Incorporation Of Graphene Nanoplatelets Research Articles

Effect of different nanofillers incorporation on HDPE/LDPE films nanocomposite

The objective of this study was to develop polymeric films of high-density polyethylene (HDPE)/low-density polyethylene (LDPE) that comprise 1 wt% of different nanofillers, that is, either nanofibrillated cellulose (NFC), montmorillonite clay (MMT), or graphene nanoplatelets (GNPs); the polymeric films were developed with and without the inclusion of a coupling agent (CA). The results indicated that all the samples that comprised nanofillers exhibited, at least, an increase of 3 to 25°C compared with that of the matrix and demonstrated higher stability at the beginning of the thermal degradation, as verified using TGA. In the DSC analysis of the samples that contained GNPs had highest crystallinity index (55%), having as the consequent improvement in the mechanical properties and in the oxygen permeation. The incorporation of GNPs provided a 127.71% increase in deformation at break and a lower value in oxygen permeability with 50.06 mL.cm.(cm2.s.cmHg)−1, when compared to the polymeric matrix. It was concluded that all the different nanofillers tested promoted distinct improvements in HDPE/LDPE films nanocomposite. It can be inferred that these modifications are related to the chemical composition, size and morphology of each nanofiller. Thereby, it is indicated that with the use of each nanofiller one must be in accordance with the necessary demand of each composite film.

Predicting the properties of concrete incorporating graphene nano platelets by experimental and machine learning approaches

Modern infrastructure requirements necessitate structural components with improved durability and strength properties. The incorporation of nanomaterials (NMs) into concrete emerges as a viable strategy to enhance both the durability and strength of the concrete. Nevertheless, the complexities inherent in these nanoscale cementitious composites are notably intricate. Traditional regression models face constraints in comprehensively capturing these intricate compositions. Thus, posing challenges in delivering precise and dependable estimations. Therefore, the current study utilized three machine learning (ML) methods, including artificial neural network (ANN), gene expression programming (GEP), and adaptive neuro-fuzzy inference system (ANFIS), in conjunction with experimental investigation to study the effect of the integration of graphene nanoplatelets (GNPs) on the electrical resistivity (ER) and compressive strength (CS) of concrete containing GNPs. Concrete containing GNPs demonstrated an improved fractional change in resistivity (FCR) and strength. The experimental measures depict that strength enhancement was notable at GNP concentrations of 0.05% and 0.1%, showcasing increases of 13.23% and 16.58%, respectively. Simultaneously, the highest observed FCR change reached −12.19% and −13%, respectively. The prediction efficacy of the three models proved to be outstanding in forecasting the characteristics of concrete containing GNPs. For CS, the GEP, ANN, and ANFIS models demonstrated impressive correlation coefficient (R) values of 0.974, 0.963, and 0.954, respectively. For electrical resistivity, the GEP, ANN, and ANFIS models exhibited high R-values of 0.999, 0.995, and 0.987, respectively. The comparative analysis of the models revealed that the GEP model delivered precise predictions for both ER and CS. The mean absolute error (MAE) of the GEP-CS model demonstrated a 14.51% reduction compared to the ANN-CS model and a substantial 48.15% improvement over the ANFIS-CS model. Similarly, the ANN-CS model displayed an MAE that was 38.14% lower compared to the ANFIS-CS model. Moreover, the MAE of the GEP-ER model demonstrated a 56.80% reduction compared to the ANN-CS model and a substantial 82.47% improvement over the ANFIS-CS model. The Shapley Additive explanation (SHAP) analysis provided that curing age exhibited the highest SHAP score. Thus, indicating its predominant contribution to CS prediction. In predicting ER, the graphene content exhibited the highest SHAP score, signifying its predominant contribution to ER estimation. This study highlights ML's accuracy in predicting the properties of concrete with graphene nanoplatelets, offering a fast and cost-effective alternative to time-consuming experiments.

Infusion Simulation of Graphene-Enhanced Resin in LCM for Thermal and Chemo-Rheological Analysis.

The present numerical study proposes a framework to determine the heat flow parameters-specific heat and thermal conductivity-of resin-graphene nanoplatelets (GNPs) (modified) as well as non-modified resin (with no GNPs). This is performed by evaluating the exothermic reaction which occurs during both the filling and post-filling stages of Liquid Composite Moulding (LCM). The proposed model uses ANSYS Fluent to solve the Stokes-Brinkman (momentum and mass), energy, and chemical species conservation equations to a describe nano-filled resin infusion, chemo-rheological changes, and heat release/transfer simultaneously on a Representative Volume Element (RVE). The transient Volume-of-Fluid (VOF) method is employed to track free-surface propagation (resin-air interface) throughout the computational domain. A User-Defined Function (UDF) is developed together with a User-Defined Scaler (UDS) to incorporate the heat generation (polymerisation), which is added as an extra source term into the energy equation. A separate UDF is used to capture intra-tow (microscopic) flow by adding a source term into the momentum equation. The numerical findings indicate that the incorporation of GNPs can accelerate the curing of the resin system due to the high thermal conductivity of the nanofiller. Furthermore, the model proves its capability in predicting the specific heat and thermal conductivity of the modified and non-modified resin systems utilising the computed heat of reaction data. The analysis shows an increase of ∼15% in the specific heat and thermal conductivity due to different mould temperatures applied (110-170 °C). This, furthermore, stresses the fact that the addition of GNPs (0.2 wt.%) improves the resin-specific heat by 3.68% and thermal conductivity by 58% in comparison to the non-modified thermoset resin. The numerical findings show a satisfactory agreement with and in the range of experimental data available in the literature.

Diamino-Substituted Quinones as Cathodes for Lithium-Ion Batteries.

This study introduces a sustainable approach to designing organic cathode materials (OCMs) for lithium-ion batteries as a potential replacement for traditional metal-based electrodes. Utilizing green synthetic methodologies, we synthesized and characterized five distinct quinone derivatives and investigated their electrochemical attributes within Li-ion battery architectures. Notably, the observed specific capacities were lower than the theoretical predictions, suggesting limitations in achieving efficient redox reactions in a coin-cell configuration. Among the quinone derivatives studied, one variant derived from natural vanillin showed superior cycle stability, maintaining 58% capacity retention over 95 charge-discharge cycles, and achieving a Coulombic efficiency of 90%. Importantly, we discovered that the commonly used Super-P conductive carbon did not yield any measurable battery performance; instead, these quinones necessitated the incorporation of graphene nanoplatelets as the conductive matrix. Through a facile one-step synthesis in ethanol or water, we have demonstrated a viable synthetic route for producing OCMs, albeit with moderate performances, which have attempted to address common concerns of high solubility and poor redox reactivity of previous OCMs, thereby offering a sustainable pathway for the development of organic-based energy storage devices.

Effect of graphene nano-platelets on the low-velocity-impact and compression-after-impact strength of the glass fiber epoxy composite laminates

Detecting the low-velocity impact damage on the FRP composite structures can be challenging because the visible signs on the surface may be subtle. Mitigating the effects of BVID (Barely Visible Impact Damage) is crucial in ensuring the safety and reliability of composite components, especially in industries where these materials are commonly used, such as aerospace and automotive. This article explores the experimental investigations of the impact and post-impact damage propagation under compression in the Graphene Nano-Platelets (GNPs) infused glass fiber epoxy composite laminates. A comparative study of varying the percentage of the nano-platelets (0, 0.25, 0.5, and 0.75%) in the matrix material of the composite laminate is presented. The impact tests at low energies (15 J, 20 J, and 25 J), followed by the quasi-static compression tests, are carried out as per the procedures mentioned in the ASTM D7136/D7137. The digital image correlation technique (DIC) is used to measure strains and plot the strain field on the impacted face of the specimen under compression. Damage envelopes of the impact and compression tests are studied using X-ray CT scans. Micro-level failures are observed through Scanning Electron Microscopy (SEM) to get better insights into the failure mechanism of the composite materials under impact and compression loadings. Upon completing the study, it is found that the addition of the GNP into the matrix materials not only increased the impact performance but also increased the load-carrying capacity of the laminate under compressive loading. A decrement of 2–21% in the energy absorbed in the damage formation is seen with the incorporation of GNPs into composite materials. A maximum increment of 17% in the compressive strength is observed for the composite laminates with the 0.75% GNPs. However, for a particular percentage of the GNP, the compressive strength of the laminate is reduced with an increase in impact energy compared with its virgin counterpart. From X-ray CT scans, it is seen that the laminate under the compression tests fails due to excessive ply-splitting and the delamination at the damage site created during the impact. Fiber breakage, fiber brooming, matrix cracking, fiber-matrix debonding, etc., are some of the other failure modes observed in SEM studies.

Influence of adding nanomaterials on shear properties of epoxy resin at different temperatures

Adhesive joints play a vital role in different industries owing to their advantages and ease of application compared to other joining methods. This research focuses on enhancing the mechanical properties of epoxy adhesives by incorporating graphene nanoplatelets (G) and iron-oxide nanofillers (Fe<sub>3</sub>O<sub>4</sub>). Single-lap adhesive joints, including both G and Fe<sub>3</sub>O<sub>4</sub> nanoparticles, are fabricated at 2%, 3%, and 4% weight percentages and tested under tensile load at ambient, 45°C, and 88°C. The results reveal that adding G and Fe<sub>3</sub>O<sub>4</sub> nanofillers enhances shear strength at elevated and room temperatures without altering the epoxy glass transition temperature (Tg). Furthermore, G nanofiller performs better in improving shear strength than Fe3O4. The optimal weight percentage is identified as 3 wt% for G and Fe<sub>3</sub>O<sub>4</sub>, as higher percentages lead to decreased shear strength due to agglomerations. This study provides insight into tailoring epoxy adhesives for improved mechanical performance under varying temperature conditions.

Revolutionizing transportation composite structures: Lightweight, sustainable, and multi-scale hybrid design through waste tire-driven graphene, hemp fiber, and bio-based overmoulding

The pursuit of lightweight, environmentally friendly composite structures in transportation is crucial for minimizing ecological footprints and promoting energy-efficient manufacturing techniques. This study presents a novel approach by replacing traditional long glass fiber reinforced homopolymer polypropylene (homoPP) compounds with short hemp fiber reinforced homoPP, incorporating graphene nanoplatelets (GNP) derived from recovered carbon black via waste tire pyrolysis, resulting in a remarkable 15% weight reduction. With new compound formulation by adjusting the amounts of compatibilizer and GNP, injection moulding process was integrated with overmoulding process by using bio-based UD prepregs to enhance the adhesion of injected part and interfacial interaction by decreasing the stress concentrations in the structure. This novel hybrid composite design having 40 wt% hemp fiber, 1.0 wt% GNP and 2.7 wt% compatibilizer provided to improve flexural modulus and strength by 169% and 67.9%, respectively, compared to neat homoPP. The overmolding process employed bio-based natural fibers reinforced UD tapes as inserts, leading to an impressive enhancement of 211% in tensile modulus and 93.6% in strength, further surpassing the performance of neat homoPP. This work not only achieves the conversion of conventional composite structures into recyclable, sustainable thermoplastic composites but also introduces multi-scale reinforcements with customizable functionality, demonstrating a significant step forward in the development of environmentally conscious materials and manufacturing methods by adopting Life-Cycle Assessment (LCA) methodology regarding the sustainability of the newly developed composites.

Experimental study and ANFIS modelling of the thermophysical properties and efficacy of GNP-Al2O3 hybrid nanofluids of different concentrations and temperatures

This study delves into an extensive investigation of the thermophysical properties and heat transfer efficacy of a hybrid nanofluid incorporating graphene nanoplatelets and γ-Al2O3 nanoparticles dispersed in deionised water. The nanofluids were characterised for their viscosity (µ), thermal conductivity (λ), and electrical conductivity (σ) over a 15–40 °C temperature range for varying nanoparticle loading (0.1–0.4 vol%). The experimental results revealed notable enhancements in µ, λ, and σ with increasing nanoparticle concentration, while µ decreased at elevated temperatures as λ and σ increased. At the highest concentration (0.4 vol%), µ increased by 21.74%, while λ and σ exhibited peak enhancements of 17.82% and 393.36% at 40 °C. An Adaptive Neuro-fuzzy Inference System (ANFIS) model was devised to enhance predictive precision by meticulously optimising the number of membership functions (MFs) and input MF type. The ANFIS architecture that exhibited the most remarkable agreement with the experimental data for µ, λ, and σ was found to utilise the Product of Sigmas, Difference of Sigmas, and Generalized Bell MFs, respectively, with corresponding input MF numbers being 2–3, 3–2, and 3–2. The optimal ANFIS model for µ, λ, and σ exhibits a higher prediction accuracy with an R2 value of 0.99965, 0.99424 and 0.99995, respectively. The Figure of Merit analysis using Mouromtseff Number identified an optimal nanoparticle concentration range of 0.1–0.2 vol% for enhanced heat transfer performance with a reasonable µ increase. This range guides practitioners in utilising hybrid nanofluids effectively while managing potential drawbacks.

Carbon-graphene-epoxy sandwich dielectric for improved dielectric response to humidity

A sandwich structure of carbon-epoxy laminate with graphene nanoplatelets is used for increasing the AC conductivity, dielectric constant and sensitivity towards moisture. The Quasi Fickian distribution of moisture absorption of epoxy is retained with the inclusion of carbon fibers and graphene nanoplatelets of 1 weight percent. The effect of relative humidity (RH) over a range of 30–90% on AC conductivity and capacitance has been investigated. Use of carbon fibers with graphene nanoplatelets significantly enhances the electrical conductivity and dielectric constant as compared to carbon-epoxy laminate without graphene nanoplatelets. The two parameters reveal linear dependence on humidity in the low frequency range of 100–1000 Hz. The AC conductivity increases at the rate of 2 nSm−1/% RH in laminate with carbon fiber and it increases to 50 nSm−1/%RH with the incorporation of graphene nanoplatelets. The increase in AC conductivity from 100 Hz to 1000 Hz is in the range of 0.1 to 0.2 μS/m with carbon fibers and it increases from 1 to 4 μS/m with the inclusion of graphenenanoplatelets. Increase is AC conductivity from 1 kHz to 10 MHz is by five orders of magnitude, with a steep increase around 5 MHz in both laminates. The incorporation of graphenenanoplatelets helps to increase the dielectric constant by 2.4–2.8 times as compared to epoxy with carbon fiber. The swelling in the laminates estimated after 96 h of exposure to 90% RH is observed to be less than 0.05%. The use of graphenenanoplatelets improves moisture sensitivity of the carbon-epoxy laminate.

Investigation of Thermal, Mechanical and Shape Memory Properties of 3D-Printed Functionally Graded Nanocomposite Materials.

In this study, a 3D-printed photocurable resin was developed by incorporating graphene nanoplatelets functionalised with melamine to investigate the thermal, mechanical, fracture and shape memory behaviours. The objective of this work was to produce a printed functionally graded nanocomposite material that has a smart temperature-responsive structure; presents good thermal stability, strength and fracture toughness; and can demonstrate shape-changing motions, such as sequential transformations, over time. The functionalised graphene nanoplatelets were examined via thermogravimetric analysis, Fourier transform infrared spectroscopy, Raman spectroscopy and ultraviolet-visible spectroscopy. Thermogravimetric analysis showed that the degradation temperature of the nanocomposite containing 0.1 wt% of functionalised graphene nanoplatelets at the weight loss of 5% was 304 °C, greater than that of the neat one by 29%. Dynamic mechanical analysis results showed property enhancements of the storage modulus and glass transition temperature. Fracture toughness, tensile strength and impact resistance were improved by 18%, 35% and 78%, respectively. The shape memory tests were performed to obtain the temperature-time recovery behaviour of the 3D-printed structures. The addition of functionalised graphene nanoplatelets demonstrated an enhancement in the shape recovery ratios. Generally, the five subsequent cycles were notably stable with a high recovery ratio of 97-100% for the flat shape and circular shape of the M-GNP specimens. On the other hand, these values were between 91% and 94% for the corresponding neat specimens.

Incorporation of graphene nanoplatelets with organic phase change materials – Studies on thermal conductivity enhancement, and thermal and chemical stability

Phase change materials (PCMs) have the capability to store energy in form of latent heat, along with exceptional chemical and thermal stability. However, their main limitation lies in their thermal conductivity, which hampers the rate at which energy can be stored and released. In the current work, we have chosen graphene nanoplatelets (GNP) as the thermal conductivity enhancer and organic PCM melting at 21, 30, 35, and 46 °C and a hydrated salt melting at 24 °C. Melt blending technique was used to develop GNP-enhanced PCM, and their chemical and thermal properties were studied. Thermal conductivity was studied in the temperature varying from 25 to 50 °C and we observed a substantial upsurge in thermal conductivity with an upsurge in concentration of GNP. Specific heat was found to increase with an upsurge in concentration of nanoparticles. DSC thermograms depicted a minor upsurge in melting and solidification temperatures and a decline in their latent heat concerning an upsurge in GNP concentration. Subcooling temperature of all pure and GNP-enhanced composites was found to be less than 10 °C. FTIR spectrum peaks designated the presence of physical interaction with the nonappearance of chemical interaction between GNP and PCM. TGA thermograms depicted a minor weight loss till 165 °C and rapid weight reduction in temperature range of 165 – 270 °C which conveys that incorporation of GNP has enhanced thermal stability of PCM. From thermophysical and chemical characterization of pure and GNP-enhanced PCM, we can conclude that GNP-enhanced composites can be used for enhanced heat transfer applications.

Studying the relationship between microstructure and properties of polylactic acid/styrene-ethylene butyl-styrene blend reinforced by graphene

The main purpose of this study was to investigate the relationship between microstructure and mechanical performance of polylactic acid when mixed with styrene-ethylene butylene-styrene copolymer and also graphene nanoplatelets. For this purpose, a series of neat polymer blends were first prepared with varying mixing ratios through a one-step melt mixing technique. Subsequently, the effect of various loadings of graphene nanoplatelets on the best mixing ratio (optimal composition) of the binary blend was investigated. To understand the different performances of various nanocomposites, the correlation of mechanical, rheological, and microstructural properties was thoroughly investigated using X-ray diffraction, scanning electron microscopy, linear viscoelastic behavior, tensile testing, and impact strength analyses. Furthermore, the influence of the mixing sequence of nanocomposites preparation on the microstructure and mechanical performance of nanocomposites was studied. Results demonstrated that the incorporation of graphene nanoplatelets as well as mixing sequence has a substantial effect on the final properties of prepared nanocomposites which was deeply discussed.

Effect of Incorporation of Graphene Nanoplatelets on Physicochemical, Thermal, Rheological, and Mechanical Properties of Biobased and Biodegradable Blends.

This work aimed to study the effect of the incorporation of graphene nanoplatelets (GRA 0.5% and 1% (w/w)) on the matrices of biobased polymers composed of starch-based materials (B20) and poly(butylene succinate) (PBS) using pine rosin (RES) as a compatibilizer. Three formulations were produced (B20/RES/PBS, B20/RES/PBS/GRA0.5%, and B20/RES/PBS/GRA1%), and their mechanical properties (tensile, flexural, hardness, and impact), rheological behavior, thermal properties (thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC)), chemical analysis (Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy), and contact angle were evaluated. Hardness (Shore D), tensile, and flexural moduli increased, whereas elongation at break and toughness decreased as GRA content increased. FTIR studies strongly supported the existence of interactions between polymeric matrices and the large surface area of GRA. The viscosity flow curves were well fitted to the Cross-Williams-Landel-Ferry (Cross-WLF) model, and the three formulations exhibited non-Newtonian (shear-thinning) behavior. The analysis of water contact angles indicated that the formulation surfaces have hydrophilic behavior. All the samples are thermally stable, and the results of this study can be used to optimize the application of biobased graphene-based composites for applications in injection molding industries.

Fresh and hardened performance of concrete enhanced with graphene nanoplatelets (GNPs)

This paper presents an investigation into the fresh and hardened properties of concrete enhanced with graphene nanoplatelets (GNPs). GNP dispersions were prepared using wet dispersion techniques and the influence of various factors on dispersion quality, such as mixing/dispersion methods, sonication time/intensity and GNP concentrations were evaluated. Sedimentation photos and zeta potential analysis were used to assesses the stability of GNP dispersions and determine optimal dispersion conditions for incorporation of GNPs into the concrete specimens. Further, advanced X-ray diffraction (XRD) techniques were used to determine the crystallographic structure of GNPs and a scanning electron microscope (SEM) revealed information about the external morphology (texture), composition and the orientation of the nano materials. Various GNP concentrations were explored including: 0.0, 0.05, 0.1, 0.15, 0.20, 0.25, 0.3 and 0.35 wt % and their effects on workability, apparent density, compressive strength and flexural strength were evaluated. The results suggested that the optimal concentration of GNP was 0.25 wt% which increased compressive and flexural strength of concrete by up to 20.7% and 8.8%, respectively. However, the addition of 0.25 wt% GNPs decreased workability by more than 50% compared to control specimens. Further, apparent density of concrete specimens was not affected by adding GNPs.

Design and industrial implementation of a multi-functional part produced by powder bed fusion

The use of robot end-effectors programmed to perform handling tasks in industrial environments has expanded in several sectors as a consequence of the rapid digital transformation seen in recent years. With such growing demands, additive manufacturing is evolving in the robotics field with more efficient, innovative, and customer-specific solutions owing to its design flexibility. Thus, this work presents a robot end-effector developed and produced by powder bed fusion (PBF) to execute palletizing operations in the automotive electronics industry, where electrostatic discharge interference is a critical concern. To guarantee the functionality of the developed robot end-effector under real conditions of implementation, prototypes of polyamide 12 (PA12) and PA12 incorporating graphene nanoplatelets were fabricated and characterized. This included the assessment of the mass, electrical surface resistance, and mechanical properties under tensile and compressive loads using biaxial strain gauges coupled to the prototypes for local strain monitoring. The experimental data were then used to define multilinear isotropic hardening models needed to numerically characterize the robotic system. At last, the final product was validated in an industrial environment at Bosch Car Multimedia S.A. Through the applied methodology, valuable insights in guiding process parameters optimization and materials selection for functional PBF parts depending on the technical requirements demanded by industrials are provided.

Development of Ultra-High-Performance Silica Fume-Based Mortar Incorporating Graphene Nanoplatelets for 3-Dimensional Concrete Printing Application

Although the use of 3D printing in civil engineering has grown in popularity, one of the primary challenges associated with it is the absence of steel bars inside the printed mortar. As a result, developing 3D printing mortar with ultra-high compressive, flexural, and tensile strengths is critical. In the present study, an ultra-high-performance mortar incorporating silica fume (SF) and graphene nanoplatelets (GNPs) was developed for 3D printing application. The concrete mixture added SF to the concrete mixture in the range between 0% and 20%, while GNPs were added as a partial replacement by cement weight from 0.5% to 2%. The flowability and the machinal properties of the proposed mortar, including compressive (CS), tensile (TS), and flexural strength (FS), were investigated and assessed. Microstructure analysis involving FESEM and EDX was also investigated and evaluated, while response surface methodology (RSM) was considered to predict and optimize the optimum value of GNPs and SF. Workability results show that the flowability is reduced when the amount of graphene increases. Based on the predicted and experimental results, ultra-high-strength mortar can be developed by including 1.5% of GNPs and 20% of SF, in which the CS jumped from 70.7 MPa to 133.3 MPa at the age of 28 days. The FS and TS were 20.66 MPa and 14.67 MPa compared to the control mix (9.75 MPa and 6.36 MPa), respectively. This favorable outcome was credited to the pozzolanic activity of SF and the effectiveness of GNPs in compacting the pores and bridging the cracks at the nanoscale level, which were verified by FE-SEM and EDX. In addition, the developed quadratic equations proved their accuracy in predicting and optimizing the mechanical properties with low error (less than 0.09) and high correlation (R2 > 0.97). It can be concluded that the current work is an important step forward in developing a 3D printing mortar. The lack of reinforcement in the printed mortar structure has been a considerable difficulty, and the SF and GNPs have increased the compressive, flexural, and tensile strengths of the mortar. Thus, these improvements will encourage the industry to utilize sustainable materials to produce more affordable housing.

Enhanced corrosion performance of ultrasonically shot peened and graphene nanoparticles reinforced squeeze-cast AZ91 magnesium alloy

The current study examined the influence of ultrasonic shot peening (USP) for 10, 20, and 30 s on the corrosion behavior of AZ91 alloy integrated with graphene nanoplatelets (GNPs) (0.5, 1.0, 2.0 wt%) by squeeze casting. The Volta potential associated with Mg17Al12 phase in the AZ91 alloy decreased with the incorporation of GNPs. All of the nanocomposites illustrate less weight loss and hydrogen evolution, which further decreases after USP. With GNPs’ addition to the AZ91 alloy, the open circuit potential increases positively and became much nobler after USP. All the nanocomposites display lesser corrosion rates contrasting to AZ91 alloy, decreasing further after USP. The 20 s ultrasonically shot-peened (USPed) AZ91–2.0GNPs demonstrates the best corrosion resistance. Mg(OH)2, MgCO3, and Al-rich compounds were the predominant corrosion products generated on the alloys and nanocomposites, with the least in the 20 s USPed AZ91–2.0GNPs nanocomposite. The smaller grains, lower Mg17Al12 phase content, and lower Volta potential betwixt the α-Mg and Mg17Al12 phases improve the cast nanocomposites’ resistance to corrosion. On the contrary, the compressive residual stress and finer grains at the surface of the USPed alloy and nanocomposites ameliorated the corrosion resistance significantly.

Stress and damage-sensing capabilities of asphalt mixtures incorporating graphene nanoplatelets

The development of innovative sensing technologies is essential for implementing smart road pavement monitoring systems. The design of asphalt-based materials with intrinsic self-sensing capabilities represents a promising solution in that regard. Despite this, this technology is still not mature and further efforts should be made for its development. With this aim, the present paper evaluates the self-sensing response of asphalt mixtures incorporating graphene nanoplatelets (GNPs), and proposes the use of a digital signal processing technique, based on wavelet transform, for the analysis of the electrical signals generated by the mixture. The results showed that the mixtures exhibited both stress and damage sensing functions, albeit some issues related to the dispersion of GNPs should be further investigated. In addition, wavelet transform analysis seems to be able to capture insightful information about the electrical response of the mixture, as well as its structural condition, useful for traffic and pavement health monitoring purposes.

Effect of graphene nanoplatelets on mode I fracture Toughness of epoxy adhesives under water aging conditions

ABSTRACT In this work, graphene nanoplatelets (GNP) are used to reinforce epoxy adhesives, and the effects of GNP on mode I fracture toughness of adhesive under water aging condition are studied through double cantilever beam (DCB) test. Although the GNP reinforced adhesives deliver slightly higher GIC than neat epoxy before water aging, they exhibit an exceptional 21.93% higher GIC after immersing in water for 56 d, at a GNP content of 0.25 w.t.%. According to the experimental results, the effectively dispersed GNP could significantly alleviate the degradation rate in mode I fracture toughness due to the water aging. For example, compared to the non-aging condition, the mode I fracture toughness of neat epoxy decreases by 29.19% after 56 d of water aging. In a stark contrast, the degradation rate for 0.25 w.t.% GNP reinforced adhesive is only 15.76%. In addition, it is observed that GNP greatly improves the fracture surface roughness of DCB samples, which suggests that the incorporation of GNP is able to delay the negative effect of water aging on mode I fracture toughness of adhesive by lowering the diffusion of water into the adhesive, while increasing torturous of the crack propagation path.

Improving the Dielectric, Thermal, and Electrical Properties of Poly (Methyl Methacrylate)/Hydroxyapatite Blends by Incorporating Graphene Nanoplatelets

Improving the Dielectric, Thermal, and Electrical Properties of Poly (Methyl Methacrylate)/Hydroxyapatite Blends by Incorporating Graphene Nanoplatelets