Tensile Fracture Toughness Research Articles

Cryogenic Impact on Carbon Fiber-Reinforced Epoxy Composites for Hydrogen Storage Vessels

Carbon fiber-reinforced epoxy (CF/EP) composites are attractive materials for hydrogen storage tanks due to their high strength-to-weight ratio and outstanding chemical resistance. However, cryogenic temperatures (CTs) have a substantial impact on the tensile strength and interfacial bonding of CF/EP materials, producing problems for their long-term performance and safety in hydrogen storage tank applications. This review paper investigates how low temperatures affect the tensile strength, modulus, and fracture toughness of CF/EP materials, as well as the essential interfacial interactions between carbon fibers (CFs) and the epoxy matrix (EP) in cryogenic environments. Material toughening techniques have evolved significantly, including the incorporation of nano-fillers, hybrid fibers, and enhanced resin formulations, to improve the durability and performance of CF/EP materials in cryogenic conditions. This review also assesses the hydrogen barrier properties of various composites, emphasizing the importance of reducing hydrogen permeability in order to retain material integrity. This review concludes by highlighting the importance of optimizing CF/EP composite design and fabrication for long-term performance and safety in hydrogen storage systems. It examines the prospects for using CF/EP composites in hydrogen storage tanks, as well as future research directions.

Mitigating aging infrastructure risks: An optimized epoxy resin system for water supply pipeline rehabilitation

Urban water supply networks are crucial for ensuring the delivery of safe drinking water to urban populations; however, the aging infrastructure in these systems has led to a rising incidence of leaks and frequent pipeline failures, posing serious risks. Traditional repair approaches encounter limitations in terms of efficiency, durability, and environmental safety, particularly when employed in potable water pipelines. To address these challenges, we developed a novel multi-component amine-cured epoxy resin system specifically optimized for in-situ curing under ambient conditions. This study comprehensively examines the mechanical properties, water absorption behavior, and curing kinetics of this resin system, formulated to reduce volatile organic compound emissions while enhancing durability under prolonged water exposure. Experimental findings demonstrate that the E2 formulation exhibited superior tensile strength, flexural properties, and fracture toughness relative to other formulations, with a two-stage water absorption model accurately predicting resin behavior in moisture-laden environments. Moreover, finite element modeling and laboratory testing confirmed the influence of bubble defects on mechanical performance, and a negative pressure defoaming technique effectively reduced defect volume, resulting in a 17.6% improvement in tensile strength. Collectively, this research advances the practical application of rapid-curing resins, offering a resilient, safe, and sustainable solution for the rehabilitation of aging water pipeline networks.

Mechanical properties of pure elements from a comprehensive first-principles study to data-driven insights

Unraveling mechanical properties from fundamental is far from complete despite their vital role in determining applicability and longevity for a given material. Here, we perform a comprehensive study related to mechanical properties of 60 pure elements in bcc, fcc, hcp, and/or diamond structures by means of pure alias shear and pure tensile deformations via density functional theory (DFT) based calculations alongside a broad review of existing literature. The present data compilation enables a detailed correlation analysis of mechanical properties, focusing on DFT-based ideal shear and tensile strengths ( and ), stable and unstable stacking fault energies ( and ), surface energy (), and vacancy activation energy (); and experimental hardness (), ultimate tensile strength (), fracture toughness (), and elongation (). The present work examines models, identifies outliers, and provides insights into mechanical properties, for example, (i) is correlated by , by or , and by ; (ii) data outliers are identified for Cr (related to , , , and ), Be (, , , and ), Hf ( and ), Yb (all properties), and Pt ( vs. ); and (iii) , , , , , , and are highly correlated to elemental attributes, while , , and especially are less correlated due mainly to experimental uncertainty. In particular, the present data compilation provides a solid foundation to model properties such as and of multicomponent alloys and of unstable structures like bcc Ti, Zr, and Hf.

Fracture properties of carbon/glass fiber composite laminates with surface scratch damage

Carbon/glass fiber reinforced polymer composite panels may experience minor surface scratches during processing or use. These shallow scratches can expand and potentially lead to dangerous fracture failure as the specimens are continually loaded. This study presents a closed form non-LEFM model for predicting the fracture performance of materials with slight scratches. First, 3-p-b tests and direct tensile tests were conducted on 115 carbon/glass fiber composite laminated panel specimens. A comparison of the two test methods revealed that 3-p-b tests were more suitable for analyzing quasi-brittle fracture in carbon/glass fiber composites. The tensile strength ft and fracture toughness KIC of 3-p-b specimens with and without notched were discussed using the weighted average calculation method to determine the thickness of the “composite” single-layer prepreg as the characteristic composite unit Cch. A normal distribution method was also introduced to analyze the experimental discrete points, covering almost all the experimental scatterers with desired reliability. Furthermore, the same method was applied to specimens with different layup methods, and the data analysis confirmed its effectiveness. As the seam-thickness ratio α increases within a certain range, the tensile strength ft showed an overall increasing trend and the peak load Pmax showed a decreasing trend. Additionally, the laboratory routine dimensions can be utilized to efficiently predict the fracture of large size members with defects at the same thickness, which is significant for the safe design of composite structures.

Making large-size fail-safe steel by deformation-assisted tempering process

Synergistically improving the strength and toughness of metallic materials is a central focus in the field of physical metallurgy. Yet, there is a noticeable lack of research in strengthening and toughening large-size metal components, whereas those components are extensively used in the modern industry. In this work, a deformation-assisted tempering (DAT) process was proposed to create a novel microstructure in 1.4 tons low-alloyed plain steel. After DAT treatment, the steel contains low dislocation density but high density of low-angle subgrain boundaries and dispersed spherical nano carbides. Such microstructure enables a much better combination of tensile strength and fracture toughness compared to the small-size quench and temper steels. The significant improvement in low-temperature impact toughness is due to the occurrence of delamination and subsequent large plastic deformation at the notch tip. The DAT process can provides a new strategy for the development of large-size fail-safe steel with excellent strength and fracture resistance.

Microstructure evolution and mechanical properties of bioinspired interpenetrating Ti2AlNb/TiAl matrix composite with a crossed-lamellar structure

TiAl alloys with low density, high creep resistance and high temperature performance are considered as candidate materials to replace nickel-based superalloys in the range of 700∼800 °C. However, the intrinsic brittleness of TiAl alloys has always been the biggest bottleneck restricting their development. In this paper, a bioinspired interpenetrating Ti2AlNb/TiAl composite with crossed-lamellar structure was prepared by combining selective laser melting (SLM) and vacuum hot press sintering (HPS) under the condition of 1150 °C/1 h/45 MPa, to improve the strength and toughness of the composite. Meanwhile, the metallurgical defects and microstructure of Ti2AlNb reinforcement skeleton printed under different volume energy densities (VEDs) were investigated, as well as the evolution of the microstructure at the interface region of the composite was systematically studied. What's more, we studied the mechanical properties of the composite including nanoindentation test, room temperature tensile and bending tests. The results show that the VED is 88.89 J/mm3, an almost completely dense reinforcement skeleton (∼99.8 %) is obtained. The interface region can be divided into four different reaction layers, namely LⅠ, LⅡ, LⅢ and LⅣ, due to the diffusion of elements. LⅠ is mainly composed of Othick/thin lath-like phase and O short rod-like phase. LⅡ is mainly composed of B2/β phase, acicular α2 phase and nanoscale ω-Ti3NbAl2 phase. The LⅢ mainly consists of B2/β phase. The LⅣ is composed of α2 phase. The deformability of each phase in the composite: B2/β phase > O phase >γ phase >α2 phase >ω phase. The tensile strength and fracture toughness of bioinspired interpenetrating Ti2AlNb/TiAl matrix composite are increased by 24.0 % and 89.0 %, respectively, compared with TiAl alloy, which is mainly contributed to the strong interfacial bonding between matrix and reinforcement as well as the synergistic effect of Ti2AlNb reinforcement with high strength and toughness.

Sustainably sourced and DOPO-derived triols as hardeners for epoxy thermosets: A promising solution to synchronously improve flame retardancy, mechanical strength and toughness

The flammability and brittleness of the diglycidyl ether of bisphenol A (DGEBA)-type epoxy resin greatly restrict its application in electronic appliances and structural materials. However, the synchronous improvement in the flame retardancy, mechanical strength, and toughness of DGEBA-type epoxy thermosets remains a significant challenge. To overcome this challenge, in this study, a sustainably sourced and DOPO-derived triol (DOPO-GL-DCDA) was synthesized from a bio-based material, glycerol 1, 3-diglycerolate diacrylate (GL-DCDA). A series of epoxy thermosets with different phosphorus contents were prepared by introducing DOPO-GL-DCDA into the DGEBA matrix. EP/DOPO-GL-DCDA demonstrated excellent flame retardancy and mechanical properties without compromising transparency. Specifically, EP/DOPO-GL-DCDA-1.0P exhibited a limit oxygen index (LOI) of 34.0 % and a UL-94 V-0 rating, and the total heat release (THR) and peak heat release rate (PHRR) of EP/DOPO-GL-DCDA-1.5P decreased by 36.6 % and 46.8 %, respectively, compared with those of pure EP. In addition, compared with those of pure EP, the tensile strength, impact strength, fracture toughness (KIC), and fracture energy (GIC) of EP/DOPO-GL-DCDA-1.5P increased by 62.8 %, 69.9 %, 62.9 %, and 99.0 %, respectively. Moreover, EP/DOPO-GL-DCDA had better dielectric properties than pure EP. Under the premise of maintaining transparency, this work provided a promising solution to synchronously improve the flame retardancy, mechanical strength, and toughness of epoxy thermosets.

Quasi-brittle fracture criterion of CFRP with shallow surface scratch based on boundary effect model

This study investigates the quasi-brittle fracture parameters of carbon fiber composites with shallow surface scratches by considering single-layer prepreg thickness as the characteristic composite microstructure. Three-point bending fracture tests were conducted on single-edge notched specimens of various-sized carbon fiber composites. The boundary effect model was employed to establish the relationship between the microstructure and macroscopic mechanical characteristics of carbon fiber composites. The maximum fracture load was used to determine the quasi-brittle fracture characteristics. By employing normal distribution analysis, the tensile strength and fracture toughness of each specimens were determined asft = 453.28 MPa andKIC = 22.2 MPa √ m, respectively. The analysis results exhibited an error of only 0.39 % compared to the least-squares fit, and encompassed almost all discrete points of the specimens within a 95 % reliability range. Using standard laboratory dimensions, fracture intervals for different notched depths at the same thickness can be predicted. Furthermore, the fracture parameters demonstrated an increasing trend within a certain range as the crack-thickness ratio increases, which aligns with the theoretical findings.

Degradation of the mechanical properties of NbMoTaW refractory high-entropy alloy in tension

The mechanical properties of the bcc refractory high-entropy alloy (RHEA) NbMoTaW with columnar and equiaxed microstructures and a nanoscale metal oxide layer on the grain boundaries are investigated at ambient temperatures (RT) to 1200 °C. Under compression, the alloy shows a yield strength, σy, of ⁓1390 ± 20 MPa at RT and retains a high yield strength, σy, of ⁓301.5 MPa at 1200 °C. However, in tension, the fracture strengths, σf, of both columnar and equiaxed microstructures are far lower - below 70 MPa - and the material fails in the elastic regime without showing any measurable ductility at all temperatures. The fracture mechanisms in tension transition from transgranular cleavage at RT to a mixture of transgranular and intergranular fracture at 800 °C to a complete intergranular fracture at 1200 °C due to selective weakening of the metal oxide layer on the grain boundaries driven by a structural change. The transition in the fracture mechanism in the equiaxed microstructure promotes extrinsic toughening at higher temperatures, resulting in a ⁓6.4 times higher fracture toughness (KIc ⁓10.3 MPa√m) at 1200 °C compared to that at RT. NbMoTaW is a well-known RHEA, but the poor tensile strength and fracture toughness measured in this study highlight the critical importance of investigating the mechanical properties of these high-temperature RHEAs in tension.

Effect of aging temperatures on the microstructure and mechanical properties of TC21 forgings with basket–weave microstructure

This study aims to explore the influence of various aging temperatures on the microstructure and mechanical properties of TC21 forgings. Basket-weave microstructures were prepared via quasi-β forging followed by annealed at 900 °C for 1.5 h and aged at 530 °C, 560 °C, and 590 °C for 4 h, and then their tensile performance, impact toughness, and fracture toughness were examined. Results indicate that higher aging temperatures not only facilitate the segregation of Al element, resulting in a reduction in the effective size (dαlaths, the width/length ratio) of primary α laths (αlaths) and their amount, but also promote phase transition, inducing an increase in the effective size (dαfine) of secondary fine α (αfine) lamellae. While both dαlaths−1/2 and dαfine−1/2 have a linear relationship with the strength, which was analyzed using the Hall–Petch relationship, the more pronounced interface strengthening effect and hindering crack propagation mainly results from the αlaths. Moreover, the plasticity declines significantly as the proportion of the αlaths phases decreases. Thus, for strength and plasticity, the αlaths are a much more important factor than the αfine lamellae. However, although the synergistic deformation and fracture of both the αlaths and αfine phases can consume a larger impact initiation energy, the enhancement of the impact energy of the alloy is primarily related to a high precipitation amount of the αfine lamellae. Furthermore, the decrease in dαlaths promotes the misorientation and accumulation of dislocations between αlaths interfaces, hindering the enhancement of KIC (fracture toughness) by forming transgranular fractures. Conversely, the increase in KIC attributed to the energy consumed in the plastic deformation region at the crack tip, due to the αfine lamellae compensates for the energy, resulting in a reduction in the crack propagation path. Therefore, the αfine lamellae may play a more crucial role in increasing the toughness of alloys, in particular the impact toughness of the TC21 alloy.

Development of a novel characterization model for innovative bionic helical carbon fiber tows

The design of bionic helical structures significantly enhances load-bearing capacity and impact resistance, demonstrating great potential for mechanical property improvement. However, there is still a lack of precise characterization models for the helical structures of carbon fibers, which constrains their potential in engineering applications. This paper successfully fabricated helical carbon fiber tows using a carbon fiber twisting technique and introduced a novel intersecting circular cross-section model to thoroughly investigate the influence of the helical structure on the mechanical properties of carbon fiber tows. Tensile test results show that at a twist angle of 5°, the helical structure increases the tensile strength and fracture toughness of carbon fiber tows by 13.6% and 34.3%, respectively. Additionally, the introduction of complex structures such as helices significantly influences the material’s modulus, and precise modulus prediction is crucial for material optimization and practical application. Based on the newly proposed model, a modulus prediction model is developed, demonstrating higher predictive accuracy than traditional models with a prediction error of 2.8%. Finite element simulations further validate the practicality and superiority of the intersecting circular cross-section model. Compared to traditional models, the predictions of the novel model are closer to experimental data, with a prediction error below 2%, emphasizing the significant impact of microstructures on macroscopic properties and offering a new perspective for modeling complex material systems. These findings provide crucial theoretical and methodological support for the design and performance optimization of carbon fiber materials.

Basalt Fibre-Reinforced Polymer Laminates with Eco-Friendly Bio Resin: A Comparative Study of Mechanical and Fracture Properties.

Fibre-reinforced polymers (FRPs) are widely used in industry due to their impressive strength-to-weight ratio, corrosion resistance and high durability. One of the primary components of FRPs is synthetic resins, specifically epoxy, which has been identified as harmful to the environment. To address this concern, an eco-friendly alternative made from basalt fibres and bio resin has the potential to reduce the environmental impact. This study investigates Basalt Fibre-Reinforced Polymer (BFRP) laminates manufactured using two bio resins, AMPRO™ BIO and Change Climate, comparing them to one conventional epoxy resin, WEST SYSTEM®, in terms of tensile modulus, strength and fracture toughness, as well as shear properties. The results indicate that BFRP laminates made with bio resins exhibit comparable or better mechanical properties to their conventional counterparts with tensile strength being between 6 and 17% more in bio resins compared to the conventional resin, thereby paving the way for further exploration of sustainable FRP laminates in future engineering applications.

The Effect of Chopped Carbon Fibers on the Mechanical Properties and Fracture Toughness of 3D-Printed PLA Parts: An Experimental and Simulation Study

The incorporation of fiber reinforcements into polymer matrices has emerged as an effective strategy to enhance the mechanical properties of composites. This study investigated the tensile and fracture behavior of 3D-printed polylactic acid (PLA) composites reinforced with chopped carbon fibers (CCFs) through experimental characterization and finite element analysis (FEA). Composite samples with varying CCF orientations (0°, 0°/90°, +45°/−45°, and 0°/+45°/−45°/90°) were fabricated via fused filament fabrication (FFF) and subjected to tensile and single-edge notched bend (SENB) tests. The experimental results revealed a significant improvement in tensile strength, elastic modulus, and fracture toughness compared to unreinforced PLA. The 0°/+45°/90° orientation exhibited a 3.6% increase in tensile strength, while the +45°/−45° orientation displayed a 29.9% enhancement in elastic modulus and a 29.9% improvement in fracture toughness (259.12 MPa) relative to neat PLA (199.34 MPa√m). An inverse correlation between tensile strength and fracture toughness was observed, attributed to mechanisms such as crack deflection, fiber bridging, and fiber pull-out facilitated by multi-directional fiber orientations. FEA simulations incorporating a transversely isotropic material model and the J-integral approach were conducted using Abaqus, accurately predicting fracture toughness trends with a maximum discrepancy of 8% compared to experimental data. Fractographic analysis elucidated the strengthening mechanisms, highlighting the potential of tailoring CCF orientation to optimize mechanical performance for structural applications.

Various Morphologies of Graphitic Carbon Nitride (g-C3N4) and Their Effect on the Thermomechanical Properties of Thermoset Epoxy Resin Composites.

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

Serrated flow stress in the CoCrFeNi multi-principal element alloys with different grain sizes and added Re

Multi-principal element alloys have attracted extensive attention as a new alloy design concept. In particular, the CoCrFeNi alloys with low stacking fault energy have excellent tensile plasticity and fracture toughness at both low and room temperature, and good phase stability at high temperatures, considered a new type of structural material with great potential. Multi-principal element alloys exhibit plastic instability termed serrated flow, at certain strain rates and temperature ranges. The serrated flow stress is usually closely related to dynamic strain aging, which reflects dislocation and barrier processes and impacts the mechanical properties of alloys. In the present study, CoCrFeNi alloys were selected as the research object, and the impact of grain size and the addition of Re elements on the serrated flow stress behavior was investigated. The results showed that in the tensile tests at 600 °C, the serrated flow stress behavior occurred in the fine-grain specimen only at a lower strain rate. The tensile curves of the coarse-grain specimen at different strain rates all show serration. Overall, the serrated type changes with the decreasing grain size, the increasing strain rate, and the addition of Re element, all of which result in a decrease in the magnitude and number of serrations and a weakening of the serrated behavior.

Functionalization of calcium-deficient nanohydroxyapatite improves the mechanical properties of 3D printed biopolymer nanocomposites

Agglomerations of nanoparticles in a polymer matrix can drastically reduce the mechanical properties of a polymer nanocomposite, especially its strength. The grafting of nanoparticle surfaces with suitable functional groups can provide improved dispersion and stronger interfacial bonding, improving the fracture resistance of the nanocomposite. In this study, calcium-deficient nanohydroxyapatite (nHA) particles were functionalized with an amino acid-based urethane methacrylate (lysine urethane methacrylate, LUM) and subsequently reacted with hydroxyethyl methacrylate. We mixed these functionalized nHA particles with resin, composed of methacrylated acrylated epoxidized soybean oil, methacrylated isosorbide, and triethylene glycol dimethacrylate, and 3D-printed nanocomposites using masked stereolithography. We hypothesized that the functionalized nanoparticles would enhance the mechanical performance of the 3D-printed nanocomposites due to the greater dispersion and stronger interface. Flexural, tensile, compression and Mode-I fracture toughness test specimens were fabricated using a mSLA printer and tested following ASTM standards. The LUM functionalization of nHA improved the dispersion and increased the viscosity of the uncured nanocomposite ink. The flexural fracture strength, yield strength, and mode-I fracture toughness values were increased by 10 %, 30 %, and 11 %, respectively. The LUM improved the strength and fracture toughness by providing a stronger, more stable interface, resisting debonding between the matrix and particles, allowing for greater plastic deformation.

Enhancement of tensile strength and fracture toughness characteristics of banana fibre reinforced epoxy composites with nano MgO fillers

Natural fibre reinforced polymer composites have drawn the attention of researchers in the creation of novel materials suitable for industrial applications. These polymer composites have favourable mechanical characteristics. Epoxy polymer's versatility and diversity make it suitable for a wide range of industrial applications. The mould casting technique approach was utilised in this work to develop polymer composites using alkali-treated banana fibres and filled with MgO nanoparticle. The study was conducted on the characteristics of Nano MgO, as well as its mechanical qualities such as fracture toughness and surface morphology. The incorporation of Nano MgO enhanced the fracture toughness of the polymer composites with the addition of 1 % MgO. The scanning electron microscopy analysis of the surface morphology revealed the presence of brittle fracture in the specimen.

Modeling and evaluation of the fracture resistance of alkali-resistant glass fibre reinforced concrete under different loading rates

Alkali-resistant glass fibre reinforced concrete (AR-GFRC) has garnered significant interest due to its economic and environmental friendliness. Given the critical importance of evaluating the crack resistance of AR-GFRC under dynamic loading conditions and the size effect inherent in determined fracture parameters using traditional methods, this study aims to propose an analytical approach based on the boundary effect model. The goal is to predict the realistic dynamic tensile strength (ft) and fracture toughness (KIC) while elucidating the rate sensitivity of fracture resistance. Three-point bending tests were conducted on AR-GFRC with three different fibre volumes to investigate dynamic fracture behaviors under varying loading rates. By introducing discrete parameter and the microstructure characteristic parameter that account for material discontinuity and heterogeneity, the realistic dynamic ft and KIC of AR-GFRC can be directly obtained as closed-form solutions upon determining the maximum fracture load from the tests. The results revealed a substantial increase in ft and KIC with an improvement in the loading rate. However, due to relatively weakened fibre activities, the enhancement of dynamic fracture resistance decreases with the increase in fibre content and loading rate.

Sacrificial hydrogen bonds enhance the performance of covalently crosslinked composite films derived from soy protein isolate and dialdehyde starch

Soy protein films have the advantage of being eco-friendly and renewable, but their practical applications are hindered by the mechanical properties. The exceptional tensile strength and fracture toughness of natural silk stem from sacrificial hydrogen bonds it contains that effectively dissipates energy. In this study, we draw inspiration from silk's structural principles to create biodegradable films based on soy protein isolate (SPI). Notably, composite films containing sodium lignosulfonate (LS) demonstrate exceptional strain at break (up to 153%) due to the augmentation of reversible hydrogen bonding, contrasted to films with the addition of solely dialdehyde starch (DAS). The enhancement of tensile strength is realized through a combination of Schiff base cross-linking and sacrificial hydrogen bonding. Furthermore, the incorporation of LS markedly improves the films' ultraviolet (UV) blocking capabilities and hydrophobicity. This innovative design strategy holds great promise for advancing the production of eco-friendly SPI-based films that combine strength and toughness.

Effect of molybdenum disulfide functionalized multiwalled carbon nanotubes based hybrid on morphology, mechanical and thermal properties of epoxy nanocomposites

AbstractThree‐dimensional molybdenum disulfide (MoS2) functionalized MWCNTs hybrid nanoparticles were synthesized using in‐situ hydrothermal reaction. Two types of hybrids, MoS2/MWCNTs‐1 and MoS2/MWCNTs‐2 with MWCNTs to MoS2 precursor weight ratios 1:2 and 1:1 respectively were prepared with varying degrees of hybridization and the effects of their incorporation on tensile strength and fracture toughness properties of epoxies were investigated. Epoxy/MoS2/MWCNTs‐2 nanocomposites showed exceptional mechanical properties due to their improved dispersion, constrained chain mobility and excellent interfacial interactions. MoS2/MWCNTs‐2 nanocomposites showed maximum improvement of tensile strength by 28.52% at 0.5 wt% nanofiller concentration and the highest improvements in fracture toughness by 172% at 0.2 wt% nanofiller concentration. The excellent enhancement of fracture toughness properties was due to the synergic effect of MoS2/MWCNTs hybrid nanoparticles due to the crack pinning and bifurcation properties of MoS2 nanoparticles along with the pull‐out and crack bridging mechanisms of MWCNTs as observed in morphological analysis of fractures nanocomposites. The incorporation of 0.2 wt% of MoS2/MWCNTs‐2 increased the degradation temperatures of epoxy from 591 to 796°C at 95% weight loss due to the improved physical barrier effect.Highlights MoS2/MWCNTs nanoparticles were synthesized using in‐situ hydrothermal reaction 0.5 wt% MoS2/MWCNTs‐2 incorporated epoxies showed highest tensile strength 0.2 wt% MoS2/MWCNTs‐2 incorporated epoxy composites show improved K1c value Incorporation of MoS2/MWCNTs improved the thermal stability of epoxy Synergistic effect of nanocomposite due to crack pinning, bifurcation & bridging