 5 wt.% loadings and 0.5 mm sample thickness. Measurement on S11 parameters at f = 8.2 GHz indicated that the SER values are between 9 dB and 15 dB, with no obvious pattern observed, regardless of the fillers loading and sample thickness. This study highlights the dielectric properties improvement of epoxy composites by incorporating dual fillers.

Impedance and Dielectric Characterization of Epoxy Composites Containing Carbon Black and Carbon Nanotubes

Research in improving dielectric materials is rapidly becoming more intense as there are higher demands for novel materials with the ability to store charges. In this work, impedance characterisation and dielectric properties of epoxy composites containing Carbon Black (CB) and a mixture of CB and Carbon Nanotube (CNT), kept at 1:1 wt.% is conducted. For both cases, the total number of fillers are varied from 0.5 wt.% to 6 wt.%. At 20 Hz, the values of dielectric composites, k was recorded to be 2050 for 6 wt.% CB, compared to k = 600, for composites containing dual filler (3 wt.% CB + 3 wt.% CNT). Further analysis revealed that the 6 wt.% sample (CB + CNT) exhibited higher ac conductivity at lower frequency, compared to sample containing only 6 wt.% CB. This could be due to the reason that CNT has more conductivity effects while CB has more storage or capacitive effects. Nyquist plot of impedance for both fillers also revealed the formation of semi-circular shapes for 5 wt.% and 6 wt.%; for both CB and CB + CNT fillers. However, formation of smaller semi-circular shapes is observed for CB + CNT, compared to CB only, indicating formation of conductive network in dual filler composites. This study highlights the potential of CB in enhancing mainly the dielectric properties of epoxy composites.

Research on thermal conductivity and electrical insulation properties of epoxy composites with fluorescent grafted zero-dimensional Al2O3

Research on thermal conductivity and electrical insulation properties of epoxy composites with fluorescent grafted zero-dimensional Al2O3

Low electric field induction in BaTiO3-epoxy nanocomposites

Epoxy is widely used material, but epoxy has limitations in terms of brittleness in failure, and thus researchers explore toughening and strengthening options such as adding a second phase or using electromagnetic fields to tailor toughness and strength, on demand and nearly instantaneously. Such approach falls into the category of active toughening but has not been extensively investigated. In this research, Si-BaTiO3 nanoparticles were used to modify the electro-mechanical properties of a high-performance aerospace-grade epoxy so as to study its response to electric fields, specifically low field strengths. To promote uniform dispersion and distribution, the Si-BaTiO3 nanoparticles were functionalised with silane coupling agents and mixed in the epoxy Araldite LY1564 at different content loads (1, 5, 10 wt%), which was then associated with its curing agent Aradur 3487. Real-time measurements were conducted using Raman spectroscopy while applying electric fields to the nanocomposite specimens. The Raman data showed a consistent trend of increasing intensity and peak broadening under the increasing electric field strength and Si-BaTiO3 contents. This was attributed to the BaTiO3 particles’ dipolar displacement in the high-content nanocomposites (i.e., 5 wt% and 10 wt%). The study offers valuable insights on how electric field stimulation can actively enhance the mechanical properties in epoxy composites, specifically in relatively low fields and thin, high-aspect-ratio composite layers which would require in-situ mechanical testing equipped with electric field application, an ongoing investigation of the current research.