Carbon Fiber Textiles Research Articles

Dumbbell-shaped mixed bimetallic-oxides decorated on carbon-fiber textile for high-performance flexible symmetric solid-state pseudocapacitors

A novel dumbbell-shaped mixed bimetallic oxide (Ni1.71Co1.29O4) is directly anchored on activated carbon fiber textile (CFT) for high-performance flexible symmetric supercapacitors (NCO@CFT-FSSCs). The as-fabricated NCO@CFT-FSSC exhibits excellent supercapacitive performance by achieving the high-specific capacity of 200 mAh/g at 1 A/g with excellent rate capability of 71% at 10-folded high current density. The NCO@CFT-FSSC showed outstanding cycling stability over 5000 cycles by retaining 94.78% capacity at a current density of 12.5 A/g. Moreover, the NCO@CFT-FSSC possesses good flexible performance and maintained 89.64% capacity over 500 bending cycles. Therefore, the achieved fascinating charge storage capabilities along with excellent flexibility ensure that Ni1.71Co1.29O4 being a potential material for high-performance supercapacitors.

Tensile Behaviors of Lap-Spliced Carbon Fiber-Textile Reinforced Mortar Composites Exposed to High Temperature

The tensile behaviors of textile-reinforced mortar (TRM) composites made with carbon fiber textile and alumina cement-based mortar were investigated through direct tensile tests. Three different surface treatment details in the lap splice area were used to improve the tensile behaviors of the TRM composites: carbon fiber textile impregnated by epoxy, carbon fiber textile coated with aluminum oxide powder following epoxy impregnation, and carbon fiber textile coated with aluminum oxide powder following both carbon fiber fabric attachment and epoxy impregnation. Three different lap splice lengths were used 180, 200, and 220 mm. In addition, the tensile properties of TRM composites following exposure to high temperature were investigated as well. In this test, TRM test specimens were exposed to two different temperature histories with maximum values of 250 and 350 °C. The results of the test specimens according to the test parameters were analyzed in terms of initial stiffness, cracking strength, corresponding strain at cracking, modulus of elasticity in the cracked stage, peak strength, and ultimate strain. The influence of lap splice length on the tensile behaviors of the TRM composites was analyzed and discussed. The surface treatment in the overlapping region showed ductile behavior and resulted in a significant improvement of the peak strength and ultimate strain over the untreated lap splice textile. Following exposure to high temperature, the TRM composites showed a reduction of tensile responses compared to those cured at room temperature. In addition, a prediction model developed in the previous study was used to predict the tensile behaviors of the lap-spliced carbon fiber-textile reinforced mortar composites exposed to high temperature, and the prediction by the model showed a good agreement with the experimental results.

Experimental study on carbon fiber textile reinforced mortar system as a means for confinement of masonry columns

Abstract The present paper demonstrates the results of an experimental and analytical research programme on masonry structures confined with Textile Reinforced Mortars (TRMs). A total of 39 small scale masonry columns were subjected to uniaxial compression tests after being strengthened with TRM layers. The variables studied during the experiments were, the number of TRM layers, the cross-section aspect ratio and the corner radii. The purpose of this experimental investigation was to examine the influence of the aforementioned parameters on the performance of confined masonry. In general, the TRM jackets increased substantially both the strength and the ductility of the confined specimens. The results obtained from the current experimental study allowed the development of a simple set of equations, using a linear and a non-linear approach, for the prediction of the strength and the ultimate strain of TRM-confined masonry. The non-linear approach gives a better approximation for the prediction of the compressive strength, and the relevant strain. Further experimental investigation is needed in the future to include more types of fibers, textiles, mortars, and masonry materials.

Evaluation of nitrogen- and sulfur-doped porous carbon textiles as electrode materials for flexible supercapacitors

With an objective to increase an electrochemical performance, simple and effective modifications of activated carbon fiber textiles (ACT) were carried out prior to their testing as supercapacitors. The modifications included a high-temperature treatment of the textile impregnated with N- and S-containing species (i.e. dicyandiamide, urea and thiourea). This led to an improvement in an electrical conductivity and in an enhanced mechanical strength with a preserved porosity. Compared to the performance of the initial unmodified carbon textile, a urea-functionalized material showed an enhancement in the electrochemical capacitance. An increase from 177 to 209 F g−1 at a scan rate 10 mV s−1 in an alkaline electrolyte was recorded (3-cell CV measurements) and from 138 to 166 F g−1 at 0.10 A g−1 (2-cell galvanostatic charge-discharge). The results suggested that mechanically stable, flexible and conductive ACT have a potential to be used in textile-based flexible supercapacitors. Benefits coming from the applied modification routes can be also adapted for the fabrication of other types of carbon-based composite electrode materials.

Autonomous preforming system: automated and sensor-aided handling of dry carbon fibre textiles

Preforming of carbon fibre reinforced plastic (CFRP) parts is one of the most difficult and time consuming manufacturing processes for large aircraft structures. The main challenges are the handling and draping of flexible fabrics into complex curved geometries to achieve the defined fibre angles which are mandatory for the required mechanical properties of the part. At the Centre for Lightweight Production Technology (ZLP) of the German Aerospace Centre (DLR) in Augsburg automation solutions for such manufacturing processes of full scale aircraft structures are developed.This paper presents an approach for a dynamic patch preforming method for dry carbon fibre textiles. The goal was the automation of the process with focus on digitalization. To identify essential automation steps the process chain was analyzed and described. The automation for the dynamic preforming was established with an industrial robot cell and a mechanical end effector. The end effector is capable of deforming to fit complex curvatures and handling of cut pieces regarding the draping simulations. A digitalized model of the end effector was used to simulate its deformation. Furthermore the detection, autonomous handling and movement monitoring of cut pieces is explained. Finally an automated process for a full scale Rear Pressure Bulkhead (RPB) patch preforming was set up and realized.

Enhancing the Capacitive Storage Performance of Carbon Fiber Textile by Surface and Structural Modulation for Advanced Flexible Asymmetric Supercapacitors

AbstractThe exploration of high‐energy anodes with good mechanical properties is highly attractive for flexible asymmetric supercapacitors (ASCs) but challenging. Owing to the excellent conductivity and superior mechanical flexibility, carbon fiber textile (CFT) holds great promise as a substrate/current‐collector for fabricating flexible electrodes. Yet, it is rarely used as a flexible active electrode in terms of its low electrochemical reactivity and small accessible area. In this work, an effective surface and structural modulation strategy is developed to directly tune CFT into a highly active anode for flexible ASCs by creating hierarchical pores and numerous pseudocapacitive oxygenic groups. Arising from large surface and increased active sites, the as‐prepared activated porous CFT (APCFT) electrode not only achieves a large capacitance (1.2 F cm−2 at 4 mA cm−2) and fast kinetics but also shows satisfying cycling durability (no capacitance decay after 25 000 cycles). More importantly, an advanced flexible ASC device with an impressive energy density of 4.70 mWh cm−3 is successfully assembled by employing this APCFT as an anode, outperforming most recently reported ASC devices. This dual modification strategy may throw light on the rational design of new generation advanced carbon electrodes for high‐performance flexible supercapacitors.

Experimental and analytical investigations on sustainable and innovative strengthening systems for masonry arches

The paper deals with the structural behaviour of masonry arches strengthened through fibre reinforced composites with inorganic matrix (Textile Reinforced Mortar, TRM). Two innovative composites are considered: basalt fibre textile coupled with a lime-based matrix and carbon fibre textile associated with a cement-based matrix. Experimental results on bond capacity between composites and bricks and on the structural behaviour of unreinforced and extrados-reinforced, 1:2 scale masonry arches, tested under vertical load are presented. Experimental evidence is compared with outcomes obtained through an analytical model that exploits the stationarity of potential energy of acting forces within the assumption of large displacements. The effect of the reinforcement strip is taken into account retrieving the force-displacement relationship directly from experimental results of bond test. Results show that the analytical model provides a safety estimation of the peak load reached by the arch model during the test. Good agreement is found comparing the load-displacement diagram of the initial phases of the test and the estimations of the numerical model. It is highlighted that the bond force of TRM systems, experimentally determined on a straight substrate, offers capacity levels relevantly under those reached on a convex surface like the extrados of an arch.

Degradation and Mineralization of Carbamazepine Using an Electro-Fenton Reaction Catalyzed by Magnetite Nanoparticles Fixed on an Electrocatalytic Carbon Fiber Textile Cathode.

Pharmaceutical wastes are considered to be important pollutants even at low concentrations. In this regard, carbamazepine has received significant attention due to its negative effect on both ecosystem and human health. However, the need for acidic conditions severely hinders the use of conventional Fenton reagent reactions for the control and elimination of carbamazepine in wastewater effluents and drinking water influents. Herein, we report of the synthesis and use of flexible bifunctional nanoelectrocatalytic textile materials, Fe3O4-NP@CNF, for the effective degradation and complete mineralization of carbamazepine in water. The nonwoven porous structure of the composite binder-free Fe3O4-NP@CNF textile is used to generate H2O2 on the carbon nanofiber (CNF) substrate by O2 reduction. In addition, ·OH radical is generated on the surface of the bonded Fe3O4 nanoparticles (NPs) at low applied potentials (−0.345 V). The Fe3O4-NPs are covalently bonded to the CNF textile support with a high degree of dispersion throughout the fiber matrix. The dispersion of the nanosized catalysts results in a higher catalytic reactivity than existing electro-Fenton systems. For example, the newly synthesized Fe3O4-NPs system uses an Fe loading that is 2 orders of magnitude less than existing electro-Fenton systems, coupled with a current efficiency that is higher than electrolysis using a boron-doped diamond electrode. Our test results show that this process can remove carbamazepine with high pseudo-first-order rate constants (e.g., 6.85 h–1) and minimal energy consumption (0.239 kW·h/g carbamazepine). This combination leads to an efficient and sustainable electro-Fenton process.

A layered-wise, composite modelling approach for fibre textile reinforced cementitious composites

Textile Reinforced Cements (TRCs) offer an adequate alternative to more conventional building systems in construction due to their tunable and lightweight geometries. TRCs are currently either modelled by means of a discrete approach, where the textiles and the matrix are modelled separately, or by means of a smeared approach that averages the material's mechanical response over the cross-section.The research presented in this paper proposes a new, layered-wise approach of modelling where the through-thickness response of the composite is subdivided in different layers with individual mechanical properties. A tensile experimental campaign on different combinations of TRC layups, combining both glass and carbon fibre textiles, is performed and used as an input for the layered-wise numerical model. The model is then validated by comparison with flexural experiments performed on four different TRC layup combinations. The good agreement witnessed between the numerical predictions and the experimental results validates the layered-wise modelling approach proposed in this paper.

Mechanical modelling of a sheared textile composite unit cell

Composites made using carbon fibre textile reinforcement give an anisotropic material with directional mechanical properties that are dependent on the fabric architecture. The directional properties of a 2D textile are primarily based on weave pattern: The direction of warp and weft yarns, undulation of the tows, and the change in fibre orientation during dry fabric forming process.During dry fabric forming processes, shear is the dominant deformation mechanism as the 2D fabric conforms to 3D shapes. As the fabric changes its shape to match that of the tool, the fibres rotate away from the orthogonal axes as a function of the shear angle. The modified fibre orientation is carried through the curing process and ends up in the finished composite component. This has an influence on the mechanical properties of a cured composite in localised regions of high deformation. Currently the effect of shear during fabric forming is not usually taken into account when modelling the performance of the finished composite at the macro-scale. Through the development of a novel, robust virtual tool, it is possible to identify the change in mechanical properties for a given shear angle. This will allow the macro FE models to give more accurate results. High deformation regions can be identified from a forming simulation (e.g. a sheet of fabric draped over a tetrahedron tool and causes severe shear near the intrusion) and the change in mechanical properties of these local regions can be adjusted accordingly.Using the digital element method previously developed in University of Bristol, the dry fabric architecture can be accurately predicted. The current work has created the ability to shear this virtual unit cell to update the unit cell geometry. This deformed woven geometry is then mapped onto a sheared voxel mesh and combined with an epoxy resin matrix to obtain the meso-scale Representative Volume Element (RVE) model. By applying periodic load cases to the model, the stiffness matrix and therefore the mechanical properties of the composite can be determined. This tool is applicable for any 2D woven resin-infused composite.

Reactions

OPINION Reactions ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2018, 96 (19), p 5May 7, 2018Cite this:C&EN 96, 19, 5Letters to the editor Recycling renewables My colleagues and I at the University of Massachusetts, Lowell, appreciated the April 9 cover story titled “Recycling Renewables” (page 34), which raises what we agree are critical issues related to sustainable energy generation. Such issues have inspired numerous research efforts aimed at improving the situation, our own included.Specific to wind energy and with the benefit of support from the National Science Foundation (award 1230884), we set out to address the issue of sustainable wind turbine blade production from start to finish. In order to accomplish this, we focused on the creation of inexpensive, high-performance biobased epoxy resins from readily available components and successfully converted them to composites and confirmed that their properties were appropriate for such applications—thus addressing creation and use. In parallel, we further developed mechanical and chemical recycling strategies based on vitrimer formation—thus addressing end-of-life issues. Finally, our team applied life-cycle analysis to assess the impact of our strategies and identify challenges and opportunities in this space.This has resulted in three recent papers (Ind. Eng. Chem. Res. 2017, DOI: 10.1021/acs.iecr.6b03919, 10.1021/acs.iecr.6b03825, and 10.1021/acs.iecr.6b03829), with additional submissions planned. While not perfect (higher curing temperatures are needed versus conventional materials), the combination of high performance with reductions in materials costs and infusion times versus conventional systems offers clear potential for further development, especially when coupled with the recovery and reinfusion of high-value carbon fiber textiles (all demonstrated during the course of our efforts).Finally, I would like to highlight the fact that this effort would not have gotten off the ground without seed funding from the Massachusetts Toxics Use Reduction Institute (TURI), nor would we have progressed nearly as far without the assistance of numerous contacts in industry. Related to thermosets, my group has had help in some form from ACS Technical Products, Air Products, AkzoNobel, BASF, Bayer MaterialScience/Covestro, Broadview, CVC Thermoset/Emerald Performance Materials, Dixie Chemical, Huntsman, King Industries, Leepoxy, Momentive/Hexion, Perstorp, Reaxis, Sartomer, and TPI Composites, to name just a few—as well as repeated support from TURI as one of the very few sources of funding for applied research.Such support deserves recognition; indeed, we will not solve real-world problems without it. We very much hope to see others in both academia and industry working to build knowledge and solutions in this domain and hope that our own efforts will serve as useful contributions to the resolution of some of these issues.Daniel SchmidtLowell, Mass.

An Improved Scanning Strategy for Long Pulsed Laser Drilling of Carbon Fiber Textiles

An Improved Scanning Strategy for Long Pulsed Laser Drilling of Carbon Fiber Textiles

Quasi-static and fatigue performance of carbon fibre reinforced highly polymerized thermoplastic epoxy

Abstract The experimental investigation aimed to understand the effect of the weight-average molecular weight of thermoplastic epoxy matrix on the quasi-static and fatigue properties of carbon fibre textile reinforced composites. The first part is dedicated to the assessment of the effect on the fibre and matrix adhesion by three scale measurements: single fibre and matrix (micro scale); single yarn and matrix (meso scale); laminate (macro scale). The positive effects at macro scale of the highly polymerised matrix are detailed in the second part considering quasi-static and fatigue tensile loadings. The composite with highly polymerised thermoplastic epoxy matrix showed an improvement of the tensile strength, a better capacity to uniformly distribute the stress/strain state and a considerable enhancement of the fatigue life.

Mechanical characterization of integral aluminum-FRP-structures produced by high pressure die-casting

Due to the growing demand for light-weight solutions in a wide range of industrial sectors, the selection and combination of different materials is becoming more and more important. As a result, there is an increasing need for suitable joining technologies. In a new joining process, flexible glass fiber textiles are integrated into aluminum by high pressure die casting in the first production step. These structures are used for the electrochemical insulation between aluminum and carbon fiber textiles, which are connected in the subsequent production step by textile technology. The finished compound is formed in a final resin impregnation process. Challenges faced by Fraunhofer IFAM lie in the positioning, pre-tensioning, and infiltration of the glass fiber textiles in the high pressure die-casting process. The advantage of this joining technology, in addition to the electrochemical insulation between aluminum and carbon fibers, is in a slim and light-weight connection. Therefore, no thickening of the individual joining partners is necessary, and the force flow lines are not deflected. Within mechanical investigations of those hybrid structures it was determined, that the infiltration content of aluminum has only a small influence on the achievable tensile strength. Rather, casting parameters such as the holding pressure have an influence. The subsequent resin infusion process enables an additional infiltration by the resin system of fiber bundles that have been only slightly infiltrated with aluminum. As a result, additional adhesion can be achieved and the infiltration gaps can be closed. Furthermore, an influence on the achievable tensile strength was observed regarding the use of the fiber material. Further increases in tensile strengths were also observed by adapting the textile parameters (e.g. reduction of the fiber undulations). A variety of failure behaviors could be observed in dependence on textile and process parameters. Tensile strength of the hybrid structures was compared to reference samples made of glass fiber reinforced epoxy resin, to determine the loss of strength caused by the joining technology. Further investigations were carried out, including a fracture surface analysis using a scanning electron microscope. Thus it was possible to determine mechanisms of adhesion between encapsulated glass fibers and the surrounding aluminum matrix.

Nonlinear stress analysis of v-notched aluminum plates repaired with the wet patch technique

ABSTRACTIn this study, V-notched aluminum plates were repaired using the wet patch technique. Two different repair operations, single-side and double-side composite patches, were applied to the notched plates. Four layers of woven carbon fiber textile and with the same reinforcement angle were used as a composite patch. Previously, the epoxy was saturated onto the prepared carbon fiber textiles and glued to the plates, and then those plates were placed in a vacuum medium. The repaired plates were experimentally tested under tension load. A nonlinear stress analysis was carried out using the finite element methodology in addition to the experimental results. As major foci of the study, the effects of repair type and notch size on failure behavior and plastic stress distribution were examined. As a result, it was found that the notch depth affects the repair performance far more than the notch width. Debonding failure load between the patch and the plate in plates repaired with a single-side patch was found to be two times higher than the yield load. For the double-side patch, the yield load was close to the debonding load and this repair method increases the debonding load more than a single-side patch.

Direct growth of CuCo2S4 nanosheets on carbon fiber textile with enhanced electrochemical pseudocapacitive properties and electrocatalytic properties towards glucose oxidation

Flexible and wearable electronic devices with excellent performance have been desired for making the next generation of electronic products. Herein, the synthesis of CuCo2S4 nanosheets on flexible carbon fiber textile (CFT) by a facile one-step and scalable hydrothermal procedure is reported, which is free from the sulphurization process used in the conventional synthesis of mixed metal sulphospinels. The as-prepared CuCo2S4 nanostructures on CFT can provide rich reaction sites and short ion diffusion paths. The CuCo2S4 nanosheets are employed as the free-standing electrodes for two different applications: high-performance supercapacitors and non-enzymatic glucose sensors. When employed as a flexible electrode material for supercapacitors, the electrode presents ultrahigh performance in energy storage with a specific capacitance of 3321.6 F g-1 at 5 A g-1, which is attributed to the suitable mass loading and special morphology of the as-prepared nanosheets. Remarkably, a specific capacitance of 2931.4 F g-1 is still retained at the high current density of 30 A g-1, suggesting its excellent rate capability. The specific capacitance retains 87.1% after 3000 cycles, reflecting excellent cycling performance. For real applications, a flexible symmetric supercapacitor is assembled based on CuCo2S4 nanosheets, which achieves a high energy density of 64.6 W h kg-1 at 499.7 W kg-1 and a maximum power density of 2081.5 W kg-1 at 45.1 W h kg-1. Besides serving as a free-standing electrode for non-enzymatic glucose sensors, CuCo2S4 nanosheets have remarkable electrocatalytic activity towards glucose oxidation with a high sensitivity of 3852.7 μA mM-1 cm-2 and an extraordinary linear range up to 3.67 mM. The experimental results suggest that CuCo2S4 nanosheets are more suitable for non-enzymatic glucose sensors than the related single/binary transition metal oxides/sulfides. Such a superior performance demonstrates that CuCo2S4 nanosheets hold great potential for use as flexible multifunctional electronic devices including supercapacitors and non-enzymatic glucose sensors.

Analysis of a bio-electrochemical reactor containing carbon fiber textiles for the anaerobic digestion of tomato plant residues

A bio-electrochemical system packed with supporting material can promote anaerobic digestion for several types of organic waste. To expand the target organic matters of a BES, tomato plant residues (TPRs), generated year-round as agricultural and cellulosic waste, were treated using three methanogenic reactors: a continuous stirred tank reactor (CSTR), a carbon fiber textile (CFT) reactor, and a bio-electrochemical reactor (BER) including CFT with electrochemical regulation (BER + CFT). CFT had positive effects on methane fermentation and methanogen abundance. The microbial population stimulated by electrochemical regulation, including hydrogenotrophic methanogens, cellulose-degrading bacteria, and acetate-degrading bacteria, suppressed acetate accumulation, as evidenced by the low acetate concentration in the suspended fraction in the BER + CFT. These results indicated that the microbial community in the BER + CFT facilitated the efficient decomposition of TPR and its intermediates such as acetate to methane.

Non-destructive infrared inspection of dry multilayer carbon fibre preforms

Thermography was used for performing non-destructive inspection of dry carbon fibre textile preforms used in manufacturing carbon fibre polymer-matrix composites (CF-PMCs). The aim was to probe the feasibility of identifying defects in thick carbon fibres preforms made from multiple layers of industrial textile reinforcements, before composites are manufactured. Inspecting dry preforms will not replace the inspection of final CF-PMC parts but it can avoid costly and wasteful manufacturing of CF-PMC parts from defective preforms, as the defects sought in this paper cannot be observed by visual inspection. The preforms tested were made of two or four layers of industrial carbon fibre textile reinforcements. They featured defects of different widths, types and orientations. Results show that thermography can identify defects in preforms successfully, and that detection is influenced by the orthotropic thermal conductivity of carbon fibres, by yarn and fabric architecture, by the relative orientations of defects and yarns, and by the number of layers.

Development of a High Pressure Die Casting Tool for Partial Integration of Glass Fiber Structures

Due to the growing demand for lightweight solutions in a wide range of industries, the selection and combination of various materials is becoming more and more important. As a result, the need for suitable joining technologies is increasing along with it. Within the DFG research group "Schwarz-Silber" ("black-silver"), Fraunhofer IFAM is investigating so-called transitional structures in cooperation with the University of Bremen. In this process, glass fiber structures are integrated into aluminum by a high pressure die casting process. These structures are used for the electrochemical insulation between aluminum and carbon fiber textiles, which are connected by textile processes in a subsequent production step. A solid hybrid structure is finally achieved through a resin-impregnation process. The key challenges are the positioning, pre-tensioning and infiltration of the glass fiber structures within the high pressure die casting process. In order to meet these challenges, a customized die casting tool was developed within the project. With the aid of mold-filling simulations, the die system of the die casting tool was optimized to achieve better infiltration of the fiber bundles and to additionally support the position of the glass fibers in the casting process. After the design of the molding tool, the implementation was carried out in collaboration with a toolmaker. In subsequent, up-to-date investigations, the positioning and infiltration of different variants of glass fiber structures is evaluated. The results are compared with previous attempts to position and infiltrate the glass fiber structures to assess the effect of the optimized newly designed tool.

Optimizing bioconversion of ferulic acid to vanillin by Bacillus subtilis in the stirred packed reactor using Box-Behnken design and desirability function.

A stirring bioreactor packed with a carbon fiber textiles (FT) biofilm formed by Bacillus subtilis was used to produce vanillin from ferulic acid. Biofilm formation was characterized by scanning electron microscopy. The interactive effects of three variables on vanillin molar yield (M) and conversion efficiency of ferulic acid (E) were evaluated by response surface methodology (RSM) with a Box-Behnken design (BBD). The optimal conversion conditions with a maximum overall desirability D of 0.983 were obtained by a desirability function. Considering the actual operation, the confirmation tests were performed using the slightly modified optimal conditions (initial ferulic acid concentration 1.55 g/L, temperature 35°C, stirring speed 220 rpm). The results showed that M and E were 57.42 and 93.53%, respectively. This was only 1.03% and 1.87%, respectively, different from the predicted values, confirming the validity of the predicted models. These revealed that the stirred packed reactor could be successfully used in vanillin bioconversion from ferulic acid.