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Sample records for 18-inch carbon fiber

  1. Twelve Years on the Palomar 18-Inch Schmidt

    NASA Astrophysics Data System (ADS)

    Shoemaker, Carolyn S.

    1996-02-01

    The Palomar Asteroid and Comet Survey (PACS), which ended in December, 1994, after acquiring approximately 26,000 films on the 18-inch Schmidt telescope at Palomar Observatory, discovered 44 new near-Earth asteroids, 67 Mars crossers, 47 Jupiter Trojans, and many other asteroids of unusual motion. Also found were 33 new comets, of which 16 are periodic. The discoveries of the PACS have provided a basis for estimating the current rate of impact cratering on Earth as well as on other solid bodies of our solar system. The discovery in the program of Comet P/Shoemaker-Levy 9 provided to the world a graphic illustration of the fact that interplanetary wanderers do, indeed, collide with planets.

  2. Boeing 18-Inch Fan Rig Broadband Noise Test

    NASA Technical Reports Server (NTRS)

    Ganz, Ulrich W.; Joppa, Paul D.; Patten, Timothy J.; Scharpf, Daniel F.

    1998-01-01

    The purposes of the subject test were to identify and quantify the mechanisms by which fan broadband noise is produced, and to assess the validity of such theoretical models of those mechanisms as may be available. The test was conducted with the Boeing 18-inch fan rig in the Boeing Low-Speed Aeroacoustic Facility (LSAF). The rig was designed to be particularly clean and geometrically simple to facilitate theoretical modeling and to minimize sources of interfering noise. The inlet is cylindrical and is equipped with a boundary layer suction system. The fan is typical of modern high-by-pass ratio designs but is capable of operating with or without fan exit guide vanes (stators), and there is only a single flow stream. Fan loading and tip clearance are adjustable. Instrumentation included measurements of fan performance, the unsteady flow field incident on the fan and stators, and far-field and in-duct acoustic fields. The acoustic results were manipulated to estimate the noise generated by different sources. Significant fan broadband noise was found to come from the rotor self-noise as measured with clean inflow and no boundary layer. The rotor tip clearance affected rotor self-noise somewhat. The interaction of the rotor with inlet boundary layer turbulence is also a significant source, and is strongly affected by rotor tip clearance. High level noise can be generated by a high-order nonuniform rotating at a fraction of the fan speed, at least when tip clearance and loading are both large. Stator-generated noise is the loudest of the significant sources, by a small margin, at least on this rig. Stator noise is significantly affected by propagation through the fan.

  3. Orthopedic stretcher with average-sized person can pass through 18-inch opening

    NASA Technical Reports Server (NTRS)

    Lothschuetz, F. X.

    1966-01-01

    Modified Robinson stretcher for vertical lifting and carrying, will pass through an opening 18 inches in diameter, while containing a person of average height and weight. A subject 6 feet tall and weighing 200 pounds was lowered and raised out of an 18 inch diameter opening in a tank to test the stretcher.

  4. Nanotube composite carbon fibers

    NASA Astrophysics Data System (ADS)

    Andrews, R.; Jacques, D.; Rao, A. M.; Rantell, T.; Derbyshire, F.; Chen, Y.; Chen, J.; Haddon, R. C.

    1999-08-01

    Single walled carbon nanotubes (SWNTs) were dispersed in isotropic petroleum pitch matrices to form nanotube composite carbon fibers with enhanced mechanical and electrical properties. We find that the tensile strength, modulus, and electrical conductivity of a pitch composite fiber with 5 wt % loading of purified SWNTs are enhanced by ˜90%, ˜150%, and 340% respectively, as compared to the corresponding values in unmodified isotropic pitch fibers. These results serve to highlight the potential that exits for developing a spectrum of material properties through the selection of the matrix, nanotube dispersion, alignment, and interfacial bonding.

  5. Carbon Fiber Risk Analysis. [conference

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The scope and status of the effort to assess the risks associated with the accidental release of carbon/graphite fibers from civil aircraft is presented. Vulnerability of electrical and electronic equipment to carbon fibers, dispersal of carbon fibers, effectiveness of filtering systems, impact of fiber induced failures, and risk methodology are among the topics covered.

  6. Carbon Fibers Conductivity Studies

    NASA Technical Reports Server (NTRS)

    Yang, C. Y.; Butkus, A. M.

    1980-01-01

    In an attempt to understand the process of electrical conduction in polyacrylonitrile (PAN)-based carbon fibers, calculations were carried out on cluster models of the fiber consisting of carbon, nitrogen, and hydrogen atoms using the modified intermediate neglect of differential overlap (MINDO) molecular orbital (MO) method. The models were developed based on the assumption that PAN carbon fibers obtained with heat treatment temperatures (HTT) below 1000 C retain nitrogen in a graphite-like lattice. For clusters modeling an edge nitrogen site, analysis of the occupied MO's indicated an electron distribution similar to that of graphite. A similar analysis for the somewhat less stable interior nitrogen site revealed a partially localized II electron distribution around the nitrogen atom. The differences in bonding trends and structural stability between edge and interior nitrogen clusters led to a two-step process proposed for nitrogen evolution with increasing HTT.

  7. Boron nitride converted carbon fiber

    DOEpatents

    Rousseas, Michael; Mickelson, William; Zettl, Alexander K.

    2016-04-05

    This disclosure provides systems, methods, and apparatus related to boron nitride converted carbon fiber. In one aspect, a method may include the operations of providing boron oxide and carbon fiber, heating the boron oxide to melt the boron oxide and heating the carbon fiber, mixing a nitrogen-containing gas with boron oxide vapor from molten boron oxide, and converting at least a portion of the carbon fiber to boron nitride.

  8. Carbon Fiber Composites

    NASA Technical Reports Server (NTRS)

    1997-01-01

    HyComp(R), Inc. development a line of high temperature carbon fiber composite products to solve wear problems in the harsh environment of steel and aluminum mills. WearComp(R), self-lubricating composite wear liners and bushings, combines carbon graphite fibers with a polyimide binder. The binder, in conjunction with the fibers, provides the slippery surface, one that demands no lubrication, yet wears at a very slow rate. WearComp(R) typically lasts six to ten times longer than aluminum bronze. Unlike bronze, WearComp polishes the same surface and imparts a self-lube film for years of service. It is designed for continuous operation at temperatures of 550 degrees Fahrenheit and can operate under high compressive loads.

  9. Method of carbonizing polyacrylonitrile fibers

    NASA Technical Reports Server (NTRS)

    Cagliostro, D. E.; Lerner, N. R. (Inventor)

    1983-01-01

    This invention relates to a method of carbonizing polyacrylonitrile fibers by exposing the fibers at an elevated temperature to an oxidizing atmosphere; then exposing the oxidized fibers to an atmosphere of an inert gas such as nitrogen containing a carbonaceous material such as acetylene. The fibers are preferably treated with an organic compound, for example benzoic acid, before the exposure to an oxidizing atmosphere. The invention also relates to the resulting fibers. The treated fibers have enhanced tensile strength.

  10. Method for the preparation of carbon fiber from polyolefin fiber precursor, and carbon fibers made thereby

    DOEpatents

    Naskar, Amit Kumar; Hunt, Marcus Andrew; Saito, Tomonori

    2015-08-04

    Methods for the preparation of carbon fiber from polyolefin fiber precursor, wherein the polyolefin fiber precursor is partially sulfonated and then carbonized to produce carbon fiber. Methods for producing hollow carbon fibers, wherein the hollow core is circular- or complex-shaped, are also described. Methods for producing carbon fibers possessing a circular- or complex-shaped outer surface, which may be solid or hollow, are also described.

  11. Multimetallic Electrodeposition on Carbon Fibers

    NASA Astrophysics Data System (ADS)

    Böttger-Hiller, F.; Kleiber, J.; Böttger, T.; Lampke, T.

    2016-03-01

    Efficient lightweight design requires intelligent materials that meet versatile functions. One approach is to extend the range of properties of carbon fiber reinforced plastics (CFRP) by plating the fiber component. Electroplating leads to metalized layers on carbon fibers. Herein only cyanide-free electrolytes where used. Until now dendrite-free layers were only obtained using current densities below 1.0 A dm-2. In this work, dendrite-free tin and copper coatings were achieved by pre-metalizing the carbon fiber substrates. Furthermore, applying a combination of two metals with different sized thermal expansion coefficient lead to a bimetallic coating on carbon fiber rovings, which show an actuatory effect.

  12. Stronger Carbon Fibers for Reinforced Plastics

    NASA Technical Reports Server (NTRS)

    Cagliostro, D. E.; Lerner, N. R.

    1983-01-01

    Process makes fibers 70 percent stronger at lower carbonization temperature. Stronger carbon fibers result from benzoic acid pretreatment and addition of acetylene to nitrogen carbonizing atmosphere. New process also makes carbon fibers of higher electrical resistance -- an important safety consideration.

  13. Carbon Fiber Biocompatibility for Implants

    PubMed Central

    Petersen, Richard

    2016-01-01

    Carbon fibers have multiple potential advantages in developing high-strength biomaterials with a density close to bone for better stress transfer and electrical properties that enhance tissue formation. As a breakthrough example in biomaterials, a 1.5 mm diameter bisphenol-epoxy/carbon-fiber-reinforced composite rod was compared for two weeks in a rat tibia model with a similar 1.5 mm diameter titanium-6-4 alloy screw manufactured to retain bone implants. Results showed that carbon-fiber-reinforced composite stimulated osseointegration inside the tibia bone marrow measured as percent bone area (PBA) to a great extent when compared to the titanium-6-4 alloy at statistically significant levels. PBA increased significantly with the carbon-fiber composite over the titanium-6-4 alloy for distances from the implant surfaces of 0.1 mm at 77.7% vs. 19.3% (p < 10−8) and 0.8 mm at 41.6% vs. 19.5% (p < 10−4), respectively. The review focuses on carbon fiber properties that increased PBA for enhanced implant osseointegration. Carbon fibers acting as polymer coated electrically conducting micro-biocircuits appear to provide a biocompatible semi-antioxidant property to remove damaging electron free radicals from the surrounding implant surface. Further, carbon fibers by removing excess electrons produced from the cellular mitochondrial electron transport chain during periods of hypoxia perhaps stimulate bone cell recruitment by free-radical chemotactic influences. In addition, well-studied bioorganic cell actin carbon fiber growth would appear to interface in close contact with the carbon-fiber-reinforced composite implant. Resulting subsequent actin carbon fiber/implant carbon fiber contacts then could help in discharging the electron biological overloads through electrochemical gradients to lower negative charges and lower concentration. PMID:26966555

  14. Gasifiable carbon-graphite fibers

    NASA Technical Reports Server (NTRS)

    Humphrey, Marshall F. (Inventor); Ramohalli, Kumar N. R. (Inventor); Dowler, Warren L. (Inventor)

    1982-01-01

    Fine, carbon-graphite fibers do not combust during the combustion of a composite and are expelled into the air as fine conductive particles. Coating of the fibers with a salt of a metal having a work function below 4.2 eV such as an alkaline earth metal salt, e.g., calcium acetate, catalytically enhances combustion of the fibers at temperatures below 1000.degree. C. such that the fibers self-support combustion and burn to produce a non-conductive ash. Fire-polishing the fibers before application of the coating is desirable to remove sizing to expose the carbon surface to the catalyst.

  15. Source of released carbon fibers

    NASA Technical Reports Server (NTRS)

    Bell, V. L.

    1979-01-01

    The potential for the release of carbon fibers from aircraft crashes/fires is addressed. Simulation of the conditions of aircraft crash fires in order to predict the quantities and forms of fibrous materials which might be released from civilian aircraft crashes/fires is considered. Figures are presented which describe some typical fiber release test activities together with some very preliminary results of those activities. The state of the art of carbon fiber release is summarized as well as some of the uncertainties concerning accidental fiber release.

  16. Development of a 6 x 18 inch rheology tunnel for experimental fluid dynamics investigation.

    PubMed

    Miklosovic, D S; Gregorek, G M; Smith, W A; Golding, L A

    1997-01-01

    The Ohio State University (OSU) and the Cleveland Clinic Foundation (CCF) developed a 6 x 18 inch low velocity Rheologic Research Tunnel to do flow visualization and other experimental fluid studies, particularly on scaled-up models of cardiovascular devices, such as the CCF's Innovative Ventricular Assist System. The large test section (TS) permits detailed data to be obtained that would be inaccessible with a smaller test prototype. A particular feature of the OSU-CCF program is the use of a non-Newtonian blood analog (NNBA), so the effect of the shear-thinning behavior of blood on the local development of separation, stagnation, and flow patterns can be studied. The TS can simulate a pressure driven slit flow of 6 x 18 in., or the external flow around a vane or blade having an aspect ratio of 1. Maximum pressure is 8.5 psig, while the maximum velocity is 21.7 in/sec. The fluid supply tank has a capacity of 500 gal of NNBA and, with its associated filtration and circulation systems, can be adapted to studies of large transparent models better studied outside the TS. Using 2 pumps, flow rates of 98-610 gal/min can be provided. Instrumentation includes thermistors, a 48 port pressure scanner with pressure transducers, a data acquisition system, and a digital video camera. Dye and hydrogen bubble systems have been developed. Development of such a facility presents problems not encountered in more typical water tables or wind tunnels. These include fundamental issues such as providing a uniform flowfield; practical issues with respect to priming, operating, and obtaining data from the system; and safety considerations. For the very large volume of NNBA, a xanthan gum solution is used, whose shear-thinning behavior depends not only on concentration, but also on age and prior shear history. The lessons learned are presented, permitting others to efficiently develop systems suitable to their testing needs. PMID:9360120

  17. Coating Carbon Fibers With Platinum

    NASA Technical Reports Server (NTRS)

    Effinger, Michael R.; Duncan, Peter; Coupland, Duncan; Rigali, Mark J.

    2007-01-01

    A process for coating carbon fibers with platinum has been developed. The process may also be adaptable to coating carbon fibers with other noble and refractory metals, including rhenium and iridium. The coated carbon fibers would be used as ingredients of matrix/fiber composite materials that would resist oxidation at high temperatures. The metal coats would contribute to oxidation resistance by keeping atmospheric oxygen away from fibers when cracks form in the matrices. Other processes that have been used to coat carbon fibers with metals have significant disadvantages: Metal-vapor deposition processes yield coats that are nonuniform along both the lengths and the circumferences of the fibers. The electrical resistivities of carbon fibers are too high to be compatible with electrolytic processes. Metal/organic vapor deposition entails the use of expensive starting materials, it may be necessary to use a furnace, and the starting materials and/or materials generated in the process may be hazardous. The present process does not have these disadvantages. It yields uniform, nonporous coats and is relatively inexpensive. The process can be summarized as one of pretreatment followed by electroless deposition. The process consists of the following steps: The surfaces of the fiber are activated by deposition of palladium crystallites from a solution. The surface-activated fibers are immersed in a solution that contains platinum. A reducing agent is used to supply electrons to effect a chemical reduction in situ. The chemical reduction displaces the platinum from the solution. The displaced platinum becomes deposited on the fibers. Each platinum atom that has been deposited acts as a catalytic site for the deposition of another platinum atom. Hence, the deposition process can also be characterized as autocatalytic. The thickness of the deposited metal can be tailored via the duration of immersion and the chemical activity of the solution.

  18. Carbon Fiber Risk Analysis: Conclusions

    NASA Technical Reports Server (NTRS)

    Huston, R. J.

    1979-01-01

    It was concluded that preliminary estimates indicate that the public risk due to accidental release of carbon fiber from air transport aircraft is small. It was also concluded that further work is required to increase confidence in these estimates.

  19. Compressive strength of carbon fibers

    SciTech Connect

    Prandy, J.M. ); Hahn, H.T. )

    1991-01-01

    Most composites are weaker in compression than in tension, which is due to the poor compressive strength of the load bearing fibers. The present paper discusses the compressive strengths and failure modes of 11 different carbon fibers: PAN-AS1, AS4, IM6, IM7, T700, T300, GY-30, pitch-75, ultra high modulus (UHM), high modulus (HM), and high strength (HS). The compressive strength was determined by embedding a fiber bundle in a transparent epoxy matrix and testing in compression. The resin allows for the containment and observation of failure during and after testing while also providing lateral support to the fibers. Scanning electron microscopy (SEM) was used to determine the global failure modes of the fibers.

  20. Interfacial adhesion of carbon fibers

    NASA Technical Reports Server (NTRS)

    Bascom, Willard D.

    1987-01-01

    Relative adhesion strengths between AS4, AS1, and XAS carbon fibers and thermoplastic polymers were determined using the embedded single filament test. Polymers studied included polycarbonate, polyphenylene oxide, polyetherimide, polysulfone, polyphenylene oxide blends with polystyrene, and polycarbonate blends with a polycarbonate polysiloxane block copolymer. Fiber surface treatments and sizings improved adhesion somewhat, but adhesion remained well below levels obtained with epoxy matrices. An explanation for the differences between the Hercules and Grafil fibers was sought using X ray photon spectroscopy, wetting, scanning electron microscopy and thermal desorption analysis.

  1. Thermoplastic coating of carbon fibers

    NASA Technical Reports Server (NTRS)

    Edie, D. D.; Lickfield, G. C.; Allen, L. E.; Mccollum, J. R.

    1989-01-01

    A continuous powder coating system was developed for coating carbon fiber with LaRC-TPI (Langley Research Center-Thermoplastic Polyimide), a high-temperature thermoplastic polymide invented by NASA-Langley. The coating line developed used a pneumatic fiber spreader to separate the individual fibers. The polymer was applied within a recirculating powder coating chamber then melted using a combination of direct electrical resistance and convective heating to make it adhere to the fiber tow. The tension and speed of the line were controlled with a dancer arm and an electrically driven fiber wind-up and wind-off. The effects of heating during the coating process on the flexibility of the prepreg produced were investigated. The uniformity with which the fiber tow could be coated with polymer also was examined. Composite specimens were fabricated from the prepreg and tested to determine optimum process conditions. The study showed that a very uniform and flexible prepeg with up to 50 percent by volume polymer could be produced with this powder coating system. The coating line minimized powder loss and produced prepeg in lengths of up to 300 m. The fiber spreading was found to have a major effect on the coating uniformity and flexibility. Though test results showed low composite tensile strengths, analysis of fracture surfaces under scanning electron microscope indicated that fiber/matrix adhesion was adequate.

  2. Assessment of Carbon Fiber Electrical Effects

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The risks associated with the use of carbon fiber composites in civil aircraft are discussed along with the need for protection of civil aircraft equipment from fire-released carbon fibers. The size and number of carbon fibers released in civil aircraft crash fires, the downwind dissemination of the fibers, their penetration into buildings and equipment, and the vulnerability of electrical/electronic equipment to damage by the fibers are assessed.

  3. Carbon fiber study

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A coordinated Federal Government action plan for dealing with the potential problems arising from the increasing use of graphite fiber reinforced composite materials in both military and civilian applications is presented. The required dissemination of declassified information and an outline of government actions to minimize the social and economic consequences of proliferated composite materials applications were included.

  4. Thermoplastic-carbon fiber hybrid yarn

    NASA Technical Reports Server (NTRS)

    Ketterer, M. E.

    1984-01-01

    Efforts were directed to develop processing methods to make carbon fiber/thermoplastic fiber preforms that are easy to handle and drapeable, and to consolidate them into low void content laminates. The objectives were attained with the development of the hybrid yarn concept; whereby, thermoplastic fiber can be intimately intermixed with carbon fiber into a hybrid yarn. This was demonstrated with the intermixing of Celion 3000 with a Celanese liquid crystal polymer fiber, polybutylene terepthalate fiber, or polyetheretherketone fiber. The intermixing of the thermoplastic matrix fiber and the reinforcing carbon fiber gives a preform that can be easily fabricated into laminates with low void content. Mechanical properties of the laminates were not optimized; however, initial results indicated properties typical of a thermoplastic/carbon fiber composites prepared by more conventional methods.

  5. Carbon fiber internal pressure vessels

    NASA Technical Reports Server (NTRS)

    Simon, R. A.

    1973-01-01

    Internal pressure vessels were designed; the filament was wound of carbon fibers and epoxy resin and tested to burst. The fibers used were Thornel 400, Thornel 75, and Hercules HTS. Additional vessels with type A fiber were made. Polymeric linears were used, and all burst testing was done at room temperature. The objective was to produce vessels with the highest attainable PbV/W efficiencies. The type A vessels showed the highest average efficiency: 2.56 x 10 to the 6th power cm. Next highest efficiency was with Thornel 400 vessels: 2.21 x 10 to the 6th power cm. These values compare favorably with efficiency values from good quality S-glass vessels, but strains averaged 0.97% or less, which is less than 1/3 the strain of S-glass vessels.

  6. Carbon nanotube fiber spun from wetted ribbon

    SciTech Connect

    Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi

    2014-04-29

    A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

  7. Carbon fibers from SRC pitch

    DOEpatents

    Greskovich, Eugene J.; Givens, Edwin N.

    1981-01-01

    This invention relates to an improved method of manufacturing carbon fibers from a coal derived pitch. The improvement resides in the use of a solvent refined coal which has been hydrotreated and subjected to solvent extraction whereby the hetero atom content in the resulting product is less than 4.0% by weight and the softening point is between about 100.degree.-250.degree. F.

  8. Storing Fluorine In Graphitelike Carbon Fibers

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    1995-01-01

    Fluorine stored in graphite or graphitelike carbon fibers for later release and/or use in chemical reactions. Storage in carbon fibers eliminates difficulty and risk of using high-pressure tanks and pipes to hold corrosive gas. Storage in carbon fibers makes fluorine more readily accessible than does storage as constituent of metal fluoride. Carbon fibers heated to release stored fluorine, which draws away to vessel where reacts with material to be fluorinated, possibly at temperature other than release temperature. Alternatively, material to be fluorinated mixed or otherwise placed in contact with fibers and entire mass heated to or beyond release temperature.

  9. Interfacial Studies of Sized Carbon Fiber

    SciTech Connect

    Shahrul, S. N.; Hartini, M. N.; Hilmi, E. A.; Nizam, A.

    2010-03-11

    This study was performed to investigate the influence of sizing treatment on carbon fiber in respect of interfacial adhesion in composite materials, Epolam registered 2025. Fortafil unsized carbon fiber was used to performed the experiment. The fiber was commercially surface treated and it was a polyacrylonitrile based carbon fiber with 3000 filament per strand. Epicure registered 3370 was used as basic sizing chemical and dissolved in two types of solvent, ethanol and acetone for the comparison purpose. The single pull out test has been used to determine the influence of sizing on carbon fiber. The morphology of carbon fiber was observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The apparent interfacial strength IFSS values determined by pull out test for the Epicure registered 3370/ethanol sized carbon fiber pointed to a good interfacial behaviour compared to the Epicure registered 3370/acetone sized carbon fiber. The Epicure registered 3370/ethanol sizing agent was found to be effective in promoting adhesion because of the chemical reactions between the sizing and Epolam registered 2025 during the curing process. From this work, it showed that sized carbon fiber using Epicure registered 3370 with addition of ethanol give higher mechanical properties of carbon fiber in terms of shear strength and also provided a good adhesion between fiber and matrix compared to the sizing chemical that contain acetone as a solvent.

  10. Interfacial Studies of Sized Carbon Fiber

    NASA Astrophysics Data System (ADS)

    Shahrul, S. N.; Hartini, M. N.; Hilmi, E. A.; Nizam, A.

    2010-03-01

    This study was performed to investigate the influence of sizing treatment on carbon fiber in respect of interfacial adhesion in composite materials, Epolam® 2025. Fortafil unsized carbon fiber was used to performed the experiment. The fiber was commercially surface treated and it was a polyacrylonitrile based carbon fiber with 3000 filament per strand. Epicure® 3370 was used as basic sizing chemical and dissolved in two types of solvent, ethanol and acetone for the comparison purpose. The single pull out test has been used to determine the influence of sizing on carbon fiber. The morphology of carbon fiber was observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The apparent interfacial strength IFSS values determined by pull out test for the Epicure® 3370/ethanol sized carbon fiber pointed to a good interfacial behaviour compared to the Epicure® 3370/acetone sized carbon fiber. The Epicure® 3370/ethanol sizing agent was found to be effective in promoting adhesion because of the chemical reactions between the sizing and Epolam® 2025 during the curing process. From this work, it showed that sized carbon fiber using Epicure® 3370 with addition of ethanol give higher mechanical properties of carbon fiber in terms of shear strength and also provided a good adhesion between fiber and matrix compared to the sizing chemical that contain acetone as a solvent.

  11. A novel carbon fiber based porous carbon monolith

    SciTech Connect

    Burchell, T.D.; Klett, J.W.; Weaver, C.E.

    1995-06-01

    A novel porous carbon material based on carbon fibers has been developed. The material, when activated, develops a significant micro- or mesopore volume dependent upon the carbon fiber type utilized (isotropic pitch or polyacrylonitrile). The materials will find applications in the field of fluid separations or as a catalyst support. Here, the manufacture and characterization of our porous carbon monoliths are described. A novel adsorbent carbon composite material has been developed comprising carbon fibers and a binder. The material, called carbon fiber composite molecular sieve (CFCMS), was developed through a joint research program between Oak Ridge National Laboratory (ORNL) and the University of Kentucky, Center for Applied Energy Research (UKCAER).

  12. Carbon fiber manufacturing via plasma technology

    DOEpatents

    Paulauskas, Felix L.; Yarborough, Kenneth D.; Meek, Thomas T.

    2002-01-01

    The disclosed invention introduces a novel method of manufacturing carbon and/or graphite fibers that avoids the high costs associated with conventional carbonization processes. The method of the present invention avoids these costs by utilizing plasma technology in connection with electromagnetic radiation to produce carbon and/or graphite fibers from fully or partially stabilized carbon fiber precursors. In general, the stabilized or partially stabilized carbon fiber precursors are placed under slight tension, in an oxygen-free atmosphere, and carbonized using a plasma and electromagnetic radiation having a power input which is increased as the fibers become more carbonized and progress towards a final carbon or graphite product. In an additional step, the final carbon or graphite product may be surface treated with an oxygen-plasma treatment to enhance adhesion to matrix materials.

  13. High voltage spark carbon fiber detection system

    NASA Technical Reports Server (NTRS)

    Yang, L. C.

    1980-01-01

    The pulse discharge technique was used to determine the length and density of carbon fibers released from fiber composite materials during a fire or aircraft accident. Specifications are given for the system which uses the ability of a carbon fiber to initiate spark discharge across a high voltage biased grid to achieve accurate counting and sizing of fibers. The design of the system was optimized, and prototype hardware proved satisfactory in laboratory and field tests.

  14. Effects of heat treatment on carbon fibers

    NASA Technical Reports Server (NTRS)

    Brown, D. Kyle; Phillips, Wayne M.

    1990-01-01

    Commercially produced carbon fibers were heat treated to graphitization temperatures. The fibers were characterized for mechanical and physical properties, including density, D0002 spacing, strength, and modulus in both the 'as received' and heat treated conditions. Mechanical property changes were correlated with the physical property changes in the fibers.

  15. Photoconductivity of Activated Carbon Fibers

    DOE R&D Accomplishments Database

    Kuriyama, K.; Dresselhaus, M. S.

    1990-08-01

    The photoconductivity is measured on a high-surface-area disordered carbon material, namely activated carbon fibers, to investigate their electronic properties. Measurements of decay time, recombination kinetics and temperature dependence of the photoconductivity generally reflect the electronic properties of a material. The material studied in this paper is a highly disordered carbon derived from a phenolic precursor, having a huge specific surface area of 1000--2000m{sup 2}/g. Our preliminary thermopower measurements suggest that this carbon material is a p-type semiconductor with an amorphous-like microstructure. The intrinsic electrical conductivity, on the order of 20S/cm at room temperature, increases with increasing temperature in the range 30--290K. In contrast with the intrinsic conductivity, the photoconductivity in vacuum decreases with increasing temperature. The recombination kinetics changes from a monomolecular process at room temperature to a biomolecular process at low temperatures. The observed decay time of the photoconductivity is {approx equal}0.3sec. The magnitude of the photoconductive signal was reduced by a factor of ten when the sample was exposed to air. The intrinsic carrier density and the activation energy for conduction are estimated to be {approx equal}10{sup 21}/cm{sup 3} and {approx equal}20meV, respectively. The majority of the induced photocarriers and of the intrinsic carriers are trapped, resulting in the long decay time of the photoconductivity and the positive temperature dependence of the conductivity.

  16. High performance pitch-based carbon fiber

    SciTech Connect

    Tadokoro, Hiroyuki; Tsuji, Nobuyuki; Shibata, Hirotaka; Furuyama, Masatoshi

    1996-12-31

    The high performance pitch-based carbon fiber with smaller diameter, six micro in developed by Nippon Graphite Fiber Corporation. This fiber possesses high tensile modulus, high tensile strength, excellent yarn handle ability, low thermal expansion coefficient, and high thermal conductivity which make it an ideal material for space applications such as artificial satellites. Performance of this fiber as a reinforcement of composites was sufficient. With these characteristics, this pitch-based carbon fiber is expected to find wide variety of possible applications in space structures, industrial field, sporting goods and civil infrastructures.

  17. The transport properties of activated carbon fibers

    SciTech Connect

    di Vittorio, S.L. . Dept. of Materials Science and Engineering); Dresselhaus, M.S. . Dept. of Electrical Engineering and Computer Science Massachusetts Inst. of Tech., Cambridge, MA . Dept. of Physics); Endo, M. . Dept. of Electrical Engineering); Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons. 19 refs., 4 figs.

  18. The Transport Properties of Activated Carbon Fibers

    DOE R&D Accomplishments Database

    di Vittorio, S. L.; Dresselhaus, M. S.; Endo, M.; Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons.

  19. Carbon fiber behavior in an enclosed volume

    NASA Technical Reports Server (NTRS)

    Harvey, M. C.

    1979-01-01

    Tests were performed to evaluate the behavior of single carbon fibers existing in an enclosed space such as a room of a building. Three general phenomena were explored: the concentration decay rate of a fiber-charged room, the degree of uniform mixing of fibers within a room, and the effects of fibers being redisseminated off deposition surfaces within a room. The results were required in understanding the ratio of total indoor fiber exposure to total outdoor fiber exposure, a quantity essential to risk analysis. Results indicate that decay rate is predictable within acceptable limits and that homogeneous mixing can always be assumed. Some factors of redissemination are identified and effects discussed.

  20. Characterization of electrospun lignin based carbon fibers

    NASA Astrophysics Data System (ADS)

    Poursorkhabi, Vida; Mohanty, Amar; Misra, Manjusri

    2015-05-01

    The production of lignin fibers has been studied in order to replace the need for petroleum based precursors for carbon fiber production. In addition to its positive environmental effects, it also benefits the economics of the industries which cannot take advantage of carbon fiber properties because of their high price. A large amount of lignin is annually produced as the byproduct of paper and growing cellulosic ethanol industry. Therefore, finding high value applications for this low cost, highly available material is getting more attention. Lignin is a biopolymer making about 15 - 30 % of the plant cell walls and has a high carbon yield upon carbonization. However, its processing is challenging due to its low molecular weight and also variations based on its origin and the method of separation from cellulose. In this study, alkali solutions of organosolv lignin with less than 1 wt/v% of poly (ethylene oxide) and two types of lignin (hardwood and softwood) were electrospun followed by carbonization. Different heating programs for carbonization were tested. The carbonized fibers had a smooth surface with an average diameter of less than 5 µm and the diameter could be controlled by the carbonization process and lignin type. Scanning electron microscopy (SEM) was used to study morphology of the fibers before and after carbonization. Thermal conductivity of a sample with amorphous carbon was 2.31 W/m.K. The electrospun lignin carbon fibers potentially have a large range of application such as in energy storage devices and water or gas purification systems.

  1. Surface analyses of carbon fibers produced from polyacrylonitrile fibers at low carbonization temperatures

    NASA Technical Reports Server (NTRS)

    Cagliostro, D. E.

    1983-01-01

    A process for producing carbon fibers from polyacrylonitrile at low carbonization temperatures was studied. The bulk and surface properties of fibers obtained after reaction with benzoic acid, air and carbonizing in nitrogen or a dilute acetylene atmosphere are discussed. All fiber products had different surface and internal compositions. Samples produced at temperatures up to 950 C and carbonized in nitrogen contained substantial quantities of nitrogen and oxygen at the surface. During carbonization, the surface nitrogen converted into two new forms, possibly nitrile and an azo or a new carbon-nitrogen bond. Samples carbonized in acetylene contained a carbon-rich surface stable to oxidation.

  2. FIBER ORIENTATION IN INJECTION MOLDED LONG CARBON FIBER THERMOPLASTIC COMPOSITES

    SciTech Connect

    Wang, Jin; Nguyen, Ba Nghiep; Mathur, Raj N.; Sharma, Bhisham; Sangid, Michael D.; Costa, Franco; Jin, Xiaoshi; Tucker III, Charles L.; Fifield, Leonard S.

    2015-03-23

    A set of edge-gated and center-gated plaques were injection molded with long carbon fiber-reinforced thermoplastic composites, and the fiber orientation was measured at different locations of the plaques. Autodesk Simulation Moldflow Insight (ASMI) software was used to simulate the injection molding of these plaques and to predict the fiber orientation, using the anisotropic rotary diffusion and the reduced strain closure models. The phenomenological parameters of the orientation models were carefully identified by fitting to the measured orientation data. The fiber orientation predictions show very good agreement with the experimental data.

  3. Heat Treated Carbon Fiber Material Selection Database

    NASA Technical Reports Server (NTRS)

    Effinger, M.; Patel, B.; Koenig, J.

    2008-01-01

    Carbon fibers are used in a variety high temperature applications and materials. However, one limiting factor in their transition into additional applications is an understanding of their functional properties during component processing and function. The requirements on the fibers are governed by the nature of the materials and the environments in which they will be used. The current carbon fiber vendor literature is geared toward the polymeric composite industry and not the ceramic composite industry. Thus, selection of carbon fibers is difficult, since their properties change as a function of heat treatment, processing or component operational temperature, which ever is greatest. To enable proper decisions to be made, a program was established wherein multiple fibers were selected and heat treated at different temperatures. The fibers were then examined for their physical and mechanical properties which are reported herein.

  4. Wettability of a Single Carbon Fiber.

    PubMed

    Qiu, Si; Fuentes, Carlos A; Zhang, Dongxing; Van Vuure, Aart Willem; Seveno, David

    2016-09-27

    Wettability as determined from contact angle measurements is a suitable parameter for characterizing the physical bonding of a polymer matrix and reinforcing fibers, but it is very challenging to measure the capillary force exerted by a probe liquid on a fiber accurately for very fine fibers such as single carbon fibers. Herein, we propose an innovative method for measuring dynamic contact angles with a tensiometer, considering both the intrinsic variability of the carbon fiber diameter and the extremely small amplitude of the capillary forces, allowing the measurement of reliable dynamic contact angles over a large range of contact line velocities. The analysis of the contact angle dynamics by the molecular-kinetic theory permits us to check the relevancy of the measured contact angles and to obtain the static contact angle value, improving the prospect of employing tensiometry to better understand the wetting behavior of carbon fibers.

  5. Method of Manufacturing Carbon Fiber Reinforced Carbon Composite Valves

    NASA Technical Reports Server (NTRS)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor)

    1998-01-01

    A method for forming a carbon composite valve for internal combustion engines is discussed. The process includes the steps of braiding carbon fiber into a rope thereby forming a cylindrically shaped valve stem portion and continuing to braid said fiber while introducing into the braiding carbon fiber rope a carbon matrix plug having an outer surface in a net shape of a valve head thereby forming a valve head portion. The said carbon matrix plug acting as a mandrel over which said carbon fiber rope is braided, said carbon fiber rope and carbon matrix plug forming a valve head portion suitable for mating with a valve seat; cutting said braided carbon valve stem portion at one end to form a valve tip and cutting said braided carbon fiber after said valve head portion to form a valve face and thus provide a composite valve preform; and densifying said preform by embedding the braided carbon in a matrix of carbon to convert said valve stem portion to a valve stem and said valve head portion to a valve head thereby providing said composite valve.

  6. High electrical resistivity carbon/graphite fibers

    NASA Technical Reports Server (NTRS)

    Vogel, F. L.; Forsman, W. C.

    1980-01-01

    Carbon/graphite fibers were chemically oxidized in the liquid phase to fibers of graphite oxide. Resistivity increases as high as 10,000 times were obtained, the oxidized fiber decomposed on exposure to atmosphere. A factor of 1,000 remained as a stable increment. The largest change observed was 1,000,000 times. Best results were obtained on the most highly graphitized fibers. Electrochemical oxidation yielded a lower increase--about 10 times, but provided a controllable method of synthesis and insight to the mechanism of reaction. Tensile tests indicated that the strength of the fiber on oxidation was decreased by no more than 25 percent.

  7. Large-scale carbon fiber tests

    NASA Technical Reports Server (NTRS)

    Pride, R. A.

    1980-01-01

    A realistic release of carbon fibers was established by burning a minimum of 45 kg of carbon fiber composite aircraft structural components in each of five large scale, outdoor aviation jet fuel fire tests. This release was quantified by several independent assessments with various instruments developed specifically for these tests. The most likely values for the mass of single carbon fibers released ranged from 0.2 percent of the initial mass of carbon fiber for the source tests (zero wind velocity) to a maximum of 0.6 percent of the initial carbon fiber mass for dissemination tests (5 to 6 m/s wind velocity). Mean fiber lengths for fibers greater than 1 mm in length ranged from 2.5 to 3.5 mm. Mean diameters ranged from 3.6 to 5.3 micrometers which was indicative of significant oxidation. Footprints of downwind dissemination of the fire released fibers were measured to 19.1 km from the fire.

  8. Carbon fiber content measurement in composite

    NASA Astrophysics Data System (ADS)

    Wang, Qiushi

    Carbon fiber reinforced polymers (CFRPs) have been widely used in various structural applications in industries such as aerospace and automotive because of their high specific stiffness and specific strength. Their mechanical properties are strongly influenced by the carbon fiber content in the composites. Measurement of the carbon fiber content in CFRPs is essential for product quality control and process optimization. In this work, a novel carbonization-in-nitrogen method (CIN) is developed to characterize the fiber content in carbon fiber reinforced thermoset and thermoplastic composites. In this method, a carbon fiber composite sample is carbonized in a nitrogen environment at elevated temperatures, alongside a neat resin sample. The carbon fibers are protected from oxidization while the resin (the neat resin and the resin matrix in the composite sample) is carbonized under the nitrogen environment. The residue of the carbonized neat resin sample is used to calibrate the resin carbonization rate and calculate the amount of the resin matrix in the composite sample. The new method has been validated on several thermoset and thermoplastic resin systems and found to yield an accurate measurement of fiber content in carbon fiber polymer composites. In order to further understand the thermal degradation behavior of the high temperature thermoplastic polymer during the carbonization process, the mechanism and the kinetic model of thermal degradation behavior of carbon fiber reinforced poly (phenylene sulfide) (CPPS) are studied using thermogravimetry analysis (TGA). The CPPS is subjected to TGA in an air and nitrogen atmosphere at heating rates from 5 to 40°C min--1. The TGA curves obtained in air are different from those in nitrogen. This demonstrates that weight loss occurs in a single stage in nitrogen but in two stages in air. To elucidate this difference, thermal decomposition kinetics is analyzed by applying the Kissinger, Flynn-Wall-Ozawa, Coat-Redfern and

  9. Analytical Evaluation of Drop Tests Performed on Nine 18-Inch Diameter Standardized DOE Spent Nuclear Fuel Canisters

    SciTech Connect

    Snow, Spencer David; Morton, Dana Keith; Rahl, Tommy Ervin; Ware, Arthur Gates; Smith, Nancy Lynn

    2000-07-01

    During fiscal year 1999, a total of nine 18-inch diameter test canisters were fabricated at the Idaho National Engineering & Environmental Laboratory (INEEL) to represent the standardized Department of Energy (DOE) Spent Nuclear Fuel (SNF) canister design. Various "worst case" internal loadings were incorporated. Seven of the test canisters were 15-foot long and weighed approximately 6000 pounds, while two were 10-foot long and weighed 3000 and 3800 pounds. Seven of the test canisters were dropped from thirty feet onto an essentially unyielding flat surface and one of the test canisters was dropped from 40-inches onto a 6-inch diameter puncture post. The final test canister was dropped from 24 inches onto a 2-inch thick vertically oriented steel plate, and then tipped over to impact another 2-inch thick vertically oriented steel plate. This last test was attempting to represent a canister dropping onto another larger container such as a repository disposal container. All drop testing was performed at Sandia National Laboratory (SNL). The nine test canisters experienced varying degrees of damage to their skirts, lifting rings, and pressure boundary components (heads and main body). However, all of the canisters were shown to have maintained their pressure boundary (through pressure testing), and the four worst damaged canisters were also shown to be leaktight (via helium leak testing performed at the INEEL). Pre-drop and post-drop test canister finite element modeling was performed at the INEEL in support of the canister drop test program. All model evaluations were performed using the ABAQUS/Explicit software. The finite element models representing the test canisters accurately (though at times, slightly conservatively) predicted the actual test canister responses during the defined drop events.This paper will discuss highlights of the drop testing program and will give detailed comparisons of analysis versus actual test results.

  10. Risk analysis approach. [of carbon fiber release

    NASA Technical Reports Server (NTRS)

    Huston, R. J.

    1979-01-01

    The assessment of the carbon fiber hazard is outlined. Program objectives, requirements of the risk analysis, and elements associated with the physical phenomena of the accidental release are described.

  11. Carbon fiber composite molecular sieves

    SciTech Connect

    Burchell, T.D.; Rogers, M.R.; Williams, A.M.

    1996-06-01

    The removal of CO{sub 2} is of significance in several energy applications. The combustion of fossil fuels, such as coal or natural gas, releases large volumes of CO{sub 2} to the environment. Several options exist to reduce CO{sub 2} emissions, including substitution of nuclear power for fossil fuels, increasing the efficiency of fossil plants and capturing the CO{sub 2} prior to emission to the environment. All of these techniques have the attractive feature of limiting the amount of CO{sub 2} emitted to the atmosphere, but each has economic, technical, or societal limitations. In the production of natural gas, the feed stream from the well frequently contains contaminants and diluents which must be removed before the gas can enter the pipeline distribution system. Notable amongst these diluent gasses is CO{sub 2}, which has no calorific value. Currently, the pipeline specification calls for <2 mol % CO{sub 2} in the gas. Gas separation is thus a relevant technology in the field of energy production. A novel separation system based on a parametric swing process has been developed that utilizes the unique combination of properties exhibited by our carbon fiber composite molecular sieve (CFCMS).

  12. Characterization of electrospun lignin based carbon fibers

    SciTech Connect

    Poursorkhabi, Vida; Mohanty, Amar; Misra, Manjusri

    2015-05-22

    The production of lignin fibers has been studied in order to replace the need for petroleum based precursors for carbon fiber production. In addition to its positive environmental effects, it also benefits the economics of the industries which cannot take advantage of carbon fiber properties because of their high price. A large amount of lignin is annually produced as the byproduct of paper and growing cellulosic ethanol industry. Therefore, finding high value applications for this low cost, highly available material is getting more attention. Lignin is a biopolymer making about 15 – 30 % of the plant cell walls and has a high carbon yield upon carbonization. However, its processing is challenging due to its low molecular weight and also variations based on its origin and the method of separation from cellulose. In this study, alkali solutions of organosolv lignin with less than 1 wt/v% of poly (ethylene oxide) and two types of lignin (hardwood and softwood) were electrospun followed by carbonization. Different heating programs for carbonization were tested. The carbonized fibers had a smooth surface with an average diameter of less than 5 µm and the diameter could be controlled by the carbonization process and lignin type. Scanning electron microscopy (SEM) was used to study morphology of the fibers before and after carbonization. Thermal conductivity of a sample with amorphous carbon was 2.31 W/m.K. The electrospun lignin carbon fibers potentially have a large range of application such as in energy storage devices and water or gas purification systems.

  13. Effects of carbon fibers on consumer products

    NASA Technical Reports Server (NTRS)

    Wise, R. A.; Lovett, C. D.

    1980-01-01

    The potential effects of carbon fibers on consumer products such as dishwashers, microwave ovens, and smoke detectors were investigated. The investigation was divided into two categories to determine the potential faults and hazards that could occur if fibers should enter the electrical circuits of the selected appliances. The categories were a fault analysis and a hazard analysis. Hazards considered were fire, flood, physical harm, explosion, and electrical shock. Electrical shock was found to be a possible occurrence related to carbon fibers. Faults were considered to be any effect on the performance of an appliance which would result in complaint or require service action.

  14. Enhanced carbon nanotube fibers by polyimide

    NASA Astrophysics Data System (ADS)

    Fang, Chao; Zhao, Jingna; Jia, Jingjing; Zhang, Zuoguang; Zhang, Xiaohua; Li, Qingwen

    2010-11-01

    The performance of carbon nanotube (CNT) fibers is limited by the intertube characteristics. Here we report a direct method of curing to improve mechanical properties of poly(amic acid)-infiltrated fibers. After curing at 190 °C for 60 min the fibers composed of double- and triple-walled CNTs, their strength is stably improved by 30.3%, from 1.58 to 2.06 GPa. The enhancement arises from the increase in shear stress between tube surfaces, by measuring the static frictional force of CNT fibers. Due to the existence of CNTs, the imidization temperature of polyimide drops greatly from 218 to 157 °C.

  15. Carbon nanotube-doped polymer optical fiber.

    PubMed

    Uchida, Sho; Martinez, Amos; Song, Yong-Won; Ishigure, Takaaki; Yamashita, Shinji

    2009-10-15

    We present a method to fabricate graded-index multimode polymer optical fibers doped with carbon nanotubes (CNTs). Such fiber structures provide the means to fully utilize the exceptional optical properties of the CNTs. The core region of the fiber is composed of CNTs and polymethyl methacrylate (PMMA) with the addition of diphenyl sulfide (DPS), which acts as the dispersion stabilizer of CNTs in PMMA as well as the dopant to increase the refractive index of the core. Utilizing 2.5 cm of the fiber as a saturable absorber, passively mode-locked lasing with duration of 3.0 ps and repetition rate of 30.3 MHz was demonstrated.

  16. High Performance Multifunctional Carbon Nanotube Fibers

    NASA Astrophysics Data System (ADS)

    Dalton, Alan; Collins, Steve; Munoz, Edgar; Razal, Joselito; Ebron, Von; Ferraris, John; Baughman, Ray

    2003-03-01

    Exploiting the extraordinary properties of carbon nanotubes has remained somewhat elusive due to the inability to process the as produced insoluble soot into functional macroscopic assemblies. To this end we have developed a simple but effective method to produce continuous, homogeneous fibers containing carbon nanotubes having as-spun mechanical properties that compare very favorably to recognized synthetic and natural "super fibers" such as Kevlar and spider silk. By using novel spinning apparatus, spinning solutions, and spinning coagulants, we have spun nanotube fibers having record lengths, record tensile strengths, and having an energy-to-break (toughness) higher than any material that we have found. As an example of the potential multi-functionalities of our fibers, we have fabricated fiber supercapacitors, which we weave into textiles.

  17. Carbon fiber production at low temperatures from polyacrylonitrile

    NASA Technical Reports Server (NTRS)

    Cagliostro, D. E.

    1980-01-01

    Recent safety considerations have sought to lower the electrical conductivity of carbon fibers. Carbon fibers produced from polyacrylonitrile at low carbonization temperatures (600-900 C) possess low electrical conductivity but do not possess adequate strength. Low-temperature processes are described which improve fiber strength but do not increase electrical conductivity substantially. The processes result in a carbon fiber with nearly twice the tensile strength compared to the old process. Process development and its effect on fiber properties are reported.

  18. FIBER LENGTH DISTRIBUTION MEASUREMENT FOR LONG GLASS AND CARBON FIBER REINFORCED INJECTION MOLDED THERMOPLASTICS

    SciTech Connect

    Kunc, Vlastimil; Frame, Barbara J; Nguyen, Ba N.; TuckerIII, Charles L.; Velez-Garcia, Gregorio

    2007-01-01

    Procedures for fiber length distribution (FLD) measurement of long fiber reinforced injection molded thermoplastics were refined for glass and carbon fibers. Techniques for sample selection, fiber separation, digitization and length measurement for both fiber types are described in detail. Quantitative FLD results are provided for glass and carbon reinforced polypropylene samples molded with a nominal original fiber length of 12.7 mm (1/2 in.) using equipment optimized for molding short fiber reinforced thermoplastics.

  19. Large diameter carbon-boron fiber

    NASA Technical Reports Server (NTRS)

    Veltri, R. D.; Jacob, B. A.; Galasso, F. S.

    1975-01-01

    Investigations concerned with a development of large-diameter carbon fibers are considered, taking into account the employment of vapor deposition techniques. In the experiments a carbon monofilament substrate is used together with reacting gases which consist of combinations of hydrogen, methane, and boron trichloride. It is found that the described approach can be used to obtain a large-diameter carbon filament containing boron. The filament has reasonable strength and modulus properties.

  20. Thermoplastic coated carbon fibers for textile preforms

    NASA Technical Reports Server (NTRS)

    Allen, L. E.; Edie, D. D.; Lickfield, G. C.; Mccollum, J. R.

    1988-01-01

    A continuous process for producing prepreg from carbon fiber and thermoplastic matrix is described. After the tow has been spread using a pneumatic device, the process utilizes a fluidized bed to apply thermoplastic powder to the bundle. Finally, direct electrical heating of the coated fiber tow melts the polymer on the individual fibers, creating a uniform and extremely flexible prepreg. The efficiency of the process was evaluated during initial trials in which a thermoplastic polyimide, LaRC-TPI, was applied to T-300, 3K (3000 filament) carbon fiber tow. The physical properties of unidirectional composite specimens fabricated from this prepreg were measured, and the matrix uniformity and void content of the samples was determined. The results of these evaluations are detailed and discussed.

  1. Coating for gasifiable carbon-graphite fibers

    NASA Technical Reports Server (NTRS)

    Harper-Tervet, Jan (Inventor); Dowler, Warren L. (Inventor); Yen, Shiao-Ping S. (Inventor); Mueller, William A. (Inventor)

    1982-01-01

    A thin, uniform, firmly adherent coating of metal gasification catalyst is applied to a carbon-graphite fiber by first coating the fiber with a film-forming polymer containing functional moieties capable of reaction with the catalytic metal ions. Multivalent metal cations such as calcium cross-link the polymer such as a polyacrylic acid to insolubilize the film by forming catalytic metal macro-salt links between adjacent polymer chains. The coated fibers are used as reinforcement for resin composites and will gasify upon combustion without evolving conductive airborne fragments.

  2. Hybrid solar cell on a carbon fiber.

    PubMed

    Grynko, Dmytro A; Fedoryak, Alexander N; Smertenko, Petro S; Dimitriev, Oleg P; Ogurtsov, Nikolay A; Pud, Alexander A

    2016-12-01

    In this work, a method to assemble nanoscale hybrid solar cells in the form of a brush of radially oriented CdS nanowire crystals around a single carbon fiber is demonstrated for the first time. A solar cell was assembled on a carbon fiber with a diameter of ~5-10 μm which served as a core electrode; inorganic CdS nanowire crystals and organic dye or polymer layers were successively deposited on the carbon fiber as active components resulting in a core-shell photovoltaic structure. Polymer, dye-sensitized, and inverted solar cells have been prepared and compared with their analogues made on the flat indium-tin oxide electrode.

  3. Hybrid solar cell on a carbon fiber.

    PubMed

    Grynko, Dmytro A; Fedoryak, Alexander N; Smertenko, Petro S; Dimitriev, Oleg P; Ogurtsov, Nikolay A; Pud, Alexander A

    2016-12-01

    In this work, a method to assemble nanoscale hybrid solar cells in the form of a brush of radially oriented CdS nanowire crystals around a single carbon fiber is demonstrated for the first time. A solar cell was assembled on a carbon fiber with a diameter of ~5-10 μm which served as a core electrode; inorganic CdS nanowire crystals and organic dye or polymer layers were successively deposited on the carbon fiber as active components resulting in a core-shell photovoltaic structure. Polymer, dye-sensitized, and inverted solar cells have been prepared and compared with their analogues made on the flat indium-tin oxide electrode. PMID:27216603

  4. CARBON FIBER COMPOSITES IN HIGH VOLUME

    SciTech Connect

    Warren, Charles David; Das, Sujit; Jeon, Dr. Saeil

    2014-01-01

    Vehicle lightweighting represents one of several design approaches that automotive and heavy truck manufacturers are currently evaluating to improve fuel economy, lower emissions, and improve freight efficiency (tons-miles per gallon of fuel). With changes in fuel efficiency and environmental regulations in the area of transportation, the next decade will likely see considerable vehicle lightweighting throughout the ground transportation industry. Greater use of carbon fiber composites and light metals is a key component of that strategy. This paper examines the competition between candidate materials for lightweighting of heavy vehicles and passenger cars. A 53-component, 25 % mass reduction, body-in-white cost analysis is presented for each material class, highlighting the potential cost penalty for each kilogram of mass reduction and then comparing the various material options. Lastly, as the cost of carbon fiber is a major component of the elevated cost of carbon fiber composites, a brief look at the factors that influence that cost is presented.

  5. Hybrid solar cell on a carbon fiber

    NASA Astrophysics Data System (ADS)

    Grynko, Dmytro A.; Fedoryak, Alexander N.; Smertenko, Petro S.; Dimitriev, Oleg P.; Ogurtsov, Nikolay A.; Pud, Alexander A.

    2016-05-01

    In this work, a method to assemble nanoscale hybrid solar cells in the form of a brush of radially oriented CdS nanowire crystals around a single carbon fiber is demonstrated for the first time. A solar cell was assembled on a carbon fiber with a diameter of ~5-10 μm which served as a core electrode; inorganic CdS nanowire crystals and organic dye or polymer layers were successively deposited on the carbon fiber as active components resulting in a core-shell photovoltaic structure. Polymer, dye-sensitized, and inverted solar cells have been prepared and compared with their analogues made on the flat indium-tin oxide electrode.

  6. Novel method for carbon nanofilament growth on carbon fibers

    SciTech Connect

    Phillips, Johathan; Luhrs, Claudia; Terani, Mehran; Al - Haik, Marwan; Garcia, Daniel; Taha, Mahmoud R

    2009-01-01

    Fiber reinforced structural composites such as fiber reinforced polymers (FRPs) have proven to be key materials for blast mitigation due to their enhanced mechanical performance. However, there is a need to further increase total energy absorption of the composites in order to retain structural integrity in high energy environments, for example, blast events. Research has shown that composite failure in high energy environments can be traced to their relatively low shear strength attributed to the limited bond strength between the matrix and the fibers. One area of focus for improving the strength of composite materials has been to create 'multi-scale' composites. The most common approach to date is to introduce carbon nanotubes into a more traditional composite consisting of epoxy with embedded micron scale fibers. The inclusion of carbon nanotubes (CNT) clearly toughens different matrices. Depositing CNT in brittle matrix increases stiffness by orders of magnitude. Currently, this approach to create multiscale composites is limited due to the difficulty of dispersing significant amounts of nanotubes. It has repeatedly been reported that phase separation occurs above relatively low weight percent loading (ca. 3%) due to the strong van der Waals forces between CNTs compared with that between CNT and polymer. Hence, the nanotubes tend to segregate and form inclusions. One means to prevent nanotube or nanofilament agglomeration is to anchor one end of the nanostructure, thereby creating a stable multi-phase structure. This is most easily done by literally growing the CNTs directly on micron scale fibers. Recently, CNT were grown on carbon fibers, both polyacrylonitrile- (PAN-) and pitch-based, by hot filament chemical vapor deposition (HFCVD) using H2 and CH4 as precursors. Nickel clusters were electrodeposited on the fiber surfaces to catalyze the growth and uniform CNT coatings were obtained on both the PAN- and pitch-based carbon fibers. Multiwalled CNTs with

  7. Carbon-Fiber Brush Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Knowles, Timothy R.

    2004-01-01

    Velvetlike and brushlike pads of carbon fibers have been proposed for use as mechanically compliant, highly thermally conductive interfaces for transferring heat. A pad of this type would be formed by attaching short carbon fibers to either or both of two objects that one desires to place in thermal contact with each other. The purpose of using a thermal-contact pad of this or any other type is to reduce the thermal resistance of an interface between a heat source and a heat sink.

  8. Carbon Fiber Reinforced Carbon Composite Valve for an Internal Combustion Engine

    NASA Technical Reports Server (NTRS)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor)

    1999-01-01

    A carbon fiber reinforced carbon composite valve for internal combustion engines and the like formed of continuous carbon fibers throughout the valve's stem and head is disclosed. The valve includes braided carbon fiber material over axially aligned unidirectional carbon fibers forming a valve stem; the braided and unidirectional carbon fibers being broomed out at one end of the valve stem forming the shape of the valve head; the valve-shaped structure being densified and rigidized with a matrix of carbon containing discontinuous carbon fibers: and the finished valve being treated to resist oxidation. Also disclosed is a carbon matrix plug containing continuous and discontinuous carbon fibers and forming a net-shape valve head acting as a mandrel over which the unidirectional and braided carbon fibers are formed according to textile processes. Also disclosed are various preform valves and processes for making finished and preform carbon fiber reinforced carbon composite valves.

  9. CTE Measurements of Carbon Fibers in ESEM

    NASA Technical Reports Server (NTRS)

    Effinger, Michael; Ochoa, Ozden; Munafo, Paul M. (Technical Monitor)

    2001-01-01

    The strong appeal of carbon fiber reinforced ceramic matrix and carbon-carbon composites arises from their promising high temperature performance within laboratory-simulated nozzle, leading edge and combustor environments. The main drawback in these systems are two fold; namely oxidation affinity and CTE mismatch. To date the emphasis has been on axial CTE mismatch with the push on estimating (component) laminate level data. However, in heterogeneous and anisotropic systems, all failure mechanisms are at micro or nano scales. This paper will report plans and progress on single carbon fibers efforts in order to develop its temperature dependent, anisotropic thermophysical and thermomechanical properties using combination of x-ray spectroscopy and environmental scanning electron microscopy to capture circumferential expansion from 20-900 C in within the SEM chamber. Surface roughness measurements were also determined. Crystallinity was also determined by the quality of the electron diffraction (ED) patterns.

  10. Designing the Structure of Carbon Fibers for Optimal Mechanical Properties

    SciTech Connect

    Ozcan, Soydan; Vautard, Frederic; Naskar, Amit K

    2014-01-01

    Carbon fiber manufacturing follows generic processing steps: formation of thermoplastic fibers, stabilization, and carbonization. The final structures and end properties of the carbon fiber can differ significantly depending on the precursor chemistry and the associated processing sciences. Polyacrylonitrile (PAN) and mesophase pitch are the predominant precursors used in the production of carbon fibers. PAN-based carbon fibers consist of nanocrystalline graphitic domains typically 1.5 5 nm in size surrounded by amorphous carbon; in contrast, pitch-based carbon fibers are 10 50 nm crystallites with the graphitic (002) planes mostly aligned parallel to the fiber axis. It has been seen that the skin core structure of PAN-based carbon fibers plays a significant role in their mechanical properties. Designing a more homogenous carbon fiber microstructure by controlling the starting polymer and process parameters results in a different set of tensile strengths and elastic moduli. In this study the microstructural defect distribution (0.1 200 nm), measured by small-angle X-ray scattering, was shown to be directly related to the tensile strength of the carbon fibers. Here the formation of carbon structures from various polymer precursors is reviewed. Such a comprehensive understanding offers the opportunity to design carbon fiber microstructures with improved properties and to ultimately create new types of carbon fibers from alternative precursors at reduced cost.

  11. Carbon Fibers from Chicken Feather Keratin

    NASA Astrophysics Data System (ADS)

    Miller, Melissa E.; Wool, Richard

    2006-03-01

    As the availability of synthetic and fossil-fuel based resources is becoming limited, bio-based materials offer an environmentally friendly alternative. Chicken feathers remain a huge agricultural waste. The feathers are comprised of approximately 97% keratin, but are currently used only to enrich animal feed. However, this usage is becoming a problem with the spread of diseases such as Bovine Spongiform Encephalopathy, commonly called ``Mad Cow Disease.'' The hollow, microcrystalline, oriented keratin feather fibers offer a novel, low cost approach to producing carbon fibers through controlled pyrolysis. Carbonized feather fibers (CFF) were prepared by first heating to 225 ^oC (below the melting point)in N2 for 26 hours to crosslink and stabilize the fiber structure; then carbonization occurred by increasing the temperature to 450 ^oC for two more hours. The resulting CFF were hollow, stiff and strong and had an affine 80% weight loss, which is near the theoretical value for the C-content of keratin. Initial studies showed that a composite with the CFF and an epoxidized soybean oil (AESO) gave an improved fiber modulus ECFF of order 13.5--66.1 GPa. With continued research, the goals are to increase the stiffness of the feathers to 100 GPa, while increasing the strength in the range of 5-10 GPa.

  12. Metal fiber - carbon electrodes for oxygen reduction

    NASA Astrophysics Data System (ADS)

    Smith, Robert Fendlay

    An investigation was carried out to determine activities for oxygen reduction and current efficiencies to hydrogen peroxide of commercially available nickel fibers, carbon fibers, and carbon powders. The activities and current efficiencies were determined by conducting Rotating Ring Disk Electrode Experiments (RRDE) on porous electrodes that utilize an interlocking network of metal fibers with carbon fibers and/or powders. Experimentation was also done using PTFE - carbon powder and PTFE - nickel fiber paste electrodes to remove any porosity and symbiotic effects of the nickel - carbon electrodes. Results of the traditional flat plate PTFE electrodes were compared to the porous electrodes to verify the proposed mathematical viability of porous electrode RRDE. RRDE experiments showed that the most active carbons for oxygen reduction have a surface area to volume ratio of 1000 m2/g, and current rent efficiency to hydrogen peroxide was increased as the average pore size increased. A mathematical model and half-cell polarization experiments were used to characterize and optimize oxygen reduction in gas diffusion electrodes consisting of carbon fibers and/or powders entrapped in a sinter-locked network of nickel microfibers. Important electrode physical parameters, such as nickel fiber loading (0.005 to 0.01 g/cm2) , nickel fiber diameter (2 to 12 mum), void volume (73 to 96%), distance of the active layer from the gas supply (0 to 0.005 cm), and addition of a peroxide decomposition catalyst (0 to 0.004 g/cm2) were systematically varied to determine their effects on electrode performance. Experimentally determined total currents and current efficiencies to hydrogen peroxide were compared to calculated values for model verification. Other important parameters, including intra-electrode oxygen and hydrogen peroxide concentrations, overpotentials, and reaction rates, were simulated to help optimize the electrode. Fabricated metal fiber-carbon electrodes were compared to a

  13. [Fusion implants of carbon fiber reinforced plastic].

    PubMed

    Früh, H J; Liebetrau, A; Bertagnoli, R

    2002-05-01

    Carbon fiber reinforced plastics (CFRP) are used in the medical field when high mechanical strength, innovative design, and radiolucency (see spinal fusion implants) are needed. During the manufacturing process of the material CFRP carbon fibers are embedded into a resin matrix. This resin material could be thermoset (e.g., epoxy resin EPN/DDS) or thermoplastic (e.g., PEAK). CFRP is biocompatible, radiolucent, and has higher mechanical capabilities compared to other implant materials. This publication demonstrates the manufacturing process of fusion implants made of a thermoset matrix system using a fiber winding process. The material has been used clinically since 1994 for fusion implants of the cervical and lumbar spine. The results of the fusion systems CORNERSTONE-SR C (cervical) and UNION (lumbar) showed no implant-related complications. New implant systems made of this CFRP material are under investigation and are presented.

  14. Microwave axial dielectric properties of carbon fiber.

    PubMed

    Hong, Wen; Xiao, Peng; Luo, Heng; Li, Zhuan

    2015-01-01

    Randomly distributed carbon fibers (CFs) reinforced epoxy resin composites are prepared by the pouring method, the dielectric properties of CF composites with different fiber content and length have been performed in the frequency range from 8.2 to 12.4 GHz. The complex permittivity of the composite increases with the fiber length, which is attributed to the decrease of depolarization field, and increases with the volume fraction, which is attributed to the increase of polarization. A formula, based on the theory of Reynolds-Hugh, is proposed to calculate the effective permittivity of CF composites, and validated by the experiments. The proposed formula is further applied to derive the axial permittivity of CF and analyze the effect of fiber length on the axial permittivity. PMID:26477579

  15. Microwave axial dielectric properties of carbon fiber

    PubMed Central

    Hong, Wen; Xiao, Peng; Luo, Heng; Li, Zhuan

    2015-01-01

    Randomly distributed carbon fibers (CFs) reinforced epoxy resin composites are prepared by the pouring method, the dielectric properties of CF composites with different fiber content and length have been performed in the frequency range from 8.2 to 12.4 GHz. The complex permittivity of the composite increases with the fiber length, which is attributed to the decrease of depolarization field, and increases with the volume fraction, which is attributed to the increase of polarization. A formula, based on the theory of Reynolds-Hugh, is proposed to calculate the effective permittivity of CF composites, and validated by the experiments. The proposed formula is further applied to derive the axial permittivity of CF and analyze the effect of fiber length on the axial permittivity. PMID:26477579

  16. Overview of the carbon fiber problem

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Carbon fibers (CF) composite structures are being utilized more as alternatives to metals in both civilian and military applications. They are valued for their light weight and high strength as well as for their ease of designing structures with specific shapes and sizes. However, a problem may exist due to the high conductivity of CF. CF are manufactured from a precursor material which is subjected to great stress and heat treatment causing a change in the physical and electrical properties. The fibers are bound together by a matrix of epoxy. In the event of fire (aircraft accident) the epoxy would burn away releasing these fibers into the atmosphere. When these fibers come in contact with electronic equipment, they might cause damage to by settling on electrical junctions. An overview is given of the objectives for a study, and the approach and methodology developed for determination of risk profiles.

  17. Microwave axial dielectric properties of carbon fiber

    NASA Astrophysics Data System (ADS)

    Hong, Wen; Xiao, Peng; Luo, Heng; Li, Zhuan

    2015-10-01

    Randomly distributed carbon fibers (CFs) reinforced epoxy resin composites are prepared by the pouring method, the dielectric properties of CF composites with different fiber content and length have been performed in the frequency range from 8.2 to 12.4 GHz. The complex permittivity of the composite increases with the fiber length, which is attributed to the decrease of depolarization field, and increases with the volume fraction, which is attributed to the increase of polarization. A formula, based on the theory of Reynolds-Hugh, is proposed to calculate the effective permittivity of CF composites, and validated by the experiments. The proposed formula is further applied to derive the axial permittivity of CF and analyze the effect of fiber length on the axial permittivity.

  18. Risk methodology overview. [for carbon fiber release

    NASA Technical Reports Server (NTRS)

    Credeur, K. R.

    1979-01-01

    Some considerations of risk estimation, how risk is measured, and how risk analysis decisions are made are discussed. Specific problems of carbon fiber release are discussed by reviewing the objective, describing the main elements, and giving an example of the risk logic and outputs.

  19. Carbon Dioxide Laser Fiber Optics In Endoscopy

    NASA Astrophysics Data System (ADS)

    Fuller, Terry A.

    1982-12-01

    Carbon dioxide laser surgery has been limited to a great extent to surgical application on the integument and accessible cavities such as the cervix, vagina, oral cavities, etc. This limitation has been due to the rigid delivery systems available to all carbon dioxide lasers. Articulating arms (series of hollow tubes connected by articulating mirrors) have provided an effective means of delivery of laser energy to the patient as long as the lesion was within the direct line of sight. Even direct line-of-sight applications were restricted to physical dimension of the articulating arm or associated hand probes, manipulators and hollow tubes. The many attempts at providing straight endoscopic systems to the laser only stressed the need for a fiber optic capable of carrying the carbon dioxide laser wavelength. Rectangular and circular hollow metal waveguides, hollow dielectric waveguides have proven ineffective to the stringent requirements of a flexible surgical delivery system. One large diameter (1 cm) fiber optic delivery system, incorporates a toxic thalliumAbased fiber optic material. The device is an effective alternative to an articulating arm for external or conventional laser surgery, but is too large and stiff to use as a flexible endoscopic tool. The author describes the first highly flexible inexpensive series of fiber optic systems suitable for either conventional or endoscopic carbon dioxide laser surgery. One system (IRFLEX 3) has been manufactured by Medlase, Inc. for surgical uses capable of delivering 2000w, 100 mJ pulsed energy and 15w continuous wave. The system diameter is 0.035 inches in diameter. Surgically suitable fibers as small as 120 um have been manufactured. Other fibers (IRFLEX 142,447) have a variety of transmission characteristics, bend radii, etc.

  20. Experimental and analytical studies for the NASA carbon fiber risk assessment

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Various experimental and analytical studies performed for the NASA carbon fiber risk assessment program are described with emphasis on carbon fiber characteristics, sensitivity of electrical equipment and components to shorting or arcing by carbon fibers, attenuation effect of carbon fibers on aircraft landing aids, impact of carbon fibers on industrial facilities. A simple method of estimating damage from airborne carbon fibers is presented.

  1. Thermoplastic coating of carbon fibers

    NASA Technical Reports Server (NTRS)

    Edie, D. D.; Lickfield, G. C.; Drews, M. J.; Ellison, M. S.; Allen, L. E.; Mccollum, J. R.; Thomas, H. L.

    1988-01-01

    Now that quantities of prepreg were made on the thermoplastic coating line, they are being formed into both textile preform structures and directly into composite samples. The textile preforms include both woven and knitted structures which will be thermoformed into a finished part. In order to determine if the matrix resin is properly adhering to the fibers or if voids are being formed in the coating process, the tensile strength and modulus of these samples will be tested. The matrix uniformity of matrix distribution in these samples is also being determined using an image analyzer.

  2. Improving the interlaminar shear strength of carbon fiber-epoxy composites through carbon fiber bromination

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Maciag, Carolyn

    1987-01-01

    The use of bromine to improve the interlaminar shear strength of PAN-based carbon fibers was investigated. Composite test specimens fabicated from brominated T-300 fibers and a MY720 matrix exhibited on average a 30% improvement in ILSS over their pristine counterparts. Mass, electrical resistivity, density, contact angle, and scanning Auger microscopy results suggested a mechanism in which the bromine was covalently bonded to the surface of the fiber, and this resulted in an increased van der Waal's adhesion between fiber and matrix.

  3. Carbon Fiber Foam Composites and Methods for Making the Same

    NASA Technical Reports Server (NTRS)

    Leseman, Zayd Chad (Inventor); Atwater, Mark Andrew (Inventor); Phillips, Jonathan (Inventor)

    2014-01-01

    Exemplary embodiments provide methods and apparatus of forming fibrous carbon foams (FCFs). In one embodiment, FCFs can be formed by flowing a fuel rich gas mixture over a catalytic material and components to be encapsulated in a mold to form composite carbon fibers, each composite carbon fiber having a carbon phase grown to encapsulate the component in situ. The composite carbon fibers can be intertwined with one another to form FCFs having a geometry according to the mold.

  4. Carbon fiber composite molecular sieves

    SciTech Connect

    Burchell, T.D.; Rogers, M.R.

    1997-12-01

    Monolithic adsorbents based on isotropic pitch fibers have been developed jointly by ORNL and the University of Kentucky, Center for Applied Energy Research. The monoliths are attractive for gas separation and storage applications because of their unique combination of physical properties and microporous structure. Currently at ORNL the monoliths are produced in billets that are 10 cm in diameter and 25 cm in length. The monolithic adsorbent material is being considered for guard bed applications on a natural gas (NG) powered device. In order for the material to be successful in this application, one must attain a uniform activation to modest micropore volumes throughout the large monoliths currently being produced. Here the authors report the results of a study directed toward attaining uniform activation in these billets.

  5. Carbon Nanotubes Growth on Graphite Fibers

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Lehoczky, S. L.; Muntele, I.; Ila, D.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Carbon nanotubes (CNT) were synthesized on graphite fibers by thermal Chemical Vapor Deposition (CVD). On the fiber surface, iron nanoparticles are coated and act as catalysts for CNT growth. The growth temperature ranges from 550 to 1000 C at an ambient pressure. Methane and hydrogen gases with methane contents of 10% to 100% are used for the CNT synthesis. At high growth temperatures (greater than 800 C), the rapid inter-diffusion of the transition metal iron on the graphite surface results in a rough fiber surface with no CNT grown on the surface. When the growth temperature is relatively low (650 - 800 C), CNT are fabricated on the graphite surface with catalytic particles on the nanotube top ends. Using micro Raman spectroscopy in the breath mode region, single-walled or multi-walled CNT can be determined, depending on methane concentrations.

  6. Activated carbon fibers and engineered forms from renewable resources

    DOEpatents

    Baker, Frederick S.

    2010-06-01

    A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

  7. Activated carbon fibers and engineered forms from renewable resources

    DOEpatents

    Baker, Frederick S

    2013-02-19

    A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

  8. Production of superconductor/carbon bicomponent fibers

    NASA Technical Reports Server (NTRS)

    Wise, S. A.; Fain, C. C.; Leigh, H. D.

    1991-01-01

    Certain materials are unable to be drawn or spun into fiber form due to their improper melting characteristics or brittleness. However, fibrous samples of such materials are often necessary for the fabrication of intricate shapes and composites. In response to this problem, a unique process, referred to as the piggyback process, was developed to prepare fibrous samples of a variety of nonspinnable ceramics. In this technique, specially produced C shaped carbon fibers serve as micromolds to hold the desired materials prior to sintering. Depending on the sintering atmosphere used, bicomponent or single component fibers result. While much has been shown worldwide concerning the YBa2Cu3O(7-x) superconductor, fabrication into unique forms has proven quite difficult. However, a variety of intricate shapes are necessary for rapid commercialization of the superconducting materials. The potential for producing fibrous samples of the YBa2Cu3O(7-x) compound by the piggyback process is being studied. Various organic and acrylic materials were studied to determine suspending ability, reactivity with the YBa2Cu3O(7-x) compound during long term storage, and burn out characteristics. While many questions were answered with respect to the interfacial reactions between YBa2Cu3O(7-x) and carbon, much work is still necessary to improve the quality of the sintered material if the fibers produced are to be incorporated into useful composite or cables.

  9. Carbon nanotube and graphene nanoribbon-coated conductive Kevlar fibers.

    PubMed

    Xiang, Changsheng; Lu, Wei; Zhu, Yu; Sun, Zhengzong; Yan, Zheng; Hwang, Chi-Chau; Tour, James M

    2012-01-01

    Conductive carbon material-coated Kevlar fibers were fabricated through layer-by-layer spray coating. Polyurethane was used as the interlayer between the Kevlar fiber and carbon materials to bind the carbon materials to the Kevlar fiber. Strongly adhering single-walled carbon nanotube coatings yielded a durable conductivity of 65 S/cm without significant mechanical degradation. In addition, the properties remained stable after bending or water washing cycles. The coated fibers were analyzed using scanning electron microcopy and a knot test. The as-produced fiber had a knot efficiency of 23%, which is more than four times higher than that of carbon fibers. The spray-coating of graphene nanoribbons onto Kevlar fibers was also investigated. These flexible coated-Kevlar fibers have the potential to be used for conductive wires in wearable electronics and battery-heated armors.

  10. Property and Shape Modulation of Carbon Fibers Using Lasers.

    PubMed

    Blaker, Jonny J; Anthony, David B; Tang, Guang; Shamsuddin, Siti-Ros; Kalinka, Gerhard; Weinrich, Malte; Abdolvand, Amin; Shaffer, Milo S P; Bismarck, Alexander

    2016-06-29

    An exciting challenge is to create unduloid-reinforcing fibers with tailored dimensions to produce synthetic composites with improved toughness and increased ductility. Continuous carbon fibers, the state-of-the-art reinforcement for structural composites, were modified via controlled laser irradiation to result in expanded outwardly tapered regions, as well as fibers with Q-tip (cotton-bud) end shapes. A pulsed laser treatment was used to introduce damage at the single carbon fiber level, creating expanded regions at predetermined points along the lengths of continuous carbon fibers, while maintaining much of their stiffness. The range of produced shapes was quantified and correlated to single fiber tensile properties. Mapped Raman spectroscopy was used to elucidate the local compositional and structural changes. Irradiation conditions were adjusted to create a swollen weakened region, such that fiber failure occurred in the laser treated region producing two fiber ends with outwardly tapered ends. Loading the tapered fibers allows for viscoelastic energy dissipation during fiber pull-out by enhanced friction as the fibers plough through a matrix. In these tapered fibers, diameters were locally increased up to 53%, forming outward taper angles of up to 1.8°. The tensile strength and strain to failure of the modified fibers were significantly reduced, by 75% and 55%, respectively, ensuring localization of the break in the expanded region; however, the fiber stiffness was only reduced by 17%. Using harsher irradiation conditions, carbon fibers were completely cut, resulting in cotton-bud fiber end shapes. Single fiber pull-out tests performed using these fibers revealed a 6.75-fold increase in work of pull-out compared to pristine carbon fibers. Controlled laser irradiation is a route to modify the shape of continuous carbon fibers along their lengths, as well as to cut them into controlled lengths leaving tapered or cotton-bud shapes. PMID:27227575

  11. Property and Shape Modulation of Carbon Fibers Using Lasers.

    PubMed

    Blaker, Jonny J; Anthony, David B; Tang, Guang; Shamsuddin, Siti-Ros; Kalinka, Gerhard; Weinrich, Malte; Abdolvand, Amin; Shaffer, Milo S P; Bismarck, Alexander

    2016-06-29

    An exciting challenge is to create unduloid-reinforcing fibers with tailored dimensions to produce synthetic composites with improved toughness and increased ductility. Continuous carbon fibers, the state-of-the-art reinforcement for structural composites, were modified via controlled laser irradiation to result in expanded outwardly tapered regions, as well as fibers with Q-tip (cotton-bud) end shapes. A pulsed laser treatment was used to introduce damage at the single carbon fiber level, creating expanded regions at predetermined points along the lengths of continuous carbon fibers, while maintaining much of their stiffness. The range of produced shapes was quantified and correlated to single fiber tensile properties. Mapped Raman spectroscopy was used to elucidate the local compositional and structural changes. Irradiation conditions were adjusted to create a swollen weakened region, such that fiber failure occurred in the laser treated region producing two fiber ends with outwardly tapered ends. Loading the tapered fibers allows for viscoelastic energy dissipation during fiber pull-out by enhanced friction as the fibers plough through a matrix. In these tapered fibers, diameters were locally increased up to 53%, forming outward taper angles of up to 1.8°. The tensile strength and strain to failure of the modified fibers were significantly reduced, by 75% and 55%, respectively, ensuring localization of the break in the expanded region; however, the fiber stiffness was only reduced by 17%. Using harsher irradiation conditions, carbon fibers were completely cut, resulting in cotton-bud fiber end shapes. Single fiber pull-out tests performed using these fibers revealed a 6.75-fold increase in work of pull-out compared to pristine carbon fibers. Controlled laser irradiation is a route to modify the shape of continuous carbon fibers along their lengths, as well as to cut them into controlled lengths leaving tapered or cotton-bud shapes.

  12. Carbon fiber-reinforced carbon as a potential implant material.

    PubMed

    Adams, D; Williams, D F; Hill, J

    1978-01-01

    A carbon fiber-reinforced carbon is being evaluated as a promising implant material. In a unidirectional composite, high strengths (1200 MN/m2 longitudinal flexural strength) and high modulus (140 GN/m2 flexural modulus) may be obtained with an interlaminar shear strength of 18 MN/m2. Alternatively, layers of fibers may be laid in two directions to give more isotopic properties. The compatibility of the material with bone has been studied by implanting specimens in holes drilled in rat femora. For a period of up to 8 weeks, a thin layer of fibrous tissue bridged the gap between bone and implant; but this tissue mineralizes and by 10 weeks, bone can be observed adjacent to the implant, giving firm fixation. Potential applications include endosseous dental implants where a greater strength in the neck than that provided by unreinforced carbon would be advantageous.

  13. Waste polyvinylchloride derived pitch as a precursor to develop carbon fibers and activated carbon fibers.

    PubMed

    Qiao, W M; Yoon, S H; Mochida, I; Yang, J H

    2007-01-01

    Polyvinylchloride (PVC) was successfully recycled through the solvent extraction from waste pipe with an extraction yield of ca. 86%. The extracted PVC was pyrolyzed by a two-stage process (260 and 410 degrees C) to obtain free-chlorine PVC based pitch through an effective removal of chlorine from PVC during the heat-treatment. As-prepared pitch (softening point: 220 degrees C) was spun, stabilized, carbonized into carbon fibers (CFs), and further activated into activated carbon fibers (ACFs) in a flow of CO2. As-prepared CFs show comparable mechanical properties to commercial CFs, whose maximum tensile strength and modulus are 862 MPa and 62 GPa, respectively. The resultant ACFs exhibit a high surface area of 1200 m2/g, narrow pore size distribution and a low oxygen content of 3%. The study provides an effective insight to recycle PVC from waste PVC and develop a carbon precursor for high performance carbon materials such as CFs and ACFs.

  14. Carbon molecular sieves for air separation from Nomex aramid fibers.

    PubMed

    Villar-Rodil, Silvia; Martínez-Alonso, Amelia; Tascón, Juan M D

    2002-10-15

    Activated carbon fibers prepared from aramid fibers have proved to possess outstanding homogeneity in pore size, most of all when Nomex aramid fiber is used as precursor. Taking advantage of this feature, microporous carbon molecular sieves for air separation have been prepared through carbon vapor deposition of benzene on Nomex-derived carbon fibers activated to two different burnoff degrees. Carbon molecular sieves with good selectivity for this separation and showing acceptable adsorption capacities were obtained from ACFs activated to the two burnoff degrees chosen. PMID:12702417

  15. Oxygen Reactivity of a Carbon Fiber Composite

    SciTech Connect

    Marshall, Theron Devol; Pawelko, Robert James; Anderl, Robert Andrew; Smolik, Galen Richard

    2002-09-01

    Carbon Fiber Composites (CFCs) are often suggested as armor material for the first wall of a fusion plasma chamber due to carbon's low atomic number, high thermal conductivity, and high melting point. However, carbon is chemically reactive in air and will react with ingress air during a Loss of Vacuum Accident and release tritium fuel that has been retained in the carbon. Tritium mobilization and carbon monoxide generation via CFC oxidation are both safety concerns. This paper discusses chemical reactivity experiments that were performed using the state-of-the-art 3-dimensional NB31 CFC produced by SNECMA and a laminar reaction gas of Ar–21 vol% O2. Oxidation reaction rates were measured for CFC temperatures of 525, 600, 700, 800, 900, and 1000 °C and a 100 standard cubic centimeters per minute (sccm) Ar–O2 flow rate. Experiments were also performed at CFC temperatures of 700 and 1000 °C and a 1000 sccm Ar–O2 flow rate. Mass spectral analyses of the exhaust reaction gas suggested that carbon monoxide was the primary reaction at the CFC surface and carbon dioxide was readily produced in the exiting reaction gas. The measured reaction rates compare well with the literature and were used to produce a CFC oxidation curve that is recommended for use in fusion safety analyses.

  16. Electronic equipment vulnerability to fire released carbon fibers

    NASA Technical Reports Server (NTRS)

    Pride, R. A.; Mchatton, A. D.; Musselman, K. A.

    1980-01-01

    The vulnerability of electronic equipment to damage by carbon fibers released from burning aircraft type structural composite materials was investigated. Tests were conducted on commercially available stereo power amplifiers which showed that the equipment was damaged by fire released carbon fibers but not by the composite resin residue, soot and products of combustion of the fuel associated with burning the carbon fiber composites. Results indicate that the failure rates of the equipment exposed to the fire released fiber were consistent with predictions based on tests using virgin fibers.

  17. Vibration damping with active carbon fiber structures

    NASA Astrophysics Data System (ADS)

    Neugebauer, Reimund; Kunze, Holger; Riedel, Mathias; Roscher, Hans-Jürgen

    2007-04-01

    This paper presents a mechatronic strategy for active reduction of vibrations on machine tool struts or car shafts. The active structure is built from a carbon fiber composite with embedded piezofiber actuators that are composed of piezopatches based on the Macro Fiber Composite (MFC) technology, licensed by NASA and produced by Smart Material GmbH in Dresden, Germany. The structure of these actuators allows separate or selectively combined bending and torsion, meaning that both bending and torsion vibrations can be actively absorbed. Initial simulation work was done with a finite element model (ANSYS). This paper describes how state space models are generated out of a structure based on the finite element model and how controller codes are integrated into finite element models for transient analysis and the model-based control design. Finally, it showcases initial experimental findings and provides an outlook for damping multi-mode resonances with a parallel combination of resonant controllers.

  18. Production of superconductor/carbon bicomponent fibers

    NASA Technical Reports Server (NTRS)

    Wise, S. A.; Fain, C. C.; Leigh, H. D.; Sherrill, M.

    1990-01-01

    Certain materials are unable to be drawn or spun into fiber form due to their improper melting characteristics or brittleness. However, fibrous samples of such materials are often necessary for the fabrication of intricate shapes and composites. In response to this problem, a unique process, referred to as the piggyback process, was developed to prepare fibrous samples of a variety of nonspinnable ceramics. In this technique, specially produced C-shaped carbon fibers serve as micromolds to hold the desired materials prior to sintering. Depending on the sintering atmosphere used, bicomponent or single component fibers result. While much has been demonstrated worldwide concerning the YBa2Cu3O(7-x) superconductor, fabrication into unique forms has proven quite difficult. However, a variety of intricate shapes are necessary for rapid commercialization of the superconducting materials. The potential for producing fibrous samples of the YBa2Cu3O(7-x) compound by the piggyback process is being investigated. Various organic and acrylic materials were investigated to determine suspending ability, reactivity with the YBa2Cu3O(7-x) compound during long term storage, and burn out characteristics. While many questions were answered with respect to the interfacial reactions between YBa2Cu3O(7-x) and carbon, much work is still necessary to improve the quality of the sintered material if the fibers produced are to be incorporated into useful composites or cables. Additional research is necessary to evaluate quality of the barrier layer during long soakings at the peak temperature; adjust the firing schedule to avoid microcracking and improve densification; and increase the solids loading in the superconductive suspension to decrease porosity.

  19. Designed amyloid fibers as materials for selective carbon dioxide capture.

    PubMed

    Li, Dan; Furukawa, Hiroyasu; Deng, Hexiang; Liu, Cong; Yaghi, Omar M; Eisenberg, David S

    2014-01-01

    New materials capable of binding carbon dioxide are essential for addressing climate change. Here, we demonstrate that amyloids, self-assembling protein fibers, are effective for selective carbon dioxide capture. Solid-state NMR proves that amyloid fibers containing alkylamine groups reversibly bind carbon dioxide via carbamate formation. Thermodynamic and kinetic capture-and-release tests show the carbamate formation rate is fast enough to capture carbon dioxide by dynamic separation, undiminished by the presence of water, in both a natural amyloid and designed amyloids having increased carbon dioxide capacity. Heating to 100 °C regenerates the material. These results demonstrate the potential of amyloid fibers for environmental carbon dioxide capture.

  20. Voltammetric detection of biological molecules using chopped carbon fiber.

    PubMed

    Sugawara, Kazuharu; Yugami, Asako; Kojima, Akira

    2010-01-01

    Voltammetric detection of biological molecules was carried out using chopped carbon fibers produced from carbon fiber reinforced plastics that are biocompatible and inexpensive. Because chopped carbon fibers normally are covered with a sizing agent, they are difficult to use as an electrode. However, when the surface of a chopped carbon fiber was treated with ethanol and hydrochloric acid, it became conductive. To evaluate the functioning of chopped carbon fibers, voltammetric measurements of [Fe(CN)(6)](3-) were carried out. Redoxes of FAD, ascorbic acid and NADH as biomolecules were recorded using cyclic voltammetry. The sizing agents used to bundle the fibers were epoxy, polyamide and polyurethane resins. The peak currents were the greatest when using the chopped carbon fibers that were created with epoxy resins. When the electrode response of the chopped carbon fibers was compared with that of a glassy carbon electrode, the peak currents and the reversibility of the electrode reaction were sufficient. Therefore, the chopped carbon fibers will be useful as disposable electrodes for the sensing of biomolecules. PMID:20953048

  1. Polarization dependence of laser interaction with carbon fibers and CFRP.

    PubMed

    Freitag, Christian; Weber, Rudolf; Graf, Thomas

    2014-01-27

    A key factor for laser materials processing is the absorptivity of the material at the laser wavelength, which determines the fraction of the laser energy that is coupled into the material. Based on the Fresnel equations, a theoretical model is used to determine the absorptivity for carbon fiber fabrics and carbon fiber reinforced plastics (CFRP). The surface of each carbon fiber is considered as multiple layers of concentric cylinders of graphite. With this the optical properties of carbon fibers and their composites can be estimated from the well-known optical properties of graphite.

  2. Voltammetric detection of biological molecules using chopped carbon fiber.

    PubMed

    Sugawara, Kazuharu; Yugami, Asako; Kojima, Akira

    2010-01-01

    Voltammetric detection of biological molecules was carried out using chopped carbon fibers produced from carbon fiber reinforced plastics that are biocompatible and inexpensive. Because chopped carbon fibers normally are covered with a sizing agent, they are difficult to use as an electrode. However, when the surface of a chopped carbon fiber was treated with ethanol and hydrochloric acid, it became conductive. To evaluate the functioning of chopped carbon fibers, voltammetric measurements of [Fe(CN)(6)](3-) were carried out. Redoxes of FAD, ascorbic acid and NADH as biomolecules were recorded using cyclic voltammetry. The sizing agents used to bundle the fibers were epoxy, polyamide and polyurethane resins. The peak currents were the greatest when using the chopped carbon fibers that were created with epoxy resins. When the electrode response of the chopped carbon fibers was compared with that of a glassy carbon electrode, the peak currents and the reversibility of the electrode reaction were sufficient. Therefore, the chopped carbon fibers will be useful as disposable electrodes for the sensing of biomolecules.

  3. Radiation effects on carbon fiber reinforced thermoplastics

    SciTech Connect

    Sasuga, Tsuneo; Udagawa, Akira; Seguchi, Tadao

    1993-12-31

    Polyether-ether-ketone (PEEK) and a newly developed thermoplastic polyimide ``new-TPI`` were applied to carbon fiber reinforced plastic (CFRP) as a matrix resin. PEEK and new-TPI showed excellent resistance over 50 MGy to electron irradiation and the crosslinking proceeded predominantly by irradiation. The changes in mechanical properties induced by electron irradiation of the CFRP with the two resins were examined at various temperatures. The flexural strength and modulus measured at {minus}196 and 25{degree}C were scarcely affected up to 120 MGy and both the values measured at high temperature were increased with dose.

  4. Carbon fibers from electrospun polymeric phenolic resin precursors

    NASA Astrophysics Data System (ADS)

    Gee, Diane L.

    This dissertation presents a technique for producing carbon fibers of nano- to micro-sized dimension by utilizing a non-conventional fiber spinning approach with refractory polymers, followed by post-processing steps, to create new carbon materials with distinctive chemical/physical property characteristics. Phenolic resins, novolak and resole, are selected for this study because of their low cost, marketability, environmental friendliness, and high char yield upon pyrolysis. The new carbon fibers are at least an order of magnitude smaller than their conventionally processed counterpart, and possess significant advantages. Phenolic resin fibers, consisting of a blend of novolak and resole, are generated via electrospinning and are subsequently cured and pyrolyzed at temperatures from 800°C to 2000°C to form carbon fibers having diameters of ˜1 mum. Fiber analysis by scanning electron microscopy confirms that the morphology generated during the electrospinning processing is retained throughout the curing and carbonization processes. X-ray diffraction suggests the presence of highly graphitized carbon, which is further validated by high-resolution transmission electron microscopy (HRTEM) analysis. There is evidence of crystalline graphite, which may have nucleated on aligned sheets presence on the fiber surface. The physical characteristics of electrospun fibers are contrary to those exhibited by pyrolyzed phenolic resins, which fall into the classification of non-graphitizing. It is likely that the thin electrospun fibers offer a template that encourages ordering not usually seen in thicker fibers or bulk samples of carbonized phenolic resins.

  5. On the nature of interface of carbon nanotube coated carbon fibers with different polymers

    NASA Astrophysics Data System (ADS)

    Singh Bedi, Harpreet; Padhee, Srikant S.; Agnihotri, Prabhat K.

    2016-07-01

    Experimental investigations are carried out to analyse the wetting behaviour of carbon nanotube (CNT) coated carbon fiber to determine their suitability to process carbon nanotube coated carbon fiber/polymer multiscale composites for structural applications. To overcome the problem of agglomeration, CNTs are grown directly on the surface of carbon fibers as well as fabric using thermal chemical vapour deposition (CVD) technique. The term multiscale is used because different reinforcement mechanisms operate at the scale of long fibers and CNTs which are of few micrometers in length. The load carrying capacity of these multiscale composites critically depends on the efficiency and extent of load transfer from low strength matrix to high strength fiber which in turn depends on the interfacial strength between CNT coated carbon fiber and polymer matrix. A systematic analysis of wetting behaviour of CNT coated carbon fiber with epoxy and polyester matrix is carried out in this study. It is shown that CNT coated carbon fibers as well as fabric show better wettability with epoxy matrix as compared to polyester matrix. This results in stronger interface of CNT coated carbon fiber with epoxy as compared to polyester in multiscale composite system. A similar observation is made in nanoindentation testing of single fiber multiscale composites processed with epoxy and polyester matrix. In addition, it is observed that wettability, interfacial strength and average properties of CNT coated carbon fiber/polymer composites are a function of CNT density on the surface of carbon fibers.

  6. Experimental Behavior of Carbon Fiber Reinforced Isolators

    SciTech Connect

    Russo, Gaetano; Pauletta, Margherita; Cortesia, Andrea; Dal Bianco, Alberto

    2008-07-08

    This paper describes an investigation on the experimental behavior of innovative elastomeric isolators reinforced by carbon fiber fabrics. These fabrics are very much lighter than steel plates used in conventional isolators and able to transfer to the adjacent elastomer layers tangential stresses adequate to oppose the transversal deformation of rubber under vertical loads. The isolators are not bonded to the sub- and super-structure (elimination of the steel end-plates), hence their weight and cost are reduced. The experimental investigation is carried out on small-scale isolator prototypes reinforced by quadridirectional carbon fiber fabrics. The isolators are subjected to the following qualification tests prescribed by the Italian Code 'Ordinanza 3274' for steel reinforced isolators: 1) 'Static assessment of the compression stiffness'; 2) 'Static assessment of the shear modulus G'; 3) 'Dynamic assessment of the dynamic shear modulus G{sub din} and of the damping coefficient {xi}; 4) 'Assessment of the G{sub din}-{gamma} and {xi}-{gamma} diagrams by means of dynamic tests'; 5) 'Assessment of creep characteristics'; 6) 'Evaluation of the capacity of sustaining at least 10 cycles'. As a result of the tests, the isolators survived large shear strains, comparable to those expected for conventional isolators.

  7. Liquid crystal polyester-carbon fiber composites

    NASA Technical Reports Server (NTRS)

    Chung, T. S.

    1984-01-01

    Liquid crystal polymers (LCP) have been developed as a thermoplastic matrix for high performance composites. A successful melt impregnation method has been developed which results in the production of continuous carbon fiber (CF) reinforced LCP prepreg tape. Subsequent layup and molding of prepreg into laminates has yielded composites of good quality. Tensile and flexural properties of LCP/CF composites are comparable to those of epoxy/CF composites. The LCP/CF composites have better impact resistance than the latter, although epoxy/CF composites possess superior compression and shear strength. The LCP/CF composites have good property retention until 200 F (67 % of room temperature value). Above 200 F, mechanical properties decrease significantly. Experimental results indicate that the poor compression and shear strength may be due to the poor interfacial adhesion between the matrix and carbon fiber as adequate toughness of the LCP matrix. Low mechanical property retention at high temperatures may be attributable to the low beta-transition temperature (around 80 C) of the LCP matrix material.

  8. Dissemination, resuspension, and filtration of carbon fibers. [aircraft fires

    NASA Technical Reports Server (NTRS)

    Elber, W.

    1980-01-01

    Carbon fiber transport was studied using mathematical models established for other pollution problems. It was demonstrated that resuspension is not a major factor contributing to the risk. Filtration and fragmentation tests revealed that fiber fragmentation shifts the fiber spectrum to shorter mean lengths in high velocity air handling systems.

  9. Characterization and Oxidation Behavior of Rayon-Derived Carbon Fibers

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan; Hull, David

    2010-01-01

    Rayon-derived fibers are the central constituent of reinforced carbon/ carbon (RCC) composites. Optical, scanning electron, and transmission electron microscopy were used to characterize the as-fabricated fibers and the fibers after oxidation. Oxidation rates were measured with weight loss techniques in air and oxygen. The as-received fibers are approximately 10 micron in diameter and characterized by grooves or crenulations around the edges. Below 800 C, in the reaction-controlled region, preferential attack began in the crenulations and appeared to occur down fissures in the fibers.

  10. Carbon nanowalls grown by microwave plasma enhanced chemical vapor deposition during the carbonization of polyacrylonitrile fibers

    NASA Astrophysics Data System (ADS)

    Li, Jiangling; Su, Shi; Zhou, Lei; Kundrát, Vojtěch; Abbot, Andrew M.; Mushtaq, Fajer; Ouyang, Defang; James, David; Roberts, Darren; Ye, Haitao

    2013-01-01

    We used microwave plasma enhanced chemical vapor deposition (MPECVD) to carbonize an electrospun polyacrylonitrile (PAN) precursor to form carbon fibers. Scanning electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy were used to characterize the fibers at different evolution stages. It was found that MPECVD-carbonized PAN fibers do not exhibit any significant change in the fiber diameter, whilst conventionally carbonized PAN fibers show a 33% reduction in the fiber diameter. An additional coating of carbon nanowalls (CNWs) was formed on the surface of the carbonized PAN fibers during the MPECVD process without the assistance of any metallic catalysts. The result presented here may have a potential to develop a novel, economical, and straightforward approach towards the mass production of carbon fibrous materials containing CNWs.

  11. Carbon nanowalls grown by microwave plasma enhanced chemical vapor deposition during the carbonization of polyacrylonitrile fibers

    SciTech Connect

    Li Jiangling; Su Shi; Kundrat, Vojtech; Abbot, Andrew M.; Ye, Haitao; Zhou Lei; Mushtaq, Fajer; Ouyang Defang; James, David; Roberts, Darren

    2013-01-14

    We used microwave plasma enhanced chemical vapor deposition (MPECVD) to carbonize an electrospun polyacrylonitrile (PAN) precursor to form carbon fibers. Scanning electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy were used to characterize the fibers at different evolution stages. It was found that MPECVD-carbonized PAN fibers do not exhibit any significant change in the fiber diameter, whilst conventionally carbonized PAN fibers show a 33% reduction in the fiber diameter. An additional coating of carbon nanowalls (CNWs) was formed on the surface of the carbonized PAN fibers during the MPECVD process without the assistance of any metallic catalysts. The result presented here may have a potential to develop a novel, economical, and straightforward approach towards the mass production of carbon fibrous materials containing CNWs.

  12. Process for the manufacture of carbon or graphite fibers

    NASA Technical Reports Server (NTRS)

    Overhoff, D.; Winkler, E.; Mueller, D.

    1979-01-01

    Carbon or graphite fibers are manufactured by heating polyacrylonitrile fiber materials in various solutions and gases. They are characterized in that the materials are heated to temperatures from 150 to 300 C in a solution containing one or more acids from the group of carbonic acids, sulfonic acids, and/or phenols. The original molecular orientation of the fibers is preserved by the cyclization that occurs before interlacing, which gives very strong and stiff carbon or graphite fibers without additional high temperature stretching treatments.

  13. Carbon-fiber low-voltage electron guns

    SciTech Connect

    Drori, R.; Jerby, E.

    1995-12-31

    Carbon-fiber cathodes am used in cold electron-guns in our laboratory. They operate in low-voltage (< 10 kV) free-electron maser and cyclotron-resonance maser experiments. The paper presents I-V characteristics of various carbon-fiber electron-guns and show results of the corresponding maser experiments.

  14. Structure and growth process of vapor-grown carbon fibers

    NASA Technical Reports Server (NTRS)

    Koyama, T.; Endo, M.

    1983-01-01

    The structure, effect of heat, and growth process of vapor-grown carbon fibers are investigated. The growth process of the carbon fibers could be divided into three stages; nucleation, elongation, and thickening processes. Also, a multi-layered structure can be produced as well as graphitization.

  15. High efficient preparation of carbon nanotube-grafted carbon fibers with the improved tensile strength

    NASA Astrophysics Data System (ADS)

    Fan, Wenxin; Wang, Yanxiang; Wang, Chengguo; Chen, Jiqiang; Wang, Qifen; Yuan, Yan; Niu, Fangxu

    2016-02-01

    An innovative technique has been developed to obtain the uniform catalyst coating on continuously moving carbon fibers. Carbon nanotube (CNT)-grafted carbon fibers with significantly improved tensile strength have been succeeded to produce by using chemical vapor deposition (CVD) when compared to the tensile strength of untreated carbon fibers. The critical requirements for preparation of CNT-grafted carbon fibers with high tensile strength have been found, mainly including (i) the obtainment of uniform coating of catalyst particles with small particle size, (ii) the low catalyst-induced and mechano-chemical degradation of carbon fibers, and (iii) the high catalyst activity which could facilitate the healing and strengthening of carbon fibers during the growth of CNTs. The optimum growth temperature was found to be about 500 °C, and the optimum catalyst is Ni due to its highest activity, there is a pronounced increase of 10% in tensile strength of carbon fibers after CNT growth at 500 °C by using Ni catalyst. Based on the observation from HRTEM images, a healing and crosslink model of neighboring carbon crystals by CNTs has been formulated to reveal the main reason that causes an increase in tensile strength of carbon fibers after the growth of CNTs. Such results have provided the theoretical and experimental foundation for the large-scale preparation of CNT-grafted carbon fibers with the improved tensile strength, significantly promoting the development of CNT-grafted carbon fiber reinforced polymer composites.

  16. Thermal Properties of Hybrid Carbon Nanotube/Carbon Fiber Polymer

    NASA Technical Reports Server (NTRS)

    Kang, Jin Ho; Cano, Roberto J.; Luong, Hoa; Ratcliffe, James G.; Grimsley, Brian W.; Siochi, Emilie J.

    2016-01-01

    Carbon fiber reinforced polymer (CFRP) composites possess many advantages for aircraft structures over conventional aluminum alloys: light weight, higher strength- and stiffness-to-weight ratio, and low life-cycle maintenance costs. However, the relatively low thermal and electrical conductivities of CFRP composites are deficient in providing structural safety under certain operational conditions such as lightning strikes. One possible solution to these issues is to interleave carbon nanotube (CNT) sheets between conventional carbon fiber (CF) composite layers. However, the thermal and electrical properties of the orthotropic hybrid CNT/CF composites have not been fully understood. In this study, hybrid CNT/CF polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel (Registered Trademark) IM7/8852 prepreg. The CNT sheets were infused with a 5% solution of a compatible epoxy resin prior to composite fabrication. Orthotropic thermal and electrical conductivities of the hybrid polymer composites were evaluated. The interleaved CNT sheets improved the in-plane thermal conductivity of the hybrid composite laminates by about 400% and the electrical conductivity by about 3 orders of magnitude.

  17. Multifunctional Hybrid Carbon Nanotube/Carbon Fiber Polymer Composites

    NASA Technical Reports Server (NTRS)

    Kang, Jin Ho; Cano, Roberto J.; Ratcliffe, James G.; Luong, Hoa; Grimsley, Brian W.; Siochi, Emilie J.

    2016-01-01

    For aircraft primary structures, carbon fiber reinforced polymer (CFRP) composites possess many advantages over conventional aluminum alloys due to their light weight, higher strengthand stiffness-to-weight ratio, and low life-cycle maintenance costs. However, the relatively low electrical and thermal conductivities of CFRP composites fail to provide structural safety in certain operational conditions such as lightning strikes. Despite several attempts to solve these issues with the addition of carbon nanotubes (CNT) into polymer matrices, and/or by interleaving CNT sheets between conventional carbon fiber (CF) composite layers, there are still interfacial problems that exist between CNTs (or CF) and the resin. In this study, hybrid CNT/CF polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel® IM7/8852 prepreg. Resin concentrations from 1 wt% to 50 wt% were used to infuse the CNT sheets prior to composite fabrication. The interlaminar properties of the resulting hybrid composites were characterized by mode I and II fracture toughness testing (double cantilever beam and end-notched flexure test). Fractographical analysis was performed to study the effect of resin concentration. In addition, multi-directional physical properties like thermal conductivity of the orthotropic hybrid polymer composite were evaluated. Interleaving CNT sheets significantly improved the in-plane (axial and perpendicular direction of CF alignment) thermal conductivity of the hybrid composite laminates by 50 - 400%.

  18. Preliminary experimental study of a carbon fiber array cathode

    NASA Astrophysics Data System (ADS)

    Li, An-kun; Fan, Yu-wei

    2016-08-01

    The preliminary experimental results of a carbon fiber array cathode for the magnetically insulated transmission line oscillator (MILO) operations are reported. When the diode voltage and diode current were 480 kV and 44 kA, respectively, high-power microwaves with a peak power of about 3 GW and a pulse duration of about 60 ns were obtained in a MILO device with the carbon fiber array cathode. The preliminary experimental results show that the shot-to-shot reproducibility of the diode current and the microwave power is stable until 700 shots. No obvious damage or deterioration can be observed in the carbon fiber surface morphology after 700 shots. Moreover, the cathode performance has no observable deterioration after 700 shots. In conclusion, the maintain-free lifetime of the carbon fiber array cathode is more than 700 shots. In this way, this carbon fiber array cathode offers a potential replacement for the existing velvet cathode.

  19. Graphitized-carbon fiber/carbon char fuel

    SciTech Connect

    Cooper, John F.

    2007-08-28

    A method for recovery of intact graphitic fibers from fiber/polymer composites is described. The method comprises first pyrolyzing the graphite fiber/polymer composite mixture and then separating the graphite fibers by molten salt electrochemical oxidation.

  20. Graphene nanoribbons as an advanced precursor for making carbon fiber.

    PubMed

    Xiang, Changsheng; Behabtu, Natnael; Liu, Yaodong; Chae, Han Gi; Young, Colin C; Genorio, Bostjan; Tsentalovich, Dmitri E; Zhang, Chenguang; Kosynkin, Dmitry V; Lomeda, Jay R; Hwang, Chih-Chau; Kumar, Satish; Pasquali, Matteo; Tour, James M

    2013-02-26

    Graphene oxide nanoribbons (GONRs) and chemically reduced graphene nanoribbons (crGNRs) were dispersed at high concentrations in chlorosulfonic acid to form anisotropic liquid crystal phases. The liquid crystal solutions were spun directly into hundreds of meters of continuous macroscopic fibers. The relationship of fiber morphology to coagulation bath conditions was studied. The effects of colloid concentration, annealing temperature, spinning air gap, and pretension during annealing on the fibers' performance were also investigated. Heat treatment of the as-spun GONR fibers at 1500 °C produced thermally reduced graphene nanoribbon (trGNR) fibers with a tensile strength of 378 MPa, Young's modulus of 36.2 GPa, and electrical conductivity of 285 S/cm, which is considerably higher than that in other reported graphene-derived fibers. This better trGNR fiber performance was due to the air gap spinning and annealing with pretension that produced higher molecular alignment within the fibers, as determined by X-ray diffraction and scanning electron microscopy. The specific modulus of trGNR fibers is higher than that of the commercial general purpose carbon fibers and commonly used metals such as Al, Cu, and steel. The properties of trGNR fibers can be further improved by optimizing the spinning conditions with higher draw ratio, annealing conditions with higher pretensions, and using longer flake GONRs. This technique is a new high-carbon-yield approach to make the next generation carbon fibers based on solution-based liquid crystal phase spinning. PMID:23339339

  1. Graphene nanoribbons as an advanced precursor for making carbon fiber.

    PubMed

    Xiang, Changsheng; Behabtu, Natnael; Liu, Yaodong; Chae, Han Gi; Young, Colin C; Genorio, Bostjan; Tsentalovich, Dmitri E; Zhang, Chenguang; Kosynkin, Dmitry V; Lomeda, Jay R; Hwang, Chih-Chau; Kumar, Satish; Pasquali, Matteo; Tour, James M

    2013-02-26

    Graphene oxide nanoribbons (GONRs) and chemically reduced graphene nanoribbons (crGNRs) were dispersed at high concentrations in chlorosulfonic acid to form anisotropic liquid crystal phases. The liquid crystal solutions were spun directly into hundreds of meters of continuous macroscopic fibers. The relationship of fiber morphology to coagulation bath conditions was studied. The effects of colloid concentration, annealing temperature, spinning air gap, and pretension during annealing on the fibers' performance were also investigated. Heat treatment of the as-spun GONR fibers at 1500 °C produced thermally reduced graphene nanoribbon (trGNR) fibers with a tensile strength of 378 MPa, Young's modulus of 36.2 GPa, and electrical conductivity of 285 S/cm, which is considerably higher than that in other reported graphene-derived fibers. This better trGNR fiber performance was due to the air gap spinning and annealing with pretension that produced higher molecular alignment within the fibers, as determined by X-ray diffraction and scanning electron microscopy. The specific modulus of trGNR fibers is higher than that of the commercial general purpose carbon fibers and commonly used metals such as Al, Cu, and steel. The properties of trGNR fibers can be further improved by optimizing the spinning conditions with higher draw ratio, annealing conditions with higher pretensions, and using longer flake GONRs. This technique is a new high-carbon-yield approach to make the next generation carbon fibers based on solution-based liquid crystal phase spinning.

  2. Shear transfer in concrete reinforced with carbon fibers

    NASA Astrophysics Data System (ADS)

    El-Mokadem, Khaled Mounir

    2001-10-01

    Scope and method of study. The research started with preliminary tests and studies on the behavior and effect of carbon fibers in different water solutions and mortar/concrete mixes. The research work investigated the use of CF in the production of concrete pipes and prestressed concrete double-tee sections. The research then focused on studying the effect of using carbon fibers on the direct shear transfer of sand-lightweight reinforced concrete push-off specimens. Findings and conclusions. In general, adding carbon fibers to concrete improved its tensile characteristics but decreased its compressive strength. The decrease in compressive strength was due to the decrease in concrete density as fibers act as three-dimensional mesh that entrapped air. The decrease in compressive strength was also due to the increase in the total surface area of non-cementitious material in the concrete. Sand-lightweight reinforced concrete push-off specimens with carbon fibers had lower shear carrying capacity than those without carbon fibers for the same cement content in the concrete. Current building codes and specifications estimate the shear strength of concrete as a ratio of the compressive strength. If applying the same principals then the ratio of shear strength to compressive strength for concrete reinforced with carbon fibers is higher than that for concrete without carbon fibers.

  3. Surface characterization of LDEF carbon fiber/polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Grammer, Holly L.; Wightman, James P.; Young, Philip R.; Slemp, Wayne S.

    1995-01-01

    XPS (x-ray photoelectron spectroscopy) and SEM (scanning electron microscopy) analysis of both carbon fiber/epoxy matrix and carbon fiber/polysulfone matrix composites revealed significant changes in the surface composition as a result of exposure to low-earth orbit. The carbon 1s curve fit XPS analysis in conjunction with the SEM photomicrographs revealed significant erosion of the polymer matrix resins by atomic oxygen to expose the carbon fibers of the composite samples. This erosion effect on the composites was seen after 10 months in orbit and was even more obvious after 69 months.

  4. Carbon nanotube reinforced polyacrylonitrile and poly(etherketone) fibers

    NASA Astrophysics Data System (ADS)

    Jain, Rahul

    The graphitic nature, continuous structure, and high mechanical properties of carbon nanotubes (CNTs) make them good candidate for reinforcing polymer fiber. The different types of CNTs including single-wall carbon nanotubes (SWNTs), few-wall carbon nanotubes (FWNTs), and multi-wall carbon nanotubes (MWNTs), and carbon nanofibers (CNFs) differ in terms of their diameter and number of graphitic walls. The desire has been to increase the concentration of CNTs as much as possible to make next generation multi-functional materials. The work in this thesis is mainly focused on MWNT and CNF reinforced polyacrylonitrile (PAN) composite fibers, and SWNT, FWNT, and MWNT reinforced poly(etherketone) (PEK) composite fibers. To the best of our knowledge, this is the first study to report the spinning of 20% MWNT or 30% CNF reinforced polymer fiber spun using conventional fiber spinning. Also, this is the first study to report the PEK/CNT composite fibers. The fibers were characterized for their thermal, tensile, mechanical, and dynamic mechanical properties. The fiber structure and morphology was studied using WAXD and SEM. The effect of two-stage heat drawing, sonication time for CNF dispersion, fiber drying temperature, and molecular weight of PAN was also studied. Other challenges associated with processing high concentrations of solutions for making composite fibers have been identified and reported. The effect of CNT diameter and concentration on fiber spinnability and electrical conductivity of composite fiber have also been studied. This work suggests that CNT diameter controls the maximum possible concentration of CNTs in a composite fiber. The results show that by properly choosing the type of CNT, length of CNTs, dispersion of CNTs, fiber spinning method, fiber draw ratio, and type of polymer, one can get electrically conducting fibers with wide range of conductivities for different applications. The PEK based control and composite fibers possess high thermal

  5. RADIATION EFFECTS ON EPOXY CARBON FIBER COMPOSITE

    SciTech Connect

    Hoffman, E

    2008-05-30

    Carbon fiber-reinforced bisphenol-A epoxy matrix composite was evaluated for gamma radiation resistance. The composite was exposed to total gamma doses of 50, 100, and 200 Mrad. Irradiated and baseline samples were tested for tensile strength, hardness and evaluated using FTIR (Fourier transform infrared) spectroscopy and DSC (differential scanning calorimetry) for structural changes. Scanning electron microscopy was used to evaluate microstructural behavior. Mechanical testing of the composite bars revealed no apparent change in modulus, strain to failure, or fracture strength after exposures. However, testing of only the epoxy matrix revealed changes in hardness, thermal properties, and FTIR results with increasing gamma irradiation. The results suggest the epoxy within the composite can be affected by exposure to gamma irradiation.

  6. Waste polyvinylchloride derived pitch as a precursor to develop carbon fibers and activated carbon fibers.

    PubMed

    Qiao, W M; Yoon, S H; Mochida, I; Yang, J H

    2007-01-01

    Polyvinylchloride (PVC) was successfully recycled through the solvent extraction from waste pipe with an extraction yield of ca. 86%. The extracted PVC was pyrolyzed by a two-stage process (260 and 410 degrees C) to obtain free-chlorine PVC based pitch through an effective removal of chlorine from PVC during the heat-treatment. As-prepared pitch (softening point: 220 degrees C) was spun, stabilized, carbonized into carbon fibers (CFs), and further activated into activated carbon fibers (ACFs) in a flow of CO2. As-prepared CFs show comparable mechanical properties to commercial CFs, whose maximum tensile strength and modulus are 862 MPa and 62 GPa, respectively. The resultant ACFs exhibit a high surface area of 1200 m2/g, narrow pore size distribution and a low oxygen content of 3%. The study provides an effective insight to recycle PVC from waste PVC and develop a carbon precursor for high performance carbon materials such as CFs and ACFs. PMID:17157493

  7. Aligning carbon fibers in micro-extruded composite ink

    NASA Astrophysics Data System (ADS)

    Mahajan, Chaitanya G.

    Direct write processes include a wide range of additive manufacturing techniques with the ability to fabricate structures directly onto planar and non-planar surfaces. Most additive manufacturing techniques use unreinforced polymers to produce parts. By adding carbon fiber as a reinforcing material, properties such as mechanical strength, electrical conductivity, and thermal conductivity can be enhanced. Carbon fibers can be long and continuous, or short and discontinuous. The strength of carbon fiber composite parts is greatly increased when the fibers are preferentially aligned. This research focuses on increasing the strength of additively manufactured parts reinforced using discontinuous carbon fibers that have been aligned during the micro extrusion process. A design of experiments (DOE) approach was used to identify significant process parameters affecting fiber alignment. Factors such as the length of carbon fibers, nozzle diameter, fiber loading fraction, air pressure, translational speed and standoff distance were considered. A two dimensional Fast Fourier Transform (2D FFT) was used to quantify the degree of fiber alignment in the extruded composite inks. ImageJ software supported by an oval profile plugin was used with micrographs of printed samples to obtain the carbon fiber alignment values. The optimal value for the factors was derived by identifying the significant main and interaction effects. Based on the results of the DOE, tensile test samples were printed with fibers aligned parallel and perpendicular to the tensile axis. A standard test method for tensile properties of plastic revealed that the extruded parts with fibers aligned along the tensile axis were better in tensile strength and modulus.

  8. Carbon nanotubes on carbon fibers: Synthesis, structures and properties

    NASA Astrophysics Data System (ADS)

    Zhang, Qiuhong

    The interface between carbon fibers (CFs) and the resin matrix in traditional high performance composites is characterized by a large discontinuity in mechanical, electrical, and thermal properties which can cause inefficient energy transfer. Due to the exceptional properties of carbon nanotubes (CNTs), their growth at the surface of carbon fibers is a promising approach to controlling interfacial interactions and achieving the enhanced bulk properties. However, the reactive conditions used to grow carbon nanotubes also have the potential to introduce defects that can degrade the mechanical properties of the carbon fiber (CF) substrate. In this study, using thermal chemical vapor deposition (CVD) method, high density multi-wall carbon nanotubes have been successfully synthesized directly on PAN-based CF surface without significantly compromising tensile properties. The influence of CVD growth conditions on the single CF tensile properties and carbon nanotube (CNT) morphology was investigated. The experimental results revealed that under high temperature growth conditions, the tensile strength of CF was greatly decreased at the beginning of CNT growth process with the largest decrease observed for sized CFs. However, the tensile strength of unsized CFs with CNT was approximately the same as the initial CF at lower growth temperature. The interfacial shear strength of CNT coated CF (CNT/CF) in epoxy was studied by means of the single-fiber fragmentation test. Results of the test indicate an improvement in interfacial shear strength with the addition of a CNT coating. This improvement can most likely be attributed to an increase in the interphase yield strength as well as an improvement in interfacial adhesion due to the presence of the nanotubes. CNT/CF also offers promise as stress and strain sensors in CF reinforced composite materials. This study investigates fundamental mechanical and electrical properties of CNT/CF using nanoindentation method by designed

  9. Strong, conductive carbon nanotube fibers as efficient hole collectors.

    PubMed

    Jia, Yi; Li, Xiao; Li, Peixu; Wang, Kunlin; Cao, Anyuan; Wei, Jinquan; Zhu, Hongwei; Wu, Dehai

    2012-02-17

    We present the photovoltaic properties of heterojunctions made from single-walled carbon nanotube (SWNT) fibers and n-type silicon wafers. The use of the opaque SWNT fiber allows photo-generated holes to transport along the axis direction of the fiber. The heterojunction solar cells show conversion efficiencies of up to 3.1% (actual) and 10.6% (nominal) at AM1.5 condition. In addition, the use of strong, environmentally benign carbon nanotube fibers provides excellent structural stability of the photovoltaic devices.

  10. Strong, conductive carbon nanotube fibers as efficient hole collectors

    PubMed Central

    2012-01-01

    We present the photovoltaic properties of heterojunctions made from single-walled carbon nanotube (SWNT) fibers and n-type silicon wafers. The use of the opaque SWNT fiber allows photo-generated holes to transport along the axis direction of the fiber. The heterojunction solar cells show conversion efficiencies of up to 3.1% (actual) and 10.6% (nominal) at AM1.5 condition. In addition, the use of strong, environmentally benign carbon nanotube fibers provides excellent structural stability of the photovoltaic devices. PMID:22340519

  11. [Carbon fiber-reinforced plastics as implant materials].

    PubMed

    Bader, R; Steinhauser, E; Rechl, H; Siebels, W; Mittelmeier, W; Gradinger, R

    2003-01-01

    Carbon fiber-reinforced plastics have been used clinically as an implant material for different applications for over 20 years.A review of technical basics of the composite materials (carbon fibers and matrix systems), fields of application,advantages (e.g., postoperative visualization without distortion in computed and magnetic resonance tomography), and disadvantages with use as an implant material is given. The question of the biocompatibility of carbon fiber-reinforced plastics is discussed on the basis of experimental and clinical studies. Selected implant systems made of carbon composite materials for treatments in orthopedic surgery such as joint replacement, tumor surgery, and spinal operations are presented and assessed. Present applications for carbon fiber reinforced plastics are seen in the field of spinal surgery, both as cages for interbody fusion and vertebral body replacement.

  12. An investigation of carbon fiber/polyphenylene sulfide adhesion

    SciTech Connect

    Fisher, G.S.; Drzal, L.T.

    1996-12-31

    The level of adhesion between reinforcing fibers and a thermoplastic matrix can have a strong effect on composite mechanical properties. In composites of polyphenylene sulfide (PPS) with carbon fibers, Phillips Petroleum Company has reported an increase in transverse tensile strength from 30 MPa to 74 MPa and an increase in transverse flexural strength from 44 to 141 MPa when extrusion grade PPS resin is replaced with a composite grade resin. Since transverse composite properties are particularly sensitive to adhesion, it was suspected that improved fiber/matrix adhesion could be responsible for the improved mechanical properties. Several factors can affect the adhesion between carbon fibers and a semicrystalline thermoplastic such as PPS. These factors include fiber surface structure and chemistry, adsorption of matrix onto fibers, chemical bonding between fiber and matrix, and morphology of the matrix near the fibers. The objectives of this study were to determine the interfacial shear strengths of several types of carbon fibers with both grades of PPS and to determine which factors affect fiber/matrix adhesion. This will allow the authors to determine whether the differences in composite mechanical properties can be correlated to different levels of adhesion and to identify the key factor(s) that lead to any differences in adhesion.

  13. The Tensile Behavior of High-Strength Carbon Fibers.

    PubMed

    Langston, Tye

    2016-08-01

    Carbon fibers exhibit exceptional properties such as high stiffness and specific strength, making them excellent reinforcements for composite materials. However, it is difficult to directly measure their tensile properties and estimates are often obtained by tensioning fiber bundles or composites. While these macro scale tests are informative for composite design, their results differ from that of direct testing of individual fibers. Furthermore, carbon filament strength also depends on other variables, including the test length, actual fiber diameter, and material flaw distribution. Single fiber tensile testing was performed on high-strength carbon fibers to determine the load and strain at failure. Scanning electron microscopy was also conducted to evaluate the fiber surface morphology and precisely measure each fiber's diameter. Fiber strength was found to depend on the test gage length and in an effort to better understand the overall expected performance of these fibers at various lengths, statistical weak link scaling was performed. In addition, the true Young's modulus was also determined by taking the system compliance into account. It was found that all properties (tensile strength, strain to failure, and Young's modulus) matched very well with the manufacturers' reported values at 20 mm gage lengths, but deviated significantly at other lengths.

  14. The Tensile Behavior of High-Strength Carbon Fibers.

    PubMed

    Langston, Tye

    2016-08-01

    Carbon fibers exhibit exceptional properties such as high stiffness and specific strength, making them excellent reinforcements for composite materials. However, it is difficult to directly measure their tensile properties and estimates are often obtained by tensioning fiber bundles or composites. While these macro scale tests are informative for composite design, their results differ from that of direct testing of individual fibers. Furthermore, carbon filament strength also depends on other variables, including the test length, actual fiber diameter, and material flaw distribution. Single fiber tensile testing was performed on high-strength carbon fibers to determine the load and strain at failure. Scanning electron microscopy was also conducted to evaluate the fiber surface morphology and precisely measure each fiber's diameter. Fiber strength was found to depend on the test gage length and in an effort to better understand the overall expected performance of these fibers at various lengths, statistical weak link scaling was performed. In addition, the true Young's modulus was also determined by taking the system compliance into account. It was found that all properties (tensile strength, strain to failure, and Young's modulus) matched very well with the manufacturers' reported values at 20 mm gage lengths, but deviated significantly at other lengths. PMID:27278219

  15. Activated carbon fiber composite material and method of making

    DOEpatents

    Burchell, Timothy D.; Weaver, Charles E.; Chilcoat, Bill R.; Derbyshire, Frank; Jagtoyen, Marit

    2000-01-01

    An activated carbon fiber composite for separation and purification, or catalytic processing of fluids is described. The activated composite comprises carbon fibers rigidly bonded to form an open, permeable, rigid monolith capable of being formed to near-net-shape. Separation and purification of gases are effected by means of a controlled pore structure that is developed in the carbon fibers contained in the composite. The open, permeable structure allows the free flow of gases through the monolith accompanied by high rates of adsorption. By modification of the pore structure and bulk density the composite can be rendered suitable for applications such as gas storage, catalysis, and liquid phase processing.

  16. Activated carbon fiber composite material and method of making

    DOEpatents

    Burchell, Timothy D.; Weaver, Charles E.; Chilcoat, Bill R.; Derbyshire, Frank; Jagtoyen, Marit

    2001-01-01

    An activated carbon fiber composite for separation and purification, or catalytic processing of fluids is described. The activated composite comprises carbon fibers rigidly bonded to form an open, permeable, rigid monolith capable of being formed to near-net-shape. Separation and purification of gases are effected by means of a controlled pore structure that is developed in the carbon fibers contained in the composite. The open, permeable structure allows the free flow of gases through the monolith accompanied by high rates of adsorption. By modification of the pore structure and bulk density the composite can be rendered suitable for applications such as gas storage, catalysis, and liquid phase processing.

  17. Oxidation of Carbon Fibers in Water Vapor Studied

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth J.

    2003-01-01

    T-300 carbon fibers (BP Amoco Chemicals, Greenville, SC) are a common reinforcement for silicon carbide composite materials, and carbon-fiber-reinforced silicon carbide composites (C/SiC) are proposed for use in space propulsion applications. It has been shown that the time to failure for C/SiC in stressed oxidation tests is directly correlated with the fiber oxidation rate (ref. 1). To date, most of the testing of these fibers and composites has been conducted in oxygen or air environments; however, many components for space propulsion, such as turbopumps, combustors, and thrusters, are expected to operate in hydrogen and water vapor (H2/H2O) environments with very low oxygen contents. The oxidation rate of carbon fibers in conditions representative of space propulsion environments is, therefore, critical for predicting component lifetimes for real applications. This report describes experimental results that demonstrate that, under some conditions, lower oxidation rates of carbon fibers are observed in water vapor and H2/H2O environments than are found in oxygen or air. At the NASA Glenn Research Center, the weight loss of the fibers was studied as a function of water pressure, temperature, and gas velocity. The rate of carbon fiber oxidation was determined, and the reaction mechanism was identified.

  18. Polyethylenimine carbon nanotube fiber electrodes for enhanced detection of neurotransmitters.

    PubMed

    Zestos, Alexander G; Jacobs, Christopher B; Trikantzopoulos, Elefterios; Ross, Ashley E; Venton, B Jill

    2014-09-01

    Carbon nanotube (CNT)-based microelectrodes have been investigated as alternatives to carbon-fiber microelectrodes for the detection of neurotransmitters because they are sensitive, exhibit fast electron transfer kinetics, and are more resistant to surface fouling. Wet spinning CNTs into fibers using a coagulating polymer produces a thin, uniform fiber that can be fabricated into an electrode. CNT fibers formed in poly(vinyl alcohol) (PVA) have been used as microelectrodes to detect dopamine, serotonin, and hydrogen peroxide. In this study, we characterize microelectrodes with CNT fibers made in polyethylenimine (PEI), which have much higher conductivity than PVA-CNT fibers. PEI-CNT fibers have lower overpotentials and higher sensitivities than PVA-CNT fiber microelectrodes, with a limit of detection of 5 nM for dopamine. The currents for dopamine were adsorption controlled at PEI-CNT fiber microelectrodes, independent of scan repetition frequency, and stable for over 10 h. PEI-CNT fiber microelectrodes were resistant to surface fouling by serotonin and the metabolite interferant 5-hydroxyindoleacetic acid (5-HIAA). No change in sensitivity was observed for detection of serotonin after 30 flow injection experiments or after 2 h in 5-HIAA for PEI-CNT electrodes. The antifouling properties were maintained in brain slices when serotonin was exogenously applied multiple times or after bathing the slice in 5-HIAA. Thus, PEI-CNT fiber electrodes could be useful for the in vivo monitoring of neurochemicals. PMID:25117550

  19. Strong, light, multifunctional fibers of carbon nanotubes with ultrahigh conductivity.

    PubMed

    Behabtu, Natnael; Young, Colin C; Tsentalovich, Dmitri E; Kleinerman, Olga; Wang, Xuan; Ma, Anson W K; Bengio, E Amram; ter Waarbeek, Ron F; de Jong, Jorrit J; Hoogerwerf, Ron E; Fairchild, Steven B; Ferguson, John B; Maruyama, Benji; Kono, Junichiro; Talmon, Yeshayahu; Cohen, Yachin; Otto, Marcin J; Pasquali, Matteo

    2013-01-11

    Broader applications of carbon nanotubes to real-world problems have largely gone unfulfilled because of difficult material synthesis and laborious processing. We report high-performance multifunctional carbon nanotube (CNT) fibers that combine the specific strength, stiffness, and thermal conductivity of carbon fibers with the specific electrical conductivity of metals. These fibers consist of bulk-grown CNTs and are produced by high-throughput wet spinning, the same process used to produce high-performance industrial fibers. These scalable CNT fibers are positioned for high-value applications, such as aerospace electronics and field emission, and can evolve into engineered materials with broad long-term impact, from consumer electronics to long-range power transmission. PMID:23307737

  20. Potential release of fibers from burning carbon composites. [aircraft fires

    NASA Technical Reports Server (NTRS)

    Bell, V. L.

    1980-01-01

    A comprehensive experimental carbon fiber source program was conducted to determine the potential for the release of conductive carbon fibers from burning composites. Laboratory testing determined the relative importance of several parameters influencing the amounts of single fibers released, while large-scale aviation jet fuel pool fires provided realistic confirmation of the laboratory data. The dimensions and size distributions of fire-released carbon fibers were determined, not only for those of concern in an electrical sense, but also for those of potential interest from a health and environmental standpoint. Fire plume and chemistry studies were performed with large pool fires to provide an experimental input into an analytical modelling of simulated aircraft crash fires. A study of a high voltage spark system resulted in a promising device for the detection, counting, and sizing of electrically conductive fibers, for both active and passive modes of operation.

  1. Method for fabricating light weight carbon-bonded carbon fiber composites

    DOEpatents

    Wrenn, Jr., George E.; Abbatiello, Leonard A.; Lewis, Jr., John

    1989-01-01

    Ultralight carbon-bonded carbon fiber composites of densities in the range of about 0.04 to 0.10 grams per cubic centimeter are fabricated by forming an aqueous slurry of carbonaceous fibers which include carbonized fibers and 0-50 weight percent fugitive fibers and a particulate thermosetting resin precursor. The slurry is brought into contact with a perforated mandrel and the water is drained from the slurry through the perforations at a controlled flow rate of about 0.03 to 0.30 liters per minutes per square inch of mandrel surface. The deposited billet of fibers and resin precursor is heated to cure the resin precursor to bind the fibers together, removed from the mandrel, and then the resin and fugitive fibers, if any, are carbonized.

  2. Method for fabricating light weight carbon-bonded carbon fiber composites

    DOEpatents

    Wrenn, G.E. Jr.; Abbatiello, L.A.; Lewis, J. Jr.

    1987-06-17

    The invention is directed to the fabrication of ultralight carbon- bonded carbon fiber composites of densities in the range of about 0. 04 to 0.10 grams per cubic centimeter. The composites are fabricated by forming an aqueous slurry of carbonaceous fibers which include carbonized fibers and 0-50 weight percent fugitive fibers and a particulate thermosetting resin precursor. The slurry is brought into contact with a perforated mandrel and the water is drained from the slurry through the perforations at a controlled flow rate of about 0. 03 to 0.30 liters per minutes per square inch of a mandrel surface. The deposited billet of fibers and resin precursor is heated to cure the resin precursor to bind the fibers together, removed from the mandrel, and then the resin and fugitive fibers, if any, are carbonized.

  3. The surface properties of carbon fibers and their adhesion to organic polymers

    NASA Technical Reports Server (NTRS)

    Bascom, W. D.; Drzal, L. T.

    1987-01-01

    The state of knowledge of the surface properties of carbon fibers is reviewed, with emphasis on fiber/matrix adhesion in carbon fiber reinforced plastics. Subjects treated include carbon fiber structure and chemistry, techniques for the study of the fiber surface, polymer/fiber bond strength and its measurement, variations in polymer properties in the interphase, and the influence of fiber matrix adhesion on composite mechanical properties. Critical issues are summarized and search recommendations are made.

  4. Designed amyloid fibers as materials for selective carbon dioxide capture

    PubMed Central

    Li, Dan; Furukawa, Hiroyasu; Deng, Hexiang; Liu, Cong; Yaghi, Omar M.; Eisenberg, David S.

    2014-01-01

    New materials capable of binding carbon dioxide are essential for addressing climate change. Here, we demonstrate that amyloids, self-assembling protein fibers, are effective for selective carbon dioxide capture. Solid-state NMR proves that amyloid fibers containing alkylamine groups reversibly bind carbon dioxide via carbamate formation. Thermodynamic and kinetic capture-and-release tests show the carbamate formation rate is fast enough to capture carbon dioxide by dynamic separation, undiminished by the presence of water, in both a natural amyloid and designed amyloids having increased carbon dioxide capacity. Heating to 100 °C regenerates the material. These results demonstrate the potential of amyloid fibers for environmental carbon dioxide capture. PMID:24367077

  5. Evaluation of Equipment Vulnerability and Potential Shock Hazards. [carbon fibers

    NASA Technical Reports Server (NTRS)

    Taback, I.

    1980-01-01

    The vulnerability of electric equipment to carbon fibers released from aircraft accidents is investigated and the parameters affecting vulnerability are discussed. The shock hazard for a hypothetical set of accidents is computed.

  6. A carbon fiber exposure test facility and instrumentation

    NASA Technical Reports Server (NTRS)

    Newcomb, A. L., Jr.

    1980-01-01

    A facility to evaluate the risk associated with the exposure of electrical and electronic equipment to airborne carbon/graphite fibers was constructed. A wide variety of instrumentation is described and illustrated.

  7. The Importance of Carbon Fiber to Polymer Additive Manufacturing

    SciTech Connect

    Love, Lonnie J; Kunc, Vlastimil; Rios, Orlando; Duty, Chad E; Post, Brian K; Blue, Craig A

    2014-01-01

    Additive manufacturing holds tremendous promise in terms of revolutionizing manufacturing. However, fundamental hurdles limit mass adoption of the technology. First, production rates are extremely low. Second, the physical size of parts is generally small, less than a cubic foot. Third, while there is much excitement about metal additive manufacturing, the major growth area is in polymer additive manufacturing systems. Unfortunately, the mechanical properties of the polymer parts are poor, limiting the potential for direct part replacement. To address this issue, we describe three benefits of blending carbon fiber with polymer additive manufacturing. First, development of carbon fiber reinforced polymers for additive manufacturing achieves specific strengths approaching aerospace quality aluminum. Second, carbon fiber radically changes the behavior of the material during deposition, enabling large scale, out-of-the-oven, high deposition rate manufacturing. Finally, carbon fiber technology and additive manufacturing complement each other. Merging the two manufacturing processes enables the construction of complex components that would not be possible otherwise.

  8. Assessment of risk to Boeing commerical transport aircraft from carbon fibers. [fiber release from graphite/epxoy materials

    NASA Technical Reports Server (NTRS)

    Clarke, C. A.; Brown, E. L.

    1980-01-01

    The possible effects of free carbon fibers on aircraft avionic equipment operation, removal costs, and safety were investigated. Possible carbon fiber flow paths, flow rates, and transfer functions into the Boeing 707, 727, 737, 747 aircraft and potentially vulnerable equipment were identified. Probabilities of equipment removal and probabilities of aircraft exposure to carbon fiber were derived.

  9. Transforming Pristine Carbon Fiber Tows into High Performance Solid-State Fiber Supercapacitors.

    PubMed

    Yu, Dingshan; Zhai, Shengli; Jiang, Wenchao; Goh, Kunli; Wei, Li; Chen, Xudong; Jiang, Rongrong; Chen, Yuan

    2015-09-01

    A facile activation strategy can transform pristine carbon fiber tows into high-performance fiber electrodes with a specific capacitance of 14.2 F cm(-3) . The knottable fiber supercapacitor shows an energy density of 0.35 mW h cm(-3) , an ultrahigh power density of 3000 mW cm(-3) , and a remarkable capacitance retention of 68%, when the scan rate increases from 10 to 1000 mV s(-1) . PMID:26179414

  10. Carbon-fiber composite molecular sieves for gas separation

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.; Kimber, G.; Fei, Y.Q.

    1995-08-01

    The progress of research in the development of novel, rigid, monolithic adsorbent carbon fiber composites is described. Carbon fiber composites are produced at ORNL and activated at the CAER using steam or CO{sub 2} under different conditions, with the aims of producing a uniform degree of activation through the material, and of closely controlling pore structure and adsorptive properties The principal focus of the work to date has been to produce materials with narrow porosity for use in gas separations.

  11. Nanowire modified carbon fibers for enhanced electrical energy storage

    NASA Astrophysics Data System (ADS)

    Shuvo, Mohammad Arif Ishtiaque; (Bill) Tseng, Tzu-Liang; Ashiqur Rahaman Khan, Md.; Karim, Hasanul; Morton, Philip; Delfin, Diego; Lin, Yirong

    2013-09-01

    The study of electrochemical super-capacitors has become one of the most attractive topics in both academia and industry as energy storage devices because of their high power density, long life cycles, and high charge/discharge efficiency. Recently, there has been increasing interest in the development of multifunctional structural energy storage devices such as structural super-capacitors for applications in aerospace, automobiles, and portable electronics. These multifunctional structural super-capacitors provide structures combining energy storage and load bearing functionalities, leading to material systems with reduced volume and/or weight. Due to their superior materials properties, carbon fiber composites have been widely used in structural applications for aerospace and automotive industries. Besides, carbon fiber has good electrical conductivity which will provide lower equivalent series resistance; therefore, it can be an excellent candidate for structural energy storage applications. Hence, this paper is focused on performing a pilot study for using nanowire/carbon fiber hybrids as building materials for structural energy storage materials; aiming at enhancing the charge/discharge rate and energy density. This hybrid material combines the high specific surface area of carbon fiber and pseudo-capacitive effect of metal oxide nanowires, which were grown hydrothermally in an aligned fashion on carbon fibers. The aligned nanowire array could provide a higher specific surface area that leads to high electrode-electrolyte contact area thus fast ion diffusion rates. Scanning Electron Microscopy and X-Ray Diffraction measurements are used for the initial characterization of this nanowire/carbon fiber hybrid material system. Electrochemical testing is performed using a potentio-galvanostat. The results show that gold sputtered nanowire carbon fiber hybrid provides 65.9% higher energy density than bare carbon fiber cloth as super-capacitor.

  12. Development of Commodity Grade, Lower Cost Carbon Fiber - Commercial Applications

    SciTech Connect

    Warren, Charles David; Paulauskas, Felix L; Baker, Frederick S; Eberle, Cliff; Naskar, Amit K

    2009-01-01

    In pursuit of the goal to produce ultra-lightweight fuel efficient vehicles, there has been great excitement during the last few years about the potential for using carbon fiber reinforced composites in high volume applications. Currently, the greatest hurdle that inhibits wider implementation of carbon fiber composites in transportation is the high cost of the fiber when compared to other candidate materials. As part of the United States Department of Energy s FreedomCAR initiative, significant research is being conducted to develop lower cost, high volume technologies for producing carbon fiber. This paper will highlight the on-going research in this area. Through Department of Energy (DOE) sponsorship, Oak Ridge National Laboratory (ORNL) and its partners have been working with the US Automotive Composites Consortium (ACC) to develop technologies that would enable the production of carbon fiber at 5-7 dollars per pound. Achievement of this cost goal would allow the introduction of carbon fiber based composites into a greater number of applications for future vehicles. The approach has necessitated the development of both alternative precursors and more efficient production methods. Alternative precursors under investigation include textile grade polyacrylonitrile (PAN) fibers and fibers from lignin-based feedstocks. Previously, as part of the research program, Hexcel Corporation developed the science necessary to allow textile grade PAN to be used as a precursor rather than typical carbon fiber grade precursors. Efforts are also underway to develop carbon fiber precursors from lignin-based feedstocks. ORNL and its partners are working on this effort with domestic pulp and paper producers. In terms of alternative production methods, ORNL has developed a microwave-based carbonization unit that can process pre-oxidized fiber at over 200 inches per minute. ORNL has also developed a new method of high speed oxidation and a new method for precursor stabilization

  13. Carbon fiber enhanced bioelectricity generation in soil microbial fuel cells.

    PubMed

    Li, Xiaojing; Wang, Xin; Zhao, Qian; Wan, Lili; Li, Yongtao; Zhou, Qixing

    2016-11-15

    The soil microbial fuel cell (MFC) is a promising biotechnology for the bioelectricity recovery as well as the remediation of organics contaminated soil. However, the electricity production and the remediation efficiency of soil MFC are seriously limited by the tremendous internal resistance of soil. Conductive carbon fiber was mixed with petroleum hydrocarbons contaminated soil and significantly enhanced the performance of soil MFC. The maximum current density, the maximum power density and the accumulated charge output of MFC mixed carbon fiber (MC) were 10, 22 and 16 times as high as those of closed circuit control due to the carbon fiber productively assisted the anode to collect the electron. The internal resistance of MC reduced by 58%, 83% of which owed to the charge transfer resistance, resulting in a high efficiency of electron transfer from soil to anode. The degradation rates of total petroleum hydrocarbons enhanced by 100% and 329% compared to closed and opened circuit controls without the carbon fiber respectively. The effective range of remediation and the bioelectricity recovery was extended from 6 to 20cm with the same area of air-cathode. The mixed carbon fiber apparently enhanced the bioelectricity generation and the remediation efficiency of soil MFC by means of promoting the electron transfer rate from soil to anode. The use of conductively functional materials (e.g. carbon fiber) is very meaningful for the remediation and bioelectricity recovery in the bioelectrochemical remediation. PMID:27162144

  14. Carbon fiber enhanced bioelectricity generation in soil microbial fuel cells.

    PubMed

    Li, Xiaojing; Wang, Xin; Zhao, Qian; Wan, Lili; Li, Yongtao; Zhou, Qixing

    2016-11-15

    The soil microbial fuel cell (MFC) is a promising biotechnology for the bioelectricity recovery as well as the remediation of organics contaminated soil. However, the electricity production and the remediation efficiency of soil MFC are seriously limited by the tremendous internal resistance of soil. Conductive carbon fiber was mixed with petroleum hydrocarbons contaminated soil and significantly enhanced the performance of soil MFC. The maximum current density, the maximum power density and the accumulated charge output of MFC mixed carbon fiber (MC) were 10, 22 and 16 times as high as those of closed circuit control due to the carbon fiber productively assisted the anode to collect the electron. The internal resistance of MC reduced by 58%, 83% of which owed to the charge transfer resistance, resulting in a high efficiency of electron transfer from soil to anode. The degradation rates of total petroleum hydrocarbons enhanced by 100% and 329% compared to closed and opened circuit controls without the carbon fiber respectively. The effective range of remediation and the bioelectricity recovery was extended from 6 to 20cm with the same area of air-cathode. The mixed carbon fiber apparently enhanced the bioelectricity generation and the remediation efficiency of soil MFC by means of promoting the electron transfer rate from soil to anode. The use of conductively functional materials (e.g. carbon fiber) is very meaningful for the remediation and bioelectricity recovery in the bioelectrochemical remediation.

  15. Tensile Properties of Polyimide Composites Incorporating Carbon Nanotubes-Grafted and Polyimide-Coated Carbon Fibers

    NASA Astrophysics Data System (ADS)

    Naito, Kimiyoshi

    2014-09-01

    The tensile properties and fracture behavior of polyimide composite bundles incorporating carbon nanotubes-grafted (CNT-grafted) and polyimide-coated (PI-coated) high-tensile-strength polyacrylonitrile (PAN)-based (T1000GB), and high-modulus pitch-based (K13D) carbon fibers were investigated. The CNT were grown on the surface of the carbon fibers by chemical vapor deposition. The pyromellitic dianhydride/4,4'-oxydianiline PI nanolayer coating was deposited on the surface of the carbon fiber by high-temperature vapor deposition polymerization. The results clearly demonstrate that CNT grafting and PI coating were effective for improving the Weibull modulus of T1000GB PAN-based and K13D pitch-based carbon fiber bundle composites. In addition, the average tensile strength of the PI-coated T1000GB carbon fiber bundle composites was also higher than that of the as-received carbon fiber bundle composites, while the average tensile strength of the CNT-grafted T1000GB, K13D, and the PI-coated K13D carbon fiber bundle composites was similar to that of the as-received carbon fiber bundle composites.

  16. Carbon Fiber Reinforced Carbon Composite Rotary Valve for an Internal Combustion Engine

    NASA Technical Reports Server (NTRS)

    Northam, G.Burton (Inventor); Ransone, Philip O. (Inventor); Rivers, H. Kevin (Inventor)

    2000-01-01

    Carbon fiber reinforced carbon composite rotary sleeve, and disc valves for internal combustion engines and the like are disclosed. The valves are formed from knitted or braided or wrap-locked carbon fiber shapes. Also disclosed are valves fabricated from woven carbon fibers and from molded carbon matrix material. The valves of the present invention with their very low coefficient of thermal expansion and excellent thermal and self-lubrication properties do not present the sealing and lubrication problems that have prevented rotary sleeve and disc valves from operating efficiently and reliably in the past. Also disclosed are a sealing tang to further improve sealing capabilities and anti-oxidation treatments.

  17. Carbon Fiber Reinforced Carbon Composites Rotary Valves for Internal Combustion Engines

    NASA Technical Reports Server (NTRS)

    Northam, G. Burton (Inventor); Ransone, Philip O. (Inventor); Rivers, H. Kevin (Inventor)

    1999-01-01

    Carbon fiber reinforced carbon composite rotary, sleeve, and disc valves for internal combustion engines and the like are disclosed. The valves are formed from knitted or braided or warp-locked carbon fiber shapes. Also disclosed are valves fabricated from woven carbon fibers and from molded carbon matrix material. The valves of the present invention with their very low coefficient of thermal expansion and excellent thermal and self-lubrication properties, do not present the sealing and lubrication problems that have prevented rotary, sleeve, and disc valves from operating efficiently and reliably in the past. Also disclosed are a sealing tang to further improve sealing capabilities and anti-oxidation treatments.

  18. Improved high modulus carbon fibers. [elimination of hazards due to electrical properties

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Chen, S. H.; Diffendorf, R. J.; Kim, C. M.; Lemaistre, C. W.; Lyman, C. E.; Shen, T. H.; Wang, J. J. H.

    1979-01-01

    Carbon fibers which are electrically insulating but still maintain the mechanical properties of the original carbon fibers were investigated. Three approaches were taken to increase the electrical resistance of carbon fibers: (1) boron nitride (BN) coatings; (2) doping of carbon fibers to alter their electrical properties; and (3) low temperature final heat treatment. The structure of carbon fibers and its effect upon properties was also studied. Results are presented.

  19. Carbon fiber reinforced thermoplastic composites for future automotive applications

    NASA Astrophysics Data System (ADS)

    Friedrich, K.

    2016-05-01

    After a brief introduction to polymer composite properties and markets, the state of the art activities in the field of manufacturing of advanced composites for automotive applications are elucidated. These include (a) long fiber reinforced thermoplastics (LFT) for secondary automotive components, and (b) continuous carbon fiber reinforced thermosetting composites for car body applications. It is followed by future possibilities of carbon fiber reinforced thermoplastic composites for e.g. (i) crash elements, (ii) racing car seats, and (iii) production and recycling of automotive fenders.

  20. Porous texture evolution in Nomex-derived activated carbon fibers.

    PubMed

    Villar-Rodil, S; Denoyel, R; Rouquerol, J; Martínez-Alonso, A; Tascón, J M D

    2002-08-01

    In the present work, the textural evolution of a series of activated carbon fibers with increasing burn-off degree, prepared by the pyrolysis and steam activation of Nomex aramid fibers, is followed by measurements of physical adsorption of N(2) (77 K) and CO(2) (273 K) and immersion calorimetry into different liquids (dichloromethane, benzene, cyclohexane). The immersion calorimetry results are discussed in depth, paying special attention to the choice of the reference material. The activated carbon fibers studied possess an essentially homogeneous microporous texture, which suggests that these materials may be applied in gas separation, either directly or with additional CVD treatment. PMID:16290775

  1. Transverse thermal expansion of carbon fiber/epoxy matrix composites

    NASA Technical Reports Server (NTRS)

    Helmer, J. F.; Diefendorf, R. J.

    1983-01-01

    Thermal expansion coefficients and moduli of elasticity have been determined experimentally for a series of epoxy-matrix composites reinforced with carbon and Kevlar fibers. It is found that in the transverse direction the difference between the properties of the fiber and the matrix is not as pronounced as in the longitudinal direction, where the composite properties are fiber-dominated. Therefore, the pattern of fiber packing tends to affect transverse composite properties. The transverse properties of the composites tested are examined from the standpoint of the concept of homogeneity defined as the variation of packing (or lack thereof) throughout a sample.

  2. Interactions between the glass fiber coating and oxidized carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ku-Herrera, J. J.; Avilés, F.; Nistal, A.; Cauich-Rodríguez, J. V.; Rubio, F.; Rubio, J.; Bartolo-Pérez, P.

    2015-03-01

    Chemically oxidized multiwall carbon nanotubes (MWCNTs) were deposited onto commercial E-glass fibers using a dipping procedure assisted by ultrasonic dispersion. In order to investigate the role of the fiber coating (known as "sizing"), MWCNTs were deposited on the surface of as-received E-glass fibers preserving the proprietary coating as well as onto glass fibers which had the coating deliberately removed. Scanning electron microscopy and Raman spectroscopy were used to assess the distribution of MWCNTs onto the fibers. A rather homogeneous coverage with high density of MWCNTs onto the glass fibers is achieved when the fiber coating is maintained. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR) analyses of the chemical composition of the glass fiber coating suggest that such coating is a complex mixture with multiple oxygen-containing functional groups such as hydroxyl, carbonyl and epoxy. FTIR and XPS of MWCNTs over the glass fibers and of a mixture of MWCNTs and fiber coating provided evidence that the hydroxyl and carboxyl groups of the oxidized MWCNTs react with the oxygen-containing functional groups of the glass fiber coating, forming hydrogen bonding and through epoxy ring opening. Hydrogen bonding and ester formation between the functional groups of the MWCNTs and the silane contained in the coating are also possible.

  3. Mechanical properties of carbon fiber composites for environmental applications

    SciTech Connect

    Andrews, R.; Grulke, E.

    1996-10-01

    Activated carbon fiber composites show great promise as fixed-bed catalytic reactors for use in environmental applications such as flue gas clean-up and ground water decontamination. A novel manufacturing process produces low density composites from chopped carbon fibers and binders. These composites have high permeability, can be activated to have high surface area, and have many potential environmental applications. This paper reports the mechanical and flow properties of these low density composites. Three point flexural strength tests were used to measure composite yield strength and flexural moduli. Composites containing over 10 pph binder had an adequate yield strength of about 200 psi at activations up to 40% weight loss. The composites were anisotropic, having along-fiber to cross-fiber yield strength ratios between 1.2 and 2.0. The friction factor for flow through the composites can be correlated using the fiber Reynolds number, and is affected by the composite bulk density.

  4. Rapid oxidation/stabilization technique for carbon foams, carbon fibers and C/C composites

    DOEpatents

    Tan, Seng; Tan, Cher-Dip

    2004-05-11

    An enhanced method for the post processing, i.e. oxidation or stabilization, of carbon materials including, but not limited to, carbon foams, carbon fibers, dense carbon-carbon composites, carbon/ceramic and carbon/metal composites, which method requires relatively very short and more effective such processing steps. The introduction of an "oxygen spill over catalyst" into the carbon precursor by blending with the carbon starting material or exposure of the carbon precursor to such a material supplies required oxygen at the atomic level and permits oxidation/stabilization of carbon materials in a fraction of the time and with a fraction of the energy normally required to accomplish such carbon processing steps. Carbon based foams, solids, composites and fiber products made utilizing this method are also described.

  5. SURFACE MORPHOLOGY OF CARBON FIBER POLYMER COMPOSITES AFTER LASER STRUCTURING

    SciTech Connect

    Sabau, Adrian S; Chen, Jian; Jones, Jonaaron F.; Alexandra, Hackett; Jellison Jr, Gerald Earle; Daniel, Claus; Warren, Charles David; Rehkopf, Jackie D.

    2015-01-01

    The increasing use of Carbon Fiber Polymer Composite (CFPC) as a lightweight material in automotive and aerospace industries requires the control of surface morphology. In this study, the composites surface was prepared by ablating the resin in the top fiber layer of the composite using an Nd:YAG laser. The CFPC specimens with T700S carbon fiber and Prepreg - T83 resin (epoxy) were supplied by Plasan Carbon Composites, Inc. as 4 ply thick, 0/90o plaques. The effect of laser fluence, scanning speed, and wavelength was investigated to remove resin without an excessive damage of the fibers. In addition, resin ablation due to the power variation created by a laser interference technique is presented. Optical property measurements, optical micrographs, 3D imaging, and high-resolution optical profiler images were used to study the effect of the laser processing on the surface morphology.

  6. Electrospinning of Continuous Carbon Naonofiber-Filled Composite Fibers

    NASA Astrophysics Data System (ADS)

    Aboutalebi, Seyed Hamed; Gholamvand, Zahra; Keyanpour-Rad, Mansoor

    In order to translate the superior properties of carbon nanofibers (CNFs) to macro-scale structures, an electrospinning route capable of placing CNFs into a continuous nano-scale composite fibril is introduced. In this work, composite fibers were produced by electrospinning solution of polyacrylonitrile (PAN) with carbon nanofibers dispersed in dimethylformamide (DMF), which is an effective solvent for carbon nanofibers. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) demonstrated rough and globular surfaces on the CNF containing fibers. Raman spectra confirmed the presence of CNFs in the polymer fibers prepared employing the electrospinning method. Raman observation served as the direct evidence of successful filling of PAN fibers with CNFs and complemented the results obtained by SEM and AFM studies.

  7. Influence of carbon nanotubes coatings onto carbon fiber by oxidative treatments combined with electrophoretic deposition on interfacial properties of carbon fiber composite

    NASA Astrophysics Data System (ADS)

    Deng, Chao; Jiang, Jianjun; Liu, Fa; Fang, Liangchao; Wang, Junbiao; Li, Dejia; Wu, Jianjun

    2015-12-01

    To improve the interfacial performance of carbon fiber (CF) and epoxy resin, carbon nanotubes (CNTs) coatings were utilized to achieve this purpose through coating onto CF by the treatment with hydrogen peroxide and concentrated nitric acid combined with electrophoretic deposition (EPD) process. The influence of electrophoretically deposited CNTs coatings on the surface properties of CFs were investigated by Fourier transform infrared spectrometer, atomic force microscopy, scanning electron microscopy and dynamic contact angle analysis. The results indicated that the deposition of carbon nanotubes introduced some polar groups to carbon fiber surfaces, enhanced surface roughness and changed surface morphologies of carbon fibers. Surface wettability of carbon fibers may be significantly improved by increasing surface free energy of the fibers due to the deposition of CNTs. The thickness and density of the coatings increases with the introduction of pretreatment of the CF during the EPD process. Short beam shear test was performed to examine the effect of carbon fiber functionalization on mechanical properties of the carbon fiber/epoxy resin composites. The interfacial adhesion of CNTs/CF reinforced epoxy composites showed obvious enhancement of interlaminar shear strength by 60.2% and scanning electron microscope photographs showed that the failure mode of composites was changed after the carbon fibers were coated with CNTs.

  8. Carbon nanotube fibers spun from a sizing material

    NASA Astrophysics Data System (ADS)

    Meng, Fancheng; Lu, Weibang; Li, Qingwen; Claes, Michaël; Kchit, Nadir; Chou, Tsu-Wei

    2014-12-01

    Carbon nanotube (CNT) fibers with large pores of hundreds of nanometers in diameter are synthesized from a commercially available sizing material. The pore size can be well controlled by varying the processing conditions including fiber drying temperature and shrinkage ratio. With the use of small amount H2SO4 (1 wt. %), low-concentration (1 wt. %) polyvinyl alcohol (PVA) bath coagulated porous fibers are flexible, with both high mechanical strength and electrical conductivity. Ethylene glycol/methanol mixture bath is also used to fabricate PVA-free porous CNT fibers. The porous fiber demonstrates good performance in foreign components accessing and accommodating, which may facilitate more CNT fiber practical applications, such as absorbents and supercapacitors.

  9. Effect of plasma surface treatment of recycled carbon fiber on carbon fiber-reinforced plastics (CFRP) interfacial properties

    NASA Astrophysics Data System (ADS)

    Lee, Hooseok; Ohsawa, Isamu; Takahashi, Jun

    2015-02-01

    We studied the effects of plasma surface treatment of recycled carbon fiber on adhesion of the fiber to polymers after various treatment times. Conventional surface treatment methods have been attempted for recycled carbon fiber, but most require very long processing times, which may increase cost. Hence, in this study, plasma processing was performed for 0.5 s or less. Surface functionalization was quantified by X-ray photoelectron spectroscopy. O/C increased from approximately 11% to 25%. The micro-droplet test of adhesion properties and the mechanical properties of CFRP were also investigated.

  10. Electromechanical characterization of carbon nanotubes grown on carbon fiber

    NASA Astrophysics Data System (ADS)

    Patton, Steven T.; Zhang, Qiuhong; Qu, Liangti; Dai, Liming; Voevodin, Andrey A.; Baur, Jeff

    2009-11-01

    Mechanical and electrical properties of carbon fiber (CF) and vertically aligned carbon nanotubes (CNTs) have been thoroughly investigated in previous studies. Growth of radially aligned CNTs on silicon oxide (SiO2) coated CF has recently been accomplished resulting in multiscale composite fiber (CNT/SiO2/CF). CNT/SiO2/CF offers promise as stress and strain sensors in CF reinforced composite materials. However, to date there have been no investigations of the electromechanical properties of CNT/SiO2/CF that would facilitate their usage as sensors in composite materials, which is the focus of this research. This study investigates fundamental mechanical and electrical properties of CF, SiO2/CF (SiO2 coated CF), and CNT/SiO2/CF during localized transverse compression at low loads (μN to mN) and small displacements (nm to a few μms). Force, strain, stiffness, and electrical resistance were monitored simultaneously during compression experiments. For CF, resistance decreased sharply upon compressive loading with hysteresis in both force and resistance being observed at low strain. For SiO2/CF, high resistance and negligible electrical conduction occurred, and the force-displacement curve was linear. CNT/SiO2/CF stiffness increased as force and strain increased and became comparable to that of CF at high strain (˜30%). Hysteresis in both force-displacement and resistance-displacement curves was observed with CNT/SiO2/CF, but was more evident as maximum strain increased and did not depend on strain rate. Force was higher and resistance was lower during compression as compared to decompression. Hysteretic energy loss is associated with internal friction between entangled CNTs. Van der Waals force between deformed and entangled CNTs hindered disentanglement, which reduced the number of electrical current paths and increased resistance during decompression. The results of this study provide new understanding of the mechanical and electrical behavior of CNT/SiO2/CF that

  11. Multiscale carbon nanotube-carbon fiber reinforcement for advanced epoxy composites.

    PubMed

    Bekyarova, E; Thostenson, E T; Yu, A; Kim, H; Gao, J; Tang, J; Hahn, H T; Chou, T-W; Itkis, M E; Haddon, R C

    2007-03-27

    We report an approach to the development of advanced structural composites based on engineered multiscale carbon nanotube-carbon fiber reinforcement. Electrophoresis was utilized for the selective deposition of multi- and single-walled carbon nanotubes (CNTs) on woven carbon fabric. The CNT-coated carbon fabric panels were subsequently infiltrated with epoxy resin using vacuum-assisted resin transfer molding (VARTM) to fabricate multiscale hybrid composites in which the nanotubes were completely integrated into the fiber bundles and reinforced the matrix-rich regions. The carbon nanotube/carbon fabric/epoxy composites showed approximately 30% enhancement of the interlaminar shear strength as compared to that of carbon fiber/epoxy composites without carbon nanotubes and demonstrate significantly improved out-of-plane electrical conductivity. PMID:17326671

  12. Effects of fiber, matrix, and interphase on carbon fiber composite compression strength

    NASA Technical Reports Server (NTRS)

    Nairn, John A.; Harper, Sheila I.; Bascom, Willard D.

    1994-01-01

    The major goal of this project was to obtain basic information on compression failure properties of carbon fiber composites. To do this, we investigated fiber effects, matrix effects, and fiber/matrix interface effects. Using each of nine fiber types, we prepared embedded single-fiber specimens, single-ply specimens, and full laminates. From the single-fiber specimens, in addition to the standard fragmentation test analysis, we were able to use the low crack density data to provide information about the distribution of fiber flaws. The single-ply specimens provided evidence of a correlation between the size of kink band zones and the quality of the interface. Results of the laminate compression experiments mostly agreed with the results from single-ply experiments, although the ultimate compression strengths of laminates were higher. Generally, these experiments showed a strong effect of interfacial properties. Matrix effects were examined using laminates subjected to precracking under mixed-mode loading conditions. A large effect of precracking conditions on the mode 1 toughness of the laminates was found. In order to control the properties of the fiber/matrix interface, we prepared composites of carbon fiber and polycarbonate and subjected these to annealing. The changes in interfacial properties directly correlated with changes in compression strength.

  13. Surface and interfacial properties of carbon fibers

    NASA Technical Reports Server (NTRS)

    Bascom, Willard D.

    1991-01-01

    The adhesion strength of AS4 fibers to thermoplastic polymers was determined. The specific polymers were polycarbonate, polyphenylene oxide, polyetherimide, polyphenylene oxide blends with polystyrene, and polycarbonate blends with a polycarbonate-polysiloxan copolymer. Data are also included for polysulfone. It was recognized at the outset that an absolute measure of the fiber matrix adhesion would be difficult. However, it is feasible to determine the fiber bond strengths to the thermoplastics relative to the bond strengths of the same fibers to epoxy polymers. It was anticipated, and in fact realized, that the adhesion of AS4 to the thermoplastic polymers was relatively low. Therefore, further objectives of the study were to identify means of increasing fiber/matrix adhesion and to try to determine why the adhesion of AS4 to thermoplastics is significantly less than to epoxy polymers.

  14. Use of Carbon Fiber Composite Molecular Sieves for Air Separation

    SciTech Connect

    Baker, Frederick S; Contescu, Cristian I; Gallego, Nidia C; Burchell, Timothy D

    2005-09-01

    A novel adsorbent material, 'carbon fiber composite molecular sieve' (CFCMS), has been developed by the Oak Ridge National Laboratory. Its features include high surface area, large pore volume, and a rigid, permeable carbon structure that exhibits significant electrical conductivity. The unique combination of high adsorptive capacity, permeability, good mechanical properties, and electrical conductivity represents an enabling technology for the development of novel gas separation and purification systems. In this context, it is proposed that a fast-cycle air separation process that exploits a kinetic separation of oxygen and nitrogen should be possible using a CFCMS material coupled with electrical swing adsorption (ESA). The adsorption of O{sub 2}, N{sub 2}, and CO{sub 2} on activated carbon fibers was investigated using static and dynamic techniques. Molecular sieving effects in the activated carbon fiber were highlighted by the adsorption of CO{sub 2}, a more sensitive probe molecule for the presence of microporosity in adsorbents. The kinetic studies revealed that O2 was more rapidly adsorbed on the carbon fiber than N{sub 2}, and with higher uptake under equilibrium conditions, providing the fiber contained a high proportion of very narrow micropores. The work indicated that CFCMS is capable of separating O{sub 2} and N{sub 2} from air on the basis of the different diffusion rates of the two molecules in the micropore network of the activated carbon fibers comprising the composite material. In response to recent enquires from several potential users of CFCMS materials, attention has been given to the development of a viable continuous process for the commercial production of CFCMS material. As part of this effort, work was implemented on characterizing the performance of lignin-based activated carbon fiber, a potentially lower cost fiber than the pitch-based fibers used for CFCMS production to date. Similarly, to address engineering issues, measurements were

  15. Energy Absorption in Chopped Carbon Fiber Compression Molded Composites

    SciTech Connect

    Starbuck, J.M.

    2001-07-20

    In passenger vehicles the ability to absorb energy due to impact and be survivable for the occupant is called the ''crashworthiness'' of the structure. To identify and quantify the energy absorbing mechanisms in candidate automotive composite materials, test methodologies were developed for conducting progressive crush tests on composite plate specimens. The test method development and experimental set-up focused on isolating the damage modes associated with the frond formation that occurs in dynamic testing of composite tubes. Quasi-static progressive crush tests were performed on composite plates manufactured from chopped carbon fiber with an epoxy resin system using compression molding techniques. The carbon fiber was Toray T700 and the epoxy resin was YLA RS-35. The effect of various material and test parameters on energy absorption was evaluated by varying the following parameters during testing: fiber volume fraction, fiber length, fiber tow size, specimen width, profile radius, and profile constraint condition. It was demonstrated during testing that the use of a roller constraint directed the crushing process and the load deflection curves were similar to progressive crushing of tubes. Of all the parameters evaluated, the fiber length appeared to be the most critical material parameter, with shorter fibers having a higher specific energy absorption than longer fibers. The combination of material parameters that yielded the highest energy absorbing material was identified.

  16. Characterization of low thermal conductivity PAN-based carbon fibers

    NASA Technical Reports Server (NTRS)

    Katzman, Howard A.; Adams, P. M.; Le, T. D.; Hemminger, Carl S.

    1992-01-01

    The microstructure and surface chemistry of eight low thermal conductivity (LTC) PAN-based carbon fibers were determined and compared with PAN-based fibers heat treated to higher temperatures. Based on wide-angle x ray diffraction, the LTC PAN fibers all appear to have a similar turbostratic structure with large 002 d-spacings, small crystallite sizes, and moderate preferred orientation. Limited small-angle x ray scattering (SAXS) results indicate that, with the exception of LTC fibers made by BASF, the LTC fibers do not have well developed pores. Transmission electron microscopy shows that the texture of the two LTC PAN-based fibers studied (Amoco T350/23X and /25X) consists of multiple sets of parallel, wavy, bent layers that interweave with each other forming a complex three dimensional network oriented randomly around the fiber axis. X ray photoelectron spectroscopy (XPS) analysis finds correlations between heat treated temperatures and the surface composition chemistry of the carbon fiber samples.

  17. The dynamic response of carbon fiber-filled polymer composites

    NASA Astrophysics Data System (ADS)

    Dattelbaum, D. M.; Gustavsen, R. L.; Sheffield, S. A.; Stahl, D. B.; Scharff, R. J.; Rigg, P. A.; Furmanski, J.; Orler, E. B.; Patterson, B.; Coe, J. D.

    2012-08-01

    The dynamic (shock) responses of two carbon fiber-filled polymer composites have been quantified using gas gun-driven plate impact experimentation. The first composite is a filament-wound, highly unidirectional carbon fiber-filled epoxy with a high degree of porosity. The second composite is a chopped carbon fiber- and graphite-filled phenolic resin with little-to-no porosity. Hugoniot data are presented for the carbon fiber-epoxy (CE) composite to 18.6 GPa in the through-thickness direction, in which the shock propagates normal to the fibers. The data are best represented by a linear Rankine-Hugoniot fit: Us = 2.87 + 1.17 ×up(ρ0 = 1.536g/cm3). The shock wave structures were found to be highly heterogeneous, both due to the anisotropic nature of the fiber-epoxy microstructure, and the high degree of void volume. Plate impact experiments were also performed on a carbon fiber-filled phenolic (CP) composite to much higher shock input pressures, exceeding the reactants-to-products transition common to polymers. The CP was found to be stiffer than the filament-wound CE in the unreacted Hugoniot regime, and transformed to products near the shock-driven reaction threshold on the principal Hugoniot previously shown for the phenolic binder itself. [19] On-going research is focused on interrogating the direction-dependent dyanamic response and dynamic failure strength (spall) for the CE composite in the TT and 0∘ (fiber) directions.

  18. Strain measurements on concrete beam and carbon fiber cable with distributed optical fiber Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Nellen, Philipp M.; Bronnimann, Rolf; Sennhauser, Urs J.; Askins, Charles G.; Putnam, Martin A.

    1996-09-01

    We report on civil engineering applications of wavelength multiplexed optical fiber Bragg grating arrays directly produced on the draw tower for testing and surveying advanced structures and materials such as carbon fiber reinforced concrete elements and prestressing cables. We equipped a 6 by 0.9 by 0.5 m concrete beam, which was reinforced with carbon fiber reinforced epoxy laminates, and a 7-m long prestressing carbon fiber cable made of seven twisted strands, with optical fiber Bragg grating sensors. Static strains up to 8000 micrometers/m and dynamic strains up to 1200 micrometers/m were measured with a Michelson interferometer used as Fourier spectrometer with a resolution of about 10 micrometers/m for all sensors. Comparative measurements with electrical resistance strain gauges were in good agreement with the fiber optical results. We installed the fiber sensors in two different arrangements: some Bragg grating array elements measured local strain while others were applied in an extensometric configuration to measure moderate strain over a base length of 0.1 to 1 m.

  19. Polymer/carbon nanotube nano composite fibers--a review.

    PubMed

    Liu, Yaodong; Kumar, Satish

    2014-05-14

    Carbon nanotubes (CNTs) are regarded as ideal filler materials for polymeric fiber reinforcement due to their exceptional mechanical properties and 1D cylindrical geometry (nanometer-size diameter and very high aspect ratio). The reported processing conditions and property improvements of CNT reinforced polymeric fiber are summarized in this review. Because of CNT polymer interaction, polymer chains in CNTs' vicinity (interphase) have been observed to have more compact packing, higher orientation, and better mechanical properties than bulk polymer. Evidences of the existence of interphase polymers in composite fibers, characterizations of their structures, and fiber properties are summarized and discussed. Implications of interphase phenomena on a broader field of fiber and polymer processing to make much stronger materials are now in the early stages of exploration. Beside improvements in tensile properties, the presence of CNTs in polymeric fibers strongly affects other properties, such as thermal stability, thermal transition temperature, fiber thermal shrinkage, chemical resistance, electrical conductivity, and thermal conductivity. This paper will be helpful to better understand the current status of polymer/CNT fibers, especially high-performance fibers, and to find the most suitable processing techniques and conditions. PMID:24520802

  20. Measurement of population inversions and gain in carbon fiber plasmas

    SciTech Connect

    Milchberg, H.; Skinner, C.H.; Suckewer, S.; Voorhees, D.

    1985-10-01

    A CO/sub 2/ laser (approx.0.5 kJ energy, 70 nsec pulse width) was focussed onto the end of an axially oriented, thick (35 to 350 ..mu..) carbon fiber with or without a magnetic field present along the laser-fiber axis. We present evidence for axial-to-transverse enhancement of the CVI 182A (n = 3 ..-->.. 2) transition, which is correlated with the appearance of a population inversion between levels n = 3 and 2. For the B = 0 kG, zero field case, the maximum gain-length product of kl approx. =3 (k approx. =6 cm/sup -1/) was measured for a carbon fiber coated with a thin layer of aluminum (for additional radiation cooling). The results are interpreted in terms of fast recombination due mostly to thermal conduction from the plasma to the cold fiber core.

  1. Carbon fiber composites for cryogenic filament-wound vessels

    NASA Technical Reports Server (NTRS)

    Larsen, J. V.; Simon, R. A.

    1972-01-01

    Advanced unidirectional and bidirectional carbon fiber/epoxy resin composites were evaluated for physical and mechanical properties over a cryogenic to room temperature range for potential application to cryogenic vessels. The results showed that Courtaulds HTS carbon fiber was the superior fiber in terms of cryogenic strength properties in epoxy composites. Of the resin systems tested in ring composites, CTBN/ERLB 4617 exhibited the highest composite strengths at cryogenic temperatures, but very low interlaminar shear strengths at room temperature. Tests of unidirectional and bidirectional composite bars showed that the Epon 828/Empol 1040 resin was better at all test temperatures. Neither fatigue cycling nor thermal shock had a significant effect on composite strengths or moduli. Thermal expansion measurements gave negative values in the fiber direction and positive values in the transverse direction of the composites.

  2. Study and modification of the reactivity of carbon fibers

    NASA Technical Reports Server (NTRS)

    Walker, P. L., Jr.; Ismail, I. M.; Mahajan, O. P.; Eapen, T. A.

    1980-01-01

    The reactivity to air of polyactylonitrile-based carbon fiber cloth was enhanced by the addition of metals to the cloth. The cloth was oxidized in 54 wt% nitric acid in order to increase the surface area of the cloth and to add carbonyl groups to the surface. Metal addition was then achieved by soaking the cloth in metal acetate solution to effect exchange between the metal carbon and hydrogen on the carbonyl groups. The addition of potassium, sodium, calcium and barium enhanced fiber cloth reactivity to air at 573 K. Extended studies using potassium addition showed that success in enhancing fiber cloth reactivity to air depends on: extent of cloth oxidation in nitric acid, time of exchange in potassium acetate solution and the thoroughness of removing metal acetate from the fiber pore structure following exchange. Cloth reactivity increases essentially linearly with increase in potassium addition via exchange.

  3. Mechanical properties of carbon fiber composites for environmental applications

    SciTech Connect

    Andrews, R.; Grulke, E.; Kimber, G.

    1996-12-31

    Activated carbon fiber composites show great promise as fixed-bed catalytic reactors for use in environmental applications such as flue gas clean-up and ground water decontamination. A novel manufacturing process produces low density composites from chopped carbon fibers and binders. These composites have high permeability, can be activated to have high surface area, and have many potential environmental applications. This paper reports the mechanical and flow properties of these low density composites. Three point flexural strength tests were used to measure composite yield strength and flexural moduli. Composites containing over 10 pph binder had an adequate yield strength of about 200 psi at activations up to 40% weight loss. The composites were anisotropic, having along-fiber to cross-fiber yield strength ratios between 1.2 and 2.0. The pressure drop of air through the composites correlated with the gas velocity, and showed a dependence on sample density.

  4. Electronic properties of carbon fibers intercalated with copper chloride

    NASA Technical Reports Server (NTRS)

    Oshima, H.; Natarajan, V.; Woollam, J. A.; Yavrouian, A.; Haugland, E. J.; Tsuzuku, T.

    1984-01-01

    Copper chloride intercalated pitch-based carbon fibers are found to have electrical resistivities as low as 12.9 micro-ohm-cm, and are air- and thermally-stable at and above room temperature. This is therefore a good candidate system for conductor application. In addition, Shubnikov-deHaas quantum oscillatory effects were found, and electronic properties of the intercalated fiber are studied using magnetic fields to 20 tesla.

  5. Apparatus and method for carbon fiber surface treatment

    DOEpatents

    Paulauskas, Felix L.; Sherman, Daniel M.

    2012-07-24

    An apparatus and method for enhancing the surface energy and/or surface chemistry of carbon fibers involves exposing the fibers to direct or indirect contact with atmospheric pressure plasma generated using a background gas containing at least some oxygen or other reactive species. The fiber may be exposed directly to the plasma, provided that the plasma is nonfilamentary, or the fiber may be exposed indirectly through contact with gases exhausting from a plasma discharge maintained in a separate volume. In either case, the process is carried out at or near atmospheric pressure, thereby eliminating the need for vacuum equipment. The process may be further modified by moistening the fibers with selected oxygen-containing liquids before exposure to the plasma.

  6. Apparatus and method for carbon fiber surface treatment

    DOEpatents

    Paulauskas, Felix L; Sherman, Daniel M

    2014-06-03

    An apparatus and method for enhancing the surface energy and/or surface chemistry of carbon fibers involves exposing the fibers to direct or indirect contact with atmospheric pressure plasma generated using a background gas containing at least some oxygen or other reactive species. The fiber may be exposed directly to the plasma, provided that the plasma is nonfilamentary, or the fiber may be exposed indirectly through contact with gases exhausting from a plasma discharge maintained in a separate volume. In either case, the process is carried out at or near atmospheric pressure, thereby eliminating the need for vacuum equipment. The process may be further modified by moistening the fibers with selected oxygen-containing liquids before exposure to the plasma.

  7. A probabilistic analysis of electrical equipment vulnerability to carbon fibers

    NASA Technical Reports Server (NTRS)

    Elber, W.

    1980-01-01

    The statistical problems of airborne carbon fibers falling onto electrical circuits were idealized and analyzed. The probability of making contact between randomly oriented finite length fibers and sets of parallel conductors with various spacings and lengths was developed theoretically. The probability of multiple fibers joining to bridge a single gap between conductors, or forming continuous networks is included. From these theoretical considerations, practical statistical analyses to assess the likelihood of causing electrical malfunctions was produced. The statistics obtained were confirmed by comparison with results of controlled experiments.

  8. Dark pulse generation in fiber lasers incorporating carbon nanotubes.

    PubMed

    Liu, H H; Chow, K K

    2014-12-01

    We demonstrate the generation of dark pulses from carbon nanotube (CNT) incorporated erbium-doped fiber ring lasers with net anomalous dispersion. A side-polished fiber coated with CNT layer by optically-driven deposition method is embedded into the laser in order to enhance the birefringence and nonlinearity of the laser cavity. The dual-wavelength domain-wall dark pulses are obtained from the developed CNT-incorporated fiber laser at a relatively low pump threshold of 50.6 mW. Dark pulses repeated at the fifth-order harmonic of the fundamental cavity frequency are observed by adjusting the intra-cavity polarization state.

  9. Deposition of carbon nanotubes onto aramid fibers using as-received and chemically modified fibers

    NASA Astrophysics Data System (ADS)

    Rodríguez-Uicab, O.; Avilés, F.; Gonzalez-Chi, P. I.; Canché-Escamilla, G.; Duarte-Aranda, S.; Yazdani-Pedram, M.; Toro, P.; Gamboa, F.; Mazo, M. A.; Nistal, A.; Rubio, J.

    2016-11-01

    Multiwall carbon nanotubes (MWCNTs) oxidized by an acid treatment were deposited on the surface of as-received commercial aramid fibers containing a surface coating ("sizing"), and fibers modified by either a chlorosulfonic treatment or a mixture of nitric and sulfuric acids. The surface of the aramid fiber activated by the chemical treatments presents increasing density of CO, COOH and OH functional groups. However, these chemical treatments reduced the tensile mechanical properties of the fibers, especially when the nitric and sulfuric acid mixture was used. Characterization of the MWCNTs deposited on the fiber surface was conducted by scanning electron microscopy, Raman spectroscopy mapping and X-ray photoelectron spectroscopy. These characterizations showed higher areal concentration and more homogeneous distribution of MWCNTs over the aramid fibers for as-received fibers and for those modified with chlorosulfonic acid, suggesting the existence of interaction between the oxidized MWCNTs and the fiber coating. The electrical resistance of the MWCNT-modified aramid yarns comprising ∼1000 individual fibers was in the order of MΩ/cm, which renders multifunctional properties.

  10. Nano-yarn carbon nanotube fiber based enzymatic glucose biosensor

    NASA Astrophysics Data System (ADS)

    Zhu, Zhigang; Song, Wenhui; Burugapalli, Krishna; Moussy, Francis; Li, Ya-Li; Zhong, Xiao-Hua

    2010-04-01

    A novel brush-like electrode based on carbon nanotube (CNT) nano-yarn fiber has been designed for electrochemical biosensor applications and its efficacy as an enzymatic glucose biosensor demonstrated. The CNT nano-yarn fiber was spun directly from a chemical-vapor-deposition (CVD) gas flow reaction using a mixture of ethanol and acetone as the carbon source and an iron nano-catalyst. The fiber, 28 µm in diameter, was made of bundles of double walled CNTs (DWNTs) concentrically compacted into multiple layers forming a nano-porous network structure. Cyclic voltammetry study revealed a superior electrocatalytic activity for CNT fiber compared to the traditional Pt-Ir coil electrode. The electrode end tip of the CNT fiber was freeze-fractured to obtain a unique brush-like nano-structure resembling a scale-down electrical 'flex', where glucose oxidase (GOx) enzyme was immobilized using glutaraldehyde crosslinking in the presence of bovine serum albumin (BSA). An outer epoxy-polyurethane (EPU) layer was used as semi-permeable membrane. The sensor function was tested against a standard reference electrode. The sensitivities, linear detection range and linearity for detecting glucose for the miniature CNT fiber electrode were better than that reported for a Pt-Ir coil electrode. Thermal annealing of the CNT fiber at 250 °C for 30 min prior to fabrication of the sensor resulted in a 7.5 fold increase in glucose sensitivity. The as-spun CNT fiber based glucose biosensor was shown to be stable for up to 70 days. In addition, gold coating of the electrode connecting end of the CNT fiber resulted in extending the glucose detection limit to 25 µM. To conclude, superior efficiency of CNT fiber for glucose biosensing was demonstrated compared to a traditional Pt-Ir sensor.

  11. Nano-yarn carbon nanotube fiber based enzymatic glucose biosensor.

    PubMed

    Zhu, Zhigang; Song, Wenhui; Burugapalli, Krishna; Moussy, Francis; Li, Ya-Li; Zhong, Xiao-Hua

    2010-04-23

    A novel brush-like electrode based on carbon nanotube (CNT) nano-yarn fiber has been designed for electrochemical biosensor applications and its efficacy as an enzymatic glucose biosensor demonstrated. The CNT nano-yarn fiber was spun directly from a chemical-vapor-deposition (CVD) gas flow reaction using a mixture of ethanol and acetone as the carbon source and an iron nano-catalyst. The fiber, 28 microm in diameter, was made of bundles of double walled CNTs (DWNTs) concentrically compacted into multiple layers forming a nano-porous network structure. Cyclic voltammetry study revealed a superior electrocatalytic activity for CNT fiber compared to the traditional Pt-Ir coil electrode. The electrode end tip of the CNT fiber was freeze-fractured to obtain a unique brush-like nano-structure resembling a scale-down electrical 'flex', where glucose oxidase (GOx) enzyme was immobilized using glutaraldehyde crosslinking in the presence of bovine serum albumin (BSA). An outer epoxy-polyurethane (EPU) layer was used as semi-permeable membrane. The sensor function was tested against a standard reference electrode. The sensitivities, linear detection range and linearity for detecting glucose for the miniature CNT fiber electrode were better than that reported for a Pt-Ir coil electrode. Thermal annealing of the CNT fiber at 250 degrees C for 30 min prior to fabrication of the sensor resulted in a 7.5 fold increase in glucose sensitivity. The as-spun CNT fiber based glucose biosensor was shown to be stable for up to 70 days. In addition, gold coating of the electrode connecting end of the CNT fiber resulted in extending the glucose detection limit to 25 microM. To conclude, superior efficiency of CNT fiber for glucose biosensing was demonstrated compared to a traditional Pt-Ir sensor. PMID:20348597

  12. Puncture-Healing Thermoplastic Resin Carbon-Fiber-Reinforced Composites

    NASA Technical Reports Server (NTRS)

    Gordon, Keith L. (Inventor); Siochi, Emilie J. (Inventor); Grimsley, Brian W. (Inventor); Cano, Roberto J. (Inventor); Czabaj, Michael W. (Inventor)

    2015-01-01

    A composite comprising a combination of a self-healing polymer matrix and a carbon fiber reinforcement is described. In one embodiment, the matrix is a polybutadiene graft copolymer matrix, such as polybutadiene graft copolymer comprising poly(butadiene)-graft-poly(methyl acrylate-co-acrylonitrile). A method of fabricating the composite is also described, comprising the steps of manufacturing a pre-impregnated unidirectional carbon fiber preform by wetting a plurality of carbon fibers with a solution, the solution comprising a self-healing polymer and a solvent, and curing the preform. A method of repairing a structure made from the composite of the invention is described. A novel prepreg material used to manufacture the composite of the invention is described.

  13. Carbon fiber composite characterization in adverse thermal environments.

    SciTech Connect

    Gomez-Vasquez, Sylvia; Brown, Alexander L.; Hubbard, Joshua A.; Ramirez, Ciro J.; Dodd, Amanda B.

    2011-05-01

    The behavior of carbon fiber aircraft composites was studied in adverse thermal environments. The effects of resin composition and fiber orientation were measured in two test configurations: 102 by 127 millimeter (mm) test coupons were irradiated at approximately 22.5 kW/m{sup 2} to measure thermal response, and 102 by 254 mm test coupons were irradiated at approximately 30.7 kW/m{sup 2} to characterize piloted flame spread in the vertically upward direction. Carbon-fiber composite materials with epoxy and bismaleimide resins, and uni-directional and woven fiber orientations, were tested. Bismaleimide samples produced less smoke, and were more resistant to flame spread, as expected for high temperature thermoset resins with characteristically lower heat release rates. All materials lost approximately 20-25% of their mass regardless of resin type, fiber orientation, or test configuration. Woven fiber composites displayed localized smoke jetting whereas uni-directional composites developed cracks parallel to the fibers from which smoke and flames emanated. Swelling and delamination were observed with volumetric expansion on the order of 100% to 200%. The purpose of this work was to provide validation data for SNL's foundational thermal and combustion modeling capabilities.

  14. Removal of Ozone by Carbon Nanotubes/Quartz Fiber Film.

    PubMed

    Yang, Shen; Nie, Jingqi; Wei, Fei; Yang, Xudong

    2016-09-01

    Ozone is recognized as a harmful gaseous pollutant, which can lead to severe human health problems. In this study, carbon nanotubes (CNTs) were tested as a new approach for ozone removal. The CNTs/quartz fiber film was fabricated through growth of CNTs upon pure quartz fiber using chemical vapor deposition method. Ozone conversion efficiency of the CNTs/quartz fiber film was tested for 10 h and compared with that of quartz film, activated carbon (AC), and a potassium iodide (KI) solution under the same conditions. The pressure resistance of these materials under different airflow rates was also measured. The results showed that the CNTs/quartz fiber film had better ozone conversion efficiency but also higher pressure resistance than AC and the KI solution of the same weight. The ozone removal performance of the CNTs/quartz fiber film was comparable with AC at 20 times more weight. The CNTs played a dominant role in ozone removal by the CNTs/quartz fiber film. Its high ozone conversion efficiency, lightweight and free-standing properties make the CNTs/quartz fiber film applicable to ozone removal. Further investigation should be focused on reducing pressure resistance and studying the CNT mechanism for removing ozone.

  15. Removal of Ozone by Carbon Nanotubes/Quartz Fiber Film.

    PubMed

    Yang, Shen; Nie, Jingqi; Wei, Fei; Yang, Xudong

    2016-09-01

    Ozone is recognized as a harmful gaseous pollutant, which can lead to severe human health problems. In this study, carbon nanotubes (CNTs) were tested as a new approach for ozone removal. The CNTs/quartz fiber film was fabricated through growth of CNTs upon pure quartz fiber using chemical vapor deposition method. Ozone conversion efficiency of the CNTs/quartz fiber film was tested for 10 h and compared with that of quartz film, activated carbon (AC), and a potassium iodide (KI) solution under the same conditions. The pressure resistance of these materials under different airflow rates was also measured. The results showed that the CNTs/quartz fiber film had better ozone conversion efficiency but also higher pressure resistance than AC and the KI solution of the same weight. The ozone removal performance of the CNTs/quartz fiber film was comparable with AC at 20 times more weight. The CNTs played a dominant role in ozone removal by the CNTs/quartz fiber film. Its high ozone conversion efficiency, lightweight and free-standing properties make the CNTs/quartz fiber film applicable to ozone removal. Further investigation should be focused on reducing pressure resistance and studying the CNT mechanism for removing ozone. PMID:27501513

  16. A comparison of the electrochemical behavior of carbon aerogels and activated carbon fiber cloths

    SciTech Connect

    Tran, T.D.; Alviso, C.T.; Hulsey, S.S.; Nielsen, J.K.; Pekala, R.W.

    1996-05-10

    Electrochemical capacitative behavior of carbon aerogels and commercial carbon fiber cloths was studied in 5M KOH, 3M sulfuric acid, and 0.5M tetrethylammonium tetrafluoroborate/propylene carbonate electrolytes. The resorcinol-formaldehyde based carbon aerogels with a range of denisty (0.2-0.85 g/cc) have open-cell structures with ultrafine pore sizes (5-50 nm), high surface area (400-700 m{sup 2}/g), and a solid matrix composed of interconnected particles or fibers with characteristic diameters of 10 nm. The commercial fiber cloths in the density range 0.2-04g/cc have high surface areas (1000-2500 m{sup 2}/g). The volumetric capacitances of high-density aerogels are shown to be comparable to or exceeding those from activated carbon fibers. Electrochemical behavior of these materials in various electrolytes is compared and related to their physical properties.

  17. Effect of Carbon Nanotubes Upon Emissions From Cutting and Sanding Carbon Fiber-Epoxy Composites

    PubMed Central

    Heitbrink, William A.; Lo, Li-Ming

    2015-01-01

    Carbon nanotubes (CNTs) are being incorporated into structural composites to enhance material strength. During fabrication or repair activities, machining nanocomposites may release CNTs into the workplace air. An experimental study was conducted to evaluate the emissions generated by cutting and sanding on three types of epoxy-composite panels: Panel A containing graphite fibers, Panel B containing graphite fibers and carbon-based mat, and Panel C containing graphite fibers, carbon-based mat, and multi-walled CNTs. Aerosol sampling was conducted with direct-reading instruments, and filter samples were collected for measuring elemental carbon (EC) and fiber concentrations. Our study results showed that cutting Panel C with a band saw did not generate detectable emissions of fibers inspected by transmission electron microscopy but did increase the particle mass, number, and EC emission concentrations by 20% to 80% compared to Panels A and B. Sanding operation performed on two Panel C resulted in fiber emission rates of 1.9×108 and 2.8×106 fibers per second (f/s), while no free aerosol fibers were detected from sanding Panels A and B containing no CNTs. These free CNT fibers may be a health concern. However, the analysis of particle and EC concentrations from these same samples cannot clearly indicate the presence of CNTs, because extraneous aerosol generation from machining the composite epoxy material increased the mass concentrations of the EC. PMID:26478716

  18. Process for preparing tapes from thermoplastic polymers and carbon fibers

    NASA Technical Reports Server (NTRS)

    Chung, Tai-Shung (Inventor); Furst, Howard (Inventor); Gurion, Zev (Inventor); McMahon, Paul E. (Inventor); Orwoll, Richard D. (Inventor); Palangio, Daniel (Inventor)

    1986-01-01

    The instant invention involves a process for use in preparing tapes or rovings, which are formed from a thermoplastic material used to impregnate longitudinally extended bundles of carbon fibers. The process involves the steps of (a) gas spreading a tow of carbon fibers; (b) feeding the spread tow into a crosshead die; (c) impregnating the tow in the die with a thermoplastic polymer; (d) withdrawing the impregnated tow from the die; and (e) gas cooling the impregnated tow with a jet of air. The crosshead die useful in the instant invention includes a horizontally extended, carbon fiber bundle inlet channel, means for providing melted polymer under pressure to the die, means for dividing the polymeric material flowing into the die into an upper flow channel and a lower flow channel disposed above and below the moving carbon fiber bundle, means for applying the thermoplastic material from both the upper and lower channels to the fiber bundle, and means for withdrawing the resulting tape from the die.

  19. Compression Molding of CFRTP Used with Carbon Fiber Extracted from CFRP Waste

    NASA Astrophysics Data System (ADS)

    Kimura, Teruo; Ino, Haruhiro; Nishida, Yuichi; Aoyama, Naoki; Shibata, Katsuji

    This study investigated a compression molding method of carbon fiber reinforced thermoplastics (CFRTP) made of carbon fiber extracted from CFRP waste. The short carbon fibers were mixed with polyester fibers using a papermaking method to make the preform sheet of compression molding. The waste obtained from a textile water jet loom was used as a matrix material. The setting speed of each fiber during the papermaking process was regulated by using a dispersing agent to obtain the good dispersion of each fiber. Laminated preform sheets combined with polyester fibers and carbon fibers were compressed with heating at 300°C and then the polyester fiber was melted as a matrix material. It was cleared from the experimental results that the mechanical properties of molded CFRTP largely depends on both the fiber dispersion and the content of carbon fiber in the preform.

  20. Review and developments of dissemination models for airborne carbon fibers

    NASA Technical Reports Server (NTRS)

    Elber, W.

    1980-01-01

    Dissemination prediction models were reviewed to determine their applicability to a risk assessment for airborne carbon fibers. The review showed that the Gaussian prediction models using partial reflection at the ground agreed very closely with a more elaborate diffusion analysis developed for the study. For distances beyond 10,000 m the Gaussian models predicted a slower fall-off in exposure levels than the diffusion models. This resulting level of conservatism was preferred for the carbon fiber risk assessment. The results also showed that the perfect vertical-mixing models developed herein agreed very closely with the diffusion analysis for all except the most stable atmospheric conditions.

  1. Carbon Fiber Reinforced Ceramic Composites for Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Shivakumar, Kunigal; Argade, Shyam

    2003-01-01

    This report presents a critical review of the processing techniques for fabricating continuous fiber-reinforced CMCs for possible applications at elevated temperatures. Some of the issues affecting durability of the composite materials such as fiber coatings and cracking of the matrix because of shrinkage in PIP-process are also examined. An assessment of the potential inexpensive processes is also provided. Finally three potential routes of manufacturing C/SiC composites using a technology that NC A&T developed for carbon/carbon composites are outlined. Challenges that will be encountered are also listed.

  2. Collector surface for a microwave tube comprising a carbon-bonded carbon-fiber composite

    DOEpatents

    Lauf, Robert J.; McMillan, April D.; Johnson, Arvid C.; Moorhead, Arthur J.

    1998-01-01

    In a microwave tube, an improved collector surface coating comprises a porous carbon composite material, preferably a carbon-bonded carbon fiber composite having a bulk density less than about 2 g/cc. Installation of the coating is readily adaptable as part of the tube manufacturing process.

  3. Collector surface for a microwave tube comprising a carbon-bonded carbon-fiber composite

    DOEpatents

    Lauf, R.J.; McMillan, A.D.; Johnson, A.C.; Moorhead, A.J.

    1998-07-28

    In a microwave tube, an improved collector surface coating comprises a porous carbon composite material, preferably a carbon-bonded carbon fiber composite having a bulk density less than about 2 g/cc. Installation of the coating is readily adaptable as part of the tube manufacturing process. 4 figs.

  4. Adhesion between thermoplastic polymer particles and carbon and glass fibers

    SciTech Connect

    Colton, J.S.

    1996-12-31

    High performance composites consist of polymer matrices reinforced with continuous fibers. Polymer powders can be coated and fused onto the fibers by various techniques to produce these composites. One such technique consists of spreading the fibers with an air banding jet, and then running the fibers through a fluidized bed of the powder. The fluidizing air is typically charged, imparting a charge to the powder particles. The fibers are grounded which leads to an attraction between the particles and the fibers. The particle-coated fibers then go through a tunnel oven, sintering the particles onto the fibers, leaving a flexible {open_quotes}tow-preg{close_quotes} which can then be processed into a preform for manufacture into a final part. To develop an initial understanding of the powder coating process, the adhesion of uncharged particles and fibers was studied. Contact mechanics predicts that the adhesion force between uncharged particles depends on the mutual (or equivalent) radius of curvature between the contacting objects, as well as their surface energies. For the materials of interest, the Derjaguin approximation is appropriate and is applied. PEEK (poly ether ether ketone) and PET (poly ethylene terephthalate) particles, cryogenically ground to nominal diameters of 10 to 100 {mu}m were brought into contact with themselves, with E-glass fibers (nominal diameter of 20 {mu}m), carbon fibers (nominal diameter of 8 {mu}m), and glass microscope slides using an AFM. Adhesion forces were measured and compared to predictions using Derjaguin`s approximation. SEM micrographs were used to determine the scale of the radii of curvature of contacting sites.

  5. Adhesion of novel high-performance polymers to carbon fibers: Fiber surface treatment, characterization, and microbond single fiber pull-out test. Ph.D. Thesis

    SciTech Connect

    Heisey, C.L.

    1993-12-31

    The adhesion of carbon fibers to several high performance polymers, including a phosphorus-containing bismaleimite, a cyanate ester resin, and a pyridine-containing thermoplastic, was evaluated using the microbond single fiber pull-out test. The objective was to determine the chemical and mechanical properties of the fiber and the polymer which affect the fiber/polymer adhesion in a given composite system. Fiber/matrix adhesion is of interest since the degree of adhesion and the nature of the fiber/matrix interphase has a major influence on the mechanical properties of a composite. The surface chemical composition, topography, tensile strength, and surface energy of untreated AU-4 and commercially surface treated AS-4 carbon fibers were evaluated using x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), single fiber tensile tests, and dynamic contact angle analysis. The commercial surface treatment which converted the AU-4 to the AS-4 fiber oxidized the carbon fiber surface. The surface of the AS-4 carbon fiber was further modified using air, oxygen, ammonia, and ethylene plasmas. The AS-4 fiber tow was also characterized following exposure to the aqueous poly(amic acid) solution used to disperse the matrix powder during aqueous suspension prepregging of thermoplastic matrix composites. The air and oxygen plasma treatments significantly oxidized and roughened the surface of the AS-4 carbon fibers. In addition, the air and oxygen plasma increased the polar component of the AS-4 fiber surface energy. The ammonia plasma increased the concentration of nitrogen on the fiber surface, without significantly altering the fiber topography (at a magnification of 50,000X). The atomic oxygen present in the air and oxygen plasma treatments is capable of reacting with both the edge and basal planes in the carbon fiber structure. As a result, the oxygen-containing plasmas progressively ablated the organic material in the carbon fiber surface.

  6. Carbon-fiber composite molecular sieves for gas separation

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.

    1996-08-01

    This report describes continuing work on the activation and characterization of formed carbon fiber composites. The composites are produced at the Oak Ridge National Laboratory (ORNL) and activated at the Center for Applied Energy Research (CAER) using steam, CO{sub 2}, or O{sub 2} at different conditions of temperature and time, and with different furnace configurations. The general aims of the project are to produce uniformly activated samples with controlled pore structures for specialist applications such as gas separation and water treatment. In previous work the authors reported that composites produced from isotropic pitch fibers weighing up to 25g can be uniformly activated through the appropriate choice of reaction conditions and furnace configurations. They have now succeeded in uniformly activating composites of dimensions up to 12 x 7 x 6 cm, or up to about 166 gram - a scale-up factor of about six. Part of the work has involved the installation of a new furnace that can accommodate larger composites. Efforts were made to achieve uniform activation in both steam and CO{sub 2}. The authors have also succeeded in producing materials with very uniform and narrow pore size distributions by using a novel method involving low temperature oxygen chemisorption in combination with heat treatment in N{sub 2} at high temperatures. Work has also started on the activation of PAN based carbon fibers and fiber composites with the aim of producing composites with wide pore structures for use as catalyst supports. So far activation of the PAN fiber composites supplied by ORNL has been difficult which is attributed to the low reactivity of the PAN fibers. As a result, studies are now being made of the activation of the PAN fibers to investigate the optimum carbonization and activation conditions for PAN based fibers.

  7. Carbon nanotubes coated fiber optic ammonia gas sensor

    NASA Astrophysics Data System (ADS)

    Manivannan, S.; Shobin, L. R.; Saranya, A. M.; Renganathan, B.; Sastikumar, D.; Park, Kyu Chang

    2011-01-01

    We report, intrinsic fiber optic carbon nanotubes coated sensor for the detection of ammonia gas at room temperature. Multimode step index polymethyl methacrylate (PMMA) optical fiber passive cladding is partly replaced by an active coating of single and multi-walled carbon nanotubes following the dip coating technique and the reaction with ammonia is studied by measuring the change in output intensity from the optical fiber under various ammonia gas concentrations in the range 0-500 ppm in step of 50 ppm. The sensitivity is calculated for different wavelengths in the range 200-1100 nm both for single and multi-walled carbon nanotubes coated fiber. Higher sensitivities are obtained as 0.26 counts/ppm and 0.31 counts/ppm for single-walled (average diameter 1.3 nm, 30 wt.% purity) and multi-walled (average diameter 10-15 nm, 95 wt.% purity) carbon nanotubes respectively. The role of diameter and purity of carbon nanotubes towards the ammonia sensing is studied and the results are discussed.

  8. The effect of bromination of carbon fibers on the coefficient of thermal expansion of graphite fiber-epoxy composites

    NASA Technical Reports Server (NTRS)

    Jaworske, D. A.; Maciag, C.

    1987-01-01

    To examine the effect of bromination of carbon fibers on the coefficient of thermal expansion (CTE) of carbon fiber epoxy composites, several pristine and brominated carbon fiber-epoxy composite samples were subjected to thermomechanical analysis. The CTE's of these samples were measured in the uniaxial and transverse directions. The CTE was dominated by the fibers in the uniaxial direction, while it was dominated by the matrix in the transverse directions. Bromination had no effect on the CTE of any of the composites. In addition, the CTE of fiber tow was measured in the absence of a polymer matrix, using an extension probe. The results from this technique were inconclusive.

  9. Polyaniline/Carbon Nanotube Composite Fiber-Based Dye-Sensitized Photovoltaic Wire.

    PubMed

    Pan, Shaowu; Yang, Jinhu

    2015-09-01

    Polyaniline/carbon nanotube composite fiber was prepared from aligned multi-walled carbon nano- tube fiber coupling with subsequent electrochemical polymerization of aniline. Novel wire-shaped dye-sensitized solar cells were obtained by using the composite fiber as counter electrode. Photovoltaic wire based on the composite fiber showed a conversion efficiency of 3.8%, which is 63% higher than the pure carbon nanotube fiber. PMID:26716346

  10. Formation of continuous activated carbon fibers for barrier fabrics

    NASA Astrophysics Data System (ADS)

    Liang, Ying

    1997-08-01

    Commercial protective suits made of active carbon granules or nonwoven fabrics are heavy, have low moisture vapor transport rate, and are uncomfortable. Inherent problems due to construction of barrier fabrics lead to severe heat stress when worn for even short time in warm environments. One proposed method to eliminate these problems is to facilitate the construction of a fabric made of continuous activated carbon fibers (CACF). This study is directed toward investigating the possibility of developing CAFC from two precursors: aramid and fibrillated PAN fiber. It was shown in this study that Kevlar-29 fibers could be quickly carbonized and activated to CACF with high adsorptivity and relatively low weight loss. CACF with high surface area (>500 msp2/g) and reasonable tenacity (≈1g/denier) were successfully prepared from Kevlar fibers through a three-step process: pretreatment, carbonization, and activation. X-ray diffraction, Fourier Transform Infrared Spectroscopy (FTIR), and thermal analysis were conducted to understand the evolution of physical and chemical properties during pretreatment. The influence of temperature, heating rate, and pyrolysis environment on the thermal behavior was determined by DSC and TGA/DTA and used as an indicator for optimizing the pyrolysis conditions. Surface analysis by nitrogen isotherms indicated that the resultant fibers had micropores and mesopores on the surface of CACF. This was also inferred by studies on the surface morphology through Scanning Electron Microscopy (SEM) and Scanning Tunneling Microscopy (STM). An investigation of the surface chemical structure by X-ray photoelectron spectroscopy (XPS) before and after activation and elemental analysis confirmed that adsorption of Kevlar based CACF mainly arises due to the physisorption instead of chemisorption. A multistep stabilization along with carbonization and activation was used to prepare active carbon fiber from fibrillated PAN fiber. The resultant fiber retained

  11. Rapid Fabrication of Carbide Matrix/Carbon Fiber Composites

    NASA Technical Reports Server (NTRS)

    Williams, Brian E.; Bernander, Robert E.

    2007-01-01

    Composites of zirconium carbide matrix material reinforced with carbon fibers can be fabricated relatively rapidly in a process that includes a melt infiltration step. Heretofore, these and other ceramic matrix composites have been made in a chemical vapor infiltration (CVI) process that takes months. The finished products of the CVI process are highly porous and cannot withstand temperatures above 3,000 F (approx.1,600 C). In contrast, the melt-infiltration-based process takes only a few days, and the composite products are more nearly fully dense and have withstood temperatures as high as 4,350 F (approx.2,400 C) in a highly oxidizing thrust chamber environment. Moreover, because the melt- infiltration-based process takes much less time, the finished products are expected to cost much less. Fabrication begins with the preparation of a carbon fiber preform that, typically, is of the size and shape of a part to be fabricated. By use of low-temperature ultraviolet-enhanced chemical vapor deposition, the carbon fibers in the preform are coated with one or more interfacial material(s), which could include oxides. The interfacial material helps to protect the fibers against chemical attack during the remainder of the fabrication process and against oxidation during subsequent use; it also enables slippage between the fibers and the matrix material, thereby helping to deflect cracks and distribute loads. Once the fibers have been coated with the interfacial material, the fiber preform is further infiltrated with a controlled amount of additional carbon, which serves as a reactant for the formation of the carbide matrix material. The next step is melt infiltration. The preform is exposed to molten zirconium, which wicks into the preform, drawn by capillary action. The molten metal fills most of the interstices of the preform and reacts with the added carbon to form the zirconium carbide matrix material. The zirconium does not react with the underlying fibers because they

  12. Characterization of carbon fiber reinforced resin composites by the nanoindentation technique

    NASA Astrophysics Data System (ADS)

    Sun, Yuli; Zuo, Dunwen; Cao, Lianjing; Lu, Wenzhuang; Zhu, Yongwei; Li, Jun

    2013-08-01

    The mechanical properties of carbon fiber reinforced resin composites (CFRP) including the epoxy matrix, the carbon fiber and the interface of the carbon fiber/epoxy composites were investigated by means of nanoindentation technique. The hardness, Young's modulus of the components in CFRP were obtained. The results show that the hardness and Young's modulus have a gradient variation from the epoxy matrix to carbon fiber.

  13. Double-peak mechanical properties of carbon-nanotube fibers.

    PubMed

    Zhao, Jingna; Zhang, Xiaohua; Di, Jiangtao; Xu, Geng; Yang, Xiaojie; Liu, Xiangyang; Yong, Zhenzhong; Chen, Minghai; Li, Qingwen

    2010-11-22

    The introduction of twist during the spinning of carbon nanotubes from their arrays (forests) has been widely applied in making ultrastrong, stiff, and lightweight nanotube fibers. Here, for the first time, an important observation of a double-peak behavior of the tensile properties, as a function of the twist angle, that is different from the single peak of traditional fibers is reported. Raman spectra show that the new peak arises from the collapse of nanotubes, showing a strong "nano" element in applying the ancient draw-and-twist technique, besides the downsizing. A qualitative continuum model is also presented to describe the collapse-induced enhancement as well as traditional fibers. Our combined experimental and theoretical studies indicate the direction of full utilization of the nano element in improving the mechanical properties of nanotube fibers. PMID:20941775

  14. Diamagnetic studies on as-processed carbon fibers

    NASA Technical Reports Server (NTRS)

    Scott, C. B.; Fischbach, D. B.

    1976-01-01

    The Faraday method has been used to measure the diamagnetic susceptibilities of small bundles of aligned carbon fibers of different types at room temperature. It was found that the tensor trace susceptibility of the fibers varies systematically over the range 0.8-20 (in units of -10 to the -6th emu/g) as a function of precursor type and processing history. The susceptibility increases, in general, with increasing nominal treatment temperature and hot stretching, and with increasing tensile elastic modulus. The anisotropy ratio of fibers increases approximately linearly with tensile elastic modulus for all fibers from about 1 for a modulus of about 70 GN/sq m to about 22 for a modulus of 700 GN/sq m in air, and is quantitatively consistent with the layer-plane orientation textures determined by X-ray diffraction when appropriate values of the crystallite principal susceptibilities are used.

  15. Treated carbon fibers with improved performance for electrochemical and chemical applications

    DOEpatents

    Chu, Xi; Kinoshita, Kimio

    1999-01-01

    A treated mesophase carbon fiber is disclosed having a high density of exposed edges on the fiber surface, and a method of making such a treated fiber. A carbon electrode is also described which is constructed from such treated mesophase carbon fibers. The resulting electrode, formed from such treated flexible carbon fibers, is characterized by a high density of active sites formed from such exposed edges, low corrosion, and good mechanical strength, and may be fabricated into various shapes. The treated mesophase carbon fibers of the invention are formed by first loading the surface of the mesophase carbon fiber with catalytic metal particles to form catalytic etch sites on a hard carbon shell of the fiber. The carbon fiber is then subject to an etch step wherein portions of the hard carbon shell or skin are selectively removed adjacent the catalytic metal particles adhering to the carbon shell. This exposes the underlying radial edges of the graphite-like layers within the carbon shell of the mesophase carbon fiber, which exposed radial edges then act as active sites of a carbon electrode subsequently formed from the treated mesophase carbon fibers.

  16. Treated carbon fibers with improved performance for electrochemical and chemical applications

    DOEpatents

    Chu, X.; Kinoshita, Kimio

    1999-02-23

    A treated mesophase carbon fiber is disclosed having a high density of exposed edges on the fiber surface, and a method is described for making such a treated fiber. A carbon electrode is also described which is constructed from such treated mesophase carbon fibers. The resulting electrode, formed from such treated flexible carbon fibers, is characterized by a high density of active sites formed from such exposed edges, low corrosion, and good mechanical strength, and may be fabricated into various shapes. The treated mesophase carbon fibers of the invention are formed by first loading the surface of the mesophase carbon fiber with catalytic metal particles to form catalytic etch sites on a hard carbon shell of the fiber. The carbon fiber is then subject to an etch step wherein portions of the hard carbon shell or skin are selectively removed adjacent the catalytic metal particles adhering to the carbon shell. This exposes the underlying radial edges of the graphite-like layers within the carbon shell of the mesophase carbon fiber, which exposed radial edges then act as active sites of a carbon electrode subsequently formed from the treated mesophase carbon fibers. 14 figs.

  17. Amperometric Carbon Fiber Nitrite Microsensor for In Situ Biofilm Monitoring

    EPA Science Inventory

    A highly selective needle type solid state amperometric nitrite microsensor based on direct nitrite oxidation on carbon fiber was developed using a simplified fabrication method. The microsensor’s tip diameter was approximately 7 µm, providing a high spatial resolution of at lea...

  18. Vibration monitoring of carbon fiber composites by multiple fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Olivero, Massimo; Perrone, Guido; Vallan, Alberto; Chen, Wei; Tosi, Daniele

    2014-05-01

    This work presents the comparison between the fiber Bragg grating technology and a vibration-measurement technique based on the detection of polarization rotation (polarimetric sensor) in a standard optical fiber, applied to the dynamic structural monitoring of carbon reinforced composites for the automotive industry. A carbon reinforced composite test plate in a 4-layer configuration was equipped with fiber Bragg gratings and polarimetric fiber sensors, then it was mechanically stressed by static and dynamic loads while monitoring the sensors response. The fiber Bragg grating setup exhibited 1.15+/-0.0016 pm/kg static load response and reproduced dynamic excitation with 0.1% frequency uncertainty, while the polarimetric sensing system exhibited a sensitivity of 1.74+/-0.001 mV/kg and reproduced the dynamic excitation with 0.5% frequency uncertainty. It is shown that the polarimetric sensor technology represents a cheap yet efficient alternative to the fiber Bragg grating sensors in the case of vibration-monitoring of small structures at high frequency.

  19. Approach to the assessment of the hazard. [fire released carbon fiber electrical effects

    NASA Technical Reports Server (NTRS)

    Huston, R. J.

    1980-01-01

    An overview of the carbon fiber hazard assessment is presented. The potential risk to the civil sector associated with the accidental release of carbon fibers from aircraft having composite structures was assessed along with the need for protection of civil aircraft from carbon fibers.

  20. Characterization of porous carbon fibers and related materials

    SciTech Connect

    Fuller, E.L. Jr.

    1996-07-15

    This program was geared to support the Fossil Energy Material Sciences Program with respect to several areas of interest in efficient production and utilization of energy. Carbon molecular sieves have great potential for economically purifying gases; i.e. removal of carbon dioxide from natural gas without having to resort to cryogenic techniques. Microporous carbons can be tailored to serve as adsorbents for natural gas in on-board storage in automotive applications, avoiding high pressures and heavy storage tanks. This program is a laboratory study to evaluate production methodologies and activation processes to produce porous carbons for specific applications. The Carbon Materials Technology Group of Oak Ridge National Laboratory (ORNL) is engaged in developmental programs to produce activated carbon fibers (ACF) for applications in fixed beds and/or flowing reactors engineering applications.

  1. Preparation of array of long carbon nanotubes and fibers therefrom

    DOEpatents

    Arendt, Paul N.; DePaula, Ramond F.; Zhu, Yuntian T.; Usov, Igor O.

    2015-11-19

    An array of carbon nanotubes is prepared by exposing a catalyst structure to a carbon nanotube precursor. Embodiment catalyst structures include one or more trenches, channels, or a combination of trenches and channels. A system for preparing the array includes a heated surface for heating the catalyst structure and a cooling portion that cools gas above the catalyst structure. The system heats the catalyst structure so that the interaction between the precursor and the catalyst structure results in the formation of an array of carbon nanotubes on the catalyst structure, and cools the gas near the catalyst structure and also cools any carbon nanotubes that form on the catalyst structure to prevent or at least minimize the formation of amorphous carbon. Arrays thus formed may be used for spinning fibers of carbon nanotubes.

  2. Laser Processing of Carbon Fiber Reinforced Plastics - Release of Carbon Fiber Segments During Short-pulsed Laser Processing of CFRP

    NASA Astrophysics Data System (ADS)

    Walter, Juergen; Brodesser, Alexander; Hustedt, Michael; Bluemel, Sven; Jaeschke, Peter; Kaierle, Stefan

    Cutting and ablation using short-pulsed laser radiation are promising technologies to produce or repair CFRP components with outstanding mechanical properties e.g. for automotive and aircraft industry. Using sophisticated laser processing strategies and avoiding excessive heating of the workpiece, a high processing quality can be achieved. However, the interaction of laser radiation and composite material causes a notable release of hazardous substances from the process zone, amongst others carbon fiber segments or fibrous particles. In this work, amounts and geometries of the released fiber segments are analyzed and discussed in terms of their hazardous potential. Moreover, it is investigated to what extent gaseous organic process emissions are adsorbed at the fiber segments, similar to an adsorption of volatile organic compounds at activated carbon, which is typically used as filter material.

  3. Evaluation of micron size carbon fibers released from burning graphite composites

    NASA Technical Reports Server (NTRS)

    Sussholz, B.

    1980-01-01

    Quantitative estimates were developed of micron carbon fibers released during the burning of graphite composites. Evidence was found of fibrillated particles which were the predominant source of the micron fiber data obtained from large pool fire tests. The fibrillation phenomena were attributed to fiber oxidation effects caused by the fire environment. Analysis of propane burn test records indicated that wind sources can cause considerable carbon fiber oxidation. Criteria estimates were determined for the number of micron carbon fibers released during an aircraft accident. An extreme case analysis indicated that the upper limit of the micron carbon fiber concentration level was only about half the permissible asbestos ceiling concentration level.

  4. Mechanical properties of continuously spun fibers of carbon nanotubes.

    PubMed

    Motta, Marcelo; Li, Ya-Li; Kinloch, Ian; Windle, Alan

    2005-08-01

    We report on the mechanical properties of fibers consisting of pure carbon nanotube fibers directly spun from an aerogel formed during synthesis by chemical vapor deposition. The continuous withdrawal of product from the gas phase imparts a high commercial potential to the process, either for the production of particularly strong fibers or for the economic production of bulk quantities of carbon nanotubes. Tensile tests were performed on fibers produced from the dissociation of three different hydrocarbons, namely, ethanol, ethylene glycol, and hexane, with a range of iron (catalyst) concentrations. The conditions were chosen to lie within the range known to enable satisfactory continuous spinning, the iron concentration being varied within this range. Increasing proportions of single wall nanotubes were found as the iron concentration was decreased, conditions which also produced fibers of best strength and stiffness. The maximum tensile strength obtained was 1.46 GPa (equivalent to 0.70 N/tex assuming a density of 2.1 g/cm(3)). The experiments indicate that significant improvements in the mechanical properties can be accomplished by optimizing the process conditions. PMID:16089483

  5. Interfacial Microstructure and Enhanced Mechanical Properties of Carbon Fiber Composites Caused by Growing Generation 1-4 Dendritic Poly(amidoamine) on a Fiber Surface.

    PubMed

    Gao, Bo; Zhang, Ruliang; Gao, Fucheng; He, Maoshuai; Wang, Chengguo; Liu, Lei; Zhao, Lifen; Cui, Hongzhi

    2016-08-23

    In an attempt to improve the mechanical properties of carbon fiber composites, propagation of poly(amidoamine) (PAMAM) dendrimers by in situ polymerization on a carbon fiber surface was performed. During polymerization processes, PAMAM was grafted on carbon fiber by repeated Michael addition and amidation reactions. The changes in surface microstructure and the chemical composition of carbon fibers before and after modification were investigated by atomic force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. All the results indicated that PAMAM was successfully grown on the carbon fiber surface. Such propagation could significantly increase the surface roughness and introduce sufficient polar groups onto the carbon fiber surface, enhancing the surface wettability of carbon fiber. The fractured surface of carbon fiber-reinforced composites showed a great enhancement of interfacial adhesion. Compared with those of desized fiber composites, the interlaminar shear strength and interfacial shear strength of PAMAM/fiber-reinforced composites showed increases of 55.49 and 110.94%, respectively.

  6. Carbon fiber plume sampling for large scale fire tests at Dugway Proving Ground. [fiber release during aircraft fires

    NASA Technical Reports Server (NTRS)

    Chovit, A. R.; Lieberman, P.; Freeman, D. E.; Beggs, W. C.; Millavec, W. A.

    1980-01-01

    Carbon fiber sampling instruments were developed: passive collectors made of sticky bridal veil mesh, and active instruments using a light emitting diode (LED) source. These instruments measured the number or number rate of carbon fibers released from carbon/graphite composite material when the material was burned in a 10.7 m (35 ft) dia JP-4 pool fire for approximately 20 minutes. The instruments were placed in an array suspended from a 305 m by 305 m (1000 ft by 1000 ft) Jacob's Ladder net held vertically aloft by balloons and oriented crosswind approximately 140 meters downwind of the pool fire. Three tests were conducted during which released carbon fiber data were acquired. These data were reduced and analyzed to obtain the characteristics of the released fibers including their spatial and size distributions and estimates of the number and total mass of fibers released. The results of the data analyses showed that 2.5 to 3.5 x 10 to the 8th power single carbon fibers were released during the 20 minute burn of 30 to 50 kg mass of initial, unburned carbon fiber material. The mass released as single carbon fibers was estimated to be between 0.1 and 0.2% of the initial, unburned fiber mass.

  7. A phase-stabilized carbon nanotube fiber laser frequency comb.

    PubMed

    Lim, Jinkang; Knabe, Kevin; Tillman, Karl A; Neely, William; Wang, Yishan; Amezcua-Correa, Rodrigo; Couny, François; Light, Philip S; Benabid, Fetah; Knight, Jonathan C; Corwin, Kristan L; Nicholson, Jeffrey W; Washburn, Brian R

    2009-08-01

    A frequency comb generated by a 167 MHz repetition frequency erbium-doped fiber ring laser using a carbon nanotube saturable absorber is phase-stabilized for the first time. Measurements of the in-loop phase noise show an integrated phase error on the carrier envelope offset frequency of 0.35 radians. The carbon nanotube fiber laser comb is compared with a CW laser near 1533 nm stabilized to the nu(1) + nu(3) overtone transition in an acetylene-filled kagome photonic crystal fiber reference, while the CW laser is simultaneously compared to another frequency comb based on a Cr:Forsterite laser. These measurements demonstrate that the stability of a GPS-disciplined Rb clock is transferred to the comb, resulting in an upper limit on the locked comb's frequency instability of 1.2 x 10(-11) in 1 s, and a relative instability of <3 x 10(-12) in 1 s. The carbon nanotube laser frequency comb offers much promise as a robust and inexpensive all-fiber frequency comb with potential for scaling to higher repetition frequencies.

  8. THERMAL INSULATION FROM LIGNIN-DERIVED CARBON FIBERS

    SciTech Connect

    Albers, Tracy; Chen, Chong; Eberle, Cliff; Webb, Daniel C

    2014-01-01

    Oak Ridge National Laboratory (ORNL) and GrafTech International Holdings Inc. (GrafTech) have collaborated to develop and demonstrate the performance of high temperature thermal insulation prototypes made from lignin-based carbon fibers (LBCF). This was the first reported production of LBCF or resulting products at scale > 1 kg. The results will potentially lead to the first commercial application of LBCF. The goal of the commercial application is to replace expensive, foreign-sourced isotropic pitch carbon fibers with lower cost carbon fibers made from a domestically sourced, bio-derived (renewable) feedstock. LBCF can help resolve supply chain vulnerability and reduce the production cost for high temperature thermal insulation as well as create US jobs. The performance of the LBCF prototypes was measured and found to be comparable to that of the current commercial product. During production of the insulation prototypes, the project team demonstrated lignin compounding/pelletization, fiber production, heat treatment, and compositing at scales far surpassing those previously demonstrated in LBCF R&D or production.

  9. Life Cycle Assessment of Carbon Fiber-Reinforced Polymer Composites

    SciTech Connect

    Das, Sujit

    2011-01-01

    Carbon fiber-reinforced polymer matrix composites is gaining momentum with the pressure to lightweight vehicles, however energy-intensity and cost remain some of the major barriers before this material could be used in large-scale automotive applications. A representative automotive part, i.e., a 30.8 kg steel floor pan having a 17% weight reduction potential with stringent cash performance requirements has been considered for the life cycle energy and emissions analysis based on the latest developments occurring in the precursor type (conventional textile-based PAN vs. renewable-based lignin), part manufacturing (conventional SMC vs. P4) and fiber recycling technologies. Carbon fiber production is estimated to be about 14 times more energy-intensive than conventional steel production, however life cycle primary energy use is estimated to be quite similar to the conventional part, i.e., 18,500 MJ/part, especially when considering the uncertainty in LCI data that exists from using numerous sources in the literature. Lignin P4 technology offers the most life cycle energy and CO2 emissions benefits compared to a conventional stamped steel technology. With a 20% reduction in energy use in the lignin conversion to carbon fiber and free availability of lignin as a by-product of ethanol and wood production, a 30% reduction in life cycle energy use could be obtained. A similar level of life cycle energy savings could also be obtained with a higher part weight reduction potential of 43%.

  10. Multifunctional structural supercapacitor composites based on carbon aerogel modified high performance carbon fiber fabric.

    PubMed

    Qian, Hui; Kucernak, Anthony R; Greenhalgh, Emile S; Bismarck, Alexander; Shaffer, Milo S P

    2013-07-10

    A novel multifunctional material has been designed to provide excellent mechanical properties while possessing a high electrochemical surface area suitable for electrochemical energy storage: structural carbon fiber fabrics are embedded in a continuous network of carbon aerogel (CAG) to form a coherent but porous monolith. The CAG-modification process was found to be scalable and to be compatible with a range of carbon fiber fabrics with different surface properties. The incorporation of CAG significantly increased the surface area of carbon fiber fabrics, and hence the electrochemical performance, by around 100-fold, resulting in a CAG-normalized specific electrode capacitance of around 62 F g(-1), determined by cyclic voltammetry in an aqueous electrolyte. Using an ionic liquid (IL) electrolyte, the estimated energy density increased from 0.003 to 1 Wh kg(-1), after introducing the CAG into the carbon fiber fabric. 'Proof-of-concept' multifunctional structural supercapacitor devices were fabricated using an IL-modified solid-state polymer electrolyte as a multifunctional matrix to provide both ionic transport and physical support for the primary fibers. Two CAG-impregnated carbon fabrics were sandwiched around an insulating separator to form a functioning structural electrochemical double layer capacitor composite. The CAG-modification not only improved the electrochemical surface area, but also reinforced the polymer matrix surrounding the primary fibers, leading to dramatic improvements in the matrix-dominated composite properties. Increases in in-plane shear strength and modulus, of up to 4.5-fold, were observed, demonstrating that CAG-modified structural carbon fiber fabrics have promise in both pure structural and multifunctional energy storage applications.

  11. Strong Carbon Nanotube Fibers by Drawing Inspiration from Polymer Fiber Spinning.

    PubMed

    Alemán, Belén; Reguero, Víctor; Mas, Bartolomé; Vilatela, Juan J

    2015-07-28

    We present a method to spin highly oriented continuous fibers of adjustable carbon nanotube (CNT) type, with mechanical properties in the high-performance range. By lowering the concentration of nanotubes in the gas phase, through either reduction of the precursor feed rate or increase in carrier gas flow rate, the density of entanglements is reduced and the CNT aerogel can thus be drawn (up to 18 draw ratio) and wound at fast rates (>50 m/min). This is achieved without affecting the synthesis process, as demonstrated by Raman spectroscopy, and implies that the parameters controlling composition in terms of CNT diameter and number of layers are decoupled from those fixing CNT orientation. Applying polymer fiber wet-spinning principles then, strong CNT fibers (1 GPa/SG) are produced under dilute conditions and high draw ratios, corresponding to highly aligned fibers (from wide- and small-angle X-ray scattering). This is demonstrated for fibers either made up of predominantly single-wall CNTs (SWCNTs) or predominantly multiwall CNTs (MWCNTs), which surprisingly have very similar tensile properties. Finally, we show that postspin densification has no substantial effect on either alignment or properties (mechanical and electrical). These results demonstrate a route to control CNT assembly and reinforce their potential as a high-performance fiber. PMID:26082976

  12. Strong Carbon Nanotube Fibers by Drawing Inspiration from Polymer Fiber Spinning.

    PubMed

    Alemán, Belén; Reguero, Víctor; Mas, Bartolomé; Vilatela, Juan J

    2015-07-28

    We present a method to spin highly oriented continuous fibers of adjustable carbon nanotube (CNT) type, with mechanical properties in the high-performance range. By lowering the concentration of nanotubes in the gas phase, through either reduction of the precursor feed rate or increase in carrier gas flow rate, the density of entanglements is reduced and the CNT aerogel can thus be drawn (up to 18 draw ratio) and wound at fast rates (>50 m/min). This is achieved without affecting the synthesis process, as demonstrated by Raman spectroscopy, and implies that the parameters controlling composition in terms of CNT diameter and number of layers are decoupled from those fixing CNT orientation. Applying polymer fiber wet-spinning principles then, strong CNT fibers (1 GPa/SG) are produced under dilute conditions and high draw ratios, corresponding to highly aligned fibers (from wide- and small-angle X-ray scattering). This is demonstrated for fibers either made up of predominantly single-wall CNTs (SWCNTs) or predominantly multiwall CNTs (MWCNTs), which surprisingly have very similar tensile properties. Finally, we show that postspin densification has no substantial effect on either alignment or properties (mechanical and electrical). These results demonstrate a route to control CNT assembly and reinforce their potential as a high-performance fiber.

  13. High performance carbon fibers from very high molecular weight polyacrylonitrile precursors

    DOE PAGES

    Morris, E. Ashley; Weisenberger, Matthew C.; Abdallah, Mohamed G.; Vautard, Frederic; Grappe, Hippolyte A.; Ozcan, Soydan; Paulauskas, Felix L.; Eberle, Cliff; Jackson, David C.; Mecham, Sue J.; et al

    2016-02-02

    In this study, carbon fibers are unique reinforcing agents for lightweight composite materials due to their outstanding mechanical properties and low density. Current technologies are capable of producing carbon fibers with 90-95% of the modulus of perfect graphite (~1025 GPa). However, these same carbon fibers possess less than 10% of the theoretical carbon fiber strength, estimated to be about 100 GPa.[1] Indeed, attempts to increase carbon fiber rigidity results in lower breaking strength. To develop advanced carbon fibers with both very high strength and modulus demands a new manufacturing methodology. Here, we report a method of manufacturing high strength, verymore » high modulus carbon fibers from a very high molecular weight (VHMW) polyacrylonitrile (PAN) precursor without the use of nanomaterial additives such as nucleating or structure-templating agents, as have been used by others.[2,3]« less

  14. Influence of Lignin modification on PAN-Lignin copolymers as potential carbon fiber precursors

    NASA Astrophysics Data System (ADS)

    Ramasubramanian, Gauri

    Carbon fiber based polymer composites have been recognized as advanced materials for structural applications. The unique reinforcing abilities of carbon fibers with their combination of high strength-to-weight ratio and excellent fatigue resistance have made carbon fiber based composites exceptional compared to other fiber reinforced composites. However, the high cost involved in current precursor materials for carbon fibers has limited the widespread applicability of carbon fibers. Hence, intensification of research efforts towards cheaper and easily available raw material for fabrication of carbon fibers is justified. The growing demand for low cost carbon fibers for mainstream composite applications has driven recent interests in using lignin as alternative choice of material for carbon fiber precursor. Lignin is a highly aromatic, plant-derived amorphous polymer and has been considered as potential low-cost, bio-based carbon fiber precursor. Copolymers of polyacrylonitrile/lignin were developed as alternative precursors for fabrication of raw fibers using conventional solution spinning techniques. Lignin/polyacrylonitrile copolymers were successfully synthesized and characterized using FT-IR and NMR techniques. The thermal properties of the copolymers were studied by DSC and TGA analysis. The effect of chemical modification on the morphology and stability of the carbon fibers from PAN-Lignin copolymers has been studied using Raman Spectroscopy, X-ray Diffraction and Scanning Electron Microscopy. Modification of lignin prior to copolymerization provided a significant advantage in the improvement of precursor processability using solution spinning. Additionally, carbon fibers obtained from copolymers containing different varieties of lignins were examined. Carbon fibers produced from organosolv lignin/polyacrylonitrile copolymers exhibit promising carbon fiber structure when compared to softwood/lignin polyacrylonitrile copolymers.

  15. Modified carbon fibers to improve composite properties. [sizing fibers for reduced electrical conductivity and adhesion during combustion

    NASA Technical Reports Server (NTRS)

    Shepler, R. E.

    1979-01-01

    Thin coatings, 5 to 10 wt. percent, were applied to PAN-based carbon fibers. These coatings were intended to make the carbon fibers less electrically conductive or to cause fibers to stick together when a carbon fiber/epoxy composite burned. The effectiveness of the coatings in these regards was evaluated in burn tests with a test rig designed to simulate burning, impact and wind conditions which might release carbon fibers. The effect of the coatings on fiber and composite properties and handling was also investigated. Attempts at sizing carbon fibers with silicon dioxide, silicon carbide and boron nitride meet with varying degrees of success; however, none of these materials provided an electrically nonconductive coating. Coatings intended to stick carbon fibers together after a composite burned were sodium silicate, silica gel, ethyl silicate, boric acid and ammonium borate. Of these, only the sodium silicate and silica gel provided any sticking together of fibers. The amount of sticking was insufficient to achieve the desired objectives.

  16. A New Fiber Preform with Nanocarbon Binder for Manufacturing Carbon Fiber Reinforced Composite by Liquid Molding Process.

    PubMed

    Seong, Dong Gi; Ha, Jong Rok; Lee, Jea Uk; Lee, Wonoh; Kim, Byung Sun

    2015-11-01

    Carbon fiber reinforced composite has been a good candidate of lightweight structural component in the automotive industry. As fast production speed is essential to apply the composite materials for the mass production area such as automotive components, the high speed liquid composite molding processes have been developed. Fast resin injection through the fiber preform by high pressure is required to improve the production speed, but it often results in undesirable deformations of the fiber preform which causes defectives in size and properties of the final composite products. In order to prevent the undesirable deformation and improve the stability of preform shape, polymer type binder materials are used. More stable fiber preform can be obtained by increasing the amount of binder material, but it disturbs the resin impregnation through the fiber preform. In this study, carbon nanomaterials such as graphene oxide were embedded on the surface of carbon fiber by electrophoretic deposition method in order to improve the shape stability of fiber preform and interfacial bonding between polymer and the reinforcing fiber. Effects of the modified reinforcing fiber were investigated in two respects. One is to increase the binding energy between fiber tows, and the other is to increase the interfacial bonding between polymer matrix and fiber surface. The effects were analyzed by measuring the binding force of fiber preform and interlaminar shear strength of the composite. This study also investigated the high speed liquid molding process of the composite materials composed of polymer matrix and the carbon fiber preforms embedded by carbon nanomaterials. Process parameter such as permeability of fiber preform was measured to investigate the effect of nanoscale surface modification on the macroscale processing condition for composite manufacturing. PMID:26726642

  17. A New Fiber Preform with Nanocarbon Binder for Manufacturing Carbon Fiber Reinforced Composite by Liquid Molding Process.

    PubMed

    Seong, Dong Gi; Ha, Jong Rok; Lee, Jea Uk; Lee, Wonoh; Kim, Byung Sun

    2015-11-01

    Carbon fiber reinforced composite has been a good candidate of lightweight structural component in the automotive industry. As fast production speed is essential to apply the composite materials for the mass production area such as automotive components, the high speed liquid composite molding processes have been developed. Fast resin injection through the fiber preform by high pressure is required to improve the production speed, but it often results in undesirable deformations of the fiber preform which causes defectives in size and properties of the final composite products. In order to prevent the undesirable deformation and improve the stability of preform shape, polymer type binder materials are used. More stable fiber preform can be obtained by increasing the amount of binder material, but it disturbs the resin impregnation through the fiber preform. In this study, carbon nanomaterials such as graphene oxide were embedded on the surface of carbon fiber by electrophoretic deposition method in order to improve the shape stability of fiber preform and interfacial bonding between polymer and the reinforcing fiber. Effects of the modified reinforcing fiber were investigated in two respects. One is to increase the binding energy between fiber tows, and the other is to increase the interfacial bonding between polymer matrix and fiber surface. The effects were analyzed by measuring the binding force of fiber preform and interlaminar shear strength of the composite. This study also investigated the high speed liquid molding process of the composite materials composed of polymer matrix and the carbon fiber preforms embedded by carbon nanomaterials. Process parameter such as permeability of fiber preform was measured to investigate the effect of nanoscale surface modification on the macroscale processing condition for composite manufacturing.

  18. System to continuously produce carbon fiber via microwave assisted plasma processing

    DOEpatents

    White, Terry L [Knoxville, TN; Paulauskas, Felix L [Knoxville, TN; Bigelow, Timothy S [Knoxville, TN

    2010-11-02

    A system to continuously produce fully carbonized or graphitized carbon fibers using microwave-assisted plasma (MAP) processing comprises an elongated chamber in which a microwave plasma is excited in a selected gas atmosphere. Fiber is drawn continuously through the chamber, entering and exiting through openings designed to minimize in-leakage of air. There is a gradient of microwave power within the chamber with generally higher power near where the fiber exits and lower power near where the fiber enters. Polyacrylonitrile (PAN), pitch, or any other suitable organic/polymeric precursor fibers can be used as a feedstock for the inventive system. Oxidized or partially oxidized PAN or pitch or other polymeric fiber precursors are run continuously through a MAP reactor in an inert, non-oxidizing atmosphere to heat the fibers, drive off the unwanted elements such as oxygen, nitrogen, and hydrogen, and produce carbon or graphite fibers faster than conventionally produced carbon fibers.

  19. BASIC PROPERTIES OF REFERENCE CROSSPLY CARBON-FIBER COMPOSITE

    SciTech Connect

    Corum, J.M.

    2001-01-11

    This report provides basic in-air property data and correlations-tensile, compressive, shear, tensile fatigue, and tensile creep-for a reference carbon-fiber composite being characterized as a part of the Durability of Carbon-Fiber Composites Project at Oak Ridge National Laboratory. The overall goal of the project, which is sponsored by the Department of Energy's Office of Advanced Automotive Materials and is closely coordinated with the Advanced Composites Consortium, is to develop durability-based design guidance for polymeric composites for automotive structural applications. The composite addressed here is a {+-}45{degree} crossply consisting of continuous Thornel T300 fibers in a Baydur 420 IMR urethane matrix. Basic tensile, compressive, and shear properties are tabulated for the temperature range from {minus}40 to 120 C. Fatigue response at room-temperature and 120 C are presented, and creep and creep rupture at room temperature only are reported. In all cases, two fiber orientations--0/90{degree} and {+-}45{degree}--relative to the specimen axes are addressed. The properties and correlations presented are interim in nature. They are intended as a baseline for planning a full durability test program on this reference composite.

  20. Vapor grown carbon fiber for space thermal management systems

    NASA Technical Reports Server (NTRS)

    Lake, Max L.; Hickok, J. Kyle; Brito, Karren K.; Begg, Lester L.

    1990-01-01

    Research that uses a novel, highly graphitic, vapor grown carbon fiber (VGCF) to fabricate composites for thermal management applications is described. These VGCF/Carbon composites have shown a specific thermal conductivity with values of twenty-to-ten times that of copper in the 500-900 K temperature range needed for waste heat management. It is concluded that development of this high specific thermal conductivity composite for thermal radiator panels will provide the foundation for a reevaluation of space power designs heretofore limited by the mass of waste heat dissipation systems. Further, it is suggested that through optimization of fiber handling and composite processing, thermal conductivities exceeding 1000 W/m-K (at 300 K) are achievable in composites reinforced with VGCF.

  1. Activation and micropore structure of carbon-fiber composites

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.; Kimber, G.

    1997-12-01

    Rigid, high surface area activated carbon fiber composites have been produced with high permeabilities for environmental applications in gas and water purification. The project involves a collaboration between the Oak Ridge National Laboratory (ORNL) and the Center for Applied Energy Research (CAER), University of Kentucky. The main focus of recent work has been to find a satisfactory means to uniformly activate large samples of carbon fiber composites to produce controlled pore structures. Processes have been developed using activation in steam and CO{sub 2}, and a less conventional method involving oxygen chemisorption and subsequent heat treatment. Another objective has been to explore applications for the activated composites in environmental applications related to fossil energy production.

  2. Defect visualization in carbon fiber composite using laser ultrasound

    SciTech Connect

    Dewhurst, R.J.; He, Ruhua; Shan, Qing . Dept. of Instrumentation and Analytical Science)

    1993-08-01

    A non-contacting laser ultrasound system has been developed to visualize laminar defects in carbon fiber composite materials. Laser-generated ultrasound (LGU) was produced from a Nd:YAG Q-switched laser. Ultrasound was detected with the use of an actively stabilized Fabry-Perot interferometer using a 400 mW argon-ion laser source. It detected ultrasound in a typical frequency range of 1 to 10 MHz. Through-transmission C-scan measurements were made in carbon fiber composite materials of thickness 1 to 20 mm. Peak-to-peak amplitudes of the first longitudinal ultrasonic pulse were measured, with attenuation used as the basis of defect examination. Digital filtering was adopted to enhance defect visibility. Results showed that images with size resolution better than 1 mm can be achieved. Such measurements take into account any variation of surface reflectivity which can arise in industrial materials.

  3. Dry synthesis of lithium intercalated graphite powders and carbon fibers

    SciTech Connect

    Sacci, Robert L; Adamczyk, Leslie A; Veith, Gabriel M; Dudney, Nancy J

    2014-01-01

    Herein we describe the direct synthesis of lithium intercalated graphite by heating under vacuum or ball milling under pressurized Ar(g). Both methods allow for stoichometric control of Li-C ratio in batter-grade graphites and carbon fibers prior formation of a solid electrolyte interphase. The products' surface chemistries, as probed by XPS, suggest that LiC6 are extremely reactive with trace amounts of moisture or oxygen. The open circuit potential and SEM data show that the reactivity of the lithiated battery-grade graphite and the carbon fiber can be related to the density of edge/defect sites on the surfaces. Preliminary results of spontaneous SEI formation on Li-graphite in electrolyte are also given.

  4. Effect of surface modification on carbon fiber and its reinforced phenolic matrix composite

    NASA Astrophysics Data System (ADS)

    Yuan, Hua; Wang, Chengguo; Zhang, Shan; Lin, Xue

    2012-10-01

    In this work, polyacrylonitrile (PAN)-based carbon fiber were chemically modified with H2SO4, KClO3 and silane coupling agent (γ-aminopropyltriethoxysilane, APS), and carbon fiber reinforced phenolic matrix composites were prepared. The structural and surface characteristics of the carbon fiber were investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), laser Raman scattering (LRS) and Fourier transform infrared spectroscopy (FTIR). Single fiber mechanical properties, specific surface area, composite impact properties and interfacial shear strength (ILSS) were researched to indicate the effects of surface modification on fibers and the interaction between modified fiber surface and phenolic matrix. The results showed that carbon fiber surface modification by oxidation and APS can strengthen fiber surface chemical activity and enlarge the fiber surface area as well as its roughness. When carbon fiber (CF) is oxidized treatment, the oxygen content as well as the O/C ratio will be obviously increased. Oxygen functional groups increase with oxidation time increasing. Carbon fiber treated with APS will make Csbnd Osbnd R content increase and Osbnd Cdbnd O content decrease due to surface reaction. Proper treatment of carbon fiber with acid and silane coupling agent prove an effective way to increase the interfacial adhesion and improve the mechanical and outdoor performance of the resulting fiber/resin composites.

  5. Production of graphene oxide from pitch-based carbon fiber

    NASA Astrophysics Data System (ADS)

    Lee, Miyeon; Lee, Jihoon; Park, Sung Young; Min, Byunggak; Kim, Bongsoo; in, Insik

    2015-07-01

    Pitch-based graphene oxide (p-GO) whose compositional/structural features are comparable to those of graphene oxide (GO) was firstly produced by chemical exfoliation of pitch-based carbon fiber rather than natural graphite. Incorporation of p-GO as nanofillers into poly(methyl methacrylate) (PMMA) as a matrix polymer resulted in excellent mechanical reinforcement. p-GO/PMMA nanocomposite (1 wt.-% p-GO) demonstrated 800% higher modulus of toughness of neat PMMA.

  6. Carbon-Fiber/Epoxy Tube Lined With Aluminum Foil

    NASA Technical Reports Server (NTRS)

    Gernet, Nelson J.; Kerr, Gregory K.

    1995-01-01

    Carbon-fiber/epoxy composite tube lined with welded aluminum foil useful as part of lightweight heat pipe in which working fluid ammonia. Aluminum liner provides impermeability for vacuum seal, to contain ammonia in heat pipe, and to prevent flow of noncondensable gases into heat pipe. Similar composite-material tubes lined with foils also incorporated into radiators, single- and two-phase thermal buses, tanks for storage of cryogenic materials, and other plumbing required to be lightweight.

  7. Production of graphene oxide from pitch-based carbon fiber

    PubMed Central

    Lee, Miyeon; Lee, Jihoon; Park, Sung Young; Min, Byunggak; Kim, Bongsoo; In, Insik

    2015-01-01

    Pitch-based graphene oxide (p-GO) whose compositional/structural features are comparable to those of graphene oxide (GO) was firstly produced by chemical exfoliation of pitch-based carbon fiber rather than natural graphite. Incorporation of p-GO as nanofillers into poly(methyl methacrylate) (PMMA) as a matrix polymer resulted in excellent mechanical reinforcement. p-GO/PMMA nanocomposite (1 wt.-% p-GO) demonstrated 800% higher modulus of toughness of neat PMMA. PMID:26156067

  8. Carbon fiber composite molecular sieve electrically regenerable air filter media

    DOEpatents

    Wilson, Kirk A.; Burchell, Timothy D.; Judkins, Roddie R.

    1998-01-01

    An electrically regenerable gas filter system includes a carbon fiber composite molecular sieve (CFCMS) filter medium. After a separate medium-efficiency pre-filter removes particulate from the supply airstream, the CFCMS filter sorbs gaseous air pollutants before the air is recirculated to the space. When saturated, the CFCMS media is regenerated utilizing a low-voltage current that is caused to pass through the filter medium.

  9. Carbon fiber composite molecular sieve electrically regenerable air filter media

    DOEpatents

    Wilson, K.A.; Burchell, T.D.; Judkins, R.R.

    1998-10-27

    An electrically regenerable gas filter system includes a carbon fiber composite molecular sieve (CFCMS) filter medium. After a separate medium-efficiency pre-filter removes particulate from the supply air stream, the CFCMS filter sorbs gaseous air pollutants before the air is recirculated to the space. When saturated, the CFCMS media is regenerated utilizing a low-voltage current that is caused to pass through the filter medium. 3 figs.

  10. Pitch-based short carbon fiber. Final report

    SciTech Connect

    Lin, S.S.

    1991-12-01

    Short carbon fiber manufactured from coal tar pitch by Osaka Gas Co. is examined by chemical composition analysis, X-ray powder diffraction, optical microscope, and electron spectroscopic techniques. The present analytical results are compared with the data obtainable from other sources. Owing to the low cost of the short fiber, it is recommended that the fiber could be used for a wide variety of reinforcement applications such as, cement/concrete mixtures, polymer composites, and high temperature materials. Processing includes the mechanical separation of mesophase microbeads of three to 30 micron diameters from crude coal tar during three heat treatment stages. The mesophases obtained are then subjected to solvent extraction, hydrogenation, and polymerization to yield isotropic and anisotropic pitches suitable for melt spinning. The short fiber is fabricated from isotropic pitch by the rotary gas jet method, and the process yields a higher quality fiber as compared to other melt spinning methods. The most important feature is that this process is highly cost effective.

  11. Carbon nanotube fibers are compatible with Mammalian cells and neurons.

    PubMed

    Dubin, R A; Callegari, G; Kohn, J; Neimark, A

    2008-03-01

    We demonstrate the biocompatibility of carbon nanotube fibers (CNFs) fabricated from single-wall carbon nanotubes. Produced by a particle-coagulation spinning process, CNFs are "hair-like" conductive microwires, which uniquely combine properties of porous nanostructured scaffolds, high-area electrodes, and permeable microfluidic conduits. We report that CNFs are nontoxic and support the attachment, spreading, and growth of mammalian cells and the extension of processes from neurons in vitro. Our findings suggest that CNF may be employed for an electrical interfacing of nerve cells and external devices. PMID:18334451

  12. Development of multifunctional carbon fiber reinforced composites (CFRCs) - Manufacturing process

    NASA Astrophysics Data System (ADS)

    Guadagno, Liberata; Raimondo, Marialuigia; Vietri, Umberto; Barra, Giuseppina; Vertuccio, Luigi; Volponi, Ruggero; Cosentino, Giovanni; De Nicola, Felice; Grilli, Andrea; Spena, Paola

    2014-05-01

    This work describes a successful attempt toward the development of CFRCs based on nanofilled epoxy resins. The epoxy matrix was prepared by mixing a tetrafunctional epoxy precursor with a reactive diluent which allows to reduce the viscosity of the initial epoxy precursor and facilitate the nanofiller dispersion step. As nanofiller, multiwall carbon nanotubes (MWCNTs) were embedded in the epoxy matrix with the aim of improving the electrical properties of the resin used to manufacture CFRCs. Panels were manufactured by Resin Film Infusion (RFI) using a non-usual technique to infuse a nano-filled resin into a carbon fiber dry preform.

  13. Microstructure and properties of SiC-coated carbon fibers prepared by radio frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Cheng, Yong; Huang, Xiaozhong; Du, Zuojuan; Xiao, Jianrong; Zhou, Shan; Wei, Yongshan

    2016-04-01

    SiC-coated carbon fibers are prepared at room temperature with different radio-frequency magnetron sputtering powers. Results show that the coated carbon fibers have uniform, continuous, and flawless surfaces. The mean strengths of the coated carbon fibers with different sputtering powers are not influenced by other factors. Filament strength of SiC-coated carbon fibers increases by approximately 2% compared with that of uncoated carbon fibers at a sputtering power of <200 W. The filament strengths of the coated fibers increase by 9.3% and 12% at sputtering powers of 250 and 300 W, respectively. However, the mean strength of the SiC-coated carbon fibers decreased by 8% at a sputtering power of 400 W.

  14. Ultrasonic Fatigue Endurance of Thin Carbon Fiber Sheets

    NASA Astrophysics Data System (ADS)

    Domínguez Almaraz, Gonzalo M.; Ruiz Vilchez, Julio A.; Dominguez, Aymeric; Meyer, Yann

    2016-04-01

    Ultrasonic fatigue tests were carried out on thin carbon fiber sheets (0.3 mm of thickness) to determine the fatigue endurance under very high-frequency loading (20 kHz). This material, called the gas diffusion layer (GDL), plays a major role in the overall performances of proton exchange membrane fuel cells (PEMFCs). The study of its physical-chemical properties is an on-going subject in the literature; nevertheless, no knowledge is available concerning the high-frequency fatigue endurance. A principal difficulty in carrying out ultrasonic fatigue tests on this material was to determine the dimensions of testing specimen to fit the resonance condition. This aspect was solved by modal numerical simulation: The testing specimen has been a combination of a low-strength steel frame (to facilitate the attachment to the ultrasonic machine and to increase the mass of the specimen), and the carbon fiber hourglass-shape profile. Under resonance condition, a stationary elastic wave is generated along the specimen that induces high stress at the neck section and high displacements at the ends. Results show that fatigue life was close to 3 × 108 cycles when the high Von Misses stress at the neck section was 170 MPa, whereas fatigue life attains the 4.5 × 109 cycles when stress decreases to 117 MPa. Crack initiation and propagation were analyzed, and conclusions were drawn concerning the fatigue endurance of these fiber carbon sheets under ultrasonic fatigue testing.

  15. MNASA as a Test for Carbon Fiber Thermal Barrier Development

    NASA Technical Reports Server (NTRS)

    Bauer, Paul; McCool, Alex (Technical Monitor)

    2001-01-01

    A carbon fiber rope thermal barrier is being evaluated as a replacement for the conventional room temperature vulcanizing (RTV) thermal barrier that is currently used to protect o-rings in Reusable Solid Rocket Motor (RSRM) nozzle joints. Performance requirements include its ability to cool any incoming, hot propellant gases that fill and pressurize the nozzle joints, filter slag and particulates, and to perform adequately in various joint assembly conditions as well as dynamic flight motion. Modified National Aeronautics and Space Administration (MNASA) motors, with their inherent and unique ability to replicate select RSRM internal environment features, were an integral step in the development path leading to full scale RSRM static test demonstration of the carbon fiber rope (CFR) joint concept. These 1/4 scale RSRM motors serve to bridge the gap between the other classes of subscale test motors (extremely small and moderate duration, or small scale and short duration) and the critical asset RSRM static test motors. A series of MNASA tests have been used to demonstrate carbon fiber rope performance and have provided rationale for implementation into a full-scale static motor and flight qualification.

  16. Radiation-curable carbon fiber prepreg composites

    SciTech Connect

    Saunders, C.B.; Dickson, L.W.; Singh, A.; Carmichael, A.A.; Lopata, V.J.

    1988-12-01

    A radiation-curable prepreg designed to meet the specifications set by a major aircraft company is described. The resin, consisting of a mixture of an epoxy diacrylate, polybutadiene diacrylate, and a multifunctional monomer, was used to impregnate a plain weave carbon fabric by a solvent process. The cured polymer, produced by irradiation in air to a dose of 40 kGy, is amorphous, with a gel fraction of 85 percent. The linear thermal expansion coefficient of the polymer was found to be 0.00017 m/m deg C from 25 to 150 C; it was not affected by varying the applied irradiation dose from 30 to 50 kGy. 14 references.

  17. Tensile Properties and Fracture Behavior of Different Carbon Nanotube-Grafted Polyacrylonitrile-Based Carbon Fibers

    NASA Astrophysics Data System (ADS)

    Naito, Kimiyoshi

    2014-11-01

    The tensile properties and fracture behavior of different carbon nanotube (CNT)-grafted polyacrylonitrile-based (T1000GB) single carbon fibers were investigated. Grafting of CNTs was achieved via chemical vapor deposition (CVD). When Fe(C5H5)2 (also applied via CVD) was used as the catalyst, the tensile strength and Weibull modulus of the carbon fibers were improved, possibly due to the growth of dense CNT networks on the carbon fibers, which may have led to a reduction in the number of strength-limiting defects. Separately, at lower concentrations of an Fe(NO3)3·9H2O catalyst in ethanol, which was applied via dipping, the tensile strength of CNT-grafted fibers was nearly identical to that of the as-received fibers, although the Weibull modulus was higher. For higher concentrations of the Fe(NO3)3·9H2O catalyst, however, the tensile strength and the Weibull modulus were lower than those for the as-received material. Although the density of the CNT network increased with the concentration of the Fe(NO3)3·9H2O catalyst in the ethanol solution, heating of the ethanolic Fe(NO3)3·9H2O catalyst solution generated nitric acid (HNO3) due to decomposition, which damaged the fiber surfaces, resulting in an increase in the number of flaws and consequently a reduction in the tensile strength. Therefore, the tensile strength and Weibull modulus of CNT-grafted carbon fibers vary due to the combination of these effects and as a function of the catalyst concentration.

  18. Studies of the Surface Treatment and Sizing of Carbon Fiber Surfaces on the Mechanical Properties of Composites Containing Carbon Fibers

    NASA Technical Reports Server (NTRS)

    Sherwood, Peter M. A.; Lease, Kevin B.; Locke, James E.; Tomblin, John S.; Wang, Youqi

    1996-01-01

    Carbon fiber reinforced composites are materials where carbon fibers are used to reinforce a matrix to produce a light and strong material with important applications in the aerospace industry. There are many aspects of the preparation of these materials that would benefit from a study which combines the research of groups involved in the production, testing and analysis of these materials, and studies of the basic surface chemistry involved. This final reports presents the results of a project that has developed a collaboration between groups in all three of the major research universities in the State of Kansas, and promises to lead to a collaborative program that covers the major aspects of composite development and application. Sherwood has provided initial fiber surface treatment and sizing together with fiber and composite surface analysis; Lease, Tomblin and Wang have worked together toward the goal of preparing pre-preg and fabrication of laminated panels; Locke has developed computational models to evaluate the effect of surface treatment (and chemistry) on mechanical properties; Lease, Tomblin and Wang have worked together to perform all necessary mechanical testing. The research has been focused on materials that would benefit the High Speed Civil Transport (HSCT) program. The group has visited Dr. Howard Maars and his colleagues at NASA Langley, and has focused their studies on the NASA requirements discussed in this meeting. An important development, requested by NASA scientists, has been the acquisition and study of K3B as a matrix material for the composites. The project has led to the successful acquisition and surface analysis of K3B, together with the successful deposition of this material onto surface oxidized carbon fibers. Mechanical testing, modelling and the construction of composite preparation equipment has been achieved during the grant period.

  19. Method of making carbon fiber-carbon matrix reinforced ceramic composites

    NASA Technical Reports Server (NTRS)

    Williams, Brian (Inventor); Benander, Robert (Inventor)

    2007-01-01

    A method of making a carbon fiber-carbon matrix reinforced ceramic composite wherein the result is a carbon fiber-carbon matrix reinforcement is embedded within a ceramic matrix. The ceramic matrix does not penetrate into the carbon fiber-carbon matrix reinforcement to any significant degree. The carbide matrix is a formed in situ solid carbide of at least one metal having a melting point above about 1850 degrees centigrade. At least when the composite is intended to operate between approximately 1500 and 2000 degrees centigrade for extended periods of time the solid carbide with the embedded reinforcement is formed first by reaction infiltration. Molten silicon is then diffused into the carbide. The molten silicon diffuses preferentially into the carbide matrix but not to any significant degree into the carbon-carbon reinforcement. Where the composite is intended to operate between approximately 2000 and 2700 degrees centigrade for extended periods of time such diffusion of molten silicon into the carbide is optional and generally preferred, but not essential.

  20. Effects of precursor thermal aging and fiber arrangement on the properties of carbon/carbon (C/C) composites

    SciTech Connect

    Ma, C.C.M.; Chang, W.C.; Tai, N.H.

    1993-12-31

    Carbon/carbon composites fabricated by the pyrolysis of high strength carbon fiber fabrics reinforced phenolic resin were investigated. A liquid impregnation process has been used to fabricate composite precursor for 2-D carbon/carbon composite and an unique pultrusion process also used to fabricate the 1-D carbon/carbon composite precursor. Effects of thermal aging of the precursor on flexural strength of the resulted carbon/carbon composites are studied. Results shows that suitable thermal aging improves the flexural properties of carbon/carbon composites in this study. And based on the SEM examination and flexural tests, they show that the 2-D plain woven fiber arrangement results the significant degradation of the carbon fiber and the decreasing of composites flexural properties.

  1. Artificial muscles of dielectric elastomers attached to artificial tendons of functionalized carbon fibers

    NASA Astrophysics Data System (ADS)

    Ye, Zhihang; Faisal, Md. Shahnewaz Sabit; Asmatulu, Ramazan; Chen, Zheng

    2014-03-01

    Dielectric elastomers are soft actuation materials with promising applications in robotics and biomedical de- vices. In this paper, a bio-inspired artificial muscle actuator with artificial tendons is developed for robotic arm applications. The actuator uses dielectric elastomer as artificial muscle and functionalized carbon fibers as artificial tendons. A VHB 4910 tape is used as the dielectric elastomer and PDMS is used as the bonding material to mechanically connect the carbon fibers to the elastomer. Carbon fibers are highly popular for their high electrical conductivities, mechanical strengths, and bio-compatibilities. After the acid treatments for the functionalization of carbon fibers (500 nm - 10 μm), one end of carbon fibers is spread into the PDMS material, which provides enough bonding strength with other dielectric elastomers, while the other end is connected to a DC power supply. To characterize the actuation capability of the dielectric elastomer and electrical conductivity of carbon fibers, a diaphragm actuator is fabricated, where the carbon fibers are connected to the actuator. To test the mechanical bonding between PDMS and carbon fibers, specimens of PDMS bonded with carbon fibers are fabricated. Experiments have been conducted to verify the actuation capability of the dielectric elastomer and mechanical bonding of PDMS with carbon fibers. The energy efficiency of the dielectric elastomer increases as the load increases, which can reach above 50%. The mechanical bonding is strong enough for robotic arm applications.

  2. Model for the Effect of Fiber Bridging on the Fracture Resistance of Reinforced-Carbon-Carbon

    NASA Technical Reports Server (NTRS)

    Chan, Kwai S.; Lee, Yi-Der; Hudak, Stephen J., Jr.

    2009-01-01

    A micromechanical methodology has been developed for analyzing fiber bridging and resistance-curve behavior in reinforced-carbon-carbon (RCC) panels with a three-dimensional (3D) composite architecture and a silicon carbide (SiC) surface coating. The methodology involves treating fiber bridging traction on the crack surfaces in terms of a weight function approach and a bridging law that relates the bridging stress to the crack opening displacement. A procedure has been developed to deduce material constants in the bridging law from the linear portion of the K-resistance curve. This report contains information on the application of procedures and outcomes.

  3. Photoelectrochemical cell using dye sensitized zinc oxide nanowires grown on carbon fibers

    NASA Astrophysics Data System (ADS)

    Unalan, Husnu Emrah; Wei, Di; Suzuki, Kenichi; Dalal, Sharvari; Hiralal, Pritesh; Matsumoto, Hidetoshi; Imaizumi, Shinji; Minagawa, Mie; Tanioka, Akihiko; Flewitt, Andrew J.; Milne, William I.; Amaratunga, Gehan A. J.

    2008-09-01

    Zinc oxide (ZnO) nanowires (NWs) grown on carbon fibers using a vapor transport and condensation approach are used as the cathode of a photoelectrochemical cell. The carbon fibers were obtained by electrospray deposition and take the form of a flexible carbon fabric. The ZnO NW on carbon fiber anode is combined with a "black dye" photoabsorber, an electrolyte, and a platinum (Pt) counterelectrode to complete the cell. The results show that ZnO NW and carbon fibers can be used for photoinduced charge separation/charge transport and current collection, respectively, in a photoelectrochemical cell.

  4. Process Optimization of Bismaleimide (BMI) Resin Infused Carbon Fiber Composite

    NASA Technical Reports Server (NTRS)

    Ehrlich, Joshua W.; Tate, LaNetra C.; Cox, Sarah B.; Taylor, Brian J.; Wright, M. Clara; Faughnan, Patrick D.; Batterson, Lawrence M.; Caraccio, Anne J.; Sampson, Jeffery W.

    2013-01-01

    Engineers today are presented with the opportunity to design and build the next generation of space vehicles out of the lightest, strongest, and most durable materials available. Composites offer excellent structural characteristics and outstanding reliability in many forms that will be utilized in future aerospace applications including the Commercial Crew and Cargo Program and the Orion space capsule. NASA's Composites for Exploration (CoEx) project researches the various methods of manufacturing composite materials of different fiber characteristics while using proven infusion methods of different resin compositions. Development and testing on these different material combinations will provide engineers the opportunity to produce optimal material compounds for multidisciplinary applications. Through the CoEx project, engineers pursue the opportunity to research and develop repair patch procedures for damaged spacecraft. Working in conjunction with Raptor Resins Inc., NASA engineers are utilizing high flow liquid infusion molding practices to manufacture high-temperature composite parts comprised of intermediate modulus 7 (IM7) carbon fiber material. IM7 is a continuous, high-tensile strength composite with outstanding structural qualities such as high shear strength, tensile strength and modulus as well as excellent corrosion, creep, and fatigue resistance. IM7 carbon fiber, combined with existing thermoset and thermoplastic resin systems, can provide improvements in material strength reinforcement and deformation-resistant properties for high-temperature applications. Void analysis of the different layups of the IM7 material discovered the largest total void composition within the [ +45 , 90 , 90 , -45 ] composite panel. Tensile and compressional testing proved the highest mechanical strength was found in the [0 4] layup. This paper further investigates the infusion procedure of a low-cost/high-performance BMI resin into an IM7 carbon fiber material and the

  5. Magnetic alignment of nickel-coated carbon fibers

    SciTech Connect

    Hao, Chuncheng; Li, Xiaojiao; Wang, Guizhen

    2011-11-15

    Graphical abstract: Carbon nanofibers were subjected to a two-step pretreatment, sensitization and activation. Carbon nanofibers were encapsulated by a uniform layer of nickel nanoparticles. The prepared composites are ferromagnetic and with a small value of coercivity. Upon such functionalization, the carbon nanofibers can be aligned in a relatively small external magnetic field. Highlights: {center_dot} A simple microwave-assisted procedure for the magnetic composite. {center_dot} Dense layer of nickel on pretreated carbon nanofibers. {center_dot} Ferromagnetic properties and low coercivity. {center_dot} A long-chain aligned structure under magnetic field. -- Abstract: Magnetic composites of nickel-coated carbon nanofibers have been successfully fabricated by employing a simple microwave-assisted procedure. The scanning electron microscopy images show that a complete and uniform nickel coating with mean size of 25 nm could be deposited on carbon fibers. Magnetization curves demonstrate that the prepared composites are ferromagnetic and that the coercivity is 96 Oe. The magnetic carbon nanofibers can be aligned as a long-chain structure in an external magnetic field.

  6. Multiscale Analysis of Delamination of Carbon Fiber-Epoxy Laminates with Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Riddick, Jaret C.; Frankland, SJV; Gates, TS

    2006-01-01

    A multi-scale analysis is presented to parametrically describe the Mode I delamination of a carbon fiber/epoxy laminate. In the midplane of the laminate, carbon nanotubes are included for the purposes of selectively enhancing the fracture toughness of the laminate. To analyze carbon fiber epoxy carbon nanotube laminate, the multi-scale methodology presented here links a series of parameterizations taken at various length scales ranging from the atomistic through the micromechanical to the structural level. At the atomistic scale molecular dynamics simulations are performed in conjunction with an equivalent continuum approach to develop constitutive properties for representative volume elements of the molecular structure of components of the laminate. The molecular-level constitutive results are then used in the Mori-Tanaka micromechanics to develop bulk properties for the epoxy-carbon nanotube matrix system. In order to demonstrate a possible application of this multi-scale methodology, a double cantilever beam specimen is modeled. An existing analysis is employed which uses discrete springs to model the fiber bridging affect during delamination propagation. In the absence of empirical data or a damage mechanics model describing the effect of CNTs on fracture toughness, several tractions laws are postulated, linking CNT volume fraction to fiber bridging in a DCB specimen. Results from this demonstration are presented in terms of DCB specimen load-displacement responses.

  7. Enhanced performance of electrospun carbon fibers modified with carbon nanotubes: promising electrodes for enzymatic biofuel cells

    NASA Astrophysics Data System (ADS)

    Both Engel, A.; Cherifi, A.; Tingry, S.; Cornu, D.; Peigney, A.; Laurent, Ch

    2013-06-01

    New nanostructured electrodes, promising for the production of clean and renewable energy in biofuel cells, were developed with success. For this purpose, carbon nanofibers were produced by the electrospinning of polyacrylonitrile solution followed by convenient thermal treatments (stabilization followed by carbonization at 1000, 1200 and 1400° C), and carbon nanotubes were adsorbed on the surfaces of the fibers by a dipping method. The morphology of the developed electrodes was characterized by several techniques (SEM, Raman spectroscopy, electrical conductivity measurement). The electrochemical properties were evaluated through cyclic voltammetry, where the influence of the carbonization temperature of the fibers and the beneficial contribution of the carbon nanotubes were observed through the reversibility and size of the redox peaks of K3Fe(CN)6 versus Ag/AgCl. Subsequently, redox enzymes were immobilized on the electrodes and the electroreduction of oxygen to water was realized as a test of their efficiency as biocathodes. Due to the fibrous and porous structure of these new electrodes, and to the fact that carbon nanotubes may have the ability to promote electron transfer reactions of redox biomolecules, the new electrodes developed were capable of producing higher current densities than an electrode composed only of electrospun carbon fibers.

  8. Enhanced performance of electrospun carbon fibers modified with carbon nanotubes: promising electrodes for enzymatic biofuel cells.

    PubMed

    Engel, A Both; Cherifi, A; Tingry, S; Cornu, D; Peigney, A; Laurent, Ch

    2013-06-21

    New nanostructured electrodes, promising for the production of clean and renewable energy in biofuel cells, were developed with success. For this purpose, carbon nanofibers were produced by the electrospinning of polyacrylonitrile solution followed by convenient thermal treatments (stabilization followed by carbonization at 1000, 1200 and 1400° C), and carbon nanotubes were adsorbed on the surfaces of the fibers by a dipping method. The morphology of the developed electrodes was characterized by several techniques (SEM, Raman spectroscopy, electrical conductivity measurement). The electrochemical properties were evaluated through cyclic voltammetry, where the influence of the carbonization temperature of the fibers and the beneficial contribution of the carbon nanotubes were observed through the reversibility and size of the redox peaks of K3Fe(CN)6 versus Ag/AgCl. Subsequently, redox enzymes were immobilized on the electrodes and the electroreduction of oxygen to water was realized as a test of their efficiency as biocathodes. Due to the fibrous and porous structure of these new electrodes, and to the fact that carbon nanotubes may have the ability to promote electron transfer reactions of redox biomolecules, the new electrodes developed were capable of producing higher current densities than an electrode composed only of electrospun carbon fibers.

  9. Thermal conductivity, electrical conductivity and specific heat of copper-carbon fiber composite

    NASA Technical Reports Server (NTRS)

    Kuniya, Keiichi; Arakawa, Hideo; Kanai, Tsuneyuki; Chiba, Akio

    1988-01-01

    A new material of copper/carbon fiber composite is developed which retains the properties of copper, i.e., its excellent electrical and thermal conductivity, and the property of carbon, i.e., a small thermal expansion coefficient. These properties of the composite are adjustable within a certain range by changing the volume and/or the orientation of the carbon fibers. The effects of carbon fiber volume and arrangement changes on the thermal and electrical conductivity, and specific heat of the composite are studied. Results obtained are as follows: the thermal and electrical conductivity of the composite decrease as the volume of the carbon fiber increases, and were influenced by the fiber orientation. The results are predictable from a careful application of the rule of mixtures for composites. The specific heat of the composite was dependent, not on fiber orientation, but on fiber volume. In the thermal fatigue tests, no degradation in the electrical conductivity of this composite was observed.

  10. Adhesion of preceramic inorganic polymer coatings to carbon fibers

    SciTech Connect

    Chaudhry, T.M.; Drzal, L.T.; Ho, H.; Laine, R.

    1996-12-31

    To determine whether the preceramic inorganic polymer coating can provide not only the thermal oxidative protection during both processing and use in metal matrix composites or ceramic matrix composites but also the appropriate composite properties, it is desirable to know how and at what point in the thermal processing cycle the coating-carbon fiber interface undergoes changes that affect the interfacial adhesion and failure mode. Also, it is important to identify the locus of interfacial failure i.e. between fiber and coating or between coating and matrix. This work is directed at determining the interfacial changes and the locus of failure in order to optimize both the coating chemistry and the conversion process. The characteristics of the benchmark interface coating material, silicon oxycarbide, SiO{sub x}C{sub y} or black glass have been studied. SiO{sub x}C{sub y} was chosen because (1) SiO{sub x}C{sub y} is amorphous, (2) it is possible to prepare very well-defined materials, where the chemistry and the evolution of the material with time and temperature are known in detail, and (3) SiO{sub x}C{sub y} is a matrix material used in commercial composites. It has been shown that these coatings are effective in increasing the oxidation resistance of the carbon fibers themselves.

  11. Carbon fiber study. A compilation of an intergovernmental committee study

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Carbon fibers have opened a wealth of new structural engineering and consumer product opportunities. The potential benefits are higher strength, and lighter weight military and commercial products, which portend energy savings and increases safety. Unfortunately, these benefits are not realized without risk. Inadvertent fiber release, during manufacture or by destruction of the resin binder in fire, is the major hazard associated with composites. The carbon (or graphite) fibers are finer than human hair and if released into the air, they can be easily transported by winds or currents. In contact with electrical devices, they can create resistive loading, short circuits, and arcing, resulting in stoppages or destruction. Their health impact is not fully known and requires careful research and analysis before any firm conclusions can be reached; however, based upon current available information, they are primarily an irritant to the eyes and skin, like fiberglass, rather than carcinogenic or destructive to lung tissue. Major manufacturers are aware of the unique problems associated with these materials and have successfully applied controls to avoid the inplant problems.

  12. Bonded carbon or ceramic fiber composite filter vent for radioactive waste

    DOEpatents

    Brassell, Gilbert W.; Brugger, Ronald P.

    1985-02-19

    Carbon bonded carbon fiber composites as well as ceramic or carbon bonded ceramic fiber composites are very useful as filters which can separate particulate matter from gas streams entraining the same. These filters have particular application to the filtering of radioactive particles, e.g., they can act as vents for containers of radioactive waste material.

  13. Nanocomposite fibers and film containing polyolefin and surface-modified carbon nanotubes

    DOEpatents

    Chu,Benjamin; Hsiao, Benjamin S.

    2010-01-26

    Methods for modifying carbon nanotubes with organic compounds are disclosed. The modified carbon nanotubes have enhanced compatibility with polyolefins. Nanocomposites of the organo-modified carbon nanotubes and polyolefins can be used to produce both fibers and films having enhanced mechanical and electrical properties, especially the elongation-to-break ratio and the toughness of the fibers and/or films.

  14. Characterization of Porous Carbon Fibers and Related Materials

    SciTech Connect

    Fuller, E.L., Jr.

    1993-01-01

    A one-year subcontract sponsored by the Carbon Materials Technology Group of the Oak Ridge National Laboratory (ORNL) with the Department of Geological Sciences, University Of Tennessee, has been completed. A volumetric sorption system has been upgraded, in cooperation with commercial vendor, to allow the acquisition of data relevant to the program for the production of activated carbon molecular fiber sieves (ACFMS). The equipment and experimental techniques have been developed to determine the pore structure and porosity of reference materials and materials produced at ORNL as part of the development of methods for the activation of carbon fibers by various etching agents. Commercial activated coconut shell charcoal (ACSC) has been studied to verify instrument performance and to develop methodology for deducing cause and effects in the activation processes and to better understand the industrial processes (gas separation, natural gas storage, etc.). Operating personnel have been trained, standard operating procedures have been established, and quality assurance procedures have been developed and put in place. Carbon dioxide and methane sorption have been measured over a temperature range 0 to 200 C for both ACFMS and ACSC and similarities and differences related to the respective structures and mechanisms of interaction with the sorbed components. Nitrogen sorption (at 77 K) has been used to evaluate ''surface area'' and ''porosity'' for comparison with the large data base that exists for other activated carbons and related materials. The preliminary data base reveals that techniques and theories currently used to evaluate activated carbons may be somewhat erroneous and misleading. Alternate thermochemical and structural analyses have been developed that show promise in providing useful information related both to the activation process and to industrial applications of interest in the efficient and economical utilization of fossil fuels in a manner that is

  15. A small-scale test for fiber release from carbon composites. [pyrolysis and impact

    NASA Technical Reports Server (NTRS)

    Gilwee, W. J., Jr.; Fish, R. H.

    1980-01-01

    A test method was developed to determine relative fiber loss from pyrolyzed composites with different resins and fiber construction. Eleven composites consisting of woven and unwoven carbon fiber reinforcement and different resins were subjected to the burn and impact test device. The composites made with undirectional tape had higher fiber loss than those with woven fabric. Also, the fiber loss was inversely proportional to the char yield of the resin.

  16. A series of tufted carbon fiber cathodes designed for different high power microwave sources

    NASA Astrophysics Data System (ADS)

    Liu, Lie; Li, Limin; Zhang, Jun; Zhang, Xiaoping; Wen, Jianchun; Liu, Yonggui

    2008-06-01

    We report the fabrication technique of tufted carbon fiber cathodes for different microwave sources. Three carbon fiber cathodes were constructed, including a planar cathode, an annular cathode, and a cylindrical cathode for radial emission. Experimental investigations on these cathodes were performed in a reflex triode virtual cathode oscillator (vircator), a backward wave oscillator (BWO), and a magnetically insulated transmission line oscillator (MILO), respectively. The pulse duration of microwave emission from the reflex triode vircator was lengthened by using the planar carbon fiber cathode. In the BWO with the annular carbon fiber cathode, the uniform electron beam with a kA /cm2 current density was observed. In addition, carbon fiber has great promise as field emitter for MILOs. These results show that the carbon fiber cathodes can be utilized for electron emission in high power diodes with different structures.

  17. A series of tufted carbon fiber cathodes designed for different high power microwave sources.

    PubMed

    Liu, Lie; Li, Limin; Zhang, Jun; Zhang, Xiaoping; Wen, Jianchun; Liu, Yonggui

    2008-06-01

    We report the fabrication technique of tufted carbon fiber cathodes for different microwave sources. Three carbon fiber cathodes were constructed, including a planar cathode, an annular cathode, and a cylindrical cathode for radial emission. Experimental investigations on these cathodes were performed in a reflex triode virtual cathode oscillator (vircator), a backward wave oscillator (BWO), and a magnetically insulated transmission line oscillator (MILO), respectively. The pulse duration of microwave emission from the reflex triode vircator was lengthened by using the planar carbon fiber cathode. In the BWO with the annular carbon fiber cathode, the uniform electron beam with a kA/cm(2) current density was observed. In addition, carbon fiber has great promise as field emitter for MILOs. These results show that the carbon fiber cathodes can be utilized for electron emission in high power diodes with different structures.

  18. Multi-scale Rule-of-Mixtures Model of Carbon Nanotube/Carbon Fiber/Epoxy Lamina

    NASA Technical Reports Server (NTRS)

    Frankland, Sarah-Jane V.; Roddick, Jaret C.; Gates, Thomas S.

    2005-01-01

    A unidirectional carbon fiber/epoxy lamina in which the carbon fibers are coated with single-walled carbon nanotubes is modeled with a multi-scale method, the atomistically informed rule-of-mixtures. This multi-scale model is designed to include the effect of the carbon nanotubes on the constitutive properties of the lamina. It included concepts from the molecular dynamics/equivalent continuum methods, micromechanics, and the strength of materials. Within the model both the nanotube volume fraction and nanotube distribution were varied. It was found that for a lamina with 60% carbon fiber volume fraction, the Young's modulus in the fiber direction varied with changes in the nanotube distribution, from 138.8 to 140 GPa with nanotube volume fractions ranging from 0.0001 to 0.0125. The presence of nanotube near the surface of the carbon fiber is therefore expected to have a small, but positive, effect on the constitutive properties of the lamina.

  19. Laser cutting of carbon fiber reinforced thermo-plastics (CFRTP) by single-mode fiber laser irradiation

    NASA Astrophysics Data System (ADS)

    Niino, Hiroyuki; Kawaguchi, Yoshizo; Sato, Tadatake; Narazaki, Aiko; Kurosaki, Ryozo; Muramatsu, Mayu; Harada, Yoshihisa; Anzai, Kenji; Aoyama, Mitsuaki; Matsushita, Masafumi; Furukawa, Koichi; Nishino, Michiteru; Fujisaki, Akira; Miyato, Taizo; Kayahara, Takashi

    2014-03-01

    We report on the laser cutting of carbon fiber reinforced thermo-plastics (CFRTP) with a cw IR fiber laser (single-mode fiber laser, average power: 350 W). CFRTP is a high strength composite material with a lightweight, and is increasingly being used various applications. A well-defined cutting of CFRTP which were free of debris and thermal-damages around the grooves, were performed by the laser irradiation with a fast beam galvanometer scanning on a multiple-scanpass method.

  20. Oxidation Behavior of Carbon Fiber-Reinforced Composites

    NASA Technical Reports Server (NTRS)

    Sullivan, Roy M.

    2008-01-01

    OXIMAP is a numerical (FEA-based) solution tool capable of calculating the carbon fiber and fiber coating oxidation patterns within any arbitrarily shaped carbon silicon carbide composite structure as a function of time, temperature, and the environmental oxygen partial pressure. The mathematical formulation is derived from the mechanics of the flow of ideal gases through a chemically reacting, porous solid. The result of the formulation is a set of two coupled, non-linear differential equations written in terms of the oxidant and oxide partial pressures. The differential equations are solved simultaneously to obtain the partial vapor pressures of the oxidant and oxides as a function of the spatial location and time. The local rate of carbon oxidation is determined at each time step using the map of the local oxidant partial vapor pressure along with the Arrhenius rate equation. The non-linear differential equations are cast into matrix equations by applying the Bubnov-Galerkin weighted residual finite element method, allowing for the solution of the differential equations numerically.

  1. Lightning Strike Induced Damage Mechanisms of Carbon Fiber Composites

    NASA Astrophysics Data System (ADS)

    Kawakami, Hirohide

    Composite materials have a wide application in aerospace, automotive, and other transportation industries, because of the superior structural and weight performances. Since carbon fiber reinforced polymer composites possess a much lower electrical conductivity as compared to traditional metallic materials utilized for aircraft structures, serious concern about damage resistance/tolerance against lightning has been rising. Main task of this study is to clarify the lightning damage mechanism of carbon fiber reinforced epoxy polymer composites to help further development of lightning strike protection. The research on lightning damage to carbon fiber reinforced polymer composites is quite challenging, and there has been little study available until now. In order to tackle this issue, building block approach was employed. The research was started with the development of supporting technologies such as a current impulse generator to simulate a lightning strike in a laboratory. Then, fundamental electrical properties and fracture behavior of CFRPs exposed to high and low level current impulse were investigated using simple coupon specimens, followed by extensive parametric investigations in terms of different prepreg materials frequently used in aerospace industry, various stacking sequences, different lightning intensity, and lightning current waveforms. It revealed that the thermal resistance capability of polymer matrix was one of the most influential parameters on lightning damage resistance of CFRPs. Based on the experimental findings, the semi-empirical analysis model for predicting the extent of lightning damage was established. The model was fitted through experimental data to determine empirical parameters and, then, showed a good capability to provide reliable predictions for other test conditions and materials. Finally, structural element level lightning tests were performed to explore more practical situations. Specifically, filled-hole CFRP plates and patch

  2. RADIATION EFFECTS ON EPOXY/CARBON FIBER COMPOSITE

    SciTech Connect

    Hoffman, E; Eric Skidmore, E

    2008-12-12

    The Department of Energy Savannah River Site vitrifies nuclear waste incident to defense programs through its Defense Waste Processing Facility (DWPF). The piping in the DWPF seal pot jumper configuration must withstand the stresses during an unlikely but potential deflagration event, and maintain its safety function for a 20-year service life. Carbon fiber-reinforced epoxy composites (CFR) were proposed for protection and reinforcement of piping during such an event. The proposed CFR materials have been ASME-approved (Section XI, Code Case N-589-1) for post-construction maintenance and is DOT-compliant per 49CFR 192 and 195. The proposed carbon fiber/epoxy composite reinforcement system was originally developed for pipeline rehabilitation and post-construction maintenance in petrochemical, refineries, DOT applications and other industries. The effects of ionizing radiation on polymers and organic materials have been studied for many years. The majority of available data are based on traditional exposures to gamma irradiation at high dose rates ({approx}10,000 Gy/hr) allowing high total dose within reasonable test periods and general comparison of different materials exposed at such conditions. However, studies in recent years have shown that degradation of many polymers are sensitive to dose rate, with more severe degradation often observed at similar or even lower total doses when exposed to lower dose rates. This behavior has been primarily attributed to diffusion-limited oxidation which is minimized during very high dose rate exposures. Most test standards for accelerated aging and nuclear qualification of components acknowledge these limitations. The results of testing to determine the radiation resistance and microstructural effects of gamma irradiation exposure on a bisphenol-A based epoxy matrix composite reinforced with carbon fibers are presented. This work provides a foundation for a more extensive evaluation of dose rate effects on advanced epoxy

  3. Influence of metal-containing carbon fibers on the properties of carbon-filled plastics based on aromatic polyamide

    NASA Astrophysics Data System (ADS)

    Burya, A. I.; Safonova, A. M.; Rula, I. V.

    2012-07-01

    The influence of metal-containing carbon fibers on the thermal properties of carbon-filled phenylone-based plastics has been investigated. It has been shown that carbometallic fibers containing in their composition 20- 30 mass % of a finely dispersed metal (Co, Cu) are promising fillers of phenylone C-2 for making carbonfilled plastics working in frictional units of various machines and mechanisms.

  4. Strengthened PAN-based carbon fibers obtained by slow heating rate carbonization

    PubMed Central

    Kim, Min-A; Jang, Dawon; Tejima, Syogo; Cruz-Silva, Rodolfo; Joh, Han-Ik; Kim, Hwan Chul; Lee, Sungho; Endo, Morinobu

    2016-01-01

    Large efforts have been made over the last 40 years to increase the mechanical strength of polyacrylonitrile (PAN)-based carbon fibers (CFs) using a variety of chemical or physical protocols. In this paper, we report a new method to increase CFs mechanical strength using a slow heating rate during the carbonization process. This new approach increases both the carbon sp3 bonding and the number of nitrogen atoms with quaternary bonding in the hexagonal carbon network. Theoretical calculations support a crosslinking model promoted by the interstitial carbon atoms located in the graphitic interlayer spaces. The improvement in mechanical performance by a controlled crosslinking between the carbon hexagonal layers of the PAN based CFs is a new concept that can contribute further in the tailoring of CFs performance based on the understanding of their microstructure down to the atomic scale. PMID:27004752

  5. Laser ultrasound technology for fault detection on carbon fiber composites

    NASA Astrophysics Data System (ADS)

    Seyrkammer, Robert; Reitinger, Bernhard; Grün, Hubert; Sekelja, Jakov; Burgholzer, Peter

    2014-05-01

    The marching in of carbon fiber reinforced polymers (CFRPs) to mass production in the aeronautic and automotive industry requires reliable quality assurance methods. Laser ultrasound (LUS) is a promising nondestructive testing technique for sample inspection. The benefits compared to conventional ultrasound (US) testing are couplant free measurements and an easy access to complex shapes due to remote optical excitation and detection. Here the potential of LUS is present on composite test panels with relevant testing scenarios for industry. The results are evaluated in comparison to conventional ultrasound used in the aeronautic industry.

  6. Defect depth measurement of carbon fiber reinforced polymers by thermography

    NASA Astrophysics Data System (ADS)

    Chen, Terry Y.; Chen, Jian-Lun

    2016-01-01

    Carbon fiber reinforced polymers has been widely used in all kind of the industries. However the internal defects can result in the change of material or mechanical properties, and cause safety problem. In this study, step-heating thermography is employed to measure the time series temperature distribution of composite plate. The principle of heat conduction in a flat plate with defect inside is introduced. A temperature separation criterion to determine the depth of defect inside the specimen is obtained experimentally. Applying this criterion to CFRP specimens with embedded defects, the depth of embedded defect in CFRP can be determined quite well from the time series thermograms obtained experimentally.

  7. Damage-tolerant composite materials produced by stitching carbon fibers

    NASA Technical Reports Server (NTRS)

    Dow, Marvin B.; Smith, Donald L.

    1989-01-01

    NASA-Langley has undertaken the investigation of composite damage-tolerance enhancement and fabrication economies-maximization via reinforcement-stitching, in combination with resin transfer molding. Attention is given to results obtained by an experimental evaluation of composites tailored for damage tolerance by stitching layers of dry carbon-fiber fabric with closely-spaced threads, in order to furnish through-the-thickness reinforcement. Various stitching patterns and thread materials have been evaluated, using flat-plate specimens; blade-stiffened structural elements have been fabricated and tested. The results presented indicate that stitched laminates furnish damage tolerance performance comparable to that of more expensive, toughened-matrix composites.

  8. A carbonyl iron/carbon fiber material for electromagnetic wave absorption.

    PubMed

    Youh, Meng-Jey; Wu, Hung-Chih; Lin, Wang-Hua; Chiu, Sheng-Cheng; Huang, Chien-Fa; Yu, Hsin-Chih; Hsu, Jen-Sung; Li, Yuan-Yao

    2011-03-01

    A carbonyl iron/carbon fiber material consisting of carbon fibers grown on micrometer-sized carbonyl iron sphere, was synthesized by chemical vapor deposition using a mixture of C2H2 and H2. The hollow-core carbon fibers (outer diameter: 140 nm and inner diameter: 40 nm) were composed of well-ordered graphene layers which were almost parallel to the long axis of the fibers. A composite (2 mm thick) consisting of the carbonyl iron/carbon fibers and epoxy resin demonstrated excellent electromagnetic (EM) wave absorption. Minimum reflection losses of -36 dB (99.95% of EM wave absorption) at 7.6 GHz and -32 dB (99.92% of EM wave absorption) at 34.1 GHz were achieved. The well-dispersed and network-like carbon fibers in the resin matrix affected the dielectric loss of the EM wave while the carbonyl iron affected the magnetic loss.

  9. Hybrid carbon fiber/carbon nanotube composites for structural damping applications.

    PubMed

    Tehrani, M; Safdari, M; Boroujeni, A Y; Razavi, Z; Case, S W; Dahmen, K; Garmestani, H; Al-Haik, M S

    2013-04-19

    Carbon nanotubes (CNTs) were grown on the surface of carbon fibers utilizing a relatively low temperature synthesis technique; graphitic structures by design (GSD). To probe the effects of the synthesis protocols on the mechanical properties, other samples with surface grown CNTs were prepared using catalytic chemical vapor deposition (CCVD). The woven graphite fabrics were thermally shielded with a thin film of SiO2 and CNTs were grown on top of this film. Raman spectroscopy and electron microscopy revealed the grown species to be multi-walled carbon nanotubes (MWCNTs). The damping performance of the hybrid CNT-carbon fiber-reinforced epoxy composite was examined using dynamic mechanical analysis (DMA). Mechanical testing confirmed that the degradations in the strength and stiffness as a result of the GSD process are far less than those encountered through using the CCVD technique and yet are negligible compared to the reference samples. The DMA results indicated that, despite the minimal degradation in the storage modulus, the loss tangent (damping) for the hybrid composites utilizing GSD-grown MWCNTs improved by 56% compared to the reference samples (based on raw carbon fibers with no surface treatment or surface grown carbon nanotubes) over the frequency range 1-60 Hz. These results indicated that the energy dissipation in the GSD-grown MWCNTs composite can be primarily attributed to the frictional sliding at the nanotube/epoxy interface and to a lesser extent to the stiff thermal shielding SiO2 film on the fiber/matrix interface. PMID:23518871

  10. Carbon Nanotubes Growth by CVD on Graphite Fibers

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Cochrane, J. C.; Lehoczky, S. L.; Muntele, I.; Ila, D.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Due to the superior electrical and mechanical properties of carbon nanotubes (CNT), synthesizing CNT on various substances for electronics devices and reinforced composites have been engaged in many efforts for applications. This presentation will illustrate CNT synthesized on graphite fibers by thermal CVD. On the fiber surface, iron nanoparticles as catalysts for CNT growth are coated. The growth temperature ranges from 600 to 1000 C and the pressure ranges from 100 Torr to one atmosphere. Methane and hydrogen gases with methane content of 10% to 100% are used for the CNT synthesis. At high growth temperatures (greater than or equal to 900 C), the rapid inter-diffusion of the transition metal iron on the graphite surface results in the rough fiber surface without any CNT grown on it. When the growth temperature is relative low (650-800 C), CNT with catalytic particles on the nanotube top ends are fabricated on the graphite surface. (Methane and hydrogen gases with methane content of 10% to 100% are used for the CNT synthesis.) (By measuring the samples) Using micro Raman spectroscopy in the breath mode region, single-walled or multi-walled CNT (MWCNT), depending on growth concentrations, are found. Morphology, length and diameter of these MWCNT are determined by scanning electron microscopy and Raman spectroscopy. The detailed results of syntheses and characterizations will be discussed in the presentation.

  11. Oxidation Behavior of Carbon Fiber Reinforced Silicon Carbide Composites

    NASA Technical Reports Server (NTRS)

    Valentin, Victor M.

    1995-01-01

    Carbon fiber reinforced Silicon Carbide (C-SiC) composites offer high strength at high temperatures and good oxidation resistance. However, these composites present some matrix microcracks which allow the path of oxygen to the fiber. The aim of this research was to study the effectiveness of a new Silicon Carbide (SiC) coating developed by DUPONT-LANXIDE to enhance the oxidation resistance of C-SiC composites. A thermogravimetric analysis was used to determine the oxidation rate of the samples at different temperatures and pressures. The Dupont coat proved to be a good protection for the SiC matrix at temperatures lower than 1240 C at low and high pressures. On the other hand, at temperatures above 1340 C the Dupont coat did not seem to give good protection to the composite fiber and matrix. Even though some results of the tests have been discussed, because of time restraints, only a small portion of the desired tests could be completed. Therefore, no major conclusions or results about the effectiveness of the coat are available at this time.

  12. Adsorption dynamics of trichlorofluoromethane in activated carbon fiber beds.

    PubMed

    Zhang, Xiaoping; Zhao, Xin; Hu, Jiaqi; Wei, Chaohai; Bi, Hsiaotao T

    2011-02-28

    Adsorption on carbon fixed-beds is considered as an inexpensive and highly effective way for controlling chlorofluorocarbons (CFCs) emissions. In the present work, a dynamic model under constant-pattern wave conditions has been developed to predict the breakthrough behavior of trichlorofluoromethane (CFC-11) adsorption in a fixed bed packed with activated carbon fibers (ACFs). The adsorption of CFC-11 vapor onto viscose-based ACFs was performed in a fixed bed at different test conditions. The results showed that, in a deep bed (>120 mm), the analytical model based on the external mass transfer with the Langmuir isotherm could describe the adsorption dynamics well. The model parameters, the characteristic breakthrough time and the film mass-transfer coefficients are related to such operating parameters as the superficial gas velocity, feed concentration and bed height. It was found from the breakthrough dynamics that the mass transfer from the fluid phase to the fiber surface dominated the CFC-11 adsorption onto ACFs in fixed beds.

  13. Creep rupture testing of carbon fiber-reinforced epoxy composites

    NASA Astrophysics Data System (ADS)

    Burton, Kathryn Anne

    Carbon fiber is becoming more prevalent in everyday life. As such, it is necessary to have a thorough understanding of, not solely general mechanical properties, but of long-term material behavior. Creep rupture testing of carbon fiber is very difficult due to high strength and low strain to rupture properties. Past efforts have included testing upon strands, single tows and overwrapped pressure vessels. In this study, 1 inch wide, [0°/90°]s laminated composite specimens were constructed from fabric supplied by T.D. Williamson Inc. Specimen fabrication methods and gripping techniques were investigated and a method was developed to collect long term creep rupture behavior data. An Instron 1321 servo-hydraulic material testing machine was used to execute static strength and short term creep rupture tests. A hanging dead-weight apparatus was designed to perform long-term creep rupture testing. The testing apparatus, specimens, and specimen grips functioned well. Collected data exhibited a power law distribution and therefore, a linear trend upon a log strength-log time plot. Statistical analysis indicated the material exhibited slow degradation behavior, similar to previous studies, and could maintain a 50 year carrying capacity at 62% of static strength, approximately 45.7 ksi.

  14. Adsorption dynamics of trichlorofluoromethane in activated carbon fiber beds.

    PubMed

    Zhang, Xiaoping; Zhao, Xin; Hu, Jiaqi; Wei, Chaohai; Bi, Hsiaotao T

    2011-02-28

    Adsorption on carbon fixed-beds is considered as an inexpensive and highly effective way for controlling chlorofluorocarbons (CFCs) emissions. In the present work, a dynamic model under constant-pattern wave conditions has been developed to predict the breakthrough behavior of trichlorofluoromethane (CFC-11) adsorption in a fixed bed packed with activated carbon fibers (ACFs). The adsorption of CFC-11 vapor onto viscose-based ACFs was performed in a fixed bed at different test conditions. The results showed that, in a deep bed (>120 mm), the analytical model based on the external mass transfer with the Langmuir isotherm could describe the adsorption dynamics well. The model parameters, the characteristic breakthrough time and the film mass-transfer coefficients are related to such operating parameters as the superficial gas velocity, feed concentration and bed height. It was found from the breakthrough dynamics that the mass transfer from the fluid phase to the fiber surface dominated the CFC-11 adsorption onto ACFs in fixed beds. PMID:21216098

  15. Oxidation of carbon fiber surfaces for use as reinforcement in high-temperature cementitious material systems

    DOEpatents

    Sugama, Toshifumi.

    1990-05-22

    The interfacial bond characteristics between carbon fiber and a cement matrix, in high temperature fiber-reinforced cementitious composite systems, can be improved by the oxidative treatment of the fiber surfaces. Compositions and the process for producing the compositions are disclosed. 2 figs.

  16. Oxidation of carbon fiber surfaces for use as reinforcement in high-temperature cementitious material systems

    DOEpatents

    Sugama, Toshifumi

    1990-01-01

    The interfacial bond characteristics between carbon fiber and a cement matrix, in high temperature fiber-reinforced cementitious composite systems, can be improved by the oxidative treatment of the fiber surfaces. Compositions and the process for producing the compositions are disclosed.

  17. The transfer of carbon fibers through a commercial aircraft water separator and air cleaner

    NASA Technical Reports Server (NTRS)

    Meyers, J. A.

    1979-01-01

    The fraction of carbon fibers passing through a water separator and an air filter was determined in order to estimate the proportion of fibers outside a closed aircraft that are transmitted to the electronics through the air conditioning system. When both devices were used together and only fibers 3 mm or larger were considered, a transfer function of .001 was obtained.

  18. Processes for preparing carbon fibers using sulfur trioxide in a halogenated solvent

    SciTech Connect

    Patton, Jasson T.; Barton, Bryan E.; Bernius, Mark T.; Chen, Xiaoyun; Hukkanen, Eric J.; Rhoton, Christina A.; Lysenko, Zenon

    2015-12-29

    Disclosed here are processes for preparing carbonized polymers (preferably carbon fibers), comprising sulfonating a polymer with a sulfonating agent that comprises SO.sub.3 dissolved in a solvent to form a sulfonated polymer; treating the sulfonated polymer with a heated solvent, wherein the temperature of the solvent is at least 95.degree. C.; and carbonizing the resulting product by heating it to a temperature of 500-3000.degree. C. Carbon fibers made according to these methods are also disclosed herein.

  19. Bond strength of individual carbon nanotubes grown directly on carbon fibers

    NASA Astrophysics Data System (ADS)

    Kim, Kyoung Ju; Lee, Geunsung; Kim, Sung-Dae; Kim, Seong-Il; Youk, Ji Ho; Lee, Jinyong; Kim, Young-Woon; Yu, Woong-Ryeol

    2016-10-01

    The performance of carbon nanotube (CNT)-based devices strongly depends on the adhesion of CNTs to the substrate on which they were directly grown. We report on the bond strength of CNTs grown on a carbon fiber (T700SC Toray), measured via in situ pulling of individual CNTs inside a transmission electron microscope. The bond strength of an individual CNT, obtained from the measured pulling force and CNT cross-section, was very high (˜200 MPa), 8-10 times higher than that of an adhesion model assuming only van der Waals interactions (25 MPa), presumably due to carbon-carbon interactions between the CNT (its bottom atoms) and the carbon substrate.

  20. Bond strength of individual carbon nanotubes grown directly on carbon fibers.

    PubMed

    Kim, Kyoung Ju; Lee, Geunsung; Kim, Sung-Dae; Kim, Seong-Il; Youk, Ji Ho; Lee, Jinyong; Kim, Young-Woon; Yu, Woong-Ryeol

    2016-10-01

    The performance of carbon nanotube (CNT)-based devices strongly depends on the adhesion of CNTs to the substrate on which they were directly grown. We report on the bond strength of CNTs grown on a carbon fiber (T700SC Toray), measured via in situ pulling of individual CNTs inside a transmission electron microscope. The bond strength of an individual CNT, obtained from the measured pulling force and CNT cross-section, was very high (∼200 MPa), 8-10 times higher than that of an adhesion model assuming only van der Waals interactions (25 MPa), presumably due to carbon-carbon interactions between the CNT (its bottom atoms) and the carbon substrate.

  1. Bond strength of individual carbon nanotubes grown directly on carbon fibers.

    PubMed

    Kim, Kyoung Ju; Lee, Geunsung; Kim, Sung-Dae; Kim, Seong-Il; Youk, Ji Ho; Lee, Jinyong; Kim, Young-Woon; Yu, Woong-Ryeol

    2016-10-01

    The performance of carbon nanotube (CNT)-based devices strongly depends on the adhesion of CNTs to the substrate on which they were directly grown. We report on the bond strength of CNTs grown on a carbon fiber (T700SC Toray), measured via in situ pulling of individual CNTs inside a transmission electron microscope. The bond strength of an individual CNT, obtained from the measured pulling force and CNT cross-section, was very high (∼200 MPa), 8-10 times higher than that of an adhesion model assuming only van der Waals interactions (25 MPa), presumably due to carbon-carbon interactions between the CNT (its bottom atoms) and the carbon substrate. PMID:27581367

  2. Delamination behavior of carbon fiber/epoxy composite laminates with short fiber reinforcement

    SciTech Connect

    Sohn, M.S.; Hu, X.Z. . Dept. of Mechanical and Materials Engineering)

    1994-06-01

    Delamination in laminated materials is one major mode of damage and failure encountered in application. Fracture mechanics is often used to characterize the interlaminar fracture behavior. The interlaminar fracture energies, G[sub I], G[sub II] and G[sub I/II] are the major concerns to characterize the interlaminar toughness of the composite laminates. Typical mode-I fracture is caused by normal tension, and typical mode-II fracture by shear in the direction of crack extension. The objective of the present study is to compare and discuss the mode-I and mode-II interlaminar fracture energies, G[sub I] and G[sub II] of carbon fiber/epoxy composite laminates with and without the reinforcement of short Kevlar fibers (5--7 mm in length) and to identify the microfracture features of the Kevlar fibers under those two delamination modes through SEM observations. Double cantilever beam (DCB) specimens and end notched flexure (ENF) specimens are used for the mode-I and -II delamination experiments.

  3. Carbyne fiber synthesis within evaporating metallic liquid carbon

    SciTech Connect

    Cannella, Christopher B.; Goldman, Nir

    2015-07-09

    Carbyne (e.g., linear chains of sp-bonded carbon) has been the subject of intense research focus due to its presence in astrophysical bodies, as well as its potential for use as a nanoelectronic device and superhard material. In this work, we discuss the formation of carbyne fiber bundles over a nanosecond time scale in laser pulse melting studies, using a previously determined density functional tight binding model for carbon coupled with a new correction for the dispersion energy. We determine our dispersion energy model by optimizing a modified Lennard-Jones potential to an experimentally determined equation of state for graphite, yielding excellent results for the bulk modulus and density under ambient conditions. We then simulate previous experiments by heating graphite to high temperature, followed by expanding the ensuing liquid phase to low density. Our results indicate that the initial, hot liquid phase mainly consists of sp2-bonded carbon atoms, which form a system of sp-bonded strands bound together via dispersion interactions upon achieving low density and temperature. Lastly, the high computational efficiency of our approach allows for direct comparison with experiments that span a wide range of thermodynamic conditions and can help determine parameters for synthesis of carbon-based materials with potentially exotic properties.

  4. Carbyne fiber synthesis within evaporating metallic liquid carbon

    DOE PAGES

    Cannella, Christopher B.; Goldman, Nir

    2015-07-09

    Carbyne (e.g., linear chains of sp-bonded carbon) has been the subject of intense research focus due to its presence in astrophysical bodies, as well as its potential for use as a nanoelectronic device and superhard material. In this work, we discuss the formation of carbyne fiber bundles over a nanosecond time scale in laser pulse melting studies, using a previously determined density functional tight binding model for carbon coupled with a new correction for the dispersion energy. We determine our dispersion energy model by optimizing a modified Lennard-Jones potential to an experimentally determined equation of state for graphite, yielding excellentmore » results for the bulk modulus and density under ambient conditions. We then simulate previous experiments by heating graphite to high temperature, followed by expanding the ensuing liquid phase to low density. Our results indicate that the initial, hot liquid phase mainly consists of sp2-bonded carbon atoms, which form a system of sp-bonded strands bound together via dispersion interactions upon achieving low density and temperature. Lastly, the high computational efficiency of our approach allows for direct comparison with experiments that span a wide range of thermodynamic conditions and can help determine parameters for synthesis of carbon-based materials with potentially exotic properties.« less

  5. Ceramic silicon-boron-carbon fibers from organic silicon-boron-polymers

    NASA Technical Reports Server (NTRS)

    Riccitiello, Salvatore R. (Inventor); Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

    1993-01-01

    Novel high strength ceramic fibers derived from boron, silicon, and carbon organic precursor polymers are discussed. The ceramic fibers are thermally stable up to and beyond 1200 C in air. The method of preparation of the boron-silicon-carbon fibers from a low oxygen content organosilicon boron precursor polymer of the general formula Si(R2)BR(sup 1) includes melt-spinning, crosslinking, and pyrolysis. Specifically, the crosslinked (or cured) precursor organic polymer fibers do not melt or deform during pyrolysis to form the silicon-boron-carbon ceramic fiber. These novel silicon-boron-carbon ceramic fibers are useful in high temperature applications because they retain tensile and other properties up to 1200 C, from 1200 to 1300 C, and in some cases higher than 1300 C.

  6. Effects of carbon/graphite fiber contamination on high voltage electrical insulation

    NASA Technical Reports Server (NTRS)

    Garrity, T.; Eichler, C.

    1980-01-01

    The contamination mechanics and resulting failure modes of high voltage electrical insulation due to carbon/graphite fibers were examined. The high voltage insulation vulnerability to carbon/graphite fiber induced failure was evaluated using a contamination system which consisted of a fiber chopper, dispersal chamber, a contamination chamber, and air ducts and suction blower. Tests were conducted to evaluate the effects of fiber length, weathering, and wetness on the insulator's resistance to carbon/graphite fibers. The ability of nuclear, fossil, and hydro power generating stations to maintain normal power generation when the surrounding environment is contaminated by an accidental carbon fiber release was investigated. The vulnerability assessment included only the power plant generating equipment and its associated controls, instrumentation, and auxiliary and support systems.

  7. Mesophase pitch-based carbon fiber for improved inflammability of CFRP

    SciTech Connect

    Nakagoshi, Akira; Tomonoh, Shigeki; Sakamoto, Yosihiro

    1995-10-01

    Carbon Fiber Reinforced Plastics (CFRP) are extensively used because of their favorable physical properties such as high strength-to-weight ratio and small thermal expansion. However, flammability of CFRP has limited their application especially in the transportation and industrial field. Exposed to flame, CFRP laminates made of PAN-based carbon fibers burst into flame in short time, while CFRP laminates made from mesophase pitch-based carbon fibers don`t burst into flame. This paper describes the experimental results of local heating test by gas burner. When the flame temperature was 1,000 C, a CFRP laminate made from PAN-based carbon fiber burned within 40 sec. Under the same condition, a CFRP laminate made from mesophase pitch-based carbon fiber didn`t burn in 10 min. The matrix resin of both laminates was 250 F curable epoxy resin. This behavior mainly depends upon the thermal conductivity of the carbon fibers. The mesophase pitch-based carbon fibers have high thermal conductivity, so they can diffuse thermal energy and lower laminate surface temperature. On the other hand, PAN-based carbon fibers have low thermal conductivity, so they can`t diffuse thermal energy enough, and the laminates made from them burn easily. Mechanical properties of CFRP during local heating test in comparison with Aluminum plate are also discussed.

  8. [Modification of activated carbon fiber for electro-Fenton degradation of phenol].

    PubMed

    Ma, Nan; Tian, Yao-Jin; Yang, Guang-Ping; Xie, Xin-Yuan

    2014-07-01

    Microwave-modified activated carbon fiber (ACF-1), nitric acid-modified activated carbon fiber (ACF-2), phosphoric acid-modified activated carbon fiber (ACF-3) and ammonia-modified activated carbon fiber (ACF-4) were successfully fabricated. The electro-Fenton catalytic activities of modified activated carbon fiber were evaluated using phenol as a model pollutant. H2O2 formation, COD removal efficiency and phenol removal efficiency were investigated compared with the unmodified activated carbon fiber (ACF-0). Results indicated that ACF-1 showed the best adsorption and electrocatalytic activity. Modification was in favor of the formation of H2O2. The performance of different systems on phenol degradation and COD removal were ACF-1 > ACF-3 > ACF-4 > ACF-2 > ACF-0 and ACF-1 > ACF-4 > ACF-3 > ACF-2 > ACF-0, respectively, which confirmed that electrocatalytic activities of modified activated carbon fiber were better than the unmodified. In addition, phenol intermediates were not the same while using different modified activated carbon fibers.

  9. A Silicon detector system on carbon fiber support at small radius

    SciTech Connect

    Marvin E. Johnson

    2004-04-28

    The design of a silicon detector for a p{bar p} collider experiment will be described. The detector uses a carbon fiber support structure with sensors positioned at small radius with respect to the beam. A brief overview of the mechanical design is given. The emphasis is on the electrical characteristics of the detector. General principles involved in grounding systems with carbon fiber structures will be covered. The electrical characteristics of the carbon fiber support structure will be presented. Test results imply that carbon fiber must be regarded as a conductor for the frequency region of interest of 10 to 100 MHz. No distinction is found between carbon fiber and copper. Performance results on noise due to pick-up through the low mass fine pitch cables carrying the analogue signals and floating metal is discussed.

  10. Treatment of Lignin Precursors to Improve their Suitability for Carbon Fibers: A Literature Review

    SciTech Connect

    Paul, Ryan; Naskar, Amit; Gallego, Nidia; Dai, Xuliang; Hausner, Andrew

    2015-04-17

    Lignin has been investigated as a carbon fiber precursor since the 1960s. Although there have been a number of reports of successful lignin-based carbon fiber production at the lab scale, lignin-based carbon fibers are not currently commercially available. This review will highlight some of the known challenges, and also the reported methods for purifying and modifying lignin to improve it as a precursor. Lignin can come from different sources (e.g. hardwood, softwood, grasses) and extraction methods (e.g. organosolv, kraft), meaning that lignin can be found with a diversity of purity and structure. The implication of these conditions on lignin as carbon fiber precursor is not comprehensively known, especially as the lignin landscape is evolving. The work presented in this review will help guide the direction of a project between GrafTech and ORNL to develop lignin carbon fiber technology, as part of a cooperative agreement with the DOE Advanced Manufacturing Office.

  11. Effects of EB irradiation on stress-strain curves for carbon fiber reinforced composite materials

    NASA Astrophysics Data System (ADS)

    Kobayashi, H.; Yamada, K.; Mizutani, A.; Uchida, N.; Tanaka, K.; Nishi, Yoshitake

    2004-02-01

    In order to evaluate influence of electron beam (EB) irradiation on elasticity and stress- strain curve of composite materials reinforced by carbon fiber (CF), carbon fiber reinforced polymer (CFRP) and carbon fiber reinforced graphite (C/C) were treated by EB irradiation of 0.3 MGy. Since the EB strengthening was mainly dominated by the ductility enhancements of carbon fiber and matrix of epoxy resin, EB irradiation enlarged fracture stress and enhanced fracture strain of CFRP. Furthermore, EB irradiation slightly enhanced bending elasticity of CFRP and largely enhanced the initial spring constant related to elasticity of C/C coil. Although the elasticity enhancement of carbon fibers did not largely contribute that of CFRP, that of treated graphite matrix in C/C mainly caused the C/C coil elasticity enhancement by EB irradiation. Such a new treatment is a dream-worthy technology for structural materials to be applied in the fields of future engineering.

  12. TECHNICAL NOTE: Design and development of electromagnetic absorbers with carbon fiber composites and matching dielectric layers

    NASA Astrophysics Data System (ADS)

    Neo, C. P.; Varadan, V. K.

    2001-10-01

    Radar absorbing materials are designed and developed with carbon fibers and suitable matching layers. Complex permittivities of carbon fiber composite are predicted on the basis that the modulus of permittivity obeys a logarithmic law of mixtures and the dielectric loss tangents are related through a linear law of mixtures. Linear regression analysis performed on the data points provides the constants which are used to predict the effective permittivities of carbon fiber composite at different frequencies. Using the free space measurement system, complex permittivities of the lossy dielectric at different frequencies are obtained. These complex permittivities are used to predict the reflectivity of a thin lossy dielectric layer on carbon fiber composite substrate. The predicted results agree quite well with the measured data. It is interesting to note that the thin lossy dielectric layer, about 0.03 mm thick, has helped to reduce the reflectivity of the 5.2 mm thick carbon fiber composite considerably.

  13. Influence of locational states of submicron fibers added into matrix on mechanical properties of plain-woven Carbon Fiber Composite

    NASA Astrophysics Data System (ADS)

    Kumamoto, Soichiro; Okubo, Kazuya; Fujii, Toru

    2016-01-01

    The aim of this study was to show the influence of locational states of submicron fibers added into epoxy matrix on mechanical properties of modified plane-woven carbon fiber reinforced plastic (CFRP). To change the locational states of submicron fibers, two kinds of fabrication processes were applied in preparing specimen by hand lay-up method. Submicron fibers were simply added into epoxy resin with ethanol after they were stirred by a dispersion process using homogenizer to be located far from the interface between reinforcement and matrix. In contrast, submicron fibers were attached onto the carbon fibers by injecting from a spray nozzle accompanying with ethanol to be located near the interface, after they were tentatively contained in ethanol. The plain-woven CFRP plates were fabricated by hand lay-up method and cured at 80 degree-C for 1 hour and then at 150 degree-C for 3 hours. After curing, the plain-woven CFRP plates were cut into the dimension of specimen. Tensile shear strength and Mode-II fracture toughness of CFRP were determined by tensile lap-shear test and End-notched flexure(ENF) test, respectively. When submicron fibers were located far from the interface between carbon fibers and epoxy resin, tensile shear strength and Mode-II fracture toughness of CFRP were improved 30% and 18% compared with those of unmodified case. The improvement ratio in modified case was rather low (about few percentages) in the case where submicron fibers were located near the interface. The result suggested that crack propagation should be prevented when submicron fibers were existed far from the interface due to the effective stress state around the crack tip.

  14. Isothermal and hygrothermal agings of hybrid glass fiber/carbon fiber composite

    NASA Astrophysics Data System (ADS)

    Barjasteh, Ehsan

    New applications of fiber-reinforced polymer composites (FRPCs) are arising in non-traditional sectors of industry, such as civil infrastructure, automotive, and power distribution. For example, composites are being used in place of steel to support high-voltage overhead conductors. In this application, conductive strands of aluminum are wrapped around a solid composite rod comprised of unidirectional carbon and glass fibers in an epoxy matrix, which is commercially called ACCC conductor. Composite-core conductors such as these are expected to eventually replace conventional steel-reinforced conductors because of the reduced sag at high temperatures, lower weight, higher ampacity, and reduced line losses. Despite the considerable advantages in mechanical performance, long-term durability of composite conductors is a major concern, as overhead conductors are expected to retain properties (with minimal maintenance) over a service life that spans multiple decades. These concerns stem from the uncertain effects of long-term environmental exposure, which includes temperature, moisture, radiation, and aggressive chemicals, all of which can be exacerbated by cyclic loads. In general, the mechanical and physical properties of polymer composites are adversely affected by such environmental factors. Consequently, the ability to forecast changes in material properties as a function of environmental exposure, particularly bulk mechanical properties, which are affected by the integrity of fiber-matrix interfaces, is required to design for extended service lives. Polymer composites are susceptible to oxidative degradation at high temperatures approaching but not quite reaching the glass transition temperature ( Tg). Although the fibers are stable at such temperatures, the matrix and especially the fiber-matrix interface can undergo degradation that affects the physical and mechanical properties of the structure over time. Therefore, as a first step, the thermal aging of an

  15. Electron-spin-resonance studies of vapor-grown carbon fibers

    NASA Technical Reports Server (NTRS)

    Marshik, B.; Meyer, D.; Apple, T.

    1987-01-01

    The effects of annealing temperature and fiber diameter on the degree of disorder of vapor-grown carbon fibers were investigated by analyzing the electron-spin-resonance (ESR) line shapes of fibers annealed at six various temperatures up to 3375 K. The diameter of fibers, grown from methane gas, ranged from 10 to 140 microns with most fibers between 20 and 50 microns. It was found that the degree of disorder of vapor-grown fibers decreases upon annealing to higher temperature; standard angular deviation between the fiber axis and the crystallite basal planes could vary from 35 deg (for annealing temperature of 2275 K) to 12 deg (for 3375 K). With respect to fiber diameter, order parameters were found to be higher for fibers of smaller diameters.

  16. Radio-frequency and microwave load comprising a carbon-bonded carbon fiber composite

    DOEpatents

    Lauf, Robert J.; McMillan, April D.; Johnson, Arvid C.; Everleigh, Carl A.; Moorhead, Arthur J.

    1998-01-01

    A billet of low-density carbon-bonded carbon fiber (CBCF) composite is machined into a desired attenuator or load element shape (usually tapering). The CBCF composite is used as a free-standing load element or, preferably, brazed to the copper, brass or aluminum components of coaxial transmission lines or microwave waveguides. A novel braze method was developed for the brazing step. The resulting attenuator and/or load devices are robust, relatively inexpensive, more easily fabricated, and have improved performance over conventional graded-coating loads.

  17. Effect of doping of multi-walled carbon nanotubes on phenolic based carbon fiber reinforced nanocomposites

    NASA Astrophysics Data System (ADS)

    Saeed, Sadaf; Hakeem, Saira; Faheem, Muhammad; Alvi, Rashid Ahmed; Farooq, Khawar; Tajammul Hussain, Syed; Nisar Ahmad, Shahid

    2013-06-01

    We report on the effect of multi-walled carbon nanotubes (MWCNTs) on different properties of phenolic resin. A low content of MWCNTs (~ 0.05 wt%) was mixed in phenolic resin and a stable dispersion was achieved by ultrasonication, followed by melt mixing. After curing the characterization of these composites was done by using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transform infra-red spectroscopy (FTIR). The thermal and ablative properties of carbon fiber reinforced MWCNTs-phenolic nanocomposites were also studied. The addition of MWCNTs showed improvement in thermal stability and ablation properties.

  18. Radio-frequency and microwave load comprising a carbon-bonded carbon fiber composite

    DOEpatents

    Lauf, R.J.; McMillan, A.D.; Johnson, A.C.; Everleigh, C.A.; Moorhead, A.J.

    1998-04-21

    A billet of low-density carbon-bonded carbon fiber (CBCF) composite is machined into a desired attenuator or load element shape (usually tapering). The CBCF composite is used as a free-standing load element or, preferably, brazed to the copper, brass or aluminum components of coaxial transmission lines or microwave waveguides. A novel braze method was developed for the brazing step. The resulting attenuator and/or load devices are robust, relatively inexpensive, more easily fabricated, and have improved performance over conventional graded-coating loads. 9 figs.

  19. [Adsorption kinetics of reactive dyes on activated carbon fiber].

    PubMed

    Li, Ying; Yue, Qin-Yan; Gao, Bao-Yu; Yang, Jing; Zheng, Yan

    2007-11-01

    The adsorption capability of activated carbon fiber (ACF) to four reactive dyes (reactive brilliant red K-2BP, reactive turquoise blue KN-G, reactive golden yellow K-3RP, reactive black KN-B) in aqueous solution was studied, and adsorption mechanism was focused on from kinetics point of view. The results show that the equilibrium adsorbing capacity (q(e)) of each dye increases with the addition of initial concentration or temperature. On the same condition, the order of q(e) is: reactive brilliant red > reactive golden yellow > reactive black > reactive turquoise blue. The adsorption processes follow a pseudo second-order kinetic rate equation, and the steric structure, size and polarity of dyes are important influence factors to initial adsorption rate. The adsorption activation energy of each dye is low (16.42, 3.56, 5.21, 26.38 kJ x mol(-1) respectively), which indicates that it belongs to physics adsorption.

  20. Metal-bonded, carbon fiber-reinforced composites

    DOEpatents

    Sastri, Suri A.; Pemsler, J. Paul; Cooke, Richard A.; Litchfield, John K.; Smith, Mark B.

    1996-01-01

    Metal bonded carbon fiber-reinforced composites are disclosed in which the metal and the composite are strongly bound by (1) providing a matrix-depleted zone in the composite of sufficient depth to provide a binding site for the metal to be bonded and then (2) infiltrating the metal into the matrix-free zone to fill a substantial portion of the zone and also provide a surface layer of metal, thereby forming a strong bond between the composite and the metal. The invention also includes the metal-bound composite itself, as well as the provision of a coating over the metal for high-temperature performance or for joining to other such composites or to other substrates.

  1. Radiation effects on epoxy/carbon-fiber composite

    NASA Astrophysics Data System (ADS)

    Hoffman, E. N.; Skidmore, T. E.

    2009-07-01

    Carbon fiber-reinforced bisphenol-A epoxy matrix composite was evaluated for gamma radiation resistance. The composite was exposed to total gamma doses of 0.5, 1.0, and 2.0 MGy. Irradiated and baseline samples were tested for tensile strength, hardness and evaluated using Fourier transform infra-red spectroscopy and differential scanning calorimetry for structural changes. Scanning electron microscopy was used to evaluate microstructural behavior. Mechanical testing of the composite bars revealed no apparent change in modulus, strain to failure, or fracture strength after exposures. However, testing of only the epoxy matrix revealed changes in hardness, thermal properties, and spectroscopy results with increasing gamma irradiation. The results quantify the changes in the epoxy within the composite as a result of exposure to gamma radiation at doses relevant to service.

  2. Metal-bonded, carbon fiber-reinforced composites

    DOEpatents

    Sastri, S.A.; Pemsler, J.P.; Cooke, R.A.; Litchfield, J.K.; Smith, M.B.

    1996-03-05

    Metal bonded carbon fiber-reinforced composites are disclosed in which the metal and the composite are strongly bound by (1) providing a matrix-depleted zone in the composite of sufficient depth to provide a binding site for the metal to be bonded and then (2) infiltrating the metal into the matrix-free zone to fill a substantial portion of the zone and also provide a surface layer of metal, thereby forming a strong bond between the composite and the metal. The invention also includes the metal-bound composite itself, as well as the provision of a coating over the metal for high-temperature performance or for joining to other such composites or to other substrates. 2 figs.

  3. Large-aperture active optical carbon fiber reinforced polymer mirror

    NASA Astrophysics Data System (ADS)

    Jungwirth, Matthew E. L.; Wilcox, Christopher C.; Wick, David V.; Baker, Michael S.; Hobart, Clinton G.; Milinazzo, Jared J.; Robichaud, Joseph; Romeo, Robert C.; Martin, Robert N.; Ballesta, Jerome; Lavergne, Emeric; Dereniak, Eustace L.

    2013-05-01

    An active reflective component can change its focal length by physically deforming its reflecting surface. Such elements exist at small apertures, but have yet to be fully realized at larger apertures. This paper presents the design and initial results of a large-aperture active mirror constructed of a composite material called carbon fiber reinforced polymer (CFRP). The active CFRP mirror uses a novel actuation method to change radius of curvature, where actuators press against two annular rings placed on the mirror's back. This method enables the radius of curvature to increase from 2000mm to 2010mm. Closed-loop control maintains good optical performance of 1.05 waves peak-to-valley (with respect to a HeNe laser) when the active CFRP mirror is used in conjunction with a commercial deformable mirror.

  4. Biohybrid Carbon Nanotube/Agarose Fibers for Neural Tissue Engineering

    PubMed Central

    Lewitus, Dan Y.; Landers, John; Branch, Jonathan; Smith, Karen L.; Callegari, Gerardo

    2011-01-01

    We report a novel approach for producing carbon nanotube fibers (CNF) composed with the polysaccharide agarose. Current attempts to make CNF’s require the use of a polymer or precipitating agent in the coagulating bath that may have negative effects in biomedical applications. We show that by taking advantage of the gelation properties of agarose one can substitute the bath with distilled water or ethanol and hence reduce the complexity associated with alternating the bath components or the use of organic solvents. We also demonstrate that these CNF can be chemically functionalized to express biological moieties through available free hydroxyl groups in agarose. We corroborate that agarose CNF are not only conductive and nontoxic, but their functionalization can facilitate cell attachment and response both in vitro and in vivo. Our findings suggest that agarose/CNT hybrid materials are excellent candidates for applications involving neural tissue engineering and biointerfacing with the nervous system. PMID:21887125

  5. Morphological control of polypyrrole coatings electropolymerized onto carbon fibers

    SciTech Connect

    Wood, G.A.; Iroh, J.O.

    1995-12-31

    Polypyrrole coatings have been electropolymerized onto carbon fiber bundles. Several process parameters were varied, and their effect on the morphology and composition of the coatings was studied. The parameters that were varied included the choice of supporting electrolyte, the concentration of electrolyte, the concentration of pyrrole monomer, the applied constant voltage, and time. SEM micrographs of the coated samples revealed at least four distinct morphologies. EDAX analysis, elemental analysis, and infrared spectroscopy all confirmed that part of the supporting electrolyte was present in the coatings. In addition, the parametric variation showed that the type and concentration of the supporting electrolyte had the greatest influence on the resulting morphologies of the coatings. Later, mechanical properties will be examined.

  6. RADIATION EFFECTS ON EPOXY/CARBON-FIBER COMPOSITE

    SciTech Connect

    Hoffman, E

    2008-01-11

    Piping in the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS) must withstand the stresses involved during an unlikely but potential deflagration event. One method proposed for protection and reinforcement of piping during such an event is the use of a carbon fiber-reinforced epoxy composite (Diamond-Wrap{reg_sign}). In the DWPF, this reinforcement composite product would be required to maintain its safety function for a 20-year service life. This product has been ASME-approved (nuclear code case 589) for post-construction maintenance and is DOT-compliant per 49CFR 192 and 195. However, its radiation resistance properties have not been evaluated. This report documents initial radiation resistance testing of the product and microstructural effects. Additional testing is recommended to evaluate radiation effects on specific properties such as burst strength, chemical resistance/weeping and for service life prediction in critical applications.

  7. Effects of Temperature, Oxidation and Fiber Preforms on Fatigue Life of Carbon Fiber-Reinforced Ceramic-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2016-08-01

    In this paper, the effects of temperature, oxidation and fiber preforms on the fatigue life of carbon fiber-reinforced silicon carbide ceramic-matrix composites (C/SiC CMCs) have been investigated. An effective coefficient of the fiber volume fraction along the loading direction (ECFL) was introduced to describe the fiber architecture of preforms. Under cyclic fatigue loading, the fibers broken fraction was determined by combining the interface wear model and fibers statistical failure model at room temperature, and interface/fibers oxidation model, interface wear model and fibers statistical failure model at elevated temperatures in the oxidative environments. When the broken fibers fraction approaches to the critical value, the composites fatigue fracture. The fatigue life S-N curves and fatigue limits of unidirectional, cross-ply, 2D, 2.5D and 3D C/SiC composites at room temperature, 800 °C in air, 1100, 1300 and 1500 °C in vacuum conditions have been predicted.

  8. Edge Delamination and Residual Properties of Drilled Carbon Fiber Composites with and without Short-Aramid-Fiber Interleaf

    NASA Astrophysics Data System (ADS)

    Sun, Zhi; Hu, Xiaozhi; Shi, Shanshan; Guo, Xu; Zhang, Yupeng; Chen, Haoran

    2016-10-01

    Edge delamination is frequently observed in carbon fiber reinforced plastic (CFRP) laminates after machining, due to the low fracture toughness of the resin interfaces between carbon fiber plies. In this study, the effects of incorporating tough aramid fibers into the brittle CFRP system are quantified by measuring the residual properties of bolted CFRP. By adding short-aramid-fiber interleaves in CFRP laminates, the residual tensile strength have been substantially increased by 14 % for twill-weave laminates and 45 % for unidirectional laminates respectively. Moreover, tensile failure was observed as the major mode of toughened laminates, in contrast to shear failure of plain laminates. The qualitative FEM results agreed well with the experimental results that edge delamination would cause relatively higher shear stress and therefore alter the failure mode from tensile failure to shear failure.

  9. Edge Delamination and Residual Properties of Drilled Carbon Fiber Composites with and without Short-Aramid-Fiber Interleaf

    NASA Astrophysics Data System (ADS)

    Sun, Zhi; Hu, Xiaozhi; Shi, Shanshan; Guo, Xu; Zhang, Yupeng; Chen, Haoran

    2016-05-01

    Edge delamination is frequently observed in carbon fiber reinforced plastic (CFRP) laminates after machining, due to the low fracture toughness of the resin interfaces between carbon fiber plies. In this study, the effects of incorporating tough aramid fibers into the brittle CFRP system are quantified by measuring the residual properties of bolted CFRP. By adding short-aramid-fiber interleaves in CFRP laminates, the residual tensile strength have been substantially increased by 14 % for twill-weave laminates and 45 % for unidirectional laminates respectively. Moreover, tensile failure was observed as the major mode of toughened laminates, in contrast to shear failure of plain laminates. The qualitative FEM results agreed well with the experimental results that edge delamination would cause relatively higher shear stress and therefore alter the failure mode from tensile failure to shear failure.

  10. Carbon fiber technique for the investigation of single-cell mechanics in intact cardiac myocytes.

    PubMed

    Sugiura, Seiryo; Nishimura, Satoshi; Yasuda, Soichiro; Hosoya, Yumiko; Katoh, Kaoru

    2006-01-01

    This protocol describes a method for attaching single isolated cardiac myocytes to carbon fibers for mechanical manipulation and measurement. This method relies on cell-adhesive carbon fibers that attach easily to the cell membrane without causing damage, and is thus applicable to intact myocytes. To connect the carbon fiber to micromanipulators, a fiber holder with glass capillaries must first be fabricated. After connection of the fibers to the micromanipulators, firm attachment is easily established by gently pressing the fiber tip onto the cell membrane. Unlike other methods, this technique does not require vast technical expertise, and therefore greatly facilitates experiments. This method enables detection of the effect of drugs, genetic defects or the expression of exogenous proteins on both active and passive properties of cardiac myocytes. In combination with other experimental procedures, this technique can also be applied to the study of mechano-transduction. This protocol can be completed in 3.5 h.

  11. Effect of polyimide interphase on impact and fatigue properties of PEEK/carbon fiber composites

    SciTech Connect

    Davis, R.M.; Gardner, S.H.; Gonzalez, A.

    1995-12-01

    There is a growing interest in carbon fiber reinforced thermoplastic composites. Aqueous suspension prepregging is a new prepregging technique which provides a method for manufacturing PEEK/carbon fiber composites. This method also allows systematic variance of the properties of the interphase region between the carbon fiber and the bulk matrix. It has been found that this interphase region has a effect on dynamic mechanical properties. Notched fatigue testing and impact testing have been used to illustrate the effect of this interphase region. Notched fatigue testing is sensitive to the strength of the fiber-matrix bond. Through these mechanical tests it has been shown that PEEK composites made with a BisP-BTDA binder have a stronger fiber-matrix bond than a reference composite made from APC-2. PEEK composites made with a LaRC TPI binder also have a stronger fiber-matrix bond than APC-2.

  12. Development and characterization of carbon-bonded carbon fiber insulation for radioisotope space power systems

    SciTech Connect

    Wei, G.C.; Robbins, J.M.

    1985-06-01

    The General-Purpose Heat Source (GPHS), an improved radioisotope heat source, employs a unique thermal insulation material, carbon-bonded carbon fiber (CBCF), to protect the fuel capsule and to help achieve the highest possible specific power. The CBCF insulation is made from chopped rayon fiber about 10 ..mu..m in diameter and 250 ..mu..m long, which is carbonized and bonded with phenolic resin particles. The CBCF shapes, both tubes and plates, are formed in a multiple molding facility by vacuum molding a water slurry of the carbonized chopped-rayon fiber (54 wt %) and phenolic resin (46 wt %). The molded shapes are subsequently dried and cured. Final carbonization of the resin is at 1600/sup 0/C. Machining to close tolerances (+-0.08 mm) is accomplished by conventional tooling and fixturing. The resulting material is an excellent lightweight insulation with a nominal density of 0.2 Mg/m/sup 3/ and a thermal conductivity of 0.24 W(m.K) in vacuum at 2000/sup 0/C. Several attributes that make CBCF superior to other known high-temperature insulation materials for the GPHS application have been identified. It has the excellent attributes of light weight, low thermal conductivity, chemical compatibility, and high-temperature capabilities. The mechanical strength of CBCF insulation is satisfactory for the GPHS application; it has passed vibration tests simulating launch conditions. The basic fabrication technique was refined to eliminate undesirable large pores and cracks often present in materials fabricated by earlier techniques. Also, processing was scaled up to incease the fabrication rate by a factor of 10. The specific properties of the CBCF were tailored by adjusting material and processing variables to obtain the desired results. We report here how work on CBCF characterization and development conducted at ORNL from 1978 through 1980 has contributed to the GPHS program to meet the requirements of both the Galileo and Ulysees Missions.

  13. Dipolar resonances in conductive carbon micro-fibers probed by near-field terahertz spectroscopy

    SciTech Connect

    Khromova, I.; Navarro-Cia, M.; Brener, I.; Reno, J. L.; Ponomarev, A.; Mitrofanov, O.

    2015-07-13

    In this study, we observe dipole resonances in thin conductive carbon micro-fibers by detecting an enhanced electric field in the near-field of a single fiber at terahertz (THz) frequencies. Time-domain analysis of the electric field shows that each fiber sustains resonant current oscillations at the frequency defined by the fiber's length. Strong dependence of the observed resonance frequency and degree of field enhancement on the fibers' conductive properties enable direct non-contact probing of the THz conductivity in single carbon micro-fibers. We find the conductivity of the fibers to be within the range of 1– 5∙104 S/m. This approach is suitable for experimental characterization of individual doped semiconductor resonators for THz metamaterials and devices.

  14. Dipolar resonances in conductive carbon micro-fibers probed by near-field terahertz spectroscopy

    DOE PAGES

    Khromova, I.; Navarro-Cia, M.; Brener, I.; Reno, J. L.; Ponomarev, A.; Mitrofanov, O.

    2015-07-13

    In this study, we observe dipole resonances in thin conductive carbon micro-fibers by detecting an enhanced electric field in the near-field of a single fiber at terahertz (THz) frequencies. Time-domain analysis of the electric field shows that each fiber sustains resonant current oscillations at the frequency defined by the fiber's length. Strong dependence of the observed resonance frequency and degree of field enhancement on the fibers' conductive properties enable direct non-contact probing of the THz conductivity in single carbon micro-fibers. We find the conductivity of the fibers to be within the range of 1– 5∙104 S/m. This approach is suitablemore » for experimental characterization of individual doped semiconductor resonators for THz metamaterials and devices.« less

  15. Process modifications for improved carbon fiber composites: Alleviation of the electrical hazards problem

    NASA Technical Reports Server (NTRS)

    Ramohalli, K.

    1980-01-01

    Attempts to alleviate carbon-fiber-composite electrical hazards during airplane crash fires through fiber gasification are described. Thermogravimetric and differential scanning calorimetric experiments found several catalysts that caused fibers to combust when composites were exposed to test fires. Composites were tested in the 'Burn-Bang' apparatus and in high voltage electrical detection grid apparatus. In a standard three minute burn test modified composites released no fibers, while state-of-the-art composites released several hundred fiber fragments. Expected service life with and without catalytic modification was studied and electron microscopy and X-ray microanalysis furnished physical appearance and chemical composition data. An acrylic acid polymer fiber coating was developed that wet the carbon fiber surface uniformly with the catalyst, providing a marked contrast with the uneven coats obtained by solution-dipping.

  16. Mechanical Properties, Surface Structure, and Morphology of Carbon Fibers Pre-heated for Liquid Aluminum Infiltration

    NASA Astrophysics Data System (ADS)

    Kachold, Franziska S.; Kozera, Rafal; Singer, Robert F.; Boczkowska, Anna

    2016-04-01

    To efficiently produce carbon fiber-reinforced aluminum on a large scale, we developed a special high-pressure die casting process. Pre-heating of the fibers is crucial for successful infiltration. In this paper, the influence of heating carried out in industrial conditions on the mechanical properties of the fibers was investigated. Therefore, polyacrylonitrile-based high-tensile carbon fiber textiles were heated by infrared emitters in an argon-rich atmosphere to temperatures between 450 and 1400 °C. Single fiber tensile tests revealed a decrease in tensile strength and strain at fracture. Young's modulus was not affected. Scanning electron microscopy identified cavities on the fiber surface as the reason for the decrease in mechanical properties. They were caused by the attack of atmospheric oxygen. The atomic structure of the fibers did not change at any temperature, as x-ray diffraction confirmed. Based on these data, the pre-heating for the casting process can be optimized.

  17. UV-cured adhesives for carbon fiber composite applications

    NASA Astrophysics Data System (ADS)

    Lu, Hsiao-Chun

    Carbon fiber composite materials are increasingly used in automobile, marine, and aerospace industries due to their unique properties, including high strength, high stiffness and low weight. However, due to their brittle characteristic, these structures are prone to physical damage, such as a bird strike or impact damage. Once the structure is damaged, it is important to have fast and reliable temporary repair until the permanent repair or replacement can take place. In this dissertation, UV-based adhesives were used to provide a bonding strength for temporary repair. Adhesively bonded patch repair is an efficient and effective method for temporary repair. In this study, precured patches (hard patches) and dry fabric patches with laminating resins (soft patches) were performed. UV-based epoxy adhesives were applied to both patch repair systems. For precured patch repair, the bonding strengths were investigated under different surface treatments for bonding area and different adhesives thicknesses. The shear stresses of different UV exposure times and curing times were tested. Besides, the large patch repair was investigated as well. For soft patch repair, the hand wet lay-up was applied due to high viscosity of UV resins. A modified single lap shear testing (ASTM D5868) was applied to determine the shear stress. The large patches used fiber glass instead of carbon fiber to prove the possibility of repair with UV epoxy resin by hand wet lay-up process. The hand lay-up procedure was applied and assisted by vacuum pressure to eliminate the air bubbles and consolidate the patches. To enhance the bonding strength and effective soft patch repair, vacuum assisted resin transferring molding (VaRTM) is the better option. However, only low viscosity resins can be operated by VaRTM. Hence, new UV-based adhesives were formulated. The new UV-based adhesives included photoinitiator (PI), epoxy and different solvents. Solvents were used to compound the photoinitiator into epoxy

  18. Use of nondestructive inspection and fiber optic sensing for damage characterization in carbon fiber fuselage structure

    NASA Astrophysics Data System (ADS)

    Neidigk, Stephen; Le, Jacqui; Roach, Dennis; Duvall, Randy; Rice, Tom

    2014-04-01

    To investigate a variety of nondestructive inspection technologies and assess impact damage characteristics in carbon fiber aircraft structure, the FAA Airworthiness Assurance Center, operated by Sandia National Labs, fabricated and impact tested two full-scale composite fuselage sections. The panels are representative of structure seen on advanced composite transport category aircraft and measured approximately 56"x76". The structural components consisted of a 16 ply skin, co-cured hat-section stringers, fastened shear ties and frames. The material used to fabricate the panels was T800 unidirectional pre-preg (BMS 8-276) and was processed in an autoclave. Simulated hail impact testing was conducted on the panels using a high velocity gas gun with 2.4" diameter ice balls in collaboration with the University of California San Diego (UCSD). Damage was mapped onto the surface of the panels using conventional, hand deployed ultrasonic inspection techniques, as well as more advanced ultrasonic and resonance scanning techniques. In addition to the simulated hail impact testing performed on the panels, 2" diameter steel tip impacts were used to produce representative impact damage which can occur during ground maintenance operations. The extent of impact damage ranges from less than 1 in2 to 55 in2 of interply delamination in the 16 ply skin. Substructure damage on the panels includes shear tie cracking and stringer flange disbonding. It was demonstrated that the fiber optic distributed strain sensing system is capable of detecting impact damage when bonded to the backside of the fuselage.

  19. Carbon fiber CVD coating by carbon nanostructured for space materials protection against atomic oxygen

    NASA Astrophysics Data System (ADS)

    Pastore, Roberto; Bueno Morles, Ramon; Micheli, Davide

    2016-07-01

    adhesion and durability in the environment. Though these coatings are efficient in protecting polymer composites, their application imposes severe constraints. Their thermal expansion coefficients may differ markedly from those of polymer composite substrates: as a result, cracks develop in the coatings on thermal cycling and AO can penetrate through them to the substrate. In addition to the technicalities of forming an effective barrier, such factors as cost, convenience of application and ease of repair are important considerations in the selection of a coating for a particular application. The latter issues drive the aerospace research toward the development of novel light composite materials, like the so called polymer nanocomposites, which are materials with a polymer matrix and a filler with at least one dimension less than 100 nanometers. Current interest in nanocomposites has been generated and maintained because nanoparticle-filled polymers exhibit unique combinations of properties not achievable with traditional composites. These combinations of properties can be achieved because of the small size of the fillers, the large surface area the fillers provide, and in many cases the unique properties of the fillers themselves. In particular, the carbon fiber-based polymeric composite materials are the basic point of interest: the aim of the present study is to find new solution to produce carbon fiber-based composites with even more upgraded performances. One intriguing strategy to tackle such an issue has been picked out in the coupling between the carbon fibers and the carbon nanostructures. That for two main reasons: first, carbon nanostructures have shown fancy potentialities for any kind of technological applications since their discovery, second, the chemical affinity between fiber and nanostructure (made of the same element) should be a likely route to approach the typical problems due to thermo-mechanical compatibility. This work is joined in such framework

  20. Mechanical Properties of Carbon Fiber-Reinforced Aluminum Manufactured by High-Pressure Die Casting

    NASA Astrophysics Data System (ADS)

    Kachold, Franziska; Singer, Robert

    2016-08-01

    Carbon fiber reinforced aluminum was produced by a specially adapted high-pressure die casting process. The MMC has a fiber volume fraction of 27%. Complete infiltration was achieved by preheating the bidirectional, PAN-based carbon fiber body with IR-emitters to temperatures of around 750 °C. The degradation of the fibers, due to attack of atmospheric oxygen at temperatures above 600 °C, was limited by heating them in argon-rich atmosphere. Additionally, the optimization of heating time and temperature prevented fiber degradation. Only the strength of the outer fibers is reduced by 40% at the most. The fibers in core of fiber body are nearly undamaged. In spite of successful manufacturing, the tensile strength of the MMC is below strength of the matrix material. Also unidirectional MMCs with a fiber volume fraction of 8% produced under the same conditions, lack of the reinforcing effect. Two main reasons for the unsatisfactory mechanical properties were identified: First, the fiber-free matrix, which covers the reinforced core, prevents effective load transfer from the matrix to the fibers. And second, the residual stresses in the fiber-free zones are as high as 100 MPa. This causes premature failure in the matrix. From this, it follows that the local reinforcement of an actual part is limited. The stress distribution caused by residual stresses and by loading needs to be known. In this way, the reinforcing phase can be placed and aligned accordingly. Otherwise delamination and premature failure might occur.

  1. New generation fiber reinforced polymer composites incorporating carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Soliman, Eslam

    The last five decades observed an increasing use of fiber reinforced polymer (FRP) composites as alternative construction materials for aerospace and infrastructure. The high specific strength of FRP attracted its use as non-corrosive reinforcement. However, FRP materials were characterized with a relatively low ductility and low shear strength compared with steel reinforcement. On the other hand, carbon nanotubes (CNTs) have been introduced in the last decade as a material with minimal defect that is capable of increasing the mechanical properties of polymer matrices. This dissertation reports experimental investigations on the use of multi-walled carbon nanotubes (MWCNTs) to produce a new generation of FRP composites. The experiments showed significant improvements in the flexure properties of the nanocomposite when functionalized MWCNTs were used. In addition, MWCNTs were used to produce FRP composites in order to examine static, dynamic, and creep behavior. The MWCNTs improved the off-axis tension, off-axis flexure, FRP lap shear joint responses. In addition, they reduced the creep of FRP-concrete interface, enhanced the fracture toughness, and altered the impact resistance significantly. In general, the MWCNTs are found to affect the behaviour of the FRP composites when matrix failure dominates the behaviour. The improvement in the mechanical response with the addition of low contents of MWCNTs would benefit many industrial and military applications such as strengthening structures using FRP composites, composite pipelines, aircrafts, and armoured vehicles.

  2. Mechanical properties of carbon fiber composites for applications in space

    NASA Astrophysics Data System (ADS)

    Hana, P.; Inneman, A.; Daniel, V.; Sieger, L.; Petru, M.

    2015-01-01

    This article describes method of measurement mechanical properties of carbon fiber composites in space. New material structures are specifically designed for use on space satellites. Composite structures will be exposed to cosmic radiation in Earth orbit on board of a '2U CubeSat' satellite. Piezoelectric ceramic sensors are used for detection mechanical vibrations of composite test strip. A great deal of attention is paid to signal processing using 8-bit microcontroler. Fast Fourier Transformation is used. Fundamental harmonic frequencies and damping from on-board measurements will serve as the input data for terrestrial data processing. The other step of elaboration data is creation of the physical model for evaluating mechanical properties of Carbon composite - Piezoelectric ceramic system. Evaluation of anisotropic mechanical properties of piezoelectric ceramics is an interesting secondary outcome of the investigation. Extreme changes in temperature and the effect of cosmic rays will affect the mechanical properties and durability of the material used for the external construction of satellites. Comparative terrestrial measurements will be performed.

  3. Supercapacitance from Cellulose and Carbon Nanotube Nanocomposite Fibers

    PubMed Central

    2013-01-01

    Multiwalled carbon nanotube (MWNT)/cellulose composite nanofibers have been prepared by electrospinning a MWNT/cellulose acetate blend solution followed by deacetylation. These composite nanofibers were then used as precursors for carbon nanofibers (CNFs). The effect of nanotubes on the stabilization of the precursor and microstructure of the resultant CNFs were investigated using thermogravimetric analysis, transmission electron microscopy and Raman spectroscopy. It is demonstrated that the incorporated MWNTs reduce the activation energy of the oxidative stabilization of cellulose nanofibers from ∼230 to ∼180 kJ mol–1. They also increase the crystallite size, structural order, and electrical conductivity of the activated CNFs (ACNFs). The surface area of the ACNFs increased upon addition of nanotubes which protrude from the fiber leading to a rougher surface. The ACNFs were used as the electrodes of a supercapacitor. The electrochemical capacitance of the ACNF derived from pure cellulose nanofibers is demonstrated to be 105 F g–1 at a current density of 10 A g–1, which increases to 145 F g–1 upon the addition of 6% of MWNTs. PMID:24070254

  4. Interfacial Microstructure and Enhanced Mechanical Properties of Carbon Fiber Composites Caused by Growing Generation 1-4 Dendritic Poly(amidoamine) on a Fiber Surface.

    PubMed

    Gao, Bo; Zhang, Ruliang; Gao, Fucheng; He, Maoshuai; Wang, Chengguo; Liu, Lei; Zhao, Lifen; Cui, Hongzhi

    2016-08-23

    In an attempt to improve the mechanical properties of carbon fiber composites, propagation of poly(amidoamine) (PAMAM) dendrimers by in situ polymerization on a carbon fiber surface was performed. During polymerization processes, PAMAM was grafted on carbon fiber by repeated Michael addition and amidation reactions. The changes in surface microstructure and the chemical composition of carbon fibers before and after modification were investigated by atomic force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. All the results indicated that PAMAM was successfully grown on the carbon fiber surface. Such propagation could significantly increase the surface roughness and introduce sufficient polar groups onto the carbon fiber surface, enhancing the surface wettability of carbon fiber. The fractured surface of carbon fiber-reinforced composites showed a great enhancement of interfacial adhesion. Compared with those of desized fiber composites, the interlaminar shear strength and interfacial shear strength of PAMAM/fiber-reinforced composites showed increases of 55.49 and 110.94%, respectively. PMID:27472250

  5. Carbon fiber-reinforced composites: Applications in alternative energy & transportation systems

    SciTech Connect

    Dry, A.; Betts, J.; Strandburg, D.

    1996-12-31

    Historically, carbon fiber-reinforced composites (CFRCs) were limited to aerospace applications, primarily due to the high cost of the staple carbon fiber strands and labor-intensive composite manufacturing. By the early 1990s, new cost-effective fabrication methods reduced the price of carbon fiber tenfold from the initial level of over $100.00/lb. to around $12.00/lb. As a result, entirely new markets for CFRCs emerged to take advantage of the unbeatable strength/weight properties, primarily in the sporting goods industry. Today`s market is much more varied, with applications appearing in infrastructure, industrial and mechanical components, and alternative energy and transportation systems. In fact, carbon fiber-reinforced composites are enabling the technologies for the myriad of new alternative energy and transportation systems in development. Compressed natural gas (CNG) and liquid natural gas (LNG) tanks are filament wound from carbon fiber, which provides the lightweight/high strength construction necessary for efficient energy storage. Similarly, carbon fiber flywheels allow higher rotor speeds for greater energy storage capability. Lightweight carbon fiber-reinforced windmill blades, are in development with longer chord lengths for greater energy capture. In summary, CFRCs are being evaluated for structural components in practically all alternative fuel and transportation sectors, including automotive, due to the increased energy efficiency allowed by the overall weight reduction. As new programs to further develop these high volume applications emerge, the carbon fiber industry will be challenged to reduce the cost of carbon fiber and composite manufacturing methods to ensure continued market expansion.

  6. Growth, structure, and optical properties of carbon-reinforced silica fibers

    SciTech Connect

    Zhang, Z. J.; Ajayan, P. M.; Ramanath, G.; Vacik, J.; Xu, Y. H.

    2001-06-11

    We report the synthesis of carbon-reinforced silica fibers by methane exposure of metallocene-treated oxidized-Si(001) substrates at 1100{degree}C. The SiO{sub 2} cap layer transforms into silica fibers reinforced by glassy carbon in the core during methane exposure. High-resolution electron microscopy and spatially resolved spectroscopy measurements of the fibers reveal an amorphous structure without a hollow, and domains of glassy carbon embedded at the fiber core. The carbon-reinforced fibers are optically transparent and have an optical band gap of {approx_equal}3.1 eV. These fibers are organized in radial patterns that vary for different metallocene species. On nickelocene-treated substrates, the fibers originate from the circumference of the circular templates and grow outwards, forming radial patterns. On ferrocene-treated substrates, randomly oriented fibers grow within as well as slightly outside the perimeter of the templates, forming wreath-like patterns. Aligned growth of such fibers could be useful for fabricating optoelectronics devices and reinforced composites. {copyright} 2001 American Institute of Physics.

  7. Effect of interfacial chemical bonding and surface topography on adhesion in carbon fiber/epoxy composites

    SciTech Connect

    Drzal, L.T.; Sugiura, N.; Hook, D. |

    1994-12-31

    A series of PAN-based IM6 carbon fibers having varying amounts of surface treatment were, pretreated with compounds representing the constituents encountered in epoxy composites to pre-react any groups on the fiber surface before composite fabrication in order to determine the effect of chemical bonding on fiber-matrix adhesion. Chemical bonding was quantified using XPS. Chemical bonding between reactive groups in amine cured epoxy matrices and the surface groups present on IN46 carbon fibers as a result of commercial surface treatments has been detected although the absolute amount of chemical bonding is low (1-3%). It was found that reaction with monofunctional epoxy groups having hydrocarbon functionalities blocked the surface from further reaction and reduced the adhesion that could be attained to its lowest value. Prereaction with difunctional amines had little effect on adhesion when compared to normal composite fabrication procedures. Prereaction with difunctional epoxy groups did enhance adhesion levels over the level attained in normal composite fabrication methods. These results showed that chemical bonding between epoxy and the carbon fiber surface could increases the adhesion between fiber and matrix about 25% while between the amino group and the carbon fiber surface about 15%. Quantitative measurements of the fiber surface microtopography were made with scanning tunneling microscopy. An increase in roughness was detected with increasing surface treatment. It was concluded that surface roughness also accounted for a significant increase in fiber-matrix adhesion.

  8. Preparation and characterization of porous carbon material-coated solid-phase microextraction metal fibers.

    PubMed

    Zhu, Fang; Guo, Jiaming; Zeng, Feng; Fu, Ruowen; Wu, Dingcai; Luan, Tiangang; Tong, Yexiang; Lu, Tongbu; Ouyang, Gangfeng

    2010-12-10

    Two kinds of porous carbon materials, including carbon aerogels (CAs), wormhole-like mesoporous carbons (WMCs), were synthesized and used as the coatings of solid-phase microextraction (SPME) fibers. By using stainless steel wire as the supporting core, six types of fibers were prepared with sol-gel method, direct coating method and direct coating plus sol-gel method. Headspace SPME experiments indicated that the extraction efficiencies of the CA fibers are better than those of the WMC fibers, although the surface area of WMCs is much higher than that of CAs. The sol-gel-CA fiber (CA-A) exhibited excellent extraction properties for non-polar compounds (BTEX, benzene, toluene, ethylbenzene, o-xylene), while direct-coated CA fiber (CA-B) presented the best performance in extracting polar compounds (phenols). The two CA fibers showed wide linear ranges, low detection limits (0.008-0.047μgL(-1) for BTEX, 0.15-5.7μgL(-1) for phenols) and good repeatabilities (RSDs less than 4.6% for BTEX, and less than 9.5% for phenols) and satisfying reproducibilities between fibers (RSDs less than 5.2% for BTEX, and less than 9.9% for phenols). These fibers were successfully used for the analysis of water samples from the Pearl River, which demonstrated the applicability of the home-made CA fibers. PMID:21074162

  9. Preparation and characterization of porous carbon material-coated solid-phase microextraction metal fibers.

    PubMed

    Zhu, Fang; Guo, Jiaming; Zeng, Feng; Fu, Ruowen; Wu, Dingcai; Luan, Tiangang; Tong, Yexiang; Lu, Tongbu; Ouyang, Gangfeng

    2010-12-10

    Two kinds of porous carbon materials, including carbon aerogels (CAs), wormhole-like mesoporous carbons (WMCs), were synthesized and used as the coatings of solid-phase microextraction (SPME) fibers. By using stainless steel wire as the supporting core, six types of fibers were prepared with sol-gel method, direct coating method and direct coating plus sol-gel method. Headspace SPME experiments indicated that the extraction efficiencies of the CA fibers are better than those of the WMC fibers, although the surface area of WMCs is much higher than that of CAs. The sol-gel-CA fiber (CA-A) exhibited excellent extraction properties for non-polar compounds (BTEX, benzene, toluene, ethylbenzene, o-xylene), while direct-coated CA fiber (CA-B) presented the best performance in extracting polar compounds (phenols). The two CA fibers showed wide linear ranges, low detection limits (0.008-0.047μgL(-1) for BTEX, 0.15-5.7μgL(-1) for phenols) and good repeatabilities (RSDs less than 4.6% for BTEX, and less than 9.5% for phenols) and satisfying reproducibilities between fibers (RSDs less than 5.2% for BTEX, and less than 9.9% for phenols). These fibers were successfully used for the analysis of water samples from the Pearl River, which demonstrated the applicability of the home-made CA fibers.

  10. Investigation of Structural Properties of Carbon-Epoxy Composites Using Fiber-Bragg Gratings

    NASA Technical Reports Server (NTRS)

    Grant, J.; Kaul, R.; Taylor, S.; Jackson, K.; Sharma, A.; Burdine, Robert V. (Technical Monitor)

    2002-01-01

    Fiber Bragg-gratings are embedded in carbon-epoxy laminates as well as bonded on the surface of cylindrical structures fabricated out of such composites. Structural properties of such composites is investigated. The measurements include stress-strain relation in laminates and Poisson's ratio in several specimens with varying orientation of the optical fiber Bragg-sensor with respect to the carbon fiber in an epoxy matrix. Additionally, Bragg gratings are bonded on the surface of cylinders fabricated out of carbon-epoxy composites and longitudinal and hoop strain on the surface is measured.

  11. As assessment of power system vulnerability to release of carbon fibers during commercial aviation accidents

    NASA Technical Reports Server (NTRS)

    Larocque, G. R.

    1980-01-01

    The vulnerability of a power distribution system in Bedford and Lexington, Massachusetts to power outages as a result of exposure to carbon fibers released in a commercial aviation accident in 1993 was examined. Possible crash scenarios at Logan Airport based on current operational data and estimated carbon fiber usage levels were used to predict exposure levels and occurrence probabilities. The analysis predicts a mean time between carbon fiber induced power outages of 2300 years with an expected annual consequence of 0.7 persons losing power. In comparison to historical outage data for the system, this represents a 0.007% increase in outage rate and 0.07% increase in consequence.

  12. Properties of Multifunctional Hybrid Carbon Nanotube/Carbon Fiber Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Cano, Roberto J.; Kang, Jin Ho; Grimsley, Brian W.; Ratcliffe, James G.; Siochi, Emilie J.

    2016-01-01

    For aircraft primary structures, carbon fiber reinforced polymer (CFRP) composites possess many advantages over conventional aluminum alloys due to their light weight, higher strength- and stiffness-to-weight ratios, and low life-cycle maintenance costs. However, the relatively low electrical and thermal conductivities of CFRP composites fail to provide structural safety in certain operational conditions such as lightning strikes. Carbon nanotubes (CNT) offer the potential to enhance the multi-functionality of composites with improved thermal and electrical conductivity. In this study, hybrid CNT/carbon fiber (CF) polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel® IM7/8852 prepreg. Resin concentrations from 1 wt% to 50 wt% were used to infuse the CNT sheets prior to composite fabrication. The interlaminar properties of the resulting hybrid composites were characterized by mode I and II fracture toughness testing. Fractographical analysis was performed to study the effect of resin concentration. In addition, multi-directional physical properties like thermal conductivity of the orthotropic hybrid polymer composite were evaluated.

  13. Carbon-bonded carbon fiber insulation for radioisotope space power systems

    SciTech Connect

    Wei, G.C.; Robbins, J.M.

    1985-05-01

    A carbon-bonded carbon fiber (CBCF) insulation developed for a radioisotope heat source is made from chopped rayon fiber about 10 ..mu..m in diameter and 250 ..mu..m long, which is carbonized and bonded with phenolic resin particles. The CBCF is an excellent lightweight insulating material with a nominal density of 0.2 Mg/m/sup 3/ and a thermal conductivity of 0.24 W/(m-K) in vacuum at 2000/sup 0/C. Several attributes that make CBCF particularly suitable for the heat source application have been identified. These include light weight, low thermal conductivity, chemical compatibility, and high-temperature capabilities. The mechanical strength of CBCF insulation is satisfactory for the application. The basic fabrication technique was refined to eliminate undesirable large pores and cracks often present in materials fabricated by earlier techniques. Also, processing was scaled up to increase the fabrication rate by a factor of 10. The specific properties of the CBCF were tailored by adjusting material and processing variables to obtain the desired results. 22 references, 13 figures, 4 tables.

  14. Carbon-bonded carbon fiber insulation for radioisotope space power systems

    SciTech Connect

    Wei, G C; Robbins, J M

    1985-05-01

    A carbon-bonded carbon fiber (CBCF) insulation developed for a radioisotope heat source is made from chopped rayon fiber about 10..mu..m long, which is carbonized and bonded with phenolic resin particles. The CBCF is an excellent lightweight insulating material with a nominal density of 0.2 Mg/m/sup 3/ and a thermal conductivity of 0.24 W/(m-K) in vacuum at 2000/sup 0/C. (Several attributes that make CBCF particularly suitable for the heat source application have been identified.) These include light weight, low thermal conductivity, chemical compatibility, and hightemperature capabilities. The mechanical strength of CBCF insulation is satisfactory for the application. The basic fabrication technique was refined to eliminate undesirable large pores and cracks often present in materials fabricated by earlier techniques. Also, processing was scaled up to increase the fabrication rate by a factor of 10. The specific properties of the CBCF were tailored by adjusting material and processing variables to obtain the desired results.

  15. Dry Process for Making Polyimide/ Carbon-and-Boron-Fiber Tape

    NASA Technical Reports Server (NTRS)

    Belvin, Harry L.; Cano, Roberto J.; Johnston, Norman J.; Marchello, Joseph M.

    2003-01-01

    A dry process has been invented as an improved means of manufacturing composite prepreg tapes that consist of high-temperature thermoplastic polyimide resin matrices reinforced with carbon and boron fibers. Such tapes are used (especially in the aircraft industry) to fabricate strong, lightweight composite-material structural components. The inclusion of boron fibers results in compression strengths greater than can be achieved by use of carbon fibers alone. The present dry process is intended to enable the manufacture of prepreg tapes (1) that contain little or no solvent; (2) that have the desired dimensions, fiber areal weight, and resin content; and (3) in which all of the fibers are adequately wetted by resin and the boron fibers are fully encapsulated and evenly dispersed. Prepreg tapes must have these properties to be useable in the manufacture of high-quality composites by automated tape placement. The elimination of solvent and the use of automated tape placement would reduce the overall costs of manufacturing.

  16. Tensile strength and its scatter of unidirectional carbon fiber reinforced composites

    SciTech Connect

    Hamada, H.; Oya, N.; Yamashita, K.; Maekawa, Z.I.

    1995-12-31

    0 (along the fiber direction) and 90 degree (transverse to the fiber direction) tension tests of Carbon Fiber Reinforced Plastics (CFRP) using a great number of specimens were conducted. Tensile properties and their scatter were evaluated by means of the data base. Materials used in this study were seven kinds of carbon fibers and three kinds of epoxy resins. Reinforcing fiber and matrix resin properties strongly affected on 0 and 90 degree properties of CFRP respectively. In 0 degree tension tests, fracture mode of specimen vaned in each material, and a relationship between the scatter of strength and the fracture mode existed. From the results of 9 degree tension tests, some differences of interfacial properties between each laminate were` also detected. According to some considerations on fracture mechanism in 0 degree tension test, it was deduced that the fracture mode depended on the balance of fiber, matrix and interface properties.

  17. Rate dependent response and failure of a ductile epoxy and carbon fiber reinforced epoxy composite

    SciTech Connect

    Brown, Eric N; Rae, Philip J; Dattelbaum, Dana M; Stahl, David B

    2010-01-01

    An extensive characterization suite has been performed on the response and failure of a ductile epoxy 55A and uniaxial carbon fiber reinforced epoxy composite of IM7 fibers in 55A resin from the quasistatic to shock regime. The quasistatic and intermediate strain rate response, including elastic modulus, yield and failure have are characterized by quasistatic, SHPB, and DMA measurements as a function of fiber orientation and temperature. The high strain rate shock effect of fiber orientation in the composite and response of the pure resin are presented for plate impact experiments. It has previously been shown that at lower impact velocities the shock velocity is strongly dependent on fiber orientation but at higher impact velocity the in-plane and through thickness Hugoniots converge. The current results are compared with previous studies of the shock response of carbon fiber composites with more conventional brittle epoxy matrices. The spall response of the composite is measured and compared with quasistatic fracture toughness measurements.

  18. Interlaminar improvement of carbon fiber/epoxy composites via depositing mixture of carbon nanotubes and sizing agent

    NASA Astrophysics Data System (ADS)

    Fang, Cuiqin; Wang, Julin; Zhang, Tao

    2014-12-01

    The effects of deposition to carbon fibers surfaces with mixture of functionalized multi-walled carbon fibers (MWCNTs) and sizing agent were investigated. Relationships between CNTs and sizing agent were studied with Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS) and Ubbelohde viscometer. The results revealed that CNTs could react with sizing agent at 120 °C, and optimal reaction occurs when mass ratio was about 1:20. Then, carbon fibers were immersed in mixed aqueous suspension of CNTs and sizing agent with the above ratio dispersed by ultrasonication. According to scanning electron microscope (SEM) observations, fibers surfaces were coated with CNTs and sizing agent. The static contact angle tests indicated wetting performance between fibers and epoxy resin were improved after deposited procedures. Interlaminar shear strength was increased by 67.01% for fibers/epoxy resin composites after mixture deposited process. Moreover, the tensile strength of single fibers after depositing showed a slightly increase compared with that of fibers without depositing layer.

  19. Carbon aerogel composites prepared by ambient drying and using oxidized polyacrylonitrile fibers as reinforcements.

    PubMed

    Feng, Junzong; Zhang, Changrui; Feng, Jian; Jiang, Yonggang; Zhao, Nan

    2011-12-01

    Carbon fiber-reinforced carbon aerogel composites (C/CAs) for thermal insulators were prepared by copyrolysis of resorcinol-formaldehyde (RF) aerogels reinforced by oxidized polyacrylonitrile (PAN) fiber felts. The RF aerogel composites were obtained by impregnating PAN fiber felts with RF sols, then aging, ethanol exchanging, and drying at ambient pressure. Upon carbonization, the PAN fibers shrink with the RF aerogels, thus reducing the difference of shrinkage rates between the fiber reinforcements and the aerogel matrices, and resulting in C/CAs without any obvious cracks. The three point bend strength of the C/CAs is 7.1 ± 1.7 MPa, and the thermal conductivity is 0.328 W m(-1) K(-1) at 300 °C in air. These composites can be used as high-temperature thermal insulators (in inert atmospheres or vacuum) or supports for phase change materials in thermal protection system.

  20. Determination of pressure drop across activated carbon fiber respirator cartridges.

    PubMed

    Balanay, Jo Anne G; Lungu, Claudiu T

    2016-01-01

    Activated carbon fiber (ACF) is considered as an alternative adsorbent to granular activated carbon (GAC) for the development of thinner, lighter, and efficient respirators because of their larger surface area and adsorption capacities, thinner critical bed depth, lighter weight, and fabric form. This study aims to measure the pressure drop across different types of commercially available ACFs in respirator cartridges to determine the ACF composition and density that will result in acceptably breathable respirators. Seven ACF types in cloth (ACFC) and felt (ACFF) forms were tested. ACFs in cartridges were challenged with pre-conditioned constant air flow (43 LPM, 23°C, 50% RH) at different compositions (single- or combination-ACF type) in a test chamber. Pressure drop across ACF cartridges were obtained using a micromanometer, and compared among different cartridge configurations, to those of the GAC cartridge, and to the NIOSH breathing resistance requirements for respirator cartridges. Single-ACF type cartridges filled with any ACFF had pressure drop measurements (23.71-39.93 mmH2O) within the NIOSH inhalation resistance requirement of 40 mmH2O, while those of the ACFC cartridges (85.47±3.67 mmH2O) exceeded twice the limit due possibly to the denser weaving of ACFC fibers. All single ACFF-type cartridges had higher pressure drop compared to the GAC cartridge (23.13±1.14 mmH2O). Certain ACF combinations (2 ACFF or ACFC/ACFF types) resulted to pressure drop (26.39-32.81 mmH2O) below the NIOSH limit. All single-ACFF type and all combination-ACF type cartridges with acceptable pressure drop had much lower adsorbent weights than GAC (≤15.2% of GAC weight), showing potential for light-weight respirator cartridges. 100% ACFC in cartridges may result to respirators with high breathing resistance and, thus, is not recommended. The more dense ACFF and ACFC types may still be possibly used in respirators by combining them with less dense ACFF materials and/or by

  1. Determination of pressure drop across activated carbon fiber respirator cartridges.

    PubMed

    Balanay, Jo Anne G; Lungu, Claudiu T

    2016-01-01

    Activated carbon fiber (ACF) is considered as an alternative adsorbent to granular activated carbon (GAC) for the development of thinner, lighter, and efficient respirators because of their larger surface area and adsorption capacities, thinner critical bed depth, lighter weight, and fabric form. This study aims to measure the pressure drop across different types of commercially available ACFs in respirator cartridges to determine the ACF composition and density that will result in acceptably breathable respirators. Seven ACF types in cloth (ACFC) and felt (ACFF) forms were tested. ACFs in cartridges were challenged with pre-conditioned constant air flow (43 LPM, 23°C, 50% RH) at different compositions (single- or combination-ACF type) in a test chamber. Pressure drop across ACF cartridges were obtained using a micromanometer, and compared among different cartridge configurations, to those of the GAC cartridge, and to the NIOSH breathing resistance requirements for respirator cartridges. Single-ACF type cartridges filled with any ACFF had pressure drop measurements (23.71-39.93 mmH2O) within the NIOSH inhalation resistance requirement of 40 mmH2O, while those of the ACFC cartridges (85.47±3.67 mmH2O) exceeded twice the limit due possibly to the denser weaving of ACFC fibers. All single ACFF-type cartridges had higher pressure drop compared to the GAC cartridge (23.13±1.14 mmH2O). Certain ACF combinations (2 ACFF or ACFC/ACFF types) resulted to pressure drop (26.39-32.81 mmH2O) below the NIOSH limit. All single-ACFF type and all combination-ACF type cartridges with acceptable pressure drop had much lower adsorbent weights than GAC (≤15.2% of GAC weight), showing potential for light-weight respirator cartridges. 100% ACFC in cartridges may result to respirators with high breathing resistance and, thus, is not recommended. The more dense ACFF and ACFC types may still be possibly used in respirators by combining them with less dense ACFF materials and/or by

  2. The scatter of mechanical values of carbon fiber composites and its causes. [statistical values of strength

    NASA Technical Reports Server (NTRS)

    Roth, S.

    1979-01-01

    The scatter of experimental data obtained in an investigation of the parameters of structural components was investigated. Strength parameters which are determined by the resin or the adhesion between fiber and resin were included. The statistical characteristics of the mechanical parameters of carbon fiber composites, and the possibilities which exist to reduce this scatter were emphasized. It is found that quality control tests of fiber and resin are important for such a reduction.

  3. Activation and Micropore Structure Determination of Activated Carbon-Fiber Composites

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.

    1999-04-23

    Previous work focused on the production of carbon fiber composites and subsequently activating them to induce adsorbent properties. One problem related to this approach is the difficulty of uniformly activating large composites. In order to overcome this problem, composites have been made from pre-activated fibers. The loss of surface area upon forming the composites after activation of the fibers was investigated. The electrical resistivity and strength of these composites were compared to those made by activation after forming. It was found that the surface area is reduced by about 35% by forming the composite from pre-activated fibers. However, the properties of the activated sample are very uniform: the variation in surface area is less than {+-}0.5%. So, although the surface area is somewhat reduced, it is believed that making composites from pre-activated fibers could be useful in applications where the BET surface area is not required to be very high. The strength of the composites produced from pre-activated fibers is lower than for composites activated after forming when the carbon burnoff is below 45%. For higher burnoffs, the strength of composites made with pre-activated fibers is as good or better. In both cases, there is a dramatic decrease in strength when the fiber:binder ratio is reduced below 4:1. The electrical resistivity is slightly higher for composites made from pre-activated fibers than for composites that are activated after forming, other parameters being constant (P-200 fibers, similar carbon burnoffs). For both types of composite the resistivity was also found to increase with carbon burnoff. This is attributed to breakage of the fiber causing shorter conductive paths. The electrical resistivity also increases when the binder content is lowered, which suggests that there are fewer solid contact points between the fibers.

  4. Conductivity and Ambient Stability of Halogen-Doped Carbon Nanotube Fibers

    NASA Technical Reports Server (NTRS)

    Gaier, J. R.; Chirino, C. M.; Chen, M.; Waters, D. L.; Tran, Mai Kim; Headrick, R.; Young, C. C.; Tsentalovich, D.; Whiting, B.; Pasquali, M.; Waarbeek, Ron ter; Otto, Marcin J.

    2014-01-01

    Carbon nanotube fibers were fabricated using a variety of spinning conditions and post-spinning processing with the goal of creating a high-conductivity yet environmentally stable fiber. These fiber variants were then doped with bromine, iodine, iodine chloride, or iodine bromide and their electrical and microstructural properties were characterized. Environmentally stable compounds were synthesized with electrical conductivity greater than 50,000 Scm.

  5. High-resolution Brillouin analysis in a carbon-fiber-composite unmanned aerial vehicle model wing

    NASA Astrophysics Data System (ADS)

    Stern, Yonatan; London, Yosef; Preter, Eyal; Antman, Yair; Shlomi, Orel; Silbiger, Maayan; Adler, Gadi; Zadok, Avi

    2016-05-01

    Standard optical fibers are successfully embedded within a model wing of an unmanned aerial vehicle, constructed of carbon fiber and epoxy, during its production. Time-gated Brillouin optical correlation domain analysis along the embedded optical fibers is performed with a spatial resolution of 4 cm. Tests were carried out using a portable measurement setup prototype. The results represent an important step towards applications of high-resolution Brillouin analysis outside the research laboratory.

  6. Epoxy/carbon composite resins in dentistry: mechanical properties related to fiber reinforcements.

    PubMed

    Viguie, G; Malquarti, G; Vincent, B; Bourgeois, D

    1994-09-01

    Composite carbon/epoxy resin techniques for restorative dentistry have improved with the development of various composite resins classified according to fiber reinforcement, such as short fibers, woven materials, or long unidirectional fibers. This study of the mechanical properties with three-point flexion enabled comparison of the flexural strengths. The modulus of elasticity of different composite resin materials was determined so that the appropriate reinforced composite resin could be selected for specific clinical conditions.

  7. Environmental effects on the hybrid glass fiber/carbon fiber composites

    NASA Astrophysics Data System (ADS)

    Tsai, Yun-I.

    2009-12-01

    Fiber reinforced polymer composites (FRPCs) have been widely used to replace conventional metals due to the high specific strength, fatigue resistance, and light weight. In the power distribution industry, an advanced composites rod has been developed to replace conventional steel cable as the load-bearing core of overhead conductors. Such conductors, called aluminum conductor composite core (ACCC) significantly increases the transmitting efficiency of existing power grid system without extensive rebuilding expenses, while meeting future demand for electricity. In general, the service life of such overhead conductors is required to be at least 30 years. Therefore, the long-term endurance of the composite core in various environments must be well-understood. Accelerated aging by hygrothermal exposure was conducted to determine the effect of moisture on the glass fiber (GF)/carbon fiber (CF) hybrid composites. The influence of water immersion and humid air exposure on mechanical properties is investigated. Results indicated that immersion in water is the most severe environment for such hybrid GF/CF composites, and results in greater saturation and degradation of properties. When immersed directly in water, the hybrid GF/CF composites exhibit a moisture uptake behavior that is more complex than composite materials reinforced with only one type of fiber. The unusual diffusion behavior is attributed to a higher packing density of fibers at the annular GF/CF interface, which acts as a temporary moisture barrier. Moisture uptake leads to the mechanical and thermal degradation of such hybrid GF/CF composites. Findings presented here indicate that the degradation is a function of exposure temperature, time, and moisture uptake level. Results also indicate that such hybrid GF/CF composites recover short beam shear (SBS) strength and glass transition temperature (Tg) values comparable to pre-aged samples after removal of the absorbed moisture. In the hygrothermal environment

  8. Mode-locked fiber/waveguide lasers based on a fiber taper embedded in carbon nanotubes/polymer composite

    NASA Astrophysics Data System (ADS)

    Wang, Qing; Khanh, Kieu; Honkanen, Seppo; Kueppers, Franko

    2008-04-01

    We generated 2 nJ, ~690 fs pulses with 10 MHz repetition rate from a linear cavity mode-locked Er 3+-doped fiber laser with a fiber taper embedded in carbon nanotubes (CNTs)/polymer composite. Evanescent field out of the taper section can interact with CNTs to see saturation of absorption. With the fiber based saturable absorber this laser has simple and robust all-fiber configuration comparing to traditional linear cavity mode-locked lasers with semiconductor saturable absorbers. In addition, we have demonstrated a mode-locked ring laser, with a similar saturable absorber, by using an ion-exchanged Er 3+-Yb 3+-codoped planar waveguide as the gain medium.

  9. Thermal oxidation induced degradation of carbon fiber reinforced composites and carbon nanotube sheet enhanced fiber/matrix interface for high temperature aerospace structural applications

    NASA Astrophysics Data System (ADS)

    Haque, Mohammad Hamidul

    Recent increase in the use of carbon fiber reinforced polymer matrix composite, especially for high temperature applications in aerospace primary and secondary structures along with wind energy and automotive industries, have generated new challenges to predict its failure mechanisms and service life. This dissertation reports the experimental study of a unidirectional carbon fiber reinforced bismaleimide (BMI) composites (CFRC), an excellent candidate for high temperature aerospace components, undergoing thermal oxidation at 260 °C in air for over 3000 hours. The key focus of the work is to investigate the mechanical properties of the carbon fiber BMI composite subjected to thermal aging in three key aspects - first, studying its bulk flexural properties (in macro scale), second, characterizing the crack propagation along the fiber direction, representing the interfacial bonding strength between fiber and matrix (in micro scale), and third, introducing nano-structured materials to modify the interface (in nano scale) between the carbon fiber and BMI resin and mechanical characterization to study its influence on mitigating the aging effect. Under the first category, weight loss and flexural properties have been monitored as the oxidation propagates through the fiber/matrix interface. Dynamic mechanical analysis and micro-computed tomography analysis have been performed to analyze the aging effects. In the second category, the long-term effects of thermal oxidation on the delamination (between the composite plies) and debonding (between fiber and matrix) type fracture toughness have been characterized by preparing two distinct types of double cantilever beam specimens. Digital image correlation has been used to determine the deformation field and strain distribution around the crack propagation path. Finally the resin system and the fiber/matrix interface have been modified using nanomaterials to mitigate the degradations caused by oxidation. Nanoclay modified

  10. Three-dimensional carbon fibers and method and apparatus for their production

    DOEpatents

    Muradov, Nazim Z.

    2012-02-21

    This invention relates to novel three-dimensional (3D) carbon fibers which are original (or primary) carbon fibers (OCF) with secondary carbon filaments (SCF) grown thereon, and, if desired, tertiary carbon filaments (TCF) are grown from the surface of SCF forming a filamentous carbon network with high surface area. The methods and apparatus are provided for growing SCF on the OCF by thermal decomposition of carbonaceous gases (CG) over the hot surface of the OCF without use of metal-based catalysts. The thickness and length of SCF can be controlled by varying operational conditions of the process, e.g., the nature of CG, temperature, residence time, etc. The optional activation step enables one to produce 3D activated carbon fibers with high surface area. The method and apparatus are provided for growing TCF on the SCF by thermal decomposition of carbonaceous gases over the hot surface of the SCF using metal catalyst particles.

  11. Carbon fiber CVD coating by carbon nanostructured for space materials protection against atomic oxygen

    NASA Astrophysics Data System (ADS)

    Pastore, Roberto; Bueno Morles, Ramon; Micheli, Davide

    2016-07-01

    adhesion and durability in the environment. Though these coatings are efficient in protecting polymer composites, their application imposes severe constraints. Their thermal expansion coefficients may differ markedly from those of polymer composite substrates: as a result, cracks develop in the coatings on thermal cycling and AO can penetrate through them to the substrate. In addition to the technicalities of forming an effective barrier, such factors as cost, convenience of application and ease of repair are important considerations in the selection of a coating for a particular application. The latter issues drive the aerospace research toward the development of novel light composite materials, like the so called polymer nanocomposites, which are materials with a polymer matrix and a filler with at least one dimension less than 100 nanometers. Current interest in nanocomposites has been generated and maintained because nanoparticle-filled polymers exhibit unique combinations of properties not achievable with traditional composites. These combinations of properties can be achieved because of the small size of the fillers, the large surface area the fillers provide, and in many cases the unique properties of the fillers themselves. In particular, the carbon fiber-based polymeric composite materials are the basic point of interest: the aim of the present study is to find new solution to produce carbon fiber-based composites with even more upgraded performances. One intriguing strategy to tackle such an issue has been picked out in the coupling between the carbon fibers and the carbon nanostructures. That for two main reasons: first, carbon nanostructures have shown fancy potentialities for any kind of technological applications since their discovery, second, the chemical affinity between fiber and nanostructure (made of the same element) should be a likely route to approach the typical problems due to thermo-mechanical compatibility. This work is joined in such framework

  12. PAPER FIBERS AS A CARBON SOURCE FOR THE DE NOVO FORMATION OF POLYCHLORINATED DIOXINS AND FURANS

    EPA Science Inventory

    Formation of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzefurans (PCDDs/Fs) from carbons that were produced from pyrolysis of paper fibers and from a wood charcoal was investigated experimentally. Fibers obtained from a filter paper were pyrolyzed at 300 and 800 d...

  13. An assessment of national risk: General concepts and overall approach. [carbon fiber utilization in commercial aviation

    NASA Technical Reports Server (NTRS)

    Kalelkar, A. S.

    1979-01-01

    The analysis of risk presented by carbon fiber utilization in commercial aviation is reported. The discussion is presented in three parts: (1) general concepts; (2) overall approach; and (3) risk evaluation and perspective.

  14. Circuit models for Salisbury screens made from unidirectional carbon fiber composite sandwich structures

    NASA Astrophysics Data System (ADS)

    Riley, Elliot J.; Lenzing, Erik H.; Narayanan, Ram M.

    2016-05-01

    Carbon fiber composite materials have many useful structural material properties. The electromagnetic perfor- mance of these materials is of great interest for future applications. The work presented in this paper deals with the construction of Salisbury screen microwave absorbers made from unidirectional carbon fiber composite sand- wich structures. Specifically, absorbers centered at 7.25 GHz and 12.56 GHz are investigated. Circuit models are created to match the measured performance of the carbon fiber Salisbury screens using a genetic algorithm to extract lumped element circuit values. The screens presented in this paper utilize unidirectional carbon fiber sheets in place of the resistive sheet utilized in the classic Salisbury screen. The theory, models, prototypes, and measurements of these absorbers are discussed.

  15. Advanced in situ multi-scale characterization of hardness of carbon-fiber-reinforced plastic

    NASA Astrophysics Data System (ADS)

    Wang, Hongxin; Masuda, Hideki; Kitazawa, Hideaki; Onishi, Keiko; Kawai, Masamichi; Fujita, Daisuke

    2016-10-01

    In situ multi-scale characterization of hardness of carbon-fiber-reinforced plastic (CFRP) is demonstrated by a traditional hardness tester, instrumented indentation tester and atomic-force-microscope (AFM)-based nanoindentation. In particular, due to the large residual indentation and nonuniform distribution of the microscale carbon fibers, the Vickers hardness could not be calculated by the traditional hardness tester. In addition, the clear residual microindentation could not be formed on the CFRP by instrumented indentation tester because of the large tip half angle of the Berkovich indenter. Therefore, an efficient technique for characterizing the true nanoscale hardness of CFRP was proposed and evaluated. The local hardness of the carbon fibers or plastic matrix on the nanoscale did not vary with nanoindentation location. The Vickers hardnesses of the carbon fiber and plastic matrix determined by AFM-based nanoindentation were 340 ± 30 and 40 ± 2 kgf/mm2, respectively.

  16. Residual stresses in boron/tungsten and boron/carbon fibers

    NASA Technical Reports Server (NTRS)

    Behrendt, D. R.

    1977-01-01

    Longitudinal residual stress distribution is determined for 102-micron diam B/W and B/C fibers. The 102-micron diam B/W fibers are deposited on a 12.7-micron diam tungsten wire resistively heated in a BCl3-H2 reactor. The 102-micron diam B/C fibers are made by deposition of boron on a pyrolytic graphite-coated carbon fiber. The longitudinal residual stress distribution is calculated from measurements of the change in length of the fiber produced by removal of the surface through electropolishing. It is found that for both types of fibers, the residual stress vary from a compressive stress at the surface to a tensile stress in the boron near the core. Closer to the core and in the core, significant differences in the residual stresses are observed for the B/W and B/C fibers.

  17. Numerical and Experimental Investigations on Deep Drawing of G1151 Carbon Fiber Woven Composites

    NASA Astrophysics Data System (ADS)

    Gherissi, A.; Abbassi, F.; Ammar, A.; Zghal, A.

    2016-06-01

    This study proposes to simulate the deep drawing on carbon woven composites in order to reduce the manufacturing cost and waste of composite material during the stamping process, The multi-scale anisotropic approach of woven composite was used to develop a finite element model for simulating the orientation of fibers accurately and predicting the deformation of composite during mechanical tests and forming process. The proposed experimental investigation for bias test and hemispherical deep drawing process is investigated in the G1151 Interlock. The mechanical properties of carbon fiber have great influence on the deformation of carbon fiber composites. In this study, shear angle-displacement curves and shear load-shear angle curves were obtained from a bias extension test. Deep drawing experiments and simulation were conducted, and the shear load-displacement curves under different forming depths and shear angle-displacement curves were obtained. The results showed that the compression and shear between fibers bundles were the main deformation mechanism of carbon fiber woven composite, as well as the maximum shear angle for the composites with G1151 woven fiber was 58°. In addition, during the drawing process, it has been found that the forming depth has a significant influence on the drawing force. It increases rapidly with the increasing of forming depth. In this approach the suitable forming depth deep drawing of the sheet carbon fiber woven composite was approximately 45 mm.

  18. X-ray photoelectron spectroscopic studies of carbon fiber surfaces. 22. Comparison between surface treatment of untreated and previously surface-treated fibers

    SciTech Connect

    Wang, Y.Q.; Viswanathan, H.; Audi, A.A.; Sherwood, P.M.A.

    2000-04-01

    IM7 PAN-based carbon fibers, with a proprietary surface treatment applied by the manufacturer, were analyzed by X-ray photoelectron spectroscopy (XPS). The surface treatment applied by the manufacturer was removed by heating in a vacuum. The fibers detreated in this manner were then subjected to electrochemical treatment. The electrochemical behavior of the as-received fibers and detreated fibers were measured and analyzed. When the same electrochemical treatment was applied to the as-received fibers with their commercial surface treatment intact, a different surface chemistry was observed for the detreated fibers. This study shows that the surface chemistry of treated fibers depends closely on the initial surface chemistry of the fibers and its detreatment. This work shows the importance of using untreated or detreated fibers as precursors for applying reproducible surface treatment so that one can understand and control the surface chemistry of fibers and their interfacial interaction in composites.

  19. Quasi-Static Indentation Analysis of Carbon-Fiber Laminates.

    SciTech Connect

    Briggs, Timothy; English, Shawn Allen; Nelson, Stacy Michelle

    2015-12-01

    A series of quasi - static indentation experiments are conducted on carbon fiber reinforced polymer laminates with a systematic variation of thicknesses and fixture boundary conditions. Different deformation mechanisms and their resulting damage mechanisms are activated b y changing the thickn ess and boundary conditions. The quasi - static indentation experiments have been shown to achieve damage mechanisms similar to impact and penetration, however without strain rate effects. The low rate allows for the detailed analysis on the load response. Moreover, interrupted tests allow for the incremental analysis of various damage mechanisms and pr ogressions. The experimentally tested specimens are non - destructively evaluated (NDE) with optical imaging, ultrasonics and computed tomography. The load displacement responses and the NDE are then utilized in numerical simulations for the purpose of model validation and vetting. The accompanying numerical simulation work serves two purposes. First, the results further reveal the time sequence of events and the meaning behind load dro ps not clear from NDE . Second, the simulations demonstrate insufficiencies in the code and can then direct future efforts for development.

  20. Carbon Fiber Strand Tensile Failure Dynamic Event Characterization

    NASA Technical Reports Server (NTRS)

    Johnson, Kenneth L.; Reeder, James

    2016-01-01

    There are few if any clear, visual, and detailed images of carbon fiber strand failures under tension useful for determining mechanisms, sequences of events, different types of failure modes, etc. available to researchers. This makes discussion of physics of failure difficult. It was also desired to find out whether the test article-to-test rig interface (grip) played a part in some failures. These failures have nothing to do with stress rupture failure, thus representing a source of waste for the larger 13-00912 investigation into that specific failure type. Being able to identify or mitigate any competing failure modes would improve the value of the 13-00912 test data. The beginnings of the solution to these problems lay in obtaining images of strand failures useful for understanding physics of failure and the events leading up to failure. Necessary steps include identifying imaging techniques that result in useful data, using those techniques to home in on where in a strand and when in the sequence of events one should obtain imaging data.

  1. Enrichment of ventilation air methane (VAM) with carbon fiber composites.

    PubMed

    Bae, Jun-Seok; Su, Shi; Yu, Xin Xiang

    2014-05-20

    Treatment of ventilation air methane (VAM) with cost-effective technologies has been an ongoing challenge due to its high volumetric flow rate with low and variable methane concentrations. In this work, honeycomb monolithic carbon fiber composites were developed and employed to capture VAM with a large-scale test unit at various conditions such as VAM concentration, ventilation air (VA) flow rate, temperature, and purging fluids. Regardless of inlet VAM concentrations, methane was captured at almost 100%. To regenerate the composites, the initial vacuum swing followed by combined temperature and vacuum swing adsorption (TVSA) was applied. It was found that initial vacuum swing is a control step for the final methane concentration having 5 or 11 times the VAM enrichment by one-step adsorption, which is, to our knowledge, the best performance achieved in VAM enrichment technologies worldwide. Five-time enriched VAM can be utilized as a principle fuel for lean burn turbine. Also, it can be further enriched by second step adsorption to more than 25% which then can be used for commercially available gas engines. In this way, the final product can be out of the methane explosive range (5-15%). PMID:24787090

  2. Repairable Woven Carbon Fiber Composites with Full Recyclability Enabled by Malleable Polyimine Networks.

    PubMed

    Taynton, Philip; Ni, Huagang; Zhu, Chengpu; Yu, Kai; Loob, Samuel; Jin, Yinghua; Qi, H Jerry; Zhang, Wei

    2016-04-20

    Carbon-fiber reinforced composites are prepared using catalyst-free malleable polyimine networks as binders. An energy neutral closed-loop recycling process has been developed, enabling recovery of 100% of the imine components and carbon fibers in their original form. Polyimine films made using >21% recycled content exhibit no loss of mechanical performance, therefore indicating all of the thermoset composite material can be recycled and reused for the same purpose. PMID:26875745

  3. Repairable Woven Carbon Fiber Composites with Full Recyclability Enabled by Malleable Polyimine Networks.

    PubMed

    Taynton, Philip; Ni, Huagang; Zhu, Chengpu; Yu, Kai; Loob, Samuel; Jin, Yinghua; Qi, H Jerry; Zhang, Wei

    2016-04-20

    Carbon-fiber reinforced composites are prepared using catalyst-free malleable polyimine networks as binders. An energy neutral closed-loop recycling process has been developed, enabling recovery of 100% of the imine components and carbon fibers in their original form. Polyimine films made using >21% recycled content exhibit no loss of mechanical performance, therefore indicating all of the thermoset composite material can be recycled and reused for the same purpose.

  4. Electrospinning of calcium carbonate fibers and their conversion to nanocrystalline hydroxyapatite.

    PubMed

    Holopainen, Jani; Santala, Eero; Heikkilä, Mikko; Ritala, Mikko

    2014-12-01

    Calcium carbonate (CaCO3) fibers were prepared by electrospinning followed by annealing. Solutions consisting of calcium nitrate tetrahydrate (Ca(NO3)2·4H2O) and polyvinylpyrrolidone (PVP) dissolved in ethanol or 2-methoxyethanol were used for the fiber preparation. By varying the precursor concentrations in the electrospinning solutions CaCO3 fibers with average diameters from 140 to 290 nm were obtained. After calcination the fibers were identified as calcite by X-ray diffraction (XRD). The calcination process was studied in detail with high temperature X-ray diffraction (HTXRD) and thermogravimetric analysis (TGA). The initially weak fiber-to-substrate adhesion was improved by adding a strengthening CaCO3 layer by spin or dip coating Ca(NO3)2/PVP precursor solution on the CaCO3 fibers followed by annealing of the gel formed inside the fiber layer. The CaCO3 fibers were converted to nanocrystalline hydroxyapatite (HA) fibers by treatment in a dilute phosphate solution. The resulting hydroxyapatite had a plate-like crystal structure with resemblance to bone mineral. The calcium carbonate and hydroxyapatite fibers are interesting materials for bone scaffolds and bioactive coatings.

  5. Experimental determinations of the eigenmodes for composite bars made with carbon and Kevlar-carbon fibers

    NASA Astrophysics Data System (ADS)

    Miriţoiu, C. M.; Stănescu, M. M.; Burada, C. O.; Bolcu, D.; Roşca, V.

    2015-11-01

    For modal identification, the single-point excitation method has been widely used in modal tests and it consists in applying a force in a given point and recording the vibratory structure response in all interest points, including the excitation point. There will be presented the experimental recordings for the studied bars (with Kevlar-carbon or carbon fibers), the frequency response function in Cartesian and polar coordinates. By using the frequency response functions we determine the eigenparameters for each bar. We present the final panel of the eigenmodes (with the damping factors, eigenfrequencies and critical damping) for each considered bar. Using the eigenfrequency of the first determined eigenmode, the bars stiffness has been determined. The presented bars can be used in practical engineering for: car or bus body parts, planes body parts, bullet-proof vests, reinforcements for sandwich beams, and so on.

  6. Electroadsorption desalination with carbon nanotube/PAN-based carbon fiber felt composites as electrodes.

    PubMed

    Liu, Yang; Zhou, Junbo

    2014-01-01

    The chemical vapor deposition method is used to prepare CNT (carbon nanotube)/PCF (PAN-based carbon fiber felt) composite electrodes in this paper, with the surface morphology of CNT/PCF composites and electroadsorption desalination performance being studied. Results show such electrode materials with three-dimensional network nanostructures having a larger specific surface area and narrower micropore distribution, with a huge number of reactive groups covering the surface. Compared with PCF electrodes, CNT/PCF can allow for a higher adsorption and desorption rate but lower energy consumption; meanwhile, under the condition of the same voltage change, the CNT/PCF electrodes are provided with a better desalination effect. The study also found that the higher the original concentration of the solution, the greater the adsorption capacity and the lower the adsorption rate. At the same time, the higher the solution's pH, the better the desalting; the smaller the ions' radius, the greater the amount of adsorption.

  7. Nomex-derived activated carbon fibers as electrode materials in carbon based supercapacitors

    NASA Astrophysics Data System (ADS)

    Leitner, K.; Lerf, A.; Winter, M.; Besenhard, J. O.; Villar-Rodil, S.; Suárez-García, F.; Martínez-Alonso, A.; Tascón, J. M. D.

    Electrochemical characterization has been carried out for electrodes prepared of several activated carbon fiber samples derived from poly (m-phenylene isophthalamide) (Nomex) in an aqueous solution. Depending on the burn-off due to activation the BET surface area of the carbons was in the order of 1300-2800 m 2 g -1, providing an extensive network of micropores. Their capability as active material for supercapacitors was evaluated by using cyclic voltammetry and impedance spectroscopy. Values for the capacitance of 175 F g -1 in sulfuric acid were obtained. Further on, it was observed that the specific capacitance and the performance of the electrode increase significantly with increasing burn-off degree. We believe that this fact can be attributed to the increase of surface area and porosity with increasing burn-off.

  8. Interfacial engineering of the interphase between carbon fibers and vinyl ester resin

    NASA Astrophysics Data System (ADS)

    Xu, Lanhong

    Vinyl ester resins have been extensively used for the manufacture of low cost high performance composites. Carbon fibers are important reinforcement materials. The use of vinyl ester composites reinforced with carbon fibers requires an improvement in the fiber/matrix adhesion levels. The objectives of this study were to gain an understanding of the factors controlling interfacial adhesion between carbon fibers and vinyl ester resin; to model the contributions of the factors controlling fiber/matrix adhesion; and to provide an engineered and optimized interface between carbon fiber and vinyl ester for tailoring structurally efficient carbon fiber/vinyl ester composites. This work consists of three parts. Part I. A partially cross-linked DGEBA epoxy polymer sizing placed onto carbon fiber surface was found to be a beneficial interphase between the carbon fiber and vinyl ester resin resulting in an increase in fiber-matrix adhesion. The adhesion was evaluated as interfacial shear strength (IFSS) with micro-indentation. Nano-indentation and nano-scratch technique were used to investigate the gradient between this epoxy sizing and vinyl ester resin. An optimized thickness of this sizing was found and the mechanism by which this sizing improved adhesion was also investigated. A set of 2-D non-linear finite element models was set up for simulation of the micro-indentation process and consistent results were found between the experimental data and numerical results. It was found that the epoxy sizing formed more chemical bonds with the surface of the carbon fiber reinforcement and an interpenetrating interphase with the vinyl ester resin. The resulting interphase between vinyl ester matrix and epoxy sizing reduced the residual stress caused by the volume shrinkage of the vinyl ester after curing. Part II. Since it is known that the carbon fiber surface can interfere with the vinyl ester polymerization, the effects of preferential adsorption of the catalysts and styrene on

  9. High Per formance and Flexible Supercapacitors based on Carbonized Bamboo Fibers for Wide Temperature Applications

    PubMed Central

    Zequine, Camila; Ranaweera, C. K.; Wang, Z.; Singh, Sweta; Tripathi, Prashant; Srivastava, O. N.; Gupta, Bipin Kumar; Ramasamy, K.; Kahol, P. K.; Dvornic, P. R.; Gupta, Ram K.

    2016-01-01

    High performance carbonized bamboo fibers were synthesized for a wide range of temperature dependent energy storage applications. The structural and electrochemical properties of the carbonized bamboo fibers were studied for flexible supercapacitor applications. The galvanostatic charge-discharge studies on carbonized fibers exhibited specific capacity of ~510F/g at 0.4 A/g with energy density of 54 Wh/kg. Interestingly, the carbonized bamboo fibers displayed excellent charge storage stability without any appreciable degradation in charge storage capacity over 5,000 charge-discharge cycles. The symmetrical supercapacitor device fabricated using these carbonized bamboo fibers exhibited an areal capacitance of ~1.55 F/cm2 at room temperature. In addition to high charge storage capacity and cyclic stability, the device showed excellent flexibility without any degradation to charge storage capacity on bending the electrode. The performance of the supercapacitor device exhibited ~65% improvement at 70 °C compare to that at 10 °C. Our studies suggest that carbonized bamboo fibers are promising candidates for stable, high performance and flexible supercapacitor devices. PMID:27546225

  10. High Per formance and Flexible Supercapacitors based on Carbonized Bamboo Fibers for Wide Temperature Applications.

    PubMed

    Zequine, Camila; Ranaweera, C K; Wang, Z; Singh, Sweta; Tripathi, Prashant; Srivastava, O N; Gupta, Bipin Kumar; Ramasamy, K; Kahol, P K; Dvornic, P R; Gupta, Ram K

    2016-01-01

    High performance carbonized bamboo fibers were synthesized for a wide range of temperature dependent energy storage applications. The structural and electrochemical properties of the carbonized bamboo fibers were studied for flexible supercapacitor applications. The galvanostatic charge-discharge studies on carbonized fibers exhibited specific capacity of ~510F/g at 0.4 A/g with energy density of 54 Wh/kg. Interestingly, the carbonized bamboo fibers displayed excellent charge storage stability without any appreciable degradation in charge storage capacity over 5,000 charge-discharge cycles. The symmetrical supercapacitor device fabricated using these carbonized bamboo fibers exhibited an areal capacitance of ~1.55 F/cm(2) at room temperature. In addition to high charge storage capacity and cyclic stability, the device showed excellent flexibility without any degradation to charge storage capacity on bending the electrode. The performance of the supercapacitor device exhibited ~65% improvement at 70 °C compare to that at 10 °C. Our studies suggest that carbonized bamboo fibers are promising candidates for stable, high performance and flexible supercapacitor devices. PMID:27546225

  11. Effect of different dispersants in compressive strength of carbon fiber cementitious composites

    NASA Astrophysics Data System (ADS)

    Lestari, Yulinda; Bahri, Saiful; Sugiarti, Eni; Ramadhan, Gilang; Akbar, Ari Yustisia; Martides, Erie; Khaerudini, Deni S.

    2013-09-01

    Carbon Fiber Cementitious Composites (CFCC) is one of the most important materials in smart concrete applications. CFCC should be able to have the piezoresistivity properties where its resistivity changes when there is applied a stress/strain. It must also have the compressive strength qualification. One of the important additives in carbon fiber cementitious composites is dispersant. Dispersion of carbon fiber is one of the key problems in fabricating piezoresistive carbon fiber cementitious composites. In this research, the uses of dispersants are methylcellulose, mixture of defoamer and methylcellulose and superplasticizer based polycarboxylate. The preparation of composite samples is similar as in the mortar technique according to the ASTM C 109/109M standard. The additives material are PAN type carbon fibers, methylcellulose, defoamer and superplasticizer (as water reducer and dispersant). The experimental testing conducts the compressive strength and resistivity at various curing time, i.e. 3, 7 and 28 days. The results obtained that the highest compressive strength value in is for the mortar using superplasticizer based polycarboxylate dispersant. This also shown that the distribution of carbon fiber with superplasticizer is more effective, since not reacting with the cementitious material which was different from the methylcellulose that creates the cement hydration reaction. The research also found that the CFCC require the proper water cement ratio otherwise the compressive strength becomes lower.

  12. High Per formance and Flexible Supercapacitors based on Carbonized Bamboo Fibers for Wide Temperature Applications

    NASA Astrophysics Data System (ADS)

    Zequine, Camila; Ranaweera, C. K.; Wang, Z.; Singh, Sweta; Tripathi, Prashant; Srivastava, O. N.; Gupta, Bipin Kumar; Ramasamy, K.; Kahol, P. K.; Dvornic, P. R.; Gupta, Ram K.

    2016-08-01

    High performance carbonized bamboo fibers were synthesized for a wide range of temperature dependent energy storage applications. The structural and electrochemical properties of the carbonized bamboo fibers were studied for flexible supercapacitor applications. The galvanostatic charge-discharge studies on carbonized fibers exhibited specific capacity of ~510F/g at 0.4 A/g with energy density of 54 Wh/kg. Interestingly, the carbonized bamboo fibers displayed excellent charge storage stability without any appreciable degradation in charge storage capacity over 5,000 charge-discharge cycles. The symmetrical supercapacitor device fabricated using these carbonized bamboo fibers exhibited an areal capacitance of ~1.55 F/cm2 at room temperature. In addition to high charge storage capacity and cyclic stability, the device showed excellent flexibility without any degradation to charge storage capacity on bending the electrode. The performance of the supercapacitor device exhibited ~65% improvement at 70 °C compare to that at 10 °C. Our studies suggest that carbonized bamboo fibers are promising candidates for stable, high performance and flexible supercapacitor devices.

  13. Effect of Hybrid Surface Modifications on Tensile Properties of Polyacrylonitrile- and Pitch-Based Carbon Fibers

    NASA Astrophysics Data System (ADS)

    Naito, Kimiyoshi

    2016-05-01

    Recent interest has emerged in techniques that modify the surfaces of carbon fibers, such as carbon nanotube (CNT) grafting or polymer coating. Hybridization of these surface modifications has the potential to generate highly tunable, high-performance materials. In this study, the mechanical properties of surface-modified polyacrylonitrile (PAN)-based and pitch-based carbon fibers were investigated. Single-filament tensile tests were performed for fibers modified by CNT grafting, dipped polyimide coating, high-temperature vapor deposition polymerized polyimide coating, grafting-dipping hybridization, and grafting-vapor deposition hybridization. The Weibull statistical distributions of the tensile strengths of the surface-modified PAN- and pitch-based carbon fibers were examined. All surface modifications, especially hybrid modifications, improved the tensile strengths and Weibull moduli of the carbon fibers. The results exhibited a linear relationship between the Weibull modulus and average tensile strength on a log-log scale for all surface-modified PAN- and pitch-based carbon fibers.

  14. Lignin-Derived Carbon Fiber as a Co-Product of Refining Cellulosic Biomass

    SciTech Connect

    Langholtz, Matthew H.; Downing, Mark; Graham, Robin Lambert; Baker, Fred S.; Compere, Alicia L.; William L. Griffith; Boeman, Raymond G.; Keller, Martin

    2014-01-15

    Lignin by-products from biorefineries has the potential to provide a low-cost alternative to petroleum-based precursors to manufacture carbon fiber, which can be combined with a binding matrix to produce a structural material with much greater specific strength and specific stiffness than conventional materials such as steel and aluminum. The market for carbon fiber is universally projected to grow exponentially to fill the needs of clean energy technologies such as wind turbines and to improve the fuel economies in vehicles through lightweighting. In addition to cellulosic biofuel production, lignin-based carbon fiber production coupled with biorefineries may provide $2,400 to $3,600 added value dry Mg-1 of biomass for vehicle applications. Compared to producing ethanol alone, the addition of lignin-derived carbon fiber could increase biorefinery gross revenue by 30% to 300%. Using lignin-derived carbon fiber in 15 million vehicles per year in the US could reduce fossil fuel consumption by 2-5 billion liters year-1, reduce CO2 emissions by about 6.7 million Mg year-1, and realize fuel savings through vehicle lightweighting of $700 to $1,600 per Mg biomass processed. The value of fuel savings from vehicle lightweighting becomes economical at carbon fiber price of $6.60 kg-1 under current fuel prices, or $13.20 kg-1 under fuel prices of about $1.16 l-1.

  15. Risk to the public from carbon fibers released in civil aircraft accidents

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Because carbon fibers are strong, stiff, and lightweight, they are attractive for use in composite structures. Because they also have high electrical conductivity, free carbon fibers settling on electrical conductors can cause malfunctions. If released from the composite by burning, the fibers may become a hazard to exposed electrical and electronic equipment. As part of a Federal study of the potential hazard associated with the use of carbon fibers, NASA assessed the public risk associated with crash fire accidents of civil aircraft. The NASA study projected a dramatic increase in the use of carbon composites in civil aircraft and developed technical data to support the risk assessment. Personal injury was found to be extremely unlikely. In 1993, the year chosen as a focus for the study, the expected annual cost of damage caused by released carbon fibers is only $1000. Even the worst-case carbon fiber incident simulated (costing $178,000 once in 34,000 years) was relatively low-cost compared with the usual air transport accident cost. On the basis of these observations, the NASA study concluded that exploitation of composites should continue, that additional protection of avionics is unnecessary, and that development of alternate materials specifically to overcome this problem is not justified.

  16. Fracture Toughness of Carbon Fiber Composites Containing Various Fiber Sizings and a Puncture Self-Healing Thermoplastic Matrix

    NASA Technical Reports Server (NTRS)

    Cano, Roberto J.; Grimsley, Brian W.; Ratcliffe, James G.; Gordon, Keith L.; Smith, Joseph G.; Siochi, Emilie J.

    2015-01-01

    Ongoing efforts at NASA Langley Research Center (LaRC) have resulted in the identification of several commercially available thermoplastic resin systems which self-heal after ballistic impact and through penetration. One of these resins, polybutylene graft copolymer (PBg), was selected as a matrix for processing with unsized carbon fibers to fabricate reinforced composites for further evaluation. During process development, data from thermo-physical analyses was utilized to determine a processing cycle to fabricate laminate panels, which were analyzed by photo microscopy and acid digestion. The process cycle was further optimized based on these results to fabricate panels for mechanical property characterization. The results of the processing development effort of this composite material, as well as the results of the mechanical property characterization, indicated that bonding between the fiber and PBg was not adequate. Therefore, three sizings were investigated in this work to assess their potential to improve fiber/matrix bonding compared to previously tested unsized IM7 fiber. Unidirectional prepreg was made at NASA LaRC from three sized carbon fibers and utilized to fabricate test coupons that were tested in double cantilever beam configurations to determine GIc fracture toughness.

  17. The potential for damage from the accidental release of conductive carbon fibers from aircraft composites

    NASA Technical Reports Server (NTRS)

    Bell, V. L.

    1980-01-01

    Carbon and graphite fibers are known to be electrically conductive. The rapidly accelerating use of carbon fibers as the reinforcement in filamentary composite materials brought up the possibility of accidental release of carbon fibers from the burning of crashed commercial airliners with carbon composite parts. Such release could conceivably cause widespread damage to electrical and electronic equipment. The experimental and analytical results of a comprehensive investigation of the various elements necessary to assess the extent of such potential damage in terms of annual expected costs and maximum losses at low probabilities of occurrence are presented. A review of NASA materials research program to provide alternate or modified composite materials to overcome any electrical hazards from the use of carbon composites in aircraft structures is described.

  18. Research on the melt impregnation of continuous carbon fiber reinforced nylon 66 composites

    NASA Astrophysics Data System (ADS)

    Jia, M. Y.; Li, C. X.; Xue, P.; Chen, K.; Chen, T. H.

    2016-07-01

    Impregnation mold of continuous carbon fiber reinforced thermoplastic composites was designed and built in the article. Based on the theory of fluid mechanics and Darcy's law, a model of the melt impregnation was also established. The influences of fiber bundle width and impregnation pins’ diameter on the impregnation degree were studied by numerical simulation. Continuous carbon fiber reinforced nylon 66 composites were prepared. The effects of coated angle and impregnation mold temperature on the mechanical properties of the composites were also described.The agreement between the experimental data and prediction by the model was found to be satisfactory.

  19. Complementary methods for nondestructive testing of composite materials reinforced with carbon woven fibers

    NASA Astrophysics Data System (ADS)

    Steigmann, R.; Iftimie, N.; Sturm, R.; Vizureanu, P.; Savin, A.

    2015-11-01

    This paper presents complementary methods used in nondestructive evaluation (NDE) of composite materials reinforced with carbon woven fibers as two electromagnetic methods using sensor with orthogonal coils and sensor with metamaterials lens as well as ultrasound phased array method and Fiber Bragg gratings embedded instead of a carbon fiber for better health monitoring. The samples were impacted with low energy in order to study delamination influence. The electromagnetic behavior of composite was simulated by finite- difference time-domain (FDTD) software, showing a very good concordance with electromagnetic nondestructive evaluation tests.

  20. Thermophysical ESEM and TEM Characterization of Carbon Fibers CTE, Spectroscopy and Roughness Studies at High Temperatures

    NASA Technical Reports Server (NTRS)

    Ochoa, Ozden O.

    2004-01-01

    Accurate determination of the transverse properties of carbon fibers is important for assessment and prediction of local material as well as global structural response of composite components. However the measurements are extremely difficult due to the very small diameters of the fibers (few microns only) and must be conducted within a microscope. In this work, environmental scanning electron microscope (ESEM) and transmission electron microscope (TEM) are used to determine the transverse coefficient of thermal expansion of different carbon fibers as a function of temperature.

  1. Macroscopic nanotube fibers spun from single-walled carbon nanotube polyelectrolytes.

    PubMed

    Jiang, Chengmin; Saha, Avishek; Young, Colin C; Hashim, Daniel Paul; Ramirez, Carolyn E; Ajayan, Pulickel M; Pasquali, Matteo; Martí, Angel A

    2014-09-23

    In this work, single-walled carbon nanotube (SWCNT) fibers were produced from SWCNT polyelectrolyte dispersions stabilized by crown ether in dimethyl sulfoxide and coagulated into aqueous solutions. The SWCNT polyelectrolyte dispersions had concentrations up to 52 mg/mL and showed liquid crystalline behavior under polarized optical microscopy. The produced SWCNT fibers are neat (i.e., not forming composites with polymers) and showed a tensile strength up to 124 MPa and a Young's modulus of 14 GPa. This tensile strength is comparable to those of SWCNT fibers spun from strong acids. Conductivities on the order of 10(4) S/m were obtained by doping the fibers with iodine.

  2. Mixed polyvalent-monovalent metal coating for carbon-graphite fibers

    NASA Technical Reports Server (NTRS)

    Harper-Tervet, J.; Tervet, F. W.; Humphrey, M. F. (Inventor)

    1982-01-01

    An improved coating of gasification catalyst for carbon-graphite fibers is provided comprising a mixture of a polyvalent metal such as calcium and a monovalent metal such as lithium. The addition of lithium provides a lighter coating and a more flexible coating when applied to a coating of a carboxyl containing resin such as polyacrylic acid since it reduces the crosslink density. Furthermore, the presence of lithium provides a glass-like substance during combustion which holds the fiber together resulting in slow, even combustion with much reduced evolution of conductive fragments. The coated fibers are utilized as fiber reinforcement for composites.

  3. A novel surface modification of carbon fiber for high-performance thermoplastic polyurethane composites

    NASA Astrophysics Data System (ADS)

    Zhang, Yuanyuan; Zhang, Yizhen; Liu, Yuan; Wang, Xinling; Yang, Bin

    2016-09-01

    Properties of carbon fiber (CF) reinforced composites depend largely on the interfacial bonding strength between fiber and the matrix. In the present work, CF was grafted by 4,4‧-diphenylmethane diisocyanate (MDI) molecules after electrochemical oxidation treatment. The existence of functional groups introduced to the fiber surface and the changes of surface roughness were confirmed by FTIR, AFM, XPS, SEM and Raman spectroscopy. To evaluate the possible applications of this surface modification of carbon fiber, we examined the mechanical properties as well as the friction and wear performance of pristine CF and MDI-CF reinforced thermoplastic polyurethane (TPU) composites with 5-30 wt.% fiber contents, and found that the mechanical properties of TPU composites were all significantly improved. It is remarkable that when fiber content was 30 wt.%, the tensile strength of TPU/MDI-CF was increased by 99.3%, which was greater than TPU/CF (53.2%), and the friction loss of TPU/MDI-CF was decreased by 49.09%. The results of DMA and SEM analysis indicated the positive effects of MDI modification on the interfacial bonding between fibers and matrix. We believed that this simple and effective method could be used to the development of surface modified carbon fiber for high-performance TPU.

  4. Large and stable emission current from synthesized carbon nanotube/fiber network

    SciTech Connect

    Di, Yunsong; Xiao, Mei; Zhang, Xiaobing Wang, Qilong; Li, Chen; Lei, Wei; Cui, Yunkang

    2014-02-14

    In order to obtain a large and stable electron field emission current, the carbon nanotubes have been synthesized on carbon fibers by cold wall chemical vapor deposition method. In the hierarchical nanostructures, carbon fibers are entangled together to form a conductive network, it could provide excellent electron transmission and adhesion property between electrode and emitters, dispersed clusters of carbon nanotubes with smaller diameters have been synthesized on the top of carbon fibers as field emitters, this kind of emitter distribution could alleviate electrostatic shielding effect and protect emitters from being wholly destroyed. Field emission properties of this kind of carbon nanotube/fiber network have been tested, up to 30 mA emission current at an applied electric field of 6.4 V/μm was emitted from as-prepared hierarchical nanostructures. Small current degradation at large emission current output by DC power operation indicated that carbon nanotube/fiber network could be a promising candidate for field emission electron source.

  5. Preparation of Fiber Based Binder Materials to Enhance the Gas Adsorption Efficiency of Carbon Air Filter.

    PubMed

    Lim, Tae Hwan; Choi, Jeong Rak; Lim, Dae Young; Lee, So Hee; Yeo, Sang Young

    2015-10-01

    Fiber binder adapted carbon air filter is prepared to increase gas adsorption efficiency and environmental stability. The filter prevents harmful gases, as well as particle dusts in the air from entering the body when a human inhales. The basic structure of carbon air filter is composed of spunbond/meltblown/activated carbon/bottom substrate. Activated carbons and meltblown layer are adapted to increase gas adsorption and dust filtration efficiency, respectively. Liquid type adhesive is used in the conventional carbon air filter as a binder material between activated carbons and other layers. However, it is thought that the liquid binder is not an ideal material with respect to its bonding strength and liquid flow behavior that reduce gas adsorption efficiency. To overcome these disadvantages, fiber type binder is introduced in our study. It is confirmed that fiber type binder adapted air filter media show higher strip strength, and their gas adsorption efficiencies are measured over 42% during 60 sec. These values are higher than those of conventional filter. Although the differential pressure of fiber binder adapted air filter is relatively high compared to the conventional one, short fibers have a good potential as a binder materials of activated carbon based air filter.

  6. Development of Carbon Fiber Reinforced Stellite Alloy Based Composites for Tribocorrosion Applications

    NASA Astrophysics Data System (ADS)

    Khoddamzadeh, Alireza

    This thesis reports the design and development of two classes of new composite materials, which are low-carbon Stellite alloy matrices, reinforced with either chopped plain carbon fiber or chopped nickel-coated carbon fiber. The focus of this research is on obviating the problems related to the presence of carbides in Stellite alloys by substituting carbides as the main strengthening agent in Stellite alloys with the aforementioned carbon fibers. Stellite 25 was selected as the matrix because of its very low carbon content (0.1 wt%) and thereby relatively carbide free microstructure. The nickel coating was intended to eliminate any chance of carbide formation due to the possible reaction between carbon fibers and the matrix alloying additions. The composite specimens were fabricated using the designed hot isostatic pressing and sintering cycles. The fabricated specimens were microstructurally analyzed in order to identify the main phases present in the specimens and also to determine the possible carbide formation from the carbon fibers. The material characterization of the specimens was achieved through density, hardness, microhardness, corrosion, wear, friction, and thermal conductivity tests. These novel materials exhibit superior properties compared to existing Stellite alloys and are expected to spawn a new generation of materials used for high temperature, severe corrosion, and wear resistant applications in various industries.

  7. Conversion of lignin precursors to carbon fibers with nanoscale graphitic domains

    SciTech Connect

    Chatterjee, Sabornie; Jones, Eric B; Clingenpeel, Amy; McKenna, Amy; Rios, Orlando; McNutt, Nicholas W; Keffer, David J.; Johs, Alexander

    2014-08-04

    Lignin is one of the most abundant and inexpensive natural biopolymers. It can be efficiently converted to low cost carbon fiber, monolithic structures or powders that could be used directly in the production of anodes for lithium-ion batteries. In this work, we report processing parameters relevant for the conversion of lignin precursors into electrochemically active carbon fibers, the impact of lignin precursor modification on melt processing and the microstructure of the final carbon material. The conversion process encompasses melt spinning of the lignin precursor, oxidative stabilization and a low temperature carbonization step in a nitrogen/hydrogen atmosphere. To assess electrochemical performance, we determined resistivities of individual carbon fiber samples and characterized the microstructure by scanning electron microscopy and neutron diffraction. The chemical modification and subsequent thermomechanical processing methods reported here are effective for conversion into carbon fibers while preserving the macromolecular backbone structure of lignin. Modification of softwood lignin produced functionalities and rheological properties that more closely resemble hardwood lignin thereby enabling the melt processing of softwood lignin in oxidative atmospheres (air). Structural characterization of the carbonized fibers reveals nanoscale graphitic domains that are linked to enhanced electrochemical performance.

  8. Carbonic anhydrase immobilized on hollow fiber membranes using glutaraldehyde activated chitosan for artificial lung applications

    PubMed Central

    Kimmel, J. D.; Arazawa, D. T.; Ye, S.-H.; Shankarraman, V.; Wagner, W. R.

    2013-01-01

    Extracorporeal CO2 removal from circulating blood is a promising therapeutic modality for the treatment of acute respiratory failure. The enzyme carbonic anhydrase accelerates CO2 removal within gas exchange devices by locally catalyzing HCO3− into gaseous CO2 within the blood. In this work, we covalently immobilized carbonic anhydrase on the surface of polypropylene hollow fiber membranes using glutaraldehyde activated chitosan tethering to amplify the density of reactive amine functional groups for enzyme immobilization. XPS and a colorimetric amine assay confirmed higher amine densities on the chitosan coated fiber compared to control fiber. Chitosan/CA coated fibers exhibited accelerated CO2 removal in scaled-down gas exchange devices in buffer and blood (115 % enhancement vs. control, 37 % enhancement vs. control, respectively). Carbonic anhydrase immobilized directly on hollow fiber membranes without chitosan tethering resulted in no enhancement in CO2 removal. Additionally, fibers coated with chitosan/carbonic anhydrase demonstrated reduced platelet adhesion when exposed to blood compared to control and heparin coated fibers. PMID:23888352

  9. A method to remove intercalates from bromine and iodine intercalated carbon fibers

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    1993-01-01

    Upon exposure to room-temperature fluorine, intercalated carbon fibers (containing either bromine alone or iodine and bromine together) become heavier and less stable. For Amoco P-100 graphitized carbon fibers which were intercalated with 18 percent bromine by weight, 1 hr of fluorine exposure results in a large weight increase, but causes only a small decrease in thermal stability. More than l hr of fluorine exposure time results in small additional increases in fiber weight, but significant further decreases in fiber thermal stability. Such phenomena do not occur if the fluorine exposure is at 250 C. These observations suggest the mechanism that at room temperature, fluorine is absorbed quickly by the intercalated fibers and intercalated slowly into the fibers. Most of the original intercalates are replaced by fluorine in the process of fluorine intercalation. Under an inert environment, the bromine intercalated fibers are much more thermally stable. After 800 C vacuum heating for two weeks, the brominated fibers lost about 45 percent of their bromine, and their resistivity increased from 64 omega-cm to a range of 95 to 170 micro omega-cm. This is still much lower than the 300 micro omega-cm value for pristine P-100. For practical purposes, in order to preserve their thermal stability, brominated fibers need to be protected from exposure to fluorine at room temperature, or to any intercalate at a temperature where, upon direct contact to graphite, an intercalation compound can easily be formed.

  10. Preparation and characterization of photocatalytic carbon dots-sensitized electrospun titania nanostructured fibers

    SciTech Connect

    Li, Haopeng; Zhu, Yihua; Cao, Huimin; Yang, Xiaoling; Li, Chunzhong

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► The TiO{sub 2}-CDs nanostructured fibers are fabricated by using APS combining the electrospinning TiO{sub 2} nanostructured fibers and CDs. ► The CD can work as a photosensitizer in the degradation of rhodamine B under visible light irradiation. ► The TiO{sub 2}-CDs nanostructured fibers exhibit enhanced photocatalytic efficiency and can be easily handled and recycled. -- Abstract: The carbon dots (CDs) are new functional carbon-aceous materials. Compared to conventional dye molecules and semiconductor quantum dots, CDs are superior in chemical inertness and low toxicity. The TiO{sub 2}-CDs nanostructured fibers were fabricated by combining the electrospinning technique and reflux method. Compared with the pure TiO{sub 2} nanostructured fibers and P25, the TiO{sub 2}-CDs nanostructured fibers exhibited enhanced photocatalytic efficiency of photodegradation of rhodamine B (RhB) under visible light irradiation. The enhanced photocatalytic activity of TiO{sub 2}-CDs nanostructured fibers could be attributed to the presence of CDs embedded in TiO{sub 2} nanostructured fibers. The CD can work as a photosensitizer in the degradation. Furthermore, the TiO{sub 2}-CDs nanostructured fibers could be easily handled and recycled due to their one-dimensional nanostructural property.

  11. [Preparation of carbon fiber reinforced fluid type resin denture (author's transl)].

    PubMed

    Kasuga, H; Sato, H; Nakabayashi, N

    1980-01-01

    Transverse strength of cured fluid resins is weaker than that of the heat cured. We have studied to improve the mechanical strength of self-cured acrylic resin by application of carbon fibers as reinforcement and simple methods which must be acceptable for technicians are proposed. A cloth type carbon fiber was the best reinforcement among studied carbon fibers such as chopped or mat. The chopped fibers were difficult to mix homogeneously with fluid resins and effectiveness of the reinforcement was low. Breaking often occurred at the interface between the reinforcement and resin in the cases of mat which gave defects to the test specimens. To prepare reinforced denture, the cloth was trimmed on the master cast after removal of wax and the prepreg was formed with the alginate impression on the cast by Palapress and the cloth. Other steps were same as the usual fluid resin. PMID:6929856

  12. [Preparation of carbon fiber reinforced fluid type resin denture (author's transl)].

    PubMed

    Kasuga, H; Sato, H; Nakabayashi, N

    1980-01-01

    Transverse strength of cured fluid resins is weaker than that of the heat cured. We have studied to improve the mechanical strength of self-cured acrylic resin by application of carbon fibers as reinforcement and simple methods which must be acceptable for technicians are proposed. A cloth type carbon fiber was the best reinforcement among studied carbon fibers such as chopped or mat. The chopped fibers were difficult to mix homogeneously with fluid resins and effectiveness of the reinforcement was low. Breaking often occurred at the interface between the reinforcement and resin in the cases of mat which gave defects to the test specimens. To prepare reinforced denture, the cloth was trimmed on the master cast after removal of wax and the prepreg was formed with the alginate impression on the cast by Palapress and the cloth. Other steps were same as the usual fluid resin.

  13. Formation and chemical reactivity of carbon fibers prepared by defluorination of graphite fluoride

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    1994-01-01

    Defluorination of graphite fluoride (CFX) by heating to temperatures of 250 to 450 C in chemically reactive environments was studied. This is a new and possibly inexpensive process to produce new carbon-based materials. For example, CF 0.68 fibers, made from P-100 carbon fibers, can be defluorinated in BrH2C-CH = CH-CH2Br (1,4-dibromo-2butene) heated to 370 C, and graphitized to produce fibers with an unusually high modulus and a graphite layer structure that is healed and cross-linked. Conversely, a sulfur-doped, visibly soft carbon fiber was produced by defluorinating CF 0.9 fibers, made from P-25, in sulfur (S) vapor at 370 C and then heating to 660 C in nitrogen (N2). Furthermore, defluorination of the CF 0.68 fibers in bromine (Br2) produced fragile, structurally damaged carbon fibers. Heating these fragile fibers to 1100 C in N2 caused further structural damage, whereas heating to 150 C in bromoform (CHBr3) and then to 1100 C in N2 healed the structural defects. The defluorination product of CFX, tentatively called activated graphite, has the composition and molecular structure of graphite, but is chemically more reactive. Activated graphite is a scavenger of manganese (Mn), and can be intercalated with magnesium (Mg). Also, it can easily collect large amounts of an alloy made from copper (Cu) and type 304 stainless steel to form a composite. Finally, there are indications that activated graphite can wet metals or ceramics, thereby forming stronger composites with them than the pristine carbon fibers can form.

  14. Process Optimization of Bismaleimide (BMI) Resin Infused Carbon Fiber Composite

    NASA Technical Reports Server (NTRS)

    Ehrlich, Joshua W.; Tate, LaNetra C.; Cox, Sarah B.; Taylor, Brian J.; Wright, M. Clara; Caraccio, Anne J.; Sampson, Jeffery W.

    2013-01-01

    Bismaleimide (BMI) resins are an attractive new addition to world-wide composite applications. This type of thermosetting polyimide provides several unique characteristics such as excellent physical property retention at elevated temperatures and in wet environments, constant electrical properties over a vast array of temperature settings, and nonflammability properties as well. This makes BMI a popular choice in advance composites and electronics applications [I]. Bismaleimide-2 (BMI-2) resin was used to infuse intermediate modulus 7 (IM7) based carbon fiber. Two panel configurations consisting of 4 plies with [+45deg, 90deg]2 and [0deg]4 orientations were fabricated. For tensile testing, a [90deg]4 configuration was tested by rotating the [0deg]4 configirration to lie orthogonal with the load direction of the test fixture. Curing of the BMI-2/IM7 system utilized an optimal infusion process which focused on the integration of the manufacturer-recommended ramp rates,. hold times, and cure temperatures. Completion of the cure cycle for the BMI-2/IM7 composite yielded a product with multiple surface voids determined through visual and metallographic observation. Although the curing cycle was the same for the three panellayups, the surface voids that remained within the material post-cure were different in abundance, shape, and size. For tensile testing, the [0deg]4 layup had a 19.9% and 21.7% greater average tensile strain performance compared to the [90deg]4 and [+45deg, 90deg, 90deg,-45degg] layups, respectively, at failure. For tensile stress performance, the [0deg]4 layup had a 5.8% and 34.0% greater average performance% than the [90deg]4 and [+45deg, 90deg, 90deg,-45deg] layups.

  15. Macroscopic fibers of well-aligned carbon nanotubes by wet spinning.

    PubMed

    Zhang, Shanju; Koziol, Krzysztof K K; Kinloch, Ian A; Windle, Alan H

    2008-08-01

    A simple process to spin fibers consisting of multi-walled carbon nanotubes (CNTs) directly from their lyotropic liquid-crystalline phase is reported. Ethylene glycol is used as the lyotropic solvent, enabling a wider range of CNT types to be spun than previously. Fibers spun with CNTs and nitrogen-doped CNTs are compared. X-ray analysis reveals that nitrogen-doped CNTs have a misalignment of only +/-7.8 degrees to the fiber axis. The tensile strength of the CNT and nitrogen-doped CNT fibers is comparable but the modulus and electrical conductivity of the are lower. The electrical conductivity of both types of CNT fibers is found to be highly anisotropic. The results are discussed in context of the microstructure of the CNTs and fibers. PMID:18666161

  16. Effect of acidification conditions on the properties of carbon nanotube fibers

    NASA Astrophysics Data System (ADS)

    Wang, Kun; Li, Min; Liu, Ya-Nan; Gu, Yizhuo; Li, Qingwen; Zhang, Zuoguang

    2014-02-01

    Carbon nanotube (CNT) fibers prepared by dry-spun method were functionalized by mixture of nitric and sulfuric acids. The effects of acidification conditions on the electrical conductivity and tensile properties of CNT fibers were investigated. A strong, high conductive CNT fiber was obtained under the optimal mixture ratio and processing time, with a electrical conductivity and tensile strength up to 3.2 × 104 S/m and 1103 MPa, respectively. It showed that the acids densified the surface of the CNT fiber and introduced functional groups onto the tubes, both of which contributed to the conductivity improvement of the CNT fiber. The infrared spectroscopy, Raman and fracture analysis indicated that acidification process resulted in two competitive effects on the tensile properties of CNT fibers, one was the positive contribution by the enhancement of interactions between CNTs through the densification and functional groups, and the other was the negative effect due to the structural destruction of the tubes.

  17. System to continuously produce carbon fiber via microwave assisted plasma processing

    DOEpatents

    White, Terry L; Paulauskas, Felix L; Bigelow, Timothy S

    2014-03-25

    A method for continuously processing carbon fiber including establishing a microwave plasma in a selected atmosphere contained in an elongated chamber having a microwave power gradient along its length defined by a lower microwave power at one end and a higher microwave power at the opposite end of the elongated chamber. The elongated chamber having an opening in each of the ends of the chamber that are adapted to allow the passage of the fiber tow while limiting incidental gas flow into or out of said chamber. A continuous fiber tow is introduced into the end of the chamber having the lower microwave power. The fiber tow is withdrawn from the opposite end of the chamber having the higher microwave power. The fiber to is subjected to progressively higher microwave energy as the fiber is being traversed through the elongated chamber.

  18. Widely tunable mode-locked fiber laser using carbon nanotube and LPG W-shaped filter.

    PubMed

    Wang, Jie; Zhang, A Ping; Shen, Yong Hang; Tam, Hwa-yaw; Wai, P K A

    2015-09-15

    A widely tunable mode-locked fiber laser using a carbon nanotube absorber and a fiber-optic W-shaped spectral filter is presented. The W-shaped filter is constructed by sandwiching a phase-shifted long-period grating between two LPGs of different periods. By adjusting the temperature of the W-shaped filter from 23°C to 100°C, the central wavelength of the mode-locked fiber laser can be continuously tuned from 1597 to 1553 nm. The tuning range is further extended to 1531.6 nm when a shorter erbium-doped fiber is used in the fiber oscillator. The experimental results reveal that the large thermal tunability of the proposed LPG filter provides an effective approach to achieve compact widely tunable mode-locked fiber lasers covering both C and L bands.

  19. Pyrolysis Pathways of Sulfonated Polyethylene, an Alternative Carbon Fiber Precursor

    SciTech Connect

    Younker, Jarod M; Saito, Tomonori; Hunt, Marcus A; Beste, Ariana; Naskar, Amit K

    2013-01-01

    Sulfonated polyethylene is an emerging precursor for the production of carbon fibers. Pyrolysis of sulfonated polyethylene was characterized by thermogravimetric analysis (TGA). n-heptane-4-sulfonic acid (H4S) was selected as a model compound for the study of sulfonated polyethylene. Density functional theory and conventional transition state theory were used to determine the rate constants of pyrolysis for H4S from 300-1000 K. Multiple reaction channels from two different mechanisms were explored: 1) internal five-centered elimination (Ei 5) and 2) radical chain reaction. The pyrolysis of H4S was simulated with kinetic Monte Carlo (kMC) to obtain TGA plots that compared favorably to experiment. We observed that at tem- peratures < 550 K, the radical mechanism was dominant and yielded the trans-alkene, whereas cis-alkene was formed at higher temperatures from the internal elimination. The maximum rates of % mass loss became independent of initial OH radical concentration at 440-480 K. Experimentally, the maximum % mass loss occurred from 440-460 K (heating rate dependent). Activation energies derived from the kMC-simulated TGAs of H4S (26-29 kcal/mol) agreed with experiment for sulfonated polyethylene ( 31 kcal/mol). The simulations revealed that in this region, decomposition of radical HOSO2 became competitive to H abstraction by HOSO2, making OH the carrying radical for the reaction chain. The maximum rate of % mass loss for internal elimination was observed at temperatures > 600 K. Low-scale carbonization utilizes temperatures < 620 K; thus, internal elimination will not be competitive. Ei5 elimination has been studied for sulfoxides and sulfones, but this represents the first study of internal elimination in sulfonic acids. Nonlinear Arrhenius plots were found for all bimolecular reactions. The most significant nonlinear behavior was observed for reactions where the barrier was small. For reactions with low activation barriers, nonlinearity was traced to

  20. Sulfur-impregnated activated carbon fiber cloth as a binder-free cathode for rechargeable Li-S batteries.

    PubMed

    Elazari, Ran; Salitra, Gregory; Garsuch, Arnd; Panchenko, Alexander; Aurbach, Doron

    2011-12-15

    A route for the preparation of binder-free sulfur-carbon cathodes is developed for lithium sulfur batteries. The method is based on the impregnation of elemental sulfur into the micropores of activated carbon fibers. These electrodes demonstrate good electrochemical performance at high current density attributed to the uniform dispersion of sulfur inside the carbon fiber. PMID:22052740

  1. Improvement of fatigue life and prevention of internal crack initiation of chopped carbon fiber reinforced plastics modified with micro glass fibers

    NASA Astrophysics Data System (ADS)

    Fujitani, Ryohei; Okubo, Kazuya; Fujii, Toru

    2016-04-01

    The purpose of this study is to improve fatigue properties of chopped carbon fiber reinforced plastics fabricated by SMC (Sheet Molding Compound) method and to clarify the mechanism for improvement. To enhance the properties, micro glass fibers with 500nm in diameter were added directly into vinyl ester resin with 0.3wt% contents. The chopped carbon fiber reinforced plastics were fabricated and cured at room temperature for 1hour under 1MPa and then at 60degree-C for 3hours. After curing, the fabricated plate was cut into the dimension of specimen. Tensile and bending strength and fatigue life of chopped carbon fiber reinforced plastics were investigated by tensile and three point bending test and cyclic tension-tension test, respectively. The behavior of strain concentration around the tips of carbon fiber were discussed with model specimen on the observations with DIC (Digital Image Correlation) method and polarizing microscope under tensile loading, in which one chopped carbon fiber was embedded into the matrix. In conclusion, when toughened vinyl ester resin modified with micro glass fibers was used as matrix, tensile and bending strength and fatigue life of chopped carbon fiber reinforced plastics were increased 56.6%, 49.8% and 14 to 23 times compared with those of unmodified specimens. It should be explained that static and dynamic properties of chopped carbon fiber reinforced plastics were improved by that crack initiation and propagation were prevented according to the prevention of the locally increasing of strain around the tip of carbon fiber, when vinyl ester resin modified with micro glass fibers was used as matrix.

  2. Continuous Carbon Nanotube-Based Fibers and Films for Applications Requiring Enhanced Heat Dissipation.

    PubMed

    Liu, Peng; Fan, Zeng; Mikhalchan, Anastasiia; Tran, Thang Q; Jewell, Daniel; Duong, Hai M; Marconnet, Amy M

    2016-07-13

    The production of continuous carbon nanotube (CNT) fibers and films has paved the way to leverage the superior properties of individual carbon nanotubes for novel macroscale applications such as electronic cables and multifunctional composites. In this manuscript, we synthesize fibers and films from CNT aerogels that are continuously grown by floating catalyst chemical vapor deposition (FCCVD) and measure thermal conductivity and natural convective heat transfer coefficient from the fiber and film. To probe the mechanisms of heat transfer, we develop a new, robust, steady-state thermal characterization technique that enables measurement of the intrinsic fiber thermal conductivity and the convective heat transfer coefficient from the fiber to the surrounding air. The thermal conductivity of the as-prepared fiber ranges from 4.7 ± 0.3 to 28.0 ± 2.4 W m(-1) K(-1) and depends on fiber volume fraction and diameter. A simple nitric acid treatment increases the thermal conductivity by as much as a factor of ∼3 for the fibers and ∼6.7 for the thin films. These acid-treated CNT materials demonstrate specific thermal conductivities significantly higher than common metals with the same absolute thermal conductivity, which means they are comparatively lightweight, thermally conductive fibers and films. Beyond thermal conductivity, the acid treatment enhances electrical conductivity by a factor of ∼2.3. Further, the measured convective heat transfer coefficients range from 25 to 200 W m(-2) K(-1) for all fibers, which is higher than expected for macroscale materials and demonstrates the impact of the nanoscale CNT features on convective heat losses from the fibers. The measured thermal and electrical performance demonstrates the promise for using these fibers and films in macroscale applications requiring effective heat dissipation. PMID:27322344

  3. Effects of carbon fiber surface characteristics on interfacial bonding of epoxy resin composite subjected to hygrothermal treatments

    NASA Astrophysics Data System (ADS)

    Li, Min; Liu, Hongxin; Gu, Yizhuo; Li, Yanxia; Zhang, Zuoguang

    2014-01-01

    The changes of interfacial bonding of three types of carbon fibers/epoxy resin composite as well as their corresponding desized carbon fiber composites subjecting to hygrothermal conditions were investigated by means of single fiber fragmentation test. The interfacial fracture energy was obtained to evaluate the interfacial bonding before and after boiling water aging. The surface characteristics of the studied carbon fiber were characterized using X-ray photoelectron spectroscopy. The effects of activated carbon atoms and silicon element at carbon fiber surface on the interfacial hygrothermal resistance were further discussed. The results show that the three carbon fiber composites with the same resin matrix possess different hygrothermal resistances of interface and the interfacial fracture energy after water aging can not recovery to the level of raw dry sample (irreversible changes) for the carbon fiber composites containing silicon. Furthermore, the activated carbon atoms have little impact on the interfacial hygrothermal resistance. The irreversible variations of interfacial bonding and the differences among different carbon fiber composites are attributed to the silicon element on the carbon fiber bodies, which might result in hydrolyzation in boiling water treatment and degrade interfacial hygrothermal resistance.

  4. Uptake of atmospheric carbon dioxide into silk fiber by silkworms.

    PubMed

    Magoshi, Jun; Tanaka, Toshihisa; Sasaki, Haruto; Kobayashi, Masatoshi; Magoshi, Yoshiko; Tsuda, Hidetoshi; Becker, Mary A; Inoue, Shun-ichi; Ishimaru, Ken

    2003-01-01

    The relation between the uptake of atmospheric CO(2) and insect's production of silk fiber has not yet been reported. Here, we provide the first quantitative demonstrations that four species of silkworms (Bombyx mori, Samia cynthia ricini, Antheraea pernyi, and Antheraea yamamai) and a silk-producing spider (Nephila clavata) incorporate atmospheric CO(2) into their silk fibers. The abundance of (13)C incorporated from the environment was determined by mass spectrometry and (13)C NMR measurements. Atmospheric CO(2) was incorporated into the silk fibers in the carbonyl groups of alanine, aspartic acid, serine, and glycine and the C(gamma) of aspartic acid. We show a simple model for the uptake of atmospheric CO(2) by silkworms. These results will demonstrate that silkworm has incorporated atmospheric CO(2) into silk fiber via the TCA cycle; however, the magnitude of uptake into the silk fibers is smaller than that consumed by the photosynthesis in trees and coral reefs.

  5. Surface structural evolvement in the conversion of polyacrylonitrile precursors to carbon fibers

    NASA Astrophysics Data System (ADS)

    Qian, Xin; Zou, Ruifen; OuYang, Qin; Wang, Xuefei; Zhang, Yonggang

    2015-02-01

    Surface structural evolvement in the conversion of polyacrylonitrile (PAN) precursors to carbon fibers was investigated through scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). SEM results showed that the characteristic striated topography of PAN precursors resulted from the wet spinning process could pass down to carbon fibers. The fiber diameter gradually decreased from 11.3 μm to 5.5 μm and the corresponding density increased from 1.18 g/cm3 to 1.80 g/cm3 in the conversion of PAN precursors to carbon fibers. The ridges and grooves monitored by AFM became much more well-defined after the thermo-oxidation. However, the original longitudinal grooves were destroyed and both the depth and the width of longitudinal grooves decreased after the carbonization. XPS results revealed that carbon, nitrogen, oxygen and silicon were the governing elements on the fiber surface. The sbnd Csbnd C functional groups was the dominant groups and the relative contents of sbnd Cdbnd O and sbnd COO groups gradually increased in the process of thermo-oxidation and carbonization.

  6. Fiber

    MedlinePlus

    ... it can help with weight control. Fiber aids digestion and helps prevent constipation . It is sometimes used ... fiber attracts water and turns to gel during digestion. This slows digestion. Soluble fiber is found in ...

  7. Properties of M40J Carbon/PMR-II-50 Composites Fabricated with Desized and Surface Treated Fibers. Characterization of M40J Desized and Finished Fibers

    NASA Technical Reports Server (NTRS)

    Allred, Ronald E.; Gosau, Jan M.; Shin, E. Eugene; McCorkle, Linda S.; Sutter, James K.; OMalley, Michelle; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    To increase performance and durability of high temperature composites for potential rocket engine components, it is necessary to optimize wetting and interfacial bonding between high modulus carbon fibers and high temperature polyimide resins. It has been previously demonstrated that the electro-oxidative shear treatments used by fiber manufacturers are not effective on higher modulus fibers that have fewer edge and defect sites in the surface crystallites. In addition, sizings commercially supplied on most carbon fibers are not compatible with polyimides. This study was an extension of prior work characterizing the surface chemistry and energy of high modulus carbon fibers (M40J and M60J, Torray) with typical fluorinated polyimide resins, such as PMR-II-50. A continuous desizing system which utilizes environmentally friendly chemical- mechanical processes was developed for tow level fiber and the processes were optimized based on weight loss behavior, surface elemental composition (XPS) and morphology (FE-SEM) analyses, and residual tow strength of the fiber, and the similar approaches have been applied on carbon fabrics. Both desized and further treated with a reactive finish were investigated for the composite reinforcement. The effects of desizing and/or subsequent surface retreatment on carbon fiber on composite properties and performance including fiber-matrix interfacial mechanical properties, thermal properties and blistering onset behavior will be discussed in this presentation.

  8. Strain-rate dependence of the compressive properties of normal and carbon-fiber-reinforced bone cement.

    PubMed

    Saha, S; Pal, S

    1983-11-01

    Normal and carbon-fiber-reinforced (1 wt. %) bone cement samples were tested in compression at various strain rates. Both the compressive strength and proportional limit increased in general with increasing strain rate. Similar strain-rate sensitivity was also shown by the carbon-fiber-reinforced bone cement. The mechanical properties, namely the modulus of elasticity, the proportional limit, and the compressive strength of the carbon-fiber-reinforced bone cement showed highly significant positive correlations with the strain rate. PMID:6654926

  9. Carbon Nanotubes and Carbon Nanotube Fiber Sensors: Growth, Processing and Characterization

    NASA Astrophysics Data System (ADS)

    Zhao, Haibo

    With multiple outstanding properties, such as high Young's modulus, high strength, good thermal conductivity and electrical conductivity, carbon nanotube (CNT) has been considered as a new generation of material that has many potential applications in many fields. One obstacle that stands in the way of applying CNTs in the real world is the limited growth length. Catalyst instability is one of the many factors that cause the stops of CNT growth. In this research, intermetalic Fe-Zr catalyst was used to grow millimeter long CNT arrays. The Fe-Zr particles enabled the growth of 1.7 millimeter long carbon nanotube arrays in 45 minutes. A comparison with pure Fe catalyst indicated that adding Zr to iron can stabilize the Fe catalyst at the CNT growth temperature and moderate its reactivity. In future, when CNTs are largely used in industrial, mass production of CNTs at a low cost is vital for market competition. In many current CNT growth methods, a process of depositing a thin catalyst film on top of Al 2O3 film on a piece of silicon wafer is required. Thus the size of CNT samples is limited by the size of the largest silicon wafer currently available, which is 8 inch in diameter. In this study, FeCl2 powders were used as the catalyst to grow CNT arrays not only on traditional silicon substrates but also on quartz substrates and carbon sheets. This unique method does not require the thin film deposition step, which shortens the time used for each batch of CNT growth. The simplicity of this method allows an easy scale-up for mass production of CNTs with a low cost. In order to improve this method, HCl was used to assist the CNT growth. HCl was added via flowing a small amount of C2H2 thorough a bubbuler where HCl solution was contained. With the assistance of HCl, CNT growth could be extended to 1 hour. 3 mm tall non-spinnable arrays and 2 mm tall spinnable arrays were produced using this method. With the increasing use of composite materials, real time health

  10. Oxidation Kinetics and Strength Degradation of Carbon Fibers in a Cracked Ceramic Matrix Composite

    NASA Technical Reports Server (NTRS)

    Halbig, Michael C.

    2003-01-01

    Experimental results and oxidation modeling will be presented to discuss carbon fiber susceptibility to oxidation, the oxidation kinetics regimes and composite strength degradation and failure due to oxidation. Thermogravimetric Analysis (TGA) was used to study the oxidation rates of carbon fiber and of a pyro-carbon interphase. The analysis was used to separately obtain activation energies for the carbon constituents within a C/SiC composite. TGA was also conducted on C/SiC composite material to study carbon oxidation and crack closure as a function of temperature. In order to more closely match applications conditions C/SiC tensile coupons were also tested under stressed oxidation conditions. The stressed oxidation tests show that C/SiC is much more susceptible to oxidation when the material is under an applied load where the cracks are open and allow for oxygen ingress. The results help correlate carbon oxidation with composite strength reduction and failure.

  11. Anodization of carbon fibers on interfacial mechanical properties of epoxy matrix composites.

    PubMed

    Park, Soo-Jin; Chang, Yong-Hwan; Kim, Yeong-Cheol; Rhee, Kyong-Yop

    2010-01-01

    The influence of anodic oxidation on the mechanical interfacial properties of carbon-fiber-reinforced epoxy resin composites was investigated. The surface properties of the anodized carbon fibers were studied through the measurement of contact angles and through SEM, XPS, and FT-IR analyses. The mechanical interfacial properties of the composites were studied through measurements of interlaminar shear strength (ILSS), critical stress intensity factor (K(IC)), and critical strain energy release rate (G(IC)). It was shown that the surface functional groups containing oxygen on the anodized carbon fibers exert great effects on the surface energetics of fibers and the mechanical interfacial properties, e.g., ILSS, of the resulting composites. Contact angle measurements based on the wicking rate of a test liquid showed that anodic oxidation lead to an increase in the surface free energy of the carbon fibers, mainly in its specific (or polar) component. In terms of surface energetics, it was found that wetting played an important role in increasing the degree of adhesion at interfaces between the fibers and the resin matrices of the composites. PMID:20352820

  12. Surface Characterization of Carbon Fiber Polymer Composites and Aluminum Alloys After Laser Interference Structuring

    NASA Astrophysics Data System (ADS)

    Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian; Warren, Charles D.; Daniel, Claus

    2016-07-01

    The increasing use of carbon fiber-reinforced polymer matrix composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (1) structuring of the AL 5182 surface, (2) removal of the resin layer on top of carbon fibers, and (3) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg—T83 epoxy, 5 ply thick, 0°/90° plaques were used. The effects of laser fluence, scanning speed, and number of shots-per-spot were investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope imaging were used to study the effect of the laser processing on the surface morphology. It was found that an effective resin ablation and a low density of broken fibers for CFPC specimens was attained using laser fluences of 1-2 J/cm2 and number of 2-4 pulses per spot. A relatively large area of periodic line structures due to energy interference were formed on the aluminum surface at laser fluences of 12 J/cm2 and number of 4-6 pulses per spot.

  13. Stability of nickel coatings on carbon fiber preforms: A SEM investigation

    NASA Astrophysics Data System (ADS)

    Carotenuto, G.; Gallo, A.; Nicolais, L.

    1994-05-01

    Metal Matrix Composites (MMC's) reinforced with continuous fibers were generally fabricated by a foil-sandwich technique or by liquid metal infiltration. Liquid metal infiltration may be used to cast final shapes in molds containing fiber preforms. It is also used to make composite wire from which may be fabricated panels and shapes by hot-press diffusion bonding or pultrusion. The major drawback of this method is that the molten matrix must wet the fiber for successful infiltration to occur, requiring special fiber surface treatments or matrix additives, and that, molten metals generally dissolve or degrade the fibers, necessitating a barrier coating on the fibers. All these problems can be solved using carbon fibers coated with metallic layers, e.g. nickel. This work analyses an easy method to produce modified carbon fibers by electroplating and the process of its recristallization. The topography of the growth front of the deposit has been studied. At temperatures higher than about 300° C an annealing under vacuum is required, because of the high reactivity of metal coating, nevertheless the heat treatment of metal deposit produces always an embrittled material.

  14. Production of vapor grown carbon fiber with coal fines without SO{sub 2} emissions

    SciTech Connect

    Burton, D.; Lake, M.; Alig, R.

    1996-12-31

    Each year millions of tons of low-cost hydrocarbons in the form of coal fines are impounded. One potential application would be utilization in a unique process capable of converting the carbon into a highly graphitic vapor-grown carbon fiber (VGCF). This process currently produces vapor-grown carbon fiber from the vapor phase using natural gas, hydrogen sulfide and iron particles. The iron particles initiate the growth of the carbon fibers while the hydrogen sulfide enhances the yield, allowing the process to be economically feasible. Previous demonstrations involving pulverized coal have proven that coal can be used as an alternative source of carbon and sulfur in the production of VGCF. Furthermore, there is evidence that the sulfur from the coal remains with the carbon fiber catalyst during the reaction and does not exhaust as SO{sub 2} into the atmosphere. It is the object of this research to determine if coal fines pulverized to -325 mesh are also a viable source of carbon and sulfur for VGCF production.

  15. Carbon fibers: Thermochemical recovery from advanced composite materials and activation to an adsorbent

    NASA Astrophysics Data System (ADS)

    Staley, Todd Andrew

    This research addresses an expanding waste disposal problem brought about by the increasing use of advanced composite materials, and the lack of technically and environmentally viable recycling methods for these materials. A thermochemical treatment process was developed and optimized for the recycling of advanced composite materials. Counter-current gasification was employed for the treatment of carbon fiber reinforced-epoxy resin composite wastes. These materials were treated, allowing the reclamation of the material's valuable components. As expected in gasification, the organic portion of the waste was thermochemically converted to a combustible gas with small amounts of organic compounds that were identified by GC/MS. These compounds were expected based on data in the literature. The composites contain 70% fiber reinforcement, and gasification yielded approximately 70% recovered fibers, representing nearly complete recovery of fibers from the waste. Through SEM and mechanical testing, the recovered carbon fibers were found to be structurally and mechanically intact, and amenable to re-use in a variety of applications, some of which were identified and tested. In addition, an application was developed for the carbon fiber component of the waste, as an activated carbon fiber adsorbent for the treatment of wastewaters. This novel class of adsorbent was found to have adsorption rates, for various organic molecules, up to a factor of ten times those of commercial granular activated carbon, and adsorption capacities similar to conventional activated carbons. Overall, the research addresses an existing environmental waste problem, employing a thermochemical technique to recycle and reclaim the waste. Components of the reclaimed waste material are then employed, after further modification, to address other existing and potential environmental waste problems.

  16. Friction Behaviour of Polymeric Composite Materials Mixed with Carbon Fibers Having Different Orientations Layout

    NASA Astrophysics Data System (ADS)

    Caliman, R.

    2016-06-01

    This paper presents a study of the friction properties of polymeric composite materials reinforced with unidirectional carbon fibers having different stratified structure. So, the composites are complex and versatile materials but their behaviour in practice is not fully studied. For instance, these polymeric composite materials mixed with carbon fibers after being investigated in terms of wear, did not elucidate the effect of fiber orientation on wear properties. Is therefore necessary to investigate the effect of carbon fibers orientation on the friction-wear properties of the reinforced composite materials tested to abrasive and adhesive friction. Research work has been done with unidirectional composite materials having overlap 18 successive layers made from a polymeric resine and 60% of carbon fibers. The stratified structure was obtained by compressing multiple pre-impregnated strips, positioned manually. During this experimental work, three types of test samples were investigated: parallel, normal and anti-parallel, taking in consideration the carbon fibre orientation with respect to the sliding direction. The friction coefficient is computed function to the friction load and loading value. Also, the specific wear rate was calculated according to: the mass loss, density, the normal contact surface, the sliding distance and load rating.

  17. RTA-treated carbon fiber/copper core/shell hybrid for thermally conductive composites.

    PubMed

    Yu, Seunggun; Park, Bo-In; Park, Cheolmin; Hong, Soon Man; Han, Tae Hee; Koo, Chong Min

    2014-05-28

    In this paper, we demonstrate a facile route to produce epoxy/carbon fiber composites providing continuous heat conduction pathway of Cu with a high degree of crystal perfection via electroplating, followed by rapid thermal annealing (RTA) treatment and compression molding. Copper shells on carbon fibers were coated through electroplating method and post-treated via RTA technique to reduce the degree of imperfection in the Cu crystal. The epoxy/Cu-plated carbon fiber composites with Cu shell of 12.0 vol % prepared via simple compression molding, revealed 18 times larger thermal conductivity (47.2 W m(-1) K(-1)) in parallel direction and 6 times larger thermal conductivity (3.9 W m(-1) K(-1)) in perpendicular direction than epoxy/carbon fiber composite. Our novel composites with RTA-treated carbon fiber/Cu core/shell hybrid showed heat conduction behavior of an excellent polymeric composite thermal conductor with continuous heat conduction pathway, comparable to theoretical values obtained from Hatta and Taya model.

  18. Recent Progress in Producing Lignin-Based Carbon Fibers for Functional Applications

    SciTech Connect

    Paul, Ryan; Burwell, Deanna; Dai, Xuliang; Naskar, Amit; Gallego, Nidia; Akato, Kokouvi

    2015-10-29

    Lignin, a biopolymer, has been investigated as a renewable and low-cost carbon fiber precursor since the 1960s. Although successful lab-scale production of lignin-based carbon fibers has been reported, there are currently not any commercial producers. This paper will highlight some of the known challenges with converting lignin-based precursors into carbon fiber, and the reported methods for purifying and modifying lignin to improve it as a precursor. Several of the challenges with lignin are related to its diversity in chemical structure and purity, depending on its biomass source (e.g. hardwood, softwood, grasses) and extraction method (e.g. organosolv, kraft). In order to make progress in this field, GrafTech and Oak Ridge National Laboratory are collaborating to develop lignin-based carbon fiber technology and to demonstrate it in functional applications, as part of a cooperative agreement with the DOE Advanced Manufacturing Office. The progress made to date with producing lignin-based carbon fiber for functional applications, as well as developing and qualifying a supply chain and value proposition, are also highlighted.

  19. Electrospun carbon nanofibers for improved electrical conductivity of fiber reinforced composites

    NASA Astrophysics Data System (ADS)

    Alarifi, Ibrahim M.; Alharbi, Abdulaziz; Khan, Waseem S.; Asmatulu, Ramazan

    2015-04-01

    Polyacrylonitrile (PAN) was dissolved in dimethylformamide (DMF), and then electrospun to generate nanofibers using various electrospinning conditions, such as pump speeds, DC voltages and tip-to-collector distances. The produced nanofibers were oxidized at 270 °C for 1 hr, and then carbonized at 850 °C in an argon gas for additional 1 hr. The resultant carbonized PAN nanofibers were placed on top of the pre-preg carbon fiber composites as top layers prior to the vacuum oven curing following the pre-preg composite curing procedures. The major purpose of this study is to determine if the carbonized nanofibers on the fiber reinforced composites can detect the structural defects on the composite, which may be useful for the structural health monitoring (SHM) of the composites. Scanning electron microscopy images showed that the electrospun PAN fibers were well integrated on the pre-preg composites. Electrical conductivity studies under various tensile loads revealed that nanoscale carbon fibers on the fiber reinforced composites detected small changes of loads by changing the resistance values. Electrically conductive composite manufacturing can have huge benefits over the conventional composites primarily used for the military and civilian aircraft and wind turbine blades.

  20. Electrodeposited manganese dioxide nanostructures on electro-etched carbon fibers: High performance materials for supercapacitor applications

    SciTech Connect

    Kazemi, Sayed Habib; Maghami, Mostafa Ghaem; Kiani, Mohammad Ali

    2014-12-15

    Highlights: • We report a facile method for fabrication of MnO{sub 2} nanostructures on electro-etched carbon fiber. • MnO{sub 2}-ECF electrode shows outstanding supercapacitive behavior even at high discharge rates. • Exceptional cycle stability was achieved for MnO{sub 2}-ECF electrode. • The coulombic efficiency of MnO{sub 2}-ECF electrode is nearly 100%. - Abstract: In this article we introduce a facile, low cost and additive/template free method to fabricate high-rate electrochemical capacitors. Manganese oxide nanostructures were electrodeposited on electro-etched carbon fiber substrate by applying a constant anodic current. Nanostructured MnO{sub 2} on electro-etched carbon fiber was characterized by scanning electron microscopy, X-ray diffraction and energy dispersive X-ray analysis. The electrochemical behavior of MnO{sub 2} electro-etched carbon fiber electrode was investigated by electrochemical techniques including cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. A maximum specific capacitance of 728.5 F g{sup −1} was achieved at a scan rate of 5 mV s{sup −1} for MnO{sub 2} electro-etched carbon fiber electrode. Also, this electrode showed exceptional cycle stability, suggesting that it can be considered as a good candidate for supercapacitor electrodes.

  1. Activation and micropore structure determination of activated carbon-fiber composites

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.; Kimber, G.

    1997-09-05

    Rigid, high surface area activated carbon fiber composites have been produced with high permeabilities for environmental applications in gas and water purification. These novel monolithic adsorbents can be produced in single pieces to a given size and shape. The project involves a collaboration between the Oak Ridge National Laboratory (ORNL) and the Center for Applied Energy Research (CAER), University of Kentucky. The carbon fiber composites are produced at the ORNL and activated at the CAER using different methods, with the aims of producing a uniform degree of activation, and of closely controlling pore structure and adsorptive properties. The main focus of the present work has been to find a satisfactory means to uniformly activate large samples of carbon fiber composites and produce controlled pore structures. Several environmental applications have been explored for the activated carbon fiber composites. One of these was to evaluate the activated composites for the separation of CH{sub 4}-CO{sub 2} mixtures, and an apparatus was constructed specifically for this purpose. The composites were further evaluated in the cyclic recovery of volatile organics. The activated carbon fiber composites have also been tested for possible water treatment applications by studying the adsorption of sodium pentachlorophenolate, PCP.

  2. Improvement of discharge characteristics of latent heat thermal energy storage unit by using carbon fibers

    SciTech Connect

    Fukai, Jun; Oishi, Akira; Kodama, Yoshikazu; Kanou, Makoto; Miyatake, Osamu

    1999-07-01

    Many phase change materials have unacceptably low thermal conductivities. Metal fins, metal honeycombs and metal matrices have been examined to enhance the thermal conductivity of the PCMs. This study proposed an enhancement technique using carbon fibers with high thermal conductivity. The thermal conductivity of the carbon fibers prepared in this study is 220 W/(m{center_dot}K). Paraffin wax (0.26 W/(m{center_dot}K) in solid phase) and Na{sub 2}SO{sub 4}{center_dot}10H{sub 2}O-mixture (0.8 W/(m{center_dot}K) in solid phase) were selected as heat storage media. The fibers were uniformly mixed with th PCM encapsulated in a cylindrical capsule. The effective thermal conductivities of the fibers/PCM composites were measured. Figure A-1 shows the ratio of the effective thermal conductivity of the composite (k{sub c}) to the thermal conductivity of the phase change material (k{sub m}). The figure demonstrates that the fibers essentially enhance the thermal conductivities of paraffin. For paraffin, there is little dependence of the effective thermal conductivity on the fiber length (L{sub f}). Though the k{sub c}/k{sub m} for Na{sub 2}SO{sub 4}{center_dot}10H{sub 2}O-mixture is lower than that of the paraffin wax, 2% fibers increase the thermal conductivity of the PCM by a factor of about three. This value is almost identical to the thermal conductivity of ice (2.2 W/(m{center_dot}K)). The effect of the carbon fibers on discharge characteristics of a thermal energy storage system was investigated. Capsules containing a carbon fibers/paraffin composite are packed into a thermal energy storage unit. The inlet fluid temperature (T{sub in})and the outlet fluid temperature (T{sub out}) were measured during the discharge process. Figure A-2 shows a typical result of the experiments. Remarkable effect of the fibers is observed after the outlet temperature reaches the phase change temperature ({approx}60 C). That is, the period where the outlet temperature is maintained near the

  3. Adsorption of SO2 on bituminous coal char and activated carbon fiber prepared from phenol formaldehyde

    USGS Publications Warehouse

    DeBarr, Joseph A.; Lizzio, Anthony A.; Daley, Michael A.

    1996-01-01

    Carbon-based materials are used commercially to remove SO2 from coal combustion flue gases. Historically, these materials have consisted of granular activated carbons prepared from lignite or bituminous coal. Recent studies have reported that activated carbon fibers (ACFs) may have potential in this application due to their relatively high SO2 adsorption capacity. In this paper, a comparison of SO2 adsorption for both coal-based carbons and ACFs is presented, as well as ideas on carbon properties that may influence SO2 adsorption

  4. Morphology dependent field emission of acid-spun carbon nanotube fibers.

    PubMed

    Fairchild, S B; Boeckl, J; Back, T C; Ferguson, J B; Koerner, H; Murray, P T; Maruyama, B; Lange, M A; Cahay, M M; Behabtu, N; Young, C C; Pasquali, M; Lockwood, N P; Averett, K L; Gruen, G; Tsentalovich, D E

    2015-03-13

    Acid spun carbon nanotube (CNT) fibers were investigated for their field emission properties and performance was determined to be dependent on fiber morphology. The fibers were fabricated by wet-spinning of pre-made CNTs. Fiber morphology was controlled by a fabrication method and processing conditions, as well as purity, size, and type of the CNT starting material. The internal fiber structure consisted of CNT fibrils held together by van der Waals forces. Alignment and packing density of the CNTs affects the fiber's electrical and thermal conductivity. Fibers with similar diameters and differing morphology were compared, and those composed of the most densely packed and well aligned CNTs were the best field emitters as exhibited by a lower turn-on voltage and a larger field enhancement factor. Fibers with higher electrical and thermal conductivity demonstrated higher maximum current before failure and longer lifetimes. A stable emission current at 3 mA was obtained for 10 h at a field strength of <1 V μm(-1). This stable high current operation makes these CNT fibers excellent candidates for use as low voltage electron sources for vacuum electronic devices. PMID:25694166

  5. The influence of surface properties on carbon fiber/epoxy matrix interfacial adhesion

    SciTech Connect

    Zhuang, H.; Wightman, J.P.

    1996-12-31

    In recent years, as composites become increasingly sophisticated to meet ever-increasing performance requirements, it has become more important to control the interaction between the reinforcing fibers and matrix materials. The major challenge here is the lack of fundamental understanding and knowledge about the reinforcement/matrix system which contribute to the establishment of the interphase. It has been recognized that the state of the fiber surface substantially effects the quality of interfacial adhesion. However, basic and specific correlation is still incomplete. The possible mechanisms by which the fiber surface parameters contribute to the constitution of the fiber/matrix interface include the interfacial chemical and physical interactions caused by fiber surface functionality and surface energy, the mechanical interlocking due to fiber surface irregularity, and, the interfacial wetting based on fiber surface energy. It was the objective of this work to explore the effects of physical and chemical aspects of fiber surfaces on the durability of interfacial adhesion in carbon fiber reinforced composites.

  6. Basic failure mechanisms in advanced composites. [composed of epoxy resins reinforced with carbon fibers

    NASA Technical Reports Server (NTRS)

    Mazzio, V. F.; Mehan, R. L.; Mullin, J. V.

    1973-01-01

    The fundamental failure mechanisms which result from the interaction of thermal cycling and mechanical loading of carbon-epoxy composites were studied. This work was confined to epoxy resin uniderictionally reinforced with HTS carbon fibers, and consists of first identifying local fiber, matrix and interface failure mechanisms using the model composite specimen containing a small number of fibers so that optical techniques can be used for characterization. After the local fracture process has been established for both mechanical loading and thermal cycling, engineering composite properties and gross fracture modes are then examined to determine how the local events contribute to real composite performance. Flexural strength in high fiber content specimens shows an increase in strength with increased thermal cycling. Similar behavior is noted for 25 v/o material up to 200 cycles; however, there is a drastic reduction after 200 cycles indicating a major loss of integrity probably through the accumulation of local cleavage cracks in the tensile region.

  7. Ribbon-to-fiber transformation in the process of spinning of carbon-nanotube dispersion.

    PubMed

    Kornev, Konstantin G; Callegari, Gerardo; Kuppler, John; Ruetsch, Sigrid; Neimark, Alexander V

    2006-11-01

    We describe a phenomenon of ribbon-to-fiber transformation observed in the process of spinning of single wall carbon nanotubes dispersed in polymer solutions. In the process of spinning, a gel-like ribbon comprised of nanotube bundles bound by polymer is withdrawn from a solvent bath. We show that upon crossing the liquid-air interface, the ribbon may either retain its flat shape or fold into a compact hairlike fiber. The ribbon-to-fiber transformation is caused by the capillary action of the liquid meniscus embracing the ribbon. Only sufficiently stiff ribbons can withhold the capillary compression. The critical conditions of folding, as well as the number of folds in the contractive ribbon, depend on the ribbon width, its flexural rigidity, and the solvent surface tension. We show that the ribbon rigidity can be efficiently modulated by varying the solvent composition, allowing us to control the pore structure of carbon-nanotube fibers. PMID:17155588

  8. Synthesis of Meltspun Multiwall Carbon Nanotube/Polycarbonate Fibers Through Solvent Casting and Melt Extrusion.

    PubMed

    Yadav, Poonam; Park, Sang Whan; Lee, Dong Bok

    2015-11-01

    Films and strands consisting of polycarbonate (PC) containing 0.55 or 0.75 wt% multiwall carbon nanotubes (MWNTs) were synthesized through solvent casting and melt extrusion methods, respectively. They were further processed into fibers through melt spinning. Fibers made from melt-extruded strands exhibited a smoother surface, more uniform morphology, and better dispersion of MWNTs in PC than those made from solvent-cast films. PMID:26726657

  9. Synthesis of Meltspun Multiwall Carbon Nanotube/Polycarbonate Fibers Through Solvent Casting and Melt Extrusion.

    PubMed

    Yadav, Poonam; Park, Sang Whan; Lee, Dong Bok

    2015-11-01

    Films and strands consisting of polycarbonate (PC) containing 0.55 or 0.75 wt% multiwall carbon nanotubes (MWNTs) were synthesized through solvent casting and melt extrusion methods, respectively. They were further processed into fibers through melt spinning. Fibers made from melt-extruded strands exhibited a smoother surface, more uniform morphology, and better dispersion of MWNTs in PC than those made from solvent-cast films.

  10. NDT and SHM of Carbon Fiber Composites using Linear Drive MWM-Arrays

    NASA Technical Reports Server (NTRS)

    Washabaugh, Andrew; Martin, Christopher; Lyons, Robert; Grundy, David; Goldfine, Neil; Russell, Richard; Wincheski, Russell

    2012-01-01

    Carbon fiber composites are used in a wide range of structural applications due to their excellent specific strength and stiffness. However, the anisotropic mechanical and electrical properties associated with the fibers within each composite layer present challenges, and opportunities, for Nondestructive Testing (NDT) methods used to characterize and assess the structure condition. This includes composite condition after manufacture (such as fiber orientation and density, porosity, delamination, and bond strength) and during usage (such as damage from impact, fiber breakage, thermal exposure or applied stress). Ultrasonic and thermographic methods can address some of these challenges, but eddy current methods provide an alternative method for composite structures that contain a conducting material, such as carbon fibers or a metallic liner. This presentation reviews recent advances in the development of eddy current sensors and arrays for carbon fiber composite NDT and Structural Health Monitoring (SHM) applications. The focus is on eddy current sensor constructs with linear drive windings, such as MWM -Arrays, that induce currents primarily within the linear fibers of the composite. By combining this type of sensor construct with micromechanical models that relate composite constituent properties to measurable sensor responses, insight is obtained into the volumetric distribution of electrical properties within the composite and the associated manufacturing, damage, or strain conditions. With knowledge of the fiber layup, this MWM-Array technology is able to detect damage and strain/stress as a function of depth and fiber orientation. This work has been funded by NASA, NA V AIR and the Army for applications ranging from composite overwrapped pressure vessels (COPVs) to aircraft structures and rotorcraft blades. This presentation will specifically present background on the MWM-Array technology, results from the micromechanical modeling effort, and results from

  11. Transverse Coefficient of Thermal Expansion Measurements of Carbon Fibers Using ESEM at High Temperatures

    NASA Technical Reports Server (NTRS)

    Ochoa, O.; Jiang, J.; Putnam, D.; Lo, Z.; Ellis, A.; Effinger, Michael

    2003-01-01

    The transverse coefficient of thermal expansion (CTE) of single IM7, T1000, and P55 carbon fibers are measured at elevated temperatures. The specimens are prepared by press-fitting fiber tows into 0.7mm-diameter cavity in a graphite disk of 5mm in diameter and 3mm high. The specimens are placed on a crucible in an ESEM, and images of the fiber cross section are taken as the fibers are heated up to 800 C. Holding time, heating and cool down cycles are also introduced. The geometrical changes are measured using a graphics tablet. The change in area/perimeter is calculated to determine the strain and transverse CTE for each fiber. In a complimentary computational effort, displacements and stresses are calculated with finite element models.

  12. Synergistic effect of self-assembled carboxylic acid-functionalized carbon nanotubes and carbon fiber for improved electro-activated polymeric shape-memory nanocomposite

    NASA Astrophysics Data System (ADS)

    Lu, Haibao; Min Huang, Wei

    2013-06-01

    The present work studies the synergistic effect of self-assembled carboxylic acid-functionalized carbon nanotube (CNT) and carbon fiber on the electrical property and electro-activated recovery behavior of shape memory polymer (SMP) nanocomposites. The combination of CNT and carbon fiber results in improved electrical conductivity in the SMP nanocomposites. Carboxylic acid-functionalized CNTs are grafted onto the carbon fibers and then self-assembled by deposition to significantly enhance the reliability of the bonding between carbon fiber and SMP via van der Waals and covalent crosslink. Furthermore, the self-assembled carboxylic acid-functionalized CNTs and carbon fibers enable the SMP nanocomposites for Joule heating triggered shape recovery.

  13. Electroadsorption desalination with carbon nanotube/PAN-based carbon fiber felt composites as electrodes.

    PubMed

    Liu, Yang; Zhou, Junbo

    2014-01-01

    The chemical vapor deposition method is used to prepare CNT (carbon nanotube)/PCF (PAN-based carbon fiber felt) composite electrodes in this paper, with the surface morphology of CNT/PCF composites and electroadsorption desalination performance being studied. Results show such electrode materials with three-dimensional network nanostructures having a larger specific surface area and narrower micropore distribution, with a huge number of reactive groups covering the surface. Compared with PCF electrodes, CNT/PCF can allow for a higher adsorption and desorption rate but lower energy consumption; meanwhile, under the condition of the same voltage change, the CNT/PCF electrodes are provided with a better desalination effect. The study also found that the higher the original concentration of the solution, the greater the adsorption capacity and the lower the adsorption rate. At the same time, the higher the solution's pH, the better the desalting; the smaller the ions' radius, the greater the amount of adsorption. PMID:24963504

  14. Liquid-phase adsorption of organic compounds by granular activated carbon and activated carbon fibers

    SciTech Connect

    Lin, S.H.; Hsu, F.M.

    1995-06-01

    Liquid-phase adsorption of organic compounds by granular activated carbon (GAC) and activated carbon fibers (ACFs) is investigated. Acetone, isopropyl alcohol (IPA), phenol, and tetrahydrofuran (THF) were employed as the model compounds for the present study. It is observed from the experimental results that adsorption of organic compounds by GAC and ACF is influenced by the BET (Brunauer-Emmett-Teller) surface area of adsorbent and the molecular weight, polarity, and solubility of the adsorbate. The adsorption characteristics of GAC and ACFs were found to differ rather significantly. In terms of the adsorption capacity of organic compounds, the time to reach equilibrium adsorption, and the time for complete desorption, ACFs have been observed to be considerably better than GAC. For the organic compounds tested here, the GAC adsorptions were shown to be represented well by the Langmuir isotherm while the ACF adsorption could be adequately described by the Langmuir or the Freundlich isotherm. Column adsorption tests indicated that the exhausted ACFs can be effectively regenerated by static in situ thermal desorption at 150 C, but the same regeneration conditions do not do as well for the exhausted GAC.

  15. Electroadsorption Desalination with Carbon Nanotube/PAN-Based Carbon Fiber Felt Composites as Electrodes

    PubMed Central

    Liu, Yang; Zhou, Junbo

    2014-01-01

    The chemical vapor deposition method is used to prepare CNT (carbon nanotube)/PCF (PAN-based carbon fiber felt) composite electrodes in this paper, with the surface morphology of CNT/PCF composites and electroadsorption desalination performance being studied. Results show such electrode materials with three-dimensional network nanostructures having a larger specific surface area and narrower micropore distribution, with a huge number of reactive groups covering the surface. Compared with PCF electrodes, CNT/PCF can allow for a higher adsorption and desorption rate but lower energy consumption; meanwhile, under the condition of the same voltage change, the CNT/PCF electrodes are provided with a better desalination effect. The study also found that the higher the original concentration of the solution, the greater the adsorption capacity and the lower the adsorption rate. At the same time, the higher the solution's pH, the better the desalting; the smaller the ions' radius, the greater the amount of adsorption. PMID:24963504

  16. Direct synthesis of nanoporous carbon nitride fibers using Al-based porous coordination polymers (Al-PCPs).

    PubMed

    Hu, Ming; Reboul, Julien; Furukawa, Shuhei; Radhakrishnan, Logudurai; Zhang, Yuanjian; Srinivasu, Pavuluri; Iwai, Hideo; Wang, Hongjing; Nemoto, Yoshihiro; Suzuki, Norihiro; Kitagawa, Susumu; Yamauchi, Yusuke

    2011-07-28

    We report a new synthetic route for preparation of nanoporous carbon nitride fibers with graphitic carbon nitride polymers, by calcination of Al-based porous coordination polymers (Al-PCPs) with dicyandiamide (DCDA) under a nitrogen atmosphere.

  17. Investigation of Carbon-Polymer Structures with Embedded Fiber-Optic Bragg Gratings

    NASA Technical Reports Server (NTRS)

    Grant, Joseph; Kaul, R.; Taylor, S.; Myers, G.; Sharma, A.

    2003-01-01

    Several Bragg-grating sensors fabricated within the same optical fiber are buried within multiple-ply carbon-epoxy planar and cylindrical structures. Effect of different orientation of fiber-sensors with respect to carbon fibers in the composite structure is investigated. This is done for both fabric and uni-tape material samples. Response of planar structures to axial and transverse strain up to 1 millistrain is investigated with distributed Bragg-grating sensors. Material properties like Young's Modulus and Poisson ratio is measured. A comparison is made between response measured by sensors in different ply-layers and those bonded on the surface. The results from buried fiber- sensors do not completely agree with surface bonded conventional strain gauges. A plausible explanation is given for observed differences. The planar structures are subjected to impacts with energies up to 10 ft-lb. Effect of this impact on the material stiffness is also investigated with buried fiber-optic Bragg sensors. The strain response of such optical sensors is also measured for cylindrical carbon-epoxy composite structures. The sensors are buried within the walls of the cylinder as well as surface bonded in both the axial as well as hoop directions. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 1500 psi. This is done at both room temperature as well as cryogenic temperatures. The recorded response is compared with that from a conventional strain gauge.

  18. Carbon nanotube fibers and ribbons produced by a novel wet-spinning process

    NASA Astrophysics Data System (ADS)

    Capps, Ryan Cody

    Carbon nanotubes have exciting potential to provide high performance materials of the future. One of the main challenges is assembling the billions of miles of individual nanotubes in each pound of product nanotube fiber or sheet in such a way that the properties of the individual nanotubes are most effectively utilized. In this study a novel wet fiber spinning method was developed in which carbon nanotubes dispersed in a surfactant are injected into a rotating acid bath which coagulates the dispersion to form a macroscopic fiber. This flocculation method produces highly conducting carbon nanotube fibers and sheets without the need for a polymer binder. The mechanical strength is sufficient for several applications and can be improved by either heat treatment or by incorporation of a polymer in the yarn, and subsequent draw. Poly(Vinyl Alcohol) (PVA)-treated fibers yield outstanding mechanical properties and a toughness that is comparable to spider silk. Other polymers, such as polyvinylpyrrolidone (PVP) also enhance mechanical properties. Inorganic additives, such as platinum, can be incorporated into the fiber matrix to provide multifunctionality.

  19. The deposition of boron nitride and carbon films on silica glass fibers

    SciTech Connect

    Smith, W.L.; Michalske, T.A.; Rye, R.R.

    1993-11-01

    A chemical vapor deposition technique is used to produce amorphous boron nitride and carbon thin films on high strength silica glass fibers. In this method, the fiber is drawn under ultra high vacuum conditions and low pressure process gases, in the presence of a hot tungsten filament, are used to grow films at low substrate temperatures. Films deposited with this technique do not degrade the intrinsic pristine strength of the silica fibers under dry conditions and, when stressed in chemically aggressive environments, act as effective barrier coatings.

  20. Crystalline and tensile properties of carbon nanotube and graphene reinforced polyamide 12 fibers

    NASA Astrophysics Data System (ADS)

    Chatterjee, S.; Nüesch, F. A.; Chu, B. T. T.

    2013-02-01

    The influence of carbon nanotubes (CNTs) and graphene nanoplatelets (GnPs) on the structure and mechanical properties of polyamide 12 (PA12) fibers was investigated. As seen from wide-angle X-ray diffraction analysis the crystallinity index increases with incorporation of nanofillers due to nucleation effects. Marked improvement was noted for mechanical properties of the composites with increase in elastic modulus, yield stress and strength of the fibers. The most significant improvement of a factor of 4 could be observed for elastic modulus with the inclusion of 0.5 wt.% GnP. A comparative study was made between the fibers reinforced with CNTs and GnPs.

  1. A Mechanically Actuating Carbon-Nanotube Fiber in Response to Water and Moisture.

    PubMed

    He, Sisi; Chen, Peining; Qiu, Longbin; Wang, Bingjie; Sun, Xuemei; Xu, Yifan; Peng, Huisheng

    2015-12-01

    A new family of hierarchically helical carbon-nanotube fibers with many nano- and micro-scale channels has been synthesized. They demonstrate remarkable mechanical actuations in response to water and moisture. The water or moisture is first rapidly transported through the trunk micron-scale channels and then efficiently infiltrates into the interconnected capillary nanoscale channels, similar to the blood flow in our body. Therefore, rapid and large contraction and rotation of the fiber occurs with a high reversibility. These mechanically actuating fibers are promising for various applications, and smart windows and louvers have been investigated as two demonstrations. PMID:26460095

  2. Polymer-derived ceramic composite fibers with aligned pristine multiwalled carbon nanotubes.

    PubMed

    Sarkar, Sourangsu; Zou, Jianhua; Liu, Jianhua; Xu, Chengying; An, Linan; Zhai, Lei

    2010-04-01

    Polymer-derived ceramic fibers with aligned multiwalled carbon nanotubes (MWCNTs) are fabricated through the electrospinning of polyaluminasilazane solutions with well-dispersed MWCNTs followed by pyrolysis. Poly(3-hexylthiophene)-b-poly (poly (ethylene glycol) methyl ether acrylate) (P3HT-b-PPEGA), a conjugated block copolymer compatible with polyaluminasilazane, is used to functionalize MWCNT surfaces with PPEGA, providing a noninvasive approach to disperse carbon nanotubes in polyaluminasilazane chloroform solutions. The electrospinning of the MWCNT/polyaluminasilazane solutions generates polymer fibers with aligned MWCNTs where MWCNTs are oriented along the electrospun jet by a sink flow. The subsequent pyrolysis of the obtained composite fibers produces ceramic fibers with aligned MWCNTs. The study of the effect of polymer and CNT concentration on the fiber structures shows that the fiber size increases with the increment of polymer concentration, whereas higher CNT content in the polymer solutions leads to thinner fibers attributable to the increased conductivity. Both the SEM and TEM characterization of the polymer and ceramic fibers demonstrates the uniform orientation of CNTs along the fibers, suggesting excellent dispersion of CNTs and efficient CNT alignment via the electrospinning. The electrical conductivity of a ceramic fibers with 1.2% aligned MWCNTs is measured to be 1.58 x 10(-6) S/cm, which is more than 500 times higher than that of bulk ceramic (3.43 x 10(-9) S/cm). Such an approach provides a versatile method to disperse CNTs in preceramic polymer solutions and offers a new approach to integrate aligned CNTs in ceramics. PMID:20423134

  3. A comparative study of the stress-rupture lifetimes of high-strength carbon fibers

    NASA Astrophysics Data System (ADS)

    Grimes-Ledesma, Lorie

    Stress-rupture life is the time a composite can survive under load at an assigned risk level. The stress-rupture lifetimes of high-strength PAN-based carbon fibers are important to the development and use of lightweight composite structures such as composite overwrapped pressure vessels (COPVs). To quantify appropriate stress-rupture risk levels based on available models, quantification of single fiber variability and lifetime is necessary to understand the variability observed in larger composite structures. In the present work, three PAN-based carbon fibers commonly used in COPV technology were examined, Hexcel IM9, Toray T700, and Toray T1000. The diameter of each fiber type was quantified by measuring samples in the scanning electron microscope and failure loads were determined by performing tensile tests on single fibers. Weibull statistics were used to describe the results. Fractography was performed on IM9 and T1000 fibers after tensile failure. The fracture surfaces are consistent with crack growth from a volume or surface defect. Stress-rupture testing was completed at two stress levels at each fiber type, 97% and 93% of the mean fiber strength for each of the fiber types. The results indicate that differences in stress-rupture life performance exist between the three fiber types. Differences in stress ratio of between 5 and 10% were observed, which may translate to significant difference in stress-rupture life behavior for larger composite structures. The results indicate that a relationship may exist between strength and stress-rupture life. However, if this relationship exists, it is not a simple one, and the relationship is likely complicated by manufacturing.

  4. Carbon-fiber microelectrodes modified with 4-sulfobenzene have increased sensitivity and selectivity for catecholamines

    PubMed Central

    Hermans, Andre; Seipel, Andrew T.; Miller, Charles E.; Wightman, R. Mark

    2008-01-01

    Elliptical and cylindrical geometries of carbon-fiber microelectrodes were modified by covalent attachment of 4-sulfobenzenediazonium tetrafluoroborate following its electroreduction. Elliptical electrodes fabricated from Thornel P-55 carbon fibers show the highest amount of 4-sulfobenzene attached to the electrode. Fast-scan cyclic voltammetry was used to compare the response to dopamine and other neurochemicals at these modified carbon-fiber microelectrodes. The grafted layer causes an increased sensitivity to dopamine and other positively charged analytes that is due to increased adsorption of analyte in the grafted layer. However, this layer remains permeable to negatively charged compounds. Modified electrodes retain the increased sensitivity for dopamine during measurements in mouse brain tissue. PMID:16489775

  5. Gasification of carbon fiber composites for the alleviation of electrical hazards

    NASA Technical Reports Server (NTRS)

    Hull, G.; Glazer, C. R.; Harper-Tervet, J.; Humphrey, M. F.; Ramohalli, K. N.

    1981-01-01

    A mixture of calcium acetate and lithium acetate applied to the surface of carbon fibers caused the fibers to gasify in a simulated airplane-crash fire. Tests conducted with a JPL-developed electrical detector showed the catalyst-modified composites to release few fibers during burning, while state-of-the-art composites released several hundred. Mechanical property tests demonstrated nearly identical behavior of catalyst-modified and state-of-the-art composites. Aging tests also showed little difference in the composite strength except for a severe reduction when soaked in water. Several promising new concepts resulted from the project, including catalytic elimination of carbon particulates from diesel exhaust, catalytic improvement of coal combustion, and electrical destruction of carbon particulates in combustion systems.

  6. A Precious Metal-Free Electroless Technique for the Deposition of Copper on Carbon Fibers

    NASA Astrophysics Data System (ADS)

    Che, Dehui; Yao, Guangchun; Cao, Zhuokun

    2012-11-01

    This article introduces a new technique of electroless copper deposition on carbon fibers in the absence of precious metal as the catalyst. Copper layers were electrolessly deposited on the surface of carbon fiber without using the conventional palladium or silver catalyst to initiate redox reactions leading to metallization. This new technique shows that nickel seeds can serve as excellent catalysts to expedite the redox reactions. By performing experiments, parameters such as activation temperature, nickel ion concentration, and pH value were optimized, and an orbicular copper plating layer of carbon fiber was obtained in the copper sulfate salt-based conventional electroless solution. The surface morphology of copper coating was characterized by scanning electron microscopy and X-ray diffraction. The results indicate that uniform and smooth copper coating could be obtained by the new precious-metal free activation process. The resulting copper coating thickness is about 1 μm.

  7. Relation between the charge efficiency of activated carbon fiber and its desalination performance.

    PubMed

    Huang, Zheng-Hong; Wang, Ming; Wang, Lei; Kang, Feiyu

    2012-03-20

    Four types of activated carbon fibers (ACFs) with different specific surface areas (SSA) were used as electrode materials for water desalination using capacitive deionization (CDI). The carbon fibers were characterized by scanning electron microscopy and N(2) adsorption at 77 K, and the CDI process was investigated by studying the salt adsorption, charge transfer, and also the charge efficiency of the electric double layers that are formed within the micropores inside the carbon electrodes. It is found that the physical adsorption capacity of NaCl by the ACFs increases with increasing Brunauer-Emmett-Teller (BET) surface area of the fibers. However, the two ACF materials with the highest BET surface area have the lowest electrosorptive capability. Experiments indicate that the charge efficiency of the double layers is a key property of the ACF-based electrodes because the ACF material which has the maximum charge efficiency also shows the highest salt adsorption capacity for CDI.

  8. Alignment of carbon nanotubes and reinforcing effects in nylon-6 polymer composite fibers

    NASA Astrophysics Data System (ADS)

    Rangari, Vijaya K.; Yousuf, Mohammed; Jeelani, Shaik; Pulikkathara, Merlyn X.; Khabashesku, Valery N.

    2008-06-01

    Alignment of pristine carbon nanotubes (P-CNTs) and fluorinated carbon nanotubes (F-CNTs) in nylon-6 polymer composite fibers (PCFs) has been achieved using a single-screw extrusion method. CNTs have been used as filler reinforcements to enhance the mechanical and thermal properties of nylon-6 composite fibers. The composites were fabricated by dry mixing nylon-6 polymer powder with the CNTs as the first step, then followed by the melt extrusion process of fiber materials in a single-screw extruder. The extruded fibers were stretched to their maxima and stabilized using a godet set-up. Finally, fibers were wound on a Wayne filament winder machine and tested for their tensile and thermal properties. The tests have shown a remarkable change in mechanical and thermal properties of nylon-6 polymer fibers with the addition of 0.5 wt% F-CNTs and 1.0 wt% of P-CNTs. To draw a comparison between the improvements achieved, the same process has been repeated with neat nylon-6 polymer. As a result, tensile strength has been increased by 230% for PCFs made with 0.5% F-CNTs and 1% P-CNTs as additives. These fibers have been further characterized by DSC, Raman spectroscopy and SEM which confirm the alignment of CNTs and interfacial bonding to nylon-6 polymer matrix.

  9. Crystallization and assembling behavior of calcium carbonate controlled by Ca-organic fibers

    NASA Astrophysics Data System (ADS)

    Chen, Anliang; Ma, Peiyan; Fu, Zhengyi; Wu, Yan; Kong, Wei

    2013-08-01

    Calcium carbonate (CaCO3) crystals with different phases were obtained on the basis of one-dimensional Ca-deoxycholate fibers (Ca-DC fibers) under ambient conditions. Ca-DC fibers were prepared by the combination of Ca2+ ions and sodium deoxycholate (SDC) before the addition of sodium bicarbonate. Vaterite dominated mixtures could be easily obtained in the presence of Ca-DC fibers in the aqueous system at 10 °C. As the temperature was increased to 30 and 120 °C, pure vaterite and aragonite with novel morphologies were obtained, respectively. The framework formed by one-dimensional Ca-DC fibers was demonstrated to be the key role in mediating the crystallization and assembling behaviors of calcium carbonate. In this study, Ca-DC fibers, prepared as a novel insoluble organic polymorph controller, could even play an important role in the industrial production of CaCO3 with different polymorphs in future and other similar Ca-organic fibers are believed to have same functions as well.

  10. Flue gas carbon dioxide sequestration during water softening with ion-exchange fibers

    SciTech Connect

    Greenleaf, J.E.; SenGupta, A.K.

    2009-06-15

    This study examines the use of ion-exchange fibers (IX fibers) to permanently sequester carbon dioxide present in flue gas into an aqueous phase as calcium or magnesium alkalinity while concurrently softening hard water. The only process inputs besides carbon dioxide (or flue gas) are snowmelt (or rainwater); no other chemicals are required for the regeneration of the IX fibers. Importantly, the process is not energy intensive and carbon dioxide does not need to be compressed to excessive pressures (>150 psi) for efficient use. Sources of carbon dioxide do not require concentration and, therefore, the use of raw flue gas (similar to 17% CO{sub 2}) is feasible with the rate of sequestration governed only by the partial pressure of carbon dioxide. While valid for flue gas obtained from any combustion process (e.g., coal, oil, natural gas, etc.), emissions from oil or gas combustion may be more appropriate for use in the described process due to the absence of mercury and particulates. It should also be noted that the presence of sulfur dioxide in flue gas would not adversely affect the process and may even enhance regeneration efficiency. The only product of the proposed process is an environmentally benign regenerant stream containing calcium and/or magnesium alkalinity. The unique property of IX fibers that makes the proposed process both environmentally sustainable and economically feasible is amenability to efficient regeneration with carbon dioxide and harvested snowmelt. Low intraparticle diffusional resistance is the underlying reason why IX fibers are amenable to efficient regeneration using snowmelt sparged with carbon dioxide; 95% calcium recovery was attained at a CO{sub 2} partial pressure of 6.8 atm. The energy balance for a typical electric utility shows that up to 1% of carbon dioxide emitted during combustion would be sequestered in the softening process.

  11. Characterization of adhesion at carbon fiber-fluorinated epoxy interface and effect of environmental degradation

    NASA Astrophysics Data System (ADS)

    Dasgupta, Suman

    2011-12-01

    Carbon fiber reinforced polymers are excellent candidates for aerospace, automobile and other mobile applications due to their high specific strength and modulus. The most prominent aerospace application of carbon fiber composites in recent times is the Boeing 787 Dreamliner, which is the world's first major commercial airliner to extensively use composite materials. The critical issue, which needs to be addressed hereby, is long-term safety. Hence, long-term durability of composite materials in such applications becomes a point of concern. Conventional polymer matrices, such as thermosetting resins, which are used as matrix material in carbon fiber composites, are susceptible to degradation in the form of chemical corrosion, UV degradation and moisture, in severe environmental conditions. Fluorinated polymers offer a viable alternative as matrix material, due to their reduced susceptibility to environmental degradation. The epoxy system used in this study is fluorinated Tetra-glycidyl methylene di-aniline (6F-TGMDA), which was developed by polymer scientists at NASA Langley Research Center. The hydrophobic nature of this epoxy makes it a potential matrix material in aerospace applications. However, its compatibility in carbon fiber-reinforced composites remains to be investigated. This study aims to characterize the interfacial properties in carbon fiber reinforced fluorinated epoxy composites. Typical interfacial characterization parameters, like interfacial shear strength, estimated from the microbond test, proved to be inadequate in accurately estimating adhesion since it assumes a uniform distribution of stresses along the embedded fiber length. Also, it does not account for any residual stresses present at the interface, which might arise due to thermal expansion differences and Poisson's ratio differences of the fiber and matrix. Hence, an analytical approach, which calculates adhesion pressure at the interface, was adopted. This required determination of

  12. Surface characterization of carbon fiber polymer composites and aluminum alloys after laser interference structuring

    DOE PAGES

    Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian; Warren, Charles David; Daniel, Claus

    2016-05-03

    Here, the increasing use of Carbon Fiber-reinforced Polymer matrix Composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (a) structuring of the AL 5182 surface, (b) removal of the resin layer on top of carbon fibers, and (c) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg - T83 epoxy, 5 ply thick, 0/90o plaques weremore » used. The effect of laser fluence, scanning speed, and number of shots-per-spot was investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope (SEM) imaging were used to study the effect of the laser processing on surface morphology.« less

  13. Commercialization of New Carbon Fiber Materials Based on Sustainable Resources for Energy Applications

    SciTech Connect

    Eberle, Cliff; Webb, Daniel C; Albers, Tracy; Chen, Chong

    2013-03-01

    Oak Ridge National Laboratory (ORNL) and GrafTech International have collaborated to develop and demonstrate the performance of high temperature thermal insulation prototypes made from lignin-based carbon fibers. This project will potentially lead to the first commercial application of lignin-based carbon fibers (LBCF). The goal of the commercial application is to replace expensive, Chinese-sourced isotropic pitch carbon fibers with lower cost carbon fibers made from a domestically sourced, bio-derived (renewable) feedstock. LBCF can help recapture jobs that were previously exported to China while resolving a supply chain vulnerability and reducing the production cost for GrafTech s high temperature thermal insulation. The performance of the LBCF prototypes was measured and found to be comparable to that of the current commercial product. During production of the insulation prototypes, ORNL and GrafTech demonstrated lignin compounding/pelletization, fiber production, heat treatment, and compositing at scales far surpassing those previously demonstrated in LBCF R&D or production. A plan was developed for the commercialization of LBCF thermal insulation, with key milestones including qualification of multiple scalable lignin sources in 2013, tons-scale production and field testing by customers in 2014, and product launch as soon thereafter as production capabilities can be constructed and commissioned.

  14. Propagation of PAMAM dendrimers on the carbon fiber surface by in situ polymerization: a novel methodology for fiber/matrix composites

    NASA Astrophysics Data System (ADS)

    Zhang, R. L.; Gao, B.; Zhang, J.; Cui, H. Z.; Li, D. W.

    2015-12-01

    A facile strategy for generating dendrimers onto carbon fibers, in order to functionalize them, was reported. Dendrimers were propagated on the surface of carbon fibers by in situ polymerization with Michael addition. The changes in morphology, surface composition and surface energy, which were studied by atomic force microscope (AFM), dynamic contact angle analysis test (DCAT) and x-ray photoelectron microscopy (XPS), were related to the interfacial performance of model composites. In addition, the level of fiber-matrix adhesion was determined by the interlaminar shear strength (ILSS) test. Experimental results indicated that some dendritic polymer was successfully grown on the fiber surface through the chemical reaction, and this significantly enhanced the interfacial bonding of the carbon fiber composites.

  15. Apparatus and process for the surface treatment of carbon fibers

    DOEpatents

    Paulauskas, Felix Leonard; Ozcan, Soydan; Naskar, Amit K.

    2016-05-17

    A method for surface treating a carbon-containing material in which carbon-containing material is reacted with decomposing ozone in a reactor (e.g., a hollow tube reactor), wherein a concentration of ozone is maintained throughout the reactor by appropriate selection of at least processing temperature, gas stream flow rate, reactor dimensions, ozone concentration entering the reactor, and position of one or more ozone inlets (ports) in the reactor, wherein the method produces a surface-oxidized carbon or carbon-containing material, preferably having a surface atomic oxygen content of at least 15%. The resulting surface-oxidized carbon material and solid composites made therefrom are also described.

  16. The vulnerability of commercial aircraft avionics to carbon fibers

    NASA Technical Reports Server (NTRS)

    Meyers, J. A.; Salmirs, S.

    1980-01-01

    Avionics components commonly used in commercial aircraft were tested for vulnerability to failure when operated in an environment with a high density of graphite fibers. The components were subjected to a series of exposures to graphite fibers of different lengths. Lengths used for the tests were (in order) 1 mm, 3 mm, and 10 mm. The test procedure included subjecting the equipment to characteristic noise and shock environments. Most of the equipment was invulnerable or did not fail until extremely high average exposures were reached. The single exception was an air traffic control transponder produced in the early 1960's. It had the largest case open area through which fibers could enter and it had no coated boards.

  17. Fibers comprised of epitaxially grown single-wall carbon nanotubes, and a method for added catalyst and continuous growth at the tip

    DOEpatents

    Kittrell, W. Carter; Wang, Yuhuang; Kim, Myung Jong; Hauge, Robert H.; Smalley, Richard E.; Marek leg, Irene Morin

    2010-06-01

    The present invention is directed to fibers of epitaxially grown single-wall carbon nanotubes (SWNTs) and methods of making same. Such methods generally comprise the steps of: (a) providing a spun SWNT fiber; (b) cutting the fiber substantially perpendicular to the fiber axis to yield a cut fiber; (c) etching the cut fiber at its end with a plasma to yield an etched cut fiber; (d) depositing metal catalyst on the etched cut fiber end to form a continuous SWNT fiber precursor; and (e) introducing feedstock gases under SWNT growth conditions to grow the continuous SWNT fiber precursor into a continuous SWNT fiber.

  18. MATERIALS DEVELOPMENT FOR PULP AND PAPER MILLS, TASK 9 PROOF OF COMMERCIAL CONCEPT: COMMODITY CARBON FIBERS FROM WEYERHAEUSER LIGNIN BASED FIBERS

    SciTech Connect

    Paulauskas, F.L.; Naskar, A.K.; S. Ozcan; J. R. Keiser; Gorog, J.P.

    2010-08-15

    Tasks were assigned to Oak Ridge National Laboratory (ORNL) researchers for the development of lignin-based carbon fiber from a specific precursor that was produced by the Participant (Weyerhaeuser Corporation). These tasks included characterization of precursor polymers and fibers; and the development of conversion parameters for the fibers. ORNL researchers provided recommendations for in-house characterization of the precursor at the participant’s laboratory.

  19. Curing agent for polyepoxides and epoxy resins and composites cured therewith. [preventing carbon fiber release

    NASA Technical Reports Server (NTRS)

    Serafini, T. T.; Delvigs, P.; Vannucci, R. D. (Inventor)

    1981-01-01

    A curing for a polyepoxide is described which contains a divalent aryl radical such as phenylene a tetravalent aryl radical such as a tetravalent benzene radical. An epoxide is cured by admixture with the curing agent. The cured epoxy product retains the usual properties of cured epoxides and, in addition, has a higher char residue after burning, on the order of 45% by weight. The higher char residue is of value in preventing release to the atmosphere of carbon fibers from carbon fiber-epoxy resin composites in the event of burning of the composite.

  20. Studies on non-oxide coating on carbon fibers using plasma enhanced chemical vapor deposition technique

    NASA Astrophysics Data System (ADS)

    Patel, R. H.; Sharma, S.; Prajapati, K. K.; Vyas, M. M.; Batra, N. M.

    2016-05-01

    A new way of improving the oxidative behavior of carbon fibers coated with SiC through Plasma Enhanced Chemical Vapor Deposition technique. The complete study includes coating of SiC on glass slab and Stainless steel specimen as a starting test subjects but the major focus was to increase the oxidation temperature of carbon fibers by PECVD technique. This method uses relatively lower substrate temperature and guarantees better stoichiometry than other coating methods and hence the substrate shows higher resistance towards mechanical and thermal stresses along with increase in oxidation temperature.

  1. Controlling the set of carbon-fiber embedded cement with electric current

    DOEpatents

    Mattus, Alfred J.

    2004-06-15

    A method for promoting cement or concrete set on demand for concrete that has been chemically retarded by adding carbon fiber to the concrete, which enables it to become electrically conductive, sodium tartrate retardant, and copper sulfate which forms a copper tartrate complex in alkaline concrete mixes. Using electricity, the concrete mix anodically converts the retarding tartrate to an insoluble polyester polymer. The carbon fibers act as a continuous anode surface with a counter electrode wire embedded in the mix. Upon energizing, the retarding effect of tartrate is defeated by formation of the polyester polymer through condensation esterification thereby allowing the normal set to proceed unimpeded.

  2. Integrated carbon fiber electrodes within hollow polymer microneedles for transdermal electrochemical sensing

    PubMed Central

    Miller, Philip R.; Gittard, Shaun D.; Edwards, Thayne L.; Lopez, DeAnna M.; Xiao, Xiaoyin; Wheeler, David R.; Monteiro-Riviere, Nancy A.; Brozik, Susan M.; Polsky, Ronen; Narayan, Roger J.

    2011-01-01

    In this study, carbon fiber electrodes were incorporated within a hollow microneedle array, which was fabricated using a digital micromirror device-based stereolithography instrument. Cell proliferation on the acrylate-based polymer used in microneedle fabrication was examined with human dermal fibroblasts and neonatal human epidermal keratinocytes. Studies involving full-thickness cadaveric porcine skin and trypan blue dye demonstrated that the hollow microneedles remained intact after puncturing the outermost layer of cadaveric porcine skin. The carbon fibers underwent chemical modification in order to enable detection of hydrogen peroxide and ascorbic acid; electrochemical measurements were demonstrated using integrated electrode-hollow microneedle devices. PMID:21522504

  3. Metallic conductivity and air stability in copper chloride intercalated carbon fibers

    NASA Technical Reports Server (NTRS)

    Oshima, H.; Woollam, J. A.; Yavrouian, A.

    1982-01-01

    Carbon-copper chloride intercalation compounds have been obtained by using variously graphitized carbon fibers as host materials. The resultant conductors are air stable, thermally stable to 450 K, have electrical resistivities as low as 12.9 microohm cm at room temperature, and have metallic conductivity temperature dependencies. These intercalated fibers have tensile strengths of 160000 psi, and Young's moduli of 25 x 10 to the 6th psi. For aerospace use, 1/(resistivity x density) is a figure of merit. On this basis, a reduction in resistivity by a factor of two will make this conductor competitive with copper.

  4. CRADA Final Report: Materials Development For Pulp and Paper Mills, Task 9 Proof of Commercial Concept: Commodity Carbon Fibers From Weyerhaeuser Lignin Based Fibers

    SciTech Connect

    Paulauskas, Felix L; Naskar, Amit K; Ozcan, Soydan; Keiser, James R; Gorog, John Peter

    2010-09-01

    Tasks were assigned to Oak Ridge National Laboratory (ORNL) researchers for the development of lignin-based carbon fiber from a specific precursor that was produced by the Participant (Weyerhaeuser Corporation). These tasks included characterization of precursor polymers and fibers; and the development of conversion parameters for the fibers. ORNL researchers provided recommendations for in-house characterization of the precursor at the participant's laboratory. During the early stage of the precursor fiber production trials of various spools of fibers with varied compositions were produced. Some of those samples were sent to ORNL (by the Participant) for the development of conversion protocol. The trial tow samples were oxidized at ORNL's precursor evaluation system (PES), a bench-scale facility consisting of an oven, filament winder, tension controller, and a let off creel. The PES is a modular tool useful for the development of precursor conversion protocol. It can handle a single filament to a large single tow (50k filaments). It can also offer precise tensioning for few-filament tows. In the PES, after oxidation, fibers are typically carbonized first at low temperature, {le} 600 C, and subsequently at a higher temperature, {le} 1200 C with controlled residence time. ORNL has recently installed a new carbonization furnace with 1700 C limit and a furnace with 2500 C capacity is under installation. A protocol for the oxidation and carbonization of the trial precursor fibers was developed. Oxidized fiber with a density of 1.46 g/cc (oxidation time: 90 min) shows qualitative flame retardancy via simple flame test (fibers do not catch fire or shrink when exposed to flame). Oxidized and carbonized filaments of the Weyerhaeuser precursor fibers show moderate mechanical properties and 47-51 % carbon yield (based on oxidized fiber mass) after carbonization between 1000-1400 C. The properties of fibers from nonoptimized composition and processing parameters indicate the

  5. Corrosion detection of steel reinforced concrete using combined carbon fiber and fiber Bragg grating active thermal probe

    NASA Astrophysics Data System (ADS)

    Li, Weijie; Ho, Siu Chun Michael; Song, Gangbing

    2016-04-01

    Steel reinforcement corrosion is one of the dominant causes for structural deterioration for reinforced concrete structures. This paper presents a novel corrosion detection technique using an active thermal probe. The technique takes advantage of the fact that corrosion products have poor thermal conductivity, which will impede heat propagation generated from the active thermal probe. At the same time, the active thermal probe records the temperature response. The presence of corrosion products can thus be detected by analyzing the temperature response after the injection of heat at the reinforcement-concrete interface. The feasibility of the proposed technique was firstly analyzed through analytical modeling and finite element simulation. The active thermal probe consisted of carbon fiber strands to generate heat and a fiber optic Bragg grating (FBG) temperature sensor. Carbon fiber strands are used due to their corrosion resistance. Wet-dry cycle accelerated corrosion experiments were performed to study the effect of corrosion products on the temperature response of the reinforced concrete sample. Results suggest a high correlation between corrosion severity and magnitude of the temperature response. The technique has the merits of high accuracy, high efficiency in measurement and excellent embeddability.

  6. Morphology dependent field emission of acid-spun carbon nanotube fibers

    NASA Astrophysics Data System (ADS)

    Fairchild, S. B.; Boeckl, J.; Back, T. C.; Ferguson, J. B.; Koerner, H.; Murray, P. T.; Maruyama, B.; Lange, M. A.; Cahay, M. M.; Behabtu, N.; Young, C. C.; Pasquali, M.; Lockwood, N. P.; Averett, K. L.; Gruen, G.; Tsentalovich, D. E.

    2015-03-01

    Acid spun carbon nanotube (CNT) fibers were investigated for their field emission properties and performance was determined to be dependent on fiber morphology. The fibers were fabricated by wet-spinning of pre-made CNTs. Fiber morphology was controlled by a fabrication method and processing conditions, as well as purity, size, and type of the CNT starting material. The internal fiber structure consisted of CNT fibrils held together by van der Waals forces. Alignment and packing density of the CNTs affects the fiber’s electrical and thermal conductivity. Fibers with similar diameters and differing morphology were compared, and those composed of the most densely packed and well aligned CNTs were the best field emitters as exhibited by a lower turn-on voltage and a larger field enhancement factor. Fibers with higher electrical and thermal conductivity demonstrated higher maximum current before failure and longer lifetimes. A stable emission current at 3 mA was obtained for 10 h at a field strength of <1 V μm-1. This stable high current operation makes these CNT fibers excellent candidates for use as low voltage electron sources for vacuum electronic devices.

  7. Continuous electrodeposition for lightweight, highly conducting and strong carbon nanotube-copper composite fibers.

    PubMed

    Xu, Geng; Zhao, Jingna; Li, Shan; Zhang, Xiaohua; Yong, Zhenzhong; Li, Qingwen

    2011-10-01

    Carbon nanotube (CNT) fiber is a promising candidate for lightweight cables. The introduction of metal particles on a CNT fiber can effectively improve its electrical conductivity. However, the decrease in strength is observed in CNT-metal composite fibers. Here we demonstrate a continuous process, which combines fiber spinning, CNT anodization and metal deposition, to fabricate lightweight and high-strength CNT-Cu fibers with metal-like conductivities. The composite fiber with anodized CNTs exhibits a conductivity of 4.08 × 10(4)-1.84 × 10(5) S cm(-1) and a mass density of 1.87-3.08 g cm(-3), as the Cu thickness is changed from 1 to 3 μm. It can be 600-811 MPa in strength, as strong as the un-anodized pure CNT fiber (656 MPa). We also find that during the tensile tests there are slips between the inner CNTs and the outer Cu layer, leading to the drops in electrical conductivity. Therefore, there is an effective fiber strength before which the Cu layer is robust. Due to the improved interfacial bonding between the Cu layer and the anodized CNT surfaces, such effective strength is still high, up to 490-570 MPa. PMID:21879118

  8. Modeling the Tensile Strength of Carbon Fiber - Reinforced Ceramic - Matrix Composites Under Multiple Fatigue Loading

    NASA Astrophysics Data System (ADS)

    Li, Longbiao

    2016-06-01

    An analytical method has been developed to investigate the effect of interface wear on the tensile strength of carbon fiber - reinforced ceramic - matrix composites (CMCs) under multiple fatigue loading. The Budiansky - Hutchinson - Evans shear - lag model was used to describe the micro stress field of the damaged composite considering fibers failure and the difference existed in the new and original interface debonded region. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. The interface shear stress degradation model and fibers strength degradation model have been adopted to analyze the interface wear effect on the tensile strength of the composite subjected to multiple fatigue loading. Under tensile loading, the fibers failure probabilities were determined by combining the interface wear model and fibers failure model based on the assumption that the fiber strength is subjected to two - parameter Weibull distribution and the loads carried by broken and intact fibers satisfy the Global Load Sharing criterion. The composite can no longer support the applied load when the total loads supported by broken and intact fibers approach its maximum value. The conditions of a single matrix crack and matrix multicrackings for tensile strength corresponding to multiple fatigue peak stress levels and different cycle number have been analyzed.

  9. Multi-gigahertz repetition rate passively modelocked fiber lasers using carbon nanotubes.

    PubMed

    Martinez, Amos; Yamashita, Shinji

    2011-03-28

    There is an increasing demand for all-fiber passively mode-locked lasers with pulse repetition rates in the order of gigahertz for their potential applications in fields such as telecommunications and metrology. However, conventional mode-locked fiber lasers typically operate at fundamental repetition rates of only a few megahertz. In this paper, we report all-fiber laser operation with fundamental repetition rates of 4.24 GHz, 9.63 GHz and 19.45 GHz. This is, to date and to the best of our knowledge, the highest fundamental repetition rate reported for an all-fiber laser. The laser operation is based on the passive modelocking of a miniature all-fiber Fabry-Pérot laser (FFPL) by a carbon nanotube (CNT) saturable absorber. The key components for such device are a very high-gain Er:Yb phosphosilicate fiber and a fiber compatible saturable absorber with very small foot print and very low losses. The laser output of the three lasers was close to transform-limited with a pulsewidth of approximately 1 ps and low noise. As a demonstration of potential future applications for this laser, we also demonstrated supercontinuum generation with a longitudinal mode-spacing of 0.08 nm by launching the laser operating at 9.63 GHz into 30 m of a highly nonlinear dispersion shifted fiber.

  10. Distributed Sensing of Carbon-Epoxy Composites and Filament Wound Pressure Vessels Using Fiber-Bragg Gratings

    NASA Technical Reports Server (NTRS)

    Grant, J.; Kaul, R.; Taylor, S.; Myer, G.; Jackson, K.; Osei, A.; Sharma, A.

    2003-01-01

    Multiple Fiber Bragg-gratings are embedded in carbon-epoxy laminates as well as in composite wound pressure vessel. Structural properties of such composites are investigated. The measurements include stress-strain relation in laminates and Poisson's ratio in several specimens with varying orientation of the optical fiber Bragg-sensor with respect to the carbon fiber in an epoxy matrix. Additionally, fiber Bragg gratings are bonded on the surface of these laminates and cylinders fabricated out of carbon-epoxy composites and multiple points are monitored and compared for strain measurements at several locations.

  11. Nanostructural evolution during emission of CsI-coated carbon fiber cathodes

    NASA Astrophysics Data System (ADS)

    Drummy, Lawrence F.; Apt, Scott; Shiffler, Don; Golby, Ken; LaCour, Matt; Maruyama, Benji; Vaia, Richard A.

    2010-06-01

    Carbon-based nanofiber and microfiber cathodes exhibit very low voltages for the onset of electron emission, and thus provide exciting opportunities for applications ranging from high power microwave sources to field emission displays. CsI coatings have been experimentally shown to lower the work function for emission from the fiber tips, although little is known about the microstructure of the fibers themselves in their as-received state, after coating with CsI, or after being subjected to high voltage cycling. Longitudinal cross sections of the original, unused CsI-coated fibers produced by focused ion beam lift-out revealed a nanostructured graphitic core surrounded by an amorphous carbon shell with submicron sized islands of crystalline CsI on the outer surface. Aberration-corrected high resolution electron microscopy (HREM) of the fiber core achieved 0.10 nm resolution, with the graphite (200) clearly visible in digital fast Fourier transformations of the 2-4 nm highly ordered graphitic domains. As the cathode fibers are cycled at high voltage, HREM demonstrates that the graphitic ordering of the core increases with the number of cycles, however the structure and thickness of the amorphous carbon layer remains unchanged. These results are consistent with micro-Raman measurements of the fiber disordered/graphitic (D/G) band ratios. After high voltage cycling, a uniform ˜100 nm film at the fiber tip was evident in both bright field transmission electron microscopy (TEM) and high angle annular dark field scanning TEM (STEM). Low-dose electron diffraction techniques confirmed the amorphous nature of this film, and STEM with elemental mapping via x-ray energy dispersive spectroscopy indicates this layer is composed of CsIO. The oxidative evolution of tip composition and morphology due to impurities in the chamber, along with increased graphitization of the fiber core, contributes to changes in emission behavior with cycling.

  12. Shockwave response of two carbon fiber-polymer composites to 50 GPa

    NASA Astrophysics Data System (ADS)

    Dattelbaum, Dana M.; Coe, Joshua D.; Rigg, Paulo A.; Scharff, R. Jason; Gammel, J. Tinka

    2014-11-01

    Shock compression of two molded, carbon fiber-filled polymer composites was performed in gas gun-driven plate impact experiments at impact velocities up to ≈5 km/s. Hugoniot states for both composites were obtained from <5 GPa to nearly 50 GPa. The two materials contained a high fill percentage of chopped carbon fibers, bound by either phenolic or cyanate ester polymeric resins. Their dynamic responses were similar, although the 10 wt. % difference of carbon fill produced measureable divergence in shock compressibility. The chopped carbon fibers in the polymer matrix led to moderately anisotropic shocks, particularly when compared with the more commonly encountered filament-wound carbon fiber-epoxy composites. A discontinuity, or cusp, was observed in the principal Hugoniot of both materials near 25 GPa. We attribute the accompanying volume collapse to shock-driven chemical decomposition above this condition. Inert and reacted products equations of state were used to capture the response of the two materials below and above the cusp.

  13. Scalable Fabrication of Nanoporous Carbon Fiber Films as Bifunctional Catalytic Electrodes for Flexible Zn-Air Batteries.

    PubMed

    Liu, Qin; Wang, Yaobing; Dai, Liming; Yao, Jiannian

    2016-04-20

    A flexible nanoporous carbon-fiber film for wearable electronics is prepared by a facile and scalable method through pyrolysis of electrospun polyimide. It exhibits excellent bifunctional electrocatalytic activities for oxygen reduction and oxygen evolution. Flexible rechargeable zinc-air batteries based on the carbon-fiber film show high round-trip efficiency and mechanical stability.

  14. Electrochemical Stability of Carbon Fibers Compared to Metal Foils as Current Collectors for Lithium-Ion Batteries

    SciTech Connect

    Martha, Surendra K; Dudney, Nancy J; Kiggans, Jim; Nanda, Jagjit

    2012-01-01

    The electrochemical behaviors of highly conductive, fully-graphitic, semi-graphitic and non-graphitic carbon fibers were studied as the cathode current collectors of lithium batteries in standard electrolyte (alkyl carbonate/LiPF6) solutions and compared to bare aluminum (Al). All of these current collectors demonstrate a stable electrochemical behavior within the potential range of 2.5 to 5 V, due to passivation by surface films. Carbon fibers have comparable electrochemical stability of Al and may be used in place Al foil. While the carbon fibers do not contribute any irreversible or extra capacity when they are cycled below 4.5 V, for fully-graphitic and semi-graphitic fibers PF6 intercalation and deintercalation into the carbon fiber may occur when they are cycled at high potentials >4.5 V.

  15. Advances in electrospun carbon fiber-based electrochemical sensing platforms for bioanalytical applications.

    PubMed

    Mao, Xianwen; Tian, Wenda; Hatton, T Alan; Rutledge, Gregory C

    2016-02-01

    Electrochemical sensing is an efficient and inexpensive method for detection of a range of chemicals of biological, clinical, and environmental interest. Carbon materials-based electrodes are commonly employed for the development of electrochemical sensors because of their low cost, biocompatibility, and facile electron transfer kinetics. Electrospun carbon fibers (ECFs), prepared by electrospinning of a polymeric precursor and subsequent thermal treatment, have emerged as promising carbon systems for biosensing applications since the electrochemical properties of these carbon fibers can be easily modified by processing conditions and post-treatment. This review addresses recent progress in the use of ECFs for sensor fabrication and analyte detection. We focus on the modification strategies of ECFs and identification of the key components that impart the bioelectroanalytical activities, and point out the future challenges that must be addressed in order to advance the fundamental understanding of the ECF electrochemistry and to realize the practical applications of ECF-based sensing devices. PMID:26650731

  16. Advances in electrospun carbon fiber-based electrochemical sensing platforms for bioanalytical applications.

    PubMed

    Mao, Xianwen; Tian, Wenda; Hatton, T Alan; Rutledge, Gregory C

    2016-02-01

    Electrochemical sensing is an efficient and inexpensive method for detection of a range of chemicals of biological, clinical, and environmental interest. Carbon materials-based electrodes are commonly employed for the development of electrochemical sensors because of their low cost, biocompatibility, and facile electron transfer kinetics. Electrospun carbon fibers (ECFs), prepared by electrospinning of a polymeric precursor and subsequent thermal treatment, have emerged as promising carbon systems for biosensing applications since the electrochemical properties of these carbon fibers can be easily modified by processing conditions and post-treatment. This review addresses recent progress in the use of ECFs for sensor fabrication and analyte detection. We focus on the modification strategies of ECFs and identification of the key components that impart the bioelectroanalytical activities, and point out the future challenges that must be addressed in order to advance the fundamental understanding of the ECF electrochemistry and to realize the practical applications of ECF-based sensing devices.

  17. Clinical evaluation of carbon fiber reinforced carbon endodontic post, glass fiber reinforced post with cast post and core: A one year comparative clinical study

    PubMed Central

    Preethi, GA; Kala, M

    2008-01-01

    Aim: Restoring endodontically treated teeth is one of the major treatments provided by the dental practitioner. Selection and proper use of restorative materials continues to be a source of frustration for many clinicians. There is controversy surrounding the most suitable choice of restorative material and the placement method that will result in the highest probability of successful treatment. This clinical study compares two different varieties of fiber posts and one cast post and core in terms of mobility of crown margin under finger pressure, recurrent caries detected at the crown margin, fracture of the restoration, fracture of the root and periapical and periodontal pathology requiring crown removal over the period of 12months as evaluated by clinical and radiographical examination. Materials and Methods: 30 root canal treated, single rooted maxillary anterior teeth of 25 patients in the age range of 18–60 years where a post retained crown was indicated were selected for the study between January 2007 and August 2007; and prepared in a standard clinical manner. It was divided into 3 groups of 10 teeth in each group. After post space preparation, the Carbon fiber and Glass fiber reinforced posts were cemented with Scotch bond multipurpose plus bonding agent and RelyX adhesive resin cement in the first and second groups respectively. The Cast post and cores were cemented with Zinc Phosphate cement in the third group. Following post- cementation, the preparation was further refined and a rubber base impression was taken for metal-ceramic crowns which was cemented with Zinc Phosphate cement. A baseline periapical radiograph was taken once each crown was cemented. All patients were evaluated after one week (baseline), 3 months, 6 months and one year for following characteristics mobility of crown margin under finger pressure, recurrent caries detected at the crown margin, fracture of the restoration, fracture of the root and periapical and periodontal pathology

  18. Synthesis and characterization of vertically aligned carbon nanotube forest for solid state fiber spinning.

    PubMed

    Ryu, Seong Woo; Hwang, Jae Won; Hong, Soon Hyung

    2012-07-01

    Continuous carbon nanotubes (CNT) fibers were directly spun from a vertically aligned CNT forest grown by a plasma-enhanced chemical vapor deposition (PECVD) process. The correlation of the CNT structure with Fe catalyst coarsening, reaction time, and the CNTs bundling phenomenon was investigated. We controlled the diameters and walls of the CNTs and minimized the amorphous carbon deposition on the CNTs for favorable bundling and spinning of the CNT fibers. The CNT fibers were fabricated with an as-grown vertically aligned CNT forest by a PECVD process using nanocatalyst an Al2O3 buffer layer, followed by a dry spinning process. Well-aligned CNT fibers were successfully manufactured using a dry spinning process and a surface tension-based densification process by ethanol. The mechanical properties were characterized for the CNT fibers spun from different lengths of a vertically aligned CNT forest. Highly oriented CNT fibers from the dry spinning process were characterized with high strength, high modulus, and high electrical as well as thermal conductivities for possible application as ultralight, highly strong structural materials. Examples of structural materials include space elevator cables, artificial muscle, and armor material, while multifunctional materials include E-textile, touch panels, biosensors, and super capacitors. PMID:22966627

  19. Sharp burnout failure observed in high current-carrying double-walled carbon nanotube fibers.

    PubMed

    Song, Li; Toth, Geza; Wei, Jinquan; Liu, Zheng; Gao, Wei; Ci, Lijie; Vajtai, Robert; Endo, Morinobu; Ajayan, Pulickel M

    2012-01-13

    We report on the current-carrying capability and the high-current-induced thermal burnout failure modes of 5-20 μm diameter double-walled carbon nanotube (DWNT) fibers made by an improved dry-spinning method. It is found that the electrical conductivity and maximum current-carrying capability for these DWNT fibers can reach up to 5.9 × 10(5) S m(-1) and over 1 × 10(5) A cm(-2) in air. In comparison, we observed that standard carbon fiber tended to be oxidized and burnt out into cheese-like morphology when the maximum current was reached, while DWNT fiber showed a much slower breakdown behavior due to the gradual burnout in individual nanotubes. The electron microscopy observations further confirmed that the failure process of DWNT fibers occurs at localized positions, and while the individual nanotubes burn they also get aligned due to local high temperature and electrostatic field. In addition a finite element model was constructed to gain better understanding of the failure behavior of DWNT fibers. PMID:22156276

  20. Aspects regarding wearing behaviour in case of aluminium composite materials reinforced with carbon fibers

    NASA Astrophysics Data System (ADS)

    Caliman, R.

    2016-08-01

    This paper presents a study regarding wear comportment of sintered composite materials obtained by mixture of aluminium with short carbon fibers. The necessity to satisfying more and more the specific functions during design of high performance structures leads to perform multi-materials such as reinforced composite parts. The wear tests were made on three different orientations of fibers on a standard machine of tribology, pin disk type. Counter-disk was made of cast iron with a superficial hardness of 92 HB. The wear rate and friction coefficient decreased exponentially with time of friction and reached a stationary value. This behaviour was attributed to the development of a lubricating film on the friction surface. To conduct this work was performed measurements on samples from the Al matrix composites and carbon fiber 43%, wear mechanism was investigated by scanning electron microscopy. In addition to fiber orientation, the tribological behaviour of metal matrix composites reinforced with fiber is influenced by the interfacial reaction of fiber-matrix. The characteristics and the dimensions of the interface depend on the cycle of temperature and time at which the material has been subjected during the manufacturing process and thereafter.