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The usage of jute/cotton natural composites has surged in almost all fields of engineering due to their advantage of possessing high strength to weight ratio and biodegradability. This paper deals with the fabrication and investigation of mechanical properties of jute/cotton fiber reinforced epoxy composite which is relatively a hybrid composite. In this study, the composite is fabricated by a hand layup process followed by compression molding method with varying the number of layers of composite laminates also with different cutting angles. The composites are prepared with four different proportions of jute/cotton fibers. Various mechanical tests are conducted and the result shows that the 14-layer jute/cotton composite has optimum properties achieved and also observed that 90° has better properties than the others cutting angles. Statistical analysis of composites was done by ANOVA-table; based on mean effective plots, the optimum levels of parameters have been identified, and significant contribution of parameters is determined by analysis of variance Also, failure morphology analysis is done using a scanning electron microscope (SEM) through which the internal structures of the tested specimen are analyzed. [ABSTRACT FROM AUTHOR]

Laser powder bed fusion (L-PBF) additive manufacturing technology can print multi-material parts with multiple functions/properties, and has great potential for working in harsh application environments. However, the metal blank formed by sintering metal powder material with binder added through L-PBF has an obvious porous structure and insufficient mechanical properties, and few studies have been conducted studying this. In this paper, epoxy resin was used to impregnate the blank of porous metal parts formed by L-PBF with iron-based powder material at a certain temperature, and a cross-linked curing reaction was carried out with three kinds of phenolic resin in different proportions under the action of a curing agent, so as to fill the pores and achieve the desired mechanical properties. The characteristic peaks of each group of epoxy resin were characterized using Fourier transform infrared spectroscopy (FT-IR) and H-nuclear magnetic resonance (1H-NMR) spectrums. The microstructure, decomposition temperature, and residue of four epoxy resin dispersion systems were analyzed with a scanning electron microscope (SEM), a thermal gravimetric analyzer (TGA), and derivative thermogravimetry (DTG). The results show that the density of the porous metal parts was obviously improved, the heat resistance temperature of the parts could reach 350 °C, and the tensile strength of the sample after EP2-1 impregnation was increased by 4–6 times after curing at 160 °C for 6 h. Therefore, the use of an epoxy resin dispersion system can increase the porosity of L-PBF porous metal parts, but can also significantly improve their mechanical properties, which can help them to meet the requirements of applications as model materials, biological materials, and functional materials to provide a feasible solution. [ABSTRACT FROM AUTHOR]

This research paper presents a comparative experimental study on the impact of zinc oxide and zirconium dioxide nanomaterials on the chemical, mechanical, and crystalline properties of epoxy resin (diglycidyl ether of bisphenol-A). Nanomaterials were incorporated into the epoxy resin at three different concentrations (4%, 6%, and 8%) by weight. Results indicated enhanced properties of the epoxy resin, including tensile and compressive strengths, as well as improvements in chemical and crystalline characteristics, assessed through scanning electron microscope (SEM) and Fouriertransform infrared spectroscopy (FTIR). Notably, zirconium dioxide exhibited superior performance across all properties, enhancing tensile and compressive strengths by 67% and 50%, respectively. Zinc oxide, at the same concentrations, led to a 50% increase in tensile strength and a 40% increase in compressive strength. These outcomes were observed at the highest concentration (8%wt) of both nanomaterials and the pure epoxy resin. The presence of nanomaterials at this ratio promoted greater cohesion within the composite, as evidenced by SEM images of selected samples. SEM analysis highlighted the pivotal role of ZrO2 nanoparticles in improving epoxy integration, surface quality, crystallization, and imperfection removal, crucial factors for enhancing composite materials. FTIR analysis of the resin containing ZrO2 nanoparticles revealed shifts and alterations in peaks, indicating successful nanoparticle-epoxy interaction, resulting in notable structural changes. [ABSTRACT FROM AUTHOR]

The permeation of marine water can lead to severe degradation of the protective properties of polymer composite coatings. At present, experimental studies on the anticorrosive and mechanical properties of polymer composite coatings are relatively mature, but the impermeability and mechanical property changes of the coating during the permeation process are challenging tasks to be studied only by experiments. In this paper, molecular dynamics (MD) models of composite coatings consisting of pure epoxy resin (EP), graphene/epoxy resin (Gr/EP), and graphene oxide/epoxy resin (GO/EP) were constructed respectively. MD simulations were performed to reveal the impermeability and mechanical property changes of composite coatings from an atomic perspective. The results show that GO has strong interfacial interaction with EP and the best effect to enhance the impermeability and mechanical properties of epoxy coatings. NaCl solutions can damage the coating microstructure and occupy the Gr and GO surfaces, causing them to no longer have an enhancing effect. The study of GO/EP coatings with different permeation degrees shows that the mechanical properties of the coating decrease as the penetration degree increases. [ABSTRACT FROM AUTHOR]

Epoxy resin, a high-performance thermosetting polymer with good mechanical properties, has been widely used as a structural composite and adhesive agent for various industries. However, epoxy resins suffer from brittle characteristics owing to their highly cross-linked structure. Such a shortage has restricted their application. In this regard, adding a suitable filler to the epoxy resin has been intensively studied and employed as a feasible strategy to overcome this shortage. Different types of fillers, including those with size classified under nano-range, and those not in nano-range, can be used for this purpose. In particular, the uses of nanoparticles as fillers have attracted much attention due to their unique intrinsic properties and high interfacial area that enables effective interaction with the epoxy resin. This paper aims to provide a brief review of the current research associated with the uses of nano and non-nano fillers in reinforcing epoxy resin. Interestingly, by comparing the data collected from past published works, it was found that the amount of non-nano filler required to reinforce epoxy resin is about 10 to 100 times more than the amount needed when nanofillers were applied. In this paper, the properties of the epoxy resins (after being added with either nano or non-nano fillers), research gaps, and prospects of the research area are delineated. [ABSTRACT FROM AUTHOR]

In this paper, mechanical properties of the diglycidyl ether of bisphenol A epoxy resin (EP) reinforced with a 20% fiber glass (GF) with layered structure after high temperature aging are studied. Tensile and flexural stress–strain curves of the GF/EP composite after aging tests in the temperature range of 85–145 °C in air were measured. Tensile and flexural strength demonstrate gradual decrease with the increase in the aging temperature. The failure mechanism at the micro scale is studied by the scanning electron microscopy. A separation of the GFs and EP matrix and evident pullout of the GFs are observed. Degradation of the mechanical properties is explained by a cross-linking and chain scission of the initial molecular structure of the composite and decrease in the interfacial adhesion force between GFs and EP matrix caused by oxidation of the EP matrix and difference of the GF and EP coefficients of thermal expansion. [ABSTRACT FROM AUTHOR]

This article presents a review on the recent advances in the field of ternary diglycidyl ether of bisphenol A epoxy nanocomposites containing nanoparticles and other modifiers. Particular attention is paid to their mechanical and thermal properties. The properties of epoxy resins were improved by incorporating various single toughening agents, in solid or liquid states. This latter process often resulted in the improvement in some properties at the expense of others. The use of two appropriate modifiers for the preparation of hybrid composites, possibly will show a synergistic effect on the performance properties of the composites. Due to the huge amount of modifiers that were used, the present paper will focus mainly on largely employed nanoclays with modifiers in a liquid and solid state. The former modifier contributes to an increase in the flexibility of the matrix, while the latter modifier is intended to improve other properties of the polymer depending on its structure. Various studies which were carried out on hybrid epoxy nanocomposites confirmed the occurrence of a synergistic effect within the tested performance properties of the epoxy matrix. Nevertheless, there are still ongoing research works using other nanoparticles and other modifiers aiming at enhancing the mechanical and thermal properties of epoxy resins. Despite numerous studies carried out so far to assess the fracture toughness of epoxy hybrid nanocomposites, some problems still remain unresolved. Many research groups are dealing with many aspects of the subject, namely the choice of modifiers and preparation methods, while taking into account the protection of the environment and the use of components from natural resources. [ABSTRACT FROM AUTHOR]

Cyclotriphosphazenes, a variety of inorganic rings together with a curing ingredient, 4,4′-methylene dianiline (MDA), are mainly used to enhance the thermal conductivity and mechanical characteristics of epoxy resin (DGEBA). Three DGEBA@MDA, HGCP@MDA, and thermosets were produced, and their curing behaviors were investigated. Using a molecular dynamics (MD) approach, the impact of cyclotriphosphazene on the characteristics of DGEBA composites is thoroughly explored in this paper. Results indicated that the glass transition temperatures (Tg) of DGEBA containing HGCP had slightly decreased compared to DGEBA. With the addition of HGCP to DGEBA, epoxy resin (DGEBA@HGCP@MDA) has a high thermal conductivity of 0.215284 W/m·K, with an increase of 116.04% more than pure DGEBA (0.185524 W/m·K). Moreover, the DGEBA@HGCP@MDA composite has high mechanical strength with a specific Young's modulus of 5.4902 GPa. In order to forecast and analyze certain performances directly associated with the microstructure characteristics of the various cross-linked resin systems and their composite materials, an MD simulation approach will be quite valuable. [ABSTRACT FROM AUTHOR]

This paper presents the development of novel hybrid composites in the presence of filler particles and manufactured using a proposed new fabrication technique. The hybrid composites were fabricated using a basalt and E-glass woven fabric–reinforced epoxy resin matrix combined with graphite powder nanoparticles. Six sets of samples were fabricated using the vacuum-assisted free lamination compression molding technique. After the fabrication, wettability, mechanical properties (tensile, flexural and impact properties) and moisture properties were evaluated. Surface morphology and chemical composition of the composite samples were examined using a scanning electron microscope (SEM) and spectroscopy. The obtained results showed that the use of filler materials in hybrid composites improves the properties of hybrid composites. Basalt/E-glass hybrid composites with 10% graphite material exhibited superior mechanical properties over the other composites, with high-quality, improved adhesion and surface morphology. Thus, novel composites with the combination of exceptional properties may be integrated in the design of flexible electronics and microfluidics devices as a structural layer of the system. High flexibility and good surface tension of the designed composites makes them attractive for using the thermal imprint technique for microfluidics channel design. [ABSTRACT FROM AUTHOR]

The application of epoxy resins in high temperature and thermal protection fields is limited due to their low decomposition temperature and low carbon residual rate. In this paper, epoxy resin (EP)/quartz fiber (QF) ceramifiable composites were prepared using a prepreg-molding process. The thermal stability, phase change and mechanical properties after high-temperature static ablation and ceramization mechanism of EP/QF ceramifiable composites were investigated. The addition of glass frits and kaolinite ceramic filler dramatically increases the thermal stability of the composites, according to thermogravimetric (TG) studies. The composite has a maximum residual weight of 61.08%. The X-ray diffraction (XRD) results show that the mullite ceramic phase is generated, and a strong quartz diffraction peak appears at 1000 °C. The scanning electron microscope (SEM) and element distribution analyses reveal that the ceramic phase generated inside the material, when the temperature reaches 1000 °C, effectively fills the voids in composites. The composites have a bending strength of 175.37 MPa at room temperature and retain a maximum bending strength of 12.89 MPa after 1000 °C treatment. [ABSTRACT FROM AUTHOR]

Oil-well cement-based materials have inherent brittleness; therefore, they cannot be directly used to seal oil and gas wells for a long time. To improve the elasticity of oil-well cement-based composites, a flexible epoxy resin system was developed. The flexibility, TG, and SEM of the cured resin system were evaluated. At the same time, the resin was added to oil-well cement-based materials to improve its elasticity. The compressive strength and elastic modulus of resin cement stone were tested, and the microstructure was analyzed by XRD, TG, and SEM/EDS. The results showed that the structure of the cured resin is compact, the thermal decomposition temperature is 243.9 °C, and it can recover its original shape after compression. At the curing age of 28 days, the compressive strength of cement-based composites containing 30% resin decreased by 26.7%, while the elastic modulus significantly decreased by 63.2%, and the elasticity of cement-based composites was significantly improved. The formation of hydration products (e.g., calcium silicate hydrate, and calcium hydroxide) in the resin cement slurry is obviously lower than that of pure cement, which is the reason for the decrease in compressive strength. The flexible structure of polymer particles and polymer film formed by epoxy resin is distributed inside the cement stone, which significantly improves the elasticity of oil-well cement-based composites. The results of this paper are helpful for the design of elastic cement slurry systems. [ABSTRACT FROM AUTHOR]

The spread of 3D printing in many different fields has become eminent. This paper aims to improve the mechanical properties of parts printed by fused deposition modeling technique. Acrylonitrile butadiene styrene (ABS) specimens are printed with custom printing parameters. These parameters give a tensile strength that is 86% of the injection- molded ABS strength, and give one of the best recorded results for 100% infill printed ABS tensile specimens. Furthermore, a post filling technique has been studied. Specimens are printed with inner voids and different densities using slicing software. Void shape is precisely selected to conform to the filling process. High-strength, low-cost thermoset resin is injected through specimens to fill those voids. A tensile test has been performed after the full curing of the resin. A morphology analysis is done. Using this technique strength to printed weight ratio is improved by 151% and the cost is reduced by 51%. [ABSTRACT FROM AUTHOR]

When the thermoplastic composites reach the service limits during the service, the recovery and utilization are the key concerns. Meanwhile, the improvement of strength, toughness and durability of epoxy resin is the effective method to prolong the service life of materials and structures. In the present paper, three kinds of thermoplastic resins (polypropylene-PP, polyamide 6-PA6 and polyether-ether-ketone-PEEK) and composites (carbon fiber-PEEK, glass fiber-PA6 and glass fiber-PP) were adopted as the fillers to reinforce and toughen the epoxy resin (Ts). The mechanical, thermal and microscopic analysis were conducted to reveal the performance improvement mechanism of Ts. It can be found that adding thermoplastic resin and composite fillers at the low mass ratio of 0.5~1.0% brought about the maximum improvement of tensile strength (7~15%), flexural strength (7~15%) and shear strength (20~30%) of Ts resin. The improvement mechanism was because the addition of thermoplastic fillers can prolong the cracking path and delay the failure process through the load bearing of fiber, energy absorption of thermoplastic resin and superior interface bonding. In addition, the thermoplastic composite had better enhancement effect on the mechanical/thermal properties of Ts resin compared to thermoplastic resin. When the mass ratio was increased to 2.0~3.0%, the agglomeration and stress concentration of thermoplastic filler in Ts resin appeared, leading to the decrease of mechanical and thermal properties. The optimal addition ratios of thermoplastic resin were 0.5~1.0% (PEEK), 1.0~2.0% (PA6) and 0.5~1.0% (PP) to obtain the desirable property improvement. In contrast, the optimal mass ratios of three kinds of composite were determined to be 0.5~1.0%. Application prospect analysis indicated adding the thermoplastic resin and composite fillers to Ts resin can promote the recycling and reutilization of thermoplastic composites and improve the performance of Ts resin, which can be used as the resin matrix, interface adhesive and anti-corrosion coating. [ABSTRACT FROM AUTHOR]

Magnesium hydroxide is a promising green flame retardant, but the amount of added material affects the mechanical properties of the matrix. Therefore, finding a proper ratio of the inorganic and organic flame retardants is still challenging. In this paper, a novel inorganic curing agent containing Mg, P, and N was synthesized and used in epoxy resin. Besides the curing function, it also exhibited excellent flame-retardant properties. When the addition amount was 20 wt%, the peak heat release and peak smoke generation were reduced by 75.7 and 64.1%, respectively, while its flexural strength and flexural modulus were increased by 79.9 and 61.22%, respectively. Scanning electron microscopy and Raman spectroscopy were used to study the carbon residue after combustion systematically, and the flame-retardant mechanism was discussed. The phosphorus-nitrogen inorganic flame-retardant curing agent reduced fire hazards and showed excellent comprehensive performance, having broad application prospects in the field of flame-retardant epoxy resins. [ABSTRACT FROM AUTHOR]

The interfacial structure between the inorganic filler and epoxy resin matrix in epoxy resin (EP) composites has a great influence on the mechanical properties, thermal conductivity, and electrical properties. In this paper, two micro@nanostructured Al2O3 fillers and their epoxy resin composites were prepared, and their morphology, interfacial bond strength, mechanical properties, thermal conductivity, and electrical properties systematically tested and analyzed. The experimental results show that modification by a nano-Al2O3 coating on the surface of micro-Al2O3 can effectively improve the infiltration of Al2O3 filler and epoxy resin, reduce the interfacial defects caused by weak bonding of Al2O3 filler and epoxy resin, and thus synergistically improve the mechanical properties, thermal conductivity, and electrical properties of epoxy resin composites. The thermal conductivity was improved by 22.5% compared with 22.65% when using micro-Al2O3/EP, the tensile and flexural strength were improved by 36.67% and 20.82%, and the alternating-current breakdown strength was improved by 12.88%. In addition, thermally stimulated current experiments were carried out to study the electron transport properties of micro@nano-Al2O3 epoxy resin composites, revealing that filler nanomodification could improve the trap depth, suppress the carrier transport, and improve the dielectric properties of the composites. [ABSTRACT FROM AUTHOR]

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Aiming at the problems of insufficient flexural strength and low durability of cement concrete, this paper prepared concrete with different content of epoxy resin（0%, 3 wt%, 6 wt%, 9 wt%） by using epoxy resin as doping phase, and analyzed the influence of epoxy resin on the mechanical properties, micro appearance and durability of cement concrete. The results show that the doping of epoxy resin accelerates the hydration reaction, reduces the number of cracks and pores, and improves the density of concrete. The compressive strength and flexural strength both increased first and then decreased with the increase of resin doping. The compressive strength and flexural strength of the concrete with 6 wt% epoxy resin doping reached the maximum values of 43.8 and 7.9 Mpa respectively when cured for 28 d, which increased by 18.70% and 29.51% respectively compared with the concrete without resin doping. The chloride ion diffusion coefficient of concrete decreases first and then increases with the increase of resin doping amount. The chloride ion diffusion coefficient of concrete with 6 wt% epoxy resin doping content for 28 d is the lowest of 7.7×10-8 cm/s, and the chloride ion corrosion resistance is the best. When the number of freeze-thaw cycles reaches 80, the concrete with 6 wt% epoxy resin doping has the lowest mass loss rate of-0.13%, the highest relative dynamic elastic modulus of 94.86%, the lowest wear amount of 0.66 kg/m², and the wear amount reduction rate of 46.77%. It has excellent durability. [ABSTRACT FROM AUTHOR]

Thermoset-based polymer composites containing functional fillers are promising materials for a variety of applications, such as in the aerospace and medical fields. However, the resin viscosity is often unsuitably high and thus impedes a successful filler dispersion in the matrix. This challenge can be overcome by incorporating suitable low-viscosity modifiers into the prepolymer. While modifiers can aptly influence the prepolymer rheology, they can also affect the prepolymer curing behavior and the mechanical and thermal properties of the resulting matrix material. Therefore, this study investigates the effects that a commercial-grade low-viscosity additive (butyl glycidyl ether) has on a common epoxy polymer system (diglycidyl ether of bisphenol-A epoxy with a methylene dianiline curative). The weight percentage of the modifier inside the epoxy was varied from 0 to 20%. The rheological properties and cure kinetics of the resulting materials were investigated. The prepolymer viscosity decreased by 97% with 20 wt% modifier content at room temperature. Upon curing, 20 wt% modifier addition reduced the exothermic peak temperature by 12% and prolonged the time to reach the peak by 60%. For cured material samples, physical and thermo-mechanical properties were characterized. A moderate reduction in glass transition temperature and an increase in elastic modulus was observed with 20 wt% modifier content (in the order of 10%). Based on these findings, the selected material system is seen as an expedient base for material design due to the ease of processing and material availability. The present study thus provides guidance to researchers developing polymer composites requiring reduced prepolymer viscosity for successful functional filler addition. [ABSTRACT FROM AUTHOR]

Natural fibre-reinforced polymer composite (NFRPC) has been introduced as one of the solutions to overcome the ecological and environmental problems accompanying the widespread usage of polymeric materials in every facet of life. However, the organic nature of both natural fibres (NFs) and polymers increases their flammability behaviour, and this, in turn, limits their application. In this regard, this work concentrates on studying the effect of adding flame retardants (FR) to jute-reinforced epoxy composites (JRECs), either by treating the jute fabric with diammonium phosphate (DAP) or adding DAP powder to the epoxy resin matrix on the flame retardancy performance as well as the mechanical properties. The results showed that the effect of the incorporation method of DAP either to jute fabric or to resin matrix has a significant difference on the flammability test results at low concentrations; however, at higher concentrations, the flame retardancy performance is not affected by the technique of adding FR to the composite system. On the other hand, the mechanical properties are significantly affected by the method of incorporating FR to JRECs at all concentrations. Moreover, the results obtained from JRECs with FR systems were evaluated and compared with the literature by constructing selection charts that relate the flame retardancy level to mechanical properties. [ABSTRACT FROM AUTHOR]

This research aims to highlight the importance of diverse forms of graphitic carbon nitride (g-C3N4) as strengthening elements in epoxy composites. It explores the influence of three different forms of g-C3N4 and their concentrations on the mechanical properties of the epoxy composites. Various characterization techniques, such as scanning electron microscopy (SEM), dynamic light scattering (DLS), thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR), were utilized to comprehend the effects of g-C3N4 morphology and particle size on the physical and chemical characteristics of epoxy resin. Mechanical properties, such as tensile strength, strain, modulus, and fracture toughness, were determined for the composite samples. SEM analysis was performed to examine crack morphology in samples with different reinforcements. Findings indicate that optimal mechanical properties were achieved with a 0.5 wt% bulk g-C3N4 filler, enhancing tensile strength by 14%. SEM micrographs of fracture surfaces revealed a transition from brittle to rough morphology, suggesting increased toughness in the composites. While the TGA results showed no significant impact on degradation temperature, dynamic mechanical analysis demonstrated a 17% increase in glass transition temperature. Furthermore, the improvement in thermal breakdown up to 600 °C was attributed to reinforced covalent bonds between carbon and nitrogen, supported by FTIR results. [ABSTRACT FROM AUTHOR]

In recent years, research has focused heavily on the investigation of functionalized ammonium polyphosphate (APP) flame retardants to improve the fire safety of epoxy resins (EP). The reason for this is the dual nature of APP’s performance in fire protection of EP. This article provides a comprehensive overview of the advances in the use of functionalized APP flame retardants to improve the fire resistance of EP materials. It then presents the improvement of the modification of the functionalized APP flame retardants in terms of the hydrophobicity, compatibility and catalytic ability of the flame retardants, as well as the effects on the fire resistance, heat resistance, smoke reduction and mechanical properties of the EP composites. After the summary and comparison of the relevant studies, it is clear that the functionalized APP flame retardants can effectively improve the fire safety of EP composites and offset the adverse effects of APP in EP flame retardant applications. In addition, APP flame retardants can obtain various excellent functions through the use of materials with different properties, and the interaction between APP and materials can also lead to more efficient fire protection. However, the current problem is to find ways to streamline the process and minimise the costs associated with functionalized APP flame retardants, as well as to use them effectively in industrial production. We hope that this review can provide valuable hints and insights for the practical application of functionalized APP in EP and perspectives for future research. [ABSTRACT FROM AUTHOR]

In recent years, bamboo seems to have attracted the attention of researchers due to its advantages over synthetic polymers including being renewable, environmentally friendly, and fully biodegradable. Bamboo fibers at (9, 13, and 18 wt%) are filled with epoxy resin and the effects of mixing the bamboo fibers on mechanical properties were studied. In this paper, the tensile properties and performance of natural bamboo fiber powder-reinforced epoxy polymer matrix-based composites were investigated at three different curing temperatures ranging from T26 °C, T38 °C, and T50 °C. The results showed that the tensile strength and Young's modulus of the bamboo fiber/epoxy composites increased at T26 °C are 41.6 MPa and 2.84 GPa, respectively, for particle size 0.52 μm at a weight loading of 13 %. The increase in tensile strength is due to the excellent fiber matrix interface adhesion. However, it was found that the samples tested under T26 °C for bamboo fiber-reinforced epoxy composites acquired better tensile strength than those tested under the high temperatures of T38 °C and T50 °C. According to the analysis of the flexural characteristics of bamboo particle/epoxy composites, the composite with 1.5 μm particle size has the highest flexural strength at 13 wt% weight loading, measuring 105 MPa. The composite with a 1.5 μm particle size at 18 wt% loading records the maximum impact strength of, 5593 J/m2. This work provides a new approach for the development of lightweight and high-strength composite from natural fiber and polymer.

This study examines the relationship between the size of copper particles and the properties of epoxy resin. Epoxy resin is a type of thermosetting resin commonly used as a matrix in polymer matrix composite materials reinforced with glass or carbon fibers. As part of this study, three microscale and two nanoscale composite samples modified with copper oxide particles of varying sizes were produced. This study included mechanical property tests such as static tensile tests, static bending tests, and impact tests. The results of the strength tests were compared to modeling results. Additionally, an accelerated thermal aging process was conducted to determine the impact of external conditions on the behavior of the produced composites. This study concluded with an analysis of thermal conductivity. The test results revealed that the size of the copper particles significantly impacted the tested properties. The composites with copper oxide particles on the nanoscale demonstrated the best results. These composites have promising applications in the automotive and aviation industries due to their strength, resistance to external factors, and increased thermal conductivity, suggesting their potential for producing materials that effectively dissipate heat. [ABSTRACT FROM AUTHOR]

The mechanical performance of carbon fiber reinforced polymer (CFRP) is a crucial parameter influencing the effectiveness of CFRP reinforcement. The addition of nano-toughening agents to the resin matrix can effectively enhance the mechanical properties of CFRP. This paper investigates the influence of nano-SiO 2 and MWCNTs content (0.2, 0.4, and 0.6 wt%) as well as their blending ratios (1:3, 1:1, 3:1) on the tensile properties of CFRP plates using the vacuum assisted resin infusion molding (VARIM) process. Additionally, an assessment is conducted to evaluate how the tensile performance of CFRP plates affects the CFRP plate/steel interface performance.The results indicate that the resin viscosity increases with the addition of nano-toughening agents, with the resin viscosity experiencing a respective increase of 32.9% and 92.7% when incorporating 0.6 wt% nano-SiO 2 or MWCNTs compared to pure resin. The inclusion of nano-toughening agents enhances the tensile strength of CFRP plates, with a more pronounced effect observed when adding 0.4 wt% nano-SiO 2 or MWCNTs, resulting in respective increases of 41.5% and 31.5% compared to pure CFRP plates. When nano-SiO 2 and MWCNTs are mixed, the tensile performance of the CFRP plate is inferior to that of plates with the same individual nano-toughening agents content. This is attributed to the excessively high viscosity of the resin matrix during mixing, hindering complete infiltration of carbon fibers. Therefore, in the manufacturing process of CFRP plates using the VARIM technique, it is advisable to consider resins with lower viscosity. Additionally, the utilization of CFRP plates with superior tensile performance contributes to enhanced CFRP/steel interface properties, although the tensile performance of CFRP plates does not alter the bonding slip curve of CFRP/steel double-lap joint specimens. • Effect of nano-toughening agent content on composites. • Synergistic effect of nano-SiO 2 with MWCNTs. • Influence of CFRP plate properties on CFRP/steel interface properties. [ABSTRACT FROM AUTHOR]

The epoxy resin-based (ESB) intumescent flame-retardant coatings were modified with 1,4-butanediol diglycidyl ether (14BDDE) and butyl glycidyl ether (BGE) as diluents and T403 and 4,4′-diaminodiphenylmethane (DDM) as curing agents, respectively. The effects of different diluents and curing agents on the flame-retardant and mechanical properties, as well as the composition evolution of the coatings, were investigated by using large-plate combustion, the limiting oxygen index (LOI), vertical combustion, a cone calorimeter, X-ray diffraction, FTIR analysis, a N2 adsorption and desorption test, a scanning electron microscope (SEM), a tensile strength test, and a viscosity test. The results showed that the addition of 14BBDE and T403 promoted the oxidation of B4C and the formation of boron-containing glass or ceramics, increased the residual mass of char, densified the surface char layer, and increased the specific surface area of porous residual char. When their dosage was 30%, ESB-1T-3 coating exhibited the most excellent flame-retardant properties. During the 2 h large-plate combustion test, the backside temperature was only 138.72 °C, without any melting pits. In addition, the peak heat release rate (PHRR), total heat release rate (THR), total smoke production (TSP), and peak smoke production (PSPR) were reduced by 13.15%, 13.9%, 5.48%, and 17.45%, respectively, compared to the blank ESB coating. The LOI value reached 33.4%, and the vertical combustion grade was V-0. In addition, the tensile strength of the ESB-1T-3 sample was increased by 10.94% compared to ESB. In contrast, the addition of BGE and DDM promoted the combustion of the coating, affected the ceramic process of the coating, seriously affected the formation of borosilicate glass, and exhibited poor flame retardancy. The backside temperature reached 190.93 °C after 2 h combustion. A unified rule is that as the amount of diluent and curing agent increases, the flame retardancy improves while the mechanical properties decrease. This work provides data support for the preparation and process optimization of resin-based coatings. [ABSTRACT FROM AUTHOR]

Phenyl polyhedral oligomeric silsesquioxane (POSS) is modified onto the GO surface by using the strong π–π coupling between a large number of benzene rings at the end of the phenyl POSS structure and the graphite structure in the GO sheet, realizing the non-covalent functionalization of GO (POSS-GO). The POSS-GO-reinforced EP (POSS-GO/EP) composite material is prepared using the casting molding process. The surface morphology of GO before and after modification and its peel dispersion in EP are examined. Furthermore, the mechanical properties, cross-sectional morphology, and reinforcement mechanism of POSS-GO/EP are thoroughly examined. The results show that the cage-like skeleton structure of POSS is embedded between the GO layers, increasing the spacing between the GO layers and leading to a steric hindrance effect, which effectively prevents their stacking and aggregation and improves the dispersion performance of GO. In particular, the 0.4 phr POSS-GO/EP sample shows the best mechanical properties. This is because, on the one hand, POSS-GO is uniformly dispersed in the EP matrix, which can more efficiently induce crack deflection and bifurcation and can also cause certain plastic deformations in the EP matrix. On the other hand, the POSS-GO/EP fracture cross-section with a stepped morphology of interlaced "canine teeth" shape is rougher and more uneven, leading to more complex crack propagation paths and greater energy consumption. Moreover, the mechanical meshing effect between the rough POSS-GO surface and the EP matrix is stronger, which is conducive to the transfer of interfacial stress and the strengthening and toughening effects of POSS-GO. [ABSTRACT FROM AUTHOR]

Epoxy resin (EP) is widely used in automobiles, aerospace, electrical and electronic fields. However, the overloading of flame retardant will heavily deteriorate the mechanical properties of EP. In this paper, flame retardant nanosheets (FH) with hierarchical layered structure was self-assembled by combining ferrocene formaldehyde (Fc-CHO) and hexa-aminophenoxy-cyclotriphosphazene (HACP) through a nucleophilic reaction. The limiting oxygen index (LOI) of the EP/FH2 nanocomposite with a 2 wt% loading of FH increased to 31.3% and the UL-94 V-0 rating was achieved due to the multiple synergistic flame retardant effects between ferrocene and cyclotriphosphazene, as well as the barrier performance of the FH nanosheets. Simultaneously, in the cone calorimeter (CC) test, the peak heat release rate (pHRR) and total smoke production (TSP) were reduced by 30.2% and 19.0% compared with EP, respectively. What's more, toughness of the EP/FH2 nanocomposite were greatly improved owing to the low loading and good compatibility of FH nanosheets in EP. In short, this work provides valuable insights into the design of flame retardant nanosheets and targets to balance the flame retardancy and mechanical properties of EP with low addition amounts. [Display omitted] • The flame retardant nanosheets (FH) with hierarchical layered structure were successfully synthesized by self-assembly. • The 2 wt% loading of FH endowed the epoxy resin with excellent fire retardancy. • The synergistic charring mechanism of FH in EP was proposed. • The hierarchical layered structure of FH nanosheets significantly enhanced the mechanical performance of EP. [ABSTRACT FROM AUTHOR]

Natural and synthetic fibers offer a multitude of advantages within the automotive sector, primarily due to their lightweight properties, including appealing characteristics such as adequate mechanical strength, low density, improved acoustic–thermal insulation, cost-effectiveness, and ready availability. In this study, we aimed to strengthen epoxy-based composites with natural and synthetic fibers using bamboo and glass, respectively. Additionally, the reinforcement processing of this hybrid composite material was optimized using a Taguchi L9 (nine experimental runs) orthogonal array design with linear modeling through the Design of Experiment (DoE) principles. The fibers were alkali-treated with sodium hydroxide (NaOH), and the composites were manufactured through the hand lay-up process at ambient temperature and characterized comprehensively using ASTM standard methods. The experimental results of the bamboo–glass fiber composite materials presented a significantly high tensile strength of 232.1 MPa and an optimum flexural strength of 536.33 MPa. Based on the overall Taguchi and linear modeling analysis, the NaOH treatment, fiber content, and epoxy resin concentration were optimized. These findings reveal that the ideal combination consists of 20% fiber content, 8% NaOH treatment, and 65% epoxy resin concentration. The statistical method Analysis of Variance (ANOVA) was employed to confirm the significance of these factors. The integration of the amount (%) of bamboo fiber used played a pivotal role in influencing the mechanical properties of this hybrid composite. Overall, this study demonstrates that the reinforcement of natural fiber with polymeric material composites on epoxy enhanced the composite characteristics and quality. Therefore, this bamboo–glass–epoxy-based composite can be recommended for lightweight structural applications, especially in the automotive sector, in the future. [ABSTRACT FROM AUTHOR]

In this study, the durability of a new polymer carbon fiber-reinforced epoxy resin used to produce composite material in the aerospace field is investigated through analysis of the corrosion phenomena occurring at the microscopic scale, and the related infrared spectra and thermal properties. It is found that light and heat can contribute to the aging process. In particular, the longitudinal tensile strength displays a non-monotonic trend, i.e., it first increases and then decreases over time. By contrast, the longitudinal compressive and inter-laminar shear strengths do not show significant changes. It is also shown that the inter-laminar shear strength of carbon fiber/epoxy resin composites with inter-laminar hybrid structure is better than that of pure carbon fiber materials. The related resistance to corrosion can be improved by more than 41%. [ABSTRACT FROM AUTHOR]

Laser powder bed fusion (L-PBF) additive manufacturing technology can print multi-material parts with multiple functions/properties, and has great potential for working in harsh application environments. However, the metal blank formed by sintering metal powder material with binder added through L-PBF has an obvious porous structure and insufficient mechanical properties, and few studies have been conducted studying this. In this paper, epoxy resin was used to impregnate the blank of porous metal parts formed by L-PBF with iron-based powder material at a certain temperature, and a cross-linked curing reaction was carried out with three kinds of phenolic resin in different proportions under the action of a curing agent, so as to fill the pores and achieve the desired mechanical properties. The characteristic peaks of each group of epoxy resin were characterized using Fourier transform infrared spectroscopy (FT-IR) and H-nuclear magnetic resonance (1H-NMR) spectrums. The microstructure, decomposition temperature, and residue of four epoxy resin dispersion systems were analyzed with a scanning electron microscope (SEM), a thermal gravimetric analyzer (TGA), and derivative thermogravimetry (DTG). The results show that the density of the porous metal parts was obviously improved, the heat resistance temperature of the parts could reach 350 °C, and the tensile strength of the sample after EP2-1 impregnation was increased by 4–6 times after curing at 160 °C for 6 h. Therefore, the use of an epoxy resin dispersion system can increase the porosity of L-PBF porous metal parts, but can also significantly improve their mechanical properties, which can help them to meet the requirements of applications as model materials, biological materials, and functional materials to provide a feasible solution.

Novel flame retardant hybrid composites were developed from lignocellulosic and carbon fibers reinforced with epoxy resin using hot pressing technology. The size of the lignocellulosic fibers was within 0.045 to 0.8 mm, and the carbon fibers ranged from 5 to 8 mm. The nominal thickness of the composites was 10 mm, whereas the nominal density was 730 kg/m3. The composite dimensions were 400 × 400 mm2. The developed panels were tested for internal bonding strength and flexural properties to investigate their mechanical performance. Furthermore, SEM (Scanning electron microscopy) test was conducted to examine the morphologies of the products before and after fracture and found substantial quantities of both types of fiber in the composite system. The EDX (Energy disruptive X-ray) analysis also displayed the chemical elements present in the developed products. Moreover, an FTIR (Fourier transform infrared spectroscopy) study showed strong chemical interactions among the lignocellulosic and carbon fibers with the thermosetting epoxy polymers. The flame retardancy tests of the composite materials also showed significant thermal stability, especially after loading carbon fibers in the composite system. Moreover, dimensional stability showed an improving trend with the increase of carbon fibers as the reinforcement. Overall, the composite materials developed using lignocellulosic and carbon fibers with epoxy resin are showing a novel route to develop composites with high mechanical performance and considerable flame retardancy. [ABSTRACT FROM AUTHOR]

This work deals with developing a self-healing resin designed for aeronautical and aerospace applications. The bifunctional epoxy precursor was suitably functionalized to enhance its toughness to realize good compatibilization with a rubber phase dispersed in the hosting epoxy resin. Subsequently, the resulting mixture was loaded with healing molecules. The effect of the temperature on the epoxy precursor's functionalization process was deeply studied. Fourier trans-former infrared (FT-IR) spectroscopy and dynamic mechanical analyses (DMA) evidenced that the highest temperature (160 °C) allows for obtaining a bigger amount of rubber phase bonded to the matrix. Elastomeric domains of dimensions lower than 500–600 nanometers were found well distributed in the matrix. Self-healing efficiency evaluated with the tapered double cantilever beam (TDCB) method evidenced a healing efficiency for the system functionalized at 160 °C higher than 69% for all the explored fillers. The highest value was detected for the sample with DBA, for which 88% was found. The healing efficiency of the same sample functionalized at 120 °C was found to decrease to the value of 52%. These results evidence the relevant role of the amount and distribution of rubber domains into the resin for improving the resin's dynamic properties. The adopted strategy allows for optimizing the self-healing performance. [ABSTRACT FROM AUTHOR]

In the current study, the nano-composites of unidirectional carbon and glass fiber reinforcedepoxy resin with multi-walled carbon nanotubes (MWCNTs) were separately prepared by hand lay-up and hot pressing of fiber epoxy prepregs. Three types of MWCNT derivatives (parentCNT, low carboxylated CNT (LCCNT) and higher carboxylated CNT (HCCNT)) were dispersed into the epoxy resin/fiber composites. The improved mechanical properties observed in the three component composites could be attributed to the uniform dispersion of CNTs in epoxy/ fiber matrices, nanosize of the additives and the improved interfacial interactions between the composite components. The COOH functional groups could also be effective in the increase of mechanical traits because they induce the amphiphilic nature into CNTs for better dispersion and to generate the better glass fiber/epoxy (E/G) and carbon fiber/epoxy (E/C) interactions. HCCNT led to the best mechanical properties among all the samples due to its higher carboxyl content. HCCNT also changed the curing peak of epoxy in DSC and improved its thermal stability. For instance, the final residual mass for E/HCCNT was 15.4% at 600 °C compared to 13.92% for the pure epoxy while the values of 17.55 and 16.48% were observed at 500 °C for E/HCCNT and epoxy, respectively. The observed effect of COOH functionality on the void formation within the composite and on the better CNT dispersion in the matrix can be considered as an important observation for investigating the E/C/CNTs nanocomposites. [ABSTRACT FROM AUTHOR]

Enhancing the fire safety of epoxy resin (EP) concomitant with less mechanical performance degradation is still a challenge for traditional flame retardants. Hence, polypyrrole (PPy) was used as a film material to fabricate microencapsulated urea ammonium polyphosphate (UAPP) for simultaneously improving the fire safety, thermal stability and compatibility of epoxy composites. The obtained polypyrrole‐coated urea ammonium polyphosphate (PPy‐UAPP) at a load of 10 wt% endows the EP with a UL94 V‐0 rating and a limiting oxygen index (LOI) value of 32.3%, while 10 wt% ammonium polyphosphate (APP) only endows EP with a LOI of 28.5%. Furthermore, the peak heat release rate (PHRR) and peak smoke production rate (PSPR) of EP containing 10 wt% PPy‐UAPP are decreased by 12.3% and 21.4% compared to EP containing 10 wt% APP. The decreased fire hazard of EP/PPy‐UAPP is attributed to the reduction of hazardous gases including CO2 and CO and the generation of more incombustible gases including H2O and NH3 to reduce the combustion intensity. Meanwhile, the good compatibility between EP matrix and PPy‐UAPP endows the resulting EP composites with a superior balance between fire safety and mechanical properties. [ABSTRACT FROM AUTHOR]

Epoxy resin adhesive for pavement is often insufficient in flexibility and toughness. Therefore, a new type of toughening agent was prepared to overcome this shortcoming. To achieve the best toughening effect of a self-made toughening agent on an epoxy resin adhesive, its ratio to the epoxy resin needs to be optimally selected. A curing agent, a toughening agent, and an accelerator dosage were chosen as independent variables. The epoxy resin's adhesive tensile strength, elongation at break, flexural strength, and flexural deflection were used as response values to establish a single-objective prediction model of epoxy resin mechanical property indexes. Response surface methodology (RSM) was used to determine the single-objective optimal ratio and analyze the effect of factor interaction on epoxy resin adhesive's performance indexes. Based on principal component analysis (PCA), multi-objective optimization was performed using gray relational analysis (GRA) to construct a second-order regression prediction model between the ratio and gray relational grade (GRG) to determine the optimal ratio and to validate it. The results showed that the multi-objective optimization using response surface methodology and gray relational analysis (RSM-GRA) was more effective than the single-objective optimization model. The optimal ratio of epoxy resin adhesive was 100 parts of epoxy resin, 160.7 parts curing agent, 16.1 parts toughening agent, and 3.0 parts accelerator. The measured tensile strength was 10.75 MPa, elongation at break was 23.54%, the bending strength was 6.16 MPa, and the bending deflection was 7.15 mm. RSM-GRA has excellent accuracy for epoxy resin adhesive ratio optimization and can provide a reference for the epoxy resin system ratio optimization design of complex components. [ABSTRACT FROM AUTHOR]

Preparing bio‐based epoxy resins with high performance is crucial to sustainable development. However, seeking renewable and flame‐retardant epoxy resins with high mechanical properties are still challenging. Here, we reported a facile way to transform lignin derivatives to intrinsic flame‐retardant epoxy resins with satisfactory mechanical properties. Two guaiacol‐based novolac epoxy resins (i.e., GTEP/DDM and GPEP/DDM) were prepared as alternatives for petroleum‐based DGEBA/DDM. The cured GTEP/DDM product showed a high Tg of 209.5°C, a high tensile modulus of 3.13 GPa, and a high LOI of 28.6% with UL‐94 V‐1 rating, which outperformed DGEBA/DDM system. Specially, GPEP/DDM resin possessed more superior mechanical properties (e.g., tensile strength of 73.9 MPa, and tensile modulus of 5.85 GPa) owing to additional interactions (i.e., π–π interactions and hydrogen bonds), and outstanding anti‐flammability (e.g., LOI of 31.2% with UL‐94 V‐0 rating) due to the endow of phosphorus‐containing groups. The mechanical reinforcement and flame‐retardant mechanisms were clarified based on structural evolution and performance variation. This work provides an efficient synthesis route to achieve a high‐performance thermoset, which is a promising alternative for substituting conventional bisphenol‐A epoxy resin for use as fireproof materials. [ABSTRACT FROM AUTHOR]

This work aims to evaluate the effects of polyamide (PA) and nano‐Al2O3 on the mechanical properties of epoxy resin (EP) and obtain the optimal addition content of PA and nano‐Al2O3. Epoxy matrix composite (EMC) is prepared via the solution blending method using the PA as the curing agent, toughening agent, and the nano‐Al2O3 modified with the silane coupling agent as the filler. Then it is tested for tensile, hardness, impact and wear resistance performances. The results show that when the ratio of PA to EP varies in the range of 40 wt.% to 80 wt.%, increasing the PA content can improve the impact toughness and plasticity of EMC but reduce its hardness, tensile strength and wear resistance. When the content of PA is 60 wt.% of EP, the elongation at break and impact strength of EMC are increased by 66.4% and 12.9%, respectively. The mechanical performances of EMC can be enhanced by loading nano‐Al2O3 fillers in a specific range. When the content of nano‐Al2O3 is 2 wt.% of EP, the elastic modulus, the tensile strength and the wear resistance of EMC are increased by 27.9%, 20.8% and 49%, respectively. The research can provide a valid technical reference for the industrial application of EMC materials. [ABSTRACT FROM AUTHOR]

This study investigates the mechanical properties of Luffa cylindrica and snake grass fiber composites prepared with different combinations of fiber and resin. Fibers are produced from natural sources having good mechanical properties and eco-friendly that can be used in various engineering applications such as automobile, aerospace and automotive industries. The Luffa cylindrica and snake grass fibers will be treated for 3 h with alkali (NaOH) chemical treatment. The treated fibers are then developed as Laminate composites using compression molding technique. The composites have been made in five different compositions by varying the weight percentage (wt.%) of the chemically treated Luffa cylindrica and snake grass fibers (combination of maximum 30 wt.%) mixed with epoxy resin and hardener (maximum of constant 70 wt.%). Bonding between the fiber and matrix plays a vital role in influencing the mechanical characteristics of composites. The five samples have been prepared from the five different compositions and undergone various studies to find its mechanical properties such as ultimate tensile test (UTS), impact test, flexural test and water absorption test. It is found that the UTS and flexural strength have been considerably enhanced by sample 2 and impact strength has been notably increased by sample 3. The microstructure of tensile-tested specimen is observed by using the Scanning Electron Microscopy (SEM). It is reported that the better bonding between the fibers and matrix has been observed by SEM microstructural analysis. [ABSTRACT FROM AUTHOR]

In this study, the first magnetic ceramic nanoparticles were produced utilizing the hydrothermal method. The properties of the nanoparticles were studied utilizing a variety of distinct analytical tools, including an X-ray diffraction pattern, a scanning electron microscope, an infrared absorption spectrometer, and a vibration sample magnetometer. Then, the polymer matrix nanocomposite (PMNC) was fabricated using epoxy resin and made into nanoparticles. In the next step, various analyses, such as microhardness, tensile strength, and flame tests, were taken from the PMNC samples, and the results were compared. The results showed that nanoparticles with a fine and uniform structure and high purity are produced and also have magnetic properties. Furthermore, by adding nanoparticles to epoxy resin and improving surface and mechanical properties, flame resistance is also improved. [ABSTRACT FROM AUTHOR]