جستجوی مقالات مرتبط با کلیدواژه « nanocomposite » در نشریات گروه « مواد و متالورژی »

Nowadays, energy storage has become a crucial challenge for humanity. Supercapacitors have emerged as a promising option for energy storage due to their numerous advantages. In this study, Co3O4/RGO nanocomposite electrode materials with high specific capacity and favorable electrochemical performance and cycling stability for electrochemical applications were synthesized via a one-step hydrothermal method on a nickel foam substrate and compared with cobalt oxide nanoparticles. The synthesized samples were characterized using various techniques, including X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and Fourier-transform infrared spectroscopy. For electrochemical evaluation, the synthesized nanostructures were examined in a three-electrode system with a 6 M KOH electrolyte. Cyclic voltammetry and galvanostatic charge-discharge tests were performed. The obtained specific capacity for the hybrid sample was 634.8 F/g at a current density of 1.5 A/g. In contrast, the specific capacity for the cobalt oxide nanoparticle sample was obtained to be 206.1 F/g, indicating a significant capacity enhancement for the hybrid sample. The demonstrated favorable electrochemical performance could be attributed to the nanoscale morphology and hybrid composition.

Water pollution is one of the recent problems of societies. In recent years, there has been a lot of focus on finding new ways to purify water. In addition, the usual and old purification methods cannot effectively remove new chemical pollutants from water. Therefore, these pollutants inflict lots of problems including different diseases. Thus, new methods and materials that can effectively remove these chemicals from water are important. New absorbents have been one of the hot topics for researchers in recent years. In this research, alumina particles were coated with zinc oxide via hydrothermal method. The produced nanocomposites were utilized to remove organic pollutants from water. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and Zeta potential were used to characterize the nanocomposites. X-ray diffraction results showed that an alumina-zinc oxide nanocomposite was well formed. The formation reactions of nanostructured zinc oxide on the alumina were also discussed. Microstructural studies showed that the size of zinc oxide particles was about 45 nm and zinc oxide particles were composed of nano-size layers. The adsorption results exhibited that the dye removal efficiency of the nanocomposite was significantly increased compared to the pure single-phase alumina. 98% of the methyl orange was removed by the nanocomposite sample within 15 minutes.

In this study, the effect of the perlite nanoparticles on the mechanical properties of a pearlite/NR/HDPE nanocomposite was experimentally investigated. A high-density polyethylene/natural rubber /perlite nanocomposite was synthesized using an internal mixer and a melt mixing method, with varying compositions. Uniaxial tension tests were carried out to obtian the tensile strength and elongation of the samples. The response surface method and the central composite design were employed as experiment design and optimiztion tools to obtian the influence of composite composition parameters, specifically, the weight percentage of perlite and natural rubber. Furthermore, scanning electron microscopy was utilized to inspect the microstructure of the nanocomposite samples, and to evaluate the efficacy of the mixing method. The experimental results derived from the various samples revealed that a sample containing 7 wt.% perlite nanoparticles and 20 wt.% natural rubber demonstrated a significant enhancement in the tensile strength, reaching up to 12 MPa. Moreover, the multivariable optimization data suggested that the optimal weight percentages for natural rubber and perlite nanoparticles were 36.89% and 3.00%, respectively. Under these conditions, both the tensile strength and the elongation at failure point achieved their maximum values, recorded as 8.32 MPa and 38.89%, respectively.

In this study, wollastonite nanoparticles were synthesized and calcined at different temperatures. The resulting particles were added to a polymeric gelatin containing drug, and the gelatin/wollastonite nanocomposite was prepared as a carrier for gentamicin drug. The structure and morphology of the prepared particles and composites were evaluated using X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR) Spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), and Transmission Electron Microscopy (TEM). The results showed the synthesis of single-phase wollastonite nanoparticles with sizes less than 10 nanometers, which agglomerate in some regions. The drug delivery rate in phosphate buffer solution, as analyzed by UV analysis at λmax=201 nm, indicated rapid degradation of the composite, with about 60% of the drug delivered in the initial hours and complete delivery after 2 days. Therefore, it can be concluded that the resulting composite is biodegradable and has the potential to be used as filler for bone defects and local drug delivery.a

Surface modification with biomolecules can overcome Graphene Oxide (GO) restrictions in biocompatibility, cellular internalization, and drug delivery effectiveness, hence  suitable for a wide range of biomedical applications. In this study, a biocomposite (L-glutamine-functionalized magnetic graphene oxide (L-Gln/MGO)) was prepared and used as a suitable nanoscale carrier with high drug loading capacity and excellent release properties for 5-fuorouracil (5FU), an anticancer drug. The optimum pH for maximum drug adsorption was determined as 4 at 293 K and as the temperature increased, the adsorption capacity decreased due to the exothermic nature of the adsorption process. Some well-known models, including pseudo-first-order, pseudo-second-order, and Intraparticular Diffusion (IPD), were applied to examine the kinetics of adsorption. Additionally, the Langmuir, Freundlich, and Redlich-Peterson models were used to investigate the adsorption isotherms. The obtained results showed that the adsorption process adhered to the Langmuir isotherm and pseudo-second-order kinetic models. Nearly 26% of 5FU was released in the simulated stomach fluid at the pH of 1.2 and temperature of 37 °C in the first 30 minutes while 32% of which was released in the simulated intestinal fluid at the pH of 7.4 during the next 30 hours. The obtained results might be helpful for designing a controllable loading and targeted 5FU drug delivery system.

In this research, α-MnO2 nanorod was synthesized by a novel morphology controlled hydrothermal method in the absence of mold for electrochemical energy storage. Graphite oxide (GO) was synthesized using the modified Hummers method. The oxygenated groups of GO were eliminated by the use of hydrazine to produce the reduced graphene oxide (RGO). Nanocomposites with different percentages were made with reduced graphene oxide (G) and manganese dioxide (M) (G20M80, G40M60, G80M20) and were characterized successfully with appropriate methods. To investigate the electrochemical capacitor behavior of various samples, cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) experiments were performed in a three-electrode system containing 0.5 M Na2SO4 solution as the electrolyte. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) study in 10 mM K4Fe(CN)6 containing 0.1 M KCl also investigated to evaluate the surface properties of the electrodes. The results of the electrochemical experiments showed that the G40M60 electrode had the lowest resistance to charge transfer and ionic diffiution. The results of electrochemical tests revealed excellent supercapacitor behavior of G40M60 nanocomposite and high stability of 91% after 50 charge-discharge cycles at 5 Ag-1 current density. The specific capacitance for the G40M60 nanocomposite was higher than that of other samples and was calculated as 179.72 F.g-1 in current density of 0.6 A.g-1.

Dealing with the destructive effects of electromagnetic waves requires materials with the ability to lose magnetic and electrical energies. These materials are mainly composed of a magnetic material and an electrically conductive material. In the present research, at first, strontium ferrite nanoparticles doped with manganese and calcium with the formula of SrCo2-X(Mn Ca)X/2Fe16O27 (x=0.0-0.5) were synthesized by co-precipitation method. Then these nanoparticles were composited together with functionalized carbon nanotubes (with a volume ratio of 1 to 5%). X-ray diffraction analysis, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, vibrating sample magnetometer, and vector network analyzer were used to investigate the structural, magnetic, and microwave properties of the samples. The X-ray diffraction pattern results showed that the strontium ferrite phase was formed in all compounds, and there was no evidence of any impurities in the samples. FE-SEM results indicated that the particles completely covered the outer walls of the carbon nanotubes. Magnetometer test results also showed that with an increase in the amount of manganese and calcium cations in strontium ferrite, the saturation magnetization decreased and the coercive force increased. Reflection losses were also at least 30% higher in composite samples than those of in ferrite samples. The highest reflection loss (7.42 dB at a frequency of 1.12 GHz) was observed in the nanocomposite sample containing 5% by volume of carbon nanotubes. However, based on the results, the sample containing 4% by volume of carbon nanotubes had a wider absorption bandwidth compared to other samples.

Conductive polymer matrix nanocomposites are suitable choice as a conductive material. in conductive polymer composites with segregated structure, percolation threshold is lower than random composites by the reason of particles location. In these composites particles are only located at polymers matrix particles interface instead of being distributed randomly throughout the system. in this study, a HDPE/CNT nanocomposites with segregated structure were fabricated by dry mixing method in order to achieve significant conductivity in low weight conductive phase percentages. due to Improve mechanical properties, the second polymer phase, which has a lower molecular weight than first polymer, was added to composites structure. SEM images confirms the presence of CNTs at polymer granules boundaries. The conductivity in one weight percent of CNT phase for composite without second polymer phase was reported as 1.0491 S/m and in composite with second polymer phase was 0.4518 S/m. Tensile test results also show improved mechanical properties in L-2CNT composite compared to H-2CNT.

Considering the structural applications of polymer composites and the increasing demand for greater strength and stiffness of these types of composites, also due to the unique properties of Carbon Nano Tubes (CNTs), the possibility of using Carbon nanotubes as an additional reinforcement in a polymer composite have been investigated. In this research, the representative volume element (RVE) is studied in different percentages and sizes of Carbon nanotubes. First, the analytical equations for predicting the elastic behavior of a representative volume element are presented, then the mechanical behavior of element is investigated by modeling the element in ABAQUS finite element software. The main objective of this research is to model and extract the elastic mechanical properties of polymer nanocomposite with epoxy resin underlay with carbon and glass fiber as the first reinforcement and carbon nanotube as the second reinforcement. Axial and bending loading is applied to the element as a displacement and single rotation. The results show that the axial and flexural stiffness of glass fiber-reinforced composite with 5 percent carbon nanotubes (inner radius=2nm) increase by 83.8% and 244.9%, respectively, while those for carbon fiber-reinforced composite and with the same conditions, it is 17.5% and 54.9%, respectively. On the other hand, increasing the thickness of carbon nanotubes by 1.5 nm causes a significant increase in the axial and flexural strength values of the composite reinforced with glass and carbon fibers.

In this research, the tensile properties of polypropylene/natural rubber composite reinforced with perlite nanoparticles were studied. The mathematical modeling of analysis of variance using the surface response method was used to confirm the experimental results. The role of each materials variable and the weight percentage of natural rubber and pearlite nanoparticles on the tensile properties of the nanocomposite samples was investigated. It was observed that the values of tensile strength and elongation at break by increasing the amount of natural rubber from 20 wt.% to 40 wt.% and the constant amount of perlite nanoparticles at 3 wt.%, decreased by 14.68% (from 8.92 to 7.61 MPa) and increased by 72% (from 51.05% to 87.81%), respectively. The results obtained from the parameters optimization showed that the maximum values of tensile strength and elongation at break are 8.332 MPa and 74.38% was obtained in the sample with 3.268 wt.% of natural rubber and 4.046 wt.% of perlite nanoparticles, respectively. The scanning electron microscope images showed the positive effect of adding nanoparticles to the polypropylene/natural rubber composite due to the reduction in the size of the elastomeric phase and as a result, the increase in the tensile strength of the composite samples. Also, the proper dispersion of nanoparticles in the polymer matrix phase occurred in the sample with 5 wt.% of perlite nanoparticles and 30 wt.% of natural rubber. However, with increasing the weight percentages of nanoparticles up to 9 wt.%, some agglomerations of pearlite nanoparticles were observed in the thermoplastic phase.

The purpose of this research is synthesis of nanocomposite with high photocatalyst property and magnetic separation ability in order to degradation of organic pollutants and reusability, respectively. Therefore, Eu doped ZnS - Fe3O4 nanocomposite is synthesized via sonochemical method which this method is easy and low cost. The synthesized photocatalyst is investigated with X-ray Diffraction Pattern (XRD), Energy Dispersive X-ray Spectroscopy (EDS), Photoluminescence Spectroscopy (PL), UV-Vis Spectrophotometry. As a consequence of testing the capability of magnetic separation, the high amount of photocatalyst attracted by the magnet guarantees the property of recyclability. Photocatalytic application in presence of synthesized nanocomposite for degradation of Rhodamine-B dye under UV-C and visible lamp is studied and results showed 81% and 78% degradation efficiency under UV-C lamp for 3 hours and visible lamp for 1 hour, respectively. In addition, stability and reuse investigation showed that the nanocomposite still remains its photocatalytic capacity after 3 cycles test.

In this research, Ni-Co/Gr nanocomposite coating was applied on a low carbon steel substrate based on electrodeposition method under pulse-reverse current using watt plating solution in the presence of saccharin with 0.05 g/L graphene. For better graphene distribution, the plating solution was sonicated. The microstructure of the coating was examined by scanning electron microscopy, atomic force microscopy, and X-ray diffraction, and its corrosion resistance was assessed by polarization and Electrochemical Impedance Spectroscopy (EIS) analysis. The results showed that the coating included Ni-Co/Gr alloy with a smooth surface morphology and contained about 26 % by weight of cobalt. Graphene reinforcing particles were co-deposited on the surface. The average grain size of the Ni-Co/graphene composite coating was obtained as about 7 nm, indicating the formation of a very fine-grained structure. The hardness value of the sample increased from 220 HV (microhardness of the substrate) up to 496 HV followed by nanocomposite coating application. The results of the corrosion tests showed that the corrosion resistance of the coated sample was much higher than that of the uncoated steel. As a result of applying this coating, the corrosion rate decreased from 0.611 mm/y to 0.0029 mm/y.

The present research has studied the effect of adding perlite and natural rubber nanoparticles with various weight percentages on the tensile modulus and impact strength of polypropylene. For this purpose, different samples were produced and tested using an internal mixer based on the standards of tensile and impact tests. Also, by using of response surface methodology (RSM), the role of input parameters on the responses was investigated in order to achieve optimal mechanical properties and predict these properties with mathematical models in the form of central composite five-level design (CCD). In addition, the SEM test was used to observe the changes made in the microstructure of the samples. The results showed that the addition of 7 wt.% of pearlite nanoparticles to the matrix containing 20 wt.% of natural rubber, the value of the tensile modulus increased by 11.27% and the impact strength by 52.01% compared to the addition of 3 wt.% of pearlite nanoparticles to the same matrix. The results of multiobjective optimization proved that the optimal weight percentage of pearlite nanoparticles and natural rubber was 4.04 and 35.26% wt. respectively. Is. In this case, the highest value obtained for tensile modulus was 508.04 MPa and impact strength was determined to be 108.52 J/m. By observing the SEM images, it was concluded that the change in the size of the elastomeric phase due to the use of different weight percentages of reinforcements has caused the results of the mechanical properties of the samples to differ from each other.