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Heisey, Cheryl L. "Adhesion of novel high performance polymers to carbon fibers : fiber surface treatment, characterization, and microbond single fiber pull-out test /." Diss., This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-02052007-081244/.
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Luo, Jie. "Lignin-Based Carbon Fiber." Fogler Library, University of Maine, 2010. http://www.library.umaine.edu/theses/pdf/LuoJ2010.pdf.
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Deng, Yuliang. "Carbon fiber electronic interconnects." College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/6997.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.Thesis research directed by: Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Joshi, Ninad Milind. "Study of the Effect of Unidirectional Carbon Fiber in Hybrid Glass Fiber / Carbon Fiber Sandwich Box Beams." University of Dayton / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1386188162.
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D'Angelo, Emanuele <1989>. "Carbon fiber reinforced polymers: matrix modifications and reuse of carbon fibers recovered by pyrolysis." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amsdottorato.unibo.it/8363/1/Emanuele_D_Angelo_thesis.pdf.
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Due to their extraordinary properties, Carbon Fiber Reinforced Polymers (CFRPs) are used in a growing number of fields (automotive, military, aircraft, aerospace, wind turbines, sport, civil infrastructure and leisure). Since the matrix in CFRPs is polymer-based, these composites have poor resistance to fire; additionally, when exposed to high temperatures, they can burn or lose their thermo-mechanical stability. Moreover, the recent huge and continuous development of CFRPs opened the question related to their disposal and total dependence on fossil resources. This thesis focussed on epoxy-based CFRPs. In more detail, commercial epoxy resins have been modified and replaced with bio-based alternatives, and short recycled carbon fibers composites have been produced.
Two new bentonite-based organoclays were prepared with low cost reactants and mild reactions conditions and used to modify the flame behaviour of a commercial epoxy resin. The epoxy-modified resin flame behaviour was evaluated by cone-calorimeter and some significant improvements with just a 3 %wt loading level of organoclay were obtained. Furthermore, the possibility to recover and reuse carbon fibers by pyrolysis of CFRPs waste was studied: a validation of the recycling conditions and the treatments required to reuse recycled carbon fibers were assessed in order to obtain clean fibers and promote fiber/matrix adhesion in epoxy composites. Recycled carbon fiber were then used in a lab-scale composite manufacturing process and comparable mechanical properties for virgin and recycled short carbon fiber composites were achieved when an optimized coupled pyrolysis/oxidative process to CFRPs waste is applied. Finally, more sustainable CFRPs have been produced and characterized coupling highly bio-based epoxy systems, appropriately modified and optimized, and recycled carbon fibers. This latter work represents the first attempt aimed at replacing petroleum- BPA-based epoxy resins and high cost short virgin carbon fibers in the future CFRPs manufacturing processes.
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Newcomb, Bradley Allen. "Gel spun PAN and PAN/CNT based carbon fibers: From viscoelastic solution to elastic fiber." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54881.
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This study focuses on the processing, structure, and properties of gel spun polyacrylonitrile (PAN) and polyacrylonitrile/carbon nanotube (PAN/CNT) carbon fibers. Gel spun PAN based carbon fibers are manufactured beginning with a study of PAN dissolution in an organic solvent (dimethylformamide, DMF). Homogeneity of the PAN/DMF solution is determined through dynamic shear rheology, and the slope of the Han Plot (log G’ vs log G’’). Solutions were then extruded into gel spun fibers using a 100 filament fiber spinning apparatus in a class 1000 cleanroom. Fibers were then subjected to fiber drawing, stabilization, and carbonization, to convert the PAN precursor fiber into carbon fiber. Carbon fiber tensile strength was shown to scale with the homogeneity of the PAN/DMF solution, as determined by the slope of the log G’ vs log G’’ plot. After the development of the understanding between the homogeneity of the PAN/DMF solutions on the gel spun PAN based carbon fiber tensile properties, the effect of altering the fiber spinning processing conditions on the gel spun PAN based carbon fiber structure and properties is pursued. Cross-sectional shape of the gel spun PAN precursor fiber, characterized with a stereomicroscope, was found to become more circular in cross-section as the gelation bath temperature was increased, the amount of solvent in the gelation bath was increased, and when the solvent was switched from DMF to dimethylacetamide (DMAc). Gel spun fibers were then subjected to fiber drawing, stabilization, and carbonization to manufacture the carbon fiber. Carbon fibers were characterized to determine single filament tensile properties and fiber structure using wide-angle x-ray diffraction (WAXD) and high resolution transmission electron microscopy (HRTEM). It was found that the carbon fiber tensile properties decreased as the carbon fiber circularity increased, as a result of the differences in microstructure of the carbon fiber that result from differences in fiber spinning conditions. In the second half of this study, the addition of CNT into the PAN precursor and carbon fiber is investigated. CNT addition occurs during the solution processing phase, prior to gel spinning. As a first study, Raman spectroscopy is employed to investigate the bundling behavior of the CNT after gel spinning and drawing of the PAN/CNT fibers. By monitoring the peak intensity of the (12,1) chirality in the as-received CNT powder, and in differently processed PAN/CNT fibers, the quality of CNT dispersion can be quickly monitored. PAN/CNT fibers were then subject to single filament straining, with Raman spectra collected as a function of PAN/CNT filament strain. As a result of the PAN/CNT strain, stress induced G’ Raman band shifts were observed in the CNT, indicating successful stress transfer from the surrounding PAN matrix to the dispersed CNT. Utilization of the shear lag theory allows for the calculation of the interfacial shear strength between the PAN and incorporated CNT, which is found to increase as the quality of CNT (higher aspect ratio, increased graphitic perfection, and reduced impurity content), quality of CNT dispersion, and fiber drawing increase. PAN/CNT fibers were then subjected to stabilization and carbonization for the manufacture of gel spun PAN/CNT based carbon fibers. These fibers were then characterized to investigate the effect of CNT incorporation on the structure and properties of the carbonized fibers. The gel spun PAN/CNT based carbon fibers were compared to commercially produced T300 (Toray) and IM7 (Hexcel) carbon fibers, and gel spun PAN based carbon fiber. Fiber structure was determined from WAXD and HRTEM. Carbon fibers properties investigated include tensile properties, and electrical and thermal conductivity. PAN/CNT based carbon fibers exhibited a 103% increase in room temperature thermal conductivity as compared to commercially available IM7, and a 24% increase in electrical conductivity as compared to IM7. These studies provide a further understanding of the processing, structure, property relationships in PAN and PAN/CNT based carbon fibers, beginning at the solution processing phase. Through the manufacture of more homogeneous PAN/DMF solutions and investigations of the fiber spinning process, gel spun PAN based carbon fibers with a tensile strength and modulus of 5.8 GPa and 375 GPa, respectively, were successfully manufactured in a continuous carbonization facility. Gel spun PAN/CNT based carbon fibers exhibit room temperature electrical and thermal conductivities as high as 74.2 kS/m and 33.5 W/m-K.
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Hoque, A. K. M. Azizul. "Synthesis of catalyst particles for carbon fiber growth in a Vapor Grown Carbon Fiber reactor." Ohio University / OhioLINK, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1174617623.
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Fedorenko, O. O., and J. K. Warchoł. "Structural and mass transfer characteristics of carbon-fiber materials." Thesis, Київський національний університет технологій та дизайну, 2017. https://er.knutd.edu.ua/handle/123456789/6750.
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Hengstermann, M., N. Raithel, A. Abdkader, M. M. B. Hasan, and Ch Cherif. "Development of new hybrid yarn construction from recycled carbon fibers for high performance composites: Part-I: basic processing of hybrid carbon fiber/polyamide 6 yarn spinning from virgin carbon fiber staple fibers." Sage, 2016. https://tud.qucosa.de/id/qucosa%3A35421.
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The availability of a considerable amount of waste carbon fiber (CF) and the increased pressure to recycle/reuse materials at the end of their life cycle have put the utilization of recycled CF (rCF) under the spotlight. This article reports the successful manufacturing of hybrid yarns consisting of staple CF cut from virgin CF filament yarn and polyamide 6 fibers of defined lengths (40 and 60 mm). Carding and drawing are performed to prepare slivers with improved fiber orientation and mixing for the manufacturing of hybrid yarns. The slivers are then spun into hybrid yarns on a flyer machine. The investigations reveal the influence of fiber length and mixing ratio on the quality of the card web, slivers and on the strength of the hybrid yarns. The findings based on the results of this research work will help realize value-added products from rCF on an industrial scale in the near future.
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Tsang, Lina. "High modulus carbon fiber/titanium laminates." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/34584.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2006.Includes bibliographical references (leaves 38-39).
Titanium has been used to meet ever-stricter standards for high-temperature performance, creep resistance, low weight and high strength. Having low density, a high melting point, and high tensile strength, it seems like the perfect material for numerous applications. For structural applications where flexural stiffness and strength play the most important role, titanium's high cost can be a restrictive factor. The cost-effectiveness of the material can be increased by using it together with other less expensive high strength and low weight materials in the form of composite laminates. In this investigation, laminates were fabricated using inorganic matrix/high modulus carbon fiber composites with titanium sheets. Laminates were tested in three-point bending to assess the performance of the upgrade. The results show that combining Geopolymer high modulus carbon composites with titanium sheets significantly increases the performance. Laminates provide a lower cost solution for given stiffness and weight requirements compared with other common structural materials, such as steel and aluminum.
by Lina Tsang.
M.Eng.
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Liang, Jianghong. "Single Wall Carbon Nanotube/Polyacrylonitrile Composite Fiber." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/7613.
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Single Wall Carbon Nanotubes (SWNTs), discovered in 1993, have good mechanical, electrical and thermal properties. Polyacrylonitrile (PAN) is an important fiber for textiles as well as a precursor for carbon fibers. PAN has been produced since 1930s.
In this study, we have processed SWNT/PAN fibers by dry-jet wet spinning. Purified SWNT, nitric acid treated SWNTs, and benzonitrile functionalized SWNTs have been used. Fiber processing was done in Dimethyl Formamide (DMF) and coagulation was done in DMF/water mixture. The coagulated fibers were drawn (draw ratio of 6) at 95 oC.
Structure, orientation, and mechanical properties of these fibers have been studied. The cross-sections for all the fibers are not circular. Incorporation of SWNT in PAN results in improved mechanical properties, tensile modulus increased from 7.9 GPa for control PAN to 13.7 GPa for SWNT/PAN composite fiber, and functionalized SWNTs result in higher improvements with tensile modulus reaching 17.8 GPa for acid treated SWNT/PAN composite fibers. The theoretical analysis suggests that observed moduli of the composite fibers are consistent with the predicted values.
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Fernandes, Henrique. "Fiber orientation analysis of carbon fiber-reinforced polymers by infrared thermography." Doctoral thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/27294.
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L’utilisation de Matériaux Composites est de plus en plus courante dans plusieurs applications, notamment dans les structures aéronautiques où des pièces de forme complexe sont fort demandées. Dans ces matériaux, la disposition ou l’orientation des fibres l’une par rapport à l’autre, la concentration de celles-ci, et leur distribution sont des facteurs qui ont une influence notable sur la résistance et d’autres propriétés des composites renforcés de fibres. Ainsi, on a besoin de développer des techniques d’essai pour évaluer la teneur en fibres. Des méthodes destructrices peuvent être utilisées pour évaluer les fibres dans un échantillon composite par exemple, en évaluant une section de coupe du matériau après polissage de la surface par microscopie. Cependant, l’approche destructrice n’est pas toujours une option puisque l’échantillon est endommagé après l’inspection et probablement impropre à l’utilisation. Ainsi, les techniques de Contrôle non-destructif (CND) doivent être utilisées dans certains cas pour évaluer le contenu de la matière fibreuse. Dans cette thèse, la thermographie infrarouge, une technique de CND bien connue, est utilisé afin d’évaluer l’orientation des fibres de matériaux composites, à la surface et sous la surface de pièces plates ainsi que de pièces de forme complexes. Plus précisément, l’ellipsométrie thermique utilisant une source de point laser de chauffage (statique) et une source de chauffage en ligne produit par balayage en vol du point laser (dynamique) sont employés. L’évaluation de l’orientation de la fibre sur des pièces de forme complexe est accomplie avec succès en raison de la fusion d’un modèle en trois dimensions de la surface de l’échantillon avec les données infrarouge obtenues par l’inspection d’ellipsométrie thermique. Le matériau qui va être inspecté dans ce projet est le Carbone/Polyether-Ether-Ketone (PEEK) réalisé par disposition de flocons de fibres appelée Randomly-Oriented Unidirectional Strand (ROS).The use of Composite Materials (CM) is growing more and more every day in several applications, especially in aeronautic structures where complex shaped parts are highly demanded. The arrangement or orientation of the fibers relative to one another, the fiber concentration, and the distribution all have a significant influence on the strength and other properties of fiber reinforced composites. Thus, one needs to develop testing techniques to assess fiber content. Destructive methods can be employed to evaluate the fiber on a composite, e.g. cutting a section of the material, polishing the area and evaluating it by microscopy. However, the destructive approach is not always an option since the sample will be ‘damaged’ after the inspection and probably unfit for use. Therefore, Non-Destructive Testing and Evaluation (NDT& E) techniques must be employed in some cases to assess the material’s fiber content. In this thesis, InfraRed Thermography (IRT), a well-known NDT& E technique, is used in order to assess fiber orientation of composite materials on the surface and beneath the surface of booth flat and complex shaped parts. More specifically, Thermal Ellipsometry (TE) using a laser spot heating source (static) and a line heating source produced by a flying laser spot inspection (dynamic) are employed. Fiber orientation assessment on complex shaped parts is successfully accomplished due to the merge of a Three-Dimensional (3D) model of the part’s surface with the InfraRed (IR) data obtained by the TE inspection. The specimens that are going to be inspected in this project are Carbon/Polyether-Ether-Ketone (PEEK) plates reinforced by Randomly-Oriented Unidirectional Strand (ROS) of unidirectional slit tape.
O uso de Materiais Compósitos tem crescido mais e mais a cada dia em várias aplicações, especialmente em estruturas aeronáuticas onde peças em forma de complexos sõ extremamente procurados. O arranjo ou orientação das fibras com relação umas às outras, a concentração de fibra, e sua distribuição tem todos um grande impacto na força, rigidez e outras propriedades de materiais compósitos reforçados com fibras. Assim, se faz necessário o desenvolvimento de técnicas capazes de avaliar o conteúdo fibroso destes materiais. Métodos destrutivos podem ser empregados para avaliar as fibras em um material compósito, por exemplo cortando-se uma secção do material, polindo a área e avaliado a região com um microscópio. Entretanto, a abordagem destrutiva nõ é sempre uma opção uma vez que após o ensaio a peça ficará danificada e provavelmente imprópria para uso. Deste modo, ensaios não-destrutivos devem ser empregados em certos casos para avaliar o conteúdo fibroso do material. Nesta tese, termografia infravermelha, uma conhecida técnica de ensaios não-destrutivo, é usada para acessar a orientação das fibras de materiais compósitos na superfície e sub-superfície de amostras planas bem como de amostras com formas complexas. Mais especificamente, elipsometria térmica usando fonte de aquecimento ponto de laser (estático) e uma fonte de aquecimento em linha produzida por uma inspeção de ponto voador (dinâmico) são empregadas. Avaliação de orientação de fibra em amostras de formas complexas é realizada com sucesso graças a fusão de um modelo tridimensional da superfície da amostra e os dados infravermelhos obtidos com o ensaio de elipsometria térmica. As amostras inspecionadas durante este projeto são feitas Carbono/Polyether-Ether-Ketone (PEEK) reforçadas com Randomly-Oriented Unidirectional Strand (ROS).
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Lim, Wei Jun. "Frictional Properties of Carbon-Carbon Composites and Their Relation to Fiber Architecture and Microstructure." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/theses/2055.
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The use of carbon-carbon (C/C) composites for clutch application requires a basic understanding of the structural characteristics of the composites that control their frictional and engineering properties. These are related to the microstructure of the matrix and fiber architecture, with the character of fiber/matrix interface and type of defects, porosity and microcracks being the most relevant. The purpose of this study is to examine and characterize the relation between the fiber architecture of selected C/C composites and its relation to their frictional properties when subjected to different normal forces and relative humidity. Friction tests is conducted using a Brüker Universal Friction Tester (UFT). This study also seeks to characterize and analyze the microstructure and fiber architecture through Polarized Light Microscopy, X-Ray Diffraction and Ultrasound Scans. This study shows that the Coefficient of Friction (COF) at constant normal force and RPM are always slightly lower for the samples with surface fibers orientated at 45° relative to the direction of rotation compared to samples with surface fibers orientated 0/90° at 50% relative humidity. The percent difference ranges from 1.62% to 15.30%. However, at 85% relative humidity, the average COF at the constant normal force and RPM are always slightly higher for the 45° compared to 0/90° samples for Rotor samples, while in contrast the average COF are always lower for the 45° samples compared to 0/90° samples for Stator samples. The percent difference ranges from 3.14% to 35.46%. This study found significant differences between the 0/90° samples and the 45° samples. There is indication that the fiber orientation can cause differences between frictional properties even if the clutches are made from the same material. The change in humidity also significantly changes the resulting COF.
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Choi, Young Ho. "Polyacrylonitrile / carbon nanotube composite fibers: effect of various processing parameters on fiber structure and properties." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42902.
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This study elucidates the effect of various processing parameters on polyacrylonitrile (PAN) /carbon nanotube (CNT) composite fiber structure and properties. Interaction between PAN and MWNT enabled the gel-spun PAN/MWNT composite fiber to be drawn to a higher draw ratio, than the control PAN fiber, resulting in the composite fiber tensile strength value as high as 1.3 GPa. PAN/MWNT composite fibers were stabilized and carbonized, and the resulting fibers have been characterized for their structure and properties. The effect of precursor fiber shelf-time on the mechanical properties of the gel-spun PAN/MWNT composite fibers is also reported. A rheological study of PAN-co-MAA/few wall nanotube (FWNT) composite solution has been conducted. At low shear rates, the network of FWNTs contributes to elastic response, resulting in higher viscosity and storage modulus for the composite solution as compared to the control solution. On the other hand, at high shear rates, the network of FWNTs can be broken, resulting in lower viscosity for the composite solution than that for the control solution. Larger PAN crystal size (~16.2 nm) and enhanced mechanical properties are observed when the fiber was drawn at room temperature (cold-drawing) prior to being drawn at elevated temperature (~ 165 °C; hot-drawing). Azimuthal scan of wide angle X-ray diffraction (WAXD) and Raman G-band intensities were used for the evaluation of Herman's orientation factor for PAN crystal (fPAN) and FWNT (fFWNT), respectively. Significantly higher nanotube orientation was observed than PAN orientation at an early stage of fiber processing (i.e during spinning, cold-drawing). Differential scanning calorimetry (DSC) revealed that PAN-co-MAA fiber can be converted into cyclic structure at milder conditions than those for PAN. Continuous in-line stabilization, carbonization, and characterization of the resulting carbon fibers were carried out. Rheological and fiber spinning studies have also been carried out on PAN-co-MAA/VGCNF (vapor grown carbon nano fiber). The diameter of PAN-co-MAA/VGCNF composite fiber is smaller than that of the PAN-co-MAA control fiber with same draw ratio due to the suppressed die-swell in the presence of VGCNF. The mechanical properties of PAN-co-MAA control and PAN-co-MAA/VGCNF composite fibers were characterized. Crystalline structure and morphology of the solution-spun PAN-co-MAA/VGCNF fibers are characterized using WAXD and scanning electron microscopy (SEM), respectively. The volume fraction of PAN-CNT interphase in PAN matrix has been calculated to illustrate the impact of CNTs on structural change in PAN matrix, when ordered PAN molecules are developed in the vicinity of CNTs during fiber processing. The effect of PAN-CNT interphase thickness, CNT diameter, and mass density of CNT on volume fraction of PAN-CNT interphase has been explored.
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Steiner, Stephen Alan III. "Carbon nanotube growth on challenging substrates : applications for carbon-fiber composites." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/71272.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, February 2012.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
"December 2011." Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 305-315).
Nanoengineered hierarchal fiber architectures are promising approaches towards improving the inter- and intralaminar mechanical properties (e.g., toughness and strength) and non-mechanical properties of advanced fiber-reinforced composites such as graphite/epoxy. One fiber architecture of particular interest is carbon fiber coated with radially-aligned arrays of carbon nanotubes (CNTs), which can enable through-thickness and interply matrix reinforcement of carbon-fiber-reinforced composites while simultaneously providing additional multifunctional benefits such as electrical and thermal conductivity enhancement. Growth of CNTs on carbon fibers can be achieved by chemical vapor deposition (CVD) techniques, however previous processes for doing so have resulted in a significant reduction in the tensile strength and stiffness of the carbon fibers. This thesis aims to develop an understanding of catalyst-substrate and CVD environment-substrate interactions relevant to maintaining fiber mechanical properties in the growth of CNTs on carbon fibers by CVD and to use this understanding to develop practical approaches for growing CNTs on carbon fibers that simultaneously preserve fiber properties. Novel oxide-based catalysts are demonstrated for the first time to be effective for both CNT growth and graphitization of amorphous carbon and are characterized using in situ metrology. These catalysts show promise for use on substrates that exhibit sensitivity to conventional metal catalysts (such as carbon fibers). New CVD processing techniques based on materials properties unique to this class of catalysts are presented and explored. Coatings for enabling growth of aligned CNTs on carbon fibers, coatings for improving adhesion of materials to carbon fibers, and coatings for facilitating low-temperature growth of CNTs on carbon fibers are developed. The mechanochemical responses of carbon fibers to high-temperature processing, exposure to CVD gases relevant for CNT growth, and in situ tensioning during CVD growth at high temperatures are investigated. Methods for growing CNTs on carbon fibers that enable aligned CNT morphologies and that preserve fiber properties are presented. A new system for optimizing CNT growth on carbon fibers with special considerations for oxide-based catalysts is described. Finally, recommendations for manufacturing hierarchal carbon fibers for composites in an industrially practical way are made.
by Stephen Alan Steiner III.
Ph.D.
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Visosky, Mark Michael. "Characterization of carbon fiber flocked cathode materials." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41397.
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Song, Yi. "Multifunctional Composites Using Carbon Nanotube Fiber Materials." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1353156345.
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Lee, Jaewoo. "Thermoplastic Composite with Vapor Grown Carbon Fiber." Ohio University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1127335929.
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Alessa, Hassan Ali. "Delamination in Hybrid Carbon/Glass Fiber Composites." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1399037290.
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Becker-Staines, Anna [Verfasser]. "Surface modification of carbon fibers : improvement of the dissipative properties of carbon fiber reinforced plastics / Anna Becker-Staines." Paderborn : Universitätsbibliothek, 2020. http://d-nb.info/1206636858/34.
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Caba, Aaron C. "Characterization of Carbon Mat Thermoplastic Composites: Flow and Mechanical Properties." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/29104.
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Carbon mat thermoplastics (CMT) consisting of 12.7 mm or 25.4 mm long, 7.2 micrometer diameter, chopped carbon fibers in a polypropylene (PP) or poly(ethylene terephthalate) (PET) thermoplastic matrix were manufactured using the wetlay technique. This produces a porous mat with the carbon fibers well dispersed and randomly oriented in a plane. CMT composites offer substantial cost and weight savings over typical steel construction in new automotive applications. In production vehicles, automotive manufacturers have already begun to use glass mat thermoplastic (GMT) materials that use glass fiber as the reinforcement and polypropylene as the matrix. GMT parts have limitations due to the maximum achievable strength and stiffness of the material. In this study the glass fibers of traditional GMT are replaced with higher strength and higher stiffness carbon fibers.
The tensile strength and modulus and the flexural strength and modulus of the CMT materials were calculated for fiber volume fractions of 10-25%. Additionally, the length of the fiber (12.7 mm or 25.4 mm) was varied and four different fiber treatments designed to improve the bond between the fiber and the matrix were tested. It was found that the fiber length had no effect on the mechanical properties of the material since these lengths are above the critical fiber length. The tensile and the flexural moduli of the CMTs were found to increase linearly with the FVF up to 25% FVF for some treatments of the fibers. For the other treatments the linearly increasing trend was valid up to 20% FVF, then stiffness either stayed constant or decreased as the FVF was increased from 20% to 25% . The strength versus FVF curves showed trends similar to those of the modulus versus FVF curves. It is shown that choosing an appropriate sizing can extend the usable FVF range of the CMT by at least 5%. Published micromechanical relations over-predicted the tensile modulus of the composite by 20-60%. An empirical fiber efficiency relation was fit to the experimental data for the tensile modulus and the tensile strength giving excellent agreement with the experimental results.
Flow tests simulating the compression molding process were conducted on the CMT to determine what factors affect the flow viscosity of the CMT. The melt viscosity of the neat PP was measured using cone and plate rheometry at temperatures between 180°C–210°C and was fit with the Carreau relation. The through thickness packing stress of the CMT mat was measured for FVFs of 8-40% and was found to follow a power law behavior based on the local bending of fibers up to a FVF of 20.9%. Above this FVF the power law exponent decreases, and this is attributed to fracture of some of the fibers. Heated platens were used to isothermally squeeze the CMT at axial strain rates of 0.02-6 s^-1. The plot of the load-displacement behavior for the 10% FVF CMT was similar in shape to that for a fluid with a yield stress. For FVFs of 15-25% the load-displacement curves showed a load spike at the beginning of the flow, then followed the curve for a fluid with a yield stress. The matrix was burned off the squeezed samples, and the remaining carbon mat was dissected and visually inspected. It was found that fiber breakage increased and fiber length decreased as the FVF of the sample was increased.Ph. D.
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Adusei, Paa Kwasi. "Carbon Nanotube-Based Composite Fibers for Supercapacitor Application." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1561996824580323.
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Fagan, Danny T. "Electrochemical and thermal desorption analysis of glassy carbon and carbon fiber surfaces /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487584612164174.
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Zhang, Qiuhong. "Carbon Nanotubes on Carbon Fibers: Synthesis, Structures and Properties." Dayton, Ohio : University of Dayton, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1272515887.
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Thesis (Ph.D. in Materials Engineering) -- University of Dayton.Title from PDF t.p. (viewed 06/23/10). Advisor: Liming Dai. Includes bibliographical references (p. 136-162). Available online via the OhioLINK ETD Center.
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Decker, Brandon Richard. "A method of strengthening monitored deficient bridges." Diss., Kansas State University, 2007. http://krex.ksu.edu/dspace/bitstream/2097/516/1/BrandonDecker2007.pdf.
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Ketterer, Justin M. "Fatigue crack initiation in cross-ply carbon fiber laminates." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29697.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2010.Committee Chair: Dr. Steve Johnson; Committee Member: Dr. Jianmin Qu; Committee Member: Dr. Rick Neu. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Pandolfi, Carlo. "Experimental characterization of carbon-fiber-reinforced polymer laminates." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/9777/.
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The goal of this thesis is to make static tensile test on four Carbon Fiber Reinforced Polymer laminates, in such a way as to obtain the ultimate tensile strength of these laminates; in particular, the laminates analyzed were produced by Hand Lay-up technology. Testing these laminates we have a reference point on which to compare other laminates and in particular CFRP laminate produced by RTM technology.
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Castro, Gabriel. "Drilling carbon fiber reinforced plastic and titanium stacks." Pullman, Wash. : Washington State University, 2010. http://www.dissertations.wsu.edu/Thesis/Spring2010/g_castro_042210.pdf.
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Thesis (M.S. in mechanical engineering)--Washington State University, May 2010.Title from PDF title page (viewed on July 16, 2010). "School of Engineering and Computer Science." Includes bibliographical references (p. 109-112).
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Nettles, Alan Tate. "Residual property assessment of impacted carbon fiber composites." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/8649.
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Wang, R., Z. Cao, L. Hao, Q. Wang, W. Liu, W. Jiao, and Y. Fan. "Healing Carbon Fiber/Polymer Composites by Resistive Heating." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35277.
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Interface is the key region which determines, to a great extent, the set of properties of all
heterogeneous systems, including composite materials. We reported interface healing of carbon fiber
reinforced thermoplastic composite material via resistive heating. The carbon fiber, T700 carbon fiber,
with a resistivity of 1.66·10-3 Ω·cm was used as the heating element while the matrix is polyarylether
sulfone with cardo. Micro-droplet experiment was used to study the interface strength before and after
heating to determine the healing efficiency. The measurement shows (experimental results show) that
resistive heating is an efficient way to heal cracks near interface.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35277
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Anderson, Eric Carlton. "Design and Optimization of Carbon-Fiber Chassis Panels." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/48436.
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Each year, the Virginia Tech (VT) Formula SAE (FSAE) team creates a high performance car to compete against 120 teams from around the world in a series of dynamic events evaluating acceleration, maneuverability, and handling. In an effort to improve upon the VT 2013 car, the torsional stiffness of the chassis was increased. Increasing the torsional stiffness of the chassis allows the suspension to be more precisely tuned, resulting in a better overall performance. An investigation was conducted into methods for improving the chassis stiffness, and it was determined that many state-of-the-art vehicles from go-karts to super cars incorporate strength-bearing, tailored advanced composite materials in their structure. Examples of components that use composites in vehicles include sandwich structures in load-bearing panels, layups in the skin of vehicles for aesthetic purposes and carbon-fiber frame tubes. The VT FSAE car already includes untailored carbon-fiber panels on the bottom and sides of the structure for packaging and aerodynamic purposes. By integrating and optimizing these carbon-fiber panels, the torsional stiffness and therefore overall performance of the structure may be increased.
This thesis explores composite testing, optimization methods, experimental and computational analysis of the chassis, and results. The fiber orientation of the panels may be optimized because carbon-fiber composite materials are generally anisotropic. Therefore the composite materials can be tailored to maximize the stiffness, resulting in the optimum stiffness per added weight. A good measure for testing stiffness per added weight is through measuring natural frequencies because natural frequency is proportional to stiffness per unit mass. A computer program was developed in MATLAB to optimize the composite configuration, and uses an objective function involving the first three natural frequencies of the original steel space frame chassis and the first three natural frequencies of the steel chassis augmented with three composite panels. The composite material properties were determined using specimen tensile testing and checked with finite elements. The natural frequencies of the half-scale chassis were determined experimentally, compared to the simulated version, and varied by less than seven percent. The optimization of the full-scale model determined that eight layers of optimized, integrated carbon-fiber composite panels will increase the first, second, and third natural frequencies by sixteen, twenty-six, and six percent, respectively. Natural frequency increases of these amounts show that by using tailored, load-bearing composite panels in the structure, the torsional stiffness of the structure increases, resulting in easier suspension tuning and better performance at the VT FSAE competitions.Master of Science
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Ohwaki, Takeshi. "Surface characterization of carbon fiber by infrared spectroscopy." Case Western Reserve University School of Graduate Studies / OhioLINK, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=case1060789332.
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Paneru, Nav Raj. "Carbon Fiber Reinforced Polymer (CFRP) Tendons in Bridges." University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1544741841522648.
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Patlapati, Ravinarayana Reddy Tejas. "Interlayer toughening of carbon-fiber/benzoxazine composite laminates." Thesis, California State University, Long Beach, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10264601.
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Carbon-fiber composites are increasingly employed in the Aerospace and Automotive industries owing to their lightweight and excellent mechanical properties. However, this class of material, when subjected to out-of-plane loads, is often susceptible to an internal damage in the form of delamination that can severely reduce its load bearing capacity. Several toughening methods including the implementation of thermoplastic materials are used to increase the damage tolerance of the polymer-matrix composites. In particular, non-woven thermoplastic veils, when used as interleaving materials between the plies in a composite structure, is extremely efficient at improving the interlaminar (delamination) fracture toughness and impact-resistance of composites. In addition, the toughening of the polymer matrix, if not adversely affecting the manufacturing process, can result in an increase in the toughness-related properties of composite laminates such as the resistance to micro-cracking under thermal-cycling conditions.
In this study, the effects of matrix toughening and interleaving of the composite with non-woven Polyamide (PA) veils on the Interlaminar Fracture Toughness (ILFT) of Carbon-fiber/Benzoxazine composites are investigated. Formulated Benzoxazine (BZ) resins in non-toughened and toughened variants along with several non-woven PA veils with different melt temperatures are used to manufacture composite laminates through the Vacuum Assisted Resin Transfer Molding (VARTM) process. The ILFT of composites is measured by obtaining the resistance to crack propagation in the interlayer under tensile forces (Mode-I ILFT) or shear forces (Mode-II ILFT). The critical strain energy release rate (Gc) recorded during interlaminar fracture gives a measure of the ILFT of a composite.
The laminates interleaved with the PA veils show an increase of nearly 50% for the Mode-I crack initiation (GIc initiation), regardless of the melt temperature of the PA veils. The Mode-I crack propagation (GIc propagation) of the laminate increases by using the PA veils with melt temperatures lower than the cure temperature of the BZ resin.
In the Mode-II ILFT (GIIc) tests, the laminates interleaved with the PA veils show a significant impact on the GIIc values, as increases of nearly 170% are observed. A strong correlation between PA melt temperatures and the GIIc values is noted. The greatest GIIc values are noted when the melt temperature of the PA veil is greater than the cure temperature of the BZ resin.
The matrix toughness plays a significant role in affecting the GIc values. The laminates manufactured with the toughened BZ resin result in the greatest increase in the GIc values. In contrary, the use of the toughened BZ resin does not result in an improvement in the GIIc values.
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Larsson, Johan. "Bearing Strenght of Thin ply Carbon fiber Laminates." Thesis, KTH, Lättkonstruktioner, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-239036.
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The lighter an object is the easier it is to send into space. This principle is what drives the never ending hunt for lighter structures in the space industry. One way to reduce weight is to replace existing materials with lighter ones. Polymer matrix composites are such materials, as their density is lower than both steel and aluminium. The company RUAG Space produces a payload separating system that operates by clamping the payload using a clamp band to the rocket and releasing the payload by releasing the tension in the band. The current band is made in aluminium but RUAG seeks to build them using carbon fiber reinforced epoxy instead. Earlier projects have shown that carbon fiber fulfills the basic requirements, but has insufficient bearing strength to handle the loads at the bolted joints to the release mechanism. Research suggests that making the individual layers of carbon fiber thinner will increase the bearing strength and so in this project test specimen have been manufactured using thick and thin carbon fiber layers. These specimen were then subjected to bearing loads and the response was observed. The result showed that the ultimate bearing strength only increased a small amount with thin plies, but the onset of damage came at 47% higher stress levels compared to thick plies, suggesting a more brittle behavior. Since the onset of damage is the most important factor for RUAG the use of thin plies produced very positive results and could be a viable solution to increase the bearing strength in the clamp band.Inom rymdindustrin är vikten på olika komponenter en väldigt viktig egenskap, i och med att det är lättare att skjuta upp en lätt produkt i rymden än en tung. På grund av detta finns det en konstantsträvan inom industrin att bygga lättare uppskjutningsriggar. Ett sätt att minska vikten är att använda lättare konstruktionsmaterial. Polymera fiberkompositer är sådana material, de har mekaniska egenskaper som är ungefär lika bra som hos metaller, men har lägre densitet. RUAG Space tillverkar ett klampförband som håller fast nyttolasten vid det sista raketsteget under en uppskjutning. Detta band är tillverkat i aluminium, men det finns intresse av att tillverka det i kolfiberförstärkt epoxy. Tidigare projekt har visat att kolfiberepoxy uppfyller de globala kraven på styrka och styvhet, men att hålkantsstyrkan är otillräcklig vid de skruvförband som finns i släppmekanismen. Forskning tyder på att hålkantsstyrkan kan ökas för kompositmaterial om de individuella lagren i laminatet görs tunnare. I det här projektet tillverkades laminat av tunna och tjocka kolfiberskikt. Av dessa laminat tillverkades provstavar som sedan blev utsatta för hålkantslast. Resultatet från dessa tester visade att provstavarna med tunna skikt kunde utsättas för 47% högre last än de med tjocka skikt innan skada började uppstå. Med detta resultat drogs slutsatsen att kolfiber med tunna skikt är en möjlig ersättare till aluminium i klampförbandet.
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Kim, Kun San. "Adhesion of graphite fibers to polycarbonate matrix : the role of fiber surface treatment." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/8569.
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Breña, Sergio F. "Strengthening reinforced concrete bridges using carbon fiber reinforced polymer composites /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004223.
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Gurung, Bijay. "Measurement of the fiber/matrix interfacial strength of carbon carbon composites by nanoindentation /." Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1324381961&sid=32&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Thesis (M.S.)--Southern Illinois University Carbondale, 2007."Department of Mechanical Engineering and Energy Processes." Includes bibliographical references (leaves 105-109). Also available online.
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Lewis, Diana J. (Diana Jean). "Interlaminar reinforcement of carbon fiber composites from unidirectional prepreg utilizing aligned carbon nanotubes." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/106679.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 113-119).
Advanced laminated composites suffer from a lack of out-of-plane strength and toughness, leading to delamination and other types of interlaminar failure. Aligned carbon nanotubes (A-CNTs) placed at the interlayer between plies of an aerospace grade carbon fiber reinforced plastic composite (CFRP) have been shown to increase interlaminar toughness while improving laminate strength. While this architecture, known as 'nanostitch', has proven beneficial, morphological changes in the A-CNT layer and their effect on the composite properties has not been studied. This thesis explores the effect of varying the A-CNT height and the layup technique on the resulting interlaminar region morphology and static short beam strength (SBS) in shear, of a quasi-isotropic layup using Hexcel IM7/8552 carbon fiber aerospace composite prepreg. In addition, fatigue testing was performed on a selected A-CNT height to generate a SBS fatigue life curve. Interface morphology and laminate damage were imaged via optical and scanning electron microscopy of cross-sections and crack surfaces, and micro-computed tomography was used to generate 3D reconstructions of some coupons. Results from static testing indicate that the A-CNT reinforcement of the interlaminar region increase the SBS by 8.5%, regardless of height (in the 5-65 micron range studied) or the two different layup techniques. This indifference to forest morphology is attributed to damage primarily occurring outside of the reinforced area, indicating that the interlaminar region is sufficiently reinforced by all A-CNT heights considered. Fatigue-life data shows a threefold increase in lifespan for the A-CNT reinforced material. All A-CNT forests affected the interface morphology, increasing the average interlayer thickness by inducing resin agglomerations near the CNT layer. This agglomeration results from resin-rich defects in the original prepreg material. Ancillary tasks involved in generating this thesis included inventing a method of measuring A-CNT forest height using an optical microscope, introducing water into the CNT growth process and controlling the furnace starting temperature to stabilize the height, altering the layup method to generate desired morphologies, and proposing a 'hot-load' system for the furnace to increase the CNT forest production tenfold.
by Diana Lewis.
S.M.
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Zhang, Jing. "Différents traitements de surface des fibres de carbone et leur influence sur les propriétés à l'interface dans les composites fibres de carbone/résine époxyde." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2012. http://www.theses.fr/2012ECAP0038/document.
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Les matériaux composites à base de fibres de carbone (CF) sont actuellement très utilises dans le domaine de l’aérospatiale, de la construction et du sport grâce à leurs excellentes propriétés mécaniques, une faible densité et une haute stabilité thermique. Les propriétés des composites dépendent fortement de la nature et de la qualité de l’interface fibre/matrice. Une bonne adhérence interfaciale permet un meilleur transfert de charge entre la matrice et les fibres. Les CFs sans traitement sont chimiquement inertes et présentent donc une faible adhérence vis-à-vis de la résine époxyde. Par ailleurs, les faibles propriétés transversales et interlaminaires limitent sensiblement la performance et la durée de vie des composites. Par conséquent, un type de renfort à base de fibres traitées est fortement souhaité pour améliorer les propriétés globales des composites, en particulier l'adhésion interfaciale entre les fibres et la matrice. Dans cette thèse, trois types de traitement de surface, l’ensimage, le traitement thermique et la croissance de nanotubes (CNTs), ont été appliqués aux CFs. En particulier, les CFs greffées de CNTs, se combinant avec les deux autres traitements, montrent la meilleure adhérence interfaciale avec la matrice époxyde. L’ensimage proposé peut améliorer la performance du CNT-CF hybride et minimiser les dommages aux fibres lors de la manipulation ultérieure tels que le transport et la préparation de composites. Tout d’abord, l’ensimage a été réalisé sur la surface des fibres par dépôt de résine époxyde en solution. L’ensimage permet de protéger les filaments au cours de la mise en oeuvre et favorise également la liaison fibre/matrice. Différentes formulations d’ensimage selon les proportions époxy/durcisseur ont été utilisées. La quantité d'ensimage déposée sur les fibres de carbone a été contrôlée en faisant varier la concentration de la solution d’ensimage. Ensuite, un traitement thermique, effectué sous un mélange de gaz à 600-750 oC, a permis de modifier la surface des CFs. L'influence de la composition du gaz, du temps de traitement et de la température sur les propriétés interfaciales des composites CFs/époxy a été systématiquement quantifiée. Enfin, des CNTs ont été greffés sur les CFs par une méthode de dépôt chimique en phase vapeur en continu afin d’obtenir un nouveau type de renfort hybride multi-échelle. Les CNTs greffés permettent d’augmenter la surface de contact et d’améliorer l’accrochage mécanique de la fibre avec la résine. De plus, ils pourraient améliorer la résistance au délaminage, les propriétés électriques et thermiques des composites. Les CFs greffées de CNTs de différentes morphologies et densités ont été produites en faisant varier les conditions de croissance. Après le traitement de surface, les essais de fragmentation ont été menés afin d’évaluer la résistance au cisaillement interfacial (IFSS) des composites CFs/époxy. Par rapport aux fibres vierges, l’ensimage et le traitement thermique ont contribué à une augmentation de l'IFSS de 35% et de 75%, respectivement. L'adhésion interfaciale entre la matrice époxyde et les fibres greffées avec CNTs pourrait être adaptée en faisant varier la morphologie, la densité de nombre et la longueur de CNT. Les CFs greffées avec 2% en masse de CNTs (10nm de diamètre) ont entraîné une amélioration de l'IFSS de 60%. Un traitement thermique et un ensimage pourraient contribuer à une augmentation supplémentaire de 108%. Il convient de mentionner que la dégradation des fibres n’a pas été observée après les divers traitements précédemment évoqués. Les résultats de ces travaux pourraient mener au développement de ces techniques à plus grande échelle pour la conception de structures à base de composites CFs/époxyCarbon fiber (CF)-reinforced polymer composites are widely used in aerospace, construction and sporting goods due to their outstanding mechanical properties, light weight and high thermal stabilities. Their overall performance significantly depends on the quality of the fiber-matrix interface. A good interfacial adhesion provides efficient load transfer between matrix and fiber. Unfortunately, untreated CFs normally are extremely inert and have poor adhesion to resin matrices. Meanwhile, poor transverse and interlaminar properties greatly limit the composite performance and service life. Therefore, a new kind of fiber-based reinforcement is highly desired to improve the overall composite properties, especially the interfacial adhesion between fiber and matrix. In this thesis, three kinds of surface treatment, including sizing, heat treatment and carbon nanotube (CNT) growth, were applied to CFs. In particular, CFs grafted with CNTs, combining with the other two treatments demonstrate superior interfacial adhesion to the tested epoxy matrix. The proposed epoxy sizing can improve the CNT-CF hybrid performance and prevent fiber damage during the subsequent handling such as transport and composite preparation. Firstly, epoxy-based sizing was applied onto the CF surface by the deposition from polymer solutions. Sizing could not only protect the carbon fiber surface from damage during processing but also improve their wettability to polymer matrix. A detailed study was conducted on the influence of the ratio of epoxy and amine curing agent in the sizing formulation. The sizing level on the fiber surface was controlled by varying the concentration of polymer solutions. Secondly, heat treatment in a gas mixture at 600-750 oC was used to modify the carbon fiber surface. The effect of gas mixture composition, treatment time and temperature on the interface was evaluated systematically. Thirdly, CNTs were in-situ grafted on the carbon fiber surface by a continuous chemical vapour deposition (CVD) process to obtain hierarchical reinforcement structures. These hybrid structures have the potential to improve the interfacial strength of fiber/epoxy composites due to the increased lateral support of the load-bearing fibers. Meanwhile, the CNT reinforcement could improve the composite delamination resistance, electrical and thermal properties. The CF grown with CNTs of different morphologies and densities were produced by varying CVD conditions. After the surface treatment, single fiber fragmentation test was used to assess the interfacial shear strength (IFSS) of carbon fiber/epoxy composites. Compared with the as-received CFs, the epoxy sizing and the heat treatment contributed to an improvement in IFSS of up to 35% and 75%, respectively. The interfacial adhesion between epoxy matrix and CNT-grafted fibers could be tailored by varying the CNT morphology, number density and length. The CFs grafted with 2 wt% CNTs of 10 nm in diameter resulted in an improvement in IFSS of around 60%. A further heat treatment and epoxy sizing could contribute to an additional increase of 108%. It’s worth to mention that no significant strength degradation of the fibers was observed after the surface treatments. This work could support the development of large-scale approach to CF surface treatment, and throw light on the design of structurally efficient CF/epoxy composites
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Liu, Yaodong. "Stabilization and carbonization studies of polyacrylonitrile /carbon nanotube composite fibers." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42933.
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Carbon fibers contain more than 90 wt. % carbon. They have low density, high specific strength and modulus, and good temperature and chemical resistance. Therefore, they are important candidate as reinforcement materials. Carbon fiber is made by pyrolysing precursor polymers. Polyacrylonitrile (PAN) which has been used as precursor to produce high strength carbon fiber is used as precursor in this study. The theoretical tensile strength of carbon fibers can reach over 100 GPa. Currently, the best commercial carbon fibers reach only 7.5 GPa. To make good quality carbon fiber and to narrow the gap between theoretical values and currently achieved experimental properties, the entire manufacturing process including fiber spinning, stabilization and carbonization, needs to be improved optimized. In this dissertation, the stabilization processes of gel-spun PAN/carbon nanotubes (CNTs) composite fibers are studied.
PAN/CNT (1 wt. % CNT) composite fibers are spun by dry-jet gel-spinning. Three types of CNTs with different number of walls and varying catalyst content are used as additives. The effect of different types of CNTs on the properties of the stabilized fibers was compared. It is found that the CNTs with the highest surface area shows the best reinforcement efficiency on the tensile modulus, and reduces the formation of β-amino nitrile. The residual catalyst in the range of 1 to 4 wt. % shows little effect on the mechanical properties of the stabilized fibers.
Stabilization involves complex chemical reactions, including cyclization, oxidation, dehydration, and cross-linking. These complex reactions are separated by using different gas environments during stabilization. The cross-linking reaction has the highest activation energy among all stabilization reactions, and requires a temperature higher than 300 DegC to be completed. The effect of applied tension on the stabilized fiber properties are investigated, and it is found that higher tension leads to better properties for the stabilized fiber, including higher Young's modulus, higher orientation, less formation of β-amino nitrile, and less shrinkage.
The relationship between stabilization conditions and the mechanical properties of the carbonized fiber is investigated, and the methods to identify optimum stabilization conditions are proposed. It is observed that the highest tension should be applied during both stabilization and carbonization, and the mechanical properties of the resulting carbon fibers are increased if fibers are further stabilized at a temperature of ~ 320 DegC to improve the cross-linking degree as compared with the fibers only stabilized at 255 DegC. The optimum stabilization time depends on both the stabilization temperature and on the applied tension. A new characterization method by monitoring the dynamic mechanical properties, while stabilization is in progress is used to narrow down the range of the optimum stabilization time. Also, the effect of carbonization temperature on the ultimate carbon fiber properties is studied in the batch process carbonization. Preliminary studies are carried out to find the relationship between the structure and properties of precursor fibers and the tensile strength of carbon fibers, including mechanical properties and co-monomers of precursor fibers.
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Kuriger, Rex J. "Improved thermoplastic composite by alignment of vapor grown carbon fiber." Ohio : Ohio University, 2000. http://www.ohiolink.edu/etd/view.cgi?ohiou1179254413.
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Xu, Wenjun. "Carbon material based microelectromechanical system (MEMS): fabrication and devices." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39554.
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This PhD dissertation presents the exploration and development of two carbon materials, carbon nanotubes (CNTs) and carbon fiber (CF), as either key functional components or unconventional substrates for a variety of MEMS applications. Their performances in three different types of MEMS devices, namely, strain/stress sensors, vibration-powered generators and fiber solar cells, were evaluated and the working mechanisms of these two non-traditional materials in these systems were discussed. The work may potentially enable the development of new types of carbon-MEMS devices.
Firstly, a MEMS-assisted electrophoretic deposition (EPD) technique was developed, aiming to achieve controlled integration of CNT into both conventional and flexible MEMS systems. Selective deposition of electrically charged CNTs onto desired locations was realized in the EPD process through patterning of electric field lines created by the microelectrodes fabricated using MEMS techniques. A variety of 2-D and 3-D micropatterns of CNTs with controllable thickness and morphology have been successfully achieved in both rigid and elastic systems at room temperature with relatively high throughput. Studies also showed that high surface hydrophobicity of the non-conductive regions in microstructures was critical to accomplish well-defined selective micropatterning of CNTs through this strategy.
A patterned PDMS/CNT nanocomposite was then fabricated through the aforementioned approach, and was incorporated, investigated and validated in elastic force/strain microsensors. The gauge factor of the sensor exhibited a strong dependence on both the initial resistance of the device and the applied strain. Detailed analysis of the data suggests that the piezoresistive effect of this specially constructed bi-layer composite could be three folds, and the sensing mechanism may vary when physical properties of the CNT network embedded in the polymer matrix alter.
The feasibility of the PDSM/CNT nanocomposite serving as an elastic electret was further explored. The nanocomposite composed of these two non-traditional electret materials exhibited electret characteristics with reasonable charge storage stability. The power generation capacity of the corona-charged nanocomposite has been characterized and successfully demonstrated in both a ball drop experiment and the cyclic mechanical load experiments.
Lastly, in an effort to develop carbon-material-based substrates for MEMS applications, a carbon fiber-based poly-Si solar cell was designed, fabricated and investigated. This fiber-type photovoltaics (PV) takes advantage of the excellent thermal stability, electrical conductivity and spatial format of the CF, which allows CF to serve as both the building block and the electrode in the PV configuration. The photovoltaic effects of the fiber PV were demonstrated with an open-circuit voltage of 0.14 V, a short-circuit current density of 1.7 mA/cm2, and output power density of 0.059mW/cm2. The issues of this system were discussed as well.
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Troulis, Emmanouil. "Effect of Z-Fiber® pinning on the mechanical properties of carbon fibre/epoxy composites." Thesis, Cranfield University, 2003. http://dspace.lib.cranfield.ac.uk/handle/1826/107.
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This study investigates the effects of Z-pinning on the delamination performance in opening and shear loading modes in woven fabric reinforced / epoxy composite materials, as well as the effects of friction between specimen crack faces and the Z-pin failure mechanisms involved in mode II delamination. Mode I and mode II delamination tests are carried out on Z-pinned unidirectional (UD) and woven laminates. Both UD and woven laminates exhibit enhanced delamination resistance and crack propagation stability through Z-pinning. The effects of various structural and Z-pin parameters on the mode I and mode II delamination behaviour are separately assessed. The 4ENF testing configuration is deemed as the appropriate mode II configuration for the testing of Z-pinned laminates. A new basic friction rig is used to measure the friction coefficient between crack faces in woven laminates. An additional friction effect attributed to fibre architecture is identified. A specially designed delamination specimen is used to overcome the difficulty of accurately measuring crack propagation in Z-pinned woven fabric materials and aid data reduction using the available analytical methods. The failure mechanisms involved in the mode II delamination of Z-pinned laminates have been investigated with the implementation of a new test. Z-pins fail under shear loading through a combination of resin crushing, laminate fibre breakage, pin shear, pin bending and pin pullout. The balance of the failure mechanisms is shown to be a function of the crack opening constraint, material type, stacking sequence, Z-pin angle and insertion depth to Z-pin diameter ratio. Z-pin and material parameters influencing Z-pinning quality are identified, categorised and quantified. The importance of controlling Z-pin insertion depth is underlined and updated manufacturing procedures are proposed. Partial pinning appears as an advantageous alternative. A reduction in in-plane stiffness and in-plane strength in UD and woven fabric composites is measured, whilst no significant change of in-plane shear stiffness of UD materials is observed. A reduction in the fibre volume fraction is the single most important parameter affecting the in-plane stiffness. The performance of a Z-pinned sub-structural component is investigated. Enhanced loading carrying capacity and damage tolerance is achieved through Z-pinning.
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Thammongkol, Vivan. "Electrostatic fluidized bed prepegging of carbon fiber with PEEK." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/10272.
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Daga, Vijay. "High temperature deformation of pan-based carbon fiber precursors." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/11185.
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Pintossi, Marco. "Carbon fiber reinforced composite suspensions for a solar vehicle." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20564/.
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Questa tesi si svolge nell’ambito di progettazione CAD e produzione di componenti per il settore dell’automotive in CFRP, in questo particolare caso, per un’auto elettrica a pannelli solari.
Il lavoro da me svolto, aperto con una panoramica generale sulle tecnologie a basse emissioni oggi disponibili, è stato fatto a seguito di un percorso personale divisibile in tre fasi principali iniziate nel 2018 con la collaborazione alla costruzione della vettura Emilia 4, con la quale l’Università ha preso parte all’ASC 2018, una gara tenutasi in America, che ci ha visti vincitori della categoria cruiser. Ed è proprio parlando di competizioni che entriamo nella seconda fase del mio percorso, che vede affiancarsi alla trasferta americana, la trasferta australiana del 2019 per competere nel BWSC.
La terza ed ultima fase di questo percorso, che temporalmente è avvenuta tra le due competizioni, è stata la progettazione di un componente di Emilia 4, i bracci delle sospensioni anteriori e posteriori, utilizzando la fibra di carbonio tramite la progettazione CAD 3D, sfruttando Ansys e Solidworks. Il lavoro di tesi si impegna quindi ad unire le competenze acquisite in aula con le nuove tecnologie nel campo dei materiali, usando come veicolo di comunicazione la programmazione CAD.
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Taddei, Edoardo. "Numerical simulations of Carbon Fiber ReinforcedPolymers under dynamic loading." Thesis, KTH, Lättkonstruktioner, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-228194.
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The ability to withstand dynamic loading represents an important design criteria for crucial applications such as those adopted in the automotive and aerospace industries. Numerical simulations can lead to a reduction of time and costs for designing composite structures by replacing testing campaigns that are performed in order to assess whether the design requirements of the structure are met. The present thesis deals with the development of a robust simulation methodology within the FE explicit commercial code PAM-CRASH in order to predict the damage behaviour of Carbon Fiber Reinforced Polymers when loaded dynamically. The strain rate dependence of the carbon/epoxy composite under study is identified and a material-characteristic strain rate model is developed starting from experimental data. A delay damage model based on a Continuum Damage Mechanics approach is used to predict the response of composite laminates under dynamic loading. The simulation methodology is validated against experimental data from a patch to a coupon level by using solid elements to model the plies of the laminate. A dynamic three-point bending simulation is performed at the sub-component level by modelling the composite structure through the use of solid elements for the plies and cohesive elements for the interfaces between them. Rather good agreement is found in terms of stiffness and strength between the results from the numerical simulations and those obtained from the experimental tests. Limitations are identified in the sensitivity of the strain rate model to the damage limits set to stop the scaling of the lamina elastic moduli and in severe dynamic effects, e.g. stress waves, which affected the simulations at high strain rates.
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Bo-Huei, Ke, and 柯柏輝. "Evaluation of modified waste carbon fiber to activate carbon fiber." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/66984481727139599371.
Full textAbstract:
碩士雲林科技大學
環境與安全工程系碩士班
97
This research carried out to modify waste carbon fiber with acid (sulfuric acid) and oxidant (potassium permanganate), in order to increase the functional groups onto waste carbon fiber to activate carbon fiber and to adsorb aqueous reactive dyes. Before and after the modified process, the characteristic analysis includes surface area, scanning electron microscope (SEM), and Fourier Transform Infrared Spectrometer (FTIR). The adsorption analysis includes adsorption pH, time, and temperatures effect. The results indicated that there was only little change on the surface area of modified waste carbon fiber and surface was comparatively coarse in SEM. However, in FTIR, the results revealed that the modified waste carbon fiber increased the carboxylic, carbonyl, phenolic, and cyanogen groups. Because original carbon fiber was made by polyacrylonitrile, the increase of cyanogen groups proved the efficiency of modified process. In addition, the experimental adsorption results revealed that original waste carbon fiber showed almost no adsorption ability but modified waste carbon fiber becomed activate carbon fiber showed adsorption ability was 12.25 mg/g and 8.25 mg/g under pH 2 and 4 within 60 minutes then was close to the saturation. However, as pH increased to more than 6, the absorption ability decreased. Because carboxylic, carbonyl, phenolic groups of modified waste carbon fiber enhanced the absorption ability, the result verified that the effective modified process becomed waste carbon to activate carbon fiber. But the ability was limited due to the small surface area of modified waste carbon fiber. The experimental results in different temperatures indicated that absorption ability was better slightly at low temperature than at high temperature, but the difference was slight. Although waste carbon fiber existed its own structure to cause that the activate carbon fiber did not change much in physico-chemical properties after modified process, the activate carbon fiber still showed the adsorption ability. Base on the results, this research suggested that it should alter other methods to modify waste carbon fiber, such as increasing reactive temperature and time, using microwave for heating, increasing acidic and oxidizing concentration and so on. Therefore, it might promote the growth of functional groups, enhance the surface area and substantially increase the efficiency of absorption.
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Huang, Wei-Xiang, and 黃韋翔. "Dynamic compressive response of carbon fiber composite and carbon fiber corrugated sandwich panel." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/73zmv5.
Full textAbstract:
碩士國立高雄科技大學
機械工程系
107
Due to global warming and increasing fuel price, the cost of logistic and passenger transportation industries become more and more expensive. In transportation industry, vehicle weight is one of the most important design factors. The less vehicle weights the more goods/passengers it can carry. In order to achieve this goal, new materials that are lighter and stronger than conventional materials must be developed. Composite materials have been heavily utilized in transportation industries due to their light weight and high strength. In order to further improve fuel economy, various sandwich structures are being tested. In this study, dynamic compression tests and quasi-static compression tests are performed on carbon fiber, carbon fiber/ABS corrugated sandwich composites, carbon fiber/ABS honeycomb sandwich composites, and carbon fiber/ABS mesh sandwich composites. The energy absorptions and specific energy absorptions of honeycomb and mesh sandwich composites are higher than those of carbon fiber, which show potentials to be utilized in dynamic energy absorbing applications.