Effect Of Graphene Nanoplatelets Content Research Articles

The Effect of Graphene Nanoplatelets Content on the Hardness of Mg6%Zn0.2%Mn Composites

The effect of graphene nanoplatelets (GNPs) content on the hardness of magnesium-based composites was studied. A magnesium-based composite, Mg6%Zn0.2%Mn with graphene nanoplatelets (GNPs), was fabricated via powder metallurgy process at room temperature and compressive pressures of 50kN for 20 minutes, which was then sintered at 500°C for 2 hours. It produced significant grain refinement microstructure. The change in microstructure was examined by 3D microscope analysis, and the hardness value was evaluated using the Vickers microhardness apparatus. This study demonstrated the importance of GNPs reinforcement with zinc and manganese for microhardness analysis in the sintered Mg-based GNPs composites. It also portrayed their influence on grain refinement of the microstructure. The hardness results agreed with the microstructure results, proving that the presence of GNPs increases the hardness of the Mg-based composites.

Investigation of the effect of Graphene Nanoplatelet content on Flexural Behavior, Surface Roughness and Water Absorption of a Graphene Nanoplatelets Reinforced Epoxy Nanocomposites

In the present work, the effect of Graphene nanoPlatelets (GnP) content on the flexural, surface roughness, and water absorption behavior of a GnP reinforced epoxy composite was investigated. Different wt.% of GnP (0.25, 0.5, 0.75, and 1 wt.%) was added into the epoxy matrix through the sonication method followed by the ball milling. The results indicate a significant enhancement in the flexural properties of the epoxy nanocomposite with the addition of GnP in the epoxy matrix. The optimum enhancement in the properties was obtained at 0.25 wt.% GnP incorporated epoxy composites. The increase in flexural strength and flexural modulus results were noticed as 42.7% and 49.2% when compared with neat epoxy. The surface roughness value for the loading of 0.25 wt.% of GnP into the epoxy showed a drop of 48.7% when compared with that of the neat epoxy sample. The loading of 0.25 wt.% of GnP into the epoxy also reduces the water absorption from 0.125% for the neat epoxy sample to 0.067% for the composite sample. The Scanning Electron Microscope (SEM) images of the fractured surface (flexural samples) of the GnP embedded epoxy composites show the river like pattern, which is the result of the better dispersion of the GnP in the epoxy matrix and thus shows improvement in flexural behaviour of such composite materials.

On the Multi-Functional Behavior of Graphene-Based Nano-Reinforced Polymers.

The objective of the present study is the assessment of the impact performance and the concluded thermal conductivity of epoxy resin reinforced by layered Graphene Nano-Platelets (GNPs). The two types of used GNPs have different average thicknesses, <4 nm for Type 1 and 9–12 nm for Type 2. Graphene-based polymers containing different GNP loading contents (0.5, 1, 5, 10, 15 wt.%) were developed by using the three-roll mill technique. Thermo-mechanical (Tg), impact tests and thermal conductivity measurements were performed to evaluate the effect of GNPs content and type on the final properties of nano-reinforced polymers. According to the results, thinner GNPs were proven to be more promising in all studied properties when compared to thicker GNPs of the same weight content. More specifically, the glass transition temperature of nano-reinforced polymers remained almost unaffected by the GNPs inclusion. Regarding the impact tests, it was found that the impact resistance of the doped materials increased up to 50% when 0.5 wt.% Type 1 GNPs were incorporated within the polymer. Finally, the thermal conductivity of doped polymers with 15 wt.% GNPs showed a 130% enhancement over the reference material.

Characterizing Biaxially Stretched Polypropylene / Graphene Nanoplatelet Composites

In this work, polypropylene (PP) nanocomposites containing different weight concentration of graphene nanoplatelets (GNP) were prepared by melt-mixing using an industrial-scale, co-rotating, intermeshing, twin-screw extruder. The materials were then compression moulded into sheets, and biaxially stretched at different stretching ratios (SRs) below the PP melting temperature. The effects of GNP content and biaxial stretching on the bulk properties of unfilled PP and PP/GNP nanocomposites have been investigated in details. Results show that the addition of GNP (&amp;gt;5wt%) can lead to electrically conductive composites due to the formation of percolation network. The GNP have led to increased polymer crystallinity and enhanced materials stiffness and strength. Biaxial stretching process further enhances the materials mechanical properties but has slightly decreased the composites electrical conductivity. The PP/GNP nanocomposites were also processed into 3D demonstrator parts using vacuum forming, and the properties of which were comparable with biaxially stretched composites.

Enhanced thermally conductive and thermomechanical properties of polymethyl methacrylate (PMMA)/graphene nanoplatelets (GNPs) nanocomposites for radiator of electronic components

In this work, multi-layer hot pressing (MLHP) method was used to prepare the graphene nanoplatelets (GNPs) filled polymethyl methacrylate (PMMA) composites. Effect of GNP content on the viscoelastic behavior and thermomechanical properties of composites was studied via rheometer, scanning electron microscope (SEM), infrared thermal imaging (ITI) and dynamic mechanical thermal analysis (DMTA), etc. According to dynamical rheological testing, thermorheological complexity was clearly displayed at elevated GNP content, based upon flow activation energy (Ea) and time-temperature superposition (TTS) principle. The infrared thermal imaging (ITI) indicated that a filler conductive network was gradually formed with increasing filler content. The average heating rate of the samples increased from 0.74 to 0.92 °C/s. The Agari model was found to fairly interpret the variation of thermal conductivity as a function of GNP loading, which agreed well with SEM observation and indicative of the formation of a GNP network structure. Dynamic thermomechanical properties of the composites were heavily influenced by the temperature distributions within the samples. The addition of GNP increased the glass transition temperature of PMMA from 116.7 to 125.9 °C, which favored enhanced thermophysical properties of PMMA. The prepared composites in this work showed wonderful mechanical properties even at relatively high temperatures (e.g., having storage modulus of 1.3–1.9 GPa and yielding strength more than 58.0 MPa at 50 °C). The current work is practically significant for further expanding the application range of PMMA/GNP nanocomposites.

Effects of graphene nanoplatelets on bio-based shape memory polymers from benzoxazine/epoxy copolymers actuated by near-infrared light

Novel near-infrared (NIR) light-induced bio-based shape memory polymers (SMPs) were prepared from copolymers of vanillin/furfurylamine-based benzoxazine monomer (V-fa monomer) and epoxidized castor oil (ECO). Incorporation of graphene nanoplatelets (GNPs) as photothermal fillers into the copolymers provided shape memory properties under near-infrared (NIR) light actuation. The effects of GNP content on photothermal, thermal, dynamic mechanical, morphology, and shape memory properties of the bio-based benzoxazine/epoxy copolymers (V-fa/ECO copolymers) were investigated. The results showed that the addition of GNPs significantly improved the photothermal, thermal, and dynamic mechanical properties of the copolymers. The uniform dispersion of 3 wt% GNPs in the V-fa/ECO copolymers resulted in the highest shape memory performance with shape fixity of 92% and shape recovery of 99% upon NIR light actuation. The recovery time decreased with the increment of GNP content, and the V-fa/ECO copolymers filled with GNPs displayed good execution in the repeated fold-deploy, in which the shape fixity and shape recovery values were close to the original specimen. Therefore, the outstanding properties of V-fa/ECO copolymers filled with GNPs had a potential to be excellent SMPs under NIR actuation.

Extrusion and characterization of aluminum/graphene composites

Since its first synthesis in 2004 graphene was characterized intensively and exceptional properties in terms of e.g. mechanical strength, stiffness and electrical as well as thermal conductivity were revealed. These properties make graphene very attractive to be applied as additive in composite materials e.g. to increase strength and conductivity compared to the pure matrix material. In this study graphene nano platelets (GNP) in contents of 0. 5%, 1.0 % and 1.5 % were added to pure (99.7 %) aluminum powder and dispersed via EIRICH mixer method. This method is very appealing since homogenous mixtures can be achieved in significantly lower time when compared to e.g. the ball milling process. After subsequent cold compaction the composite materials were extruded with three different extrusion ratios. The influence of GNP content and extrusion ratio on the specific extrusion pressure is characterized as well the resulting rod surface quality, respectively. The effects of GNP content and extrusion ratio on homogeneity of graphene dispersion in the aluminum matrix, the relative density of the composite as well as hardness were also investigated.

Extrusion and characterization of aluminum/graphene composites

Since its first synthesis in 2004 graphene was characterized intensively and exceptional properties in terms of e.g. mechanical strength, stiffness and electrical as well as thermal conductivity were revealed. These properties make graphene very attractive to be applied as additive in composite materials e.g. to increase strength and conductivity compared to the pure matrix material. In this study graphene nano platelets (GNP) in contents of 0. 5%, 1.0 % and 1.5 % were added to pure (99.7 %) aluminum powder and dispersed via EIRICH mixer method. This method is very appealing since homogenous mixtures can be achieved in significantly lower time when compared to e.g. the ball milling process. After subsequent cold compaction the composite materials were extruded with three different extrusion ratios. The influence of GNP content and extrusion ratio on the specific extrusion pressure is characterized as well the resulting rod surface quality, respectively. The effects of GNP content and extrusion ratio on homogeneity of graphene dispersion in the aluminum matrix, the relative density of the composite as well as hardness were also investigated.

Electromagnetic wave-absorbing properties of graphene nanoplatelets - calcium sulfoaluminate cement - based composites

In this paper, graphene nanoplatelets [GNPs] in calcium sulfo-aluminate cement-based composites were prepared. The effects of graphene nanoplatelets content and sample thickness on the absorbing properties of composites were studied and the related mechanism was investigated. The experimental results have shown that the sample with a thickness of 25mm exhibited good electromagnetic wave [EMW] absorption, when the content of gra-phene nanoplatelets is 0.06%. The minimum refl ectivity is -30.8 dB at 8.7 GHz, and the cumulative bandwidth [&lt; -5 dB] is 9.5 GHz. When the content of GNPs is increased to 0.08%, the EMW ab-sorption property of the sample does not enhance remarkably. The absorbing property can be improved by adjusting the thickness of sample. The specimen with a thickness of 35 mm performed excellent broadband absorption characteristics.

Effect of Graphene Nanoplatelets Content on the Mechanical and Wear Properties of AZ31 Alloy

Graphene, as a rising-star materials, has attracted interest in fabricating lightweight self-lubricating metal matrix composites with superior mechanical and wear properties. In this work, graphene nanoplatelets (GNPs) reinforced AZ31 alloy composites were fabricated by a powder metallurgy technique and then a hot extrusion. The effects of GNPs content (0.5, 1.0, and 2.0 wt.%) on the microstructures, mechanical properties, and wear performance of the extruded GNPs/AZ31 composites were studied. It was found that the addition of GNPs resulted in a weakened basal plane texture and grain refinement of the AZ31 matrix metal. Less than 1.0 wt.% GNPs in GNPs/AZ31 composites resulted in the enhancement in both Vickers hardness and tensile yield strength with acceptable elongation. The Vickers hardness and tensile yield strength of 1.0GNPs/AZ31 composite increased by 4.9% and 9.5% respectively, compared with the unreinforced AZ31. Moreover, the elongation of the composites was about the same as the AZ31 base alloy. Both the friction coefficient and the wear mass loss continuously decreased with the increasing GNPs content, which exhibited a self-lubricating effect. The relationship of the friction coefficient and wear mass loss with the GNPs content could be modeled in terms of the Holliday model and the exponential decay model, respectively. The worn surface morphology revealed that adhesive wear and abrasive wear simultaneously acted in AZ31 alloy. Nevertheless, abrasive wear became the dominant wear mechanism in the GNPs/AZ31 composites.

Tribological Properties of Different Types of Graphene Nanoplatelets as Additives for the Epoxy Resin

The use of graphene nanoplatelets for several purposes such as barrier properties and structural health monitoring is widely studied in polymer-based coating technology. Nevertheless, their extremely good effect on wear resistance makes them particularly interesting for coating technology. The effect of graphene nanoplatelets addition on the wear behaviour of an epoxy resin was analysed. The effects of graphene nanoplatelets content (0–8 wt.%), morphology and functionalization in wear behaviour were analysed by evaluating the main wear parameters of the nanocomposites studied. The morphology of the wear surfaces was analysed by scanning electron microscopy (SEM) and 3D optical profilometry in order to evaluate the mechanism and severity of wear. The results showed that the wear behaviour of the epoxy resin improved considerably with the addition of graphene, especially for higher contents. Moreover, as the wear mechanism depends on the morphology of graphene nanoplatelets, it was concluded that the proper selection of graphene can be made depending on the chosen application.

Influence of graphene content and nickel decoration on the microstructural and mechanical characteristics of the Cu/Sn–Ag–Cu/Cu soldered joint

In this research article, lead-free nanocomposite soldering is assessed by using the eutectic composition of Sn-3.5Ag-0.7Cu (SAC, wt%) solder alloy as the matrix and graphene nanoplatelets (GNPs) as the reinforcing agent. Powders of these materials are mixed in a mechanical milling system, then compacted, and sintered before application. The effects of GNPs content with different amounts of 0.05, 0.1, and 0.2wt% are examined to prepare nanocomposite solders as compared to the SAC solder alloy. Furthermore, to improve the metallurgical compatibility between the graphene and SAC solder matrix, the surface of GNPs was decorated by nickel particles using electroless plating techniques before incorporation. After that, the solderability of these prepared lead-free nanocomposite solders is investigated on the copper substrate. As the main result, the formation of the intermetallic compound (IMC) layers at the interface between the Cu-substrate and solder material was found very determinative to control the mechanical performance of soldered joints during lap-shear testing. The content of GNPs and Ni-coating modification strongly affected the morphology and growth of IMC layers at the interface. By increasing the amount of GNPs up to ∼0.2wt% and using Ni-coating, the growth of IMC layers was considerably suppressed, leading to a significant improvement of the joint strength up to ∼27%, despite a reduction of ∼50% of the ductility. Furthermore, isothermal aging at 150°C up to 100h resulted in a remarkable increase in the shear strength (∼45%) and elongation to failure (∼19.9%) through controlling the growth of the IMC layers at the interface.

Development of waste tire‐derived graphene reinforced polypropylene nanocomposites with controlled polymer grade, crystallization and mechanical characteristics via melt‐mixing

AbstractIn the present work, single layer graphene nanoplatelets (GNPs) derived from waste tires by recycling and upcycling approaches were integrated in homopolymer (Homo‐) and copolymer (Copo‐) polypropylene (PP) matrices by fast and efficient mixing in the melt phase. The effect of GNP content on crystallization and mechanical behaviors was investigated in detail at different loading levels. Regarding isothermal and non‐isothermal crystallization experiments, GNPs significantly accelerated the nucleation and growth of crystallites, and the crystallization degree in Homo‐PP nanocomposites was slightly higher than that of Copo‐PP based nanocomposites. Also, there was significant improvement in mechanical and thermal properties of GNP reinforced polymers compared to neat polymers. As the GNP concentration increased from 1 to 5 wt%, there was a gradual increase in flexural modulus and strength values. In tensile tests, an increase in GNP content in both polymer grades led to a slight increase in yield strength coming from the proper distribution of nano‐reinforcement by creating stress concentration sites. After the yield point, Homo‐PP based nanocomposites showed higher strain hardening than GNP reinforced Copo‐PP owing to a high crystallization degree and linear chains of Homo‐PP. This work showed that functionalized graphene can act as both nucleating and reinforcing agent in the compounding process and its exfoliation through polymer chains is much better in homopolymers at a faster and high shear rate. © 2020 Society of Chemical Industry

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.

Magnesium Phosphate Cements/GNPs Composites by Combustion Synthesis and Acid-Base Reaction

Magnesium phosphate cements (MPC)/graphene nanoplatelets (GNPs) composites were fabricated by combustion synthesis and acid-base reaction. MgO/GNPs mixture powders were obtained by the combustion reaction between Mg powders and CO2 gas. The composites were prepared by mixing MgO/GNPs mixture powders with potassium dihydrogen phosphate (KH2PO4) using borax as retarder. The effect of GNPs content on mechanical and functional properties of the prepared MPC/GNPs composites was investigated. The results show that this MPC/GNPs cements mainly consisted of MgO and KMgPO4•6H2O. Moreover, the crystallinity of KMgPO4•6H2O in lower surface is better than the upper surface due to the difference of temperature. With incorporating small amounts of GNPs into MPC, the spectral absorptivity of the composite was improved to 0.95 in most spectral regions. Nevertheless, the compression strength shows little change with changing the GNPs content, which may be attributed to use coarse MgO powder as reactant. In virtue of short processing time and homogeneous distribution of GNPs, the novel fabrication provides a new route for preparing GNPs-cement based composites.

Development of Novel AlSi10Mg Based Nanocomposites: Microstructure, Thermal and Mechanical Properties

Al matrix nanocomposites are interestingly employed in the automotive, military, aerospace and electronics packaging industries. In this study, Graphene Nanoplatelets (GNPs) reinforced AlSi10Mg nanocomposites were produced via powder metallurgy. The effect of GNPs content on density, microstructure and mechanical characteristics of the AlSi10Mg/GNPs nanocomposites was investigated systematically. To this aim, AlSi10Mg/GNPs nanocomposites reinforced with 0.5, 1.0 and 2.0 wt.% of GNPs were produced by wet mixing method following by hot compaction at 600 °C. To evaluate the effect of GNPs on mechanical properties of the as-fabricated nanocomposite, Vickers hardness and tensile properties of composites analyzed at room temperature. According to the results, it was found that the fabrication of AlSi10Mg/GNPs nanocomposites is faced with several challenges such as agglomeration and non-uniform dispersion of GNPs that should be addressed to achieve the desirable thermal and mechanical properties. For instance, surprisingly, it is revealed that the mechanical and thermal properties of nanocomposites were deteriorated in the presence of a high quantity of GNPs (&gt;1.0 wt.%), which can be attributed to the GNPs agglomeration and accordingly introduction of internal porosity in the nanocomposite. The relatively low fraction of GNPs can uniformly be dispersed in the matrix and improve the performance of the nanocomposite.

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.

Effect of Graphene Content on Tensile Strength and Microstructure of Aluminum Matrix Composites

In this study, graphene nanoplatelets (GNPs) reinforced aluminum (Al) composites with various GNPs content (0.1, 0.3, 0.5wt.%) were fabricated by powder metallurgy (PM) method. In this method, ultrasonication, mixing, filtering, drying, compacting and sintering processes were performed. The crystal structure and microstructure of powders and fabricated composites were analyzed with X-Ray diffractometer (XRD) and scanning electron microscopy (SEM). With this study, the effects of GNPs content were investigated on the density, Vickers hardness, ultimate tensile strength, and microstructure of Al-GNPs composites. The Vickers hardness (57±2.5 HV) and ultimate tensile strength (120MPa) of Al-0.1%GNPs improved up to +90% and +23.3% when compared with pure aluminum (30±2 HV, 92MPa). From the microstructural analysis, homogeneously distributed GNPs was located at aluminum grain boundaries. The mechanical properties of Al-GNPs composite decreased due to the agglomeration of GNPs above 0.1wt.% GNPs content.

Effect of Graphene Nanoplatelets Content on Dynamic Mechanical Property of GNPs/Ti Composites

In this study, the titanium matrix composites (TiMCs) were fabricated by adding graphene nanoplatelets (GNPs). The dynamic compression test was carried out to study the effect of strain-rate and the GNPs content on dynamic mechanical properties of GNPs/Ti. Results show that the GNPs content (0wt%~0.8wt%) correspond to specific microstructure which affect the dynamic mechanical properties of the composites. Under high strain-rate (3500s-1), the 0.4wt%GNPs/Ti has the highest dynamic stress (~1860MPa) and strain (~30%). The adiabatic shearing band (ASB) microstructure of GNPs/Ti with various GNPs content has been observed under 3500s-1 strain-rate and the ASB microstructure evolution of 0.4wt%GNPs/Ti under different strain rate was investigated in particular.