Epoxy Nanocomposites Research Articles

Effect of Dispersing Agents on the Electrical and Mechanical Performance of GNPs Filled Epoxy Nanocomposite

In this work, graphene nanoplatelets (GNPs) filled epoxy nanocomposites with the addition of different dispersing agents were fabricated using a method combines mechanical mixing and tip sonication. The loading of GNPs used is 0.8 vol% determined previously as the amount required to achieve the percolation threshold to conduct electricity. Three dispersing agents were used in this work: Sodium dodecyl sulphate (SDS), ethanol and Phenyl glycidyl ether (PGE), with loadings varying from 2 vol% to 10 vol%. The incorporation of dispersing agent enhanced the electrical bulk conductivity of GNPs filled nanocomposites. The mechanical performance (flexural properties and fracture toughness) of the nanocomposite were evaluated and compared. The optimum loading of SDS to obtain the highest flexural strength and fracture toughness is 2 vol%, where further increases will deteriorate the performance of nanocomposites. On the other hand, the optimum loading of ethanol and PGE are 4 vol%. The fracture toughness of GNPs filled nanocomposites improved with the addition of 2 vol% SDS and deteriorated with increasing loadings of SDS up to 10 vol%. By incorporating 4 vol% of ethanol, the optimum fracture toughness of the nanocomposite is achieved. Fracture toughness is then dropped with further increases in ethanol. The addition of PGE caused deterioration in fracture toughness of GNPs filled epoxy nanocomposite.

Influence of silane and polyethylene glycol functionalization of boron nitride nanosheets on mechanical and thermal properties of epoxy nanocomposites: Machine and deep learning forecasting

AbstractThe influence of hexagonal boron nitride (hBN) nanosheet surface modification on epoxy nanocomposites' mechanical and thermal properties were investigated. An innovative approach was developed for synthesizing hBN nanosheets (hBNNs) via optimized ultrasonic‐assisted liquid‐phase exfoliation (UALPE), followed by functionalization with 3‐aminopropyltriethoxysilane (APTS) and polyethylene glycol (PEG600) for nanocomposite preparation. Compared to unmodified epoxy, nanocomposites containing 0.3 wt% of pristine hBNNs exhibited significant enhancements in flexural strength (125.28 MPa) and tensile strength (53.35 MPa), with respective increases of 40.57% and 43.23%. PEG‐hBNNs improved flexural and tensile strengths to 136.83 and 58.57 MPa, respectively. The most substantial enhancements were observed with APTS‐hBNNs, yielding flexural and tensile strengths of 174.13 and 63.53 MPa, reflecting increases of 95.37% and 70.50%, attributed to better interfacial interactions and a more effective crack deflection mechanism. Thermal stability analyses revealed superior performance of modified hBNNs epoxy nanocomposites, increasing 8.2°C and 6.3°C at 50 wt% degradation as compared to the unmodified system, owing to enhanced physical barrier properties. Structural and morphological analyses validated the successful exfoliation and modification of hBNNs. Predictive models utilizing machine and deep learning (DL) techniques, particularly DL with the adaptive moment estimation (ADAM) optimizer, effectively forecasted mechanical properties, achieving high R2 values.HIGHLIGHTS 0.3 wt% modified hBNNs epoxy nanocomposite showed the highest mechanical strength Improved thermal stability of epoxy nanocomposite by modification of hBNNs Improved crack deflection mechanism in the presence of surface‐modified hBNNs Deep learning with ADAM optimizer showed high R2 and low prediction loss

Mechanical, Fracture, and Thermal Characterization of Post-Cured Hybrid Epoxy Nanocomposites Reinforced with Graphene Nanoplatelets and h-Boron Nitride

The post-curing process of cured composites is essential in enhancing the strength, stiffness, elevating the glass transition temperature, and reducing residual stress in polymer thermoset composites. The curing temperature and time are the key factors that affect these properties. In-situ polymerization method was used to prepare composites with varying weight percentages of graphene nanoplatelets (GNP) and hexagonal boron nitride (h-BN) nanofillers (0.1, 0.2, and 0.3 wt% GNP-based composites; 0.3, 0.4, and 0.5 wt% h-BN-based composites; 0.4, 0.5, and 0.6 wt% h-BN+GNP-based composites). The cured composites were post-cured at temperatures of 80°C, 120°C, and 160°C for 120 minutes in a hot air oven. The presence of GNPs and h-BNs in the composites is confirmed using Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Further mechanical and thermal properties were evaluated by conducting tensile, flexural, impact, fracture and differential scanning thermometry (DSC) tests. The simulation analyses were performed using Ansys software, and the results demonstrated a strong correlation with the experimental data, with discrepancies between the two consistently within a standard margin of 20%.

A novel water‐based mechanochemical approach for surface modification of graphene platelets and their epoxy nanocomposites

AbstractGraphene (nano) platelets (GPs) are cost‐effective and possess high structural integrity, but their limited surface functional groups hinder their compatibility with polymers. In this study, an eco‐friendly, water‐based mechanochemical approach was developed to modify GPs with polyacrylamide (PAM), creating PAM graphene platelets (PAM‐GPs) with a grafting ratio of approximately 15%. The platelet was measured to be a few nanometers in thickness, and the grafted PAM provides abundant functional groups, including amide groups, which enhance compatibility with polymers. A typical polymer, bisphenol‐A epoxy, was compounded with PAM‐GPs, resulting in a high degree of exfoliation and dispersion of PAM‐GPs within the matrix. The resulting epoxy/PAM‐GP composites exhibited significantly improved mechanical properties, including an 18% increase in Young's modulus and a substantial enhancement in fracture toughness, with a 71% increase at a low filler fraction of 0.5 wt%. These improvements are attributed to the effective interfacial interaction between the PAM‐GPs and the epoxy matrix, facilitated by the grafted functional groups. This study highlights the potential of PAM‐GPs as toughening fillers for epoxy composites, emphasizing their applicability in enhancing the durability and performance of structural components in industrial applications.Highlights Polyacrylamide (PAM)‐modified graphene platelets by a water‐based approach. A strong interface promoted exfoliation and dispersion of platelets. PAM‐modified platelets improved epoxy modulus and toughness. Fractographic analysis unveils toughening mechanisms.

Joule debonding of carbon reinforced polymer (CFRP) lap shear joints bonded with graphene nanoplatelets (GNPs)/epoxy nanocomposites

The potential of Joule heating CFRPs joints bonded with conductive graphene/epoxy nanocomposites as adhesives for a selective debonding was investigated. To ensure a localized softening of the bondline without altering the adherend’s structure, the epoxy used in the adhesive’s formulation was chosen to have a considerably lower Tg than the adherend. Joule heating the bondline considerably reduced the lap shear strength (LSS) relative to when the test was performed at room temperature, due to thermally induced structural changes promoted in the polymer network, which was consistent with the nanocomposites’ thermomechanical behavior predicted by DMTA. The minimum LSS value was reached in the vicinity of the adhesive’s Tg, allowing an ease deconstruction of the joints. SEM characterization of their fracture surfaces revealed that by controlling the adhesive’s formulation and their Joule heating the joints’ failure mechanism can be tuned to ensure the recovery of undamaged adherends that can be reused.

Epoxy microlattice with simultaneous self-sensing and electromagnetic interference shielding performance by in-situ additive manufacturing

The development of epoxy nanocomposite architectures capable of self-sensing the internal structural response to mechanical stimuli and exhibiting multifunctionality represents a significant challenge to the scientific community. Here, an in-situ additive manufacturing technique is developed to construct robust SiO2/epoxy host material and piezoresistive nanocarbon/epoxy sensing elements into an engineered 3D microlattice. The integration of microscale sensing elements with tailored embedment locations and contents enables the real-time detection of in-situ strain under varying loadings, without compromising the mechanical properties of the original host structure. Additionally, the epoxy microlattices containing 3D interconnected network of sensing elements present excellent electromagnetic interference shielding properties, attaining a high shielding effectiveness of up to 33 dB. Furthermore, the applications of the epoxy microlattice in defect-recognizable composite lattices and multifunctional protective devices are demonstrated. The present findings suggest an effective strategy for the development of intrinsically smart epoxy nanocomposites with customized microstructure and unprecedented multifunctionality.

Enhancing wind turbine blade protection: Solid particle erosion resistant ceramic oxides-reinforced epoxy coatings

Wind energy has been regarded as one of the renewable energy sources to rely on in the future. In this aspect, wind turbine blade maintenance is quite a challenge in tropical areas like India. One of the main reasons why wind turbine blades get damaged and produce less energy is solid particle erosion. In the present work, nanocomposite epoxy (EP) coatings reinforced with Al2O3, ZrO2, and CeO2 nanoparticle fillers have been applied on glass fiber reinforced polymer (GFRP) substrates using a simple spray coating method. These nanoparticles have been prepared in-house by solution combustion synthesis (SCS) route using urea, glycine, and oxalyl dihydrazide fuels. X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy have been used to characterize the materials and coatings. EP coatings with different Al2O3, ZrO2, and CeO2 nanoparticle concentrations have been subjected to solid particle erosion resistance tests at impinging angles of 30°, 60° and 90°. ZrO2 and CeO2 nanoparticle-reinforced EP coatings show better resistance to solid particle erosion than Al2O3-reinforced coatings. Estimated average erosion rates are 17 and 11.3 × 10−3 mm3 g−1, respectively, for epoxy coatings with 20 and 40 wt% ZrO2 nanoparticles. However, GFRP substrate and neat EP coating show much higher erosion rates with respect to nanoparticles-reinforced EP coatings. To ascertain a correlation between H3/E2 and the solid particle erosion rates of the coatings, nanoindentation tests have been carried out. Tensile strength and initial modulus of all the coatings are found to be directly proportional to the average erosion rates, whereas, elongation at break shows an inverse relationship with the average erosion rate. This correlation of mechanical properties with solid particle erosion performance can play a critical role in the development of realistic simulation of protective coatings for wind turbine blades.

Shielding characteristics of a new epoxy resin reinforced by PbO nanoparticles and PbO micro for protection against X-ray and investigation of their cytotoxicity effects and photocatalytic activity

In this research, for the first time, lead oxide nanoparticles (PbO-NPs) were synthesized using Trigonella feonumgraecum plant seeds as a stabilizer and Pb (NO3)2 salt as lead precursor. The results of the XRD pattern displayed the synthesized NPs have an orthorhombic crystalline structure. According to FESEM images, the NPs had a mean size of about 18.62 nm with a spherical morphology. Also, the cytotoxicity of NPs was evaluated on the Hep G2 cancer cell line, and the IC50 value was reported as 267.07 μg/mL. Next, the photocatalytic performance of the synthesized PbO-NPs was investigated for removing methylene orange (MO) pigment under UVA light, which led to the destruction of about 94% after 120 min. Finally, to investigate the protective property of PbO-NPs against X-ray, a polymer nanocomposite of epoxy resin/PbO-NPs was prepared with different weight percentages. In the same way, other samples were also prepared, and then their ability to attenuate X-ray was studied with an X-ray tube with a voltage of 52 kV for the palm and 80 kV for the thigh of an average person, respectively. The measurement results show that with the increasing weight percentage of the fillers, the samples' linear and mass attenuation coefficient increases, which means an increase in the efficiency of the samples in X-ray attenuation. Generally, epoxy resin/PbO-NPs samples show a better effect than other samples. Therefore, these types of shields can attract more attention due to their lightness, cost-effectiveness, and far fewer environmental hazards than common lead shields.

Functionalization of boron nitride with poly(catechol-polyamine) and bis(γ-triethoxysilylpropyl)tetrasulfide for preparing epoxy nanocomposites with enhanced thermal conductivity

Hexagonal boron nitride (hBN) has garnered significant interest as inorganic thermally conductive material in electronic packaging due to its high-efficiency thermal management capability and electrical insulation properties. However, the relatively inert chemical environment of the BN surface hinders phonon transfer at the interface. Additionally, the high content of inorganic components in the matrix leads to the deterioration of the composite’s mechanical properties. In this research, h-BN surface is modified using poly(catechol-polyamine) (PCPA) and bis (γ-triethoxysi-lylpropyl)tetrasulphide (Si69) (denoted as BN-PCPA-Si69). The noncovalent PCPA modification protects the endothermic properties of BN, Si69 provides covalent bonding between thermally conductive fillers and bisphenol A-type epoxy resin (Ep), and the interfacial compatibility between BN and epoxy resin is improved. The heat conductivity of final BN/Ep composite achieved 0.817 W/(m·K) containing 30 wt% BN. Correspondingly, the heat conductivity of the composite (mBN/Ep) achieved 0.881 W/(m·K) containing 30 wt% BN-PCPA-Si69. Compared to pure epoxy resin (0.200 W/(m·K), the thermal conductivity (TC) of the mBN/Ep composite increased by 364% while maintaining good electrical insulation properties. The proposed BN surface functionalization approach has potential applications in fields such as microelectronic packaging, where materials need to balance high thermal conductivity and electrical insulation.

Environmentally Benign High‐Performance Composites‐Based Hybrid Microcrystalline Cellulose/Graphene Oxide

ABSTRACTA novel silane functionalization prepared by a solution mixing approach of epoxy composites filled with eco‐friendly reinforcement filler, that is, graphene oxide (GO) and microcrystalline cellulose (MCC). The developed composites were subjected to comprehensive analysis using various characterization techniques, encompassing mechanical testing, water absorption analysis, thermal stability assessment, and scanning electron microscopy (SEM). The tensile strength and Young's Modulus of the epoxy composite filled with 1.0 wt.% of GO (EGO1.0) demonstrated the highest value viz. 29.83 MPa and 1991.71 MPa, respectively, when compared to neat epoxy composite (E0). Meanwhile, the thermal gravimetry analysis (TGA) studies, particularly char yield, highlight improvements in the thermal stability of the EGO2.5 composite, that is, 23.39% representing a 33.73% increment compared to the E0 composite. The synergistic effect of hybrid filler, achieved by a combination of micro and nanoparticle fillers within an epoxy matrix, was investigated as a virtuous alternative to the conventional epoxy nanocomposites. A uniform dispersion of GO on the MCC surface leads to significant improvements in the mechanical properties and thermal stability of the epoxy‐reinforced composite. The maximum tensile strength, Young's Modulus, and break strain of 39.77 MPa, 2591.27 MPa, and 2.90%, respectively, were observed for the modified EGO1.0MCC1.5 composite. The synergistic effect of hybrid eco‐friendly reinforcement fillers (GO/MCC) and a strong interfacial adhesion between the matrix and filler reduces the formation of defects, thereby resulting in good stress transfer from matrix to fillers.

The Role of Silanization of Barium Strontium Titanate Nanopowders on the Dielectric Constant and Thermal Stability of Epoxy Nanocomposites

AbstractThis paper reports polymer composites′ microstructure and dielectric properties based on an epoxy resin matrix containing different amounts (from 2–10 wt. %) of barium strontium titanate nanoparticles. (Ba,Sr)TiO3 was prepared using the hydrothermal method, showing an average particle size of 100 nm. The composites′ thermal properties and morphology were characterized using thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. Our studies show that the (Ba,Sr)TiO3 nanoparticles were well dispersed in the epoxy resin matrix thanks to controlled silane functionalization. Accordingly, the glass transition temperature (Tg) value of the nanocomposites was found to be 159.0 °C at 10 wt. % (Ba,Sr)TiO3 loading and is higher than the neat epoxy resin Tg (Tg=154.7 °C). Moreover, the dielectric composite properties were investigated comprehensively via a wide range of frequencies from 10 Hz to 100 kHz. The results indicate that (Ba,Sr)TiO3 nanopowders and the surface modifying filler play a crucial role in the significant increase of the dielectric constants, approximately 1.5 times at the optimum added amount (Ba,Sr)TiO3. The limited functionalization of (Ba,Sr)TiO3 nanoparticles by the silane affords to control the nanocomposite dielectric loss. Furthermore, the nanocomposites also exhibited good thermal stability.

Fabrication and Tribological Properties of Epoxy Nanocomposites Reinforced by MoS2 Nanosheets and Aligned MWCNTs.

The epoxy nanocomposites reinforced by MoS2 nanosheets and aligned multi-walled carbon nanotubes (MWCNTs) were fabricated by DC electric field inducement. The epoxy nanocomposites achieved improvement in the tribological properties with the addition of randomly dispersed MoS2 and MWCNTs compared to the pure epoxy. Furthermore, the epoxy nanocomposites exhibit anisotropic tribological and mechanical properties when the MWCNTs are aligned in the composites. The tribological properties of epoxy nanocomposites containing 1 wt% MoS2 and aligned 1.2 wt% MWCNTs achieved the maximum improvement when the sliding direction is perpendicular to the axial direction of MWCNTs. Compared to random MoS2 nanosheets and random MWCNTs reinforced epoxy nanocomposites, the friction coefficient and wear rate of random MoS2 and aligned MWCNTs reinforced epoxy nanocomposites decreased by 11.3 and 66.7% under a load of 5 N, respectively. The increased thermal conductivity and mechanical properties, higher surface content of nanoparticles, as well as unique alignment mode of MWCNTs are considered to be the main reasons for the improvement of tribological properties of epoxy nanocomposites.

Exploring the potential of epoxy nanocomposites infused with Alq3 for UV sensing applications

This research explores the morphological, molecular, and photoluminescent properties of epoxy-based nanocomposite sheets containing Alq3, as well as their response to UV irradiation. By analyzing the surface morphology via SEM, it is observed that the pristine epoxy sheets exhibit uniformity, while the nanocomposites display dispersed nanoparticles, influenced by the concentrations of dopants. Raman spectroscopy reveals changes in molecular structures and vibrational modes, with broadened peaks indicating potential interactions between the additives and epoxy matrix. The photoluminescence (PL) emission spectra show enhancements in intensity and shifts in peak wavelengths toward the green emission region, significantly influenced by the dopants. UV irradiation causes changes in both Raman and PL signals, with varying effects on different nanocomposite configurations. Linear regression analysis demonstrates strong correlations between signal changes and irradiation time, particularly pronounced in epoxy/Alq3 nanocomposite sheets, with marginal errors from Raman and PL signal-induced changes of 5% and 2%, respectively. Additionally, stability and reproducibility assessments reveal consistent signal trends over prolonged UV exposure and high reproducibility with minimal error of less than 5%. Overall, these epoxy nanocomposite sheets display promising results for UV sensing applications due to their sensitivity, linearity, stability, and reproducibility.

Experimental investigation of the compressive behavior of epoxy nanocomposites reinforced with straight and helical carbon nanotubes

AbstractThis paper is aimed at an experimental investigation of the effect of straight and helical carbon nanotubes on the compressive behavior of epoxy nanocomposites. The epoxy nanocomposites are fabricated with varying levels of SCNT and HCNT, each with two different fabrication techniques viz. high shear mixing and ultrasonication. In samples made using high shear mixing, the compressive strength is found to actually decrease, due to poor dispersion of the CNTs, resulting in voids and clumps, which can adversely affect the strength. Ultrasonic homogenization is found to better disperse the CNTs within the epoxy resin with nearly a 10‐fold decrease in the heterogeneity size. Compression tests conducted on the ultrasonically homogenized CNT‐epoxy nanocomposites indicate a modest increase in the compressive strength. The best increase of 5% is obtained with 1% SCNT. On the other hand, the HCNT samples show a higher post‐peak residual stress suggesting an improved mode II/III fracture toughness. The high shear mixed samples exhibit a bulging deformation with no clear evidence of shear localization. On the other hand, the ultrasonic homogenization (UH) samples bulge and eventually show a clear localized shear band, likely due to a smaller heterogeneity size. Some samples with relatively poor dispersion exhibit an axial splitting failure and a comparatively low compressive strength. In addition, it is demonstrated that using acetone as a solvent during dispersion can affect the curing kinetics, which results in a nanocomposite with a rubbery consistency with low stiffness and strength, but high deformability.Highlights Straight and helical CNTs impact the compressive behavior of epoxy nanocomposites High shear mixing reduces compressive strength due to poor CNT dispersion Ultrasonication improves CNT dispersion but modest rise in compressive strength HCNTs cause higher post‐peak residual stress suggesting higher toughness Using acetone affects curing, leading to rubbery, deformable nanocomposites.

MOLECULAR MECHANISM OF PHYSICAL AND MECHANICAL IMPROVEMENT IN GRAPHENE/GRAPHENE OXIDE-EPOXY COMPOSITE MATERIALS.

The performance provided by graphene (Gr) and graphene oxide (GO) additives can be improved by achieving strong adhesion and uniform dispersion in the epoxy resin matrix. In this study, molecular modeling and simulation of DGEBA/DETA based epoxy nanocomposites containing Gr and GO additives were performed. Density functional theory and molecular dynamics simulations were used to investigate interfacial interaction energies and Young's Modulus. Improvement in the interaction energies was studied by controlling the epoxy:hardener ratio, type and the number of oxygen-containing functional groups on the GO, the mass percentage of Gr/GO filler in the epoxy matrix, size and dispersion of GO in the cell. It was demonstrated that functional groups with up to 10% oxygen content in GO significantly increase interfacial interaction energy for large size Gr/GO. Increasing DETA type amine ratio in the preparation of epoxy polymers increases the interaction energy for high oxygen content while decreasing the interaction energy for low oxygen content in GO for small size GO with edge functional groups. The performance of material dramatically decreased even at high DETA hardener and high GO mass percentages when the aggregation factor of Gr/GO was included in simulations that explain lower Gr/GO percentages in the experimental studies.

Analysis of the impact of exfoliated graphene oxide on the mechanical performance and in-plane fracture resistance of epoxy-based nanocomposite

Graphene oxide (GO) is a versatile material, derivative of graphene, and it has gained significant attention in the field of polymer nanocomposites due to its exceptional properties and unique structural features. These characteristics make it a successful secondary reinforcing agent for enhancing mechanical performance, fatigue resistance, and other various physical and thermal properties of nanocomposites. However, the low fracture toughness of nanocomposite has restricted the overall structural applications. In this research work, the epoxy nanocomposites were prepared with different weights of exfoliated graphene oxide (E-GO) nanoparticles by using a dual mixing probe ultra-sonication for homogeneous distribution and proper dispersion. A substantial enhancement in mechanical performance and fracture toughness of nanocomposite was observed. The good dispersion and interfacial adhesion among E-GO and epoxy matrix were investigated through the critical analysis of the fracture surfaces of the nanocomposite. The enhancement of mechanical performance of E-GO nanofiller-reinforced epoxy composite was observed superior at 1 wt. % of GO60 particle concentration. The maximum increment of mechanical properties such as tensile strength, flexural strength, and work of fracture were 40.763, 39.23, and 12.106 % respectively, whereas maximum tensile modulus and flexural modulus were 19.3724, 27.63 % at 1.5 wt. % of GO60 as compared to the neat composite. However, in the case of fracture toughness and energy, maximum improvement of 1.256 Mpa.m1/2 and 0.472 KJ/m2 respectively was observed at 1 wt. % of GO60. Such enhancement was primarily due to the bolstering of in-plane crack propagation resistance in the nanocomposites. Additionally, the highlight point in thermomechanical properties of the polymer nanocomposite is optimal storage modulus and damping factor such as 4066.75 MPa, and 0.46 respectively, for the GO60 at 1 wt.% nanocomposite. Moreover, GO60 at 1 wt.% demonstrates greater thermal stability, withstanding up to 50% material degradation at 413.65°C.

Thermal, mechanical, and morphological properties of oil palm cellulose nanofibril reinforced green epoxy nanocomposites

In this study, significant improvements in mechanical properties have been seen through the efficient inclusion of Oil Palm Cellulose Nanofibrils (CNF) as nano-fillers into green polymer matrices produced from biomass with a 28 % carbon content. The goal of the research was to make green epoxy nanocomposites utilizing solution blending process with acetone as the solvent with the different CNF loadings (0.1, 0.25, and 0.5 wt%). An ultrasonic bath was used in conjunction with mechanical stirring to guarantee that CNF was effectively dispersed throughout the green epoxy. The resultant nanocomposites underwent thorough evaluation, comparing them to unfilled green epoxy and evaluating their morphological, mechanical, and thermal behavior using a variety of instruments. Field-emission scanning electron microscopy (FE-SEM) was used to validate findings, which showed that the CNF were dispersed optimally inside the nanocomposites. The thermal degradation temperature (Td) of the nanocomposites showed a marginal decrement of 0.8 % in temperatures (from 348 °C to 345 °C), between unfilled green epoxy (neat) and 0.1 wt% of CNF loading. The mechanical test results, which showed a 13.3 % improvement in hardness and a 6.45 % rise in tensile strength when compared to unfilled green epoxy, were in line with previously published research. Overall, the outcomes showed that green nanocomposites have significantly improved in performance.

Optimizing DMF Utilization for Improved MXene Dispersions in Epoxy Nanocomposites

Optimizing DMF Utilization for Improved MXene Dispersions in Epoxy Nanocomposites

Fracture modeling of CNT/epoxy nanocomposites based on phase-field method using multiscale strategy

The computational modeling of fracture, particularly in structures with complex crack topologies, remains challenging due to significant computational costs, especially in simulating two- and three-dimensional brittle fracture. This study presents an efficient phase-field model to address these challenges. By leveraging the user (UMAT) subroutine in ABAQUS and establishing an analogy between the phase-field evolution law and the heat transfer equation, the method efficiently tackles complex fracture problems. The model is verified through analysis of typical 2D and 3D fracture benchmarks with different failure modes, demonstrating accuracy and efficiency compared to experimental and numerical data. Additionally, the model is applied to explore brittle fracture in carbon nanotubes (CNTs)/epoxy nanocomposites, revealing insights into the impact of CNT weight fraction on fracture phenomena prediction. The incorporated CNTs in the matrix are considered uniformly dispersed and randomly oriented. Overall, the developed model and computational implementation show promise for meeting the requirements of structural-level engineering practices.

Simultaneous improvement in the elastic and fracture properties of graphene-epoxy nanocomposites–a computational perspective

The incorporation of stiff nano-additives (such as graphene) into a relatively soft polymer material (such as epoxy) usually leads to an improvement in elastic properties (i.e., Young's modulus) at the expense of fracture properties (i.e., tensile strength and toughness). Despite over a decade of research in polymer nanocomposites, we still lack a clear understanding of their structure-property relationships, which limits us from enhancing both elastic and fracture properties concurrently. Here, we performed large-scale reactive molecular dynamics simulations to study the deformation and fracture of model graphene/epoxy systems under uniaxial tension. A computationally efficient reactive force field was developed for graphene-epoxy system, allowing covalent bond formation, and breaking, which is crucial to model cross-linking in model epoxy as well as fracture. It was found the mechanical properties of the nanocomposite are very sensitive to the strength of the graphene-epoxy interface. As expected, elastic modulus increases with the interfacial strength. However, there appears to be an optimal interfacial strength to enhance the tensile strength and toughness. This is due to stress concentration occurring near the graphene edges at high interfacial strength, which leads to premature fracture. We show that by appropriately selecting an intermediate interface strength, one can simultaneously improve the ultimate tensile strength, toughness and the Young's modulus of the nanocomposite epoxy at ultra-low (∼0.2 % by weight) loading fraction of graphene additives. Our findings highlight the critical importance of properly engineered additive-matrix interfacial strength to develop high-performing polymer nanocomposites that are concurrently stiff, strong as well as tough.