Addition Of Graphene Nanosheets Research Articles

New nano-composite potentiometric sensor composed of graphene nanosheets/thionine/molecular wire for nanomolar detection of silver ion in various real samples

A novel nanographene carbon composite potentiometric sensor for the determination of trace amounts of silver(I) ion was fabricated. Its sensing layer was prepared with the addition of graphene nanosheets into the matrix consisting of graphite powder, diphenylacetylene “a typically molecular wire (MW) as the conductive binder” and thionine as an efficient ionophore. For investigation of the ion-to-electron transducing ability of graphene nanosheets and molecular wire on the electrode surface, the electrochemical impedance spectroscopy measurements were done and the morphology and properties of the electrode surfaces were characterized by scanning electron microscopy. Under the optimized experimental conditions, the suggested potentiometric silver(I) sensor exhibited an excellent Nernstian slope of 59.70mVdecade−1 with a rapid response to silver(I) ion within ~6s. The response was linear in the range 8.00×10−9 to 1.00×10−2molL−1 and calculated detection limit was 4.17×10−9molL−1. The suggested sensor was successfully applied to the determination of silver in radiological film, environmental and drug samples with satisfactory results.

Microstructure and fracture toughness of graphene nanosheets/alumina composites

Graphene nanosheets (GNS)/alumina composites were fabricated by hot pressing. The microstructure and mechanical properties are apparently influenced by the addition of GNS. In particular, the fracture toughness of the composites improves notably. The maximum value is 6.6MPam1/2 for the 0.2wt% GNS/alumina composite, which is about 43.5% higher than that of the monolithic. The main toughening mechanisms are crack deflection, crack bridging, crack branching and the pullout of GNS.

Enhanced mechanical, thermal and flame retardant properties by combining graphene nanosheets and metal hydroxide nanorods for Acrylonitrile–Butadiene–Styrene copolymer composite

Three metal hydroxide nanorods (MHR) with uniform diameters were synthesized, and then combined with graphene nanosheets (GNS) to prepare acrylonitrile–butadiene–styrene (ABS) copolymer composites. An excellent dispersion of exfoliated two-dimensional (2-D) GNS and 1-D MHR in the ABS matrix was achieved. The effects of combined GNS and MHR on the mechanical, thermal and flame retardant properties of the ABS composites were investigated. With the addition of 2wt% GNS and 4wt% Co(OH)2, the tensile strength, bending strength and storage modulus of the ABS composites were increased by 45.1%, 40.5% and 42.3% respectively. The ABS/GNS/Co(OH)2 ternary composite shows the lowest maximum weight loss rate and highest residue yield. Noticeable reduction in the flammability was achieved with the addition of GNS and Co(OH)2, due to the formation of more continuous and compact charred layers that retarded the mass and heat transfer between the flame and the polymer matrix.

Effect of graphene nanosheets on morphology, thermal stability and flame retardancy of epoxy resin

Effect of graphene nanosheets (GNS) on morphology, thermal stability and flame retardancy of epoxy resin (ER) was investigated. GNS was partially exfoliated, large and flat graphene flakes exists in ER/GNS nanocomposites. GNS changed the decomposition pathway of ER at high temperature, enhanced the thermal stability and promoted the formation of char residue. The compactness of both the surface and the bottom char residues were significantly improved with the addition of GNS. Furthermore, GNS can effectively decrease melt flow and inhibit the flammable drips of ER during combustion. Incorporation of 3 wt% of GNS increased the LOI value of ER from 15.7 to 21.0 and reduced the total heat release from 33.37 to 28.20 kJ/m 2 . The peak heat release rate presented earlier increase and later decrease trend with the increase of GNS content due to the competition between the effect of thermal conductivity and barrier property of GNS.

Enhancement of physical properties of electroactive polyimide nanocomposites by addition of graphene nanosheets

Electroactive polyimide (EPI) nanocomposites with amino-capped aniline trimer and 4′-(4,4′-isopropylidene-diphenoxy)bis(phthalic anhydride) as monomers, and functionalized with carboxyl-graphene nanosheets, were prepared by thermal imidization. The as-prepared electroactive polyimide/graphene nanocomposite (EPGN) materials were then characterized by Fourier transform infrared spectroscopy and transmission electron microscopy. In situ monitoring of the redox behavior of the as-prepared EPGN materials was performed by cyclic voltammetry studies. The effects of material composition on the mechanical, thermal, thermal transport, dielectric and molecular barrier properties of EPGN membranes were investigated by dynamic mechanical analysis, TGA, DSC, the transient plane source technique, LCR meter and gas permeability analyzer, respectively. It should be noted that all the properties of the EPGN membranes were found to improve substantially over those of non-electroactive polyimide and EPI. For example, upon loading of 1 wt% graphene, EPGN membranes were found to have an increase of over 20%, 5%, 65% and 20% in mechanical strength, thermal stability, thermal conductivity and dielectric constant, respectively, and a reduction of over 20% in gas permeability. © 2013 Society of Chemical Industry

Preparation of Graphene Nanosheet/Alumina Composites

Graphene nanosheet (GNS)/ Al2O3 composite powder with homogeneously distributed GNSs has been fabricated from wet ball milled expanded graphite and Al2O3, and then followed by the rotary evaporator at relatively low temperature to dry the mixture and the residual solvent was removed in atmosphere-vacuum pipe-type furnace accessing mixed gases of Argon and Hydrogen at 600 for 6h. During the process, homogeneously dispersed and mixed GNS/ Al2O3 composite powders with quite few damage of GNSs structure and properties have been obtained. The microstructures and grain sizes of GNS/ Al2O3 composite powders have been investigated. The results showed that the addition of GNSs had diminished the size of Al2O3 particles and also the as-prepared GNSs/ Al2O3 composite powders can be dispersed and mixed more homogeneously remarkably with the presence of GNSs.

Effect of graphene nanosheets reinforcement on the performance of SnAgCu lead-free solder

Varying weight fractions of graphene nanosheets were successfully incorporated into lead-free solder using the powder metallurgy route. The effects of graphene nanosheets on the physical, thermal, and mechanical properties of a SnAgCu solder alloy were investigated. With the increasing addition of graphene nanosheets, the nanocomposite solders showed a corresponding improvement in their wetting property but an insignificant change in their melting point. The thermomechanical analysis showed that the presence of graphene nanosheets can effectively decrease the coefficient of thermal expansion (CTE) of the nanocomposites. Furthermore, an improvement in UTS and a decrease in ductility were recorded with the addition of graphene nanosheets. The reinforcing mechanism of the graphene nanosheets on various properties obtained was also analyzed in this study.

Preparation and characterization of melt‐blended graphene nanosheets–poly(vinylidene fluoride) nanocomposites with enhanced properties

AbstractNanocomposites of poly(vinylidene fluoride) (PVDF) with chemically reduced graphene nanosheets (GNs) were prepared by melt mixing method and their structure and morphology characterized by SEM analysis. The addition of GNs in the PVDF matrix resulted in changes of the crystallization and melting behaviors. Furthermore, increasing GNs content led to improved thermal stability of the PVDF nanocomposites in air and nitrogen, as well as significant increase in tensile and flexural properties. The nanocomposites' rheological behavior is also affected by the GNs' content. Using oscillatory rheology to monitor the GNs' dispersion, it was found that as the GNs loading increase, the Newtonian behavior disappears at low frequency. This suggests a viscoelastic behavior transition from liquid‐like to solid‐like, with greater GNs content and more homogeneous dispersion resulting in a stronger solid‐like and nonterminal behavior. By using the melt mixing method to disperse GNs, the properties of PVDF are enhanced due to the better dispersion and distribution of GNs throughout the matrix. This improvement could broaden the applications for PVDF nanocomposites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Synthesis and Characterisations of TiO<sub>2</sub> Coated Multiwalled Carbon Nanotubes/Graphene/Polyaniline Nanocomposite for Supercapacitor Applications

Nowadays with ever increasing demand of energy, developing of alternative power sources is an important issue all over the world. In this respect we have prepared nanocomposites based on metal oxide (titanium oxide) coated multiwalled carbon nanotubes (MWCNTs)/polyaniline (PANI) with graphene and without graphene and studied their electrochemical performance. The formation of the polymer in the nanocomposites was confirmed by the Fourier Transform Infrared Spectroscopy (FTIR) study. The morphological characterisations were carried out by the Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM). To characterize the prepared nanocomposites electrode, a cyclic voltammetry test for measuring specific capacitance, and an impedance test were conducted. The highest value of specific capacitance obtained for the TiO2 coated MWCNTs/PANI nanocomposite was 443.57 F/g at 2 mV/s scan rate. Upon addition of graphene nanosheet to the TiO2 coated MWCNTs in a weight ratio of (9:1) the specific capacitance value increased to 666.3 F/g at the same scan rate, also resulting in an increase in energy density and power density.

Effect of graphene nanosheet addition on the electrochemical performance of anode materials for lithium-ion batteries

The structure and electronic properties of graphene nanosheet (GNS) render it a promising conducting agent in a lithium-ion battery. A graphite electrode loaded with GNS exhibits superior electrochemical properties including higher rate performance, increased specific capacity and better cycle performance compared with that obtained by adding the traditional conducting agent–acetylene black. The high-quality sp 2 carbon lattice, quasi-two-dimensional crystal structure and high aspect ratio of GNS provide the basis for a continuous conducting network to counter the decrease in electrode conductivity with increasing number of cycles, and guarantee efficient and fast electronic transport throughout the anode. Effects of GNS loading content on the electrochemical properties of graphite electrode are investigated and results indicate that the amount of conductive additives needed is decreased by using GNS. The kinetics and mechanism of lithium-storage for a GNS-loaded electrode are explored using a series of electrochemical testing techniques.

An investigation on post-fire behavior of hybrid nanocomposites under bending loads

This work focuses on residual bending properties of hybrid nanocomposites after intense heat conditions. Carbon fiber/epoxy-nanoclay and carbon fiber/epoxy-graphene nanosheets were manufactured. The nanoparticles employed were Cloisite 30B nanoclay and surface modified graphene nanosheets. The epoxy system was RemLam M/HY956. For short beam samples exposed to 800 KW/m 2 heat flux, for a various period of time up to 120 s, the addition of nanoparticles (nanoclay and graphene nanosheets) increased the unburned thickness from 0.16 mm (original) to 2.63 mm and 2.74 mm, respectively. When the two-dimensional (plates) samples were tested, the improvement on heat performance was reduced. The unburned thickness improved close to 10% with the presence of nanoclay. The addition of graphene nanosheets leads to a decrease in unburned thickness of 12.8%. This result can be due to the good thermal protection properties of the graphene nanosheets. Using SEM analysis, it was observed that when the hybrid nanocomposites were subjected to a large heat flux, nanoparticles remained trapped inside the char layers. Finally, the proposed model seems to overestimate the residual bending response by 8%.