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One of the main issues in epoxy‐based composite manufacturing is the formation of porosity derived from moisture absorption during storage and layup due to the high hydrophilicity of epoxy matrices. During the curing process, the presence of moisture and other volatile compounds can initiate the nucleation and growth of voids. In this study, the effect of both the initial water content absorbed in the uncured resin and the pressure on the porosity development in an epoxy resin was investigated. In particular, Kardos' and Ledru's models, aimed at predicting void formation in polymers, were applied to study the effect of different hydrostatic pressures in an epoxy resin during curing up to the gel point, after conditioning it at two different relative humidity levels, 50% and 95%. Subsequently, the porosity of the cured resin samples was quantified through density measurements. Comparative analysis of the microscopy images of cured samples and the predictions of both models revealed an overestimation of the final void sizes by both models, with the Kardos' model exhibiting a higher deviation. Additionally, a finite element model was employed to investigate the conditions leading to void formation, aiming to understand the factors influencing the porosity development and properly set the process parameters during composite manufacturing. Highlights: Evaluation of the conditions leading to void growth in epoxy resin during curingMoisture sorption in uncured epoxy resinEffect of curing pressure on pore developmentFinite element analysis for void growth during resin curing [ABSTRACT FROM AUTHOR]

Aramid fiber‐reinforced epoxy resin composites (AFRP) are the main components of electrical equipment such as GIS insulated tie rods, but the poor interfacial bonding between aramid fibers (AF) and epoxy resin (EP) results in a degradation of the material's insulating properties. In this paper, iron phthalocyanine (FePc) molecules are introduced on the AF surface, and the π‐π interaction effect between the metal phthalocyanine rings is used as a driving force to guide the spontaneous assembly of FePc into a three‐dimensional microstructure, and the effect of microstructures with different FePc contents on the insulating properties of AFRP interfaces is investigated. Combining a series of test simulation methods such as surface potential attenuation test, electric tree test, interlayer shear test, and molecular dynamics simulation, reveals the enhancement mechanism of the electrical insulation performance of the interface. The results show that FePc at four contents has an enhancement effect on the flashover voltage along the AF and the breakdown voltage at the AFRP interface, with a maximum enhancement of 25.63% for the flashover voltage and 232.23% for the breakdown voltage. Highlights: Self‐assembled three‐dimensional structures on aramid surfaces were constructed via iron phthalocyanine molecules.The effects of self‐assembled structures on physicochemical properties are compared.Modifications substantially increase the breakdown voltage and flashover voltage.The mechanism of microstructure on interface breakdown voltage enhancement is revealed.The overall effect of multiple factors on insulation properties is analyzed. [ABSTRACT FROM AUTHOR]

The homogeneous dispersion of multi‐walled carbon nanotubes (MWCNTs) in a polymer matrix significantly affects the overall properties of composites. In this study, MWCNTs/epoxy (EP) composites were prepared using DeoxyriboNucleic acid (DNA) as a dispersant. The MWCNTs were uniformly dispersed in a phenalkamine curing agent and crosslinked with an epoxy resin matrix. The non‐covalent functionalization of DNA‐dispersed MWCNTs was confirmed by characterizing both the pristine and DNA‐modified MWCNTs. Additionally, the dispersion state and stability of MWCNTs in the curing agent solution were evaluated. Tensile strength and single‐lap‐shear (SLS) were employed to assess the mechanical properties of the composites. The results indicated that the DNA‐dispersed MWCNTs composites exhibited superior strength and toughness, with tensile and shear strengths of 46.81 and 19.64 MPa, respectively, at optimal ratios. These values represent increases of 68.38% and 50.96% compared to pure EP. Dynamic mechanical thermal analysis (DMTA) revealed that the energy storage modulus of DNA‐dispersed MWCNTs/EP composites increased to 2722 MPa, a 24.7% enhancement over pure EP. Furthermore, the thermal properties of the composites were thoroughly investigated. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) showed that the initial decomposition temperature of the DNA‐assisted dispersed composites rose to 330°C. The macromolecular relaxation of the EP materials occurred at higher temperatures, leading to an increased glass transition temperature. Highlights: DNA was used to disperse MWCNTs in phenalkamine curing agent.MWCNTs/EP composites were made by crosslinking DNA‐dispersed MWCNTs with epoxy resin.DNA‐dispersed MWCNTs boosted tensile and lap shear strength.Thermal properties improved due to DNA‐dispersed MWCNTs, and increased the energy storage modulus of the composite. [ABSTRACT FROM AUTHOR]

In this study, interleaving electrospun Nylon 6.6 nanofibers in the laminate was utilized to improve interlaminar properties of glass/epoxy composite during punching and as a solution to this issue. In order to do so, virgin and nano modified samples are produced and punched and the results are compared to determine the effect of nanofibers on the damaged area as well as the three‐point bending residual strength (carried out on both penetration and exit sides) of the punched laminate. Furthermore, punch—die clearance was also varied to investigate the range in which the nano modification improves the outcome of the process on the laminated composite. According to results of this study, using of Nylon 6.6 nanofibers between composite layers causes significant decrease in the damaged area up to 50%. Also, in both virgin and nano modified laminates, increasing the punch—die clearance increases the damaged area up to 50% and reduces the residual strength of the laminates up to 17%. In addition, nano modified laminates, the residual strength increased up to 28% and 22% for three‐point bending tests carried out on both punch penetration‐ and exit‐side samples, respectively. This is due to the fact that the punch exit‐side contains more damage compared to the penetration‐side. Highlights: Toughening glass/epoxy laminates using electrospoon Nylon 6.6 nanofibers.Decreasing the damage area occur in the punching of composite laminates.Decreasing the damage area in punching by decreasing the punch‐die clearance.Increasing the strength of punched laminates by applying nanofibers. [ABSTRACT FROM AUTHOR]

This study presents a comparative analysis of carbon fiber reinforced polymer (CFRP) composites manufactured through vacuum assisted resin infusion (VARI) using a traditional epoxy resin (E), a fully‐recyclable epoxy resin system with (BBR10) and without (BBR) the addition of a reactive diluent (R*Diluent). Various mechanical and thermal tests were conducted to assess their performance. The BBR10 laminate, incorporating 10 wt% R*Diluent, exhibited competitive mechanical performance, comparable to traditional (E) and fully‐recyclable laminates (BBR). Despite a slightly lower ultimate tensile strength (UTS) compared with BBR, BBR10 demonstrated improved flexural strength and modulus. Low‐velocity impact testing confirmed comparable strength between VARI‐produced composites with the recyclable matrix (BBR and BBR10) and the traditional one (E). X‐ray mCT investigations revealed distinct void arrangements in the CFRP laminates. Additionally, a chemical approach was employed for recovering high fractions of fibers from CFRP laminates with a recyclable matrix (BBR and BBR10). Chemical recycling achieved an almost 100% yield for long carbon fibers. Highlights: Comparative analysis of CFRP composites manufactured through VARI.Diluent addition allowed to tailor the recyclable epoxy viscosity.Mechanical characterization of traditional and fully recyclable epoxy resins.Investigation by X‐ray mCT of potential flaws and manufacturing defects.Chemical recycling of CFRP laminates with a recyclable matrix. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study of the fabrication and joining mechanisms of carbon fiber reinforced polymer (CFRP) composites. The CFRP composites were fabricated by hand lay‐up and vacuum bagging methods. In order to improve the efficiency of the CFRP‐CFRP and CFRP‐AL 7075‐T651 joints, laminates with varying overlap lengths of 25 and 60 mm single lap joints were prepared in both multi‐riveted and hybrid bonded/riveted joint configurations. Due to the epoxy compatibility of CFRP‐CFRP joints, riveted/bonded hybrid joints (HJs) showed superior improvements compared to riveted joints for both material combinations at 25 and 60 mm overlap lengths. Non‐epoxy compatible surfaces of CFRP‐AL 7075‐T651 specimens performed similarly to riveted joints in hybrid configurations. The use of epoxy compatible surfaces was found to increase the joint strength in CFRP‐CFRP single lap hybrid joints in proportion to the increase in overlap length. Ansys non‐linear analysis and experimental results were complementary. The new improvements in joint efficiency of CFRP composites create a wide range of structural applications considering the increasing lifetime of the components and joints. Highlights: Riveting of composites have negative impact on joint strentgh.Hybrid joints using a combination of rivets and adhesives can increase the load bearing capacity.Tensile performance strategy of joint in composites can be improved by diversification of joint combinations. [ABSTRACT FROM AUTHOR]

The interface property of carbon fiber/matrix materials is a key factor influencing the service life of composites. In this paper, our group facilely in‐situ grew zeolitic imidazolate framework‐8 (ZIF‐8) onto the carbon fiber (CF) surface by using branched polyethyleneimine (BPEI) as coupling agent to simultaneously enhance the interface and mechanical performances of CF/epoxy composite. The successful growth of ZIF‐8 nanocrystals onto carbon fiber was confirmed by FT‐IR, XPS, TGA, XRD, Raman, and SEM. After growth of ZIF‐8, the surface morphology for CF grafted with ZIF‐8 (CF‐ZIF‐8) was greatly changed and the surface energy for modified carbon fiber increased from 28.7 mN/m for the untreated CF to 55.8 mN/m. As a result, the interfacial shear strength (IFSS) of CF‐ZIF‐8/epoxy composite enhanced by 103.4%, indicating a significant improvement of interface property of composite. Moreover, the interlaminar shear strength (ILSS) and bending strength also have 37.8% and 23.3% improvement because of the synergistic effect of BPEI and ZIF‐8 compared to the untreated CF/epoxy composite. This work furnishes a facile and efficient strategy for developing high‐performing structural composite materials with excellent interface property. Highlights: ZIF‐8 was in‐situ grown on CF to improve the interface property of composite.Significant improvements on IFSS, ILSS, and bending strength.The mechanism for improving the performances of composite was proposed. [ABSTRACT FROM AUTHOR]

This study explores the development of nanocomposites by incorporating multi‐walled carbon nanotubes (MWCNT), titanium nitride (TiN), and cubic boron nitride (c‐BN) nano powders into photo‐polymer epoxy resins for use in Stereolithography (SLA) additive manufacturing. Mechanical and thermal properties were systematically investigated to assess their performance. Initially, MWCNT, TiN, and c‐BN nano powders were homogeneously mixed with the resin to ensure uniformity. The resulting mixtures were then processed using SLA technology to evaluate production quality and material performance. The study revealed significant improvements in mechanical and thermal properties compared to pure resin, aligning with previous research outcomes. Specifically, the incorporation of MWCNT led to a notable enhancement in thermal conductivity, showing an increase of 24.21% as the thermal conductivity coefficient increased from 0.19 to 2.36 W/m·k. On the other hand, c‐BN significantly boosted mechanical strength, resulting in a substantial 20.45% increase as the shore D hardness went from 88.53 to 106.64. These findings highlight the promising potential of nanocomposites across various industries including electronics, aerospace, automotive, construction, medical devices, and manufacturing. Highlights: Developed nanocomposites with MWCNT, TiN, and c‐BN in SLA resin.c‐BN increased hardness by 20.45%, proving its effectiveness in composites.MWCNT enhanced thermal conductivity by 24.21%, boosting material performance.Pioneering use of TiN and c‐BN in SLA, addressing gaps in existing research.Applications span electronics, aerospace, automotive and medical devices. [ABSTRACT FROM AUTHOR]

Supercritical CO2 (sc‐CO2) was widely used in CO2 flooding projects to enhance the recovery efficiency recently owing to its amazing dissolving capability and permeability. Fiber reinforced pipe (FRP) has exceptional properties that may be widely used in the petrochemical sector for transportation of corrosive fluid in CO2 flooding projects. In this research, a system was designed to simulate the transport behavior of fluids containing CO2 which can reaches the supercritical state by the adjustment of pressure and temperature. The fluid penetrates into the resin interior through the pores and gathers in the cavities at 65°C and 8 MPa. When the temperature and pressure are below the critical point, the CO2 volume expands dramatically, causing inter‐layered micro‐crack. When the environmental conditions repeatedly change above and below the critical point, these cracks will continue to propagate along the fiber arrangement direction, resulting in the fracture progressively grow into the delamination. At the same time, the fluid corrodes the resin in some areas of the surface, generating pitting and a 0.66% loss in resin content. The composition of elements and groups altered after corrosion revealed that a chemical interaction occurred between fluid and epoxy resin. Finally, due to physical and chemical processes produced by penetration, expansion, and dissolution, the stiffness of FRP fell by 3.53% during treatment. Highlights: In the present work, a reactor coated with polytetrafluoroethylene (PTFE) was built to model the corrosion of FRP in delivery fluids containing sc‐CO2. The corrosion mechanism was shown as a combination action by chemical react and physical behavior comprising penetration, expansion and dissolution.The physical corrosion mechanism of fluid containing sc‐CO2 was investigated. The fluid containing sc‐CO2 penetrated the FRP via pores and accumulated in cavities. The quick expansion of sc‐CO2 causes delamination while the ambient circumstances remain below the critical threshold. The pitting and resin loss can be linked to the epoxy resin solution in supercritical CO2.The chemical process, known as hydrolysis, took place on the interior surface of epoxy resin and a fluid containing supercritical CO2. This finally resulted in molecular structural modification. [ABSTRACT FROM AUTHOR]

Supercritical CO2 (sc‐CO2) was widely used in CO2 flooding projects to enhance the recovery efficiency recently owing to its amazing dissolving capability and permeability. Fiber reinforced pipe (FRP) has exceptional properties that may be widely used in the petrochemical sector for transportation of corrosive fluid in CO2 flooding projects. In this research, a system was designed to simulate the transport behavior of fluids containing CO2 which can reaches the supercritical state by the adjustment of pressure and temperature. The fluid penetrates into the resin interior through the pores and gathers in the cavities at 65°C and 8 MPa. When the temperature and pressure are below the critical point, the CO2 volume expands dramatically, causing inter‐layered micro‐crack. When the environmental conditions repeatedly change above and below the critical point, these cracks will continue to propagate along the fiber arrangement direction, resulting in the fracture progressively grow into the delamination. At the same time, the fluid corrodes the resin in some areas of the surface, generating pitting and a 0.66% loss in resin content. The composition of elements and groups altered after corrosion revealed that a chemical interaction occurred between fluid and epoxy resin. Finally, due to physical and chemical processes produced by penetration, expansion, and dissolution, the stiffness of FRP fell by 3.53% during treatment. Highlights: In the present work, a reactor coated with polytetrafluoroethylene (PTFE) was built to model the corrosion of FRP in delivery fluids containing sc‐CO2. The corrosion mechanism was shown as a combination action by chemical react and physical behavior comprising penetration, expansion and dissolution.The physical corrosion mechanism of fluid containing sc‐CO2 was investigated. The fluid containing sc‐CO2 penetrated the FRP via pores and accumulated in cavities. The quick expansion of sc‐CO2 causes delamination while the ambient circumstances remain below the critical threshold. The pitting and resin loss can be linked to the epoxy resin solution in supercritical CO2.The chemical process, known as hydrolysis, took place on the interior surface of epoxy resin and a fluid containing supercritical CO2. This finally resulted in molecular structural modification. [ABSTRACT FROM AUTHOR]

Highlights Hybrid fiber‐reinforced composites uniquely address the performance limitations of carbon fiber‐reinforced polymers (CFRPs). In this study, continuously wrapping large tow CF (48 K) with low‐cost nylon was proposed to create nylon‐CF core‐spun yarns (NCCYs). Unidirectional nylon‐CF/epoxy composites (NCFECs) were successfully fabricated using NCCYs as hybrid fiber reinforcement. The nylon wrapping on the CF significantly enhanced the energy absorption and dispersion of the CFRPs, thereby improving the impact strength. The measured impact strength of the NCFECs was 108.7 kJ/m2, which was 70.4% greater than that of the corresponding CF/epoxy composite (63.8 kJ/m2) with the same CF content. Additionally, NCCYs exhibited an excellent interfacial shear strength of 35.3 MPa, representing a 73.9% increase compared to that of the large tow CF (20.3 MPa). This study developed NCFECs using a simple and low‐cost process to produce advanced composites, providing an innovative manufacturing strategy for CFRPs with high impact resistance. The NCCYs are prepared by using the wrapping technology. The structure of the wrapped yarns endows the NCCYs with high interfacial shear. The nylon fiber layer gives NCFECs higher impact strength. [ABSTRACT FROM AUTHOR]

Highlights SiO2 and Al2O3 micron particle effects on the mechanical and vibration properties of carbon fiber‐reinforced polymer (CFRP) composites were systematically investigated by incorporating these particles into the epoxy resin. CFRP laminates were prepared by adding various weight fractions (0–10 wt. %) of micron particles to the epoxy resin. The influence of cutout shape and the angle (θcf) between square cutout and fiber orientation on the vibrational performance of CFRP laminates were investigated. As the particle weight fraction (PWF) increased, the tensile, bending, interlaminar shear, and vibration properties of CFRP initially improved and then declined. The flexure strength of samples with 4 wt. % SiO2 and Al2O3 particles increased by 11.70%. The samples with 8 wt. % SiO2 and Al2O3 particles exhibited the highest damping ratio, which was 4.59 times greater than that of the samples without particles. The cutout shape and θcf influence the vibration performance of CFRP laminates. For the rectangular cutout, the sample with θcf = 22.5° exhibits the highest damping ratio, exceeding those at 0° and 45° by 2.28% and 7.10%, respectively. Three‐roll milling can disperse 4 wt.% particles in resin. SiO₂ and Al₂O₃ particles improve mechanical properties of CFRP. SiO2 and Al2O3 particles increased the damping ratio of CFRP by 359.22%. Circular cutout minimally reduces the first‐order natural frequency of CFRP. Angle between rectangular cutout and fiber affects CFRP vibrational properties. [ABSTRACT FROM AUTHOR]

Highlights Ultrasonic methods are more sensitive to defects such as voids, pores, and discontinuities that can diminish the true elastic and acoustic properties of materials compared to destructive testing. Therefore, the elastic properties and some acoustic properties of the epoxy phenol novolac modified with polystyrene (EPN‐PS) matrix‐based nano‐ and hybrid composites were determined for the first time using ultrasonic method. Montmorillonite‐type nanoclay (NC) and industrial red mud waste (RMW) at a rate of 1–4 and 15–35 wt% respectively, were used as fillers in the composite preparation. According to the results, the highest elastic coefficient values (L = 8.14 GPa, G = 1.76 GPa, K = 5.79 GPa and E = 4.80 GPa) were obtained in the EPN‐PS/NC1 (with 1 wt% NC) nanocomposite sample compared to the elastic properties of pure EPN and EPN‐PS, while the highest elastic coefficient values (L = 8.97 GPa, G = 2.19 GPa, K = 6.06 GPa, and E = 5.86 GPa) among hybrid composites (HC) were obtained for the HC35 containing 2 wt. % NC and 35 wt% RMW. Due to both its high elastic and good acoustic properties, wall panels and floors produced using HC35 hybrid composite can be used for sound insulation in noisy environments. First evaluation of the acoustic characteristics of epoxy phenol novolac modified with polystyrene‐nanoclay/red mud waste (EPN‐PS‐NC/RMW) composites. NC4 with 4 wt% nanoclay showed the lowest elastic and acoustic properties. Nanoclay ratio above 1 wt% reduces elastic and acoustic properties. The increasing RMW ratio in hybrid composites increases elastic properties. High elastic and acoustic properties make HC35 ideal for sound insulation. [ABSTRACT FROM AUTHOR]

Highlights This study explores the enhancement of electromagnetic interference (EMI) shielding effectiveness (SE) in carbon fiber‐reinforced polymer (CFRP) composites through the integration of equatomic CoCuFeNi high entropy alloy (HEA) particles. Employing mechanical alloying (MA), CoCuFeNi HEA powders were synthesized, revealing a face‐centered cubic structure with crystallite and particle sizes of 14.7 nm and 11.62 μm, respectively. The integration of these HEA particles at concentrations of 5%, 10%, and 15% by weight into epoxy resin, followed by the fabrication of composites using the hand lay‐up technique. Detailed structural analysis of HEA particles confirmed the successful synthesis of equatomic HEAs via MA. Structural analysis of the HEA integrated composites revealed vacancy regions at 5% concentration, a uniform distribution at 10%, and particle agglomeration causing inhomogeneity and vacancies at 15%. The composites demonstrated significant improvements in EMI SE, with the 10% HEA sample showing superior performance compared to the other samples. Specifically, the 10% HEA composite achieved a peak SE of 73.09 dB at 4.72 GHz, attributed to the optimized distribution of HEA particles that enhanced electrical conductivity and reflective properties. CoCuFeNi HEA particles were successfully synthesized via MA. HEA particles were added to epoxy at 5, 10, and 15 wt% for composite fabrication. Voids were observed in HEA5, uniformity in HEA10, and clustering in HEA15. EMI shielding was assessed using VNA, SE, dielectric permittivity, and magnetic permeability. The HEA10 composite achieved peak EMI shielding, 73.09 dB at 4.72 GHz. [ABSTRACT FROM AUTHOR]

Highlights To predict the coefficient of thermal expansion (CTE) of carbon fiber/epoxy resin composites with void defects comprehensively and accurately, a comprehensive study is carried out by integrating experiment, analytical model (ANM), and finite element model (FEM). The experiments on composites are conducted combining with Micro‐CT to provide geometric parameters and verification for ANM and FEM. An ANM considering void defects is established based on the Chamis model to investigate the influence of porosity, temperature and the ratio of modulus of the constituents of composites. A FEM is established to verify the ANM and reveal the mechanisms of the influence of void defects. The results show that the proposed ANM has high agreement with FEM and experiment. The longitudinal CTE decreases by 61.94% as the porosity increases from 0% to 20% at 60°C, and the same change of porosity results in a 15.62% decrease at 180°C. The transverse CTE is less susceptible to changes in porosity, showing reductions of 2.32% at 60°C and 3.33% at 180°C. An innovative model is proposed to predict CTE considering void defects. The glass transition temperature Tg of the resin has a significant effect on CTE. Void defects change the homogeneity of the original stress field of the matrix. The reduction of the longitudinal CTE caused by void defects is more significant. [ABSTRACT FROM AUTHOR]

Highlights Stemming from the cost‐effectiveness and broad applicability, many modification researches on Bisphenol A epoxy resin (DGEBA) and its carbon fiber composites have been done extensively. Here, following the concept of molecular composite, we prepared fully aminated p‐polyaramid with reactive amino side groups by polycondensation and reduction reaction, aiming to construct a molecular distribution of the reinforcement within the resin matrix and achieve a satisfactory enhancement effect. Among them, after adding 1 wt% fully aminated p‐polyaramid, Young's modulus and tensile toughness of the DGEBA epoxy resin (EP) increased significantly to 2.34 ± 0.03 GPa (+68.3%) and 4402 ± 213 kJ/m3 (+30.5%), the flexural modulus and toughness reached 4.14 ± 0.04 GPa (+42.8%) and 0.44 ± 0.01 J (+83.3%). Moreover, the Tg of EP was only decreased by 2.7°C. In addition, their warp‐knitted bidirectional carbon fiber composites also have enhancements in both flexural properties and interlaminar shear strength (all improved by more than 20%). What is noticeable is that the preparation and blending of fully aminated p‐polyaramid are simpler and more effective than most other micro‐ or nanofillers, and the dispersion is more uniform. Thus, it can act as a highly effective reinforcement and strengthen the properties of DGEBA and its carbon fiber composite materials significantly. Fully aminated p‐polyaramid is uniformly dispersed in EP by chemical bonds. DGEBA is strengthened and toughened without a significant decrease in Tg. The tensile and flexural modulus of EP is increased by 68.3% and 42.8%. Fully aminated p‐polyaramid can reinforce warp‐knitted carbon fiber composite. [ABSTRACT FROM AUTHOR]

To improve the dielectric properties and corona resistance of epoxy resins (EPs), the authors designed and synthesized Si‐B‐Mg/EP nanocomposites and investigated the effects of varying the magnesium elemental content on the dielectric properties, breakdown field strength, corona resistance life, volume resistivity and conductive current of Si‐B‐Mg/EP nanocomposites. The experimental results show that when the molar ratio of Si, B, and Mg in the Si‐B‐Mg composite oxide is 18:2:0.125, the composite has the minor dielectric loss and the most extensive corona resistance life of 401.8 min, which is 4.6 times that of the pure EPs. From the experimental results, the introduction of magnesium can effectively improve the dielectric loss and corona resistance of Si‐B‐Mg/EP composites. Highlights: Si‐B‐Mg composite oxides were designed and synthesized.Performance analysis of Si‐B‐Mg/EP composites with different magnesium contentThe introduction of magnesium reduces the dielectric loss of composites.The introduction of magnesium improves the corona resistance life of composites.Si‐B‐Mg/EP composites with both low dielectric loss and high corona resistance. [ABSTRACT FROM AUTHOR]

In order to enhance the mechanical performance of carbon fiber/epoxy resin composites (CF/EPs), a series of γ‐Al2O3 nanosheet/graphene (AG) composites were prepared by hydrothermal method, and successfully introduced into the carbon fiber (CF) surface via self‐assembly process, which significantly improved the interfacial bonding force between CF and EP. Mechanical test results showed that the AG modified CF/EPs exhibited superior properties in interfacial shear strength (IFSS), interlaminar shear strength (ILSS), tensile strengths, and flexural strengths compared with the untreated CF/EPs, which were enhanced by 142.9%, 59.6%, 152.5%, and 40.5%, respectively. This is mainly because AG largely increases the CF surface roughness and penetrates into the matrix to enhance the mechanical interlocking effect, crack deflection effect, and Van der Waals forces between CF and polymer matrix. Briefly, the AG synthesized in this study will provide an experimental validation for the development of high‐performance carbon fiber reinforced polymer composites (CFRPs) and exhibit potential application prospects in automotive and other fields. Highlights: Graphene effectively inhibits the agglomeration of γ‐Al2O3 nanosheet.γ‐Al2O3 nanosheet/graphene increases the interfacial properties of CF/EPs.γ‐Al2O3 nanosheet/graphene largely enhances the mechanical performance of CF/EPs.The as‐prepared AGCF/EPs have potential application in automotive and other fields. [ABSTRACT FROM AUTHOR]

Highlights Effective and accurate adjustment of negative permittivity behavior is worthy of further investigation. Herein, pyrolytic carbon‐glass fiber felt/epoxy resin (PyC‐GFF/ER) metacomposites with tunable negative permittivity were prepared using an impregnation‐calcination method. The permittivity, electrical conductivity, and electromagnetic shielding performance of the polymer metacomposites were investigated. Due to the inherent three‐dimensional structural network of GFF, the PyC adhering to the surface of glass fiber easily formed a conductive network in the composites. As the PyC content increased in the ER composites, the conductivity mechanism changed from hopping conduction to metal‐like conduction. The ER composites with high PyC contents showed negative permittivity behavior and the epsilon‐near‐zero response owing to the low frequency plasma state of free electrons in the PyC‐conduction network. By controlling the PyC content, the negative permittivity behavior of ER composites could be effectively tuned. With the increase in PyC content, the values of negative permittivity increased, and the epsilon‐near‐zero frequency shifted to a higher frequency. Moreover, the ER composites with high PyC contents showed excellent electromagnetic shielding properties (29.4 dB) at X‐band. This work not only provided a feasible method to realize the tunable negative permittivity of polymer metacomposites, but also promoted its application in the microwave field. The pyrolytic carbon‐glass fiber felt/epoxy resin composites were fabricated. The negative permittivity was first reported in the PyC‐GFF/ER composites. Tunable negative permittivity could be well explained by Drude model. The polymer composites had excellent electromagnetic shielding property. [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]

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]

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]

The use of natural fibers has been suggested by researchers for the purpose of promoting environmental sustainability. In this work, hybrid composites made of coir and banana fibers were fabricated by using both green resin and epoxy resin in the preparation of composites. Soybean oil is used in this work as the eco‐friendly resin. To determine the mechanical characteristics of the composites, a number of experiments were carried out including tensile, compression, hardness and impact tests. In addition, testing was done on the sound absorption qualities. Composites composed of green resins exhibit superior environmentally friendly characteristics and mechanical robustness in comparison to composites based on epoxy resin. The tensile strength of the hybrid composites exhibited superior performance compared to other hybrid composites. The additional mechanical qualities of the hybrid composites are noteworthy and serve as a driving force to pursue the development of specific applications. Highlights: Hybrid composites exhibit superior mechanical properties.The use of natural resin‐based composites is limited.There is a potential scope for developing hybrid composites using natural fibers and resin for acoustic applications. [ABSTRACT FROM AUTHOR]

In this study, we compare synergistic performance of two different nanofillers, namely halloysite nanotubes (HNT) clay and multiwalled carbon nanotubes (MWCNT), in conjunction with a fixed concentration (0.125 phr) of semi‐anthracite coal‐derived graphene oxide (AC‐GO) on mechanical properties improvement of EGFPs (E‐glass fiber‐based epoxy resin composites). The dispersion of AC‐GO with HNT clay (GO‐H) and AC‐GO with MWCNT (GO‐C) within epoxy matrix was achieved using sonication and homogenization. Further mixture was incorporated into mats of E‐glass fiber employing "vacuum‐assisted resin infusion molding" (VARIM). Significant enhancements (18.3% flexural strength, 14.6% tensile strength, and a slight increase of impact strength (1.8%)) were observed in EGFPs reinforced with GO‐H at 0.50 phr loading of HNT, with an AC‐GO concentration maintained at 0.125 phr. Correspondingly, optimal values for GO‐C reinforced EGFPs at 0.25 phr were 40.3%, 18.7%, and a 10.5% decrease in impact strength, respectively. Analytical techniques such as XRD, FESEM, EDX mapping, and FTIR reveal presence of relatively abundant functionalities and strong interfacial adhesion in GO‐H as well as GO‐C. The cost of HNT clay is approximately 15 times cheaper than industrial‐grade MWCNTs, therefore, these results underscore potential of GO‐H as a very economical nano‐reinforcement alternative to GO‐C for polymer nanocomposites. Highlights: 0.50 phr HAGRP improves 18.3% flexural, 14.6% tensile, 1.8% impact strengths.Beyond 0.50 phr HAGRP and 0.25 phr CAGRP, mechanical properties decreased.0.25 phr CAGRP improves 40.3% flexural, and18.7% tensile strengths.FESEM, FTIR reveal strong interfacial adhesion between nanofillers and epoxy.GO‐H has proven to be an inexpensive reinforcement for polymer nanocomposites. [ABSTRACT FROM AUTHOR]

When composite honeycomb sandwich structures are subjected to low energy impacts, the upper panel or the honeycomb core often suffers large damages, which are invisible, but affects the structural safety. To achieve non‐destructive detection of these damages, an epoxy resin film (ERF) was designed as a functional coating to display the internal failure features on structure surface. The effect of low energy impacts on the damage modes of the ERF was first investigated, and then the correspondence between the ERF damage characteristics and the structural internal failure was established. Simulation and experimental results showed that with the increase of impact energy, cracks on the ERF expanded from the radial radiation with a small extension range to the circumferential pattern with an increased damage area. Meanwhile, localized delamination appeared inside the upper panel, while the degree of flexure and crushing damage to the core continued to increase. Based on the analysis of the crack extension pattern of the ERF and the damage state of the upper panel and honeycomb core, a specific link between the ERF crack characteristics and the internal damages to the sandwich structure was obtained, which might offer a novel non‐destructive testing method for composite impact damages. Highlights: Low energy impact damage in honeycomb sandwich structures was a concern.Impact damage response of epoxy resin film on sandwich composites was studied.Crack extension of the film showed a particular change from radial to annular.Specific link between film crack and sandwich structure damage was established.The results would be helpful for damage detection in sandwich composites. [ABSTRACT FROM AUTHOR]

Highlights This paper investigates the high thermal conductive properties of modified hexagonal boron nitride (h‐BN)/epoxy (EP) composites. Octadecyl trimethyl ammonium bromide as a cationic surfactant modified h‐BN and sodium carboxymethylcellulose to build 3D heat transfer framework by the ice template method and preparation of epoxy composites. The h‐BN was modified by inter‐ionic charge electrostatic attraction to improve the h‐BN dispersibility; characterization by scanning electron microscope, transmission electron microscope, zeta potential, x‐ray diffraction and Fourier transform infrared spectroscopy proved the success of h‐BN surficial modifyment. 3 wt% sodium carboxymethylcellulose was used to construct the optimal 3D modified h‐BN network, and the w‐BN/EP composites had a very high heat conduction; when the composite material acquired by the ice template method have high heat transfer coefficient, 1.57 W/(m K) for 25 wt% 3D modified h‐BN/EP heat transfer coefficient and 0.76 W/(m K) for modified h‐BN/EP at the same ratio, which is a 107% enhancement in heat transfer efficiency, and 0.12 W/(m K) for EP, which is a 1208% enhancement in thermal conductivity. The results of thermogravimetric analysis (thermogravimetric analysis and differential thermogravimetric analysis), differential scanning calorimetry, and infrared thermography indicate that the thermostability and rejection of heat of composite material was significantly improved. The variation of dielectric constant was stabilized to ensure lower dielectric loss. Overall, this study can better adapt to high‐frequency signal transmission. Use octadecyl trimethyl ammonium bromide to modify the interface of hexagonal boron nitride (h‐BN) enhances the dispersibility and reduces the inter‐facial heat resistance with epoxy resin through inter‐ionic electrostatic attraction. The optimal content of sodium carboxymethyl cellulose was selected to construct a 3D mesh framework with the modified h‐BN to ensure the formation of a continuous and homogeneous network at the maximum porosity. The 3D modified h‐BN network was prepared by the ice template method to reinforce the heat conductivity of the composite materials. [ABSTRACT FROM AUTHOR]

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

Highlights The bonding interface of carbon‐fiber‐reinforced polymer (CFRP)‐reinforced steel structure is a weak part, and nanomaterial‐modified adhesives are expected to improve its comprehensive performance. This paper investigates the micro‐modification mechanisms of nanomaterials on epoxy resin adhesives using molecular dynamics simulation method. It explores how the functionalized nano SiO2 and carbon nanotubes affects the thermal and mechanical properties of the epoxy resin adhesive. The models established using Materials Studio software include the pure epoxy resin adhesive model (EP) with varying degrees of crosslinking, the functionalized nano‐SiO2‐modified epoxy resin adhesive model (EP + SiO2/OH), the single‐walled carbon nanotube‐modified epoxy resin adhesive model (EP + SWNT), and the synergistic enhancements model of the epoxy resin adhesive with nano‐SiO2 and carbon nanotubes (EP + SWNT + SiO2/OH). Based on the aforementioned models, the Forcite module is used to calculate the free volume, glass transition temperature and mechanical properties of the adhesive. The results show that the degree of crosslinking effects significantly the mechanical performance of epoxy resin adhesive. A high degree of crosslinking restricts the movement of the molecular chain, enhancing the strength of the epoxy resin adhesive. Furthermore, the trend of the mechanical and thermal properties of the four models remains constant with the rise of temperature, and the properties decrease most significantly in the range of the glass transition temperature. Moreover, the epoxy resin adhesive doped with nanomaterials exhibits varying degrees of enhancement in mechanical and thermal properties. The epoxy resin adhesive reinforced with functionalized nano‐SiO2 and carbon nanotubes exhibits better properties compared to those with a single nanomaterial. The micro‐modification mechanism is revealed for nanomaterial modified epoxy resin adhesive. The degree of crosslinking effects significantly the mechanical performance of epoxy resin adhesive. The epoxy resin adhesive doped with nanomaterials exhibits varying degrees of enhancement in mechanical and thermal properties. [ABSTRACT FROM AUTHOR]

Highlights Bulk molding compound (BMC) manufactured using fiber reinforced polymers (FRPs) has attracted extensive attention and is widely used because of its capability to fabricate structures with complex shapes. This study investigated the effects of aging on the mechanical properties of BMC composites made using an epoxy matrix and discontinuous carbon fibers of varying lengths. Tensile, compressive, and flexural tests were conducted. The results showed that longer fibers did not necessarily increase the moduli and strengths of BMC composites due to stress concentrations resulting from the curling and entanglement of the longer fibers. When aged, BMC composites using shorter carbon fibers exhibited more significant reductions in moduli and strengths due to higher void contents, resulting in more severe matrix epoxy degradation. When comparing epoxy and BMC, BMC experienced greater reductions in moduli and strengths even though carbon fiber, a type of artificial fiber, should be less affected by aging. This is because aging not only degraded the matrix epoxy but also affected the adhesion between the fibers and the matrix, leading to a larger displacement of the fibers, resulting in a more severe reduction in the mechanical properties of the BMC composites. BMC composites were manufactured using epoxy and discontinuous carbon fibers. Longer fibers did not necessarily increase strengths due to entanglement. BMC using shorter fibers had more voids and hence degraded more severely. BMC showed greater strength reductions than epoxy due to matrix degradation. Degradation of matrix epoxy affected the adhesion between fibers and matrix. [ABSTRACT FROM AUTHOR]

Crash boxes are safety elements generally made of metallic materials and mounted on the chassis of vehicles to prevent possible injuries to driver and passengers by absorbing the energy generated during a collision and ensuring integrity of vehicle. In order to save fuel and reduce harmful gases released into the environment, the proportion of metallic materials used in vehicles is decreasing and being replaced by composite materials. While composite materials are as durable as metallic materials, they are preferred because they are lighter. In this study, circular composites consisting of glass (S1), aramid (S2), carbon (S3), and hybrid combinations of aramid‐carbon‐glass (S4), carbon‐glass‐aramid (S5), and glass‐aramid‐carbon (S6), all with epoxy resin matrices, were produced using the vacuum infusion method and investigated. Crush parameters, maximum peak loads and specific energy absorption of hybrid tubes with different fiber types and winding order were compared. S3 tube had the best energy absorption performance among all samples of 257.288 Joules, while the worst energy absorption performance was obtained for S2 tube with 30.944 Joules. Among the hybrid samples, the best result was determined as 166.50 Joule with hybrid S5. Although the energy absorption capacities of hybrid composite tubes were close to each other, they had lower results for energy absorption and specific energy absorption than S1 and S3. For specific energy absorption, as with energy absorption, the best result was obtained with S3, while the lowest result was obtained with S2. Highlights: The aim of this study is to evaluate the performance of composite crash boxes.The effect of fiber type and hybridization was examined.Specific energy absorptions and maximum contact forces were compared.Cylindrical samples were produced by vacuum infusion.The variation of damage depending on fiber type was investigated. [ABSTRACT FROM AUTHOR]

Fiber reinforced polymer (FRP) bars have received extensive promotion and application in the structural engineering. However, due to the limitations inherent in using single material, FRP reinforced concrete structures often encounter issues, such as brittle failure and inadequate energy dissipation, particularly in complex natural environments and under various loading conditions. In this study, the preparation of nano‐SiO2‐modified carbon/basalt hybrid FRP bars was carried out using the pultrusion‐winding process and ultrasonic treatment. The objective was to investigate the influence of the fiber volume ratio and mass fraction of nano‐SiO2 on the mechanical properties of FRP bars under drying and alkaline conditions. Molecular dynamics simulations were performed to construct interface models between fibers and epoxy resin in order to elucidate the toughening mechanism of nano‐SiO2 and the degradation mechanism in alkaline conditions. The research results show that elevating the substitution rate of carbon fibers and incorporating nano‐SiO2 doping bring about alterations in the brittle fracture characteristics of BFRP bars and enhance the post‐yield performance and interlaminar shear properties of hybrid FRP bars, concurrently mitigating the degradation of mechanical properties induced by exposure to alkaline solutions. MD simulations indicate that the addition of nano‐SiO2 improves the binding rate of hydrogen bonds between BF and epoxy resin, resulting in a higher interfacial energy between BF/epoxy resin compared to CF/epoxy resin. Moreover, nano‐SiO2 effectively mitigates the impact of alkaline solutions on the formation of interfacial hydrogen bonds. The findings of this study serve as a valuable reference for the design and application of FRP reinforced concrete structures. Highlights: Nano‐SiO2 modified B/CFRP bars made via extrusion‐winding & ultrasonic treatment.Improved mechanical properties and plastic deformation in Nano‐SiO2 modified B/C FRP bars.Nano‐SiO2 inhibits B/CFRP bars degradation in alkaline solution.Nano‐SiO2 bind more at BF/epoxy than CF/epoxy interface.Nano‐SiO2 reduces alkaline solution effect on interfacial H‐bonding. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced epoxy resin matrix composite is one of the most important composite materials in the world. Many researchers have conducted a lot of research on epoxy resin matrix systems in recent years, mainly to improve the problem with the short curing time of the matrix system and epoxy resin's high viscosity. The final aim is to enhance various aspects of composites' performance and optimize the production process. A new type of water dispersed epoxy resin matrix system is investigated in this paper and the target is to optimize the mechanical, thermal, and electrical performances of the composites with the water dispersed epoxy resin matrix by varying different doping particles and different resin/catalyst ratios. Through a series of experiments, it is evident that varying the ratio of resin to catalyst in the matrix system will not significantly improve the mechanical as well as thermal properties of the composites. However, increasing the amount of catalyst in the matrix system can greatly improve the electrical properties of its composite samples. In addition to this, the addition of doping particles to the matrix systems has the effect of slightly enhancing the tensile modulus, thermal conductivity, and electrical conductivity of their composites. Highlights: A new water‐dispersed epoxy resin matrix system improves processing technology.Increasing amount of catalyst in the matrix system improves electrical resistivity.Adding particles to matrix systems has a slight effect on different properties. [ABSTRACT FROM AUTHOR]

This study aimed to explore the application of a mechanochemical method for effectively integrating polyimide nanofibers, which are widely recognized for their outstanding thermal and mechanical properties, into an epoxy resin matrix. The researchers observed an 87.5% reduction in the diameter of polyimide nanofibers after mechanical treatment. The dispersion, compatibility, and interface between the nanofibers and epoxy matrix were analyzed using molecular dynamics simulations and scanning electron microscopy. The addition of polyimide nanofibers significantly increased the binding energy of the composite, resulting in a 52.8% improvement. Moreover, compared to pure epoxy resin, the inclusion of modified polyimide nanofibers led to a 21.9% increase in tensile strength and an 18.8% increase in impact strength. The PI/epoxy composite also exhibited a 15.6% increase in tensile strength and a 16.4% increase in impact strength. Additionally, electrochemical corrosion analysis showed that the PI/epoxy composite had excellent corrosion resistance. In conclusion, due to the exceptional mechanical properties and strong interfacial adhesion of polyimide nanofibers, the PI/epoxy resin composite demonstrated significant overall performance improvement compared to pure epoxy resin. Highlights: Mechanochemical method to disperse polyimide fiber, shorter and finer fibers were obtainedImprove performance by adding small amountsMicroscopic analysis of composites by Materials Studio, PIENFs efficiently improved the interaction on the phase interfaceExperiments have verified that PIENFs could make the mechanical properties and corrosion resistance [ABSTRACT FROM AUTHOR]

Chemical grafting is commonly employed to functionalize carbon fiber (CF) surface to enhance the interfacial properties of CF reinforced polymer composites (CFRP) by forming a robust interface. However, an overly rigid interface layer can result in relatively poor interface toughness. To balance interfacial strength and toughness, this paper proposes an effective method to simultaneously strengthen and toughen the interface of CF/epoxy composites by grafting branched polyethyleneimine (PEI) on CF surface using hexachlorophosphazene (HCCP) as active intermediate, which features a rigid ring structure and six active P‐Cl groups. The introduction of PEI provided a large number of amine and imine groups on CF surfaces, which were contributive to improving surface wettability and reactivity of CF, thus resulting in strong chemical bonding between CF and epoxy matrix. Additionally, the long and flexible molecular skeleton of PEI constructed a rigid‐flexible composite interface, which could effectively reduce stress concentration and absorb impact energy. After surface modification with PEI, the interfacial shear strength and fracture toughness of CF/epoxy composite were increased to 89.9 MPa and 200.3 J m−2, by 64.3% and 149.7%, respectively, in compared with desized CF reinforced epoxy composites. Highlights: A rigid‐flexible interface was constructed between CF and epoxy resin.The interfacial strength and toughness of CFRP were synergistically improved.IFSS and interfacial toughness increased by 64.3% and 149.7%, respectively. [ABSTRACT FROM AUTHOR]

The matrix cracking of carbon fiber reinforced epoxy resin based composites (CFRPs) at cryogenics (such as liquid nitrogen temperature) is a major issue affecting the normal operation of deep space and deep‐sea detectors, as microcracks caused by the thermal residual stress of both can reduce the structural integrity of the devices. In this work, we report an epoxy (EP) nanofiller CuO nanorods (CuO NRs) with negative thermal expansion properties at cryogenics. Experiments showed that CuO NRs can effectively inhibit the shrinkage of EP at cryogenics and improve the mechanical properties of EP at cryogenics. A temperature dependent prediction model for the tensile strength of EP/CuO NRs was proposed, and the predicted results were in good agreement with experimental results. Finally, through a combination of experiments and theory, it was demonstrated that the tensile strength of EP/CuO NRs at cryogenics is jointly enhanced by the enhancement effect of the nanomaterials and the axial compressive thermal residual stress between EP and CuO NRs. Highlights: Successfully prepared CuO nanorods with negative expansion properties at low temperatures, and found that they can effectively inhibit the shrinkage of epoxy resin at cryogenics.At cryogenics, the expansion of CuO nanorods enhances their interface effect with epoxy resin and improves the tensile strength of epoxy resin composites.The theory of tensile strength of epoxy resin at cryogenics was proposed for the first time. Theoretical analysis shows that the low temperature residual thermal stress between CuO nanorods and epoxy resin is the main factor to improve its tensile strength. [ABSTRACT FROM AUTHOR]

Highlights To improve the subpar lubricating performance of epoxy resin, this paper presents the preparation of a novel bimetallic phyllosilicate featuring a distinctive rice‐granular morphology, which incorporates nickel and iron metal cations through a facile hydrothermal process. These phyllosilicates were then integrated into the epoxy matrix to form composites. A comprehensive analysis of the target product validates the rationality of the synthesis strategy for the as‐prepared rice‐granular bimetallic nickel/iron phyllosilicate, demonstrating a homogeneous hierarchical structure with numerous tiny nanosheets of nickel/iron phyllosilicate grown in situ on the flat surfaces of the rice‐granular metal–organic frameworks. An adequate addition of nickel/iron phyllosilicates allows for excellent dispersion within the matrix and establishes strongly bonded interfaces, steadily increasing the elastic modulus and hardness. Notably, the average friction coefficients decrease from 0.515 for the pure resin to 0.450 for the composites when the filler content reaches 7%, indicating a significant solid lubrication effect. In contrast, adding just 1% nickel/iron phyllosilicate moderately improves wear resistance, elongation at break, and tensile strength. Furthermore, it was found that as the filler content increased, the weight loss rate was reduced by approximately 43.8%, while the residual char increased by 74.2%, significantly enhancing the thermal stability of epoxy composites at high temperatures. This study offers a promising approach to preparing self‐lubricated epoxy composites with favorable mechanical and thermal properties. NiFePS was successfully synthesized via a facile two‐step self‐polymerization. Excellent mechanical properties of composites could be achieved with low content of NiFePS. The friction coefficient and wear rate were lowered remarkably. The friction mechanism was solid lubrication. [ABSTRACT FROM AUTHOR]

Highlights The present work highlights the benefits of matrix strengthening through the inclusion of hard particles within the resin‐impregnated woven Kevlar mat. Aluminium Oxynitride (ALON) particles are added to epoxy resin by 5, 10, and 15 volume percentages. The test coupons were developed through a hand‐lay‐up technique to estimate the low‐velocity impact resistance. The characterization was performed through EDAX and SEM to ensure the presence of the ALON particles and their homogenous distribution respectively. Low‐velocity testing is preferred to assess the capacity of the materials to rebound the incident energy. The damage assessment was made to estimate the material's stiffness. The compression after impact (CAI) was executed to observe the strength of the material after the impact. The post‐CAI micrographic observation reveals the delamination history. The results manifest that the ALON–rich coupon exhibits higher impact resistance to the scale of 33.33% than that of the ALON‐free coupon. The damage assessment and CAI results annunciate the lesser damage and higher compressive strength of ALON‐rich material respectively. The micrographic study studied after the CAI reveals the delamination and failure behavior. Additionally, explicit numerical assessment was conducted to validate the experimental results. A good agreement is attained between the experimental results and numerical predictions. The enriched stiffness of the synthesized material makes it a perfect candidate for structural application where the frequency of impact loading is high. Development of ALON reinforced Kevlar‐Epoxy composites for low‐velocity impact applications. Evaluating the performance of developed composites under low‐velocity impact loading. Determining the optimal volume percentage of ALON in the composites. Studying the fractography of developed composites. Correlation between experimental and numerical studies. [ABSTRACT FROM AUTHOR]

In this paper, a dense and well‐adherent polydopamine‐Ti4O7/epoxy resin (PDA‐Ti4O7/EP) composite coating is successfully prepared. The modified grafting of Ti4O7 by polydopamine (PDA) is achieved through the coordination complexation of unstable catechol groups in PDA with coordination unsaturated Ti atoms in Ti4O7. The potentiodynamic polarization curve and electrochemical impedance spectroscopy test results show that the performance of the composite coating is improved compared with that of the pure epoxy coating, and the composite coating slows down the penetration of electrolytes and aggressive ions and improves the corrosion resistance. The composite coating with 2 wt.% PDA‐Ti4O7 filler shows the best corrosion resistance, and its |Z|0.01 Hz remains above 1011 Ω cm2 after 30 days of immersion in 3.5 wt% NaCl solution. This can be attributed to the good barrier property of PDA‐Ti4O7 filler, which carries NH2 and OH reactive groups, interacting with the resin and matrix to improve the dispersion of the filler and the adhesion of the composite coating. The NH2 group reacts with the epoxy group in the epoxy resin in a ring‐opening reaction, which avoids the agglomeration of the filler and the uniformly dispersed filler fills the pores in the coating due to curing to improve the denseness of the coating and give full play to the barrier property of the filler. At the same time, the hydrogen bonding between the filler and the OH group in the resin and the substrate increases the adhesion of the coating. In addition, the unstable catechol group in PDA chelates with iron ions to further improve the overall corrosion resistance of the coating. Highlights: A dense and well‐adherent PDA‐Ti4O7/EP coating is successfully prepared.PDA connect with Ti4O7 through coordination of catechol groups and Ti atom.PDA‐Ti4O7 are chemically bonded to the EP through a ring‐opening reaction.PDA‐Ti4O7 improves the crosslinking density and barrier ability of the coating. [ABSTRACT FROM AUTHOR]

The relationship between interfacial structure and thermal conductivity in epoxy resin/Al2O3 composite is important but is still elusive. Here, we illuminate this issue by investigating the role of four silane coupling agents in thermal conductivity for epoxy resin/Al2O3 composites. The results show that 3‐glycidoxypropyltrimethoxysilane (KH560) is the best silane coupling agent to modify Al2O3, resulting in the lowest viscosity and the highest thermal conductivity of the epoxy resin/Al2O3‐KH560 composite compared with alternative systems. This is attributed to the strong interfacial interaction between Al2O3‐KH560 and epoxy resin, as confirmed by the Fowkes model and broadband dielectric spectroscopy. The interfacial thermal resistance between the epoxy resin and Al2O3 is also quantitatively measured via a photothermal radiometry technique. The epoxy resin/Al2O3‐KH560 also has the lowest interfacial thermal resistance (1.50 ± 0.02 × 10−6 m2 K W−1), compared with the other three systems. This study advances the understanding of the relationship between interfacial structure and thermal conductivity in polymer composites. Highlights: The relationship between interfacial structure and thermal conductivity in epoxy resin/Al2O3 composite is understood.The interfacial structure is characterized by broadband dielectric spectroscopy.The interfacial thermal resistance is quantitatively measured via a photothermal radiometry technique. [ABSTRACT FROM AUTHOR]

Polymer composites with thermal conductivity are attractive for heat dissipation in electronic devices. We prepared epoxy resin‐based composite films filled with polythiophene [poly(3‐hexylthiophene‐2,5‐diyl)] (P3HT)/graphene complex or aluminum nitride (AlN). The composite films were characterized by electron microscopic observation, thermogravimetric analysis, and thermal conductivity measurements. The addition of a small content of P3HT/graphene complex (<1 wt%) increased both the out‐of‐plane and in‐plane thermal conductivities of the epoxy resin. The addition of AlN also increased thermal conductivity, but ≥40 wt% was required to obtain thermal conductivity comparable with that of an epoxy resin film doped with 0.9 wt% P3HT/graphene complex. The present results illustrate the potential of P3HT/graphene complexes as fillers for improving the thermal conductivity of epoxy resins without affecting their insulating properties. Highlights: Polythiophene/graphene fillers increased epoxy resin films' thermal conductivity.To raise the thermal conductivity of epoxy resin films high AlN content was needed.In‐plane/out‐of‐plane epoxy resin films' thermal conductivities were evaluated. [ABSTRACT FROM AUTHOR]

In this article, the axial crushing behavior of CoFeSiB amorphous alloy fiber reinforced epoxy composites (AAFRCs) with different fiber volume fractions (30%, 40%, 50%, and 60%), fiber orientations (0°, 15°, and 30°), and fiber shapes (straight and sinusoidal) were investigated under compression condition. The results show that energy absorption (EA) and crush force efficiency (CFE) of the composites show a tendency to increase and then decrease with the increase of fiber volume fractions. The appropriate increase in fiber orientation can improve the EA and the CFE of the composites. The EA of reinforced composites with sinusoidal fiber is 66% higher than that of the ones with straight fiber. Three damage modes were identified by combining the damage process images corresponding to the compressive load–displacement curves and the morphologies of the crushed composites. The EA mechanism of the new composites was analyzed by observing the damage process of the AAFRCs. Highlights: A novel CoFeSiB amorphous alloy fiber reinforced epoxy composites.The increase in fiber orientation improves the energy absorption and the crush force efficiency of the composites.The energy absorption of reinforced composites with sinusoidal fiber is higher than that of the composites with straight fiber.Three damage modes were identified: compression damage, axial bending and transverse shear. [ABSTRACT FROM AUTHOR]

Fiber reinforced polymer composite structures are particularly vulnerable to high temperatures as their strength drastically reduces under elevated temperature conditions. Therefore, it is important to improve the thermal stability of such composite structures to expand their potential range of applications. In this study, the effect of mixing two epoxy monomers, DGEBA and Tactix 742, which are di‐ and tri‐functional, respectively, on the thermal stability of their composites is investigated. The thermo‐mechanical analysis of these composites revealed that the glass transition temperature rose from 123 to 229°C when Tactix 742 is increased from 25% to 75%. The thermal resistance property is attributed to a three‐dimensional crosslink network which is initiated by tri‐functional Tactix 742. However, the higher percentage of Tactix led to a reduction in strength, possibly due to decreased crystallinity and formed amorphous phase material. Subsequently, a tensile strength model was employed to assess the performance at elevated temperatures. It was shown that a matrix with a mix of di‐ and tri‐functional monomers is highly promising for manufacturing thermoresistant polymeric composites with robust mechanical properties, thereby expanding their potential applications across various engineering fields such as civil and construction industries. Highlights: A thermoresistant matrix by blending di‐ and tri‐functional epoxy monomers.Improved thermo‐mechanical properties and increased glass transition temperature of fiber reinforced composites.Mechanical performance of carbon fiber reinforced composites at elevated temperatures.Validated a model to estimate the tensile strengths of the composites at elevated temperatures. [ABSTRACT FROM AUTHOR]

A sizing agent mainly consisting of polyethersulfone and acidified multi‐walled carbon nanotubes (MWCNT) was developed for surface modification of carbon fibers (CF) to enhance the interfacial bond and to form carbon fiber‐carbon nanotube (CF‐MWCNT) multiscale reinforcements. To prepare the modified carbon fiber/epoxy resin composites (CFRP), a vacuum molding technique was used in this study. The effects of the MWCNT‐containing sizing agent on the morphology and chemical structure of the CF surface were observed by scanning electron microscopy and Fourier transform infrared spectroscopy. The influence of MWCNT length and content on the mechanical properties of CFRP were also studied. The experimental results showed that the strength of the CFRP decreased with the increase of MWCNT length, and the MWCNT with a content of 0.05 wt% had a good reinforced effect on the CFRP. After the sizing treatment, the interlaminar shear strength (ILSS) of the CFRP is increased. These enhancements are attributed to the improved mechanical bonding and chemical bonding between CF and resin matrix. The MWCNT provides nanosized rough surface to CF and these acidified MWCNTs attached to the surface of CF with polar oxygen‐containing functional groups improve the compatibility with reinforcement and resin matrix. Highlights: Carbon fiber was modified by a sizing agent mainly consisting of polyethersulfone and acidified carbon nanotube (CNT).CNTs enhance the interfacial chemical bonding and mechanical bonding.The CNT length affects the mechanical properties of the carbon fiber/epoxy resin composites (CFRP).The modified carbon fiber has enhanced the mechanical properties of the CFRP. [ABSTRACT FROM AUTHOR]

Highlights Highly thermal conductive polymer coating is delivered from blending thermal conductive fillers, yet sacrificing the mechanical properties, e.g. anti‐erosion, and mechanical flexibility. In this work, highly thermal conductive, mechanical flexible and anti‐erosion epoxy resin (EP)/graphite@La2O3 composite coating was developed via chemically modification. Polydopamine (PDA), γ‐methacryloxypropyltrimethoxysilane and n‐octyltrichlorosilane were used to graft La2O3 particles onto graphite (graphite@La2O3) to enhance interfacial compatibility. Graphite@La2O3 homogeneously dispersed in epoxy forming more thermal conductive pathways and layered structure. In‐plane and cross‐plane thermal conductivity of EP/graphite@La2O3 coating was 2.06 and 1.7 W/(m K), respectively. The temperature of EP/graphite@La2O3 composite coating increased from room temperature to 107.2°C in 60 s while the temperature of EP/graphite coating increased to 59.9°C within 60 s. Furthermore, dispersing graphite@La2O3 into epoxy significantly decreased the weight loss percentage from 0.17 to 0.05 mg/g while the hardness increased from around 7.0–16.77 HV, respectively. The fracture stress and strain of EP/graphite@La2O3 coating was 25 MPa and 6.0%, respectively, which is two times of EP/graphite coating. This is attributed to the chemically grafting La2O3 particles enhanced the interfacial compatibility, homogeneous dispersion and the formation of layered structures in epoxy. This study provides an effective approach to prepare thermal conductive epoxy coatings with multifunctional mechanical properties. La2O3 nanoparticles grafted on graphite successfully. Mechanical flexibility and anti‐erosion were improved by chemical grafting. Chemical modification improves the interfacial compatibility. The utilization of La2O3 nanoparticles induced the formation of layer structure. Layered structure offsets the stress improving thermal and mechanical property. [ABSTRACT FROM AUTHOR]

The development of electronic fuze has placed higher demands on encapsulation resins, which are required to provide not only insulation and protection, but also higher impact resistance and good electromagnetic shielding performance. A new composite material consisting of hollow glass microspheres (HGM) and modified epoxy resin was developed. This material exhibits significant electromagnetic shielding capabilities for terahertz (THz) waves, as well as superior impact energy absorption properties. Bisphenol A‐type epoxy resin (E‐44) was modified using Al(OH)3, red phosphorus, carbon black, and SiO2, and the material properties were optimized by adjusting the HGM content. The electromagnetic shielding effectiveness and impact energy absorption of the composite material in the THz band were comprehensively tested using THz time‐domain spectroscopy and split Hopkinson pressure bar testing systems. Additionally, a comprehensive evaluation of the mechanical and dielectric properties, thermal conductivity, and thermal stability of the material was conducted. The results showed that the electromagnetic shielding effect of 60 vol.% HGM hybrid‐modified resins was the best, reaching 43.78 dB. The 20 vol.% HGM hybrid‐modified resins not only has a specific absorption energy of 18.51 J/cm3, but also has the best overall performance. This work has advanced the design and development of multifunctional and impact‐resistant potting epoxy resins. [ABSTRACT FROM AUTHOR]