Graphene Nanoplatelets Research Articles

PIEZORESISTIVE SENSORS BASED ON PVDF-HFP REINFORCED WITH GNPs FOR HEALTH MONITORING APPLICATIONS

Wearable technology has become increasingly popular in recent years. Wearable sensors are systems made of flexible substrates which good adaptability to human motion monitoring. In parituclar, they allow doctors to obtain real-time data from patients by detecting small changes in baseline values over time, such as the movement of various joints or muscles, heart activity, breathing, and even sweat. In this regard, polymers can offer good flexibility, stretchability, and long-term reliability, which, together with the possibility of modifying their electrical response with conductive nanofillers, makes them promising for the fabrication of this kind of sensors, as their electrical conductivity changes with applied strain. In this work, piezoresistive sensors based on poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) reinforced with graphene nanoplatelets via solvent casting are presented. Here, both the electrical and electromechanical responses are evaluated as a function of different processing conditions, more specifically, sonication time and evaporation temperature. Then, several successful proof-of-concept tests have been carried out from human motion monitoting to pressure sensing applications, with very high sensitivities, being very promising for this kind of applications.

Microstructural, mechanical, thermo‐rheological, barrier, and antimicrobial properties of coextruded tri‐layer polylactide/encapsulated geraniol/polylactide‐graphene nanoplatelets films

AbstractA sustainable polylactide (PLA)‐based multilayer food packaging film was developed to improve neat PLA films' modest mechanical, thermal, and water/gas barrier properties. To improve the desired properties and impart antimicrobial aspects to the composite films, graphene nanoplatelets (GNP), and geraniol (GER) were reinforced into single‐layered PLA films. The project aimed to assemble three monolayers into multilayer films (MLF) through a coextrusion process, keeping the PLA‐GER layer in the core. X‐ray diffractograms, micrographs, and roughness parameters of the films demonstrated the dispersion of GNP in the film. Thermogravimetric analysis confirmed an enhancement in the thermal stability of the MLF by around 8°C when compared against single‐layer PLA films. An improvement in mechanical rigidity was supported by tensile (>87%) and rheological measurements. The polymers exhibit liquid‐like behavior in melts. Barrier properties did not improve for the MLF due to the agglomeration of GNP. The excellent antimicrobial properties of the MLFs for 3 weeks of storage at refrigerated conditions against both gram‐positive and gram‐negative pathogens were attributed to the release of GER from the film into the packed chicken samples and proved their potential for use in the food industry.

Surface engineering of textile structural composites with ZnO nanorods and graphene nanofillers for aircrew helmet applications

AbstractThis research aimed to augment the properties of interfibre interfaces through surface treatment with ZnO nanorods while simultaneously modifying the matrix with graphene nanoplatelets. The strategic approach of this research focused on synergizing these interventions to enhance the mesomechanical, and macromechanical properties, which are specifically targeted at improving the performance of aircrew helmets. This study investigated the effectiveness of these enhancements in improving the mechanical performance of aircrew helmets. The synergy of integrating ZnO nanorods and doped GNPs into Kevlar fabric resulted in a 29% increase in impact energy absorption compared to that of the standard Kevlar composite. Furthermore, the composite samples underwent thorough analysis through techniques such as thermogravimetric analysis (TGA), Raman spectroscopy, Fourier‐transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM) imaging. The findings indicate that incorporating 1% graphene nanofillers into Kevlar during the fourth seed cycle of ZnO treatment yields favorable mechanical performance characteristics. SEM at 50 KX magnification provided detailed visualization of the ZnO nanorods grafted onto the fabric substrates, with subsequent evaluation of the morphological damage and fractography of the impacted composites. The findings of this research hold significance for advancing the understanding of composite material behavior under impact loads and contribute to ongoing efforts to enhance the durability and performance of structural composites in diverse applications.Highlights Synergistic treatment with ZnO nanorods and graphene nanoplatelets boosted Kevlar composite properties for aircrew helmets. Adding 1% graphene during ZnO treatment increased impact energy absorption by 29%. Comprehensive analysis validated treatment efficacy, showing substantial mechanical improvements. The research advances composite understanding, paving the way for durable, high‐performance materials for applications like aircrew helmets.

Enhancing strength and ductility of graphene and ZrO2 nanoparticles hybrid reinforced AA2024 composite fabricate by laser powder bed fusion

The AA2024 aluminum alloy is difficult to manufacture by laser powder bed fusion (L-PBF) due to its crack sensitivity. This work introduces a novel crack-free graphene nano-platelets (GNPs) and ZrO2 nanoparticles hybrid-modified AA2024 alloy suitable for laser powder bed fusion (L-PBF). The columnar-to-equiaxed transformation caused by nanoparticles-inducing nucleation sites eliminates the cracks. A bimodal microstructure consists of coarse columnar grains and ultrafine equiaxed grains, which are formed in the as-built composites. Compared with the L-PBF prepared AA2024 alloy and 1 wt% ZrO2/AA2024 composite, the (0.2 wt% GNPs + 1 wt% ZrO2)/AA2024 composite exhibit the highest tensile strength of 382 MPa and elongation of 16 %. The introduction of GNPs and ZrO2 nanoparticles provide dual increment in both tensile strength and ductility compared with single ZrO2 nanoparticles modified AA2024. Following further T6 heat treatment, the tensile strength increased significantly to 624 MPa, but the elongation decreased dramatically to 5.6 %. In-depth analysis was provided of the strength and ductility improvements induced by GNPs/ZrO2 nanofiller in this investigation.

Enhancing polypropylene composites: synergistic effects of graphene nanoplatelets and glass fibers on mechanical and thermal properties

Enhancing polypropylene composites: synergistic effects of graphene nanoplatelets and glass fibers on mechanical and thermal properties

Advanced one pot photochemical surface modification approach towards graphene materials and their application in dye removal

Carbonaceous materials have shown undisputable promise as adsorbents and catalysts in various applications. The ability to tune key features such as specific surface area and functionality to improve the activity, represents a key advantage. However, this requires the development of general and versatile synthetic methods to deliver these multifunctional materials. This work reports a convenient general approach to prepare a series of graphene-chromophore systems. Two photochemical methods involving a step-by-step procedure and a one-pot method were compared. It was found that the two-step procedure is limited by the stability of the diazonium salts and thus has a limited application. The one-pot method allows preparation of a wide range of different composites in an easy and inexpensive manner. Synthesised samples were characterised by a range of methods including electron microscopy, X-ray diffraction, infra-red spectroscopy and gas adsorption. Transmission electron microscopy analysis revealed an ordered array of chromophores on the surface of the graphene nanoplatelets. The samples were tested as potential materials for dye removal; these studies revealed that most graphene-chromophore materials can successfully remove organic pollutants such as methylene blue, rhodamine B and methyl orange from aqueous media.

Electrochemical sensor determines antibiotic residues of Chloramphenicol in fresh milk using modified Glassy carbon electrode based on nZVI/GNPs/TCPP nanocomposite material synthesized by green chemistry method

Chloramphenicol (CAP) is a broad-spectrum antibiotic widely used in medicine and agriculture since 1948 [1]. Currently, CAP is banned due to its potential health hazards [2]. Therefore, detecting antibiotic residual levels of CAP in food is necessary. The electrochemical method, characterized by its simplicity, speed, high sensitivity, ease of on-site analysis, and low cost, demonstrates potential in assessing antibiotic residual CAP compared to traditional methods such as liquid chromatography-mass spectrometry (LC-MS), liquid chromatography-electrochemical ionization-mass spectrometry (LC-EIS-MS/MS), gas chromatography-mass spectrometry (GC-MS),...[3]. In this study, a material from zero-valent iron nanoparticles combined with graphene nanoplatelets and porphyrin nanofibers (nZVI/GNPs/TCPP) synthesized through green chemistry methods was used as the electrode material to analyze antibiotic residual CAP in fresh milk samples using cyclic voltammetry (CV) and differential pulse voltammetry (DPV), promising results with a limit of detection (LOD) of 0,1212 μM, limit of quantification (LOQ) of 0,4040 μM, and sensitivity of 0,009998 μA.μM-1.cm-2.

A study of EMI shielding efficiency, dielectric, and impedance properties of polymer nanocomposites reinforced with Graphene nanoplatelets, montmorillonite, and copper oxide nanoparticles

ABSTRACT In the present study, polyvinylchloride (PVC) and polymethyl methacrylate (PMMA) blended nanocomposites comprised of graphene nanoplatelets (GNPs), montmorillonite (MMT), and copper oxide (CuO) nanoparticles were prepared through solvent casting approach. The structural and morphological measurements confirmed the presence and dispersion of nanofillers in the polymeric chains. Thermo-gravimetric analysis (TGA) and differential-scanning calorimetry (DSC) investigations suggested the improved thermal stability for nanocomposite with 1.5 wt% GNPs loading having minimum weight loss and reduction in Tm due to the presence of GNPs, MMT, and CuO acting as a barrier to oxygen molecule diffusion and polymer-chain movement in the nanocomposite. The dielectric and impedance properties of PVC/PMMA/MMT/GNP/CuO nanocomposite investigated in 1 Hz to 20 MHz frequency range and at room temperature have shown improved dielectric constant upto 90.59 in 1 Hz frequency. The σac measures to be improved by 0.0034 (S/m) after adding GNPs, MMT, and CuO resulted from the interfacial polarization effect. The cole–cole plot investigations have shown the formation of semicircles for higher nanofiller loadings of nanocomposite. A drastic improvement in the SETotal was observed from lower to higher nanofiller concentrations. The total SE obtained for the nanocomposite with 2.5 wt% GNPs is upto 5 dB in 8–12 GHz range with absorption dominant nature of nanocomposite.

Boosted wear and electrochemical corrosion resistance properties of Ti6Al4V alloy via graphene nanoplatelets and titanium particles

The Ti6Al4V(TC4) alloy is renowned for its robust strength, low density, exceptional resistance to corrosion, and outstanding biocompatibility, making it applicable in aviation, biomedical, and various other industries. However, its application is hindered by its inherent limited hardness and suboptimal resistance to wear. TiC, known for its compatibility with titanium alloys, serves as a frequently employed reinforcing phase in titanium matrix composites. The incorporation of TiC reinforcing phases can be classified into two categories: “in-situ” and “ex-situ”. In this research, graphene nanoplatelets (GNPs) and pure titanium (TA2) were ball-milled to produce graphene‑titanium particles, which were then utilized for the in-situ generation of TiC, and compared with the direct incorporation of nano-TiC into the titanium matrix. The deposition samples of GNPs/TA2/TC4 and nano-TiC/TA2/TC4 composites were fabricated employing the laser directed energy deposition technique. The findings of this research suggest that during the manufacturing process, the graphene nanoplatelets underwent dissolution within the molten pool. The carbon elements from the dissolved graphene nanoplatelets reacted in-situ with titanium elements, resulting in an ‘in-situ reaction’ that generated the TiC reinforcement phase. The microstructures of GNPs/TA2/TC4 and nano-TiC/TA2/TC4 deposition samples exhibit primary TiC in granular, floral, and dendritic morphologies. However, the TiC dendrites generated in situ by GNPs show shorter crystal axes. The GNPs/TA2/TC4 deposition sample displays the most pronounced grain refinement, featuring a mean grain size measuring 2.27 μm. The microhardness values of GNPs/TA2/TC4 and nano-TiC/TA2/TC4 deposition samples are (413 HV0.2 and 526 HV0.2), respectively, representing an increase of approximately 33 % and 69 % compared to the TA2/TC4 pure material deposition sample. The GNPs/TA2/TC4 deposition sample exhibits the lowest friction coefficient (0.236), indicating superior wear resistance. Moreover, the corrosion resistance of the GNPs/TA2/TC4 deposited sample is optimal (RP = 23,536 Ω cm2, Icorr = 2.03 × 10−6 A·cm−2, Ecorr = −0.703 V/SCE).

Effects of warm-mix additives, anti stripping agent, and graphene nanoplatelet on the cracking resistance, moisture susceptibility, and cost effectiveness of stone mastic asphalt

Moisture and cracking damages are two of the most common asphalt pavement distresses in the United States. The use of stone matrix asphalt mixture has gained popularity due to its high durability, resistance to permanent deformation and cracking, and reduced noise pollution. Warm-mix additives and nanomaterials have also gained significant interest as promising asphalt binder additives. In order to achieve enhanced resistance to moisture and cracking in extremely wet regions, this study investigated the effects of three warm-mix additives, an anti-stripping agent, and one nanomaterial (graphene nanoplatelet) on the cracking and moisture resistance performance of stone matrix asphalt. Fourier transform infrared spectroscopy and sessile drop tests were used to evaluate the functional groups and moisture susceptibility of the modified asphalt binder blends, respectively. The indirect tensile asphalt cracking test and the modified Lottman tests were used to evaluate the mixtures' resistance to cracking and stripping damage. A cost-effectiveness analysis as well as a two-dimensional performance interaction diagram were employed based on the laboratory performance of the mixtures. Results indicated that the graphene nanoplatelet modification of the asphalt binder had the highest wettability potential, adhesion, and debonding properties, as well as moisture resistance potential compared to other additives. In terms of mixture cracking performance, both the graphene nanoplatelet and a chemical warm-mix asphalt significantly improved the mix cracking performance by 34.1 and 30.0 %, respectively, compared to the control mix. However, the graphene nanoplatelet modification had a tensile strength ratio of 0.76, which is below the acceptance threshold of 0.80 set by AASHTO T 283 for moisture damage resistance of asphalt mixture. Overall, all mixtures with warm-mix additives showed adequate cracking and stripping damage resistance performance and are expected to be cost-effective.

Hexagonal boron nitride nanosheets/graphene nanoplatelets/cellulose nanofibers-based multifunctional thermal interface materials enabling electromagnetic interference shielding and electrical insulation

Thermal interface materials (TIMs) that block electromagnetic interference (EMI) and current leakage are essential for high-density, high-power devices and compact form factors of electronic and mobility platforms. However, their coupled thermal-electrical-electromagnetic characteristics involve mismatches in thermal conductivity, electrical insulation, and EMI shielding, limiting the multifunctionality. Herein, a sandwich-like structural design that rationally combines graphene nanoplatelets (GNPs), hexagonal boron nitride nanosheets (BNNSs) and cellulose nanofibers (CNFs) is presented toward multifunctional trilayer TIMs enabling high thermal conductivity, EMI shielding, electrical insulation, mechanical compatibility and flame retardancy. The top and bottom BNNSs serve as electrically insulating yet thermally conductive layers while the GNPs in the central layer mitigate EMI and the CNFs as a binder complete the mechanical properties for the lamella-like trilayers. The resulting TIM exhibits a high in-plane thermal conductivity (25.5 W/m·K), and the LED cooling system using the TIM demonstrates the capability of reducing the operating temperature. Furthermore, it shows a high-volume resistivity (4.12 × 1013 Ω cm) and EMI shielding effectiveness (29.0 dB) at X-band frequencies. Its mechanical robustness is confirmed with tensile strength and elongation of 65.0 MPa and 2.36 %, and the high flame retardancy is validated. The outcomes will inspire tailoring multifunctional TIMs using lamellar structures that optimally combine micro/nanomaterials.

Micromechanical modeling of thermal conductivities of unidirectional carbon fiber/epoxy composites containing carbon nanotube/graphene hybrids

This article deals with the micromechanical modeling of thermal conductivities of the unidirectional carbon fiber (CF)-reinforced composites with carbon nanotube (CNT)/graphene nanoplatelet (GNP)-enriched epoxy matrix. The thermal conductivity of epoxy-based nanocompounds enriched through the incorporation of CNT/GNP hybrids is estimated within the framework of micromechanics. The significant contribution of several microstructures, including the volume fraction, dimension, and straightness of nanofillers, thermal resistance at the interface of the nanofillers and epoxy matrix, and the percolation effect on the nanocomposite thermal conductivity is considered. Furthermore, the method of cells (MOC) is used to anticipate the axial and transverse thermal conductances of unidirectional composites featuring CFs integrated into the CNT/GNP-enriched polymer nanocomposite matrix. The results reveal that incorporating a combination of GNTs and CNTs into the polymer matrix significantly increases the transverse thermal conduction of the multiphase compound. Several factors contribute to improved thermal conductance of the transverse direction in CF/CNT/GNP composites: (i) higher nanofiller concentration, (ii) presence of straight nanofillers, and (iii) use of larger nanofillers. The predictions of micromechanical modeling give good agreement with available experiments. This study compares the transverse and axial thermal conductivity of unidirectional compounds predicted by MOC method with results obtained using the finite element method.

Aluminum/Graphene Thermal Interface Materials with Positive Temperature Dependence.

Graphene is widely used in excellent thermal interface materials (TIMs), thanks to its remarkably high in-plane thermal conductivity (k∥). However, the poor through-plane thermal conductivity (k⊥) limits its further application. Here, we developed a simple in situ growth method to prepare graphene-based thermal interface composites with positively temperature-dependent thermal conductivity, which loaded aluminum (Al) nanoparticles onto graphene nanoplatelets (GNPs). To evaluate the variations in thermal performance, we determined the thermal diffusivity and specific heat capacity of the composites using a laser-flash analyzer and a differential scanning calorimeter, respectively. The Al nanoparticles act as bridges between the nanoplatelets, enhancing the k⊥ of the 1.3-Al/GNPs composite to 11.70 W·m-1·K-1 at 25 °C. Even more remarkably, those nanoparticles led to a unique increase in k⊥ with temperature, reaching 20.93 W·m-1·K-1 at 100 °C. Additionally, we conducted an in-depth investigation of the thermal conductivity mechanism of the Al/GNPs composites. The exceptional heat transport property enabled the composites to exhibit a superior heat dissipation performance in simulated practical applications. This work provides valuable insights into utilizing graphene in composites with Al nanoparticles, which have special thermal conductivity properties, and offers a promising pathway to enhance the k⊥ of graphene-based TIMs.

Enhanced EM shielding: Synergetic effect of zirconium ferrite, MWCNT, and graphene in LDPE polymer composite to counteract electromagnetic radiation in the X-band range

In this work, we present a study on the evaluation of electromagnetic (EM) shielding performance using low-density polyethylene (LDPE) polymer composite as an EM wave-absorbing material in the X-band range. Using magnetic and conducting fillers is proven to enhance the shielding performance of the composite polymer. In this study, we show that the use of zirconium ferrite (ZrFe2O4) as magnetic filler and multiwall carbon nanotube (MWCNT)/ graphene nanoplatelet (GNP) as conductive fillers exhibit excellent electromagnetic wave-absorbing properties in the X-band range. Fillers and the polymer matrix are characterized by various techniques such as XRD, SEM, color mapping, EDAX, etc. Systematic optimization of the composition of LDPE polymer composite with varying ZrFe2O4 and conducting fillers are carried. The results showed that a composite with 5 wt% displayed enhanced EMI shielding in X-band (8.2–12.4 GHz) within the concentrations studied. For the optimized composite highest shielding effectiveness being 58.57 dB (99.9936 %) at 10.3 GHz is recorded. The shielding mechanism and dominate shielding phenomena are evaluated by calculating coefficients of absorption, reflection and transmittance. The findings of this study show that the use of ZrFe2O4 has excellent potential as a magnetic filler in polymer-based composites for EMI shielding applications.

Improved magnetic, electrical, and dielectric characteristics of graphene nano-platelets (GNPs)-Integrated Ni0·4Cd0·6Fe1.97Sm0.03O4 ferrite composites synthesized via sol-gel auto-combustion method

This research work analyzes the impact of graphene nanoplatelets (GNPs) on the structural, electrical, dielectric, optical, and magnetic properties of the Ni0·4Cd0·6Fe1.97Sm0.03O4/x-GNPs (SNCF/GNPs) composites (x = 0 %, 2.5 %, and 5 %) prepared via the sol-gel auto-combustion route. The results revealed that SNCF particles were distributed on GNPs which improved the multifaceted properties of SNCF spinel ferrites. XRD analysis confirmed the FCC spinel structure with a minimum crystallite size (D) of 18.99 nm for sample with 5 wt %GNPs. The DC electrical resistivity decreased from 9.06 × 1011 Ω-cm at 313K to 1.41 × 108 Ω-cm at 673K, revealing the semi-conducting nature of composites. The improved electroconductivity and reduced bandgap energy are observed for samples with minimum resistivity 1.02 × 105 Ω-cm at 673K and 1.70 eV energy, respectively, containing 5 wt %GNPs. Samples show higher permittivity values at low frequency and decreased at high frequency. The maximum ac conductivity is observed for composite with 5 wt %GNPs which is attributed to the hopping mechanism. Finally, the magnetization (Ms) increased from 52.24 to 79.71 emu/g with increasing GNPs contents. Hence, the synthesized composites with 5 wt %GNPs are more favorable than the pure sample for application in waste-water treatment, high-frequency devices, and energy storage devices.

3 Body abrasion test of HVOF sprayed WC-10Co-4Cr and WC-10Co-4Cr + 2 % graphene coating on IS-2062 steel

This study investigates the microstructural characteristics, mechanical properties, and slurry abrasion resistance of WC-10Co-4Cr and WC-10Co-4Cr + GNPs coatings deposited using the High-Velocity Oxy-Fuel (HVOF) process. Cross-sectional micrographs, EDS line scans, and spectra reveal uniform distribution and proper adhesion of tungsten carbide particles, cobalt, chromium, and graphene nanoplatelets (GNPs) throughout the WC-10Co-4Cr + GNPs coating. Microstructural analysis indicates denser structure and reduced porosity in the WC-10Co-4Cr + GNPs coating, leading to enhanced abrasion resistance. Mechanical testing demonstrates higher microhardness and bond strength in the WC-10Co-4Cr + GNPs coating, attributed to the incorporation of GNPs and Laser Surface Texturing (LST). Slurry abrasion tests show substantial reductions in mass loss for both coatings compared to the pristine substrate, with the WC-10Co-4Cr + GNPs coating exhibiting superior performance due to its densification and lubrication effect of GNPs. Overall, the WC-10Co-4Cr + GNPs coating presents a promising solution for applications requiring high wear resistance and durability in harsh environments.

Indirect prediction of graphene nanoplatelets-reinforced cementitious composites compressive strength by using machine learning approaches

Graphene nanoplatelets (GrNs) emerge as promising conductive fillers to significantly enhance the electrical conductivity and strength of cementitious composites, contributing to the development of highly efficient composites and the advancement of non-destructive structural health monitoring techniques. However, the complexities involved in these nanoscale cementitious composites are markedly intricate. Conventional regression models encounter limitations in fully understanding these intricate compositions. Thus, the current study employed four machine learning (ML) methods such as decision tree (DT), categorical boosting machine (CatBoost), adaptive neuro-fuzzy inference system (ANFIS), and light gradient boosting machine (LightGBM) to establish strong prediction models for compressive strength (CS) of graphene nanoplatelets-based materials. An extensive dataset containing 172 data points was gathered from published literature for model development. The majority portion (70%) of the database was utilized for training the model while 30% was used for validating the model efficacy on unseen data. Different metrics were employed to assess the performance of the established ML models. In addition, SHapley Additve explanation (SHAP) for model interpretability. The DT, CatBoost, LightGBM, and ANFIS models exhibited excellent prediction efficacy with R-values of 0.8708, 0.9999, 0.9043, and 0.8662, respectively. While all the suggested models demonstrated acceptable accuracy in predicting compressive strength, the CatBoost model exhibited exceptional prediction efficiency. Furthermore, the SHAP analysis provided that the thickness of GrN plays a pivotal role in GrNCC, significantly influencing CS and consequently exhibiting the highest SHAP value of + 9.39. The diameter of GrN, curing age, and w/c ratio are also prominent features in estimating the strength of graphene nanoplatelets-based cementitious materials. This research underscores the efficacy of ML methods in accurately forecasting the characteristics of concrete reinforced with graphene nanoplatelets, providing a swift and economical substitute for laborious experimental procedures. It is suggested that to improve the generalization of the study, more inputs with increased datasets should be considered in future studies.

Composites of Titanium-Molybdenum Mixed Oxides and Non-Traditional Carbon Materials: Innovative Supports for Platinum Electrocatalysts for Polymer Electrolyte Membrane Fuel Cells.

TiO2-based mixed oxide-carbon composite support for Pt electrocatalysts provides higher stability and CO tolerance under the working conditions of polymer electrolyte membrane fuel cells compared to traditional carbon supports. Non-traditional carbon materials like graphene nanoplatelets and graphite oxide used as the carbonaceous component of the composite can contribute to its affordability and/or functionality. Ti(1-x)MoxO2-C composites involving these carbon materials were prepared through a sol-gel route; the effect of the extension of the procedure through a solvothermal treatment step was assessed. Both supports and supported Pt catalysts were characterized by physicochemical methods. Electrochemical behavior of the catalysts in terms of stability, activity, and CO tolerance was studied. Solvothermal treatment decreased the fracture of graphite oxide plates and enhanced the formation of a reduced graphene oxide-like structure, resulting in an electrically more conductive and more stable catalyst. In parallel, solvothermal treatment enhanced the growth of mixed oxide crystallites, decreasing the chance of formation of Pt-oxide-carbon triple junctions, resulting in somewhat less CO tolerance. The electrocatalyst containing graphene nanoplatelets, along with good stability, has the highest activity in oxygen reduction reaction compared to the other composite-supported catalysts.

Effect of synergistic action of anodising and graphene on the mechanical properties of fibre-reinforced metal laminates

Fibre reinforced metal laminates (FMLs) are widely used in various fields due to their excellent properties. However, the weak interlayer properties of FMLs limit their applications. In this paper, the interlayer properties of FMLs are enhanced by anodising the 2024-T3 aluminium alloy layer in FMLs or by epoxy matrix modification of graphene nanoplatelets (GNPs). The effect of both synergistic impacts on the interlayer properties of most FMLs is investigated. The FMLs were manufactured using the wet lay-up technique using 2024-T3 aluminium alloy, E51 epoxy and EW100 glass fibre. The results showed that the type I fracture toughness, tensile strength, flexural strength, interlayer shear strength and single layer shear strength of FMLs after anodic oxidation treatment were increased by 406.4%, 10.3%, 18.3%, 42.6% and 28.3%, respectively, compared with those of pure FMLs. The type I fracture toughness, tensile strength, flexural strength, interlayer shear strength and single layer shear strength of the GNPs-modified FMLs matrix were increased by 280.4%, 3.7%, 6.8%, 34.5% and 19.1%, respectively, compared with those of pure FMLs. Moreover, the synergistic effect of FMLs indicates that the simultaneous anodic oxidation and GNPs modification of FMLs can lead to the best mechanical properties of FMLs. Microscopic images and schematics illustrate the toughening mechanism of anodising and GNPs, including the enhancement of aluminium/resin interface and fibre/resin interface and the enhancement of resin matrix properties.

Nanoplatelet Orientation and Young’s Modulus of Graphene/Phenoxy Nanocomposites

AbstractWe report on the development of phenoxy-graphene nano-composite fibres for improving the toughness of thermoset composites. In this paper, a systematic experimental investigation into the underlying mechanisms of graphene nanoplatelets (GNP) reinforcement of phenoxy nanocomposite fibres prepared via melt spinning is provided. The analysis reveals a tangential orientation of GNP in the outer layer of the fibres, while such orientation is absent in the fibre core region. We show that the relative size of the fibre sheath depends on process variables and exhibits a linear relationship with the modulus of GNP obtained via theoretical analysis using simple rule of mixtures. This is because the area ratio (AR) is proportional to the orientation degree of GNP. This indicates that the enhancement of the Young’s modulus of fibres mainly originates from the increased AR of the fibre sheath layer where the orientation of GNP is more regular.