Carbon Fiber Filament Research Articles

On the piezoresistive behavior of carbon fibers - Cantilever-based testing method and Maxwell-Garnett effective medium theory modeling

A good understanding of the piezoresistive behavior of carbon fiber is highly valuable in studying the processing-structure-property relationship of this very important engineering material. Up-to-date, there is still a lack of agreement on the physical origin of the unique modulus-dependent piezoresistivity for carbon fibers. In the present work, an experimental and theoretical modeling combined approach was taken to attack this long outstanding issue. A cantilever testing method was developed which allows for the evaluation of the piezoresistive behavior of a single carbon fiber filament under axial tension and compression mode. It was found that the tensile and compressive piezoresistive behavior showed antisymmetric characteristics. This supports the concept that the orientation of the basic structural units (BSUs) is responsible for the piezoresistivity of carbon fibers. Such an argument was further augmented by theoretical modeling of the carbon fiber piezoresistivity based on a Maxwell Garnett theory approach. The new piezoresistivity model identifies the critical role of the compound effect of the BSU orientation and its volume fraction in dictating the piezoresistive behavior of carbon fibers. With consideration of this compound effect, the modulus-dependent piezoresistivity data of carbon fibers reported in the past few decades can now be well explained.

Additive manufacturing of woven carbon fibre polymer composites

A novel technique for the fabrication of woven composites using additive manufacturing (AM) is presented and evaluated. To-date fibre reinforced composites deposited by AM exhibit highly anisotropic properties as the individual layers do not interact, this study helps address this by printing of a 0/90 woven structure into one layer to aid in stress distribution. A fibre path generator was created utilising Gcode to emulate the weft-warp components of a woven construction using a continuous carbon fibre filament. This new pathing technique also allows for a woven structure to be integrated with features (such as notches) previously only possible through destructive machining processes. In order to evaluate the performance of the printed composites, open hole tensile studies were carried out in which 6 mm holes were routed into the composite structure and the resulting part’s mechanical performance were compared with specimens which had been die punched as well as an unnotched control group. The latter exhibited strengths equivalent to 49% that of unnotched specimen. In contrast the specimens with woven holes exhibited strengths which were 44% higher, just 7% lower than the strength achieved for the unnotched specimens. Digital image correlation (DIC) analysis also demonstrated significantly reduced strain concentration around the printed hole perimeter, compared with that for the die punched hole.

Strength Characteristics of the Filaments and a Basalt Fiber Roving at Different Clamping Lengths and Deformation Rates

The strength properties of filaments and a basalt fiber roving of industrial production were investigated at different clamping lengths and deformation rates. The deformation rate for filaments was varied from 1 to 20 mm/min, but the clamping lengths selected were 10, 20, 30, and 50 mm. No clamping-length-dependence of strength parameters of the roving in the range of 350-600 mm was detected. The results found for basalt fiber filaments were compared with published data for Kevlar29 aramid, T300 carbon, and Advantex glass fiber filaments.

Carbon Fiber Electrodes for in Vivo Spinal Cord Recordings.

Development of micro electrode arrays for neural recording is an active field that thrives on novel materials and fabrication techniques offered by micro fabrication technology. The material and mechanical properties of microelectrode arrays have a critical role on the quality and longevity of neural signals. In this study, carbon fiber microelectrode (CFME) bundles were developed and implanted in the spinal cord of experimental animals for textbf{\textit{in vivo{recording. Neural data analysis revealed that single spikes could successfully be recorded and sorted. Removal of approximately $75 \mu \mathrm{m}$ of the parylene-C coating at the tips of the fibers increased the signalto-noise ratio. Connecting multiple (three) carbon fiber filaments to the same recording channel did not deteriorate the signal quality compared to that of undesheathed fibers. Immunohistochemistry showed that electrode tips were splayed in tissue after implantation and CF bundles had a small footprint with mild encapsulation around them. These results are very promising for the use of CFME bundles for recordings of spinal cord signals in behaving animals.

Electrical conductivity of unidirectional carbon fiber composites with epoxy-graphene matrix

This paper aims at establishing connections between electrical resistivity and stresses in carbon fiber reinforced epoxy-graphene composites. To avoid the interconnection of multiple parameters, we examined composite specimens consisting of a single strand or tow (12,000 carbon fiber filaments) embedded in an epoxy matrix containing up to 1.0 wt% of graphene (TG679) particles. The specimens show resistance increase with the tensile stress. The characteristic of the dependence varies with the content of graphene particles, tending to be linear as the percentage of graphene content increases. We did not observe any significant changes in the ultimate strength of the composite with an increase of the graphene particles concentration.

Preparation and characterization of open-cell epoxy foams modified with carbon fibers and aluminum powder

Epoxy foams were prepared by the sacrificial template method. The porous template was prepared from carbamide granules and then impregnated with epoxy resin. The method ensured foams with low relative density of 0.334–0.358 and an open-cell structure consisting of regular spherical cells and round interconnecting windows. Epoxy resin was modified with short carbon fibers and aluminum powder. Both fillers ensured the increase in compressive strength by 12–15% as compared to the neat epoxy foam. The carbon fiber filler ensured much higher specific strength (up to 18.5–18.6 MPa·cm3·g−1) due to little effect on the foam density. Sandwich composite samples were prepared using CPRF facing and the epoxy foam core, and promising mechanical properties of the sandwiches were stated by the 3-point midspan flexure test.

Prediction of degree of impregnation in thermoplastic unidirectional carbon fiber prepreg by multi-scale computational fluid dynamics

A multi-scale simulation approach was proposed to predict the degree of impregnation (DoI) in thermoplastic unidirectional carbon fiber prepreg (UD-CFP). The multi-scale approach included a two-dimensional (2D) micro-scale computational fluid dynamics (CFD) in a representative elementary volume (REV) of carbon fiber (CF) tow, a 3D macro-scale CFD of an entire impregnation die with 15 sliding CF tows, and a process-scale simulation assembling data from the micro- and macro-scale CFDs. In the macro-scale steady-state CFD, thermoplastic resin injection and CF tow insertion were considered for an impregnation die 10 cm in width. In the micro-scale transient CFD, impregnation mechanisms of resin into CF filaments 7 μm in diameter were identified in terms of surface coverage, capillary permeation, and penetration through CF filaments. The DoI as a function of pressure and time was obtained from the micro-scale CFD within a range of pressures found in the macro-scale CFD. In the process-scale simulation, the cumulative DoI of the 15 tows was predicted along the impregnation die length with the aid of the micro- and macro-scale CFD results. Combining the multi-scale models gives a potential to predict the uniformity of the transverse resin amount in the final UD-CFP product.

Improvement of out-of-plane thermal conductivity of composite laminate by electrostatic flocking

Increasing the out-of-plane thermal conductivity of polymer composite laminate is a challenge for applications that require heat dissipation. This paper adopted the electrostatic flocking method to embed different fillers in thin carbon fiber mat to produce a high thermal conductive ply, which was named fuzzy mat. The fuzzy mat was laminated alternatively with two-dimensional fabric to bridge the adjacent fabric plies. The effects of microstructure and structural parameters of fuzzy mat, as well as the filler type, on out-of-plane thermal conductivity were investigated. The results showed that the fuzzy mat effectively filled the resin rich area in the carbon fabric composite and greatly improved thermal conductivity. Pre-cured and double surface implanted fuzzy mat was beneficial for the construction of thermal conduction path. The out-of-plane thermal conductivities of the composite laminates increased as the content and length of pitch-based carbon fiber fillers increased. The thermal conductivity of composite laminate by introducing 10wt% fuzzy mat with 300- to 400-μm-long pitch-based carbon fiber filler was up to 1.2W/(m·K), which was 216% higher than the thermal conductivity of the control sample, which was 0.38W/(m·K). Moreover, the vapor-grown carbon fiber effectively improved both the out-of-plane thermal conductivity and the interlaminar shear strength.

3D Printing of Carbon Fiber Reinforced Plastics and their Applications

3D printing of carbon fiber reinforced plastics can produce lightweight components with higher efficiency and more complex structure. For the short carbon fiber reinforced plastics, the composites are firstly made by compounding, then they are processed to filaments, powders or other needed forms, finally the components are printed by Fused Deposition Modeling (FDM), Selected Laser Sintering (SLS) or other methods. The tensile strength of the nylon-based component is more than 70 MPa. Companies such as EOS, Stratasys and Farsoon can provide the materials and equipments. For the continuous carbon fiber reinforced plastics, the divided carbon fibers and plastic filaments or impregnated carbon fiber filaments are firstly prepared, then the components are printed by FDM or other methods. The average tensile strength of the nylon-based component is more than 200 MPa. Companies such as Markforged and Arevo Labs have commercialized the 3D printing equipment/platform for the continuous fiber reinforced plastics.

The Study of Thermal, Mechanical and Shape Memory Properties of Chopped Carbon Fiber-Reinforced TPI Shape Memory Polymer Composites.

Trans-l,4-polyisoprene (TPI) shape memory polymer composites with different chopped carbon fiber mass fractions were prepared to study the effects of different chopped carbon fiber mass fractions and temperatures on the TPI shape memory polymer composites in this paper. While guaranteeing the shape memory effect of TPI shape memory polymers, the carbon fiber fillers also significantly enhanced the mechanical properties of the polymers. The thermodynamic properties and shape memory properties of TPI shape memory polymers were studied by a differential scanning calorimeter (DSC) test, dynamic mechanical analysis (DMA) test, thermal conductivity test, static tensile test, mechanical cycle test, thermodynamic cycling test and shape memory test. Furthermore, the tensile fracture interface of TPI shape memory polymer composites was analyzed by scanning electron microscopy. The experimental results show that when the chopped carbon mass fraction fiber is 8%, TPI shape memory polymers have good shape memory properties and the best mechanical properties.

Properties of CF/PA6 friction spun hybrid yarns for textile reinforced thermoplastic composites

Due to their excellent strength, rigidity and damping properties as well as low weight, carbon fibre reinforced composites (CFRC) are widely being used for load bearing structures. On the other hand, with an increased demand und usage of CFRCs, effective methods to re-use waste carbon fibre (CF) materials, which are recoverable either from the process scraps or from the end-of-life components are attracting increased attention. In this paper, hybrid yarns consisting of staple CF and polyamide 6 (PA 6) are manufactured on a DREF-3000 friction spinning machine with various machine parameters such as spinning drum speed and suction air pressure. The relationship between different textile physical properties of the hybrid yarns, such as tensile strength and elongation with different spinning parameters and CF content of hybrid yarn is investigated. Furthermore, the tensile properties of uni-directional (UD) composites manufactured from the developed hybrid yarn shows 80% of the UD composite strength made from CF filament yarn.

Concrete Filled Carbon FRP Tube (CFRP-CFFT) columns with and without CFRP reinforcing bars: Axial-flexural interactions

Abstract The axial and flexural behaviors of Concrete Filled Carbon Fiber Reinforced Polymer Tube (CFRP-CFFT) columns have received significant research attention in the last two decades. One of the most attractive advantages of Carbon FRP (CFRP) tube is the high confinement which results in substantial increase in peak axial and flexural loads and deformations. Despite large research efforts, the behavior of CFRP-CFFT with and without CFRP reinforcing bars under different applied axial load eccentricity has not yet been adequately investigated. This study investigates the experimental and analytical axial-flexural ( P − M ) interactions of CFRP-CFFT columns with and without CFRP reinforcing bars. A total of 12 specimens of 204–205 mm outer diameter and 800–812 mm height were tested under concentric axial load, 25 mm and 50 mm eccentric axial loads and four-point load. The effectiveness of CFRP reinforcement (tube and bar) was observed to be reduced with the increase in the applied axial load eccentricity. Analytical P − M interactions were constructed using available FRP confined concrete design codes which matched well with the experimental P − M interactions. The parametric study showed that the actual confinement ratio, orientation of fibers and CFRP bar reinforcement ratio have significant influences on P − M interactions of CFRP-CFFT specimens.

Strengthening of plasma treated 3D printed ABS through epoxy infiltration

3D printed fused deposition modeling (FDM) material parts have distinct anisotropic mechanical properties based upon their as-built print orientation. The strength of material printed perpendicular to the deposition layers can be as low as 50% of values for injection molded parts due to less than optimum interlayer fusion, limiting their use for critical applications. The focus of this work is to present a novel way of utilizing design freedoms available in FDM to improve strength in weak orientations. Vertically processed FDM ABS parts were manufactured with cavities printed perpendicular to the interlayer direction and were subsequently plasma surface treated, filled with an epoxy resin, and mechanically tested. Plasma treatment was shown to beneficially modify the surface chemistry, which resulted in a 50% improvement in shear strength over untreated specimens. Samples that underwent plasma treatment and epoxy infiltration demonstrated a 130% increase in flexural strength over that of as-printed FDM material. The failure strain was also shown to increase by two-fold. The addition of milled carbon fiber (MCF) filler within the epoxy infiltrate was also evaluated and was shown to increase the flexural modulus by as much as 76% at 10 wt% loading levels, though negligible increases in strength were observed.

Improved mechanical properties of PMMA composites: Dispersion, diffusion and surface adhesion of recycled carbon fiber fillers from CFRP with adsorbed particulate PMMA

In this study, composite materials were fabricated using the thermoplastic resin poly(methyl methacrylate) (PMMA) and recycled carbon fibers obtained by pulverizing carbon fiber reinforced plastics (CFRP). PMMA particles were adsorbed on the carbon fiber surfaces via electrostatic interactions, to promote the interfacial adhesion between the carbon fibers and the PMMA resin and thereby improve the dispersion of the fibers in the resin. This enhanced the mechanical properties of the composites; the yield stress and elastic modulus of the composite. As a result, the yield stress and elastic modulus of the composite improved owing to the prevention of void formation in the composite resulting from the chemical incompatibility between the filler and the resin and better dispersion of the PMMA-adsorbed carbon fibers in the resin compared to that in the unmodified fibers. This method can be applied to fabricate high-quality composites consisting of a combination of other resins and fillers.

Composite materials for impellers of the turbocharger of automotive engines

The aim of this work is the search and selection of components of composite materials are fully meeting the requirements imposed to the materials of the impellers of the turbocharger. During the work modern components of the composites and their properties is described. The requirements to materials of impellers were formulated. Patent search was carried out to describe existing concepts of impellers made of composite materials. A possible production version of the impellers is described, revealed their advantages and disadvantages. In the course of patent studies have not traditional the advantages of using composites in the design of the turbocharger. Described the possibility of creating a rotor of the electric machine of the compressor impeller by weaving a copper wire. The main technology of manufacture of impellers is described. Given domestic and foreign manufacturers of polymer matrixes and fibers. The described physic-mechanical properties of randomly reinforced composite materials available on the market today. A comparative analysis of selected composite material most fully meets the requirements - polyamideimide filled carbon fiber. The use of continuous fibers in the impellers is an effective way to increase the strength of the latter. It is established that as a cheaper alternative to polyamideimide can be a carbon-containing material '^^11!" provided reinforcement of the wheel with continuous fibers. Cheap and widely used materials (filled polyamides, polycarbonates, epoxy resin, etc.) can be used in the manufacture of impellers in centrifugal blowers with manual or electric drive. Composites with carbon fiber in silicon carbide matrix (C-SiC) can act as an alternative to heat-resistant nickel alloys, of which currently produce the turbine wheel.

Mechanical properties of the compositions based on biopolyamide-1010 modified by carbon, glass, and cellulose chopped fibers

The influence of chopped cellulose, carbon, and glass fiber fillers on the physicomechanical properties of biopolyamide-1010-based compositions is studied. The properties of the composites filled with carbon fibers are shown to be improved when a combination of carbon fibers with short cellulose fibers is used.

Friction and wear characteristics of ultrahigh molecular weight polyethylene (UHMWPE) composites containing glass fibers and carbon fibers under dry and water-lubricated conditions

The effects of introducing glass fiber (GF) and/or carbon fiber (CF) filler materials on the friction and wear characteristics of ultra-high molecular weight polyethylene (UHMWPE)-based composites were investigated. The composites were evaluated against GCr15 steel under dry and water-lubricated conditions. The goal was to develop an improved material for water-lubricated journal bearings. The friction coefficients of UHMWPE composites were obtained using a pin-on-disc tribometer using sliding speeds ranging from 0.2 to 1.0m/s, contact pressures from 1.0 to 5.0MPa, and two counterface roughness values (Ra=0.1 and 0.3μm). The samples were lubricated by dropping distilled water onto the sliding surface. To evaluate the wear mechanisms, the morphologies of the worn surfaces were examined by scanning electron microscopy and laser 3D micro-imaging profile measurements. In addition, the elemental distribution and content in the transfer film on the GF/UHMWPE composite surface were measured using an energy-dispersive X-ray spectrometer. The results show that glass fibers could effectively reduce the wear rate of composites. In addition, a hybrid filling of glass and carbon fibers could significantly reduce the friction coefficient under water lubrication and dry conditions.

An efficient microbial fuel cell using a CNT–RTIL based nanocomposite

A woven carbon fiber filament coated with a nanocomposite consisting of amine functionalized multi-walled carbon nanotubes and a room temperature ionic liquid was used as the anode and cathode.

Decoration of zinc oxide nanoparticles onto carbon fibers as composite filaments for infrared heaters

This study examines the thermal properties of ZnO-coated carbon fiber (CF) filaments for high-performance infrared (IR) heaters. An efficient pulse microwave (PM) method is applied to deposit different morphologies of ZnO crystals at various pH values of Zn2+ solutions, i.e., fragments (pH=9), thin films (pH=10), bulky islands (pH=11), and nanoparticles (pH=12). Under the applied voltage of 25V, the CF composite filament, prepared by the PM route at pH=10, offers the highest thermal radiation power and superior heat-storage capability among these IR heaters. Its saturation temperature and heating rate of ZnO-coated CF heater can reach to 184°C and 28°C/min, respectively. The enhanced thermal performance can be ascribed to the facts (i) the ZnO crystals create more emissive surface area and (ii) the composite filament illuminate more homogeneous spectral IR rays, showing the synergetic effect.

Recycling and remanufacturing of 3D printed continuous carbon fiber reinforced PLA composites

A cleaner production pattern for high-performance continuous carbon fiber reinforced thermoplastic composites (CFRTPCs) has been proposed on the base of recycling and remanufacturing of 3D printed continuous carbon fiber reinforced (CFR) PLA composites. Continuous carbon fiber and PLA matrix was recycled in the form of PLA impregnated carbon fiber filament from 3D printed composite components and reused as the raw material for further 3D printing process. The original printing trajectory is reversely applied, allowing for a 100% recycling of the continuous fiber without any effect on the mechanical properties. Tensile performance of recycled carbon fiber filaments was evaluated, which was higher than that of originally printed composites. Remanufactured CFRTPCs specimens also exhibited a 25% higher bending strength than that of original ones, which experimentally demonstrated the first non-downgrade recycling process for CFRTPCs. A material recovery rate of 100% for continuous carbon fiber and 73% for PLA matrix were achieved for a better environmental impact. Energy consumption of 67.7 and 66 MJ/kg respectively for recycling and remanufacturing processes was detected and compared with conventional methods. The proposed cleaner production pattern offered a potential strategy for the low-cost industrial application of fully recyclable composites.