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The growing demand of laminated composite materials made of natural fibers and resins with a lower environmental impact in different applications requires a more detailed understanding about the performance during its service considering the delamination in curved parts are one of the most critical failure mechanisms. The present study focuses on an experimental investigation and calculation of the interlaminar tensile strength of unidirectional flax/epoxy laminated curved beams featuring varying thicknesses. The assessment is conducted through a four-point-bending test, in accordance with the ASTM D6415 standard, and the outcomes are subsequently correlated with the employed formulae. The study also involves an examination of the formulation and methodology applicability for the ILTS calculation of unidirectional flax/epoxy laminated curved beams. The analysis includes the impact on maximum interlaminar tensile stress and the evolution of delamination in the flax/epoxy laminated curved beams post-failure behavior. These findings have significant implications for accurately predicting the interlaminar tensile strength and post-failure behavior of such laminated curved beams. [ABSTRACT FROM AUTHOR]

This study explores the effect of hybridization of both resin and reinforcement on mechanical properties of jute/cotton fiber-reinforced epoxy/polyester composite materials. Tensile, bending, and Charpy impact tests were conducted on the composites. Mechanical properties of the composites were observed to increase after hybridization. For reference, tensile strength of jute/epoxy/polyester and cotton/epoxy/polyester hybrid composites was observed to be 10.06% and 12.25% higher than jute/epoxy and cotton/epoxy composites, respectively. The existence of an interpenetrating polymer network between the two resins during hybridization causes enhancement in mechanical properties. The materials have applications in automobiles and aerospace due to their lightweight and improved strength. [ABSTRACT FROM AUTHOR]

Epoxy resin is a thermosetting resin with excellent mechanical properties. It has been pointed out that there are problems on its mechanical properties due to poor polymerization of the epoxy ring caused by water and chlorine impurities during resin production. In this study, we focused on the electrochemical behavior during curing reaction of epoxy resin. To investigate the electrochemical reaction, galvanostat meter was used to measure the voltage behavior during chemical reaction. Molecular Orbital (MO) method was used to understand the mechanisms of voltage behavior during curing reaction. Furthermore, the effect of water existence during curing reaction was investigated by experimentally and analytically. As a result of experimental electrochemical reaction, we successfully measured the voltage behavior associated with the curing reaction. In the case of MO analysis, the epoxy and curing agent models were prepared. Before the reaction, each molecule had zero charge, but after the reaction, it was confirmed that the epoxy had a positive charged and the amine had a negative charged. It is thought that the voltage could be observed due to the movement of this charge during curing reaction. It has been also demonstrated through experimentation and analysis that water accelerates the curing reaction. It was observed that the accelerating effect amplifies as the quantity of water increases. Building upon these results, it was confirmed that the factor leading to the increase in voltage is due to the amount of water. To examine the presence of chlorine impurities during the production of epoxy resin, MO analysis was conducted on the production reaction of epoxy prepolymers. The findings indicated that as the water content increases, the reaction that results in the production of by-products is amplified. This outcome suggested that by-products were already incorporated during the formation of the epoxy. In conclusion, this study provides significant insights into the electrochemical behavior during the curing reaction of epoxy resin, the role of water in accelerating the reaction, and the impact of chlorine impurities during resin production. The findings pave the way for further research to optimize the production process and enhance the mechanical properties of epoxy resin. [ABSTRACT FROM AUTHOR]

Himalayan nettle fibre is abundantly available in the Himalayan regions of India and can effectively replace synthetic fibre in epoxy-based polymer composite synthesis. Fibre from nettle plants can be extracted by water, dew, controlled microbial retting, enzymatic treatment, and mechanical decortication methods. Cellulose (>86 wt.%) is the principal constituent of this fibre. In this study, epoxy-based composites were prepared with 0, 15, 20, 23, 25, 27, and 30 wt.% fibre loadings and investigated the influence of fibre content on thermal, mechanical, and physical properties. The samples were analysed with X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, universal testing machine, dynamic mechanical analysis, thermogravimetric analysis, density and void fraction measurement, and water absorption test. It was found that mechanical and thermal properties were increased with the increase in fibre loadings, attaining the maximum values at 23 wt.%, which signified the improvement in mechanical and thermal properties with fibre reinforcement. The fibre fraction of 23 wt.% resulted in the higher tensile (57.69 MPa), flexural (98.60 MPa), impact (0.689 J) strength, better thermal stability, higher storage modulus (1390.90 MPa), loss modulus (413.05 MPa), and crystallinity (40.5%). This study concludes 23 wt.% fibre loading as optimum reinforcement for the studied epoxy polymer. [ABSTRACT FROM AUTHOR]

Two epoxy resins (flexible and rigid) with new formulations that are more respectful of the environment are used to make five blends of epoxy resins in different proportions reinforced by 30% date palm fibers (DPF). The purpose is to determine how the blend's composition and the addition of DPF affect the material's thermal, water absorption, and viscoelastic properties. It was found that water absorption increases with the increase of flexible epoxy content. The incorporation of DPF multiplies the water absorption by about 6. Thermogravimetric analysis (TGA) revealed that the maximum degradation temperature (Tmax) increases with increasing flexible epoxy content. The incorporation of DPF causes a slight decrease in Tmax. Dynamic mechanical analysis (DMA) showed that raising the amount of flexible epoxy reduces the storage modulus (E') while expanding the size of the transition zone. Conversely, the incorporation of DPF increases E' over the studied temperature range. Similarly, increasing the percentage of flexible resin decreases the glass transition temperature (Tg) from 65.15 °C (100% rigid) to 29.75 °C (100% flexible). On the other hand, the incorporation of DPF improves the Tg. Isochronous stress-strain curves revealed that, at room temperature, the R50S50 epoxy (50% flexible + 50% rigid) and the R50S50R composite (R50S50 + 30% DPF) have linear viscoelastic behavior for tensile stress of 0.5 MPa and nonlinear one for higher stresses. The Schapery model was successfully used to model the nonlinear viscoelastic behavior of R50S50 epoxy and R50S50R composite. [ABSTRACT FROM AUTHOR]

This study focused on the mechanical behavior of hybrid polymeric nanocomposites with 0.1 wt% and 0.2 wt% of multi-walled carbon nanotubes (MWCNTs). Moreover, the fiber orientation effect on the mechanical properties of the hybrid nanocomposites was investigated. Mechanical properties of the hybrid nanocomposites of Glass/Carbon/Basalt fibers were determined. It was observed that addition of MWCNTs in the epoxy resulted in enhancement in the mechanical properties. The hybrid composite and hybrid nanocomposite panels were made using vacuum assisted resin transfer molding (VARTM) method. Test specimens were cut from the composites using waterjet machine cutting and tested in accordance with American Society for Materials Testing (ASTM) standards. From the experimental tests, it was observed that the hybrid nanocomposite with 0.1 wt% of MWCNTs showed improved tensile strength, compressive strength, flexural, and interlaminar shear properties at comparatively low cost. The finite element analysis of hybrid composite and hybrid nanocomposite with 0.1 wt% and 0.2 wt% of MWCNTs were carried out in ANSYS program to validate the experimental results. The experimental results and simulation results were compared with each other. A good correlation between the computational and experimental test results were observed. [ABSTRACT FROM AUTHOR]

AbstractUtilizing furfurylated veneers to improve the quality of plywood has not been extensively studied before. This study investigated the characteristics of plywood made from furfurylated rubberwood (Hevea brasiliensis) veneers at various modification levels. Rubberwood veneers were first impregnated with furfuryl alcohol (FA) at different concentrations (40%, 70%, and 100%) with 3% citric acid as a catalyst for FA polymerization at 103 °C. The weight percent gain (WPG), dynamic mechanical analysis (DMA), and functional groups of the furfurylated veneers were analyzed. The furfurylated veneers were then used to form three layers of plywood using either polyurethane (PU) or epoxy resin as the adhesive. Various physical, mechanical, and morphological properties of the furfurylated plywood were characterized. The WPG of the veneers impregnated with 40%, 70%, and 100% FA were on average 32.2%, 54.1%, and 67.9%, respectively. DMA and ATR-FTIR analyses revealed differences between the control veneers and the furfurylated veneers. Furfurylation slightly decreased the bonding strength of PU-bonded plywood at 100% FA, while the epoxy-bonded plywood remained unchanged at all FA concentrations. Furfurylation reduced the delamination values of plywood, particularly for treatments with 40% and 100% FA. Moreover, the use of 100% FA reduced the thickness swelling, water absorption, and leaching values of the plywood after seven days of water immersion by 43.6%, 73.9%, and 73.8% with PU adhesive, and by 85.7%, 69.6%, and 80.2% with epoxy adhesive, respectively. The formation of furfurylated plywood in this study opens potential opportunities for using low-quality veneers from fast-growing wood species as substitutes for high-quality veneers from natural forests. [ABSTRACT FROM AUTHOR]

Highlights The electromagnetic properties of epoxy‐based composites filled with carbon‐coated copper (Cu@C) nanoparticles and multi‐walled carbon nanotubes (MWCNTs), along with hybrid MWCNT/Cu@C/Epoxy systems containing varying concentrations of nanoinclusions, were systematically investigated across multiple frequency and temperature ranges. Measurements were conducted in the low‐frequency range (20 Hz–1 MHz) and over a temperature span of 40–500 K, as well as in the microwave frequency range (26–37 GHz) at room temperature. The percolation threshold was identified at approximately 2.5 vol% for composites containing only Cu@C nanoparticles and at 0.3 vol% for composites with MWCNTs. Notably, the hybrid MWCNT/Cu@C/Epoxy composites exhibited significantly enhanced electromagnetic properties compared to those of the single‐filled systems. At room temperature, an epoxy composite containing 5 vol% Cu@C and 1 vol% MWCNT exhibits a conductivity of approximately 4 × 10−2 S/m, which increases by nearly two orders of magnitude following a thermal cycle up to 500 K. The total electromagnetic interference (EMI) shielding effectiveness in the 26–37 GHz range was measured between 4 and 9 dB, indicating the material's promising potential for attenuating microwave noise. Dynamic mechanical analysis (DMA) results revealed that increasing the MWCNT content improved the storage modulus of the composites but led to a reduction in the glass transition temperature (Tg), which was observed to range between 40 and 50°C. The incorporation of MWCNTs and Cu@C nanoparticles into epoxy matrices offers a promising approach for the development of lightweight multifunctional composites with superior electrical, mechanical, and EMI shielding properties. The percolation threshold in MWCNT/Epoxy composites is 0.3%. The percolation threshold in Cu@C/Epoxy composites is 2%. The conductivity value of MWCNT/Cu@C/Epoxy composites is around 4 × 10−2 S/m. The total shielding effectiveness in the Ka‐band range between 4 and 9 dB. Glass transition temperature of MWCNT/Cu@C/Epoxy is between 40 and 50°C. [ABSTRACT FROM AUTHOR]

Introducing dynamic ester bonds into epoxy–anhydride resins enhances the reprocessability of the crosslinked network, facilitated by various types of transesterification catalysts. However, existing catalysts, such as metal salts and organic molecules, often struggle with dispersion, volatility, or structural instability issues. Here, we propose to solve such problems by incorporating a liquid-state, thermally stable transesterification catalyst into epoxy resins. This catalyst, an imidazole derivative, can be uniformly dispersed in the epoxy resin at room temperature. In addition, it shows high-temperature structural stability above at least 200 °C as the synergistic effects of the electron-withdrawing group and steric bulk can be leveraged. It can also effectively promote transesterification at elevated temperatures, allowing for the effective release of shear stress. This property enables the thermal recycling and reshaping of the fully crosslinked epoxy–anhydride resin. This strategy not only enhances the functionality of epoxy resins but also broadens their applicability across various thermal and mechanical environments. [ABSTRACT FROM AUTHOR]

The weakness of the fiber–matrix interface restricts the practical application of basalt fiber (BF) as a reinforcing material. In order to improve the interfacial adhesion between the BF and epoxy matrix, surface activation of the BF was carried out using low-pressure O2 and H2-Ar plasma under various conditions. The interfacial shear strength (IFSS), evaluated by a micro-droplet de-bonding test, was adopted to demonstrate the bonding effects at the BF/epoxy interphase. Compared to bare BF, the IFSS between the modified fibers and epoxy matrix was efficiently improved with an increment of 38.4% and 14.4% for O2 plasma and H2-Ar plasma treatment, respectively. Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM) analysis indicated that H2-Ar plasma-treated BF had a much rougher and more rugged surface than O2 plasma-treated samples. X-ray Photoelectron Spectroscopy (XPS) and surface energy results revealed that O2 plasma activation could effectively increase the content of oxygenous groups on the BF surface, thus resulting in a higher total surface energy value. Based on the results, O2 plasma modification at a power of 200 W and pressure of 80 Pa for 0.5 min was considered to be the most favorable condition for the surface activation of BF. [ABSTRACT FROM AUTHOR]

Nowadays, self-healing materials have been studied actively in electronics, soft robotics, aerospace, and automobiles because they can prolong the life span of the materials. However, overcoming the trade-off relationship between mechanical properties and self-healing performance is challenging. Herein, graphene oxide-polyaniline (GO-PANI) filler was introduced to overcome this challenge because GO has a highly excellent modulus, and nitrogen atoms in PANI can endow a self-healing ability through hydrogen bonds. Aside from the hydrogen bond in PANI, the hydrogen bond in the carbonyl group and the disulfide exchange bond in the epoxy matrix also helped the materials heal efficiently. Therefore, the modulus of SV-GPN1 (Self-healing Vitrimer-GO-PANI1) reached 770 MPa, and a 65.0% healing efficiency was demonstrated. The modulus and self-healing efficiency were enhanced after adding GO-PANI filler. The self-healing ability, however, deteriorated when adding more GO-PANI filler because it hindered the collision between the molecules. Meanwhile, SV-GPN1 was excellent in reproducibility, which was proven by the experiment that 16.50 mm thick SV-GPN1 also displayed a self-healing ability. Thus, SV-GPN1 can be applied to structural materials in industries like aerospace because of its self-healing ability, excellent modulus, and reproducibility. [ABSTRACT FROM AUTHOR]

We report on an in situ FTIR study of the thermo-oxidative degradation of a flexible epoxy resin. Different and complementary approaches to the analysis of the spectral data were employed, providing a detailed description of the process in terms of kinetics and mechanisms. A preliminary normal coordinate analysis, based on the DFT method, allowed for a reliable interpretation of the observed spectrum, increasing the amount of available structural information. Two-dimensional correlation spectroscopy provided details on the evolution of the reacting network structure. The relative stability of the various functional groups was ranked, and the most likely sites of initiation were identified. Oxygen fixation on the network chains produced amide and ketone groups, with the latter developing at a higher rate. The kinetic profiles of various functional groups were accurately simulated by a first-order, biexponential model, which allowed a quantitative comparison among their relative stabilities. The spectroscopic analysis allowed us to propose likely mechanisms and to identify those that occur preferentially. [ABSTRACT FROM AUTHOR]

Highly cross‐linked thermosets possess superior mechanical properties and have found broad applications in engineering. However, due to the dense cross‐links, it is extremely challenging to recycle highly cross‐linked thermosets, causing serious environmental and sustainable concerns. Herein, a mechanochemical recycling strategy is proposed for highly cross‐linked thermosets via the synergy of mechanics and chemistry, which is economic‐friendly and pollution‐free. To demonstrate the strategy, diverse metal‐complex catalysts are employed to recycle highly cross‐linked epoxy incorporated with switchable covalent bonds at certain pressure, temperature, and time. The effect of each catalyst on the efficiency of recycling is evaluated, which follows a descending order: Zr4+ > Mn3+ > Co3+ > Fe3+ > Co2+ > Zn2+ > OTi4+ > Ni2+. The results show that the mechanical properties, such as Young's modulus, ultimate strength, peak strain, impact strength, flexural modulus and strength, as well as thermal stability of the recycled samples are almost identical to those of as‐synthesized ones. The effectiveness of the method is further confirmed via micromorphology. [ABSTRACT FROM AUTHOR]

Highlights This study is an attempt to develop high‐quality hybrid composites via functionalization (for homogeneous distribution) of the graphene nanoplatelets (FGNP) and then doping to carbon fiber reinforced especial aviation epoxy matrix (Araldite LY5052) via vacuum bagging molding (VBM). The utilized materials were characterized by UV–Vis spectroscopy, tensile, impact, hardness tests, and fracture mode analysis using a scanning electron microscope (SEM). The results revealed a 92% (502.5 MPa) and 85% (490 MPa) improvement in tensile strength values by doping the 1 and 1.5 wt% FGNPs, respectively. There was an improvement in impact strength with the addition of FGNP; a 28% (3.23 J/mm2) increase was achieved in the nanocomposite with 1 wt% FGNP added, and there was a decrease again in the nanocomposite with 1.5 wt% FGNP added. However, it was still 12% (2.83 J/mm2) better than the neat composite. In addition, the results of examining the fractured surface structures of the impact and tensile test specimens were compatible with these results. It reveals a significant separation of fiber‐matrix bonds with 1.5 wt% FGNP contribution. While tensile and impact strengths peak at 1 wt% FGNP value and decrease afterward, hardness values increase in parallel with the increase in FGNPs. Composites were developed by functionalized graphene nanoplatelets (FGNP). The fiber‐matrix interface was strengthened with FGNP interphase. A 92% tensile strength increase was achieved with 1 wt% FGNP additives. 28% in impact strength and 55% in hardness increase by 1 wt% FGNP. The morphology confirmed that the FGNP interphase filled the interface. [ABSTRACT FROM AUTHOR]

Epoxy is an important thermosetting polymer for wide range of structural applications like aerospace, automobile, and civil construction. It is brittle in nature due to the formation of a high degree of the crosslinking network during the curing process, which is responsible for crack initiation and fracture. Recently, researchers have used various metal oxides as nanofillers in epoxy matrices to prevent cracking propagation in epoxy polymer and enhance their mechanical and thermal properties. The synergetic effects in these nanocomposites are further improved with the reinforcement of a second filler material to widen the range of their applicability. The current review article presents an exhaustive review of Titanium Dioxide reinforced hybrid nanocomposites for their mechanical and thermal properties. The synthesis of hybrid nanocomposites provides multidimensional variabilities for advanced materials. In the present analytical study, the synthesis routes, advantages and challenges offered by hybrid epoxy nanocomposites, and the enhanced properties exhibited by hybrid nanocomposites for different applications are discussed in detail. An overview of the usage of epoxy hybrid nanocomposites in the fields of automobiles, aerospace, civil, anti-corrosion coating, electronics devices, and biomedical has been presented. The future trends of epoxy nanocomposites for potential utilization have been emphasized in this review. [ABSTRACT FROM AUTHOR]

Owing to the outstanding properties of boron carbide (B4C) particles, material researchers have shown potential in filler‐reinforced polymer composites. The present work studied the implication of B4C fillers on the mechanical and ballistic properties of glass fiber epoxy reinforced composites. Two different weight percentages of 2 and 4 wt% B4C fillers were used to modify the epoxy resin. The composite samples with glass fabric woven were made through compression molding. The results show that the tensile, flexural, interlaminar, impact strength and hardness of glass fiber composite were improved by addition of 2 wt% of B4C. The high‐velocity ballistic tests were conducted on the unfilled and B4C filler‐reinforced composites using a 9 mm parabellum projectile with an initial striking of 372 ± 15 m/s. The least back face signature (BFS) and highest specific energy absorption (SEA) were observed for 2 wt% B4C filler composite. Adding B4C filler enhanced matrix toughening and interfacial bonding between fiber and matrix. Matrix cracking and fiber breakage result in the least ballistic resistance for unfilled composite. Fracture behavior was studied on tensile, impact, and ballistic‐tested samples using scanning electron microscopy. The fractured surfaces of filler‐reinforced composite demonstrated good interfacial bonding, matrix hardening, and fiber pullouts. Highlights: The addition of B4C with epoxy up to 2 wt% improves the mechanical and ballistic properties of the composites.The least back face signature and highest specific energy absorption were observed for 2 wt% B4C filler composite.B4C filler enhanced matrix toughening and interfacial bonding between fiber and matrix.Failure of unfilled glass fiber composites is a combination of matrix cracking, fiber pullout, and interface debonding. [ABSTRACT FROM AUTHOR]

2024 aluminum alloy has high strength, processing performance, and good damage tolerance performance, but it is prone to intergranular corrosion and pitting. Therefore, the development of corrosion protective coatings is essential for the aluminum alloy. In this paper, cerium ion (Ce3+) was doped into chitosan‐modified montmorillonite (Ce‐CS‐MMT) by ion exchange method, and the corrosion protective performance of Ce‐CS‐MMT epoxy coating (Ce‐CS‐MMT/EP) was investigated. The electrochemical analysis of aluminum alloy in cerium‐containing solution showed the corrosion inhibition efficiency reached 95.52%. The result indicates the corrosion inhibition effect of cerium‐containing solution was better than pure NaCl solution and MMT solution. The corrosion study of the coating illustrates that the protection rate of Ce‐CS‐MMT/EP reached 95.82%, which was higher than that 91.83% of Ce‐MMT/EP. The result indicates the resistance of charge transfer was greater and the better shielding effect for electrolyte corrosion ions than MMT and Ce‐MMT epoxy coatings, and the corrosion protective performance was excellent. [ABSTRACT FROM AUTHOR]

The growing need for sustainable materials in engineering applications has led to increased interest in the use of waste-derived ceramics as reinforcing fillers in polymer composites. This study investigates the mechanical and tribological performance of epoxy composites reinforced with Yttria-Stabilized Zirconia (YSZ) waste ceramics, focusing on the effects of varying ceramic content (0–40 wt.%). The results demonstrate that while the tensile strength decreases with increasing ceramic content, the wear resistance and surface hardness improve, particularly at 20 wt.% YSZ. These findings are highly relevant for industries such as automotive, aerospace, and industrial manufacturing, where the demand for eco-friendly, high-performance materials is growing. This work aligns with the journal's focus on sustainable engineering by offering new insights into the practical application of waste materials in high-performance composite systems. [ABSTRACT FROM AUTHOR]

This study aimed to address the environmental concerns associated with petrochemical-derived bisphenol-A, commonly used in epoxy resin synthesis, by developing an eco-friendly alternative utilizing bio-based ascorbic acid, or vitamin C. The epoxy compound was synthesized by leveraging the hydroxyl group inherent in ascorbic acid through a reaction with epichlorohydrin. Optimal curing conditions were determined via dynamic scan and isotherm analysis using Differential Scanning Calorimetry (DSC) for the newly synthesized epoxy resin in combination with isophorone diamine (IPDA) as the curing agent. The cured product, obtained under the identified optimal curing conditions, exhibited a soft hardened form with a tensile strength of 7.5 MPa and an elongation of 6%. These findings underscore the feasibility of synthesizing a commercially viable eco-friendly epoxy resin utilizing ascorbic acid, thus contributing to the ongoing pursuit of sustainable material alternatives. The results suggest potential scalability for mass production, emphasizing the significance of this approach in addressing the demand for environmentally friendly materials in various industrial applications. Synthesis of ascorbic acid-based epoxy resin. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effects of three toughening agents—core–shell rubber particles (CSR), nano-silica particles (NSPs), and epoxidized polybutadiene (EPB)—on the performance of UV-LED-cured epoxy electronic encapsulants. By systematically comparing the curing behavior, thermomechanical properties, and impact resistance of different toughening agents in alicyclic epoxy resins, their potential applications in more environmentally friendly UV-cured electronic encapsulation are evaluated. The results show that NSP and CSR toughened samples have fast cured speed under 365 nm UV-LED light, but it affects the depth of curing under low energy conditions. They maintain high Tg, high modulus, and low thermal expansion coefficient (CTE), especially in the NSP-toughened sample. The EPB-toughened sample has good transparency for LED, but it has negative effects on Tg and CTE. This research provides essential theoretical and experimental data to support the development of high-performance UV-LED-cured epoxy encapsulation materials. [ABSTRACT FROM AUTHOR]

Solid lubricants are added to polymers to upgrade their tribological properties, especially in cases where adhesive and abrasive friction are valid. However, there are not enough studies on the effects of solid lubricants on particle erosion. This study investigated the effects on solid particle erosion behavior of three different well known solid lubricants (molybdenum disulfide, polytetrafluoroethylene, and graphite). These solid lubricants were added at three different ratios (5, 10, and 15 wt.%) to the two different type (rigid and toughened) epoxy resins. Garnet abrasive particles (180–400 μm) were blasted to the sample surface under 1.5 bar for 15 s to conduct solid particle erosion tests. The erosive wear mechanisms of neat and solid lubricant‐reinforced epoxy resins were investigated in relation to the epoxy type, solid lubricant type, and solid lubricant reinforcement ratio. Statistical analysis was performed according to response surface methodology to support the experimental results, and ANOVA tables were obtained. The wear and deformations that occurred on the surface after solid particle erosion were examined using a noncontact optical profilometer system and scanning electron microscopy, and a significant relationship was detected between the deformation on the surface and particle erosion. Analysis results showed that the factor causing the greatest erosion rate change was the epoxy resin type. Finally, it has been observed that all solid lubricants reduce the erosive wear resistance, and this resistance decreases as the weight ratio increases. Highlights: Investigations were conducted into the erosion behavior of two types of epoxy resins: rigid and toughened. The toughened epoxy resin exhibited greater resistance to erosion. Although it has the same type of content, on average, rigid epoxy worn 2–4 times more than toughened epoxy.The effect of adding polytetrafluoroethylene tended to increase the erosion rate of both rigid and toughened epoxy resin less than that of other solid lubricants.Graphite particles increased the erosion rate of toughened epoxy by 1.5–3 times and that of rigid epoxy by 2–3 times, depending on the value of the reinforcement ratio.MoS2 increased the erosion rate of toughened epoxy by 1.5–3 times and that of rigid epoxy by 2–3 times.Using a noncontact optical profilometer (for investigating surface topography), it was proven that there is a significant relationship between the erosion rate and roughness characteristics. Wear mechanisms were identified by SEM analysis. [ABSTRACT FROM AUTHOR]

This study delineates the dependence of thermophysical behavior of acid‐epoxy vitrimers on their formulation. The stress relaxation due to the bond exchange reaction and the glass transition temperature of acid epoxy vitrimers are investigated, with respect to the influence of catalyst content and acid chain length. This is carried out for a range of dicarboxylic acids and catalyst concentrations formulated and characterized using calorimetry and dynamic mechanical analysis. The influence of acid chain length on the bond exchange rate, topological transition, and glass transition temperatures of the vitrimers is found to be significant. The activation energy of the exchange reaction varies over a wide range from 73 to 104 kJ/mol and the topology freezing temperature from 66 to 136°C with the behavior governed by the interplay between crosslinking density, network flexibility and density and distance of functional groups, with an increase of catalyst concentration leading to lower topological transition temperature and the dependence on chain length showing non‐monotonic behavior. The glass transition decreases by about 30°C as the carbon chain length increases from 6 to 14 carbons due to enhanced monomer flexibility and is not affected by the concentration of catalyst. [ABSTRACT FROM AUTHOR]

The increasing responsibility to sustain the environment ecofriendly paves the way to the development of materials with bio or synthetic waste. The goal of this study is to produce uniform dispersion of bio-ceramic Habesha eggshell particles (ESPs) in an epoxy matrix and to investigate damping characteristics under dynamic mechanical analysis for lightweight applications. Lightweight composites were fabricated by dispersing the 70 μm ESPs in varied weight percentages of 2.5, 5, 7.5, and 10, achieved through a novel pulverization process, in the epoxy matrix using a magnetic stirrer. The XRD investigation revealed a reduction in the crystallinity index with decreasing peaks as the eggshell fraction rose. The addition of 10% ESPs increased the heterogeneity in composites thus enhancing the thermal stability with the shift of glass transition temperature to the scale of 6.9 °C. The increased area under the loss modulus curve observed for a higher percentage of ESPs acknowledges the improved heat absorption capacity and 35% improvement in damping characteristics. Few theoretical models were employed to acknowledge the strengthening mechanism to uphold the thermal stability of the composite. The theoretical results show a minimal error percentage compared to the experimental results. The inclusion of ESPs in the epoxy matrix promises better thermal stability and damping characteristics. [ABSTRACT FROM AUTHOR]

The exothermic nature of acrylate photopolymerizations enables room temperature 3D printing of a quaternary formulation that incorporates an acrylate monomer, and an epoxy/thiol‐ene system (ETES). The latter comprises an epoxy monomer, a multifunctional thiol and a tetraallyl functionalized ditertiary amine curing agent. Pristine ETES necessitates temperatures of 85–95 °C for curing. Several mechanisms operate simultaneously during this process: homopolymerization of acrylates, thiol‐acrylate photopolymerization, thiol‐ene photopolymerization between the double bonds of curing agent and the multifunctional thiol, the Michael addition between thiolates derived from ETES and the double bonds of acrylates, and the anionic polymerization of the epoxy resin via the tertiary amine groups. To optimize the quaternary formulations for printing, parameters, such as reactivity, exothermicity, and viscosity, was explored. Subsequently, the thermal and viscoelastic properties of the printed cross‐linked polymers derived from these formulations were analyzed using Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA) and Thermogravimetric Analysis (TGA). The polymers derived from quaternary formulations exhibited lower crosslinked density compared to those obtained from the pristine acrylates. This reduction in crosslink density contributes to the improved toughness of the hybrid polymers. [ABSTRACT FROM AUTHOR]

AbstractThermosets, before hardening, consist of independent macromolecules similar to thermoplastics, however, chemical curing of these macromolecules via heat or radiations may form irreversibly crosslinked macromolecular networks between their main chains. Graphene quantum dots are inimitable spherical nano-entities having the advantages of extremely small sizes, of 5-10 nm, very high surface area, surface/edge effects, quantum confinements and a range of physical characteristics including semiconductivity, fluorescence and magnetic properties. Similar to other nanocarbons (like graphene, fullerene or nanodiamonds), graphene quantum dots have been examined as noteworthy nanofillers to enhance the essential physical features of various macromolecular matrices, such as thermosets, thermoplastics and rubbers. Consequently, this review article was intended to systematically discuss the existing scientific state of graphene quantum dots reinforced thermosetting macromolecular matrices for the formation of high performance nanomaterials. According to the literature reports, the type, amount and molecular weight of these macromolecules seemed to affect the epoxy-quantum dots interactions and physical properties, like strength and heat stability of the resulting nanomaterials. Moreover, including graphene quantum dots in thermosetting matrices, like epoxies, hyperbranched polyesters and hyperbranched polyurethanes, has positively influenced the engineering aspects (mainly mechanical and thermal attributes) of the resulting nanocomposites owing to their interactions, compatibility and interfacial tendencies toward these matrices. Principally, epoxy/graphene quantum dots nanocomposites have been fabricated and investigated for the effects of graphene quantum nano-entities on the physical property enhancements of these irreversibly crosslinked macromolecules due to their mutual matrix-nanofiller interfaces. As per our analysis, the literature hitherto on the graphene quantum dots reinforced thermosetting matrix nanocomposites has disclosed significant property improvements of these macromolecules and their promising technological applications for high performance anticorrosion coatings, electromagnetic interference shields and biomedical fields. [ABSTRACT FROM AUTHOR]

Highlights Establishing a robust interfacial bond between hexagonal boron nitride (h‐BN) plates and the epoxy matrix is essential for enhancing heat transfer, which is difficult because of h‐BN's low‐surface energy, tendency to clump together, and the chemical inertness of the epoxy matrix. This research shows different techniques for treating the surface of h‐BN fillers by applying acids and thermal processes to activate the surface. The silanization process was used to increase the silane content on the surface of activated h‐BN in order to make it more compatible with the epoxy matrix. X‐ray photoelectron spectroscopy analysis revealed silicon peaks (Si2s peak at 150.1 eV and Si2p peak at 100.3 eV) in the spectrum of silane‐treated samples. Heat treatment resulted in the production of more oxygen molecules on the shell of h‐BN compared to the acid treatment. Here, the primary focus was on examining how surface treatment affects thermal conductivity (TC) performance in both in‐plane and through‐thickness paths. There was an increase in the epoxy's TC perpendicular to the plane, going from 0.21 to 0.47 (W/mK), showing a remarkable 123.8% enhancement by adding 10 wt% of silane‐modified‐thermal treated h‐BN particles. The improvement resulted from effectively silanizing the exterior boundary of h‐BN particles, enhancing connection and distribution in the epoxy matrix. Surface modification of h‐BN‐epoxy composites improves TC, leading to better heat conduction in thermal management systems, benefiting industries like aerospace, automotive, and energy systems. Silanization of h‐BN for better filler‐matrix bonding leading to improved heat transfer Boosting thermal conductivity in the through‐thickness direction with surface‐modified h‐BN Significant improvement in through‐thickness thermal conductivity with treated h‐BN. Thermal treatment of h‐BN produced better oxygenation than acid treatment. Application in aerospace and automotive through improved heat transfer. [ABSTRACT FROM AUTHOR]

Self-healing composites are smart materials that can self-detect and prevent micro crack propagation and any catastrophic failure in the composite structure. In this study, dicyclopentadiene (DCPD) monomer was encapsulated with urea formaldehyde (UF) by in situ polymerization. These microcapsules were mixed with epoxy, chopped carbon fiber (CF), and multi-walled carbon nanotubes (CNT) to make self-healing composite. Both microcapsules and the composite specimens were extensively tested for their physical, thermal, and mechanical properties. The average diameter and shell thickness of the microcapsules were 268 µm and 805 nm, respectively. DMA analysis suggested that the microcapsules have a glass transition temperature (Tg) of 85°C. FTIR analysis confirmed the presence of CF, multi-walled carbon nanotubes (MWCNT), and other constituents in the composite. The tensile strength of the self-healing composites was tested as per ASTM standards. The incorporation of MWCNT in the composites has significantly improved the tensile strength of the composite without compromising on the self-healing efficiency (90%) compared the unmodified samples (72%). The encouraging results of higher glass transition temperature (85°C) combined with an improved healing efficiency (90%), can be considered as the novelties of this work. As the test results of microcapsules and composite specimens were encouraging, they can find applications in making composite structures for aerospace, windmills, and marine applications. The experimental observations and test results are discussed in detail. [ABSTRACT FROM AUTHOR]

Owing to their ability to provide thermal conduction as well as electrical insulation properties that are required for modern electronic devices and electrical systems, nano-fillers incorporated epoxy composites are being widely investigated. In this study, epoxy composites have been reinforced with boron nitride nanosheets (BNNSs) to achieve enhanced thermal conductivity and dielectric properties. Further, their change as a function of BNNSs concentration (weight %) has been investigated. BNNSs are synthesized using the bottom-up approach, while the nanocomposites of epoxy and BNNSs are fabricated with the help of a process involving stirring and ultrasonication. The results reveal that the incorporation of BNNSs leads to enhancement of thermal conductivity of the nanocomposites and it increases with an increase in the loading of BNNSs. The increase in thermal conductivity is 1.93 W/mK with 15 weight % of BNNSs, that is ~ 865% improvement over the pure epoxy. Also, an approximately 123% increase in dielectric constant has been observed. These results demonstrate the potential of BNNSs as nano-fillers in preparing epoxy nanocomposites with better thermal management and energy storage capacity. [ABSTRACT FROM AUTHOR]

The aim of this study is to determine experimentally the higher material parameter g$g$ of a metamaterial with a triangular substructure and to verify a higher‐gradient elasticity model for beams with internal substructures or microstructures. The investigations of the higher‐gradient elasticity models of Bernoulli‐Euler and Timoshenko beams with a periodic triangular substructure in Khakalo et al. show that the bending stiffness strongly depends on the geometrical parameters of the lattice structure. To achieve this goal, beams with triangular substructures were additively manufactured using fused deposition modeling and stereolithography. They were experimentally investigated in tensile and bending tests. Three different types of beams with triangular substructures were produced, consisting of one, two and four layers of triangular beams, using two different materials: Polylactide and epoxy resin. The higher material parameter g was quantitatively determined based on the experimental results using inverse analysis. The results are valid for these specific variations of the substructure and can adequately represent the elastic size effects. In addition, this study investigates the relationship between the bending stiffness and the geometric parameters of the lattice structure as well as the influence of the curing time on the elastic properties of epoxy resin. The experiments involved testing the triangular beams under tensile and bending loads. The numerical and experimental results were compared using digital image correlation. Based on the experimental data, a higher gradient material parameter representing the geometric structure of the lattice was determined. [ABSTRACT FROM AUTHOR]

In this study, two different Al2O3-TiO2 and SiO2-TiO2 hybrid TiO2 particles were synthesised by using silica (SiO2) and alumina (Al2O3) to suppress the photocatalysis of TiO2. Key variables such as the concentration of the hybridization material (C), heating temperature (Th), and calcinating temperature (Tc) were selected with performance measured by photodegradation rate. The Taguchi L9 orthogonal array, a systematic approach used in the design of experiments (DOE), confirmed A333 (Al2O3-TiO2) achieved 99% photodegradation suppression with photodegradation rate reduced significantly from 0.01305 min-1 to 0.00009 min-1 and improved yellowing resistance by 63%, while S323 (SiO2-TiO2) achieved 75% suppression with photocatalysis activity decreased from 0.01305 min-1 to 0.0033 min-1 and 42% improved resistance. X-ray Diffraction (XRD) analysis showed A333 had a higher rutile phase (40.1% vs. 10.2% for S323), and Fourier Transform Infra Red (FTIR) and Field Emission Scanning Electron Microscopy (FESEM) analyses revealed A333's rougher surface and lower surface area compared to S323 and pure TiO2. Overall, A333 effectively suppressed photocatalysis and improved yellowing resistance of epoxy thin film. [ABSTRACT FROM AUTHOR]

Nanodiamond has been categorized among remarkable zero dimensional nanocarbon. This carbon nanoparticle has been applied as important nanofiller in the polymeric matrices. This state-of-the-art review article portrays fundamentals, physical properties, and prospects of nanodiamond filled thermosetting matrices. Among thermosets, most research efforts have been reported on the nanodiamond filled epoxy and polyurethane matrices. Consequently, the epoxy/nanodiamond and polyurethane/nanodiamond nanocomposites have been designed. The nanodiamond nanoparticle addition in polymers caused microstructural variations and enhancements in mechanical, thermal, wear, adhesion, and related advanced features. The property improvement was observed due to the nanofiller dispersion, matrix-nanofiller interactions, and interface formation. Type of thermosetting polymer, curing agent, nanodiamond content, nanodiamond functionalities, and processing method define the final nanocomposite architecture, morphology, and ensuing characteristics. Consequently, the high-tech epoxy/nanodiamond nanocomposites and polyurethane/nanodiamond nanocomposites exposed capability toward technological relevance like coatings, microwave absorption, and biomedical. As few thermosetting matrices have been used with the nanodiamond nanofillers so far, more comprehensive future efforts are needed to disclose the actual potential of thermosetting polymer/nanodiamond nanocomposites. [ABSTRACT FROM AUTHOR]

The success of composite materials is attributed to the nature of bonding at the nanoscale and the resulting structure-related properties. This study reports on the interaction, electronic, and optical properties of diamond nanothread/polymers (cellulose and epoxy) and boron nitride nanotube/calcium silicate hydrate composites using density functional theory modeling. Our findings indicate that the interaction between the nanothread and polymer is due to van der Waals-type bonding. Minor modifications in the electronic structures and absorption spectra are noticed. Conversely, the boron nitride nanotube–calcium silicate hydrate composite displays an electron-shared type of interaction. The electronic structure and optical absorption spectra of the diamond nanothread and boron nitride nanotube in all configurations studied in the aforementioned composite systems are well maintained. Our findings offer an electronic-level perspective into the bonding characteristics and electronic–optical properties of diamond nanothread/polymer and boron nitride nanotube/calcium silicate hydrate composites for developing next-generation materials. [ABSTRACT FROM AUTHOR]

This study investigates the correlation between the interface structure and macroscopic dielectric properties of polymer-based nanocomposite materials. Utilizing bisphenol-A (BPA) epoxy resin (EP) as the polymer matrix and the commonly employed layered phyllosilicate montmorillonoid (MMT) as the nanometer-scale dispersive phase, nano-MMT/EP composites were synthesized using composite technology. The microstructure of the composite samples was characterized through XRD, FTIR, SEM, and TEM. Changes in the morphology of the nanocomposite interface were observed with varying MMT content, subsequently impacting dielectric polarization and loss. Experimental measurements of the dielectric spectrum of the nano-MMT/EP were conducted, and the influence of the material interface, at different nano-MMT contents, on the dielectric relaxation was analyzed. The study delves into the effect of the nanocomposite interface structure on ion dissociation and migration barriers, exploring the ionic conductivity of nano-MMT/EP. Lastly, an analysis of the impact of different nano-MMT contents on the dielectric conductivity is presented. From the experimental results, the arranging regularity of polymer molecules in the interface area raises. In the matrix, the ion migration barriers decrease significantly. The higher the MMT content in the interface, the lower the migration barrier is. Until the MMT content exceeds the threshold, the agglomerated micro-particles form, which decreases the polymers' space distribution regularity, and the ions migration barrier raises. According to the changes in the rule of the ions migration barrier with the composite interface structure content, the reason for dielectric conductivity changes can be judged. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) are extensively utilized in the fabrication of high-performance composites due to their exceptional mechanical, electrical, and thermal characteristics. To investigate the mechanical properties of CNTs filled polymers accurately and effectively, a 3D modeling approach that incorporates the microstructural attributes of CNTs was introduced. Initially, a representative volume element model was constructed utilizing the modified nearest neighbor algorithm. During the modeling phase, a corresponding interference judgment method was suggested, taking into account the potential positional relationships among the CNTs. Subsequently, stress–strain curves of the model under various loading conditions were derived through finite element analysis employing the volume averaging technique. To validate the efficacy of the modeling approach, the stress within a CNT/epoxy resin composite with varying volume fractions under different axial strains was computed. The resulting stress–strain curves were in good agreement with experimental data from the existing literature. Hence, the modeling method proposed in this study provides a more precise representation of the random distribution of CNTs in the matrix. Furthermore, it is applicable to a broader range of aspect ratios, thereby enabling the CNT simulation model to more closely align with real-world models. [ABSTRACT FROM AUTHOR]

Metal corrosion is a challenge for the world with heavy impacts on the economy. Study on the development of effectiveness anticorrosion additives is a promising strategery for the protection industry. This research focuses on the modification of hydrotalcite Mg−Al (HT) loading tannic acid (TA) with 3‐(trimethoxy silyl) propyl methacrylate organo‐silane (TMSPM) for applicating as an anti‐corrosion additive for epoxy coating on the steel substrate. The suitable ratio of HT and modifiers was investigated and the suitable content of modified HT in epoxy matrix was found based on mechanical properties of the epoxy‐based coating. The characteristics of modified HT were assessed through infrared (IR) spectroscopy, X‐ray diffraction pattern (XRD), scanning electron microscopy (SEM), thermal gravimetry analysis (TGA), water contact angle (WCA), dynamic light scattering (DLS). Detailly, HT‐TA3‐S3 shows good stability in distilled water when HT/TA was modified with TMSPM which makes Zeta potential decreases significantly. Besides, SEM analysis presented HT‐TA‐S has a cylindrical shape about of 500 nm. Moreover, the crystallite size of HT/TA after being modified by TMSPM decreases sharply. All of these prove successfully synthesize HT loading TA with modified TMSPM. Water contact angle (WCA) decreases in case of loading TA and increases in case of modifying with TMSPM (WCA changed from HT (116.3°) to HT‐TA (102.4°) and HT‐TA‐S (120.1°) which indicates the increased hydrophobicity of the sample. The obtained results showed HT/TA was modified successfully with TMSPM. The modification affected the size distribution and surface properties of HT nanoparticles while it did not impact on the crystal structure of HT. After incorporating modified HT/TA into the epoxy coating, the adhesion of coating to steel substrate was improved significantly. Consequently, the adhesion of epoxy/3 wt. % modified HT/TA coating was increased 3 times as compared to epoxy neat (from 0.76 MPa to 2.77 MPa). In addition, the relative hardness and gloss retention of epoxy/3 wt. % modified HT/TA coating reached the maximum values as compared to the others. Owing to salt spraying results, the epoxy/3 wt. % modified HT/TA exhibited an excellent anticorrosion ability for the steel substrate. All the above results show the potential of HT nanoparticles loading TA modified with TMSPM as anticorrosive additives for protective coatings on steel substrates. [ABSTRACT FROM AUTHOR]

Recently, bio-composites have attracted much attention due to their potential applications in various industries. The most notable benefits are the product's low cost, biodegradability, lightweight, availability, and ability to solve environmental issues. The present research utilizes ash gourd (Benincasa hispida) peel, a food waste, as a filler material to produce epoxy (EP) composites. The effect of ash gourd peel particle percentage (ranging from 0 to 25 wt.%) was studied on the developed composites' mechanical and thermal properties and water absorption behavior. The maximum tensile strength, flexural strength, and shore D hardness were 47.52 MPa, 2409.17 MPa, and 79.6respectively, when the ash gourd peel was 5% by weight in the composite. It was observed that the mechanical characteristics of manufactured bio-composites are negatively affected by the high concentration of ash gourd peel particles in the epoxy matrix. Also, increasing ash gourd peel particle fraction increases the water absorption of composites when immersed in distilled, sea, and tap water. The composite with 5% filler by weight absorbs water at a minimal rate when immersed in seawater. Thermogravimetric analysis was conducted to investigate the newly developed composite's thermal behavior. In addition, a morphological examination of the fractured surfaces was carried out with assistance from a scanning electron microscope. The work presents ash gourd peel particles as the potential alternative to be used as filler in composites. [ABSTRACT FROM AUTHOR]

The mechanical properties of fiber metal laminates (FML) are influenced by several various factors. Interface adhesion plays a particularly crucial role in interlaminar strength. Enhancing the interlaminar strength of carbon fiber reinforced aluminum laminate (CARALL) composites present a persistent challenge due to inherent weaknesses between metal and composite elements. Therefore, this study focuses on improving the interlaminar performance of CARALL composites by introducing cellulose paper interlayer at the metal/composite interface. The cellulose paper interlayer offers the advantage of being cost-effective and sustainable. Cellulose paper-interleaved CARALL composites were fabricated by vacuum bagging method and exhibited noteworthy improvements in mechanical properties. Comparative analysis with pristine samples revealed substantial enhancements, including a 15% increase in tensile strength, a remarkable 42% improvement in flexural strength, and a significant enhancement in mode-I fracture toughness by 65%. Furthermore, the cellulose paper interleaving played a crucial role in stabilizing fracture formation at the fiber-matrix interface, with mode II fracture toughness witnessing a 3% increase. Visual examination revealed the underlying toughening processes occurring in the interfacial area. This innovative approach of interleaving laminated composites with cellulose paper emerges as a sustainable and effective strategy, demonstrating the potential to fortify and toughen the interlaminar zones of CARALL composites. [ABSTRACT FROM AUTHOR]

Adhesives play an important role in modern society's production and daily life. Developing robust and sustainable adhesives remains a great challenge. Here we report a sustainable epoxy-vitrimer adhesive with high adhesive strength (about 10 MPa) and reusability (82% strength after 3 times). This adhesive can be fabricated from commercially available products through a straightforward hot-pressing method without the need of solvents. The adhesive process is also simple, requiring only 30 min at 180 °C. In addition, the vitrimer adhesive has the advantages of both erasability for reuse and excellent water resistance. This work provides a facile strategy to fabricate high-strength adhesive that ensures reusability, recyclability, low cost of raw materials, and simple processing technology. Simultaneously, it expands the range of potential applications for epoxy vitrimers. [ABSTRACT FROM AUTHOR]

Realizing multiple locked shapes in pre-oriented liquid crystal elastomers (LCEs) is highly desired for diversifying deformations and enhancing multi-functionality. However, conventional LCEs only deform between two shapes for each actuation cycle upon liquid crystal-isotropic phase transitions induced by external stimuli. Here, we propose to regulate the actuation modes and the locked shapes of a pre-orientated epoxy LCE by combining dynamic covalent bonds with cooling-rate-mediated control. The actuation modes can be adjusted on demand by exchange reactions of dynamic covalent bonds. Derived from the established actuation modes, such as elongation, bending, and spiraling, the epoxy LCE displays varied locked shapes at room temperature under different cooling rates. Various mediums are utilized to control the cooling rate, including water, silicone oil, and copper plates. This approach provides a novel way for regulating the actuation modes and locked shapes of cutting-edge intelligent devices. [ABSTRACT FROM AUTHOR]

The main objective of this study is to investigate the effect of curing temperature on the mechanical properties of hemp fiber reinforced polymer (HFRP) composites. In this study, hemp fiber was considered as a reinforcement and epoxy resin with hardener as a matrix. The mercerization process was used to remove contaminants from the fiber surface. The overall volumetric fraction used was 40% fiber and 60% matrix. One composite sample was cured at open temperature (27 ± 3 °C) for 15 days and others at elevated temperatures such as 80, 120 and 160 °C for various durations such as 1, 2, and 3 h (h). Different mechanical tests were performed under ASTM standards to examine the mechanical performance of HFRP composites. The tensile and compressive properties such as Young's modulus, tensile and compressive strengths are higher in the specimens cured at 120 °C for 3-h. The flexural strength and stiffness are maximum in the composites cured at 80 °C for 3-h. The maximum interlaminar shear strength representing the composite's resistance to delamination is observed at 120 °C for 3-h curing condition. The Fourier transform infrared (FTIR) study identifies that the chemical treatment has reduced the impurities present on the fiber surface. Scanning electron microscopic (SEM) studies indicate better fiber/matrix adhesion in specimens cured at elevated temperatures than those cured at open temperature. Finally, this study emphasizes that curing at elevated temperature (120 °C for 3-h) improves the mechanical performance of the NFRP composites. [ABSTRACT FROM AUTHOR]

A comparative study on three types of fireproofing coatings (namely, cementitious, sodium silicate, and epoxy) was made to determine their effectiveness in protecting steel structures. The effects of these coatings on the external protection of steel were structurally, thermally, and mechanically studied. The prepared cementitious coatings endured the heat until 1200 °C for 1 h showing dimensions stability without deformation nor cracking during firing. Both crushing strength (CS) and bulk density measurements decreased from 69 to 18 kg/cm2 and from 1.62 to 1.00 g/cm3 'respectively' with increasing both perlite and vermiculite percentages. Six of the prepared 48 sodium silicate and epoxy coatings succeeded in bearing heat until 900 °C for 3.5 h sustaining the steel substrates' temperature below 60 °C following the Underwriters Laboratory-94 (UL-94) standard. This protective effect was due to the formation of a hard glassy phase on the steel surface isolating it from the heat by the action of the applied constituents. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) thermograms for these succeeded samples revealed that they gave a high residual weight ranging from 63 to 88% when tested from room temperature up to 900 °C. Performing the scanning electron microscopy (SEM) test revealed that physical blending between both the binder and additives (other coating ingredients') has occurred. The results concluded that the used ingredients, which have low prices, compared to the imported ones, and are locally available, are recommended for the fire protection of steel. [ABSTRACT FROM AUTHOR]

This study examines the upgrading of mechanical properties in basalt fibre composites through the incorporation of microfiller. Because of their remarkable mechanical qualities and environmentally beneficial qualities, basalt fibres are becoming more and more popular in a wide range of engineering applications. However, to further expand their utility, improvements in mechanical properties like tensile strength, flexural strength, and impact resistance are essential. In this research, clamshell filler, an abundant waste material from seafood processing, is employed as a reinforcing agent in basalt fibre composites. Clamshells are found on the sea water and participate in marine ecosystems. They are derived from dead clams with no flesh in it. The research offers a solution to the disposal problem of clamshell waste by incorporating it into composite materials- a value-added product, offering both material performance benefits and sustainability. Dead clams are used to prepare the clamshell powder which is made into fine powder of 64-90 micron after cleaning and drying process. This size of micro-filler added in basalt fibre through hand layup fabrication techniques. A series of experiments and material characterization techniques are examined to know the effects of varying clamshell filler content (0, 5, 10 wt.%) on the mechanical performance of the composites. Mechanical test like tensile, flexural, microhardness and impact tests are done to evaluate the material's strength, stiffness, and resistance to external forces. The results show enhancements in the mechanical properties of basalt fibre composites with the addition of clamshell filler. The findings suggest that the utilization of clamshell filler can effectively improve the tensile and flexural strengths and hardness of the basalt fibre composites. Moreover, there is an increment of impact resistance which indicates the potential applications of composite in impact-prone industries. [ABSTRACT FROM AUTHOR]

The aim of this research was to develop a lightweight, asbestos-free brake friction material using sisal, jute, and sisal/jute hybrid composites along with fillers and frictional additives. Sisal, jute, and sisal/jute hybrid fiber–reinforced epoxy polymer-filler-based composites were prepared using a compression molding process, and their mechanical and tribological properties were evaluated as per ASTM standards. The results were compared with commercial brake friction material. The study found that the compressive strength of sisal, jute, and hybrid composites increased by 21%, 11.6%, and 16.65%, respectively, while the hybrid composite (S3 + J3) exhibited nearly equivalent compressive strength. The impact strength, hardness, and water and oil absorption behavior of the hybrid composite exhibited the same performance as that of commercial brake pads. A pin-on-disc experiment was conducted and the results showed that wear loss and coefficient of friction decreased with an increased weight percentage of fiber. Scanning electron microscopy images depicted uniform dispersion, distribution, and defect-free laminates with a uniform wear track. Overall results suggest the potential use of these composites in brake pad applications. Therefore, this study presents the development of sisal-jute fiber epoxy filler–based hybrid composites for lightweight applications, which can be used as a substitute for asbestos in brake pads. [ABSTRACT FROM AUTHOR]

In this study, glass fiber and flax fiber reinforced with epoxy and ZnO nanofiller were used to create composites utilizing the hand layup method. The purpose of this study is to develop a novel hybrid polymer‐matrix composite that can be employed in various application areas such as aerospace, sports, medical equipment, railways, etc. The fabricated composite was made with epoxy as a matrix material reinforced with nano‐ZnO, glass fiber, and flax fiber. Six fiber layers with varying fiber orientations were inserted into the matrix in a specific stacking order. The results show the maximum tensile, flexural, impact, and ILSS as the values of 264.74 MPa, 492.12 MPa, 595.72 J/m, and 50.05, respectively. Along with the mechanical properties, Physical characterization such as density, void content, thickness swelling, moisture content, and water absorption tests were conducted. FE‐SEM test was conducted to check the uniformity of nanoparticles in the matrix material and the breakdown of fibers. [ABSTRACT FROM AUTHOR]

In this work, mild steel as a substrate was coated by electrodeposition in a bath mixed with nickel sulfate (NiSO4·6H2O), nickel chloride (NiCl4·6H2O), and boric acid (H3BO3) using nanocomposite cetyltrimethylammonium bromide, hBN, and epoxy with hardener. The experiments were designed using the Taguchi method through the L9 orthogonal array to reduce the number of experiments. The input parameters for the design of experiments were taken: the time (min), voltage (V), and the hBN concentration (wt-%). The coated samples were tested for their tribological, corrosion, and adhesion performance using pin-on-disc, electro-impedance spectroscopy, and cross hatch tester, respectively. The tribological results reveal that the coated sample of 3 wt-% hBN concentration at 3 mV voltage and 30-minute deposition time shows the lowest friction coefficient (∼0.42) among all the samples, indicating its superior wear resistance and corrosion resistance. Further, the same sample also outperformed the others, demonstrating the high adhesion (adhesion scale of 5 B) of coating with the substrate. Moreover, the surface was characterized using X-ray diffraction, Fourier transforms infrared, goniometer, and scanning electron microscopy. [ABSTRACT FROM AUTHOR]

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Frontal polymerization has great potential in complementing additive manufacturing processes such as direct ink writing as a continuous cure synchronized to the printing speed can overcome issues such as sagging. To study the incorporation of frontal polymerization into a potential printing process, a frontally polymerizable DGEBA epoxy resin has been developed for both UV and thermal initiation. Through frontal polymerization alone, full conversion is observed with a starting glass transition of 150°C for both initiation methods. Resulting thermal behavior is shown to have little dependence on either initiation irradiance or temperature utilized and much greater dependence on initiator concentration in the resin. Mechanical behavior is maximized by varying initiator concentration and cure conditions achieving tensile stress of 75 MPa and K1C of 1.2 MPa‐m1/2. Shelf stability of the resin proves promising with no viscosity change after 12 weeks of room temperature storage. Future studies will concern adapting the resin for both direct ink writing and continuous fiber additive manufacturing applications. Highlights: Frontal polymerization of EPON 826 using RICFPUtilized a tetrakis borate containing diaryliodonium cationic initiatorStable and polymerizable after 12 weeksResin printed and frontally cured using UV initiation [ABSTRACT FROM AUTHOR]

Abstract Epoxy is a widely used thermosetting resin recognized for its exceptional performance in adhesives, coatings, and various other applications, attributed to its high tensile strength, stiffness, electrical performance, and chemical resistance. Epoxy-clay nanocomposites are extensively employed across diverse industries. The physical and chemical properties of these nanocomposites are influenced by the processing methods, clay modifiers, and curing agents used during their preparation. In this study, epoxy/nanoclay composites based on Diglycidyl Ether Bisphenol-A (DGEBA) will be cross-linked using Isophorone Diamine (IPD), a cycloaliphatic amine, and Triethylenetetramine (TETA), a linear aliphatic amine. The initial phase of the research will assess the impact of different types of cross-linkers, both individually and in combination at various molar ratios (such as Isophorone Diamine: Triethylenetetramine (IPA: TETA) / 25:75 and 75:25), on the compressive strength of the epoxy mortar. In the subsequent phase, the epoxy formulation with an Isophorone Diamine: Triethylenetetramine (IPD: TETA / 75:25), which demonstrates the highest compressive strength, will be selected for further investigation. This formulation will be used to evaluate the effects of different weight percentages (3%, 5%, and 7%) of organically modified montmorillonite (OMMT). The prepared epoxy composites will be characterized using a range of techniques, including Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM). The epoxy/nanoclay composite with an IPD: TETA / 75:25 and 3 wt % OMMT is expected to show the highest compressive strength, which is 94 MPa.