Relevant bibliographies by topics / Graphene dispersion

Academic literature on the topic 'Graphene dispersion'

Author: Grafiati
Published: 10 December 2022
Last updated: 28 January 2023

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Journal articles on the topic "Graphene dispersion"

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Wu, Li Li, Xiang Lv, and Chao Can Zhang. "Preparation and Dispersion of Polyacrylamide-Grafting Graphene." Advanced Materials Research 306-307 (August 2011): 1360–63. http://dx.doi.org/10.4028/www.scientific.net/amr.306-307.1360.

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Graphene has weak interface compatibility to its solvent, and it is easy to get agglomeration in the solvent. In this paper, graphehe is modified by grafting method to improve the aqueous dispersion. Oxidized graphene is firstly prepared by modified Hummer’s method and supersonic exfoliation. Then oxidized graphene is grafted by hydrophilic polymer polyacrylamide (PAM) and deoxidized into modified graphene. The product is characterized by TEM, FTIR, Raman spectroscopy and sedimentation test. And the result demonstrates a modified graphene is successfully synthesized and its compatibility to the media is enhanced as assumption. When the ratio between PAM and graphene is 1:10, the suspension absorbance is improved as twice as common graphene’s. Meanwhile the concentration of graphene in suspension can reach 0.05mg/ml without any agglomeration.
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Касцова, А. Г., Н. В. Глебова, А. А. Нечитайлов, А. О. Краснова, А. О. Пелагейкина, and И. А. Елисеев. "Электронная спектроскопия графена, полученного методом ультразвукового диспергирования." Письма в журнал технической физики 48, no. 24 (2022): 23. http://dx.doi.org/10.21883/pjtf.2022.24.54019.19268.

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Technology of obtaining graphene by means of ultrasonic dispersion of thermally expanded graphite in the presence of a surface-active polymer Nafion is presented. The technology makes it possible to obtain large amounts of low-layer (1-3 layers) graphene in a relatively short time. An approach to control the dispersion process based on UV spectroscopy of dispersions is described. A mechanism is proposed for the effect of a surface-active polymer on the production of low-layer graphene by ultrasonic dispersion.
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Perumal, Suguna, Raji Atchudan, and In Woo Cheong. "Recent Studies on Dispersion of Graphene–Polymer Composites." Polymers 13, no. 14 (July 20, 2021): 2375. http://dx.doi.org/10.3390/polym13142375.

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Graphene is an excellent 2D material that has extraordinary properties such as high surface area, electron mobility, conductivity, and high light transmission. Polymer composites are used in many applications in place of polymers. In recent years, the development of stable graphene dispersions with high graphene concentrations has attracted great attention due to their applications in energy, bio-fields, and so forth. Thus, this review essentially discusses the preparation of stable graphene–polymer composites/dispersions. Discussion on existing methods of preparing graphene is included with their merits and demerits. Among existing methods, mechanical exfoliation is widely used for the preparation of stable graphene dispersion, the theoretical background of this method is discussed briefly. Solvents, surfactants, and polymers that are used for dispersing graphene and the factors to be considered while preparing stable graphene dispersions are discussed in detail. Further, the direct applications of stable graphene dispersions are discussed briefly. Finally, a summary and prospects for the development of stable graphene dispersions are proposed.
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Li, Liangchuan, Ming Zhou, Long Jin, Youtang Mo, Enyong Xu, Huajin Chen, Lincong Liu, Mingyue Wang, Xin Chen, and Hongwei Zhu. "Green Preparation of Aqueous Graphene Dispersion and Study on Its Dispersion Stability." Materials 13, no. 18 (September 14, 2020): 4069. http://dx.doi.org/10.3390/ma13184069.

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The large-scale preparation of stable graphene aqueous dispersion has been a challenge in the theoretical research and industrial applications of graphene. This study determined the suitable exfoliation agent for overcoming the van der Waals force between the layers of expanded graphite sheets using the liquid-phase exfoliation method on the basis of surface energy theory to prepare a single layer of graphene. To evenly and stably disperse graphene in pure water, the dispersants were selected based on Hansen solubility parameters, namely, hydrophilicity, heterocyclic structure and easy combinative features. The graphene exfoliation grade and the dispersion stability, number of layers and defect density in the dispersion were analysed under Tyndall phenomenon using volume sedimentation method, zeta potential analysis, scanning electron microscopy, Raman spectroscopy and atomic force microscopy characterization. Subsequently, the long-chain quaternary ammonium salt cationic surfactant octadecyltrimethylammonium chloride (0.3 wt.%) was electrolyzed in pure water to form ammonium ions, which promoted hydrogen bonding in the remaining oxygen-containing groups on the surface of the stripped graphene. Forming the electrostatic steric hindrance effect to achieve the stable dispersion of graphene in water can exfoliate a minimum of eight layers of graphene nanosheets; the average number of layers was less than 14. The 0.1 wt.% (sodium dodecylbenzene sulfonate: melamine = 1:1) mixed system forms π–π interaction and hydrogen bonding with graphene in pure water, which allow the stable dispersion of graphene for 22 days without sedimentation. The findings can be beneficial for the large-scale preparation of waterborne graphene in industrial applications.
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Takeda, Shimpei, and Yuta Nishina. "Structural Optimization of Alkylbenzenes as Graphene Dispersants." Processes 8, no. 2 (February 19, 2020): 238. http://dx.doi.org/10.3390/pr8020238.

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Among the several methods of producing graphene, the liquid-phase exfoliation of graphite is attractive because of a simple and easy procedure, being expected for mass production. The dispersibility of graphene can be improved by adding a dispersant molecule that interacts with graphene, but the appropriate molecular design has not been proposed. In this study, we focused on aromatic compounds with alkyl chains as dispersing agents. We synthesized a series of alkyl aromatic compounds and evaluated their performance as a dispersant for graphene. The results suggest that the alkyl chain length and solubility in the solvent play a vital role in graphene dispersion.
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Azmi, Amirul Hadi, Shaharin Fadzli Abd Rahman, and Mastura Shafinaz Zainal Abidin. "Microcrystalline Cellulose as Graphite Exfoliation Agent and its Effect on Electrical Conductivity." Solid State Phenomena 317 (May 2021): 144–51. http://dx.doi.org/10.4028/www.scientific.net/ssp.317.144.

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Graphene has drawn a lot of attention as a promising material for a conductive ink due to its high electrical conductivity and abundant source. Selection of solvent for ink formulation is crucial to obtain the desired result. In this work, microcrystal cellulose solution is investigated as alternative solvent for conductive ink formulation. Although the viability of the microcrystal cellulose solution was already presented in other works, further thorough and systematic study is highly required. Cellulose solution was prepared using microcrystalline cellulose and sodium hydroxide aqueous solution. Dispersions with different graphite-to-cellulose ratio were prepared. The exfoliation process was for sonication times of 8, 16, 24 and 32 hours. For Raman spectroscopy and 4-point probe measurement, graphene thin film was formed by drop-casting 20μl dispersion on glossy paper. Sample with low graphite-to-cellulose ratio exhibited more significant reduction in unexfoliated graphite content over the sonication time. The sufficient amount of cellulose in the dispersion leads to more effective exfoliation process. According to analysis on the Raman spectra, the exfoliated graphite could be classified as few-layer graphene with low defect content. The drop-casted thin film from dispersion with ratio of 20:1 showed sheet resistance lesser than 100 Ω/sq. The obtained results confirmed the effectiveness of microcrystal cellulose as the agent for exfoliation process.
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Liu, Hong Bo, Wu Ying Zhang, Feng Lin, and Hong Da Cao. "Comparison and Characterization of Two Preparation Methods of Graphene Oxide." Advanced Materials Research 989-994 (July 2014): 125–29. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.125.

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The graphene oxides were prepared form graphite by thermal expansion and ultrasonic dispersion. The structure of graphene oxides was characterized by Fourier transform infrared spectrometer (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD) and Raman spectra. The difference of structure of graphene oxides by two preparation methods was compared. The measurement of FTIR and XRD showed the graphite was completely oxidized. The graphene oxide prepared by thermal expansion would lose large number of active functional groups, such as hydroxyl, carboxyl group, et al. However, the graphene oxide prepared by ultrasonic dispersion can retain these active functional groups. These active functional groups will be benefit to chemically modify the graphene oxides and prepare the polymer/graphene nanocomposites.
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Hung, Wei-Song, Tzu-Jen Lin, Yu-Hsuan Chiao, Arijit Sengupta, Yi-Chen Hsiao, S. Ranil Wickramasinghe, Chien-Chieh Hu, Kueir-Rarn Lee, and Juin-Yih Lai. "Graphene-induced tuning of the d-spacing of graphene oxide composite nanofiltration membranes for frictionless capillary action-induced enhancement of water permeability." Journal of Materials Chemistry A 6, no. 40 (2018): 19445–54. http://dx.doi.org/10.1039/c8ta08155g.

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Zhao, Hai Chao, Yu Lin Qiao, and Yan Zang. "Research on Graphene Preparation by Liquid Phase Ultrasonic Exfoliation and Antifriction Performance in Water." Key Engineering Materials 609-610 (April 2014): 218–24. http://dx.doi.org/10.4028/www.scientific.net/kem.609-610.218.

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The different layers of graphene were prepared by liquid ultrasonic direct exfoliation. The dispersion stability of graphene in water under different ultrasonic time, the antifriction Performance, and the elements and morphology of the wear surface are investigated. The wear mechanism of graphene solution was preliminarily discussed. The results indicate that graphene with thickness of 10nm-150nm can be produced by ultrasonic peeling expanded graphite and the dispersion stability of graphene aqueous is best when sonicating for 3h. The antifriction property and wear mechanism of graphene aqueous vary with the graphene content. When graphene content is 0.01wt%, the antifriction performance of graphene aqueous was optimum and its wear mechanism was abrasive wear.
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Liu, Hong Bo, Wu Ying Zhang, and Feng Lin. "Synthesis and Property of Polyurethane Acrylates Modified Graphene Oxide." Key Engineering Materials 703 (August 2016): 273–77. http://dx.doi.org/10.4028/www.scientific.net/kem.703.273.

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The graphene oxides were synthesized form graphite by ultrasonic dispersion in water, N-methylpyrrolidone (NMP), N,N-dimethyl-formamide (DMF), acetone and dimethylbenzene, and the polyurethane acrylates containing the reactive NCO (PACN) were prepared. Then the polyurethane acrylates modified graphene oxide synthesized by ultrasonic dispersion in N-methylpyrrolidone (NMP), N,N-dimethyl-formamide (DMF), acetone were prepared by NCO of PACN reacting with the hydroxyl groups of the graphene oxides. The polyurethane acrylates modified graphene oxide was characterized by Fourier transform infrared spectrometer (FTIR), scanning electron microscope (SEM) and Raman spectra. The FTIR spectra showed that the NCO of PACN reacted with the hydroxyl groups of graphene oxide synthesized by ultrasonic dispersion. The measurement of SEM and Raman spectra showed that the polyurethane acrylates modification didn't change the structure and surface morphology of graphene oxide.
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Dissertations / Theses on the topic "Graphene dispersion"

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Wei, Jiacheng. "Graphene in epoxy system : dispersion, preparation and reinforcement effect." Thesis, Northumbria University, 2017. http://nrl.northumbria.ac.uk/36264/.

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Epoxy is one of the most adaptable and widely sold high performance material in the world because of its excellent mechanical properties, thermal stability, chemical and corrosion resistance, low shrinkage, low cost, and ease of processing, etc. Graphene shows good potential for the fabrication of high performance polymer nanocomposites because of its unique planar structure and its superlative mechanical properties, thermal conductivity and excellent electrical conductivity. The layered structure allows a large surface contact area with the matrix and thus leads to improvements in the properties. This work aims at exploiting the potential use of graphene as a filler to reinforce epoxy matrix and the preparation of homogeneously dispersed epoxy/graphene nanocomposites. To explore the maximum property enhancement of graphene in epoxy, dispersion is the key factor. However, in the preparation of epoxy/graphene nanocomposites, there still exist some challenges. One of the largest obstacles it that graphene tends to reagglomerate in liquid epoxy, which is due to the strong van der Waals force on the graphene surface. If not properly dispersed, the agglomerated graphene will act as a defect within the matrix and consequently lower the properties of the nanocomposites. Therefore, the dispersion of graphene and the processing techniques should be studied. In this work, epoxy/graphene nanocomposites had been made by different processing techniques. Different characterization methods had been applied to evaluate the reinforcement effect. By end of this work, graphene dispersion techniques and sample preparation methods have been optimized. Epoxy/graphene nanocomposites have been prepared with enhanced properties.
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O'Driscoll, Luke James. "New responsive surfactants for aqueous dispersion of CNTs and graphene." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10647/.

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We have developed a flexible approach to the synthesis of surfactants with an ‘Anchor Linker-Head’ (ALH) architecture. These ALH surfactants are designed for the dispersion of multi-walled carbon nanotubes (MWNTs) and exfoliation of graphite in water. Four series of surfactants have been synthesised, all with a pyrene anchor group, which binds strongly to graphitic surfaces through π-π interactions, and hydrophilic head groups based on a carboxylate moiety, carboxylate dendron, crown ether or podand. These are joined by oligoethylene glycol (OEG) linker groups. The anionic surfactants PyrB-PEGn-CH2COONa (n = 2, 4, 6, 12) PyrB-PEGn-CH2COG1(ONa)3 (n = 2, 4, 6) all disperse MWNTs at least as well as commercial surfactants in Millipore water and achieve higher dispersion levels than comparable amide linker surfactants. Non-ionic surfactants are more effective, dispersing up to 61% of the MWNT feedstock. Exfoliation of graphite has been achieved using anionic and non-ionic surfactants. We examined the effect of salts, including NaCl, KCl and CaCl2, on the ability of surfactants to disperse MWNTs and found the choice of linker and head group to be significant. MWNT dispersing ability in 0.6 M NaCl increases with OEG linker length. Structural variation gives surfactants which show improved, reduced, or comparable dispersion levels in 0.6 M NaCl vs. Millipore water, due to the effects of ionic screening and cation coordination. MWNTs dispersed using anionic surfactants can be precipitated by addition of acid, and re-dispersed by addition of base. Eleven non-ionic surfactants have a lower critical solution temperature (LCST), which is tuned by structural changes. We demonstrate using PyrB-PEG4-CH2CO(15-c-5) that LCST surfactants with a pyrene anchor can be used to repeatedly and reversibly precipitate dispersed MWNTs without harsh re-processing. We believe this to be the first report of such behaviour using a small molecule dispersant.
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Rodgers, Andrew Norman John. "Dispersion, assembly and electrochemistry of graphene at the liquid-liquid interface." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/dispersion-assembly-and-electrochemistry-of-graphene-at-the-liquidliquid-interface(c2ffd27a-cf5f-45c2-a471-60dcab788e12).html.

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The dispersion of graphene in 1,2-dichloroethane (DCE), its subsequent attachment at the water-DCE interface and the reduction of oxygen at the water-DCE interface proceeding via interfacial graphene have been investigated. Using addition of an electrolyte which screens surface charge, it was found that electrostatic repulsions play a significant role in determining the kinetic stability of lyophobic non-aqueous graphene dispersions. The onset of aggregation was determined and it was found that dispersions prepared from higher-oxygen content graphite were more stable than those prepared from lower-oxygen content graphite, indicating that oxygen content is important in determining the surface charge on graphene in non-aqueous dispersion. The presence of organic electrolyte was also found to promote assembly of graphene into a coherent film at the liquid-liquid interface. Measurement of the liquid-liquid interfacial tension and three-phase contact angle revealed that the energetics of particle attachment did not change in the presence of organic electrolyte, thus indicating a mechanism of inter-particle electrostatic repulsion minimisation through surface charge screening. Interfacial graphene was found to display a catalytic effect toward the oxygen reduction reaction at the water-DCE interface. A bipolar cell was developed which showed that this reaction occurs heterogeneously, with graphene acting as a conduit for electrons across the water-DCE interface.
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Phan, Anh Duc. "Graphene Casimir Interactions and Some Possible Applications." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4386.

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Scientific development requires profound understandings of micromechanical and nanomechanical systems (MEMS/NEMS) due to their applications not only in the technological world, but also for scientific understanding. At the micro- or nano-scale, when two objects are brought close together, the existence of stiction or adhesion is inevitable and plays an important role in the behavior operation of these systems. Such effects are due to surface dispersion forces, such as the van der Waals or Casimir interactions. The scientific understanding of these forces is particularly important for low-dimensional materials. In addition, the discovery of materials, such as graphitic systems has provided opportunities for new classes of devices and challenging fundermental problems. Therefore, invesigations of the van der Waals or Caismir forces in graphene-based systems, in particular, and the solution generating non-touching systems are needed. In this study, the Casimir force involving 2D graphene is investigated under various conditions. The Casimir interaction is usually studied in the framework of the Lifshitz theory. According to this theory, it is essential to know the frequency-dependent reflection coefficients of materials. Here, it is found that the graphene reflection coefficients strongly depend on the optical conductivity of graphene, which is described by the Kubo formalism. When objects are placed in vacuum, the Casimir force is attractive and leads to adhesion on the surface. We find that the Casimir repulsion can be obtained by replacing vacuum with a suitable liquid. Our studies show that bromobenzene is the liquid providing this effect. We also find that this long-range force is temperature dependent and graphene/bromobenzene/metal substrate configuration can be used to demonstrate merely thermal Casimir interaction at room temperature and micrometer distances. These findings would provide good guidance and predictions for practical studies.
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Peixoto, Renato de Oliveira. "Estudo de propriedades vibracionais em sistema de baixa dimensionalidade /." Rio Claro, 2019. http://hdl.handle.net/11449/182253.

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Orientador: Ricardo Paupitz Barbosa dos Santos
Resumo: Neste trabalho, tivemos como objetivo obter a dispersão de fônons de materiais bidimensionais, por meio de simulações de dinâmica molecular clássica, a fim de examinar propriedades mecânicas e elásticas, como a velocidade do som, módulo volumétrico, módulo de cisalhamento, coeficiente de Poisson e módulo de Young. Apresentamos as principais características da ferramenta utilizada na investigação, o método de dinâmica molecular clássica. Abordamos o Algoritmo Velocity Verlet, empregado para a integração das equações de movimento; o Ensemble estatístico, utilizado para realizar as simulações; o termostato de Nosé-Hoover, responsável por regular a temperatura do sistema; e os potenciais que descrevem as interações atômicas. Utilizamos potenciais reativos, sendo eles Tersoff, Tersoff-2010, AIREBO e ReaxFF. As simulações computacionais foram realizadas através do software LAMMPS. Além disso, discorreremos sobre a dinâmica de rede, a obtenção das curvas de dispersão a partir da construção da matriz dinâmica, por meio da matriz dos coeficientes de rigidez baseado nos deslocamentos dos átomos. Os materiais de baixa dimensionalidade investigados nesta dissertação são derivados do carbono como o grafeno, grafeno bifenileno – BPC e nanotubos. As propriedades vibracionais e elásticas calculadas, para o grafeno foram comparadas com resultados experimentais para o grafite no plano e resultados de simulações de dinâmica molecular. O grafeno bifenileno e os nanotubos de carbono foram compara... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: In this work, we aimed to obtain the phonon dispersion of two-dimensional materials by classical molecular dynamics simulations, in order to explore mechanical and elastical properties, such as velocity of sound, volumetric modulus, shear modulus, Poisson's ratio, and Young's modulus. We present the main features of the tool used in the research, the classical molecular dynamics method. We approach the Velocity Verlet Algorithm, used for the integration of the equations of motion; the statistical Ensemble, used to perform the simulations; Nosé-Hoover’s thermostat, responsible for regulate the system temperature; and the potentials that describe the atomic interactions. We used reactive potentials, being Tersoff, Tersoff-2010, AIREBO and ReaxFF. The computational simulations were performed through LAMMPS software. In addition, we will discuss lattice dynamics, the obtaining the dispersion curves from the dynamic matrix construction, through the matrix of stiffness coefficients based on the displacements of the atoms. The low-dimensional materials investigated in this dissertation are derived from carbon such as graphene, graphene biphenylene - BPC and nanotubes. The calculated vibrational and elastical properties for graphene were compared with experimental results for graphite in-plane and results of molecular dynamics simulations. Graphene biphenylene and carbon nanotubes were compared with graphene values. The other materials, biphenylene nanotubes, were compared with carbo... (Complete abstract click electronic access below)
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Lagier, Laura. "Ecotoxicité comparative de l'oxyde de graphène et d'autres nanoparticules de carbone chez des organismes aquatiques modèles : d'une évaluation en conditions monospécifiques vers l'étude d'une chaîne trophique expérimentale." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30270/document.

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L'écotoxicité de différentes nanoparticules de carbone (NPC) a été évaluée chez des organismes aquatiques, en particulier chez Xenopus laevis. Il a été montré que la surface des NPC est le paramètre le plus pertinent pour décrire l'inhibition de croissance chez le xénope, indépendamment de leur forme allotropique et de leur état de dispersion. L'induction des micronoyaux a aussi été étudiée chez le xénope, et l'oxyde de graphène (GO) s'est révélé génotoxique à faible dose, résultat corroboré par l'étude de l'expression des gènes. Les mécanismes de toxicité impliqués seraient notamment liés aux fonctions oxygénées de la particule. De plus, le GO a aussi entrainé de la génotoxicité chez Pleurodeles waltl. et de la tératogénicité, des retards de développement et de l'inhibition de croissance chez Chironomus riparius. La mise en interaction de ces organismes au sein d'un mésocosme a également conduit à l'observation de génotoxicité chez le pleurodèle en présence de GO
The ecotoxicity of different carbon-based nanoparticles (CNPs) was assessed in freshwater organisms, especially in Xenopus laevis. The surface of the CNPs was shown to be the more relevant parameter to describe the growth inhibition in Xenopus, regardless of their allotropic form and their state of dispersion. Micronucleus induction was also studied in Xenopus and graphene oxide (GO) was found genotoxic at low dose. This result was in compliance with the study of genes expression. The involved toxicity mechanisms would be related to the oxidized functions of the CNP. Moreover, GO was also found responsible for genotoxicity in Pleurodeles waltl. and for teratogenicity, development delay and growth inhibition in Chironomus riparius. These organisms have finally been put together in a mesocosm, which has also led to genotoxicity in Pleurodeles in the presence of GO
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Brandenburg, Ricardo Fischer. "Nanocompósitos de polietileno com grafenos ou nanotubos de carbono." Universidade do Estado de Santa Catarina, 2014. http://tede.udesc.br/handle/handle/1653.

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Made available in DSpace on 2016-12-08T17:19:22Z (GMT). No. of bitstreams: 1 Ricardo F Brandenburg.pdf: 3039851 bytes, checksum: 3d4060b133bdc8303497115dadcc063e (MD5) Previous issue date: 2014-01-31
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The dispersion of carbon nanoparticles in polymer matrices has been studied by many researchers. This paper used nanoparticles of carbon nanotubes and graphene, in high density polyethylene matrix, making use of solution dispersion and melt dispersion. The solution dispersion used as solvent 1,2 dichlorobenzene and the melt dispersion was performed with torque rheometer. Analysis of Differential Scanning Calorimetry, Thermogravimetry, Size Exclusion Chromatography, Raman Spectroscopy, Infrared Spectroscopy Fourier Transform , analyzes of torque in the melt dispersion, nanoindentation to determine nanohardness and elastic modulus, Vickers hardness, Transmission Electron Microscopy, and Scanning Electron Microscopy with Field Emission. It was found that there was no significant change in melting temperature and crystallization of the nanocomposites. No significant change was identified in thermogravimetric analysis. The results of the elastic modulus demonstrate 22.8% increase in the use of carbon nanotubes for both methods of dispersion. The results obtained in graphene nanocomposites show that the dispersion method directly affects the properties of the nanocomposites. There was a 14% increase in tensile modulus for composites with 1% solution by graphene dispersed and scattered compositions with 5 % in melt dispersion. Analysis of Transmission Electron Microscopy and Scanning Electron Microscopy with Field Emission confirm dispersion states of carbon nanotubes dispersed by fusion , and agglomerated states of graphene in both dispersion processes, with smaller nanoplateletes of the solution dispersion compared to the melt dispersion. Crystallinity index showed similar levels in nanocomposites with carbon nanotubes and differentiated for nanocomposites with graphene, which reduces the degree of crystallinity compared to pure polymer matrix values.
A dispersão de nanopartículas de carbono em matrizes poliméricas tem sido objeto de estudo de diversos pesquisadores. Este trabalho utilizou nanopartículas de nanotubos de carbono e grafenos, em matriz de polietileno de alta densidade, fazendo-se uso de dispersão por solução e dispersão por fusão. A dispersão por solução utilizou como solvente 1,2 diclorobenzeno e a dispersão por fusão foi realizada com reômetro de torque. Foram realizadas análises de Calorimetria Diferencial Exploratória, Termogravimetria, Cromatografia de Exclusão por Tamanho, Espectroscopia RAMAN, Espectroscopia no Infravermelho com Transformada de Fourier, análises de torque na dispersão por fusão, nanoindentação para determinação de módulo de elasticidade e nanodureza, microdureza Vickers, Microscopia Eletrônica de Transmissão e Microscopia Eletrônica de Varredura com Emissão de Campo. Verificou-se que não há alteração significativa da temperatura de fusão e de cristalização dos nanocompósitos obtidos. Não foi identificado alteração significativa do comportamento térmico no ensaio de termogravimetria. Os resultados do módulo de elasticidade demonstram aumento de 22,8% na utilização de nanotubos de carbono, para os dois métodos de dispersão. Os resultados obtidos nos nanocompósitos com grafenos demonstram que o método de dispersão interfere diretamente nas propriedades dos nanocompósitos. Houve aumento de 14% no módulo de elasticidade para composições com 1% de grafeno dispersados por solução e para composições com 5% dispersados por fusão. As análises de Microscopia Eletrônica de Transmissão e Microscopia Eletrônica de Varredura com Emissão de Campo confirmam estados de dispersão de nanotubos de carbono dispersados por fusão, e estados aglomerados de grafenos em ambos os processos de dispersão, havendo dimensões menores dos nanoplateletes na dispersão por solução, em comparação à dispersão por fusão. Os índices de cristalinidade apresentaram teores semelhantes nos nanocompósitos com nanotubos de carbono e valores diferenciados para os nanocompósitos com grafenos, com redução do grau de cristalinidade em relação à matriz polimérica pura.
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Závacký, Jakub. "Technologie úpravy nanočástic pro zlepšení jejich dispergovatelnosti pro využití v cemtových kompzitech." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2021. http://www.nusl.cz/ntk/nusl-432484.

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The diploma thesis deals with the possibility of using the addition of nanoparticles to improve the properties of cement composites. The theoretical part summarizes the findings of research in this area with a focus on methods of dispersion of nanoparticles and their treatment for use in cement composites. The experimental part focuses on the comparison of methods of dispersion and plasma treatment of reduced graphene oxide (rGO) nanoparticle solutions from the point of view of the agglomeration process. During this work, a method of systematic optical/visual monitoring of sedimentation/agglomeration was developed to complement sophisticated methods such as spectrophotometry (UV/Vis) and electron microscopy (SEM). Furthermore, the effect of the addition of rGO on the properties of cement mortar, in the form of aqueous solutions prepared by the dispersion methods determined in the previous section, was investigated.
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Pacltová, Klára. "Ověřování vlastností betonů s nanočásticemi." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392361.

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This diploma thesis deals with the influence of addition of carbon nanoparticles on cement composites. The theoretical part of the diploma thesis is focused on the research of information about carbon nanoparticles, more precisely about carbon nanotubes and graphene oxide. There are summarized methods of dispersing carbon nanotubes and their effects on cement composites. The practical part follows the theoretical part of the research. In the first phase, the correct technique of graphene oxide dispersion was verified. Subsequently, the effects of graphene oxide on the mechanical properties of cement mortars were verified. In the final phase of the diploma thesis, the knowledge gained from the previous part was verified on concrete samples.
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Eneborg, Alexander. "Improvement and Characterization of Aqueous Graphene Dispersions." Thesis, KTH, Tillämpad fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-248004.

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Books on the topic "Graphene dispersion"

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Horing, Norman J. Morgenstern. Graphene. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198791942.003.0012.

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Chapter 12 introduces Graphene, which is a two-dimensional “Dirac-like” material in the sense that its energy spectrum resembles that of a relativistic electron/positron (hole) described by the Dirac equation (having zero mass in this case). Its device-friendly properties of high electron mobility and excellent sensitivity as a sensor have attracted a huge world-wide research effort since its discovery about ten years ago. Here, the associated retarded Graphene Green’s function is treated and the dynamic, non-local dielectric function is discussed in the degenerate limit. The effects of a quantizing magnetic field on the Green’s function of a Graphene sheet and on its energy spectrum are derived in detail: Also the magnetic-field Green’s function and energy spectrum of a Graphene sheet with a quantum dot (modelled by a 2D Dirac delta-function potential) are thoroughly examined. Furthermore, Chapter 12 similarly addresses the problem of a Graphene anti-dot lattice in a magnetic field, discussing the Green’s function for propagation along the lattice axis, with a formulation of the associated eigen-energy dispersion relation. Finally, magnetic Landau quantization effects on the statistical thermodynamics of Graphene, including its Free Energy and magnetic moment, are also treated in Chapter 12 and are seen to exhibit magnetic oscillatory features.
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Saito, R., A. Jorio, J. Jiang, K. Sasaki, G. Dresselhaus, and M. S. Dresselhaus. Optical properties of carbon nanotubes and nanographene. Edited by A. V. Narlikar and Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533053.013.1.

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This article examines the optical properties of single-wall carbon nanotubes (SWNTs) and nanographene. It begins with an overview of the shape of graphene and nanotubes, along wit the use of Raman spectroscopy to study the structure and exciton physics of SWNTs. It then considers the basic definition of a carbon nanotube and graphene, focusing on the crystal structure of graphene and the electronic structure of SWNTs, before describing the experimental setup for confocal resonance Raman spectroscopy. It also discusses the process of resonance Raman scattering, double-resonance Raman scattering, and the Raman signals of a SWNT as well as the dispersion behavior of second-order Raman modes, the doping effect on the Kohn anomaly of phonons, and the elastic scattering of electrons and photons. The article concludes with an analysis of excitons in SWNTs and outlines future directions for research.
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Zhou, S. Y., and A. Lanzara. The electronic structure of epitaxial graphene—A view from angle-resolved photoemission spectroscopy. Edited by A. V. Narlikar and Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533046.013.14.

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This article analyzes the electronic structure of epitaxial graphene using angle-resolved photoemission spectroscopy (ARPES). It first describes how the carbon atoms in graphene are arranged before discussing the growth and characterization of graphene samples. It then considers the electronic structure of epitaxial graphene, along with the gap opening in single-layer epitaxial graphene. It also examines possible mechanisms for the gap opening in graphene, including quantum confinement, mixing of the states between the Brillouin zone corner K points induced by scattering, and hybridization of the valence and conduction bands caused by symmetry breaking in carbon sublattices. Clear deviations from the conical dispersions are observed near the Diracpoint energy, which can be interpreted as a gap opening attributed to graphene–substrate interaction. Graphene–substrate interaction is thus a promising route for engineering the bandgap in graphene.
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Book chapters on the topic "Graphene dispersion"

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Samancı, Meryem, and Ayşe Bayrakçeken Yurtcan. "Dispersion and Characterization of Graphene in Elastomer Composite." In Graphene-Rubber Nanocomposites, 177–98. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003200444-7.

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John, Texter. "Visible Optical Extinction and Dispersion of Graphene in Water." In Graphene Science Handbook, 315–42. Boca Raton, FL : CRC Press, Taylor & Francis Group, 2016. | “2016: CRC Press, 2016. http://dx.doi.org/10.1201/b19642-20.

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Shin, Seeun, and Donghyun Bae. "The Effect of Mechanically Exfoliated Graphene Dispersion on the Mechanical Properties of Aluminum/Graphene Composites." In Light Metals 2014, 1441–42. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118888438.ch241.

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Shin, Seeun, and Donghyun Bae. "The Effect of Mechanically Exfoliated Graphene Dispersion on the Mechanical Properties of Aluminum/Graphene Composites." In Light Metals 2014, 1441–42. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-48144-9_241.

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Cesano, Federico, and Domenica Scarano. "Dispersion of Carbon-Based Materials (CNTs, Graphene) in Polymer Matrices." In Carbon for Sensing Devices, 43–75. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-08648-4_3.

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Wotring, Erik, Paramita Mondal, and Charles Marsh. "Characterizing the Dispersion of Graphene Nanoplatelets in Water with Water Reducing Admixture." In Nanotechnology in Construction, 141–48. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-17088-6_17.

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Shunin, Yuri, Stefano Bellucci, Alytis Gruodis, and Tamara Lobanova-Shunina. "CNT and Graphene Growth: Growing, Quality Control, Thermal Expansion and Chiral Dispersion." In Lecture Notes in Nanoscale Science and Technology, 207–51. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-69167-1_7.

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Alfano, M., C. Lamuta, G. Chiarello, and A. Politano. "Elastic Properties and Electron–Phonon Coupling of Graphene/Metal Interfaces Probed by Phonon Dispersion." In GraphITA, 47–59. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-58134-7_4.

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Aribou, Najoia, Zineb Samir, Yassine Nioua, Sofia Boukheir, Rajae Belhimria, Mohammed E. Achour, Nandor Éber, Luis C. Costa, and Amane Oueriagli. "Investigation of Dielectric Properties of Water Dispersion of Reduced Graphene Oxide/Water Nanofluid Composite." In Proceedings of the Sixth International Symposium on Dielectric Materials and Applications (ISyDMA’6), 95–105. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-11397-0_8.

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Fedi, Filippo, Filiberto Ricciardella, Tiziana Polichetti, Maria Lucia Miglietta, Ettore Massera, and Girolamo Di Francia. "Exfoliation of Graphite and Dispersion of Graphene in Solutions of Low-Boiling-Point Solvents for Use in Gas Sensors." In Lecture Notes in Electrical Engineering, 143–47. Cham: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-00684-0_27.

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Conference papers on the topic "Graphene dispersion"

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Grayfer, E. D., V. G. Makotchenko, A. S. Nazarov, V. S. Danilovich, Y. A. Anikin, A. S. Chubov, K. V. Shpol'vind, Sung-Jin Kim, and V. E. Fedorov. "Graphene dispersion and graphene paper from highly exfoliated graphite." In 2011 IEEE Nanotechnology Materials and Devices Conference (NMDC 2011). IEEE, 2011. http://dx.doi.org/10.1109/nmdc.2011.6155361.

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Illera, Danny, Chatura Wickramaratne, Diego Guillen, Chand Jotshi, Humberto Gomez, and D. Yogi Goswami. "Stabilization of Graphene Dispersions by Cellulose Nanocrystals Colloids." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-87830.

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The outstanding properties of single-layer graphene sheets for energy storage are hindered as agglomeration or restacking leads to the formation of graphite. The implications of the aforementioned arise on the difficulties associated with the aqueous processing of graphene sheets: from large-scale production to its utilization in solvent-assisted techniques like spin coating or layer-by-layer deposition. To overcome this, aqueous dispersions of graphene were stabilized by cellulose nanocrystals colloids. Aqueous cellulose nanocrystals dispersion highlights as a low-cost and environmentally friendly stabilizer towards graphene large-scale processing. Colloids of cellulose nanocrystals are formed by electrostatic repulsion of fibrils due to de-protonated carboxyl or sulfate half-ester functional groups. Graphene dispersions are obtained by hydrothermal reduction of electrochemically exfoliated graphene oxide in the presence of cellulose nanocrystals. This approach allows the preservation of the intrinsic properties of the nano-sheets by promoting non-covalent interactions between cellulose and graphene. The dispersions could be cast to form free-standing flexible conducting films or freeze-dried to form foams and aerogels for capacitive energy storage.
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Araneo, R., G. Lovat, and P. Burghignoli. "Dispersion analysis of graphene nanostrip lines." In 2012 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting. IEEE, 2012. http://dx.doi.org/10.1109/aps.2012.6349122.

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Tsegaye, Mikiyas S., Patrick E. Hopkins, Avik W. Ghosh, and Pamela M. Norris. "Calculating the Phonon Modes of Graphene Using the 4th Nearest Neighbor Force Constant Method." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-66726.

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Graphite has always been a very important material both industrially and academically due to its physical structure. But ever since the isolation of Graphene (a single sheet of Graphite) a few years ago, it’s been one of the most widely studied molecular systems for its potential applications in nano-electronics and other break-through areas. Some of the desirable traits of Graphene are its high thermal and electronic mobility, and its low noise properties. This paper outlines a standard method for calculating phonon dispersion curves in Graphene by making use of force constant measurements. This information is usually obtained from approximations of inter-atomic potentials, which involve derivatives of simplified potential approximations between every atom in Graphene to get the force constant tensors. In this paper, the measured values for the force constants are used in a mathematically rigorous way to calculate the Graphene phonon dispersion curves.
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Araneo, R., G. Lovat, and P. Burghignoli. "Graphene nanostrip lines: Dispersion and attenuation analysis." In 2012 IEEE 16th Workshop on Signal and Power Integrity (SPI). IEEE, 2012. http://dx.doi.org/10.1109/sapiw.2012.6222915.

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Hu, Zengrong, Guoquan Tong, Rong Xu, Lirun Zhao, Changjun Chen, Min Zhang, Yilin Sun, Huafeng Guo, and Jiale Xu. "Laser Sintered Graphene Reinforced Titanium Matrix Nanocomposites." In ASME 2016 11th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/msec2016-8562.

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Graphene reinforced titanium (Ti-Gr) nanocomposites have been prepared on AISI 4140 base plate by laser sintering process. The dispersion and survival of graphene in the Ti matrix after laser treatment were discussed. Through laser sintering, graphene sheets were dispersed uniformly into Ti matrix to form Ti-Gr nanocomposites. Microstructures and components of the nanocomposites were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and Raman spectroscopy. It was proved by SEM images, XRD patterns and Raman spectrum that graphene survived in Ti-Gr nanocomposites after laser sintering. Hardness measurements showed the laser sintered Ti-Gr nanocomposites got more than 2-fold higher in Vickers Hardness value than that of laser sintered Ti.
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SCHNEIDER, MELANIE, POURIA KHANBOLOUKI, NEKODA VAN DE WERKEN, ELIJAH WADE, REZA FOUDAZI, and MEHRAN TEHRANI. "Dispersion and Properties of Graphene Oxide and Reduced Graphene Oxide in Nanocomposites." In American Society for Composites 2018. Lancaster, PA: DEStech Publications, Inc., 2018. http://dx.doi.org/10.12783/asc33/26082.

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Kozina, O. N., L. A. Melnikov, and I. S. Nefedov. "Dispersion characteristics of hyperbolic graphene-semiconductors multilayered structure." In Saratov Fall Meeting 2014, edited by Elina A. Genina, Vladimir L. Derbov, Kirill V. Larin, Dmitry E. Postnov, and Valery V. Tuchin. SPIE, 2015. http://dx.doi.org/10.1117/12.2180053.

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Mann, Sarita, Pooja Rani, Ranjan Kumar, and V. K. Jindal. "DFT study of phonon dispersion in pure graphene." In ADVANCED MATERIALS AND RADIATION PHYSICS (AMRP-2015): 4th National Conference on Advanced Materials and Radiation Physics. AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4929251.

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Cheng, Zhenzhou, Zhen Li, Ke Xu, and Hon Ki Tsang. "Silicon waveguide dispersion changes induced by graphene overlay." In 2014 IEEE 11th International Conference on Group IV Photonics. IEEE, 2014. http://dx.doi.org/10.1109/group4.2014.6961970.

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