Epoxy Resin/Graphite Electrically Conductive Nanosheet Nanocomposite

In this study, graphite nanosheets were prepared by powdering expanded graphite with sonication in aqueous alcoholic solution. Epoxy resin/graphite nanosheet nanocomposites were fabricated and their electrical and mechanical properties were investigated. The results revealed that graphite sheets 30-80 nm in thickness could be effectively dispersed within the epoxy resin. The percolation threshold of epoxy resin/graphite nanoparticles was about 0.015, much lower than that of composites with conventional graphite. However, tensile strength, impact strength, and elongation at break of the composites, with increase in graphite nanosheets content, were all sacrificed.     

爆炸法合成石墨烯

以石墨氧化物为前躯体,采用爆炸法合成石墨烯.利用XRD,SEM,XPS,TEM,SAED和Raman等测试手段对石墨烯的形貌,成份和结构进行表征.结果表明,石墨氧化物在爆炸产生的热量和冲击波的作用下发生完全剥离并被还原成石墨烯.新合成的石墨烯呈透明褶皱状,含有2层～5层石墨层,并具有较好的晶体结构.

Abstract：

Graphene nanosheets were synthesized using graphite oxide as a precursor by detonation. The composition,and structure of graphene nanosheets were characterized by X-ray diffraction,X-ray photoelectron spectroscopy,scanning and transmission electron microscopy,selected area electron diffraction,and Raman spectroscopy. Results indicated that the as-prepared material was transparent and wrinkled,and comprised 2-5 graphenes with a highly crystalline structrue. The exfoliation and reduction of graphite oxide to graphene nanosheets was induced by the self-generated thermal energy and shockwave of detonation.     

Production of graphene nanosheets by supercritical CO2 process coupled with micro-jet exfoliation

A facile and cost-effective method which combines supercritical CO₂ and micro-jet exfoliation has been developed for producing graphene nanosheets with high-quality. CO₂ molecules can intercalate into the interlayer of graphite because of their high diffusivity and small molecule size in supercritical operation. The tensile stress induced by graphite interfacial reflection of compressive waves exert on the graphite flakes, which lead to further exfoliation of graphite. Scanning electron microscope (SEM), transmission electron microscope (TEM), atomic force microscopy (AFM), Raman spectrum and X-ray diffraction (XRD) are used to identify morphology and quality of the exfoliated graphene nanosheets, which reveal that the graphite was successfully exfoliated into graphene and more than 88% of graphene nanosheets are less than three layers. The yield of graphene nanosheets is about 28 wt% under optimum conditions, which can be greatly improved by repeated exfoliation of the graphene sediment. The pure graphene film has a high conductivity of 2.1 × 10⁵ S/m.     

超声波频率和作用方式对剥离氧化石墨的影响

化学还原法被认为是实现大规模生产石墨烯的主要途径之一,而剥离氧化石墨为氧化石墨烯是利用该方法获得高品质石墨烯的关键步骤.本文分别利用超声波清洗和超声波粉碎两种方式实现了氧化石墨的剥离,研究了超声波的频率和作用方式对其剥离效率和破坏程度的影响.结果表明,氧化石墨的剥离效率随超声波频率的增大而提高;横向尺寸破坏程度在超声波...     

Surface modified graphite nanosheets used as adsorbent to remove 1,2-dichlorobenzene from water

The surface of graphite nanosheets (GNs) prepared by wet ball milling from expanded graphite (EG) was surface modified during the preparation process. The SEM images shown were employed to analyze the morphology of surface modified graphite nanosheets. The XPS date and Raman spectroscopy show that the milling process gives graphene surface more defects and phenolic groups compared to that of expanded graphite and graphite nanosheets. It was found that after ball milling, the surface modified GNs can be used as an effective adsorbent to remove 1,2-dichlorobenzene from water. Their adsorption capacity reaches 28.3 mg/g, which is comparable to that of carbon nanotubes (CNTs).     

High-quality liquid phase-pulsed laser ablation graphene synthesis by flexible graphite exfoliation

This work reports a one-pot procedure of laser ablation on a graphite target in a liquid medium, based on the variation of different parameters such as target type, laser wavelength, and ablation medium,to obtain high-quality graphene nanosheets. The morphology of derived products was characterized by the field emission scanning electron microscopy(FE-SEM). Then, the morphology and structure of the optimized sample were characterized by transmission electron microscopy(TEM), X-ray diffraction(XRD), ultraviolet-visible-near infrared(UV–vis-NIR) spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy(XPS). By controlling the laser ablation parameters, we were able to prepare micrometer-sized few-layer graphene nanosheets with mainly less than ten layers. Such synthesized graphene nanosheets were grown at the surface of a flexible graphite target, indicating many potential applications in fundamental research, electrochemical and as hydrophobic surfaces.     

Preparation of unsaturated polyester/graphite nanosheet conducting composite under electric field

Unsaturated polyester resin/graphite nanosheet composites were prepared using in situ polymerization under AC electric field which was applied during composite curing to induce orientation of graphite nanosheets. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques have been applied to demonstrate the orientation of graphite nanosheets and results showed that graphite nanosheets were oriented with their flakes parallel to the electric field. As a result, the percolation threshold was decreased to 0.25 wt% due to the orientation of the graphite naosheets.     

超声波和修饰剂及预聚体对石墨层间结构的影响

利用X射线衍射(XRD)、扫描电镜(SEM)和傅立叶红外光谱仪(FT-IR)研究修饰剂、超声波和双马来酰亚胺(BMI)预聚体对纳米石墨薄片的石墨层间结构的影响,结果表明:超声波对膨胀石墨层间距结构的影响,因石墨层间距大小而不同,且超声波并没有破坏膨胀石墨的层状结构;修饰剂和双马来酰亚胺的预聚体可插入纳米石墨薄片中层间距较大的层间,但此层间距的石墨薄片较少,因此插入量也较少,可认为修饰剂或树脂的"插层"主要是插入纳米石墨薄片的网状孔隙内部.     

Aniline- and N,N-dimethylformamide-assisted processing route for graphite nanoplates: intercalation and exfoliation pathway

Aniline-intercalated graphite nanoplates (AGNPs) were synthesized directly from graphite via an intercalation and exfoliation pathway using aniline as the intercalating agent and N,N-dimethylformamide (DMF) as the exfoliating agent. Thus, the obtained AGNPs were dispersible in various organic solvents like ethanol, isopropanol, chloroform, and benzene. This process is convenient, readily scalable and eco-friendly. We found that π-π interactions and the charge transfer complex formation between aniline and graphite nanoplates (GNPs) are responsible for the dispersion of AGNPs in organic solvents. The formation of AGNPs was confirmed by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), X-ray photoelectron (XPS), Raman and UV-Visible spectroscopic measurements.     

Binder derived semi-conductive graphite/alumina composites via novel one-step pulsed electric current sintering

Semi-conductive graphite/Al₂O₃ ceramic composites were successfully fabricated via a novel and facile approach by pulsed electric current sintering of binder embedded Al₂O₃ powders, which were prepared by a simple ball-milling assisted mixing of Al₂O₃ powder with polyvinyl alcohol solution. By altering the sintering conditions with respects to temperature and pressure controlling and concentration of binder, relative density, and microstructure of fabricated graphite/Al₂O₃ ceramic composites, and the electrical properties were schematically investigated in this study. The fabricated graphite/Al₂O₃ ceramic composites exhibit superior semi-conductive properties. Moreover, the carrier type in fabricated semi-conductive graphite/Al₂O₃ composites was successfully modified by adding polycarboxylic acid as a dispersant in binder embedded Al₂O₃ powders. The contents in this work present a new strategy for the design and development of functional ceramic composites.