Recycled Carbon Fiber Research Articles

Simulation of Flexible Recycled Carbon Fiber Wet Orientation and Its Composite Properties

Simulation of Flexible Recycled Carbon Fiber Wet Orientation and Its Composite Properties

Fujitsu, Teijin, V Frames and Advanced Bikes start trials to enhance environmental value of recycled carbon fiber in manufacturing bicycle frames

On January 19, 2023, Fujitsu Limited and Teijin Limited announced the launch of a joint project running from January to March 2023 to enhance the environmental value of recycled resources in the production of bicycle frames together with V Frames GmbH, a German manufacturer and distributor of carbon fiber reinforced plastic bicycle frames, and E Bike Advanced Technologies GmbH, a German manufacturer of bicycles.

Prediction of shear strength of CFRP-strengthened reinforced recycled aggregate concrete beams using various strengthening methods

Fibre reinforced polymer (FRP) strengthening is a possible option when the load carrying capacity of a structure needs to be increased for various reasons. On the other hand, the focus nowadays aims to save the environment by reducing the waste material. A suggestion was made to use waste concrete as an aggregate. If this new material was used more, it would be possible to use recycled concrete aggregate (RCA) and carbon fibre reinforced polymer (CFRP) to strengthen reinforced concrete (RC) structures and make them more environmentally friendly. An experimental investigation study on the shear behaviour of RC beams strengthened with CFRP strips was carried out. Tests were conducted on six reinforced concrete beams, with variations in the replacement ratio of RCA and strengthened by different configurations of CFRP under four-point loading. The results indicated that the load carrying capacity was increased, on average, by 18.09 and 35.04% for beams strengthened with CFRP with an inclined strip (IS) and continuous strip (CS) configurations respectively. The results also indicated that the increases in the stiffness were 21.08 and 37.31 for beams strengthened with CFRP in the IS and CS configurations, respectively. In addition the ductility of the beams increased after strengthening.

An Investigation of Mechanical Properties of Recycled Carbon Fiber Reinforced Ultra-High-Performance Concrete.

Carbon fiber-reinforced concrete as a structural material is attractive for civil infrastructure because of its light weight, high strength, and resistance to corrosion. Ultra-high performance concrete, possessing excellent mechanical properties, utilizes randomly oriented one-inch long steel fibers that are 200 microns in diameter, increasing the concrete's strength and durability, where steel fibers carry the tensile stress within the concrete similar to traditional rebar reinforcement and provide ductility. Virgin carbon fiber remains a market entry barrier for the high-volume production of fiber-reinforced concrete mix designs. In this research, the use of recycled carbon fiber to produce ultra-high-performance concrete is demonstrated for the first time. Recycled carbon fibers are a promising solution to mitigate costs and increase sustainability while retaining attractive mechanical properties as a reinforcement for concrete. A comprehensive study of process structure-properties relationships is conducted in this study for the use of recycled carbon fibers in ultra-high performance concrete. Factors such as pore formation and poor fiber distribution that can significantly affect its mechanical properties are evaluated. A mix design consisting of recycled carbon fiber and ultra-high-performance concrete was evaluated for mechanical properties and compared to an aerospace-grade and low-cost commercial carbon fiber with the same mix design. Additionally, the microstructure of concrete samples is evaluated non-destructively using high-resolution micro X-ray computed tomography to obtain 3D quantitative spatial pore size distribution information and fiber clumping. This study examines the compression, tension, and flexural properties of recycled carbon fibers reinforced concrete considering the microstructure of the concrete resulting from fiber dispersion.

Recycling Carbon Fiber from Carbon Fiber-Reinforced Polymer and Its Reuse in Photocatalysis: A Review.

Driven by various environmental and economic factors, it is emerging to adopt an efficient and sustainable strategy to recycle carbon fibers (rCFs) from carbon fiber-reinforced polymer (CFRP) wastes and reuse them in high-value applications. This review summarized the latest progress of CFRP waste recycling methods (including mechanical, chemical, and thermal methods), discussed their advantages and disadvantages, influence parameters and possible environmental effects, and their potential effects on the mechanical and surface chemical properties of rCFs. In addition, the latest optimization schemes of leading recycling technologies were detailed. According to the literature, CFs are the key points in the structural support of semiconductor-based recyclable photocatalytic systems and the enhancement of performance, which means that rCFs have high reuse potential in sustainable photocatalysis. Therefore, this paper also emphasized the possibility and potential value of reusing recovered fibers for developing recyclable photocatalytic products, which may be a new way of reuse in environmental purification often ignored by researchers and decision-makers in the field of CFs.

Mechanical response of recycled carbon fiber reinforced polymer fibers in high-strength concrete

The present paper studied the mechanical behavior of High Strength Concrete by incorporating recycled CFRP (Carbon Fiber Reinforced Polymer) fibers. The hardened properties of high-strength concrete were assessed using fiber volume fractions of 0.2 %, 0.4 %, 0.6 %, 0.8 %, and 1 % with a 30 mm average size of recycled chopped carbon fibers. The hardened properties of concrete test samples were evaluated using UPVT (Ultrasonic Pulse Velocity Test) and compressive strength test. Thirty-six specimens were tested at 28 days compressive strength to characterize mechanical properties. X-ray Diffraction analysis was carried out on a nominal mix test sample and a sample having an optimum dosage of fibers to characterize crystalline materials and understand the mineralogical properties of the concrete matrix. Analytical analysis was carried out using linear regression analysis for high-strength concrete's mechanical properties, considering different volume fractions or dosages of recycled chopped carbon fibers. The results showed that the increase in recycled chopped carbon fibers volume fractions or dosages enhances the compressive strength and increases the porosity of concrete samples up to the optimum dosage of recycled chopped carbon fibers.

High-Efficiency Carbon Fiber Recovery Method and Characterization of Carbon FIBER-Reinforced Epoxy/4,4'-Diaminodiphenyl Sulfone Composites.

Globally, the demand for carbon fiber-reinforced thermosetting plastics for various applications is increasing. As a result, the amount of waste from CFRPs is increasing every year, and the EU Council recommends recycling and reuse of CFRPs. Epoxy resin (EP) is used as a matrix for CFRPs, and amine hardeners are mainly used. However, no research has been conducted on recycling EP/4,4'-diaminodiphenyl sulfone (DDS)-based CFRP. In this study, the effect of steam and air pyrolysis conditions on the mechanical properties of re-cycled carbon fiber (r-CF) recovered from carbon fiber-reinforced thermosetting (epoxy/4,4'-diaminodiphenyl sulfone) plastics (CFRPs) was investigated. Steam pyrolysis enhanced resin degradation relative to N2. The tensile strength of the recovered r-CF was reduced by up to 35.12% due to oxidation by steam or air. However, the interfacial shear strength (IFSS) tended to increase by 9.18%, which is considered to be due to the increase in functional groups containing oxygen atoms and the roughness of the surface due to oxidation. The recycling of CFRP in both a steam and an air atmosphere caused a decrease in the tensile strength of r-CF. However, they were effective methods to recover r-CF that had a clean surface and increased IFSS.

The effect of carbon fiber content on physico-mechanical properties of recycled poly(ethylene terephthalate) composites additively manufactured with fused filament fabrication

The combination of recycled fiber reinforcement with recycled polymer as a feedstock material for extrusion-based additive manufacturing creates an opportunity for a more sustainable material use. In this study, recycled short carbon fibers were combined with recycled poly(ethylene terephthalate) (PET) to obtain carbon fiber-reinforced PET filaments via melt extrusion. The carbon fiber content of the extruded filaments ranged from 0.4 to 40.7 wt%. The molar mass and the degree of crystallinity after processing were determined to evaluate the influence of the extrusion process on the physico-chemical and mechanical properties of the reinforced PET filaments. Furthermore, pressure-volume-temperature measurements were carried out to investigate the influence of the carbon fibers on the shrinkage of the semi-crystalline PET. Samples were printed and their superior mechanical properties, including a 390 % increase in tensile modulus, were confirmed via tensile testing. Analysis via X-ray micro-computed tomography indicated that the fiber length reduced with increasing fiber content. The high degree of fiber alignment that was observed in the extruded filaments, was slightly reduced after deposition. Scanning electron microscopy data showed that fiber pull-out was the governing failure mechanism, indicating a weak interface between the carbon fibers and the matrix. The results show the potential of extrusion-based additive manufacturing to valorize recycled PET and recycled carbon fibers. • Extrusion of recycled carbon fiber/recycled poly(ethylene terephthalate) filaments • Characterization of filaments with carbon fiber content ranging from 0.4 to 40.7 wt% • Study of the influence of the extrusion process on the molar mass • Reduced shrinkage and increased tensile modulus of reinforced printed parts • Characterization of fiber length and orientation in filaments and printed parts

Modification of Glass/Epoxy laminates using micro/nano particles from carbon wastes

This study is focused on the influence of a modified matrix on glass fiber reinforced laminates, which inherently have different material properties than carbon fiber composites. For this study we modified the green epoxy resin with 2.5wt% of carbon based fillers (synthesized graphene nanopellets, and milled recycled carbon fibres), which were subsequently applied to the glass multifilaments, and vacuum cured to obtain fiber/epoxy UD laminates. The prepared samples were further tested on the mechanical, thermo-mechanical and electrical properties, to evaluate the filler influence on the studied type of glass/epoxy laminates. Aim of this work is to study the influence of carbon fillers on overall composite properties, and evaluate its applicability for the improvement of UD glass epoxy laminates without having to significantly change the weight of component and the technology of the composite production.

Recycling of carbon fiber reinforced polymers in a subcritical acetic acid solution

A novel single-stage solvolysis process is demonstrated for recycling carbon fibers from an epoxy-based composite material using 50 wt% acetic acid solution under subcritical conditions. The process yields 100% fiber recovery efficiency in less than 30 min at 300 °C. Qualitative SEM/EDS analysis of the fibers reveals that the recovered fibers are entirely free of resin, and the carbon fiber surfaces were not damaged. SEM images and gravimetric measurements of the composites treated at lower temperatures and short residence times show an initial increase in mass of the CFRP samples, suggesting a two-step process consisting of initial composite swelling due to uptake of solvent, followed by depolymerization and chemical decomposition of the polymer. FTIR and GC-MS analyses confirm resin decomposition and production of aromatic and aliphatic compounds.

Lightweight, flexible, and highly conductive recycled carbon fiber felt for electromagnetic interference shielding

With the explosive growth of electrocommunication and portable electronics, exploiting the superior electromagnetic interference (EMI) shielding materials with the desired flexibility and lightweight is critical. Herein, the waste carbon fibers (CFs) eco-friendly recycling strategy and a facile and cost-effective paper-making method are utilized to prepare recycled carbon fiber felt (rCFF) decorated with cationic polyacrylamide (CPAM) (rCFF/CPAM). Profiting from the inherent excellent conductivity of lossless recycled carbon fibers (rCFs) and optimum rCFs dispersion in CPAM, the abundant efficient pathways are constructed in the 3D interconnected rCFF/CPAM networks, resulting in the rCFF/CPAM exhibits a remarkable electrical conductivity of 140.06 S/m, a highly efficient EMI shielding effectiveness (EMI SE) of 66.15 dB and an exceptional of SEA/SET ratio of 83.8 % at 0.875 mm. More importantly, the felt also contains the advantages of outstanding flexibility, lightweight and sustainable re-utilization. In summary, this strategy provides an economical and practical way to manufacture the superior performance rCFF/CAPM, but also promotes the high value recycle and reuse of waste carbon fiber resources.

A bio-based intrinsically flame-retardant epoxy vitrimer from furan derivatives and its application in recyclable carbon fiber composites

The recycling of carbon fiber reinforced polymer composites (CFRPCs) is difficult because the thermosetting matrix is insoluble and does not melt. To overcome this problem, a furan-derived epoxy resin (HMF-GAN-EP) was synthesized from 5-hydroxymethylfurfural and cured with a furan-based curing agent (DIFFA). The cured HMF-GAN-EP/DIFFA system showed excellent flame retardancy (UL-94 V-0 and LOI of 40%). The glass transition temperature, tensile strength, and tensile modulus of the cured HMF-GAN-EP/DIFFA system were approximately 234 °C, 67 MPa and 2273 MPa, respectively, all of which were higher than those of the diglycidyl ether of bisphenol A (DGEBA)-type epoxy thermosets cured by 4,4′-diaminodiphenylmethane (DDM) (151 °C, 56 MPa and 1744 MPa). The cured HMF-GAN-EP/DIFFA system could dissolve in a mixed solution of THF:HCl (8:2, v/v), making it possible for the recycling of carbon fibers from CFRPCs.

Hybrid Polyethylene Composites with Recycled Carbon Fibres and Hemp Fibres Produced by Rotational Moulding

This study assessed polyethene composites produced by rotational moulding with hybrid reinforcement using recycled carbon fibre (RCF) and hemp fibre (HF). First, the RCF was treated with nitric acid to introduce hydroxyl groups on the fibres’ surface and was characterised by infrared spectroscopy and microscopy analyses. Although the fibre surface treatment improved the tensile properties of the composites, the use of grafted maleic anhydride polyethylene (MAPE) as a coupling agent was more effective in improving the interfacial bonding between the fibres and the matrix. Alkali-treated hemp fibres were then used in combination with RCF to produce rotationally moulded composites with an overall fibre content of 10 wt.% but with different ratios of HF/RCF, namely, (20/80) and (50/50). The results showed that the addition of RCF increased the composite’s Young’s modulus compared to neat PE, regardless of the fibre treatment. Similarly, the hybrid composites showed superior Young’s moduli than the HF–PE composites through the increase in the RCF content. It was also observed that adding RCF reduced the void size within the final composites compared to the HF–PE composites, which contributed to the greater performance of the hybrid composites compared to their natural counterparts.

Investigating the influence of plasma treated polyethylene powder, carbon fibers in enhancing the mechanical properties of polymer composites using rotomoulding method

AbstractIn this research, rotomoulded samples of polyethylene (PE) were mechanically tested to find better applications. The mold was kept in an oven at 260°C with forced convection. Total fabrication time depended on peak internal air temperature (PIAT) used with 200, 220 and 240°C to confirm the fabrication conditions. The plasma treatment of PE and recycled carbon fiber (CF) was used for the improvement of properties. Maximum tensile strength (TS) of 23.1 MPa was observed in 10 wt% CF/PE composites. Scanning electron microscope (SEM) results revealed good mechanical interlocking with higher chemical interaction of carbon fiber of up to 10 wt% with plasma polyethylene leading to good mechanical properties in the composites. Flexural strength (FS) of 19.98–26.02 MPa in the properties was observed plasma treated in the PE with CF (3–10 wt%) combination. Agglomeration in the carbon fiber lowered flexural properties of 13, 15 wt% filler with both plasma and non‐plasma PE. The CF (3–10 wt%) with plasma PE showed enhanced impact strength (IS) from 6.84 to 8.64 KJ/m2. Maximum TS, FS and IS were observed with peak internal air temperature (PIAT) of 200°C. Surface images showed even distribution of fiber and resin in the plasma treated matrix in 5 wt% CF combinations. The differential scanning calorimetry (DSC) results do not show fluctuations in the melting and crystallization temperatures of the samples after plasma treatment.

Characterization of Composites Manufactured Through Reshaping of EoL Thermoplastic Polymers Reinforced with Recycled Carbon Fibers

This article investigates if and at what extent a recycling process based on grinding, melting and re-shaping of recycled carbon fibers reinforced thermoplastic polymers (rCFRPs) can affect their physical, mechanical and thermal properties. The aim is to establish if they can be taken into consideration in the manufacturing of new composite materials in different sectors: automotive, marine, sporting goods, etc. Composites materials were submitted to the measurement of the fibers length they are composed of, and then analyzed by means of tensile and impact tests and a dynamic mechanical analysis (DMA). All the characterizations were performed to both initial and recycled composites and, in some cases, they were replied also after the intermediate accelerated aging. Characterization performed confirmed that, as expected, the recycling process affects the properties of the composites, but in different manners and to a different extent when different polymers are involved. Tensile and impact tests pointed out that the polypropylene based composites showed a less stiff and a more brittle behaviour after the recycling process and the DMA confirmed this evidence, highlighting in addition a more viscous behavior of the polymer after the recycling. Conversely, the polyamide 6 based composites increased their stiffness and ductility after the recycling. For all the composites the tensile strength dropped, confirming the weakening of the materials.

TENSILE TEST OF CARBON CLOTH COMPOSITE WITH MATRIX POLYPROYLENE RECYCLING WITH WORKING TEMPERATURE PARAMETER OF 600℃ WITH METAL AND CERAMIC PRESS MEDIA

Right now the distribution of polypropylene in the environment has become more and more so that it can pollute the environment. Thus polypropylene waste can be converted into a composite matrix. In this study, the manufacture of composites from recycled polypropylene was carried out, to be further combined with carbon fiber. After that, tensile testing is carried out to find out the mechanical properties. As a variation, there are differences in press media, namely using metal and ceramics. This research method is carried out experimentally, where when polypropylene waste has been softened using a heat gun at a temperature of 600 °C, it is emphasized using aluminum metal and ceramics so that polypropylene can be solid. Then for the dimensions of its manufacture according to ASTM D 638 for recycled polypropylene and ASTM D3039 for recycled polypropylene matrix carbon fiber composites. From the tensile test results for ASTM D638, specimens with suppression treatment using metal press media have an average maximum tensile strength of 5.40 MPa. As for specimens with ceramic press media has an average value of 6.32 MPa. Tensile testing on recycled polypropylene matrix carbon fiber composite specimens showed tensile strength with a value of 7.53 MPa for the treatment of metal press media and for ceramic press media its strength value of 10.66 MPa. Thus ceramic press media in the polypropylene composite manufacturing process is better than metal press media

Mechanically robust, hydrothermal aging resistant, imine-containing epoxy thermoset for recyclable carbon fiber reinforced composites

Imine compounds have been proved to possess great potential in the design and preparation of sustainable epoxy thermosets. However, it is still a great challenge to develop imine-containing hardener with definite structure due to the randomness of condensation reaction between aldehydes and primary amines. Herein, a novel amine hardener containing imine bond is synthesized successfully by selecting 4-imidazole formaldehyde and 3-aminobenzylamine as raw materials. The asymmetric structure of raw material can avoid uncontrollable reaction and ensure that this hardener possesses definite chemical structure. Due to high activity of hardener, the resultant epoxy thermosets with high cross-linked density exhibit excellent thermostability and fine hydrothermal aging resistance. Furthermore, such thermosets show good mechanical properties (tensile strength of ∼76 MPa), which are comparable to that of commercial Diglycidyl Ether of Bisphenol A epoxy resin cured by 4,4-Diaminodiphenyl methane. More interestingly, increasing the equivalent ratio of active hydrogen to epoxy can introduce more dynamic covalent C=N linkage into the cross-linked network, thus the epoxy thermoset further achieves the decomposition within 3 h and the corresponding composite laminates also are recycled efficiently under mild condition. This work demonstrates the feasibility and potential of preparing high-performance degradable epoxy thermoset and corresponding recyclable composites based on well-designed imine-containing hardener.

Upcycling of carbon fiber-reinforced polymer composites

An upcycling method of carbon fiber-reinforced polymer (CFRP) was proposed to solve environmental pollution caused by waste CFRP. Novel graphene supported on alumina fiber porous material (GPM) was prepared, which could generate plasma under microwave irradiation in a nitrogen atmosphere. This plasma could generate a high temperature that not only pyrolyzed the thermosetting polymer in CFRP into combustible gas but also improved the graphitization degree of recycled carbon fiber (CF) beyond that of the virgin CF. This upcycling method obtained T300 short-cut carbon fiber (SCF) without additional surface treatment has better properties than commercial T700 SCF when prepared composite.

Recovery of carbon fiber-reinforced polymer waste using dimethylacetamide base on the resin swelling principle.

The mechanical recycling method of the carbon fiber-reinforced polymer (CFRP) has the advantages of simple process, less pollution and low cost, but only low utilization value of carbon fibers in powder or short fibers form can be obtained. To reduce the length and strength loss of the recycled carbon fibers, a novel and cost-effective dimethylacetamide (DMAC) swelling technique was developed to achieve rapid delamination of the CFRP laminates under mild conditions (120°C-160°C, 1h). The corresponding swelling ratios and mass-loss rates of cured epoxy resin (CEP) were about 121.39%-157.39% and 0-0.69%, respectively. Excessive swelling of CEP in DMAC resulted in the cracking of the resin matrix between the adjacent carbon fiber layers. Thus the CFRP laminates were delaminated into soft single carbon fiber layers, which showed excellent cutting performance and reinforcing properties. The delamination products were cut into thin strips of different sizes and vacuum bag molded into new CFRP laminates. The flexural strength and tensile strength of the newly produced CFRP laminates were about 76.38%-90.98% and 94.61%-98.54% of the original CFRP laminates, respectively. More importantly, the chemical compositions of DMAC and CEP were unchanged during the physical swelling process. No organic pollutants (caused by resin degradation) were generated. And the used DMAC can be easily recycled by filtration. Therefore, this study provides a strategy for low-cost and high-valued recycling of CFRP waste.

Recycled carbon fibers as an alternative reinforcement in UHMWPE composite. Circular economy within polymer tribology

The increasing demand of carbon fiber reinforced polymers over the last few decades has brought attention to critical aspects such as disposal, environmental impact, and cost of production. Therefore, adopting a circular economy approach focused on improving efficiency is an enticing alternative nowadays. This investigation is focused on the mechanical and tribological characterization of ultra high molecular weight polyethylene (UHMWPE) composites reinforced with virgin (vCF) and recycled carbon fibers (rCF) under water lubricated conditions. An improvement of 208% in Young’s modulus, 105% in ultimate tensile strength and 146% in hardness for the samples with 30%wt rCF, compared to pure UHMWPE, was observed. Reductions of up to 62% in coefficient of friction and 32% in wear rates for 10 wt% CF composites were obtained, facilitated through the formation of a transfer film, which was present on the countersurfaces. The results of this project show that the composites containing recycled fibers exhibit a comparable performance to their virgin counterparts. An economical evaluation estimated possible monetary savings of 910.2 M€ in a time span from 2022 to 2026 by using rCF in composite production, providing arguments for the use of rCF reducing the environmental impact and cost without compromising performance.