Virgin Carbon Fibers Research Articles

A comprehensive review of surface modification techniques for carbon fibers for enhanced performance of resulting composites

Carbon fiber (CF) is being used as reinforcements in structural composites due to its high strength-to-weight ratio, chemical and abrasion resistance. However, due to the inert surface of the fiber, the resulting CFRPs provide limited damage resistance. The CFRPs are prone to delamination and offer poor interfacial strength. Secondly, recycled carbon fiber (RCF) cannot be used for strength applications in electric vehicles and aerospace applications due to the limited strength offered by the CFRPs made from RCFs. So, in order to use recycled and virgin CF in the field of electric vehicles and aerospace, the modification to the surface of the CF is required for enhanced interfacial properties in the resulting composite. This is a comprehensive review on surface modification techniques used to induce physical and chemical changes on the CF surface. The modified surface of CF can lead to enhanced performance of the structural composites. The review article discusses the various surface modification techniques categorized as plasma, chemical, nano-particle growth, coating, and microwave irradiation in detail, with suitable illustrations that have been used to ameliorate the compatibility of the CF with the matrix.

Improving recycled carbon fiber by single walled carbon nanotubes in reinforcement of polyamide composites

Recycled carbon fibers (rCF) represent an inexpensive alternative to virgin carbon fibers (CF) but the mechanical improvement brought by rCF to polymer composites is noticeably lower than that from CF. In this article we evaluate two methods of coating rCF by single walled carbon nanotubes (SWCNTs), wet and dry, and demonstrate that extremely low concentrations of SWCNTs, ∼0.03%, are sufficient to measurably improve the strength (by 16%), modulus (by 38%), and Izod impact strength (by 52%) of thermoplastic crystalline polyamide polyxylylene adipamide (MXD6) with 30% rCF. The dry method with grinding of rCF and SWCNTs works better than the wet (dip coating) method and the rCF with residual epoxy is better than purified by pyrolysis rCF. We link this improvement of the mechanical properties to the enhanced crystallization rate caused by SWCNTs, which is observed in differential scanning calorimetry (DSC).

Tailorable mechanical and energy absorption behaviors of 3D printed continuous hybrid fiber reinforced composites

Abstract3D printing of continuous fiber‐reinforced thermoplastic composites (CFRPCs) has expanded potential structural application in recent years. However, it is still challenging to tailor the mechanical and energy absorption properties of 3D‐printed composites to fulfill the requirements for critical application conditions. Herein, hybrid fiber (HF) reinforced composites have been prepared by 3D printing of CFRPCs and investigated on the mechanical and energy absorption behaviors. Continuous virgin carbon fibers (CF), Kevlar fibers (KF) (130 Deniers (D), and 200 Deniers (D)) and E‐glass fibers (GF) were used as reinforcing fibers to produce hybrid and non‐hybrids composites. Hybrid composites with different combination of CF + GF, CF + 130D KF, and CF + 200D KF showed tailorable behaviors, such as flexural modulus (16,691.74, 20,372.38, and 19,017.44 MPa), tensile modulus (15,022.6, 16,269.41, and 15,320.58 MPa). And energy absorption behaviors of CF + 130D KF and CF + 200D KF were tailored in both tensile (18,865.25 and 20,302.07 N‐mm, respectively) and bending (3594.54 and 3570.80 N‐mm, respectively) tests compared to other composites which will be ideal for energy absorption applications. Moreover, CF + GF showed tailored strength which could be used in the need of high stiffness. SEM images were providing strong evidence to resist the fracture and breakage patterns, by tailoring the stiffness and elongation properties of fibers in hybrids specimens. Furthermore, positive hybrid effects of CF + KF hybrids in tensile and bending tests were also showing an ideal match of toughness and flexibility. In future, these cost and weight effective hybrids will have potential to apply in aerospace and automobile.

Life cycle assessment of carbon ceramic matrix composite brake discs containing reclaimed prepreg scraps

In the last years, carbon ceramic brakes are preferred to traditional cast iron ones for their lightweight, high temperature resistance, and long service life, even though their manufacturing involves the use of high temperature processes and energy-intensive materials such as carbon fibers. Within the European Life Project “CIRCE”, a novel recovery system for carbon fiber prepreg scraps was developed to reclaim high-quality carbon fibers to use as a substitute of virgin carbon fibers in different application, such as in Ceramic Matrix Composite (CMC) brakes. In order to overcome the lack of scientific literature regarding the environmental sustainability of steel and CMC brakes, in the present paper, the Life Cycle Assessment (LCA) methodology was applied to carry out a detailed analysis of the environmental impacts associated with carbon ceramic brakes realized using the reclaimed prepreg scraps. The functional unit was defined as production, use and disposal of a rear brake disc used for the deceleration of a sport car during its lifetime. Different impact indicators were considered, such as Global Warming Potential, Cumulative Energy Deman and ReCiPe midpoint categories. The results were compared to those given by the sustainability assessment of cast iron disc brakes and traditional carbon ceramic brakes. The proposed LCA is a cradle to grave analysis, as it considers all the relevant inputs and outputs of the manufacturing processes, from the raw material extraction to the materials disposal. The surface of ceramic brakes was observed using Scanning Electron Microscopy to assess the different material structures. The results show that, as far as the production is concerned, cast iron brakes are the most sustainable alternative, with impacts lower than 21% of the composite component ones. However, if a long use phase more than 200,000 km is evaluated, carbon ceramic brakes obtained by reclaimed prepreg scraps are characterized by lower environmental impacts, with impacts that are about 8% lower than those obtained by traditional carbon ceramic brakes.

Preparation and properties of carbon fiber reinforced bio‐based degradable acetal‐linkage‐containing epoxy resin composites by RTM process

AbstractThe recycling of carbon fiber (CF) reinforced bio‐based degradable epoxy resin composites is of great significance for resource saving, environment protection and sustainable development of economy and society. Resin transfer molding (RTM) has been recognized as one of the most promising processes to manufacture CF Reinforced polymeric composites cost‐effectively. The bio‐based diglycidyl ether pentaerythritol vanillin diacetal (DEPVD) epoxy resin used in this study is an epoxy resin that can be degradable under mild conditions. And its CF composites were prepared by the RTM process using DDS as a curing agent and low viscosity bisphenol A‐E51 epoxy resin as a diluent. The chemical rheological properties, curing behavior, thermal stability, dynamic viscoelasticity and mechanical properties of DDS‐E51‐DDS epoxy resin were investigated. It is found that the increase of DEPVD content is beneficial to improve the mechanical properties, Tg and solid residue after thermal degradation of DEPVD‐E51‐DDS epoxy resin. Moreover, the effects of DEPVD content in epoxy resin on the mechanical properties of CF/DEPVD‐E51‐DDS composites were evaluated. When the DEPVD content is 70%, the tensile and flexural strength of CF/EPVD‐E51‐DDS composites are 1649.4 MPa and 1207.4 MPa, respectively. The degradability and mechanism of CF/DEPVD‐E51‐DDS composites were further investigated. CF/DEPVD‐E51‐DDS composites containing 70% DEPVD have excellent degradability, and the recycled CFs exhibit comparable mechanical properties to the virgin CFs, which demonstrates a novel way to recover the high‐quality of used CFs.

Enhanced electrodynamic properties acrylonitrile butadiene styrene composites containing short-chopped recycled carbon fibers and magnetite

The development of new polymer composites with conductive and magnetic fillers that are compatible with additive manufacturing (AM) is a highly topical issue. In this work, we discussed the effect of short virgin/reclaimed carbon fibers and magnetite on the electrodynamic properties of acrylonitrile butadiene styrene (ABS) in the X-band frequencies. The choice of selected frequency range is connected with a large number of various radio engineering systems operating with these frequencies, including radar and satellite communication systems. Composites with the addition of short carbon fiber and magnetite exhibit excellent shielding factors ranging from 37.9 to 33.7 dB at frequencies 8–12 GHz. A detailed study of the electrodynamic parameters revealed the attractive properties of reclaimed carbon fiber as a component of shielding materials, especially with the simultaneous addition of magnetite. It should be noted that for this particular composite, the permittivity imaginary part increase was up to −23.96 (88 %) at 8 GHz compared to the virgin carbon fiber and magnetite composite.

Recovery of carbon fibers from carbon fiber-reinforced epoxy-isophorone diamine composites via step thermolysis

Thermosetting composites are widely used in various industries owing to their excellent mechanical properties, dimensional stability, and convenient formability. However, once cured with epoxy resin, the separation of thermosetting composites from carbon fibers is challenging. Industrial waste resulting from end-of-service-life carbon fiber-reinforced thermosetting plastic (CFRP) is a significant environmental problem. Thus, eco-friendly and economic processes must be developed to increase resource efficiency by converting waste CFRP into reusable materials. This study aims to find the optimal conditions for the recovery of recycled carbon fiber (r-CF) from thermoset CFRP manufactured using epoxy (EP) and isophorone diamine (IPDA). A multi-step thermolysis method using superheated steam and air was proposed. We confirmed that an oxidizing atmosphere is required to recover clean r-CF without char. The mechanical strength of the recovered r-CF was dependent on the pyrolysis temperature and time, which was due to an increase in defects from the oxidative decomposition of the r-CF surface. Finally, the recovery rate was 95%, and the tensile strength of the recycled carbon fiber was 80% higher than that of virgin carbon fiber.

Recycled Carbon Fibers with Improved Physical Properties Recovered from CFRP by Nitric Acid

To effectively reuse a large amount of Carbon Fiber Reinforced Plastics (CFRP) waste, the carbon fibers should be able to be recovered without degrading their quality. In this report, we developed a new approach to recover carbon fibers from CFRPs with improved physical properties compared to virgin carbon fibers with an environmentally friendly recycling method using nitric acid. Following the decomposition of the CFRP waste in nitric acid at 80 °C, both recycled carbon fibers and decomposed resin were recovered. The obtained recycled carbon fibers showed 1.4 times higher tensile strength and 2.2 times higher interfacial shear strength to resin compared to virgin carbon fibers. TEM-EDX analysis showed a decrease in the abundance of voids existing in the carbon fiber surface layer and new polar functional groups caused by nitric acid existing inside the voids, leading to increased tensile strength. Furthermore, XPS analysis showed that the interfacial shear strength improved due to the formation of new polar functional groups due to nitric acid. The possibility of applying recycled carbon fibers to CFRP products was shown by elucidating the mechanism that expressed its physical properties during the recycling process, leading to a novel approach to realizing closed-loop recycling.

Recycled Carbon Fibre Composites in Automotive Manufacturing

Article Recycled Carbon Fibre Composites in Automotive Manufacturing Jean-Baptiste R. G. Souppez 1, * , and Geethanjali S. Pavar 2 1 Department of Mechanical, Biomedical and Design Engineering, School of Engineering and Technology, College of Engineering and Physical Sciences, Aston University, Birmingham B4 7ET, UK. 2 Institute for Energy Systems, School of Engineering, University of Edinburgh, Edinburgh EH9 3JW, UK. * Correspondence: j.souppez@aston.ac.uk Received: 9 January 2023 Accepted: 22 February 2023 Published: 6 March 2023 Abstract: The contemporary need for lightweight and sustainable materials in automotive manufacturing has made recycled carbon fibre an attractive option. Yet, aspects such as the mechanical properties of short fibre composites need to be characterised to fully identify the capabilities and opportunities for recycled carbon fibre in the automotive industry. Consequently, this paper aims to ascertain the potential of recycled carbon fibre materials for automotive manufacturing by considering mechanical properties, design implications, and resulting costs and sustainability. Destructive testing is employed to characterise the mechanical properties of virgin carbon fibre (VCF), recycled carbon fibre (RCF) using pyrolysis, and blended recycled carbon fibre (BRCF) comprising 50% polypropylene fibre. Here we quantify (i) the reduction in mechanical properties, namely the tensile modulus and breaking strength, (ii) the resulting increase in required thickness and therefore mass for manufactured parts and (iii) the reduction in cost and embodied energy achieved for RCF and BRCF compared to VCF, based on both a stiffness- and a strength-driven design criterion. Furthermore, we present a decision-making methodology revealing BRCF as the most cost-effective solution, while RCF proves to be the most sustainable alternative. These results provide a novel quantitative assessment of recycled carbon fibre for automotive manufacturing and may contribute to future developments in sustainable composite manufacturing in the automotive industry.

Dispersibility optimization of short carbon fiber suspension for the preparation of carbon fiber aligned mat reinforced composites

There is significant interest in the reuse of reclaimed carbon fiber (rCF) due to its economic potential and the minimization of environmental impact. However, the sub-optimal state of short rCF adversely affects its reuse value. In this paper, short rCF was aligned using wet alignment technology and the dispersibility of short carbon fiber (SCF) suspension was investigated, along with virgin carbon fiber (vCF) and rCF aligned mat reinforced epoxy (EP). The results show that the main factors that affect the dispersion rate (γ) are the HEC content, CF length, CF content and ultrasonic power, in diminishing order of magnitude of impact. The HEC content was positively correlated with γ, and the CF length and CF content negatively correlated with γ. When the ultrasonic power was less than 50%, it was positively correlated with γ, and higher than 50%, it was negatively correlated. This work suggests that the dispersibility optimization of SCF suspension to obtain well aligned rCF mat offers a possible strategy to obtain an improved quality form of rCF.

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.

Recovery of carbon fibers from aviation epoxy composites by acid solvolysis

Aircraft industries produce massive quantities of carbon fiber reinforced polymers which must be recycled to comply with the directives of the circular economy. In this context, carbon fiber of reinforced epoxy resin composites from the aircraft construction industry were recovered by nitric acid-catalyzed hydrolysis at 95 °C. The operating conditions, such as the concentration of nitric acid, the weight ratio composite/solution, and the number of cycles of the ultraviolet treatment (UVB) irradiation were studied. UVB was used to induce the polymer degradation and thus decrease the severity of the hydrolysis process. The UVB treatments were performed in a weathering chamber at 60 °C. The reclaimed carbon fibers and virgin carbon fibers, used as standard, were characterized by X-ray diffraction, Raman spectroscopy, thermogravimetry under airflow, and scanning electron microscopy (SEM). As expected, UVB irradiation was able to initiate the polymer degradation process which was beneficial for the overall recycling process. Data from characterization techniques showed that the UVB irradiation caused some damage to carbon fibers. Without irradiation pre-treatment, the collected fibers showed characteristics like those of virgin fibers with a slight decrease in thermal stability which can arise from surface oxidation. The tensile strength of recovered fibers was sensitive to nitric acid concentration during hydrolysis because long contact time with acidic solutions causes oxidation of CF. Optimization of nitric acid concentration and hydrolysis step duration must be carried out to minimize CF surface oxidation.

Cradle-to-Gate life cycle assessment of recycling processes for carbon fibers: A case study of ex-ante life cycle assessment for commercially feasible pyrolysis and solvolysis approaches

Waste that derives from manufacturing processes and end-of-life products of the transportation industry is a cause of increasing concern globally. Therefore, systems must be developed to manage such waste and to mitigate greenhouse gas (GHG) emissions. In this study, the carbon fiber reinforced polymer (CFRP) recycle process was analyzed to assess its environmental friendliness. The recycling processes at the Carbon Fiber Recycling Co., i.e., pyrolysis, and Hitachi Chemical, i.e., solvolysis, both of which are currently in production scale, were analyzed. The scaling effect was employed to assess the environmental impacts of the production scale. The results showed that either recycling method offers promising results for reducing environmental impacts, as compared with producing virgin carbon fibers (vCFs). GHG emissions from the Carbon Fiber Recycling Co. pyrolysis were 1.52 kg-CO2 eq/kg while that of Hitachi Chemical solvolysis was 1.92 kg-CO2 eq/kg. GHG emissions resulting from both methods were below the GHG emissions produced by vCFs (24.00 kg-CO2eq/kg). By factoring the GHG credits created from the by-products of these processes, the GHG emissions from the Carbon Fiber Recycling Co. pyrolysis were 0.57 kg-CO2 eq/kg and that from Hitachi Chemical solvolysis was −0.54 kg-CO2 eq/kg. Additionally, the results of this study were consistent with other GHG studies, suggesting credibility.

A closed-loop recycling process for carbon fiber-reinforced polymer waste using thermally activated oxide semiconductors: Carbon fiber recycling, characterization and life cycle assessment

The objective of this study is to investigate the properties of recycled carbon fiber (rCF) and its environmental impact, with a specific focus on the energy consumption of the recycling process based on the use of thermally activated oxide semiconductors (TASC). The mechanical and surface properties of rCF obtained under the optimal process parameters were characterized. The life cycle assessment method was used to evaluate the environmental impact of a closed-loop recycling process for carbon fiber-reinforced polymer (CFRP) waste using TASC. The results indicated that the decomposition rate of resin was 95.5 %, and no carbonaceous solid was generated. The gaseous produced of the recycling process were mainly CO2 and H2O, and no liquid products were produced. The surface oxidation degree of rCF was relatively slight. COOH was generated on the surface of rCF, which was conducive to improving the interfacial adhesion viscosity with resin. The monofilament tensile strength of rCF was maintained above 97 %. Compared with landfill and incineration, CFRP waste recycling using TASC can make global warming potential, acidification potential and eutrophication potential reduced by 28 %, 32 %, and 25 %, respectively. Ozone layer depletion potential, human toxicity potential and terrestrial ecotoxicity potential in disposing CFRP waste using TASC were 30 %, 21 % and 41 % of that using pyrolysis, respectively. The energy consumption in carbon fiber recycling by TASC was only 23 % of that in virgin carbon fiber manufacturing. TASC is found to be a promising potential strategy for managing CFRP waste.

Auto-catalytic high-performance recyclable carbon fiber reinforced epoxy composites mediated by neighboring group participation

Epoxy-based carbon fiber reinforced composites (CFRCs) are leading contenders in high-tech fields. However, the majority of CFRCs consisted of thermoset matrix and carbon fibers (CFs) are costly to produce and difficult to recycle. In this study, this problem has been solved by a simple strategy to prepare high-performance recyclable CFRCs from commercial-scale low-cost phthalic anhydride (PA) and diglycidyl ester of aliphatic cyclo (DGEAC). The rigid DGEAC/PA networks resulted in a glass transition temperature of ∼214 °C, a tensile strength of ∼79 MPa, and a Young’s modulus of ∼1.84 GPa. More importantly, the neighboring group participation (NGP) effect facilitated the transesterification reactions (TERs), making DGEAC/PA networks degradable in ethylene glycol. Accordingly, the CF/DGEAC/PA composites exhibited good mechanical properties comparable to conventional epoxy CFRCs, and the CFs could be recycled completely with similar features of the virgin CFs. This work provides an auto-catalytic sustainable approach for high-performance degradable CFRCs.

A Review on Recycling of Carbon Fibres: Methods to Reinforce and Expected Fibre Composite Degradations.

Carbon fibres are widely used in modern industrial applications as they are high-strength, light in weight and more reliable than other materials. The increase in the usage of carbon fibres has led to the production of a significant amount of waste. This has become a global issue because valuable carbon fibre waste ends up in landfill. A few initiatives have been undertaken by several researchers to recycle carbon fibre waste; however, the properties of this recycled material are expected to be worse than those of virgin carbon fibre. The incorporation of polymers, nanoparticles and other hybrid materials could enhance the overall properties of recycled carbon fibre waste. However, the degradation of fibre composites is expected to occur when the material is exposed to certain conditions and environments. The study of fibre composite degradation is crucial to enhance their properties, strength, safety and durability for future applications.

Towards sustainability in 3D printing of thermoplastic composites: Evaluation of recycled carbon fibers as reinforcing agent for FDM filament production and 3D printing

The use of recycled Carbon Fibers (rCFs) into polylactic acid (PLA) matrix to produce new reinforced 3D printing filaments was assessed. Filaments containing 5 and 10 wt% of rCFs were manufactured and, in order to compare the effect of the partial oxidized surface of recycled CFs on the adhesion with PLA matrix, filaments of pure PLA and with the same concentration of washed virgin Carbon Fibers (vCFs) were also produced. As expected the addition of CFs impacts the 3D printed thermal and mechanical properties, leading to the reduction of thermal expansion up to 85% and to a substantial increase of the storage modulus up to 7.1 GPa for PLA/vCF10. Furthermore this study underlines that the use of rCFs leads to a thermo-mechanical performance well comparable with that of the analogue virgin fibers based materials, supporting the suitability of recycled CFs for 3D printing applications. Indeed, when the fiber aspect ratio is not a crucial detrimental point, the quality of recycled CFs has now achieved performances that make them a better alternative to the pristine fibers, in particular when economic aspects are also taken into account.

Evaluation of Mechanical Properties and Pyrolysis Products of Carbon Fibers Recycled by Microwave Pyrolysis

Disposal of the waste from carbon fiber reinforced polymers (CFRPs) has become an urgent problem due to the increasing application of CFRPs in many industries. A novel method for the rapid recovery of carbon fibers by a microwave pyrolysis and oxidation process was proposed in this study. The resin matrix was rapidly pyrolyzed by heating CFRPs directly with microwave radiation, and then the residual carbon and organic matter on the surface of carbon fibers were removed by oxidation to obtain recycled carbon fibers (RCFs). The recovery rate of recycled carbon fibers was measured, and their mechanical properties were evaluated by tensile strength and tensile modulus tests. The results showed that, after microwave pyrolysis at 500 °C for 15 min and oxidation at 550 °C for 30 min, the maximum tensile strength of RCFs was 3042.90 MPa (about 99.42% of that of virgin carbon fibers), the tensile modulus was 239.39 GPa, and the recovery rate was about 96.5%. The microstructure and chemical composition of RCFs were characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy, and the components of the pyrolysis byproducts were detected by gas chromatography–mass spectrometry. These results indicate that this method is suitable for the effective recovery of high-quality carbon fibers from CFRPs.

Research on a two-step pyrolysis-oxidation process of carbon fiber-reinforced epoxy resin-based composites and analysis of product properties

The recycling of carbon fiber is the focus of current research as carbon fiber-reinforced polymer (CFRP) waste have increased. Pyrolysis has been identified as an effective method for recycling CFRP. In this study, the surface resin of CFRP was first pyrolyzed, and then the residual carbon on the surface of the pyrolysis product was oxidized to recover carbon fiber. This work focused on the effect of various oxidation conditions on the recovery rate, mechanical properties, and electrical conductivity of RCFs. The results show that the carbon fibers recovered via pyrolysis at 600 ℃ for 30 min and oxidation at 450 ℃ for 15–20 min have better mechanical properties. The tensile strength can exceed 90.19% of the virgin carbon fiber (VCF), the tensile modulus can exceed 84.44% of the VCF, the electrical conductivity can exceed 70% of the VCF, and the recovery rate will exceed 95.22%. Furthermore, the results of simulating the high-temperature pyrolysis environment of CFRP showed that the high-temperature pyrolysis products mainly contained oxygenated aromatic compounds such as 3-Methyltetrahydrophthalic anhydride and Bisphenol-A.

Controlling degradation and recycling of carbon fiber reinforced bismaleimide resin composites via selective cleavage of imide bonds

Carbon fiber reinforced bismaleimide resin (CF/BMI) composites are widely used in aerospace field due to their high thermal stability, chemical resistance and excellent mechanical properties. With the large-scale application of CF/BMI composites, it is inevitable to produce a lot of solid wastes, which have a serious impact on the environment, so people have to recycle waste CF/BMI composites. In view of the physical and chemical properties of BMI resin, we developed a green and friendly chemical recovery method of CF/BMI composites by selectively breaking imide bonds for controlled chemical degradation of BMI resin. In 5 wt% NaOH/H2O reaction system, the controlled chemical degradation of CF/BMI composites can be realized by selective cleavage of imide bonds, and the 4,4′-Diaminodiphenyl methane (DDM) and 2,2′,2″,2‴-((methylenebis(4,1-phenylene))bis(azanetriyl))tetrasuccinic acid (MBTA) can be recovered, and the carbon fiber (CF) can be recycled at the same time. Under the optimal reaction conditions, the yields of DDM and MBTA reached 6.7 wt% and 27.9 wt% at 180 °C for 8 h, respectively. Meanwhile, CF in CF/BMI composites can be completely recovered, and the tensile strength of recovered carbon fiber (rCF) is about 97.6% of that of virgin carbon fiber (vCF). This work provides a very promising strategy for the recycling of CF/BMI composites. The high value-added CF and chemicals (DDM and MBTA) can be recovered by controlled degradation of CF/BMI composites via selective cleavage of imide bonds.