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Experimental studies of the shock wave properties of two epoxy resins with the same composition but different curing temperatures (160 and 200 °C) at up to 330 GPa pressure have been carried out. Laser interferometry was used to record particle velocity profiles at up to 73 GPa pressure while measuring the shock wave velocity. The release sound velocity was experimentally determined in the 3–73 GPa pressure range. Cumulative explosive shock wave generators were used to study the shock Hugoniot of epoxy resins at pressures above 100 GPa. It was shown that the shock compressibility data of both samples are approximated by a single shock Hugoniot within the experimental error. A kink on Hugoniot recorded close to 25 GPa pressure indicates a chemical decomposition in epoxy resin. Above this kink, a change in the shock wave front structure was recorded. Hugoniots of epoxy resin and unidirectional carbon/epoxy composite were compared at up to 370 GPa pressure. [ABSTRACT FROM AUTHOR]

Surface flashover that occurs on the surface of epoxy resin (EP) is one of the main causes of insulation failure in the power system. The newly emerging polar groups on the surface are highly desirable for enhancing the surface flashover performance of EP. Here, we present a facile ultraviolet (UV) irradiation method to enable the controlled introduction of C–OH and C = O groups on the EP surface. The resultant UV-irradiated EPs (UV-EPs) are highly uniform with little variation in surface roughness while exhibiting tunable polar content with the irradiation time. We also present the first systematic investigation into the effect of UV irradiation time on the surface flashover voltage of UV-EPs, with a maximum increase of 23.07% compared to the pristine EP. Mechanistic studies suggest that the enhancement of the surface flashover voltage is mainly dominated by the density of the deep trap, which is strongly dependent on the UV-induced C–OH and C = O groups on the surface. Besides that, the UV-EPs also display long-term stability due to the stable presence of polar groups, which further demonstrates the feasibility of this method for the development of EP with excellent properties. [ABSTRACT FROM AUTHOR]

Alternating current (AC) loss measurement is crucial for the theoretical evaluation and optimization in the fabrication of superconducting AC devices. Lock-in amplifier based on the lock-in phase is commonly adopted and inevitably involves with phase error. In this work, a novel approach for measuring transport AC loss by determining the minimum compensated voltage (MCV) was developed, in which the lock-in amplifier was removed. Since it just uses the voltage signal from an AC voltmeter, it is phase-error immune. Experimental results demonstrated that when using the lock-in amplifier, there existed a system error as the initial phase difference between the sampled (reference) and real current phases, which required careful compensation. In contrast, the phase error no longer needed to be considered by the MCV method, and the AC loss results were obtained much more conveniently with the relative error between the theoretical and the experimental of less than 5%. Finally, the AC loss of a coated conductor spiral wound on an epoxy bar was obtained using the presented approach, demonstrating its low cost, ease of operation, and high accuracy. [ABSTRACT FROM AUTHOR]

Packaging insulation materials with high thermal conductivity and excellent dielectric properties are favorable to meet the high demand and rapid development of third generation power semiconductors. In this study, we propose to improve the thermal conductivity of epoxy resin (EP) by incorporating a three-dimensional boron nitride thermally conductive network. Detailedly, polyurethane foam (PU) was used as a supporter, and boron nitride nanosheets (BNNSs) were loaded onto the PU supporter through chemical bonding (BNNS@PU). After immersing BNNS@PU into the EP resin, EP-based thermally conductive composites were prepared by vacuum-assisted impregnation. Fourier transform infrared spectrometer and scanning electron microscope were used to characterize the chemical bonding and morphological structure of BNNS@PU, respectively. The content of BNNS in BNNS@PU/EP composites was quantitatively analyzed by TGA. The results show that the thermal conductivity of the BNNS@PU/EP composites reaches 0.521 W/m K with an enhancement rate η of 30.89 at an ultra-low BNNS filler content (5.93 wt. %). Additionally, the BNNS@PU/EP composites have excellent dielectric properties with the frequency range from 101 to 106 Hz. This paper provides an interesting idea for developing high thermal conductivity insulating materials used for power semiconductor packaging. [ABSTRACT FROM AUTHOR]

In order to prepare highly heat-resistant packaging insulation materials, in this paper, bismaleimide/epoxy resin (BMI/EP55) composites with different contents of BMI were prepared by melt blending BMI into amino tetrafunctional and phenolic epoxy resin (at a ratio of 5:5). The microstructures and thermal and electrical properties of the composites were tested. The electrostatic potential distribution, energy level distribution, and molecular orbitals of BMI were calculated using Gaussian. The results showed that the carbonyl group in BMI is highly electronegative, implying that the carbonyl group has a strong electron trapping ability. The thermal decomposition temperature of the composites gradually increased with the increase of BMI content, and the 20% BMI/EP55 composites had the highest heat-resistance index, along with a glass transition temperature (Tg) of >250 °C. At different test temperatures, with increase in the BMI content, the conductivity of epoxy resin composites showed a tendency to first decrease and then increase, the breakdown field strength showed a tendency to first increase and then decrease, and the dielectric constant was gradually decreased. Two trap centers were present simultaneously in the composites, where the shallow trap energy level is the deepest in 20% BMI/EP composites and the deep trap energy level is the deepest in 10% BMI/EP55 composites. Correspondingly, the 10% BMI/EP55 composite had a slower charge decay rate, while the 20% BMI/EP55 had a faster charge decay rate. In summary, the BMI/EP55 composites with high heat resistance and insulating properties were prepared in this study, which provided ideas for preparing high-temperature packaging insulating materials. [ABSTRACT FROM AUTHOR]

We outline a coarse-grained model of epoxy resins (bisphenol-F-diglycidyl-ether/3,5-diethyltoluene-2,4-diamine) to describe elastic and plastic deformation, cavitation, and fracture at the μm scale. For this, molecular scale simulation data collected from quantum and molecular mechanics studies are coarsened into an effective interaction potential featuring a single type of beads that mimic 100 nm scale building blocks of the material. Our model allows bridging the time–length scale problem toward experimental tensile testing, thus effectively reproducing the deformation and fracture characteristics observed for strain rates of 10−1 to 10−5 s−1. This paves the way to analyzing viscoelastic deformation, plastic behavior, and yielding characteristics by means of "post-atomistic" simulation models that retain the molecular mechanics of the underlying epoxy resin at length scales of 0.1–10 µm. [ABSTRACT FROM AUTHOR]

Epoxy insulators in gas-insulated power apparatus are subjected to the combined effects of electrical and mechanical loads. In this work, a simulation model is built based on the energy theory to explore the electrical tree growth of epoxy resin under tensile and compressive stresses. With increasing AC voltage, the electrical tree growth is promoted, exhibiting a morphology with more branches. Tensile stress accelerates the electrical tree growth, while proper compressive stress has the opposite effect. However, when the compressive stress exceeds a certain value, electrical tree growth is promoted again. When the mechanical stress is vertical to the needle electrode, these effects primarily impact the length of the trees. Conversely, in parallel cases, mechanical stress mainly affects the width of the electrical trees. Filler doping play the role of obstacles as well as enhancing the electric field concentration, the electrical tree growth is firstly inhibited and then promoted as the doping content increases. The electrical tree morphologies of simulation and experiment are in good consistency, proving the reasonability of the simulation model. [ABSTRACT FROM AUTHOR]

Aramid fiber (AF)-reinforced epoxy (EP) resin composite materials are widely used in the application of insulation rod-reinforced components, but the adhesion performance between AFs and EP resin is poor, which easily leads to interfacial defects and even gradually develops into breakdown, flashover, and other faults. In this study, a simple, environmentally friendly, diverse, and highly designable layer-by-layer self-assembly modification method was adopted to assemble aramid nanofibers/SiO2 onto the surface of AFs. The modified AFs were then used to produce composite materials with EP resin. By testing the interface breakdown, flashover, and leakage current of the AF/EP resin composite materials, the influence mechanism of AF surface modification on the material interface insulation performance was studied. The results show that the insulation performance of the modified composite material first increases and then decreases with the increase in the number of assembled layers, with the maximum increase in breakdown voltage being 93.56% and the maximum increase in flashover voltage being 30.91%. [ABSTRACT FROM AUTHOR]

With the development of electronic devices and wireless communication technology, the quality of human life has improved. However, shielding from electromagnetic interference (EMI) is required due to device malfunctions and harmful effects on human health. Polymer‐based shielding materials getting much attention due to their light weight, flexibility, good processability, and other desirable traits. However, achieving consistent dispersion of conductive fillers and optimizing the balance between electrical, mechanical, and thermal properties remain challenges despite the advantages of polymer‐based materials. Especially, epoxy resins are promising polymer materials for EMI shielding applications due to their excellent mechanical strength, chemical resistance, and excellent adhesive properties. Additionally, epoxy resin exhibits remarkable processability allowing for various fabrication techniques such as casting, molding, and three‐dimensional printing. However, one of the significant drawbacks of epoxy resin is the difficulty in achieving uniform dispersion of conductive fillers within the epoxy matrix. In this study, we propose an iron‐nickel alloy (FeNi) embedded in an epoxy matrix (FeNi/Epoxy) for EMI shielding material. It is manufactured by facile fabrication process due to the advantages of epoxy, which has excellent processability. EMI shielding effectiveness at 12 GHz is enhanced from 9.12 to 17.86 dB by the increase of FeNi concentrations. Furthermore, thermal and mechanical properties were improved by the increase of FeNi concentration. Thermal conductivity for efficient heat dissipation is increased from 0.63 to 1.49 Wm−1 K−1. Moreover, polydopamine (PDA) was employed as a surface coating material for FeNi to overcome the non‐uniform dispersion of FeNi particles in the epoxy matrix. Surface coating by PDA significantly enhanced the dispersion uniformity and strengthened the adhesion between the filler and matrix. Elastic modulus is greatly increased from 83.03 MPa to 1.29 GPa by the surface coating. The enhancement of mechanical properties is derived from the chemical bonds between the filler and matrix. [ABSTRACT FROM AUTHOR]

A novel surface modification technique for graphite films (GF) to improve the interface thermal resistance with epoxy resin was presented. By utilizing the self‐polymerization of dopamine (PDA), dopamine micro and nanoparticles were formed on the surface of the GF. Subsequently, the surface of the epoxy resin was functionalized with polydopamine (PDA) through grafting of the silane coupling agent 3‐glycidyl ether oxy‐propyl trimethoxy silane (GOPTS), enabling the introduction of epoxy resin groups onto the surface of the GF. Employing a simple folding technique, a three‐dimensional GF network (3DGF) was constructed, in which modified GF was successfully incorporated into the polymer matrix. The results showed that the 3DGF network further promoted the effective transfer of heat and electrons within the composite, leading to a significant improvement in thermal and electrothermal conversion performance. The prepared 3DGPGF/epoxy resin composite exhibits high thermal conductivity (7.14 W/mK) at a relatively low GF loading (31.9 wt%). Under a voltage of 12 V, the surface temperature of the sample rapidly rises from room temperature to 130°C within 200 s, and can completely melt ice cubes within 60 s. These results indicate that epoxy‐silane‐dopamine‐modified graphite film can be a promising candidate material, and this work provides a promising strategy for designing and manufacturing high‐performance composites with improved thermal properties. The developed method has the potential to be extended to other polymer matrices and fillers, and the prepared composites have enormous potential in various applications. [ABSTRACT FROM AUTHOR]

In the process of curing or service, epoxy resin is prone to crack damage due to complex stress, resulting in material performance degradation and other catastrophic accidents. Self‐healing microcapsules offer an effective strategy to address the aforementioned issues and enhance the long‐term durability of materials. However, traditional microcapsules face challenges in achieving non‐contact repair, as the healing agent requires high temperature or other extreme conditions to achieve curing, which necessitates the artificial provision of these conditions. Moreover, such extreme conditions may accelerate equipment aging or negatively impact the matrix material. To address these issues, this paper reports a photosensitive microcapsule that can achieve healing by natural light for non‐contact self‐healing of insulating composites. In particular, SiO2 nanoparticles are incorporated into the shell of the microcapsules to construct a UV shielding layer, effectively preventing premature curing and failure of the untriggered microcapsules. Experimental results indicate that the proposed photosensitive microcapsule@SiO2 exhibits excellent thermal stability, remaining intact at temperatures up to 200°C. With a healing agent content of approximately 77.5%, the photosensitive microcapsule@SiO2 ensures effective repair. Furthermore, when cross‐linked with epoxy resin, it has minimal negative impact on the epoxy matrix, with a slight improvement in mechanical properties. The composites demonstrate outstanding self‐healing performance in response to mechanical scratch damage. Without the need for any artificial stimuli, the healing process can be easily activated by natural light, facilitating intelligent, contactless, and autonomous self‐healing. [ABSTRACT FROM AUTHOR]

Based on the molecular dynamics (MD) simulation of glass transition temperature (Tg) and hydrogen bonding in the composite system of epoxy resin (Ep) and polyethylene glycol (PEG), this work developed shape memory Ep/PEG (EpP) films with controllable thermal response, recycling and reprocessing functions using melt dispersion and polymerizing‐pressing processes. EpP films with different PEG contents exhibit excellent shape memory performance, among which the shape recovery rate of EpP‐5 film can reach 92.7%, which can recover from complex structures to the initial shape. The PEG in the composite system can effectively regulate the thermal and mechanical properties of EpP, especially increasing the strain at break and reducing the Tg. Compared with EpP‐0 film. The Tg of EpP‐15 film increased by 40°C and the strain at break increased by 18.56%. Furthermore, compared with the EpP‐0 film, the recycling‐reprocessing temperature of EpP‐15 film has been reduced by 75°C. In summary, based on MD simulation, shape memory EpP films with controllable thermal response, recycling, and reprocessing functions have been successfully developed, and have shown considerable application prospects in the field of intelligent materials. [ABSTRACT FROM AUTHOR]

The aim of this research was to investigate asphalt effects on the storage stability, mechanical properties and micro‐properties of cold‐mixed epoxy asphalt binder (CEAB). Firstly, four CEAB were prepared with four base asphalt types and storage stability, miscibility analyses were performed by fluorescence microscopy (FM). Then, cured CEAB and epoxy resin (ER) were treated by ultraviolet aging. Tensile test, dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy were applied to clarify the mechanical properties and micro‐properties of aged and unaged CEAB. Also, bending beam rheometer (BBR) tests were conducted to study low‐temperature performance of CEAB. The results revealed that the CEAB prepared with asphalt with penetration grade 60 ~ 80 presented superior storage stability, miscibility, mechanical properties and that prepared with penetration graded 80 ~ 100 showed slightly better low‐temperature performance. Moreover, asphalt properties were found to have little impacts while epoxy resin played a key role in the mechanical properties of CEAB. Glass transition temperature (Tg) of the CEAB containing penetration‐graded asphalt 80 ~ 100 decreased more significantly than that with penetration‐graded asphalt 60 ~ 80, and it was also found that the CEAB prepared with base asphalt with higher molecular weight polydispersity index had better ductility performance. [ABSTRACT FROM AUTHOR]

Materials performance is primarily influenced by chemical composition, making compositional analysis (CA) essential in materials science. Traditional quantitative mass spectrometry, which deconvolutes analyte spectra into reference spectra, struggles with reactive systems where spectral variations occur, such as peak shifts and new peak emergences. Additionally, obtaining reference spectra for all pure constituents is often impractical. To address these challenges, I propose nonlinear reference-free quantitative mass spectrometry (NL-RQMS). This method simultaneously determines composition, reference spectra, and nonlinear interaction effects directly from a spectral dataset of mixtures, eliminating the need for prior reference spectra. In a benchmark test on ternary reactive polymers of epoxy and amines, NL-RQMS inferred compositions with an error margin of just 3 wt%, significantly outperforming the 6 wt% error margin of linear RQMS. The inferred interaction terms clearly indicate in situ reactions between epoxy and amine moieties. This framework enables accurate compositional analysis without prior knowledge of the constituents, even in systems with interactive components, and holds significant potential for applications such as grading recycled plastics, where pristine materials, degradation compounds, and stabilizers interact complexly, causing nonlinear spectral distortions. [ABSTRACT FROM AUTHOR]

Polypropylene double‐grafted maleic anhydride and bisphenol A epoxy resin (PP‐g‐M‐E) was successfully prepared by a single‐step method and characterized by Fourier‐transform infrared spectroscopy. Subsequently, it was employed as a compatibilizer to fabricate polypropylene (PP)/polyethylene terephthalate (PET) blends via melt extrusion. The content of the PET dispersed phase in the composite varied from 0 to 30 phr. The microstructure and morphology of the composites were characterized using scanning electron microscopy and Raman spectroscopy. The addition of PP‐g‐M‐E increased the interfacial interaction between the two phases and improved the compatibility and thermal stability of the system. In the presence of the compatibilizer, the crystallinity of the matrix phase (PP) increased, while that of the dispersed phase (PET) decreased owing to the heterogeneous nucleation effect of uniformly distributed PET. Double grafting of the PP‐g‐M‐E compatibilizer considerably enhanced the mechanical performance of the PP/PET blend system. The elongation at break of the modified sample exceeded that of the PP/PET blends by 117.55%, and the flexural and impact properties also showed considerable improvement. [ABSTRACT FROM AUTHOR]

Balancing the enhancement of flame retardancy of epoxy resin while maintaining its mechanical capacities intact poses a significant challenge in the realm of flame‐retardant epoxy resins. To reach the above objectives, a COF‐based synergistic flame retardant with phosphorus, nitrogen, and silicon (PA‐COF@MT) was synthesized using phytic acid (PA), montmorillonite (MT), and covalent organic framework (COF). When PA‐COF@MT was added at 4 wt%, EP/PA‐COF@MT exhibited a reduction of 42.1% in peak heat release rate (PHRR), 45.84% in total heat release (THR), and 59.8% in total smoke production (TSP) compared with the pure EP. LOI increased by 30.5% and UL‐94 tested to V‐0 grade. flame‐retardant index (FRI) value of 3.03, achieving a "good" rating. Fire growth indices and mean effective combustion heat were increased while mechanical properties also improved. These findings suggest that the flame retarding mechanism of PA‐COF@MT is mainly through vapor phase and condensed phase actions. The combined effects of phosphorus, nitrogen, and silicon make the surface of carbon residue solid and dense, resulting in excellent heat insulation and smoke suppression effects. In simple terms, this study provides new insights into COF‐based flame retardants. Combining low‐cost and simple preparation methods, PA‐COF@MT has broad application prospects in flame‐retardant epoxy resin systems. [ABSTRACT FROM AUTHOR]

Organic flame retardant 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) was used to decorate the pores of mesoporous silica (m‐SiO2) nanospheres to prepare a new composite flame retardant (DK‐SiO2). The content of DOPO in DK‐SiO2 is about 17 wt%. Due to the chemical bonding, DK‐SiO2 not only enhances the flame retardant performance, but also effectively avoids adverse effects of DOPO on the glass transition temperature and mechanical properties of epoxy resin (EP). At 9 wt% loading, the limiting oxygen index of the EP increased from 25.7 to 31.2, and successfully passed the UL‐94 V‐0 rating. Besides, DK‐SiO2 can significantly reduce the peak heat release rate, total heat release, and total smoke production of EP, with reductions of 26%, 32%, and 20.8%, respectively. Compared with the simple blended sample, DK‐SiO2 not only has better flame retardant performance but also shows significant advantages in thermodynamic properties. The glass transition temperature, impact, and tensile strength, as well as storage and flexural modulus have been improved. This excellent flame retardant performance is mainly attributed to the gas‐condensed synergistic flame retardant mechanism between DOPO and m‐SiO2. The good thermodynamic performance is due to the excellent dispersion of DK‐SiO2 nanospheres in the EP. [ABSTRACT FROM AUTHOR]

In this paper, an epoxy structural adhesive was fabricated by using the high‐performance thermoplastic engineering plastic phenolphthalein‐based polyaryletherketone (PEK‐C) as tougheners, and 4,4′‐diaminodiphenylsulfone (DDS) and 4,4‐diaminodiphenylmethane (DDM) as the curing agents. The effect of PEK‐C on the mechanical properties, microstructure, and adhesive properties of the modified epoxy resin system was investigated. Epoxy structural adhesive with 20 phr PEK‐C exhibited excellent bonding performance and thermal stability. The PEK‐C toughened adhesive presented high shear strength of 31.6 MPa and 27.6 MPa at 120°C and 150°C, respectively. The PEK‐C toughened epoxy structural adhesive was then used to bond CF/PEEK composites, and the effects on the bonding properties of CF/PEEK were investigated. By the combined treatment of sandpaper grinding and corona discharge (80 mesh sandpaper sanding + corona treatment for 30 s), the shear strength of the composite joints is increased to 18.73 MPa. And the shear strength retention rate of the joint was 99.8%. The strategy can be used to fabricate sandwich structures with CF/PEEK as the skin with excellent performance. Therefore, PEK‐C toughened modified epoxy resin is conducive to the enhancement of adhesive properties and has a better performance for the bonding of CF/PEEK materials. [ABSTRACT FROM AUTHOR]

Type V linerless hydrogen storage vessels made of all-composite face the challenges of cryogenic mechanical failure and hydrogen leakage of composites. The cryogenic mechanical performance and gas-barrier property of the carbon fiber reinforced polymer for Type V vessels are largely determined by the epoxy matrix. Carbon nanotubes are widely used as polymer reinforcement material to enhance the cryogenic mechanical performance and gas-barrier property of epoxy resins. In this work, multi-walled carbon nanotubes (MWCNTs) were dispersed into epoxy resins to prepare MWCNTs-modified epoxy resins. The cryogenic mechanical performance, gas-barrier and thermal properties of the modified resin were then investigated. The experimental findings revealed a 34.34% reduction in the gas permeability coefficient for the nanocomposites containing 0.9 wt% MWCNTs compared with the epoxy matrix. The tensile strength and failure strain at cryogenic temperature (77 K) experienced enhancements of 26.99% and 41.53%, respectively. In addition, the thermal stability and glass transition temperature of the modified resin were improved. As a result, the MWCNTs-modified epoxy resin exhibits improved gas-barrier property in addition to excellent cryogenic mechanical performance, making it ideal for manufacturing Type V linerless hydrogen storage vessels. • The thermal stability and glass transition temperature of the modified resin are improved. • The tensile strength and failure strain at 77 K improved by 26.99% and 41.53%, respectively. • The gas permeability coefficient of MWCNTs-modified resin decreases by 34.34%. • The mechanism of MWCNTs enhancing resin's gas-barrier and mechanical properties is explained. [ABSTRACT FROM AUTHOR]

In order to achieve flame retardant, hydrophobic, and toughened epoxy resins, phosphorus/fluorine‐containing block copolymer (FBCP) was synthesized by reversible addition‐fragmentation chain transfer polymerization, and then the as‐synthesized PMADOPO‐b‐PHFBA block copolymer was used as additive to modify the epoxy resin, accompanying with a random copolymer (FRCP) serving as control group. It showed that due to the regular arrangement of molecular chains, FBPC formed a fibrous‐like structure at the fracture interface of epoxy/PMADOPO‐b‐PHFBA (EP/FBCP) samples, effectively enhancing the toughness of epoxy composite materials. The fracture energy of EP90/FBCP‐10 was higher than that of EP90/FRCP‐10 and was about twice than that of pure EP. The addition of 3 wt% FBCP could enhance the limited oxygen index (LOI) of EP97/FBCP‐3 to 33.2% and reached a V‐1 UL‐94 rating. As the addition of FBCP increased, the LOI gradually increased. When the addition of FBCP was 10%, the LOI and UL‐94 of EP90/FBCP‐10 was 38.2% and V‐0 grade, respectively. Meanwhile, the presence of fluorine element effectively reduced the surface energy of the composite EP material. Compared with pure EP, the water contact angle of EP90/FBCP‐10 was about 101° with an increasing of 20.8%. Furthermore, the flame‐retardant mechanism of EP/FBCP epoxy composites was discussed. [ABSTRACT FROM AUTHOR]

The effects of grafting level of polyethylene glycol (PEG) grafted styrene ethylene propylene styrene (SEPS) on the intrinsic brittleness of epoxy thermosets were studied. The SEPS‐g‐PEG block copolymer (BCP) was synthesized by grafting various grafting degree of PEG (i.e., 10%, 20%, 30%, and 40%) on polystyrene (PS) blocks of SEPS following Williamson ether synthesis method. A total of 10 wt% of the BCP modifiers were dispersed in epoxy thermosets. PEG side chains were miscible in the epoxy which formed a uniform BCP dispersion within the epoxy thermoset matrix. As the degree of PEG grafting was increased, the BCP phase was absorbed in the epoxy matrix. This absorption occurred because the increase in PEG grafting provided more miscible PEG chains to bind the BCP and epoxy nanostructures together. The differential scanning calorimeter and dynamic mechanical thermal analysis analyses indicated that BCP toughened epoxy exhibited an improved glass transition temperature (Tg). At a 40% PEG grafting degree in the BCP, the critical stress intensity factor (KIC) and critical strain energy release rate (GIC) increased up to 80% and 180%, respectively. This trend suggested that the energy associated with fractures could be absorbed through the deformation of the softer phases when a load was applied to them. [ABSTRACT FROM AUTHOR]

Crack localisation is a fundamental step of damage identification. Most of the published research on crack localisation based on natural frequency consists in model updating which requires a great deal of calculation. This paper presents a simple method of crack localisation in composite cantilever beam-type structures. The proposed method consists of classifying the reduction of the first four measured natural frequencies and deducing the damage position from a table. For these purposes, a finite element model is first used to study the direct problem: the vibration behaviour of an intact beam and the changes caused in the damaged state. Then it is shown that the classification of the frequency reduction ratio is different for each damaged zone. Consequently, the beam is discretized into several areas according to the classifications of the first four frequency ratios. Therefore, this discretization is represented in a table to be used in damage localisation. The robustness of the suggested technique is first tested numerically by using the Abaqus/CAE finite element software environment. Then, the applicability of the localisation method is validated experimentally on a cracked glass fibre-reinforced epoxy beam. The results show that the proposed method can successfully localise damage in composite beams. [ABSTRACT FROM AUTHOR]

9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-N-Aminoethylpiperazine (DOPO-AEP), a phosphorus and nitrogen intumescent flame retardant curing agent was prepared by using acetonitrile as solvent using 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and N-aminoethylpiperazine (AEP) as raw materials. The structure of the flame retardant curing agent DOPO-AEP was analyzed Fourier Transform Infrared Spectrometer (FTIR), Nuclear Magnetic Resonance (NMR) and Electrospray Ionization Mass Spectrometry (ESI-MS), and the synthesis method of the target product was determined. In addition, the content of char residue was determined by thermogravimetric analyzer, and its thermal properties were comprehensively explored, and based on the obtained results, the curable epoxy resin was selected to prepare DOPO-AEP/EP flame retardant composites. According to the amount of DOPO-AEP added product, different proportions of DOPO-AEP/EP flame retardant composites were prepared, and the actual impact of flame retardant properties and mechanical properties of epoxy resin in different proportions was explored. When the content of DOPO-AEP is 35%, the limiting oxygen index of DOPO-AEP/EP reaches 29.9, which has a significant increase compared with the limiting oxygen index of pure epoxy resin of 19.8, but compared with the content of DOPO-AEP of 30%, the limiting oxygen index of DOPO-AEP/EP is 28.7, and there is no significant increase change. Comprehensive analysis shows that when the component content of DOPO-AEP is 30%, the flame retardant system has a tensile strength of 29.0 MPa, an impact strength of 4.5Kj/m2 and a flexural strength of 73.9 MPa, and its limiting oxygen index is as high as 28.7, and the comprehensive performance of the system is the best. By testing the surface morphology of the flame retardant composites after combustion by SEM, it was found that a dense char layer was formed on the surface of the epoxy resin cured char residue and foamed obviously, indicating that the flame retardant curing performance of DOPO-AEP was good. [ABSTRACT FROM AUTHOR]

In this study, we address the challenge of hidden damages in FRP composites, such as delamination, matrix cracking, and fibre breakage resulting from transverse low-velocity impact (LVI)—damages often elusive on the surface. Our methodology operates at the meso-scale, depicting laminates as stacked homogenized plies incorporating interfaces. To capture the mechanical behaviour and damages, we extend an existing nonlinear mean-field debonding model (NMFDM), accommodating asymmetric matrix plasticity (AAMP), fibre–matrix interface debonding failure, and in-plane progressive failure. In a key enhancement, we introduce a strain rate term to the AAMP model, addressing strain rate effects associated with LVI loading. Additionally, we incorporate a novel strain-driven 3D failure criteria, offering a more precise assessment of progressive failure subjected to LVI loading. The interfaces between plies are modelled using surface-based cohesive behaviour to capture interaction phenomena. To validate the developed NMFDM, we conduct impact simulations at various energies on a UD composite laminate consisting of AS4/8552 carbon fibre and epoxy matrix. These simulations showcase the predictive capability and accuracy of the NMFDM in capturing the intricate behaviour and damage progression of UD composites subjected to LVI. [ABSTRACT FROM AUTHOR]

A three-dimensional viscoelastic-viscoplastic constitutive model is presented for predicting the dynamic mechanical behavior of an epoxy resin at low-to-medium strain rates. The model utilizes the generalized Maxwell model, incorporating two Maxwell elements in parallel with a nonlinear spring to represent the viscoelastic response at low and medium strain rates. By utilizing an empirical logarithmic relationship to predict the material properties at different strain rates, a nonlinear exponential relation based on overstress concepts is proposed for modeling the viscoplastic behavior. Comparing the tensile and shear stress–strain curves predicted by the proposed model with the experimentally measured curves, a good agreement is observed. Implementing the viscoelastic-viscoplastic model in commercial finite element software, a three-dimensional numerical discretization is performed. Through simulations of stress-relaxation and loading–unloading tests at various strain rates using the proposed material model, relaxation and hysteresis responses are analyzed. The model successfully predicts the experimentally measured hysteresis response of a specific epoxy resin during the loading cycle, consistent with other nonlinear viscoelastic models. This material model not only well replicates the nonlinear viscoelastic responses below the yield strain but also captures plastic nonlinearities at different strain rates. [ABSTRACT FROM AUTHOR]

Porous geopolymer composite (E51) reinforced by E51 epoxy resin was prepared by well‐distributed dual‐blending using red mud, metakaolin, and slag as raw materials. The effects of E51 content on microstructure, porosity, mechanical properties, and thermal insulation properties of the porous composites were investigated. The addition of E51 changed the setting time and viscosity of the slurry with high content of solid wastes (80%), which play an important role in the formation of pores during the direct foaming process. The addition of E51 had great influence on the porous properties of geopolymer composites, which in turn affected their compressive strength (0.19–1.44 MPa) and thermal conductivity (0.09–0.12 W/mK). The addition of E51 enabled the production of geopolymer composites in a rather large range of total porosity (67.3–81.1 vol%), with an optimal sample possessing a total porosity of up to 78.7 vol%, a thermal conductivity of 0.086 W/mK, and a compression strength of 0.47 MPa. [ABSTRACT FROM AUTHOR]

In recent years, ion-imprinted polymers have gained significant attention and are extensively utilized owing to their high selectivity toward target ions. For this research, Pb(II) ions were used as the template ions, polyamide-amine dendrimers as the curing agent, epoxy resin as the carrier and combined with ion-imprinting technique in the preparation of Pb(II)-imprinted polymer (Pb(II)-IIP). Systematic adsorption experiments were used to investigate the impact of the adsorbent on the adsorption performance of Pb(II) ions. The composition of the adsorbent was further studied by FT-IR, SEM and other characterization techniques. The maximal adsorption capacity at pH = 5 and T = 318 K was calculated to be 138.8 mg/g. In the coexistence of multiple ions, the Pb(II)-IIP showed high selectivity for Pb(II) adsorption. Pb(II) was still removed at a rate of more than 91% after five cycles of experiments, indicating good reusability. [ABSTRACT FROM AUTHOR]

Epoxy resin, characterized by prominent mechanical and electric‐insulation properties, is the preferred material for packaging power electronic devices. Unfortunately, the efficient recycling and reuse of epoxy materials with thermally cross‐linked molecular structures has become a daunting challenge. Here, we propose an economical and operable recycling strategy to regenerate waste epoxy resin into a high‐performance material. Different particle size of waste epoxy micro‐spheres (100–600 μm) with core‐shell structure is obtained through simple mechanical crushing and boron nitride surface treatment. By using smattering epoxy monomer as an adhesive, an eco‐friendly composite material with a "brick‐wall structure" can be formed. The continuous boron nitride pathway with efficient thermal conductivity endows eco‐friendly composite materials with a preeminent thermal conductivity of 3.71 W m−1 K−1 at a low content of 8.5 vol% h‐BN, superior to pure epoxy resin (0.21 W m−1 K−1). The composite, after secondary recycling and reuse, still maintains a thermal conductivity of 2.12 W m−1 K−1 and has mechanical and insulation properties comparable to the new epoxy resin (energy storage modulus of 2326.3 MPa and breakdown strength of 40.18 kV mm−1). This strategy expands the sustainable application prospects of thermosetting polymers, offering extremely high economic and environmental value. [ABSTRACT FROM AUTHOR]

Purpose: The study aims to ascertain the influence of solder conductive particle types and substrate widths on the current carrying capability of flex-on-board (FOB) assemblies. By comparing Sn58Bi and SAC305 particles and varying substrate widths, the research sought to provide insights into the stability and performance of solder joints under different scenarios, particularly in high-power applications. Design/methodology/approach: The study used a comprehensive design/methodology, encompassing the investigation of solder conductive particle types (Sn58Bi and SAC305) and substrate widths on the current carrying capability of FOB assembly. Stable solder joints were obtained by manipulating the curing speed of anisotropic conductive films for both particle types. Various tests were conducted, including current carrying capability assessments under differing conditions. Findings: The study revealed that larger substrate widths yielded higher current carrying capability due to increased contact area and reduced contact resistance. Notably, solder joints remained stable beyond the solder melting temperature due to encapsulation by cured epoxy resin. SAC305 solder joints exhibited superior current carrying capability over Sn58Bi in continuous high-voltage conditions. The results emphasized the stability of SAC305 solder joints and their suitability for robust interconnections in high-power FOB assemblies. Originality/value: This study contributes by offering a comprehensive assessment of the impact of solder particle types and substrate widths on solder joint performance in FOB assemblies. The finding that SAC305 joints outperform Sn58Bi under continuous high-voltage conditions adds significant value. Moreover, the observation of stable solder joints beyond solder melting temperature due to resin encapsulation introduces a novel aspect to solder joint reliability. These insights provide valuable guidance for designing robust and high-performance interconnections in demanding applications. [ABSTRACT FROM AUTHOR]

This work controlled the polymerization reaction, melting, and mixing processing of a mixture including epoxy resin and polyethylene glycol (PEG) by a pulverizer, to effectively develop high-performance shape memory epoxy/PEG (EPP) filaments. The process parameters of polymerization-melting-mixing-drawing were determined through the extrusion force investigation. The results showed that EPP mixtures could be developed into filaments through polymerization-melting-mixing-drawing process, reducing the spinning temperature and filament diameter from 300°C and 31 mm to 235°C and 13 mm, respectively. The Fourier transform infrared spectra confirmed the complete polymerization of epoxy resin and the stable existence of PEG. EPP filaments developed through the polymerization-melting-mixing-drawing process have exhibited controllable dynamic thermal mechanical properties and Tg, excellent shape recovery effects, and adjustable stimulus temperature. This work developed shape memory EPP filaments through a polymerization-melting-mixing-drawing process, with controllable spinnability and adjustable stimulus temperature, providing a reference for high-performance filament fabrication and process optimization. [ABSTRACT FROM AUTHOR]

In this work, pretreatment with vacuum ultraviolet (VUV) light changed the adhesion strength between an epoxy resin and directly sputtered copper in a printed circuit board manufacturing process. The adhesion strength was 0.9 N/cm without irradiation but had a peak value of 2.1 N/cm at 540 mJ/cm2 of VUV irradiation; with increasing VUV irradiation, the adhesion strength decreased. Based on x-ray photoelectron spectroscopy (XPS) analysis of the copper interface of copper peeled from the resin, we evaluated the abundance ratio of metallic and organic oxygen at interfaces exposed to different VUV irradiation doses. We found that the change in the abundance ratio of metallic and organic oxygen was similar to the change in adhesion strength between copper and epoxy resin after exposure to different VUV irradiation doses. We observed the interface between copper and resin via scanning transmission electron microscopy (STEM) and found a distributed layer of oxygen. The functional group concentration in STEM images suggested the presence of a material with an intermediate density. We used chemically modified XPS to evaluate changes in the functional group concentration on epoxy resin surfaces irradiated with VUV light. We found that the hydroxyl group (OH) formed by VUV irradiation and the copper formed by direct sputtering improved adhesion strength in a synergistic manner. We observed a correlation between OH concentration on the resin surface and adhesion strength. These results will help to optimize the VUV irradiation process for adhesion between epoxy resin and sputtered copper. [ABSTRACT FROM AUTHOR]

A tetrafunctional glycidyl ether cyclic siloxane epoxy resin (TGTS) has been synthesized, characterized and cured with four aromatic amine hardeners: 1,3‐phenylenediamine (PDA), diethyltoluenediamine (DETDA), 4,4‐diaminodiphenylmethane (DDM) and 1,3‐bis(4‐aminophenoxy)benzene (APB). Each of the cured networks produces transparent and homogeneous networks, although when TGTS is cured with DETDA, reduced compatibility led to lower epoxide consumption, a more heterogenous microstructure and deleterious effects upon properties. Reduced miscibility of DETDA significantly impacts the chemical structure and microstructure of the network, resulting in significant reductions in thermal and mechanical properties but higher UV‐A transmission. The PDA‐, APB‐ and DDM‐cured networks conversely were more miscible and display properties typical of organic–inorganic hybrid networks, such as good mechanical properties at ambient and sub‐ambient temperatures, comparatively high glass transition temperatures, improved resistance to oxidation and lower UV‐A transmission. © 2024 The Author(s). Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

With the wide application of epoxy resins in adhesives, electronic packaging materials, and aerospace fields, it is necessary to prepare high‐performance flame‐retardant epoxy resins to reduce the fire risk caused by their flammability. In this study, the rigid structure intermediate Schiff base (DMDA‐SH) was synthesized by condensation reaction of syringaldehyde (SH) with O‐Tolidine (DMDA). Then, DMDA‐SH‐DOPO, a novel P/N‐structured biobased flame‐retardant curing agent, was synthesized by addition reaction with 9,10‐dihydro‐9‐oxaza‐10‐phosphame‐10‐oxide (DOPO) and was applied to the preparation of intrinsic flame‐retardant epoxy resin. As expected, DMDA‐SH‐DOPO has good flame‐retardant properties due to the synergistic action of N/P elements. Epoxy resin with only 2.5% DMDA‐SH‐DOPO (P = 0.16%) can pass the UL‐94 V‐0 test. Compared with DGEBA/DDM, DMDA‐SH‐DOPO‐7.5's (P = 0.49%) peak heat release rate was reduced by 48.4% and the limiting oxygen index (LOI) reached 27%, making it a flame‐retardant material. From the point of view of carbonaceous residue performance, the expansion height of carbon residue after DMDA‐SH‐DOPO‐7.5 combustion is significantly increased, and the amount of carbon residue at 800°C is increased by 36.4%. In addition, appropriate DMDA‐SH‐DOPO can effectively improve the bending property of epoxy resin. This study provides a new idea for preparing renewable high‐performance intrinsic flame‐retardant epoxy resin. [ABSTRACT FROM AUTHOR]

Composite materials represent a cutting-edge formulation, combining two or more components to achieve multifunctional performance tailored for a range of multidisciplinary applications. In this study, it was focused on the fabrication of epoxy resin with glass fiber to produce a composite material. Furthermore, it explored the incorporation of carbon nanotubes (CNTs) into this formulation, paving the way for the development of self-healing composite sheets capable of withstanding bullet impacts. Characterization of the formulated composites involved a comprehensive comparative analysis utilizing attenuated total reflectance Fourier transform infrared spectroscopy (AT-FTIR) to assess chemical composition, alongside topographical studies employing scanning electron microscopy (SEM) and atomic force microscopy (AFM) to evaluate surface morphology as well as the thermal analysis study. Mechanical properties were rigorously analyzed using coherent gradient sensing (CGS) and mechanical testing methodologies. Our findings unveiled a remarkable compatibility between the epoxy resin and glass fibers in the presence of CNTs, indicating a synergistic enhancement in composite performance. Moreover, the remarkable self-healing capability post-bullet impact was substantiated through SEM imaging and advanced imaging techniques, affirming the efficacy of CNTs incorporation in bolstering composite resilience and durability. [ABSTRACT FROM AUTHOR]

Highlights In this paper, carboxyl‐terminated nitrile rubber (CTBN) and Nano cerium oxide (n‐CeO2) were used to toughen epoxy resin (EP), and the effects of toughening agents on the mechanical and thermal properties of EP were studied. Orthogonal experiments determined that the ideal toughener proportions are 20 wt% CTBN and 1 wt% n‐CeO2, under which the resin demonstrated superior mechanical characteristics. The combined application of CTBN and n‐CeO2 significantly enhanced the resin's mechanical properties, surpassing the effects of individual particle toughening. Compared with pure EP, the impact, flexural, and tensile strengths of the resin‐cured product synergistically toughened by CTBN and n‐CeO2 increased by 462%, 136%, and 110%, respectively, and the flexural and Young's moduli increased by 38% and 35%, respectively. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were used to characterize the cured resin. The results indicate that incorporating CTBN and n‐CeO2 reduces the reaction activation energy, thereby accelerating the curing reaction and facilitating its progression. The addition of nanoparticles enhances the maximum weight loss temperature of the cured resin, thereby improving its thermal stability. CTBN and n‐CeO2 particles create a uniform phase separation structure within the resin, enhancing its toughness and strength. Furthermore, the impact fracture mode of the cured resin transitions from brittle to tough fracture, demonstrating a significant toughening effect. This provides an effective method for the toughening modification of EP. The synergistic use of CTBN and n‐CeO2 enhances the toughness of EP. The incorporation of nanoparticles improves the thermal stability of the cured resin. The addition of CTBN and n‐CeO2 accelerates the curing reaction rate. The inclusion of toughening agents transforms the fracture mode of the cured resin from brittle to tough fracture. [ABSTRACT FROM AUTHOR]

Highlights To achieve the wave‐transparent and anti/de‐icing requirements of electromagnetic functional structural components on the windward surface of the aircraft, the PTFE capillary hot air tubes were pre‐buried inside the quartz fiber cloth and the hot air anti/de‐icing quartz fiber/PTFE capillary/epoxy resin (QF/PTFE/EP) composite components was prepared to that met the wave‐transparent performance. A multi‐field coupled numerical finite element simulation model was established, and the anti/de‐icing performance of the QF/PTFE/EP composite with different built‐in tube diameters were investigated by combining experiments and simulations under different hot air temperatures and pressures. The feasibility of hot air anti/de‐icing was verified through anti/de‐icing experiments and numerical simulation. The electromagnetic transmittance of the prepared hot air anti/de‐icing QF/PTFE/EP composite components was tested to characterize the effect on the stealth performance of the aircraft under the service environment. The experimental results demonstrated that with 5 mm tube pitch and hot air of 60°C ± 1°C, the surface temperature of the component with three tube diameters could reach more than 10°C. Furthermore, the decrease in the transmittance of the hot air anti/de‐icing QF/PTFE/EP composite components caused by different incidence angles and two polarization modes was less than 3%. The hot air QF/PTFE/EP anti/de‐icing composite components were fabricated. The heat transfer, anti/de‐icing, and electromagnetic transmittance performance of the hot air QF/PTFE/EP anti/de‐icing QF/PTFE/EP components were investigated. The experimental and simulation results verified the hot air anti/de‐icing QF/PTFE/EP components met the requirement of aircraft anti/de‐icing and wave transmission. [ABSTRACT FROM AUTHOR]

The capacity to withstand challenges posed by complex environments is crucial for developing advanced high‐performance protective materials with mechanically adjustable nature. By constructing long‐range hierarchical network of shear‐stiffening gel‐carbon nanotube‐cellulose nanofiber (SCC) embedded within epoxy resin (ER), this work engineers a nacre‐inspired variable‐stiffness SCC‐ER composite (SCCE). Lightweight SCC scaffold attenuates falling impact force from 2.23 to 0.46 kN, and reaches 60 °C within 20 s under 1 sun exposure. Additionally, owing to the rigid ER matrix, SCCE exhibits 4.03 GPa elastic modulus, outperforming numerous conventional engineering materials in puncture resistance. Specific energy absorption of nacre‐mimetic SCCE presents 1.91 MJ m−3 while that of random structural SCCE is only 0.50 MJ m−3. More importantly, SCCE features representative photothermal‐induced reversible rigidity whose storage modulus varies from 9.85 MPa at 30 °C to 11.61 kPa at 116 °C under light stimulation. It also presents shape‐programmability, capable of adhering complex structural surfaces for protection. Eventually, SCCE‐based semi‐active adjustable protectors are constructed that leverage contactless photothermal effect to modulate rigidity. 5 mm‐thick smart SCCE‐protectors resist 163.93 m s−1 ballistic impact while 15‐mm commercial kneepads are penetrated at lower speed of 136.98 m s−1. This bio‐inspired semi‐active strategy proposes a promising avenue for enhancing personal protective equipment. [ABSTRACT FROM AUTHOR]

In this article, to explore the utilization of bio‐based epoxy resin in the preparation of sizing agents for carbon fibers (CFs), a bio‐based epoxy emulsion (S‐P‐S) derived from spiro diacetal epoxy (SDE) resin was prepared and compared to the traditional diglycidyl ether of bisphenol A (DGEBA) based emulsion (D‐P‐D) and a mixed emulsion of S‐P‐S and D‐P‐D (S‐P‐S&D‐P‐D). The CF sized with S‐P‐S (CF‐(S‐P‐S)) showed improved surface oxygen content (22.86%) and roughness (40.9 nm), enhancing wettability and interfacial bonding between the fiber and the matrix. Nanoindentation test and AFM results showed the enhanced interfacial stiffness and a gradual modulus interphase with a thickness of 381 nm in CF‐(S‐P‐S) reinforced epoxy resin composite (CF‐(S‐P‐S)/EP). Therefore, the resulting CF‐(S‐P‐S)/EP composite possesses the best mechanical properties, with the transverse fiber bundle tensile (TFBT) strength of 27.3 ± 1.45 MPa and the interfacial shear strength (IFSS) of 85.6 ± 8.26 MPa. These results highlight the potential of the SDE‐based emulsion (S‐P‐S) to enhance the interfacial properties and mechanical performance of CF/EP composite, offering a sustainable alternative to conventional petroleum‐based epoxy resins. Highlights: Emulsion (S‐P‐S) was prepared using spiro diacetal epoxy (SDE) for carbon fiber sizing.Properties of S‐P‐S sized CF (CF‐(S‐P‐S)) and its composite were evaluated.Spiro diacetal structure created a gradual modulus interphase in CF‐(S‐P‐S)/EP.The interfacial properties of the CF‐(S‐P‐S)/EP composite were greatly improved.Bio‐based SDE resin showed promise for optimizing carbon fiber composite interphase. [ABSTRACT FROM AUTHOR]

The research on epoxy resin toughening is of great significance for its application in aerospace, automotive industries, marine vessels, and other fields. Poly‐ether‐ether‐ketone (PEEK) and carbon nanotubes (CNTs) are ideal candidates for epoxy reinforcement in thermoplastic materials and nanomaterials, respectively. In this study, CNTs were first chemically grafted onto PEEK microparticles using an amidation reaction. These modified hybrid materials were then utilized as fillers in epoxy composites to enhance their strength and toughness. The changes in sample structure, composition, thermal properties, and wettability during the chemical grafting process between CNTs and PEEK were systematically studied. In comparison to pure PEEK, the surface energy of CNTs‐PEEK hybrid materials increased by 11.58% due to CNTs grafting, resulting in improved wettability and enhanced interface bonding between PEEK and the epoxy matrix. Concurrently, the CNTs‐PEEK/epoxy composites exhibited significant enhancements, with the highest tensile strength, tensile elongation at break, flexural strength, and flexural modulus increased by 31.00%, 30.84%, 121.43%, and 23.22%, respectively. The positive reinforcement effect of modified CNTs‐PEEK fillers in epoxy composites and the exploration of CNTs grafting onto PEEK extend the potential applications of epoxy composites. Highlights: CNTs were bonded to PEEK via an amidation reaction by the chemical grafting method.CNTs‐PEEK have an 11.58% increase in surface energy compared to pure PEEK.CNTs‐PEEK/epoxy composites showed improved mechanical properties.The enhancement mechanisms of CNTs‐PEEK/epoxy composites were analyzed. [ABSTRACT FROM AUTHOR]

Reducing the fire risk of epoxy coatings has been a significant focus in the research of thermosetting resin materials. Various carbon nitride/polyaniline/metal oxide hybrids (CNPMOs) were synthesized using in‐situ oxidative polymerization and modified adsorption methods. Combustion analysis results indicated that CNPMOs effectively reduced the heat release of epoxy coatings during combustion. The epoxy coatings containing various CNPMOs (EFe, EY, and ETi) exhibited excellent smoke suppression and toxicity reduction properties. Furthermore, in comparison to the pure sample (E0) and reference sample (E1), the epoxy coatings EFe, EY, and ETi demonstrated improved thermal stability. In water resistance tests, the water absorption rates of EFe, EY, and ETi were significantly lower than that of E0. The CNPMOs enhanced the hydrophobicity of the epoxy coating to better protect the substrate in humid environments. [ABSTRACT FROM AUTHOR]

AbstractBisphenol A (BPA), a synthetic chemical widely used in the production of polycarbonate plastic and epoxy resins, has been associated with a variety of adverse effects in humans including metabolic, immunological, reproductive, and neurodevelopmental effects, raising concern about its health impact. In the EU, it has been classified as toxic to reproduction and as an endocrine disruptor and was thus included in the candidate list of substances of very high concern (SVHC). On this basis, its use has been banned or restricted in some products. As a consequence, industries turned to bisphenol alternatives, such as bisphenol S (BPS) and bisphenol F (BPF), which are now found in various consumer products, as well as in human matrices at a global scale. However, due to their toxicity, these two bisphenols are in the process of being regulated. Other BPA alternatives, whose potential toxicity remains largely unknown due to a knowledge gap, have also started to be used in manufacturing processes. The gradual restriction of the use of BPA underscores the importance of understanding the potential risks associated with its alternatives to avoid regrettable substitutions. This review aims to summarize the current knowledge on the potential hazards related to BPA alternatives prioritized by European Regulatory Agencies based on their regulatory relevance and selected to be studied under the European Partnership for the Assessment of Risks from Chemicals (PARC): BPE, BPAP, BPP, BPZ, BPS-MAE, and TCBPA. The focus is on data related to toxicokinetic, endocrine disruption, immunotoxicity, developmental neurotoxicity, and genotoxicity/carcinogenicity, which were considered the most relevant endpoints to assess the hazard related to those substances. The goal here is to identify the data gaps in BPA alternatives toxicology and hence formulate the future directions that will be taken in the frame of the PARC project, which seeks also to enhance chemical risk assessment methodologies using new approach methodologies (NAMs). [ABSTRACT FROM AUTHOR]

Aim: To investigate the effects of Epigallocatechin gallate (EGCG) and curcumin, as a final irrigant on the fracture resistance of irradiated root that obturated with an epoxy resin sealer. Methodology: Eighty mandibular premolars were randomly divided into non-irradiated (NIR) and irradiated (IR) groups. The teeth were irradiated at 2 Gy per fraction, 5 times a week for a total dose of 60 Gy over 6 weeks. All specimens were decoronated, remaining 13±1 mm root length. Two groups were subdivided into four groups (n = 10): 1) non-instrumented; the intact root served as control. The other roots were instrumented with a pro-taper NiTi rotary system. The final irrigation used was 17% EDTA, followed by three irrigation solution groups; 2) 2.5% NaOCl, 3) 0.02% EGCG, and 4) 0.1% curcumin. Root canals were filled with gutta-percha and AH plus. All specimens were embedded in self-curing acrylic resin and loaded vertically at 1 mm/min until fracture occurred. Also, sealer penetration was assessed by confocal laser scanning microscopy (CLSM). The data were evaluated statistically using two-way ANOVA and Tukey test (α = 0.05). Results: In irradiated roots, fracture resistance of EGCG and curcumin groups did not differ from non-instrumented roots, but they were higher than the NaOCl group (P = 0.006). However, NaOCl, EGCG, and curcumin in irradiated roots had comparable strength that was higher than in the non-instrumented group (p<0.001). Difference between irradiated and non-irradiated roots was observed only for NaOCl and non-instrumented groups (P≤0.004). In irradiated roots, a higher sealer penetration was observed in EGCG and curcumin groups compared to NaOCl. Conclusion: EGCG and curcumin could be promising final irrigants to reverse the adverse effect of radiotherapy on the strength of irradiated roots obturated with AH Plus sealer. [ABSTRACT FROM AUTHOR]

Highlights The development of epoxy resin (EP) potting material with high thermal conductivity (TC) and excellent electrical insulating properties plays an important role in the development of drive motors to high specific power and high voltage. In this study, a simple preparation method is presented to solve the problem of low content filler settling and low TC of EP. Firstly, small‐sized perfluoroalkyltrimethoxysilane surface‐treated nanodiamond (ND) and large‐sized hydroxylated boron nitride (BN) were adsorbed together using hydrogen bonding to construct “Sesame Cookie”‐like structures. The heterostructure filler with different “sesame” contents were obtained by modulating the ND:BN ratio, and were filled into high‐temperature resistant AG70 EP at a fixed mass ratio of 20 wt.%. By surface treatment, the dispersibility of fillers in EP was improved, and the settling problem of low content fillers was solved. Finally, when the ratio of ND: BN is 1:2, the TC value of EP composite reached 0.94 W·m−1·K−1, which was 348% higher than pure EP, and the composite possessed good electrical insulating properties. In addition, the heat‐resistance temperature of the composite exceeded 200°C, which ensured the stable operation of the drive motor. This study presents new ideas for the exploitation of EP potting materials with high TC and excellent electrical insulating properties. Heterostructure filler is constructed using hydrogen bonding. Dispersion of the filler in the EP is improved by surface treatment. The TC value of the EP composite increased by 348%. The heat‐resistant temperature of the EP composite is more than 200°C. The EP composite has excellent insulating properties. [ABSTRACT FROM AUTHOR]

Highlights The waste carbon fiber reinforced epoxy (WFRE) is difficult to recycle and high‐value reuse due to its irreversible cross‐linked structure. Currently, many recycling methods are flawed, rendering effective recycling unattainable and resulting in the waste of high‐value carbon fibers and increased environmental pollution. In this study, the production of high‐aspect‐ratio carbon fiber powder from WFRE was achieved through the application of solid‐state shear milling technology. The prepared EP/WFRE/CNT composites exhibited commendable mechanical properties and good electromagnetic interference (EMI SE) shielding efficiency, owing to the excellent dispersion and interfacial adhesion. The EMI SE value of EP/WFRE/CNT composites reached 21.9 dB, meeting the basic demand in the civil field. The flexural modulus of EP/WFRE/CNT composites reached 5914 MPa with the incorporation of 5 wt.% CNT. Moreover, the storage modulus of composite at 40°C increased from 2299 MPa for neat epoxy to 3006 MPa for composites. This research proposes a novel application of WFRE as good mechanical performance material for electromagnetic interference shielding, demonstrating the potential for commercial‐scale applications. Solid‐state shear milling can effectively peel epoxy resin. Solid‐state shear milling can preserve the high aspect ratio of carbon fiber. EP/WFRE/CNT has a flexural modulus of up to 5914.8 MPa. EP/WFRE/CNT has EMI SE that reaches 21.9 dB. CNT and carbon fiber synergistically formed conductive network. [ABSTRACT FROM AUTHOR]

Highlights The demand for epoxy (EP) in semiconductor, aerospace, and other applications is currently on the rise. However, pure epoxy is difficult to meet these requirements, such as low thermal conductivity and poor toughness. Therefore, in this paper, sulfonamides (SAs) and core‐shell silica (SLC‐SiO2) were grafted onto the surface of short carbon fibers (SCF) with sizes of 0.1–6 mm by the chemical grafting method. As a result, the surface activity of SCF was improved and the interfacial properties of the EP composites were enhanced. The interfacial compatibility of SCF grafted with SAs and SLC‐SiO2 in EP is greatly improved, resulting in stronger mechanical interlocking and chemical bonding ability between EP and SCF. The results showed that when the content of SCF@SAs@SLC‐SiO2/EP composites reached 0.3 wt% of SCF@SAs@SLC‐SiO2, the impact and tensile strengths were increased from 12.15 kJ·m−2 and 43.4 MPa to 16.93 kJ·m−2 and 74.97 MPa compared with the pure epoxy, which were improved 39.3% and 72.7%. In addition, the thermal conductivity of SCF@SAs@SLC‐SiO2/EP composites was also improved by 12.5% from 0.205 W·(m·K)−1 to 0.2306 W·(m·K)−1 compared with the pure EP. This is due to improved chemical interactions and mechanical interlocking at the fiber‐epoxy interface. This study provides a new method for the preparation of high‐performance SCF/EP composites. The amino group of sulfonamides was grafted with short carbon fiber to increase the surface active group of short carbon fiber. Sulfonamides react with carboxyl groups on the surface of core‐shell silica to form an “organic–inorganic” structure. Improve the surface roughness of short carbon fiber, and make it evenly dispersed in epoxy resin, so as to improve the performance of epoxy composite materials. [ABSTRACT FROM AUTHOR]

Highlights Excited by the effect of amphiphilic block copolymer Polyethylene glycol‐b‐Polypropylene Glycol‐b‐Polyethylene Glycol, a triblock copolymer (TBCP) in the virgin state as well as in the grafted form with graphene oxide and multiwalled carbon nanotube in epoxy toughening, the effect of the same block copolymer in the exfoliation of graphene analogous Transition Metal Dichalcogenides (TMDs) was studied. Even though epoxy resin has several advantages, its inherent brittleness and flammability limit its application in several areas. So, there is a need for the efficient toughening of epoxy resin to make it appropriate for high‐end applications. In the present work, epoxy resin was toughened with exfoliated TMDs, especially Molybdenum sulfide and Tungsten disulfide (MoS2 and WS2). TBCP was used in the exfoliation of TMDs where the effect of these exfoliated TMDs in enhancing the properties of epoxy was evaluated. TBCP exfoliated MoS2 and WS2 exhibit fracture toughness of 483% and 636%, respectively in epoxy composites without compromising the tensile properties, which enhances the efficacy of epoxy resins towards high‐end applications. The improvement in toughness is evident from the fractography of the crack surfaces. The role of TBCP exfoliated TMDs in tuning the mechanical, thermal, and thermomechanical properties is portrayed in the manuscript, thereby unveiling the potential of yet another unique class of materials in epoxy toughening. The efficiency of amphiphilic block copolymer in exfoliating TMDs is analyzed. The effect of TBCP‐exfoliated TMDs as a toughener for the epoxy matrix is portrayed. 483% and 636% improvement in the toughness compared to neat epoxy was obtained for TBCP exfoliated MoS2 and WS2 reinforced epoxy respectively. Improved tensile properties after incorporation of TBCP exfoliated TMDs in epoxy matrix. The plasticizing effect of TBCP compromises the thermal properties. [ABSTRACT FROM AUTHOR]

In this study, the shear strength and thermal properties of the adhesively bonded joints were investigated of adhesives reinforced with nanoparticles using carbon fiber-reinforced composite materials. The diglycidyl ether bisphenol A (DGEBA) was used as the epoxy resin. Single lap joint tests of 1% wt. Multi-walled carbon nanotubes (MWCNT) and 3, 5, and 7% wt. silicon dioxide (SiO2) nanoparticle-reinforced mixed adhesives were performed according to ASTM D5868 standards. The shear strengths of the mixed adhesives obtained by mixing at different ratios were compared with the epoxy resin. Upon conducting an analysis of the shear strengths of nanomaterials, results indicate that the incorporation of 1CNT + 3SiO2 in the nanomaterials showed the greatest improvement, with a 46% increase in shear strength. 1CNT + 5SiO2, 1CNT, and 1CNT + 7SiO2 showed increases of 32%, 14%, and 5%, respectively. The results of a tensile test indicate that pure epoxy exhibited a tensile strength of 5953 N, 1CNT, and 3SiO2, while the epoxy composite demonstrated a significantly higher tensile strength of 8738 N, along with an elongation of 0.72 mm. In addition, the morphology of fractured surfaces was examined by scanning electron microscopy (SEM). To investigate damage mechanisms, such as bridging, crack blunting, and branching of nanoparticles were observed. Characterization of epoxy resin and mixed MWCNT + SiO2 nanoparticles reinforced adhesives were also performed using Fourier infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). Nanoparticles are settled between polymer chains, improving polymer chains' motion and thermal properties. [ABSTRACT FROM AUTHOR]

Carbon fiber (CF)‐reinforced epoxy resin (EP) composites are lightweight materials with excellent comprehensive performance. However, the flammability of EP and the poor interfacial bonding between CF and EP are two key disadvantages that limit their further applications. Here, a kind of water‐soluble lignin‐based CF sizing agent (ELBEDK) is prepared through hydrophilic modification of enzymatic lignin, which can significantly enhance the interfacial interaction between CF and EP. Additionally, a highly efficient intumescent flame retardant (LMA) is prepared. The EP, enzymatic lignin, LMA and CF sized ELBEDK are compounded to obtain the fire‐safety CF reinforced composites (SCF/FEP/L). The flame retardancy of SCF/FEP/L with 7% LMA (SCF/FEP7) reached V‐0 rating. Moreover, SCF/FEP/L with 7% LMA and 15% lignin (SCF/FEP7/L15) present an limiting oxygen index (LOI)of 30.2% and V‐0 of UL‐94. Specifically, the total smoke production and the heat release rate are 47.8% and 46.81% lower than that of SCF/EP, respectively, indicating the improved smoke suppression and flame retardancy. The IFSS and flexural strength of SCF/FEP7/L15 are improved to be 59.4 MPa and 511.1 MPa, respectively. This study presents a simple approach to fabricate low‐cost high performance lignin‐based flame retardant CF/EP biocomposites with wide application potential. [ABSTRACT FROM AUTHOR]

Epoxy resins, ubiquitous and indispensable thermosetting material in various industries, suffer from the resistance to crack initiation, poor ductility, and irreparable permanent cross‐linked network, which hinder their utilization in high‐performance applications and are detrimental to the development of a sustainable economy. However, achieving the trade‐off between toughness, robustness, and reprocessability of epoxy resins remains a formidable challenge. Herein, an epoxy resin that combines ultratoughness, robustness, and reprocessability by incorporating a hierarchical crosslink structure embedded in a transesterification network is reported. The construction of hierarchical coordination structures facilitates formation of dense nano‐hard domains, enabling enhancement of both strength and toughness at multilength scales. As a result, the epoxy resin, integrating covalent adaptable networks with sacrificial non‐covalent networks, exhibits exceptional elongation at break (280%), modulus (1.8 GPa), stress at break (56.3 MPa), and tensile toughness (142 MJ m−3), showcasing its excellent endurance and ability to undergo multiple reprocessability. The application of this epoxy resin in carbon fiber‐reinforced polymer composites further underscores its potential as the resulting HCEV‐CFRPs exhibit unprecedented tensile properties and facilitate multiple non‐destructive recycling of high‐value carbon fiber under mild conditions. This research provides novel design principles for recyclable and high‐performance materials that combine strength and toughness. [ABSTRACT FROM AUTHOR]