Papers by Keyword: Expanded Graphite (EG)

Abstract: Expanded graphite (EG) was prepared using fine flake graphite that could go through 50 mesh as raw material, perchloric acid as inserting agent and concentrated nitric acid as oxidant. The effects of amount of raw materials, reaction time and reaction temperature on expanded volume and sorption capacity of EG were studied, and microstructure of EG were characterized by X-ray diffraction patterns and scanning electron microscope. The results show the best process conditions are as follows: m(flake graphite):m(perchloric acid):m(concentrated nitric acid)=1:6:0.18, the reaction time is 50 min and the reaction temperature is 35°C. The reaction condition is moderate and is controlled easily. The sorption capacity of EG will increase almost linearly with increase of expanded volume. The largest expanded volume and sorption capacity of EG are 241 ml/g and 89g/g, respectively, when the expanding temperature is 800°C.

Abstract: A composite photocatalyst of needle ZnO nanorod grafted in the pores of expanded graphite (EG) was prepared by a process of hydrolysis method directly, in which the expanded graphite was prepared by microwave irradiation. Scanning electron microscope (SEM) and Fourier transformation infrared spectroscope (FT-IR) were used to characterize the structure and the chemical structure of the photocatalyst. The results indicate that expanded graphite had a unique net-like pores structure and ZnO Nanorod was loaded on EG to form EG/ZnO composite photocatalyst.

Abstract: We prepared a composite photocatalyst of Stick TiO₂ nanorod loaded on expanded graphite(EG).The growth of TiO₂ in the pores of EG by sol–gel method under normal temperature and pressure was investigated. Results sugest that pores of the EG which can load catalyst particles (TiO₂ nanotube) is the physical base. Stick TiO₂ nanorod can be well loaded on EG to form EG/TiO₂ composite photocatalyst. So a unique process trying to load TiO₂ photocatalyst on EG to EG/TiO₂ composite photocatalyst was developed by us.

Abstract: Expanded graphite (EG) was prepared by microwave irradiation at 1000W for 60s. The growth of coupled ZnO/TiO₂ nanonods in the pores of EG by using hydrolysis method without harsh conditions was investigated and their microstructure was studied by scanning electron microscopy (SEM). Results show that pores of EG, which can load catalytic nanoparticles, is the physical base for growth of catalytic nanorods. The active edges of graphene of freshly EG is a key factor for the growth of coupled ZnO/TiO₂ nanorods under non-catalytic and normal temperature and pressure conditions.

Abstract: In this paper, the adsorption and decolorization capability of expanded graphite (EG) on the simulated wastewater containing Acid Orange Ⅱwere studied. The experimental results show that the initial concentration of wastewater, the dosage of EG, the pH value and the temperature all have greater effects on the decolorization ratio of simulated Acid Orange Ⅱ wastewater. The dye- wastewater containing lower concentration(＜150 mg/L) of Acid Orange Ⅱ is more suitable to be treated by EG, and approximately 100 mg/L is the preferable concentration. The decolorization ratio increases with the increment of the dosage of EG and the temperature level, but the growth rate obviously decreases at the higher initial concentration. All the decolorization ratios under strong acidic (pH<5) and alkalic (pH>11) conditions are higher than that at the range of 5-11 pH values, the highest value even reaches over 94%, while the decolorization ratio under the latter conditions are only between 75% and 85%.

Abstract: Magnetic fluid has many advantages when serving as lubricant. With an appropriate magnetic field this lubricant can prevent leakage and increase the load capacity of lubricant film. It can also be fixed at the friction zone by applying an external magnetic field. This paper aims to improve the lubrication performance of friction pairs under alternating magnetic fields. The test was conducted on a NG-x reciprocating friction tester. Test results using the magnetic fluid and those using expanded graphite were compared. The tribo-surfaces were obtained in real time. It is concluded that the magnetic fluid lubricant has better lubricating property than the nonmagnetic lubricant (expanded graphite) because it can cling on friction pairs uniformly, and the endurance magnetic fluid lubricant is better than that of nonmagnetic lubricant.

Abstract: Polystyrene (PS)/Poly(S-co-MA)/expanded graphite(EG)(PS/PSMA/EG) nanocomposites were prepared by melt blending, using a variety of PSMA/EG.. The electrical and mechanical properties of the PS/PSMA/EG were measured. Mechanical property measurements of composites indicated higher impact strength and lower tensile strength with increasing concentration of PSMA/EG. Exfoliated graphite has seen a significant reduction for composites in electrical resistivity.

Abstract: Graphite nanosheets prepared through high-temperature oxidation via powdering the expanded graphite. After soaking the expanded graphite with styrene(S) and maleic anhydride(MA) monomers, the polymer (Poly(S-co-MA))/expanded graphite(EG) (PSMA/EG) composite granules were obtained by in situ polymerization. Light microscope，scanning electron microscope and X-ray diffraction characterization were performed. SEM analysis indicate that the expanded graphite was mostly tore to sheets with thickness of 50–80 nm and with diameter of 1μm. Optical micrographs showed that the distribution of graphite platelets is found to be nearly uniform.

Abstract: The experiment improved the synthetic methods of preparing expanded graphite, using the mixture of H2SO4 and HNO3 as the acid, KMnO4 as oxidizing agent and adopting chemical oxidization method to prepare the expanded graphite under the conditions of different temperature. We can get the optimum conditions of preparing expanded graphite by orthogonal experiment.

Abstract: Conductive polymer composites (CPCs) consisting of expanded graphite (EG), flake-type graphite (FG) and thermalsetting resin were fabricated by means of a preform molding technique. Conductive fillers, EG and FG, were mechanically mixed with the phenol resin to provide an electrical property to composites. The filler loadings were fixed at 75wt.% to obtain a high electrical conductivity. The mechanical and electrical properties of CPCs were optimized according to the weight ratio and the particle size of FG. As the weight ratio increased, the flexural strength increased, however, the electrical conductivity decreased for both cases of CPCs using different sizes of FG. The particle size was an important parameter to change the mechanical and electrical behaviors. The flexural strength was sensitive to the particle size due to the different level of densification. The electrical conductivity also showed size-dependent behavior because of the different contribution to the conductive networking.