Graphene Nanoplatelets Nanocomposites Research Articles

CuFe2O4/GNPs nanocomposites for symmetric supercapacitors and photocatalytic applications

The design of novel and highly efficient multifunctional nanocomposite materials has attracted great attention due to the materials’ applications in supercapacitors and wastewater treatment. In this work, CuFe2O4 (CuF) nanoparticle and graphene nanoplatelet nanocomposites ((CuF)1−x (GNPs) x ) have been fabricated by an in situ coprecipitation technique. The prepared (CuF)1−x (GNPs) x nanocomposites exhibit high energy storage (264.0 F g−1) with appreciable cyclic durability (74% over 1000 cycles), in a symmetric two-electrode supercapacitor cell, which can be attributed to the GNPs’ induced conductivity enhancement, reduced agglomeration of CuF nanoparticles, interfacial transfer of charge and Fe–O–C and Cu–O–C covalent bonds in the nanocomposites. These factors also play a central role in increasing the photocatalytic efficiency. The nanocomposites show excellent visible light-mediated photodegradation efficiency (99.1% in 160 min) for methylene blue in water solution. The results suggest that the synthesized nanocomposites could be potential materials for the storage of electrochemical energy and photocatalytic decontamination of wastewater.

Effect of ball milling on the mechanical properties and crystallization of graphene nanoplatelets reinforced short chain branched‐polyethylene

AbstractShort‐chain‐branched‐polyethylene (SCB‐PE) is extensively used in domestic hot and cold piping systems. SCB‐PE nanocomposites using graphene nanoplatelets (GNPs) as a filler, were prepared in this work. The effect of ball‐milling as a premixing technique prior to melt‐mixing, on the crystallization and the nanomechanical properties of the composites has been studied. Two sets of SCB‐PE/GNPs nanocomposites with various filler loadings were prepared; one with and one without the ball‐milling step. The dispersion of the filler was evaluated by optical microscopy while the crystallization process was studied using differential scanning calorimetry. The nonisothermal crystallization's experimental data were analyzed using various methods. The materials' nanomechanical behavior was investigated by conducting nanoindentation tests. A finite element analysis process was developed to extract the composites' stress–strain behavior. The composites prepared with ball‐milling presented improved dispersion of GNPs in the SCB‐PE matrix, which affected the crystallization, while nanoindentation tests showed significantly enhanced mechanical properties.

Nanomechanical evaluation of poly (vinylidene fluoride) nanocomposites reinforced with hybrid graphene nanoplatelets and titanium dioxide

This study further enhanced nanomechanical properties of poly (vinylidene fluoride) (PVDF) using hybrid graphene nanoplatelets (GNPs) and titanium dioxide (TiO2) nanopowder. The hybrid nanocomposites were prepared via solution blending and melt-mixing techniques. GNPs and TiO2 nanopowder were surface modified to promote compatibility with the PVDF matrix. Scanning electron microscope (SEM) revealed high degree of dispersion of the nanoparticles in the polymer matrix. The nanomechanical properties were examined using Anton Paar Instrumented Nanoindenter. By incorporation of GNPs-TiO2 hybrid nanoparticles in the matrix, there were increase in nanomechanical behaviors such as hardness, elastic modulus, stiffness and resistance to plastic deformation. For instance, hardness of 3.34wt%GNPs-10wt%TiO2 (115.2 MPa) increased by 79.7% and 17.2% compared to PVDF (64.1 MPa) and 3.34wt%GNPs (98.3 MPa) nanocomposite, respectively. The enhanced properties of the hybrid nanocomposites were due to network strengthening and hardening and restriction of polymer chains mobility offered by rough surfaces of GNPs-TiO2 hybrid nanoparticles.

Electrical Conductivity and Antenna Properties of Polyaniline filled GNPs Nanocomposites

This study was conducted to investigate the potential of utilizing conductive polymer nanocomposite for flexible type antenna application. The polyaniline (PANI) filled with graphene nanoplatelets (GNPs) nanocomposites were synthesized by an oxidative aniline polymerization in an acidic medium. The PANI/GNPs nanocomposites were then characterized by using various spectroscopy and imaging tools. It was found that the strong interaction between PANI macromolecules and GNPs flakes is caused by the strong ?-? conjugation between them, as validated by an increase of Id/Ig ratio of PANI/GNPs nanocomposites. As a result, it established a three-fold improvement for the electrical conductivity of PANI/GNPs nanocomposites, due to the larger amount of charge carrier transport at higher GNPs nanofiller loadings (1.00 wt.%). Later, the PANI/GNPs nanocomposites powder was applied to the cotton fabric by integrating it with a rubber paint slurry. Electrical conductivity, antenna gain, return loss, and radiation pattern of the antenna were reported. It was found that PANI/GNPs flexible textile antenna possessed a constant gain of 4.1809 dB, return loss at -13.154 dB, and radiation pattern which operated at 10.36 GHz for 100% improvement of electrical conductivity, in comparison with unfilled PANI. From these findings, it can be said that the development of wearable textile antenna utilizing PANI/GNPs nanocomposites on the cotton fabric as flexible radiation patch, has great potential for wireless communication purposes.

Tailoring the rheology and electrical properties of polyamide 66 nanocomposites with hybrid filler approach: graphene and carbon nanotubes

AbstractThe aim was to improve the processability and reduce the melt viscosity of well‐known nanocomposites based on polyamide 66 (PA66) and carbon nanotubes (CNT), while keeping the good electrical conductivity gained after the addition of CNT. Thus, a nanocomposite based on PA66 as the thermoplastic matrix and 3% of CNT was selected. At this composition, a percolated network is created and the material is electrically conductive. The approach followed was the addition of graphene nanoplatelets (GNP) of two different lateral sizes to obtain a PA66 nanocomposite with hybrid filler: CNT/GNP. In addition, a third nanocomposite of PA66 with GNP only was prepared for comparison purposes. The rheological characterization determined that adding 1% of GNP of 2 μm particle size decreased the viscosity of the system by 87%. However, the electrical conductivity was diminished to some extent, from 10−5to 10−9 S cm−1approximately. The Cross rheology model described successfully the experimental rheological data. The CNT/GNP nanocomposite exhibited faster relaxations, almost four orders of magnitude, in comparison with the CNT nanocomposite but slower than the GNP nanocomposite. The nanoparticles improved the crystallization ability of PA66 acting as nucleating agents and increasing the PA66 crystallization temperature by almost 10 °C. Self‐nucleation experiments demonstrated a supernucleation feature of the hybrid filler. The nucleation efficiency was about 500%. © 2021 Society of Chemical Industry

Reinforced AZ91D magnesium alloy with thixomolding process facilitated dispersion of graphene nanoplatelets and enhanced interfacial interactions

Magnesium matrix nanocomposites reinforced with graphene nanoplatelets (GNPs) additives have long been considered as exciting prospects among nanotechnology applications. Here, the thixomolding process, an extremely efficient dispersing technology, was applied to prepare AZ91D magnesium alloy- GNPs nanocomposites with different GNPs contents (0, 0.1, 0.3, 0.6, 0.9 and 1.2 wt%). The effects of screw rotate rate ( R S ) and injection velocity ( V I ) on microstructures, GNPs dispersibility and mechanical properties were investigated. The GNPs, fairly uniform dispersion in the nanocomposites, were incorporated in the α-Mg grains, not only in the grain boundaries. Strong bonding interfaces between GNPs and alloy matrix were established because of the formed MgO nanoparticles leading to the formation of Mg/MgO semi-coherency interface and MgO/GNPs interface. Compared with other previously reported results, a relatively higher overall efficiency was achieved in the prepared magnesium matrix nanocomposites. The developed technology has a potential for large-scale industrial production of not only thin-walled complex parts, but also thick-walled products such as automobile parts with complex structure.

On the machining analysis of graphene nanoplatelets reinforced Ti6Al4V matrix nanocomposites

Abstract Negligible work has been reported on exploring the machinability aspects of titanium-based nanocomposites. High-density graphene nanoplatelets (GNPs) reinforced Ti6Al4V matrix nanocomposites are developed by using a high-frequency induction heating technique. The nanocomposites are developed with different percentages of GNPs, including 0 wt.% (base-Ti6Al4V), 0.3 wt.%, 0.6 wt.%, and 1.2 wt.% (GNPs/Ti6Al4V). Afterward, the machining behavior of the Ti6Al4V nanocomposites is investigated in detail during milling in terms of the cutting force components, surface roughness, surface morphology, microhardness and chips morphology. The milling results show that the addition of GNPs reinforcements considerably affects the machining performance of the nanocomposites. Even with high hardness, the 0.3 wt.% and 1.2 wt.% GNPs/Ti6Al4V nanocomposites showed lower cutting forces than the base-Ti6Al4V, i.e., leading to energy conservation. This is mainly due to the profound effect of the GNPs on the hardness, microstructure, and developed phases (TiC and graphene agglomeration) in the nanocomposites. Despite having a higher hardness, all the GNPs/Ti6Al4V nanocomposites revealed improved surface morphology as compared to the base-Ti6Al4V samples. For instance, at a high feed rate of 210 mm/min, the nanocomposites with 0.3 wt.%, 0.6 wt.%, and 1.2 wt.% GNPs contents exhibited approximately 39%, 13%, and 24%, respectively, lower roughness as compared to the base-Ti6Al4V. The 1.2 wt.% GNPs/Ti6Al4V samples show the lowest increase (3.2%) in the surface hardness even after machining at a higher cutting speed of 75 m/min. In comparison, the base-Ti6Al4V samples, which have lower (8.6%) initial hardness, exhibit an increase of 12.7% in surface hardness after machining at the same cutting speed (75 m/min). Overall, the 0.3 wt.% and 1.2 wt.% GNPs nanocomposites are close contestants for yielding the lower cutting forces, improved surface roughness, lower variation in the machined surface hardness, and smoother surface quality with minimum defects in most of the milling conditions, i.e., leading to sustainable machining and clean environment.

Poly(butylene succinate) and graphene nanoplatelet–based sustainable functional nanocomposite materials: structure-properties relationship

Sustainable functional polymer nanocomposites from renewable resources are extremely promising materials that can provide the next-generation of lightweight, multifunctional materials for several applications including energy storage, automotive, construction, defense, aerospace, consumer products, biomedical and functional coatings to name few. There is limited information on the use of sustainable polymers and graphene nanoplatelets (GNs), as well as the combinations of these two can provide reduced water permeability or enhanced electrical conductivity and improved thermal properties, and so on. Building upon this hypothesis, biobased poly(butylene succinate)/few-layer GN nanocomposites were prepared via a solventless melt-blending technique. Different characterization techniques such as differential scanning calorimetery, thermogravimetric analysis, dynamic mechanical analysis, dielectric spectroscopy, X-ray diffraction (XRD) and hot stage optical microscopy were used to study the thermal and structural characteristics. The melt blending was characterized by torque and temperature curves which showed that torque was reduced by up to 15 Nm, and melt temperature was improved by up to 5 °C. The improved crystallization of the composites in low concentrations of GN was observed. Graphene has been found to increase the crystallization temperature up to 10 °C and yielded pronounced spherulite structure, whereas peak shift was observed in XRD. High filler loading from 0.5 to 6.0 wt% was used to obtain more insights for few-layer graphene applications for thermoplastic polymer processing applications.

Multifunctional MgFe2O4/GNPs nanocomposite: Graphene-promoted visible light driven photocatalytic activity and electrochemical performance of MgFe2O4 nanoparticles

Herein, the electrochemical and photodegradation properties of magnesium ferrite and graphene-nanoplatelets nanocomposites, (MFO)1-x(GNPs)x, (x = 0.25, 0.50, 0.75) are reported. Benefitting from the effective interfacial interaction of the bi-phase nanocomposite and superior electrical conduction of GNPs, a significant enhancement in supercapacitive performance has been demonstrated. Interestingly, the electrochemical properties of nanocomposite electrode were found to depend on the loading ratio of GNPs. Notably the (MFO)0.50(GNPs)0.50 (50 wt % GNPs) shows an outstanding energy storage capacity i.e., 612 Fg–1 at 0.5 Ag–1 with 21.25 Wh kg−1 energy density at power density of 125 W kg−1 and retains ~76.8 % of the first cycle capacitance after continuous 1500 charge/discharge cycles. Furthermore, the (MFO)0.75(GNPs)0.25 (25 wt % GNPs) composite demonstrates admirable photodegradation efficiency (99.3 % in 60 min of visible light illumination) which is 3.2 times than that of neat MFO nanoparticles. The superior electrochemical and photodegradation performance suggests that the prepared nanocomposites can be effectively utilized in high‐performance energy storage devices and low cost, eco-friendly water purification systems.

Multifunctional Biocomposites Based on Polyhydroxyalkanoate and Graphene/Carbon Nanofiber Hybrids for Electrical and Thermal Applications

Most polymers are long-lasting and produced from monomers derived from fossil fuel sources. Bio-based and/or biodegradable plastics have been proposed as a sustainable alternative. Amongst those available, polyhydroxyalkanoate (PHA) shows great potential across a large variety of applications but is currently limited to packaging, cosmetics and tissue engineering due to its relatively poor physical properties. An expansion of its uses can be accomplished by developing nanocomposites where PHAs are used as the polymer matrix. Herein, a PHA biopolyester was melt blended with graphene nanoplatelets (GNPs) or with a 1:1 hybrid mixture of GNPs and carbon nanofibers (CNFs). The resulting nanocomposites exhibited enhanced thermal stability while their Young's modulus roughly doubled compared to pure PHA. The hybrid nanocomposites percolated electrically at lower nanofiller loadings compared to the GNP-PHA system. The electrical conductivity at 15 wt.% loading was ~ 6 times higher than the GNP-based sample. As a result, the electromagnetic interference shielding performance of the hybrid material was around 50% better than the pure GNPs nanocomposites, exhibiting shielding effectiveness above 20 dB, which is the threshold for common commercial applications. The thermal conductivity increased significantly for both types of bio-nanocomposites and reached values around 5 W K-1 m-1 with the hybrid-based material displaying the best performance. Considering the solvent-free and industrially compatible production method, the proposed multifunctional materials are promising to expand the range of application of PHAs and increase the environmental sustainability of the plastic and plastic electronics industry.

The synergistic effect of graphene nanoplatelets–montmorillonite hybrid system on tribological behavior of epoxy-based nanocomposites

Polymer nanocomposites have gained significant attention in wear application due to possessing distinctive wear resistance absent in polymers. In this study, the graphene nanoplatelets (GNPs) and montmorillonite (MMT) nanoclay were used to fabricate the hybrid epoxy-based nanocomposites. The synergistic effect of nanomaterials on and wear behavior of nanocomposites was studied at three different temperatures by using pin-on-disk tests. The most significant wear resistance was obtained at 0.5 wt% MMT-0.15 wt% GNPs nanocomposites at the temperatures below the Tg (25 °C and 60 °C) and at 0.3 wt% GNPs at the temperature above the Tg (95 °C) in comparison to the neat epoxy. It was determined that MMT with high hardness and GNPs with self-lubricant properties and increasing the Tg, improve the wear properties.

Flexible Gas Sensing Fibre Based on Bismuthous Sulfide Nanobelts-Sensitized Graphene Nanoplatelets (GNPs) Nanocomposites

Introduction Gas sensors with high flexibility and favorable extensibility have increasingly attractive prospects. Conventional rigid ceramics or semiconductor-based gas sensors have restricted flexibility and ductility, limiting their use in flexible devices and wearable electronics. Flexible gas sensors possess broad application prospects in the fields of wearable electronics, artificial intelligence, medical health, etc. Two-dimensional (2D) layered nanomaterials have attracted attention due to unique properties, which possess tunable band gaps and excellent mobility inherently. For example, graphene is usually utilized as gas sensing material due to high specific surface area and high carrier mobility [1]. However, the properties of pristine graphene nanoplatelets (GNPs) are influenced by significant adsorption of oxygen in an air environment, leading to instability and carrier mobility recession, limiting the practical application of GNPs gas sensors in atmosphere. The combination of quantum dots or nanobelts and 2D materials could build sensitized nanocomposites, which improves sensing performance of gas sensors. Flexible and ultrafast-response nitrogen dioxide (NO2) gas sensors based on cotton fibre that applies the mechanism of coupling and hydrogen bonding interaction were prepared by facile layered dip-coating methods. The gas sensors were fabricated utilizing cotton fibre as flexible substrate and bismuth sulfide (Bi2S3) nanobelts-sensitized GNPs nanocomposites as sensing layer. The flexible gas sensing fibre demonstrated ultrafast and recoverable response (67 s/45 s for 500 ppb gas), good reproducibility and mechanical robustness. The favorable sensing performance and high flexibility of fibre gas sensors will open potential prospects in intelligent sensing system and wearable electronics. Experimental Preparation of coupling reagent modified cotton fibre: The cleansed fibre substrate was first modified by 3-aminopropyl) triethoxysilane (APTES: coupling reagent) via dipping in APTES ethanol solution, and then rinsed with deionized water and dried in drying oven (100 ℃, 15 min). The organic functional group in coupling agent can be combined with the fiber substrate, meanwhile the silanoxy group in coupling agent is reactive with inorganic substances. When coupling agent is positioned between fiber substrate and gas sensing layer, bonding structure of cotton fibre-coupling agent-sensing layer can be formed. Synthesis of Bi2S3 nanobelts-sensitized graphene nanoplatelets nanocomposites: Solvothermal method was used for Bi2S3 nanobelts synthesis reported in literatures [2]. And GNPs/Sodium laurylsulfonate (SDL) ethanol solution (solution A) and Bi2S3/polyethylene glycol (PEG) ethanol solution (solution B) were prepared for next synthesis. Finally, solution A were injected into solution B under magnetic stirring for six hours to prepare Bi2S3/GNPs nanocomposites. Flexible gas sensor fabrication: The modified fibre was dipped in Bi2S3/GNPs solution for 30 min through dip-coating method, then treated with Pb(NO3)2 for surface ligand exchange to remove insulating organic ligands capping on Bi2S3 surface, lastly annealed in drying oven (60 ℃, 30 min). Results and Conclusions The stereoscopic illustration of electronic fibre gas sensor is shown in figure 1 (a). After two steps dip-coating processes, modified layer and outer Bi2S3/GNPs nanocomposites layer were successively coated on the surface of cotton fibre. Figure 1 (b) shows cross-section structure of fiber-based gas sensors, illustrating bonding structure of fibre-coupling agent-sensing layer. As for Bi2S3/GNPs nanocomposites layer, the intermolecular hydrogen bond [3] between sulfonic groups (-SO3H) of SDL and hydroxyl groups (-OH) of PEG could contribute to the interfacial adhesion between substrate and sensing layer (figure 1 (c)). For one thing, cotton fiber has advantages of large specific surface area and rich skeletal structure, which helps the combination of fiber skeleton and sensing materials. For another, Bi2S3-sensitized GNPs nanocomposites constructed an excellent receptor-transducer gas-sensing layer. Considering the dual-mode characteristics of fast carrier transfer on graphene and strong adsorption of gas molecules in Bi2S3 nanobelts, fiber-based gas sensors demonstrated ultrafast and recoverable response (67 s/45 s for 500 ppb gas), good reproducibility and mechanical robustness (figure 1(f-g)). The device showed excellent reversibility and negligible baseline drift following cycling responses (figure 1(g)). Compared with recently reported fibre-based gas sensors (Figure 1(h)), fibre-based gas sensors showed significantly enhanced response and recovery time. This work indicates that the flexible gas sensing fibre could be used to establish wearable electronics and real-time atmosphere information monitoring system.

Effect of GNPs content at various compaction pressures and sintering temperatures on the mechanical and electrical properties of hybrid Cu/Al2O3/xGNPs nanocomposites synthesized by high energy ball milling

Hybrid nanocomposites can be synthesized by high energy ball milling to form different compositions of Copper (Cu) strengthened with 10% alumina (Al2O3) and x graphene nanoplatelets (GNP) Cu–10%Al2O3/x GNPs (x = 0, 0.25, 0.5, 0.75, 1 wt%). Each mixture has been uniaxially compacted at pressures from 300 to 1200 MPa and sintered at three temperatures: 900, 950 and 1000 °C for 2hr. The effect of changing both compaction pressure and sintering temperature values for each mass fraction of the GNPs is investigated on the microstructural, mechanical characteristics, and electrical resistivity of the Cu–10%Al2O3/x GNPs hybrid nanocomposites. The results elucidate that the optimum mechanical and physical properties for producing the Cu–10%Al2O3/x GNPs nanocomposites are at compaction pressure of 700 MPa and sintering for 2 h at temperature of 1000 °C. Moreover, the addition of 0.5% of GNPs (Cu–10%Al2O3/0.5% GNPs) enhances the mechanical properties of the nanocomposites by 68% due to high mechanical properties and the reduction in the particle size of the graphene nanoplatelets. Whereas, increasing GNPs content more than 0.5%, leads to the reduction of the mechanical and physical properties of these composites due to the agglomerations of GNPs on the limits of the grain of Cu and Al2O3.

Polyethylene/Graphene Nanoplatelet Nanocomposite-Based Insulating Materials for Effective Reduction of Space Charge Accumulation in High-Voltage Direct-Current Cables

We have demonstrated a straightforward hydrophobic surface modification of graphene nanoplatelets (GNPs) through a defect-healing process to fabricate well-dispersed insulating low-density polyethylene (LDPE)/GNP nanocomposites and have confirmed their effective suppression of space charge accumulation. Without any organic modifiers, GNPs containing oxygen-based functional groups at the edges were successfully reduced at optimal high-temperature defect-healing condition and modified to have hydrophobic surface properties similar to those of the LDPE matrix. The degree of dispersion and the reproducibility of the mechanically melt-mixed LDPE/GNP nanocomposites were immediately analyzed by thickness-normalized optical absorption measurement. In the LDPE matrix, below the percolation threshold concentration, well-dispersed GNP fillers effectively acted as trapping sites under high electric fields, resulting in the successful suppression of packet-like space charge accumulation (field enhancement factor=1.04 @ 0.1 wt% LDPE/GNP nanocomposite).

The Effect of Graphene Nanoplatelets on the Wear Properties of High-Frequency Induction Sintered Alumina Nanocomposites

Alumina nanoparticles mixed with up to 1wt% graphene nanoplatelets (GNPs) were mixed by high-speed ball milling for 2 h at 350 rpm and sintered in a graphite die at 1650 °C for 20 min in an ultra-high-frequency induction heated system (UHFIHS) under uniaxial load in a vacuum chamber. The effect of different GNPs ratios on the microstructure, hardness and wear rate of alumina nanocomposites was examined. The results showed that the mechanical properties of Al2O3–GNPs nanocomposites gradually improved with GNP additions of 0.1 wt% to 0.6 wt%.

Effect of alkyl chain length grafted to graphene nanoplatelets on the characteristics of polypropylene nanocomposites

To improve the compatibility of graphene nanoplatelets (GNPs) to polypropylene (PP), alkyl chains were grafted to the GNPs’ surfaces by chemical reactions between alkyl amines and the corresponding functional groups of the GNPs. Hexylamine, dodecylamine, and octadecylamine were used respectively to prepare three different alkyl‐grafted GNPs (alkyl‐GNPs) with different alkyl chain lengths. Functional group analysis of the alkyl‐GNPs by Fourier transform infrared confirmed the alkyl‐grafting reaction. PP/alkyl‐GNP nanocomposites with 0.5 phr of hexyl‐, dodecyl‐, or octadecyl‐GNPs were prepared respectively by melt‐blending and compression molding and their mechanical and thermal properties and fracture surfaces morphology were investigated. With increasing alkyl chain length the flexural strength and melting temperature increased marginally but the flexural modulus, impact strength and storage modulus of the nanocomposites increased to a large extent. POLYM. ENG. SCI., 59:752–756, 2019. © 2018 Society of Plastics Engineers

Effect of graphene nanoplatelets content on the microstructural and mechanical properties of AZ80 magnesium alloy

In general, graphene nanoplatelets (GNPs) did not entirely imparted their extraordinary properties to the particulate magnesium matrix composites (PMgMCs) due to the poor wettability between GNPs and Mg matrix alloys as well as presence of agglomerated GNPs. Therefore, in this study, microstructure and mechanical characterizations were used to investigate effect of GNPs content on the microstructural and mechanical properties of AZ80 magnesium alloy. Current study explored the potential and mechanism of GNPs in improvement of mechanical properties of PMgMCs with insight of microstructure. Therefore, AZ80 reinforced by low contents of GNPs (0.1 and 0.6 wt%) were fabricated by rheo casting followed by hot extrusion. Simultaneously enhancement of tensile properties, the strengthening and the fracture strain efficiencies were achieved in AZ80/0.1GNPs composite by cost effectiveness and simple adaptability of manufacture method which results fairly uniform distribution of GNPs. The addition of 0.1 wt% GNPs led to grain refinement (~10%), dynamic recrystallization, stronger basal texture (~750%), more dissolution of β-eutectic phase (~66%) which results more dynamic precipitates (~70%) and reduction of yield asymmetry (~23%). Compared to the AZ80 alloy, the tensile and compressive yield strengths of AZ80/0.1GNPs composite were enhanced by 40% and 15%, respectively. In both tensile and compressive testes, the effective load transfer was the most important strengthening mechanism. Also, the tensile and compressive failure strains of AZ80/0.1GNPs nanocomposite were enhanced by 50% and 37%, respectively. The uniform dispersion of GNPs, increase of non-basal slip, grain refinement, lower eutectic content and smaller discontinuous intergranular precipitates increased failure strain.

High Velocity Impact Response of Basalt Fibers/Epoxy Composites Containing Graphene Nanoplatelets

The effects of adding surface modified graphene nanoplatelets (GNPs) in various weight percentages (0, 0.1, 0.2, 0.3, 0.4, 0.5 with respect to matrix) on the high velocity impact response of basalt fibers/epoxy composites were evaluated. High speed mechanical stirrer and ultrasonic waves were used for the dispersion of GNPs in the epoxy matrix, and hand layup method was utilized for the fabrication of the composite samples. High velocity impact testing was performed using a conical projectile. The results demonstrated that the maximum improvement in the impact limit velocity and energy absorption occurred in the 0.3 wt.% GNPs nanocomposite, i.e., 11 and 23 %, respectively. Also, the electron microscopy studies revealed that the addition of GNPs contributed in improving the impact properties by influencing the matrix and thus enhancing the interfacial characteristics between the basalt fibers and the matrix.

Graphene/poly(ethylene glycol) dispersions for fabrication of nanocomposites: effects of dispersion processing conditions

In the present research, ultrasonic exfoliation was employed to disperse graphene nanoplatelets (GNPs) in poly(ethylene glycol) (PEG) with two molecular weights. The GNP dispersions were added into poly(ethylene terephthalate) (PET) during injection molding to fabricate PET–GNP nanocomposites. The effectiveness of GNPs by weight (e) in the nanocomposite was evaluated by the improvement in elastic modulus. The e for the dispersion-dosed nanocomposite at 0.006 wt% was estimated to be 6.65 ± 4 and 20 ± 10 for PEG-600 and PEG-400, respectively. A review of sampled literature on PET nanocomposite elastic modulus improvement indicates that the effectiveness of GNPs obtained by dispersion dosing is significantly greater than other published results. Thus, the early promise of outstanding mechanical reinforcement by graphene in a polymer has been demonstrated.

Improved mechanical and wear properties of hybrid Al-Al2O3/GNPs electro-less coated Ni nanocomposite

Al was successfully reinforced with two ceramics Al2O3 coated Ni and graphene nanoplatelets (GNPs) coated Ni by electro-less deposition technique to form Al-Al2O3/x GNPs hybrid nanocomposite (x=0,0.2,0.6,1and 1.4%) with improved mechanical and wear properties. Compressive strength, hardness, wear properties and coefficient of friction were investigated. The results indicated that increasing GNPs volume fraction improves compressive strength, hardness and antifriction properties of composites significantly. In comparison with pure aluminum, 1.52- fold increases in the strength, 2.45-fold increase in the hardness and 19.2-fold decreases in the wear rate of Al-10%Al2O3/1.4%GNPs nanocomposite are achieved. This improvement is attributed to the remarkable mechanical strength and excellent self-lubrication of grapheme, the reduction of grain size during electro-less deposition process and the increased efficient stress transfer due to the curled structure of GNPs. Additionally, coating GNPs with Ni particles prevent the formation of Al3C4 intermetallic phase which lead to this large improvement in the wear rate. In comparison with the available results in the literature, electro-less coating of GNPs with Ni provides 2.1 times larger hardness than composite with uncoated GNPs.