Graphene Nanoplates Research Articles

Ballistic Impact Analysis of Graphene Reinforced Kevlar-29 and Kevlar-129 Laminated Composites

Aircraft goes through various high-speed hindrances like bird attacks, etc. Kevlar is increasingly used in the aviation industry to overcome such hindrances. Kevlar, an organic fibre from the family of aromatic polyamides consists of Kevlar 29, Kevlar 129, Kevlar 49 and Kevlar 149. This paper focuses on the use of Kevlar 29 and Kevlar 129 due to its low stiffness in comparison with Kevlar 49 and Kevlar 149. When pure Kevlar 29 and Kevlar 129 with 20 layers each are impacted with a 9g bullet at 900m/s velocity, the bullet perforates the laminate completely. Hence, the Kevlar layers are reinforced with graphene nanoplates. The bullet impact simulation of the ‘single-layer Kevlar 29 reinforced with single-layer graphene nanosheet’ (K29G), ‘single layer Kevlar 129 reinforced with single-layer graphene nanosheet’ (K129G), ‘double layer Kevlar 29 reinforced with double-layer graphene nanosheets’ (KK29GG) and ‘double layer Kevlar 129 reinforced with double-layer graphene nanosheets’ (KK129GG) is carried out using LS-DYNA. Maximum principal stress, effective stress, absorbed energy and displacement of the composite laminates (K29G, K129G, KK29GG and KK129GG) are used to compare the performance of these four laminates in the targeted applications. Due to its higher maximum principal stress, effective stress and lower displacement, the composite laminate K29G proves to be the apt laminate for its usage in aircrafts.

Boosting optical and electrical characteristics of polyvinyl alcohol/carboxymethyl cellulose nanocomposites by GNPs / MWCNTs fillers as an application in energy storage devices

The goal of this study is to manufacture polyvinyl alcohol and carboxymethyl cellulose films containing graphene nanoplates (GNPs)/MWCNTs to improve optical, dielectric, and electrical properties. The interaction between blend chains and GNPs/MWCNTs is emphasized by x-ray diffraction (XRD) analysis. The XRD indicated that the polymer blend's semicrystallinity decreased as the amount of GNPs/MWCNTs increased. In this study, ultraviolet (UV)-vis spectroscopy methods are used to examine the optical characteristics of the produced films in order to validate changes in the optical energy bandgap. The frequency-dependent AC conductivity of the nanocomposites films was used to analyze the dynamic behavior of ions of all the setup samples. The study presented the dielectric constant ε′ and dielectric loss ε″, as well as electric modulus spectra (M′ and M″) versus varied concentrations of frequency plots at room temperature. The electric modulus spectra (M″) were used to calculate the nanocomposites films' relaxation frequency (τs). The nanocomposites films ionic conductivity increased with GNPs/MWCNTs concentration, with the highest conductivity 4.53 × 10−4 at 30°C. The improved optical characteristics and AC conductivity enhance the application of such nanocomposite films in energy storage devices.

A variable stiffness adhesive enabled by joule heating effect

Smart adhesives have attracted great attention due to their reversible adhesion capacities and stimuli-responsive adhesion behavior. However, for most reported smart adhesive materials, it remains challenging to combine high conductivity, tunable adhesion, thermal healing, tunable mechanical strength, recyclability and reusability into one material. Herein, a new smart adhesive material composed of supramolecular polymer and graphene nanoplates was successfully designed and prepared. Strong and recycle adhesion performance was realized on various surfaces, with a maximum adhesion strength of 6.48 MPa on glass. In addition to excellent adhesion recyclability and reusability, this composite adhesive exhibits high mechanical strength, excellent plasticity and thermal healing properties. Through Joule heating effects, we can not only switch the adhesive between on and off states, but also tune the adhesion strength in a wide range. Based on these features, we designed a simple electric gripper which can raise and drop various objects simply by changing the applied voltages.

Influence of the Hydrophilic Surface of Nanofiber Support on the Performance of Hybrid Supercapacitors

Concerns associated with global warming and the depleting reserves of fossil fuels have highlighted the importance of high−performance energy storage systems (ESSs) for efficient energy usage. ESSs such as supercapacitors can contribute to improved power quality of an energy generation system, which is characterized by a slow load response. Composite materials are primarily used as supercapacitor electrodes because they can compensate for the disadvantages of carbon or metal oxide electrode materials. In this study, a composite of oxide nanoparticles loaded on a carbon nanofiber support was used as an electrode material for a hybrid supercapacitor. The addition of a small amount of hydrophilic FeN@GnP (Fe− and N−doped graphene nanoplates) modified the surface properties of carbon nanofibers prepared by electrospinning. Accordingly, the effects of the hydrophobic/hydrophilic surface properties of the nanofiber support on the morphology of Co3O4 nanoparticles loaded on the nanofiber, as well as the performance of the supercapacitor, were systematically investigated.

Improving the Electrochemical Performance of Pouch Cell Electric Double‐Layer Capacitors by Integrating Graphene Nanoplates into Activated Carbon

Herein, activated carbon (AC) is composited with multiple weight ratios of graphene nanoplates through a facile and scalable technique, including sonicating and vacuum mixing in a slurry to fabricate pouch cell electric double‐layer capacitors (EDLCs). Among the fabricated devices, the EDLC made of 2 wt% graphene/AC composite demonstrated the best electrochemical performance by enhancing the specific capacitance of AC EDLC from 27.3 to 39.3 F g−1 at 0.05 A g−1 current density. Moreover, the addition of graphene to AC leads to a more ideal capacitive behavior, reduction of charge transfer resistance (R ct) of the AC EDLC from 2.04 Ω to below 0.05 Ω, and the decrease of the ohmic drop at a current density of 2 A g−1 from 18.7% to 5.7%. 2 wt% graphene was considered as the optimum amount to be added to AC to increase the specific capacitance on average by 40% and improve the capacitance retention to 97% after 1000 cycles at 1 A g−1. Furthermore, the fabricated EDLC based on the optimum ratio of graphene to AC possessed satisfactory energy densities of 13.7 and 8.3 Wh kg−1 at 50 and 2000 W kg−1 power densities, respectively.

Al 5251-based hybrid nanocomposite by FSP reinforced with graphene nanoplates and boron nitride nanoparticles: Microstructure, wear, and mechanical characterization

Abstract The strength and wear resistance of aluminium alloys must be improved to enhance their usage in lightweight constructions. Thus, in this study, graphene nanoplates (GNPs) and boron nitride (BN) nanoparticles were reinforced into the Al 5251 aluminium alloy by friction stir processing (FSP). The Al 5251 aluminum alloy sheets were patterned with holes and filled by mono GNPs, mono BN nanoparticles and a hybrid of BN nanoparticles and GNPs. The microstructure, wear, and mechanical properties of the as-received, after FSP, and the manufactured surface nanocomposites were analysed. Wear tests were performed using two methods: weight loss and volume loss methods. FSP led to four times grain refinement. Due to the Zener pinning effect, the reinforcement nanoparticles improved the grain refinement effect by seven times decrease in the mean grain size. The wear rate by volume and weight loss with reinforcing BN nanoparticles decreased by 160 and 1,340%, respectively. Note that the GNP reinforcement insignificantly improved the wear resistance and hardness compared with the BN nanoparticles. The hardness was increased by 50, 120, and 80% by reinforcing the Al 5251 alloy with GNPs, BN, and a hybrid of BN nanoparticles and GNPs, respectively. The nanocomposite reinforced with GNPs exhibited superior mechanical properties compared to the other nanocomposites.

Novel phenomena of graphene secondary dispersion and phase transformation in selective laser melting of 15-5PH/graphene composites

15-5PH, a martensitic, precipitation hardening stainless steel, can easily form a martensite structure during rapid solidification, especially in the selective laser melting (SLM) process. In our study, the 15-5PH/Gr composites with different mass ratios (0 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%) of graphene nanoplates (GNPs) were successfully prepared using SLM technology. Through the observation of optical microscopy images and Raman spectra, it is discovered that the GNPs are uniformly dispersed in the 15-5PH/Gr composites. Based on this phenomenon, a flow model is established to explain the process of the secondary dispersion of the GNPs in the molten pool at high temperatures, and then we come up with a mechanism for it. Besides, it is found that GNPs have a strong inhabiting effect on phase transformation of 15-5PH/Gr composites during the rapid solidification of the SLM process, and the inhibition will be enhanced as the GNPs content increases. The mechanical properties of metal matrix composites (MMCs) are significantly influenced by the changes in phase and additive content. According to the mechanical property tests on the 15-5PH/Gr composites, it is found that their ductility and impact toughness have maximum values of 41.1 ± 1.3% and 194.9 ± 3.1 J/cm 2 respectively, and the friction coefficient of the 15-5PH/Gr composites have a minimum value of 0.34. Compared with the SLM-ed 15-5PH, the improvement of mechanical properties of the 15-5PH/Gr composites on ductility, impact toughness and wear resistance are increased by 130.9%, 97.3% and 45.2% respectively.

Deformation strengthening mechanism of in situ TiC/TC4 alloy nanocomposites produced by selective laser melting

In this study, in situ -formed TiC/TC4 alloy nanocomposites were fabricated using the selective laser melting (SLM) process with TC4 and graphene nanoplates (GNPs) powders, and the deformation strengthening mechanism of the Ti matrix reinforced with TiC nanoparticles was investigated. The results from microstructure observation and molecular dynamics simulations revealed that the appearance of nanoscale TiC reinforcement favoured the formation of deformation twinning, which promoted that the atoms of the TiC/TC4 alloy nanocomposites maintained an orderly arrangement during deformation. Further, a dual strengthening mechanism of that the severe lattice distortion at the interface formed by different orientations and the deformation twinning suppressed the movement of the dislocation has been put forward to describe the occurring of dislocation pinning effects. All these findings provide a feasible perspective to strengthen mechanical performance by addressing the long-standing issue in the SLM of TC4 alloy nanocomposites. • We propose the molecular dynamics (MD) simulation and TEM characterization for TiC/TC4 alloy nanocomposites. • Our approach makes the strengthening mechanism of deformation twins more intuitively by MD simulation. • We test and verify the MD simulation results, including TiC formed in situ and deformation twins.

Construction of 3D Conductive Network in Liquid Gallium with Enhanced Thermal and Electrical Performance

AbstractThis paper reports the generation of 3D thermal and electrical conductive graphene network in gallium‐based liquid metal (LM) via a simple one‐step ball‐milling approach. In this work, 2D graphene nanoplates and their derivatives were employed to construct 3D thermal and electrical conductive filler networks. It is demonstrated that the obtained composite exhibits the highest 3D thermal conductivity (44.6 W m−1 K−1) among the other gallium‐based LM composites with 2D inorganic nanofillers and distinguished electrical conductivity (8.3 S µm−1) among gallium‐based LM composites at present. The enhanced thermal conductivity and wettability of gallium‐based composite lead to its beneficial usage as thermal interface materials with exquisite texture for LED chip heat dissipation. The electrochemical and magnetic experiments confirm that these LM‐based composites can also be controlled under external electrical or magnetic field, which potentially can help extend their application in external field‐driven systems. The findings of this work offer new insight in designing LM‐based composites with enhanced thermal, electrical, and magnetic properties for a wide range of applications, including thermal management systems, 3D printing, flexible conductors, soft robotic systems, and wearable energy technologies.

Flexible Copper–Graphene Nanoplates on Ceramic Supports for Radiofrequency Electronics with Electromagnetic Interference Shielding and Thermal Management Capacity

Flexible electronics for harsh and hazardous environments could offer a broad range of technological applications from conformal structural health monitoring, hypersonics, to telecommunication syst...

Highly efficient and biodegradable flexible supercapacitors fabricated with electrodes of coconut-fiber/graphene nanoplates

We report the fabrication and electrochemical characterization of biodegradable and flexible supercapacitors (SCs). The conductive electrodes of these SCs were pieces of compacted coconut fibers coated by graphene nanoplates. An oral electrolyte solution (OES) and rice paper were used as electrolyte and separator, respectively. The SCs’ encapsulation was made of gelatin/pectin. According to the electrochemical tests, the maximum capacitance and specific energy of the cell made with the biodegradable components were 670.8 F g−1 and 134.2 Wh kg−1, respectively. After adding MgTiO3 nanoparticles (NPs) to the anode, both, the capacitance and specific energy were enhanced by ≈37% and by ≈20%, respectively. For comparison purposes, the OES electrolyte was substituted by a conventional acidic electrolyte (PVA/H3PO4) in the SCs, but the capacitance and specific energy obtained were lower (175.9 F g−1 and 35.2 Wh kg−1). Interestingly, the biodegradable cells exhibited very long discharge times of 550–600 min and a stable output voltage in the range of 0.54–0.71 V, which has not been observed previously for biodegradable SCs. The SCs made with MgTiO3 NPs stored charge by redox reactions and the redox centers were oxygen vacancies (defects), Mg2+/Mg0 and Ti3+/Ti4 (the presence of such centers was confirmed by x-ray photoelectron spectroscopy, Raman and absorbance measurements). In general, we demonstrated that the biodegradable SCs are sustainable/eco-friendly energy sources that are promising to substitute the conventional technologies of Li or alkaline batteries made with toxic/corrosive components that contaminate the environment.

The tribological behavior of different carbon nanomaterials-reinforced the titanium (TC21) matrix composite

This study examined the effects of different carbon nanomaterials on the mechanical and tribological properties of titanium matrix composites. Carbon nanotubes (CNTs), graphene nanoplates (GNPs) and graphene oxide nanoplates (GOs) reinforced Ti–6Al–2Sn–2Zr–3Mo–1Cr–2Nb–Si (TC21) titanium matrix composites were prepared by spark plasma sintering. In the three carbon nanomaterials, CNTs react with the TC21 matrix to form TiC, while GNPs and GOs react with the TC21 matrix to form a TiC coated GNPs/GOs sandwich structure, and the formation of TiC phase promotes the interfacial bonding of the composite. GOs/TC21 composites exhibit better strength and wear resistance than the other two composites. GOs/TC21 composite exhibits excellent mechanical properties, i.e., yield strength of 1043 MPa, the ultimate tensile strength of 1183 MPa and an elongation about of 8%. The wear loss of GOs/TC21 composite decreased by 24.2% compared to that of the TC21 alloy. The superior mechanical and tribological performances of GOs/TC21 composites are attributed to the TC21 matrix strengthening brought by the TiC particles/TiC coated GNPs/GOs sandwich structure and the lubricating properties of the residual GOs, which demonstrates that GOs is an ideal filler for TC21 alloy.

Bending, buckling and Vibrations Analysis of the graphene nanoplate using the modified couple stress theory

In this paper using the modified couple stress theory, to study the bending, buckling and vibration characteristics of the rectangular Mindlin's nanoplates with graphene material was investigated. With the aim of considering the effects of small scales, the modified couple stress theory, which has only one parameter of length scale and also was presented by Yang in 2002, was used. In the modified couple stress theory; the strain energy density is a function of the components of the strain tensor, curvature tensor, stress tensor and the symmetric part of the couple stress tensor. After obtaining the strain energy, external work, and buckling equation and placing them in the Hamilton's equation, the basic and auxiliary equations of the nanoplates were obtained. Then, by applying boundary and force conditions in the governing equations, the bending, buckling and vibration of the rectangular graphene nanoplates with thickness h and simply-supported conditions were explored. Also, the solution method was the Navier's solution.

Highly sensitive and flexible tactile sensor with truncated pyramid-shaped porous graphene/silicone rubber composites for human motion detection

This paper presents a novel highly sensitive and flexible tactile sensor based on the fabrication of truncated pyramid-shaped porous graphene nanoplate (GNP)/silicone rubber (SR) composites as the sensing material. The designed tactile sensor has 3 × 3 (=9) sensing units, each unit has three layers: top cover layer with upper electrodes, middle truncated pyramid-shaped porous composite sensing materials, and substrate layer with bottom electrodes. The fabrication processes to make the truncated pyramid-shaped porous piezoresistive sensing material and tactile sensor were developed. The prepared porous GNP/SR composites possess extremely high sensitivities of 8.45 kPa−1 at 0–55 kPa and 195.02 kPa−1 at 55–80 kPa for pressure sensing, its Young's modulus is generally low (∼85.72 kPa), and can endure large strain over 60%. The sensing performances of the fabricated tactile sensor were also characterized, results show that the tactile sensor has high sensitivity, good dynamic response, and repeatability under cyclic pressure sensing. Human body wearing experiments were performed and results demonstrate that the developed tactile sensor was able to detect the distributed motion signals as well as human physiological signals such as pulse accurately, indicating that the proposed tactile sensor has great potential for human motion and health monitoring.

Performance Evaluation of Asphalt Mixtures with Graphene Nanoplates and Carbon Black

Performance Evaluation of Asphalt Mixtures with Graphene Nanoplates and Carbon Black

Influence of graphene nanoplates and multiwall carbon nanotubes on rheology, structure, and properties relationship of poly (lactic acid)

Influence of graphene nanoplates and multiwall carbon nanotubes on rheology, structure, and properties relationship of poly (lactic acid)

Modeling and Simulation of Fabricated Graphene Nanoplates/Polystyrene Nanofibrous Membrane for DCMD.

Membrane distillation is an active technique that provides pure water with very good rejection and could be applied to water of extremely high salinity. The low productivity of membrane distillation needs intensive efforts to be competitive with other desalination techniques. In this current study, a composite (PS/GNP) membrane, which is composed of polystyrene (PS) based and 0.25% weight percent graphene nanoplates (GNP) has been fabricated via electrospinning and compared with the blank PS membrane. SEM, FTIR, contact angle and porosity characterization have been performed, and the results show that the validity of the predefined conditions, and the contact angle of the composite membrane, which is found to be 91.68°, proved the hydrophobic nature of the composite membrane. A numerical simulation using Ansys 2020 software has been introduced to study the performance of the fabricated composite membrane when used in direct contact membrane distillation (DCMD). The numerical model has been validated with experimental work from the literature and showed an excellent match. The blank PS and composite PS/GNP membranes have been investigated and compared at different operating conditions, i.e., hot water supply temperature and system flow rate. The results show that the composite PS/GNP membrane outperforms the blank PS membrane at all studied operating conditions.

Mechanochemical functionality of graphene additives in ultralow wear polytetrafluoroethylene composites

Poly-tetrafluoroethylene (PTFE) is a well-known solid lubricant, but its poor wear resistance limits its tribological applications. Certain carbonaceous fillers reduce PTFE wear rate by up to 4000-fold with no sacrifice of the friction coefficient; whereas the responsible mechanisms remain unclear. We systematically studied the effects of three graphene fillers with different aggregate strengths (graphene nanoplates, few-layer graphene and single-layer graphene) on the wear resistance of graphene-PTFE composites. The results found (1) graphene of weak aggregate strength outperform that of strong aggregate strength by 100 times in wear reduction, (2) strong correlations between wear rate, tribofilm carboxylate signal intensity and filler-matrix area per unit composite mass. The carboxylate signals likely correspond to chemical bonding between mechanochemically degraded PTFE, graphene and the steel counterface within highly crosslinked and adherent transfer films and worn polymer surfaces. Results in this study support two independent (primary versus secondary) wear reduction hypotheses in literature which were further backed by DFT simulations of filler-matrix interactions, TEM/EDS analysis of wear debris, SEM/EDS images of the polymer surfaces, and environmental test results in a dry argon (Ar) atmosphere. The results of this paper are also of instructive value for the development of solid lubricants with highly controllable wear characteristics.

Synthesis of Poly(Methyl Methacrylate) Reinforced by Graphene Nanoplates

Graphene nanoplatelets (GNPs) was used as a nanofiller in Poly(methyl methacrylate) (PMMA) synthesized by the Atom Transfer Radical Polymerization (ATRP) method. The first step in the synthesis of the PMMA/GNPs was the dispersion of GNPs in the PMMA liquid monomers by combining the solutions so that GNPs had superior mechanical properties, thermal stability, and electrical conductivity also lower density of mass. Then the crosslinked PMMA/GNPs nanocomposite samples were synthesized by using the in-situ polymerization method. However, there was a challenging technical problem in the application of GNPs (at a large amount) in the polymer. For the purpose of benefiting from the advantageous properties of GNPs (especially in bulk quantities) at PMMA, the major problem at the synthesis of PMMA/GNPs nanocomposite was the GNPs dispersion in the polymer matrix. This research has focused on solving that dispersion problem with the aim of enhancing the mechanical properties of the nanocomposite by utilizing the ATRP method as the effective production technic. The structural characterization of PMMA/GNPs nanocomposite was performed for the examination of the integration of GNPs in PMMA. The surface morphology of the nanocomposite was analyzed using SEM images. X-Ray Diffraction (XRD) as a non-destructive test method was used to examine the changes in the crystalline properties of the nanocomposite structure with the rise of the GNPs amount in PMMA. The bonding interactions with each other were investigated by using Raman analysis.

Carbon welding on graphene skeleton for phase change composites with high thermal conductivity for solar-to-heat conversion

Advanced phase change materials (PCMs) with three-dimensional (3D) thermal conductive skeletons reveal the promising prospect in the thermal management of lithium battery. However, the high filler-to-filler interfacial thermal resistance (ITR) arising from the weak interfacial contact connection in 3D skeleton is still challenging. Herein, we demonstrate a “carbon welding” strategy for reducing the filler-to-filler ITR in 3D graphene skeleton by achieving the lattice connection between contact graphene. Typically, the ordered 3D graphene skeleton was constructed by unidirectionally ice template assembling graphene nanoplates (GNP) with the assistance of poly (amic acid) (PAA). Imidization and carbonization treatments were employed to weld the adjacent GNP in 3D skeleton. The similar lattice structure of carbonized polyimide (PI) and graphene can result in the significant reduction of phonon scattering and ITR at these contact areas. After impregnation with polyvinyl alcohol (PEG), the high-performance PCMs with high-efficient phonon transmission expressway were obtained. As expected, the prepared composites reveal the high thermal conductivities with a maximum value of 7.032 W m−1 K−1 at ~11.6 vol% GNP, which is more than two-fold than that of the composite with uncarbonized skeleton. Finite element simulation and nonlinear model analyses confirm that the reduced filler-to-filler ITR in skeleton is the main reason for the improving thermal conductivity. In addition, the presence of 3D graphene skeleton can effectively avoid the leakage during solid–liquid phase change, and significantly improve the shape stability of the PCMs. At the same time, the graphene skeleton can endow the PCM with an excellent solar-to-heat conversion performance, which ensure a wide range of application in actual environment.