Electromagnetic shielding materials play a significant role in solving the increasing environmental problem of electromagnetic pollutions. The commonly used metal‐based electromagnetic materials ...suffer from high density, poor corrosion resistance, and high processing cost. Polymer composites exhibit unique combined properties of lightweight, good shock absorption, and corrosion resistance. In this study, a novel high angle sensitive composite is fabricated by combining carbon fiber (CF) fabric with thermoplastic polyurethane elastomer (TPU). The effect of stacking angle of CF fabric on EMI shielding performance of composite is studied. When the stacking angle of CF fabric changed, the electromagnetic interference (EMI) shielding effectiveness (SE) of CF fabric/TPU composite can reach a maximum of 73 dB, and the tensile strength can reach 168 MPa. In addition, the composite has anisotropic conductivity, which is conductive along the plane direction and nonconductive along the thickness direction. Moreover, the CF fabric/TPU composite manifests exceptional EMI‐SE/density/thickness value of 383 dB cm2 g−1, which is higher than most of current EMI shielding composites reported in literature. In summary, CF fabric/TPU composite is an excellent EMI shielding material that is lightweight, highly flexible, and mechanically robust, which can be applied to the field of aerospace and some intelligent electronic devices.
This study presents a general, facile, and ecofriendly approach to prepare carbon fiber fabric/thermoplastic polyurethane elastomer (TPU) composites with different stacking layers and angles. The electromagnetic shielding performance of the lightweight carbon fiber (CF) fabric/TPU composite can be improved with the increase of stacking layers and stacking angles. The CF fabric/TPU composite also possesses excellent mechanical properties.
Electroactive shape memory polymers (SMPs) are suitable for remote controllable actuators or applications where direct heat is inconvenient, and herein an electroactive shape memory polyimide ...(EASMPI) is reported for the first time. EASMPI is synthesized by incorporating ground carbon fibers (GCFs) into a polyimide matrix to form a compact conductive network, and percolation threshold of 0.312 S m−1 meets the demands of both electroactive and shape memory effects. The glass transition temperature of 302 °C for EASMPI is much higher than that of other electroactive SMPs, and its shape recovery is activated effectively by a voltage of 15.87 V. Recovery stress is crucial for shape memory materials to output work, and EASMPI produces high recovery stress of 40.1 MPa. The possible mechanisms are discussed, and GCF mainly accounts for its electroactivity and recovery stress. EASMPI shows vast potential in practical applications with its electroactive shape memory effect and high recovery stress at high temperature.
An electroactive shape memory polyimide (EASMPI) is synthesized for the first time by incorporating ground carbon fibers in a polyimide matrix, and it exhibits the highest glass transition temperature of 302 °C among electroactive shape memory polymers (SMPs). EASMPI possesses recovery stress of 40.1 MPa, much higher than those of other SMPs reported until now.
In this article, modification of carbon fiber surface by carbon based nanofillers (multi‐walled carbon nanotubes CNT, carbon nanofibers, and multi‐layered graphene) has been achieved by ...electrophoretic deposition technique to improve its interfacial bonding with epoxy matrix, with a target to improve the mechanical performance of carbon fiber reinforced polymer composites. Flexural and short beam shear properties of the composites were studied at extreme temperature conditions; in‐situ cryo, room and elevated temperature (−196, 30, and 120°C respectively). Laminate reinforced with CNT grafted carbon fibers exhibited highest delamination resistance with maximum improvement in flexural strength as well as in inter‐laminar shear strength (ILSS) among all the carbon fiber reinforced epoxy (CE) composites at all in‐situ temperatures. CNT modified CE composite showed increment of 9% in flexural strength and 17.43% in ILSS when compared to that of unmodified CE composite at room temperature (30°C). Thermomechanical properties were investigated using dynamic mechanical analysis. Fractography was also carried out to study different modes of failure of the composites.
The preliminary evaluation is described of a new electro-thermal anti-icing/de-icing device for carbon fibre composite aerostructures. The heating element is an electro-conductive carbon-based ...textile (ECT) by Gorix. Electrical shorting between the structural carbon fibres and the ECT was mitigated by incorporating an insulating layer formed of glass fibre plies or a polymer film. A laboratory-based anti-icing and de-icing test program demonstrated that the film-insulated devices yielded better performance than the glssass fibre insulated ones. The heating capability after impact damage was maintained as long as the ECT fabric was not breached to the extent of causing electrical shorting. A modified structural scarf repair was shown to restore the heating capacity of a damaged specimen.
Mild direct coal liquefaction (autogenous pressure, no catalyst, no H2 gas) of Springfield coal in fluid catalytic cracking decant oil is shown to effectively produce coal extract precursors to ...spinnable mesophase pitch. This work demonstrates that the coal extract can be thermally treated to obtain mesophase pitch in a facile one-step process, bypassing the production of an intermediate isotropic pitch. Furthermore, the presence of 25 wt.% coal in the initial slurry can increase the yield to mesophase pitch nearly twofold and yield to carbon fiber by approximately 70%. The coal extract-derived mesophase pitch was melt-spun and heat treated to produce carbon fiber with graphitic texture, high modulus (>400 GPa) and tensile strength up to 943 MPa. Overall, this work demonstrates that coal can be effectively utilized to markedly amplify the mesophase pitch and carbon fiber yield from fluid catalytic cracking decant oil by relatively simple processing, while conserving utility as a precursor to high performance carbon fiber and potentially other high value graphitic products.
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•Mild direct coal liquefaction in decant oil was used to obtain a coal extract.•The coal extract was thermally converted to a spinnable mesophase pitch.•Coal utilization improved yield to mesophase pitch nearly twofold.•Coal extract-derived carbon fiber displayed high modulus (>400 GPa).•Coal utilization resulted in a ∼70 % increase in yield to carbon fiber.
Microwire and Utah-style neural recording arrays are the predominant devices used for cortical neural recording, but the implanted electrodes cause a significant adverse biological response and ...suffer from well-studied performance degradation. Recent work has demonstrated that carbon fiber electrodes do not elicit this same adverse response, but these existing designs are not practically scalable to hundreds or thousands of recording sites. We present technology that overcomes these issues while additionally providing fine electrode pitch for spatial oversampling.
We present a 32-channel carbon fiber monofilament-based intracortical neural recording array fabricated through a combination of bulk silicon microfabrication processing and microassembly. This device represents the first truly two-dimensional carbon fiber neural recording array. The density, channel count, and size scale of this array are enabled by an out-of-plane microassembly technique in which individual fibers are inserted through metallized and isotropically conductive adhesive-filled holes in an oxide-passivated microfabricated silicon substrate.
Five-micron diameter fibers are spaced at a pitch of 38 microns, four times denser than state of the art one-dimensional arrays. The fine diameter of the carbon fibers affords both minimal cross-section and nearly three orders of magnitude greater lateral compliance than standard tungsten microwires. Typical Formula: see text impedances are on the order of hundreds of kiloohms, and successful in vivo recording is demonstrated in the motor cortex of a rat. 22 total units are recorded on 20 channels, with unit SNR ranging from 1.4 to 8.0.
This is the highest density microwire-style electrode array to date, and this fabrication technique is scalable to a larger number of electrodes and allows for the potential future integration of microelectronics. Large-scale carbon fiber neural recording arrays are a promising technology for reducing the inflammatory response and increasing the information density, particularly in neural recording applications where microwire arrays are already used.
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•Development of isotropic and mesophase pitch by controlled heat treatment of parent coal tar pitch leads to increase in softening point of the precursor.•Stabilisation time, ...temperature and rate should be finely tuned as the radial variation in oxygen content in the fiber causes defects in further processing.•Pyrolysis of stabilized fiber determines the structural properties of the final carbon fiber product. Beyond 1200 °C, the graphitic structure gets formed along the fiber axis. Therefore, tensile, thermal and electrical properties increase with increase in pyrolysis temperature.•GPCF has a typical tensile strength in the range of 3500-4500 MPa and tensile modulus of 230-270 GPa. This are suitable for automotive applications.•Carbon fiber finds its major application in carbon composites manufacturing. Apart from that, activated carbon fiber is used in water treatment and many other areas. Some high end applications like medical material, energy storage material has also been explored.
This review focuses on recent development of technologies used for producing coal tar pitch-based carbon fiber along with its applications. In the first part, modification of coal tar pitch by different methods for obtaining the carbon fiber precursor was presented. In the second part, melt spinning process for producing the green fiber and subsequent post spinning stabilisation and pyrolysis process was described. The present review article shows that an extensive research on pitch modification has been done through heat treatment process. Development of isotropic and mesophase pitch by controlled low temperature pyrolysis of parent coal tar pitch leads to increase in softening point of the precursor, which is a vital parameter. This article is also evident that the stabilisation time, temperature and rate should be finely tuned to obtain fiber of desired properties. Carbonisation beyond 1200 °C seems to be sufficient for obtaining an ordered structure. All the possible applications of carbon fiber have been portrayed in the current review article. It was observed that the main application of carbon fiber is in the composite manufacturing sector. Starting from carbon-carbon composite to metal composites, carbon fiber found its major applications. Apart from that, activated carbon fiber had also been a topic of interest in the research domain.
In order to clarify the fracture behavior of a unidirectional CFRP under proportional loading along the fiber (0°) and fiber vertical (90°) directions, a biaxial tensile test was carried out using a ...cruciform specimen with two symmetric flat indentations in the thickness direction. Three fracture modes were observed in the specimens after the test. The first mode was a transverse crack (TC), and the second was fiber breakage (FB). The third mode was a mixture mode of TC and FB (TC&FB). According to the measured fracture strains, regardless of the magnitude of the normal strain in the 0° direction, TC and TC&FB modes occurred when the normal strain in the 90° direction, εy, ranged from 0.08% to 1.26% (positive values), and the FB mode occurred when εy ranged from -0.19% to -0.79% (negative values). The TC&FB mode is a unique mode that does not appear as a failure mode under uniaxial tension; it only occurs under biaxial tensile loading. Biaxial tensile tests were also conducted under non-proportional loading. The result showed three fracture modes similarly to the proportional loading case, each of which was also determined by the positive or negative value of εy. Thus, this study reveals that the occurrence of each fracture mode in a unidirectional CFRP is characterized by only one parameter, namely εy.
Synthesis of affordable electrocatalysts with high efficiency at low cost is crucial for large-scale water splitting. Molybdenum carbide (Mo2C) has been suggested to be a promising alternative to ...noble metal based electrocatalysts for water splitting. In this paper, we fabricated a nanotextured coating of wrinkled Ni-doped Mo2C on carbon fiber paper (CFP) from Ni, Mo and carbon black (CB) via a molten salt method. Such a novel electrocatalyst, denoted as Ni-Mo2CCB/CFP, shows an overpotential of 121.4, 209.3 and 426.4 mV to achieve a current density of 10, 20 and 50 mA cm−2 respectively in acidic medium. The hydrogen evolution reaction (HER) performance of other as-prepared CFP based electrodes (bare CFP, Mo2C/CFP, Mo2CCB/CFP, Ni-Mo2C/CFP and NiCx/CFP) also tested. We found that the addition of carbon black and the doping of Ni could significantly improve the electrocatalytic performance of Mo2C/CFP in terms of overpotential, Tafel slope and exchange current density. This work demonstrates a facile and scalable route using molten salt method for the synthesis of high-performance electrocatalysts from non-precious compounds on carbon materials.
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•Carbon fiber paper (CFP) was employed as a carbon source and substrate of Mo2C.•The addition of carbon black (CB) contributes to the refinement of Mo2C particles.•Ni-Mo2C/CFP composite was prepared from Ni, Mo, CFP and CB by a molten salt method.•The Ni-Mo2C/CFP electrocatalyst exhibits excellent catalytic performance for HER.
Graphene was used as an additive in fiber-reinforced plastics. The apparent interfacial shear strength (IFSS) was improved by grafting graphene onto the fibers. In this study, the effect of graphene ...grafted onto carbon fiber via chemical covalent bonding on the mechanical properties of the fibers was evaluated. This method was used to link graphene and carbon fibers via ester linkages, which are stronger than physical adsorption interactions and cause little damage to the fiber strength. Before grafting through an ester linkage, an electrophoretic deposition was conducted to uniformly coat graphene onto the carbon fibers. The purpose of this study was to establish a fabrication method that could control the density and thickness of the graphene layer covalently bound to the fibers. In addition, the optimal production process and composite form of the reinforced fibers were determined by evaluating the fiber strength and IFSS of various graphene-reinforced fibers. Ultimately, it was determined that graphene could be grafted onto carbon fibers relatively uniformly, and that the graphene layer thickness affected their interfacial shear strength. In terms of optimizing the IFSS, a thin and uniform graphene layer was best, and the IFSS was improved by 42.1% compared with untreated fibers containing sizing agents.
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•Graphene was composited onto carbon fiber via electrodeposition and covalent bonding.•It was suggested that an optimal amount of GO the fiber exists to improve the IFSS.•Graphene layer thickness on the fiber surface affected the interfacial shear strength.•The interfacial strength was enhanced without compromising the fiber strength.
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