Pyrolysis Of Resin Research Articles

Catalytic pyrolysis upcycling of waste thermosetting epoxy resin into fire‐retardant additive

AbstractThis research introduces a low‐temperature catalytic‐assisted pyrolysis method for recycling waste thermosetting epoxy resins, transforming them into an efficient fire‐retardant additive for new epoxy resin formulations. In this study, we demonstrate that boric acid (BA) can significantly reduce the temperature required for epoxy resin (EP) pyrolysis, resulting in degradation products containing boron atoms that can act as a fire‐retardant additive. The impact of 5%–20% content of recycled EP (R‐EP) on the curing process, thermal stability, fire retardancy, and mechanical properties of the new EP was comprehensively investigated. The TGA results show that adding BA to epoxy resin at a 1:4 BA:EP ratio significantly reduces pyrolysis temperature. Neat EP degrades in two stages in 341°C and 557°C, while EP with BA degrades in three stages, starting below 120°C and peaking around 142°C. The results demonstrated an outstanding effect of incorporating 20% R‐EP on the char formation and fire retardancy of the new EP, surpassing the performance of 20% triphenyl phosphate (TPP), a commercially available fire retardant. The storage modulus for neat EP is 1510 MPa, increasing to 2280 MPa with EP/R‐EP 20%, indicating enhanced rigidity. Addition of R‐EP raised glass transition temperature (Tg) of the epoxy resin up to 38°C, indicating highly cross‐linked structures compared to TPP‐modified EP, which shows lower Tg values.

Improving the Oxidation Resistance of Phenolic Resin Pyrolytic Carbons by In Situ Catalytic Formation of Carbon Nanofibers via Copper Nitrate.

Phenolic resin pyrolytic carbons were obtained by catalytic pyrolysis of phenolic resin at 500 °C, 600 °C, 700 °C, and 800 °C for 3 h in an argon atmosphere using copper nitrate as a catalyst precursor. The effects of copper salts on the pyrolysis process of phenolic resin as well as the structural evolution and oxidation resistance of phenolic resin pyrolytic carbons were studied. The results showed that copper oxide (CuO) generated from the thermal decomposition of copper nitrate was reduced to copper (Cu) by the gas generated from the thermal decomposition of the phenolic resin. Carbon nanofibers with tapered structures were synthesized by Cu catalysis of pyrolysis gas at 500-800 °C. The catalytic pyrolysis of phenolic resin with Cu increased the graphitization degree and reduced the pore volume of the phenolic resin pyrolytic carbons. The combined action improved the oxidation resistance of phenolic resin pyrolytic carbons.

Cationite synthesis using anthracene extracted from pyrolysis resin by-products: A sustainable approach for production of efficient metal adsorbent

Keeping sustainable waste management and sustainable economy in view, this study investigated the synthesis of a novel polymethyleneanthracene sulfoacid cationite, derived from anthracene extracted with high efficiency (97 % purity) from pyrolysis resin byproducts (a Ustyurt gas-chemical complex). The successful sulfonation of anthracene yielded a substantial amount of the desired product (22.96 g), with a notable reaction efficiency of 82 %. Infrared spectroscopy confirmed the structure of anthracene and its sulfonated derivative, revealing characteristic absorption bands consistent with those of aromatic compounds. Thermogravimetric analysis revealed the thermal stability of the material at temperatures up to 600 °C. The elemental composition, ascertained through EDS, quantified the elements as carbon (65.43 ± 0.05 %), oxygen (22.44 ± 0.05 %), sodium (4.13 ± 0.01 %), and sulfur (8.00 ± 0.01 %). SEM images revealed a highly porous material structure, which is advantageous for ion exchange applications, particularly metal adsorption. Compared to commercial KU-2–8 cationite, the synthesized material had a lower mass density (650–720 g/dm³), a higher humidity content (62.5 %), and a larger comparative size (4.8 cm³/g). The general static exchange capacitance was 475–490 mg-eqv/g, which is slightly lower than the commercial standard of 500–520 mg-eqv/g. These findings indicate that the synthesized cationite has promising potential for ion exchange applications because of its competitive physical and chemical properties.

Characteristics of granulated activated carbon from a mixture of plant raw material waste

Relevance. The need to increase the use of renewable energy sources in the economy to reduce the harmful effects on the environment. Aim. To assess the possibility of obtaining by the thermochemical method high-quality carbon adsorbents from a granular mixture of various wastes of plant origin. Objects. Samples of illiquid lumpy birch wood, walnut shells, sunflower seed husks, flax fires, anthracite coal. Methods. Physical experiments: conductive pyrolysis, water-steam activation and differential thermal analysis. The ash content and moisture content of the samples were determined according to SS R 56881-2016 and SS 33503-2015. Nitrogen adsorption isotherms were measured using a NOVA-1200e analyzer. The equilibrium activity for toluene was determined according to SS 8703-74, the adsorption activity for iodine was determined according to SS 6217-74. The determination of the density of the granules was carried out according to SS 15139-69. Results. The authors have established rational parameters for obtaining carbon adsorbents from granules of vegetable raw materials. The specific yield of pyrolysis products of a mixture of vegetable raw materials with pyrolysis resin was determined. The specific yield of carbonization products of the granular compacted mass showed an increase of 25% in comparison with the non-compacted mixture of vegetable raw materials. Rational parameters for obtaining activated carbon with the highest adsorption capacity are granules with a density of 1200 kg/m3 with a degree of burnout of the carbonization product of 70%. It was established that the obtained samples of adsorbents from granules of plant raw materials have high adsorption characteristics comparable to activated carbons obtained from fossil raw materials.

Investigation on laser paint stripping of CFRP: Morphological evolution, damage mechanism, and adhesive performance

Damage to the substrate hinders the application of laser paint stripping (LPS) on carbon fiber reinforced polymers (CFRP), but the damage mechanism is currently unknown. In this paper, the LPS characteristics of CFRP, such as paint stripping depth, surface morphology and dynamic behavior, are firstly obtained. Subsequently, the surface damage mechanism of CFRP is discussed in detail by theoretical analysis and finite element method, and the effect of substrate damage on adhesive properties is investigated. The results show that it is difficult for LPS to obtain a complete surface free of paint residue. The strong laser plasma impact and resin pyrolysis pressure cause the resin to crack and flake before the paint is fully ablated. The carbon fiber then breaks and are thrown outward by heat and forces, and the surface with slightly fracture of the fiber will facilitate bonding with the paint.

Carbon fiber recovery from carbon fiber reinforced polymer matrix composite by microwave pyrolysis

The recovery of high-value carbon fibers (CFs) from carbon fiber-reinforced polymers (CFRP) is essential for advancing sustainability goals. In this study, CFs were extracted from CFRP using a microwave pyrolysis method known for its efficiency and environmental friendliness. The pyrolysis process was optimized through the response surface methodology to minimize carbon residue accumulation on the CFs' surface. The microwave pyrolysis of CFRP was simulated using COMSOL software to analyze temperature distribution patterns. The optimal parameters for microwave pyrolysis were determined as follows: a temperature of 543.7 °C, a holding time of 22.8 minutes, and a microwave power of 840.9 W, resulting in a residual carbon rate of only 3.7 %. Scanning electron microscopy (SEM) examination revealed no visible surface damage to the CFs. Analysis using X-ray diffraction (XRD) and Raman spectroscopy indicated a slight reduction in the crystallinity and graphitization level of the CFs due to the presence of deposited carbon. Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) results suggested increased oxygen-containing functional groups. The comparative microstructural analysis between the pyrolyzed and pristine CFs showed no significant disparities. These results demonstrate the successful recovery of CFs through rapid resin pyrolysis in CFRP using microwave irradiation.

Effect of Precursor Solvent on the Carbon Micro-Structures Derived from Spray Pyrolysis of Pine Resin (Gondorukem): Preliminary Study

Carbon materials have been widely used in various fields. This study aimed to produce carbon using spray pyrolysis with pine resin (gondorukem) as the precursor and different solvents, namely gondorukem-acetone (GAC), gondorukem-ethyl acetate (GEA), and gondorukem-dichloromethane (GDC). The precursor was prepared in a 1:8 (m/v) ratio, and the spray pyrolysis method was employed by heating the atomized precursor solution in the heating zone of a tube furnace. The atomization precursor was infused with nitrogen gas at a rate of 1 l/min with furnace temperature set at 1000°C with heating times of 5, 10, and 20 mins. The carbonaceous materials produced from the pyrolysis were collected on the wire mesh 1000 that was put on a stainless pipe. Carbon that has been coated on the wire mesh 1000 was analyzed using the optical microscope (OM). The physical properties and morphology of the synthesized carbonaceous material were analyzed using field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), Raman, and Brunaur-Emmett-Teller (BET). Based on FE-SEM analysis, the particle size of the GAC sample has an average of 283.58 nm and the highest carbon content, which reached an average of 97.312 At%. GAC samples had the lowest disorder properties in the Raman spectroscopy test, with the value of ID/IG reaching 0.795764. The functional groups observed were C–H stretching at 2920.49 cm-1, N–H bending at 1629.07 cm-1, and C–O stretching at 1159.70 cm-1. Based on carbon content, disorder properties, and functional group stabilization, carbon from the GAC precursor provides the ideal characteristics to be used as a filter material in medical masks. Meanwhile, based on BET testing, the carbon materials from GEA have the ideal material morphological properties to be used as a filter in medical masks. Spray pyrolysis is an efficient method for producing carbon materials, and the use of gondorukem as the precursor shows great potential for various applications.

Selection strategy of curing depth for vat photopolymerization 3D printing of Al2O3 ceramics

Vat photopolymerization (VPP) 3D printing technology allows the fabrication of complex ceramic structure components through the layer-by-layer stacking strategy. The curing depth is a crucial parameter for the stacking process, as it directly impacts the printing quality. Furthermore, this parameter exerts a profound effect on the final quality of the printed part. However, there is currently a lack of comprehensive research on how the curing depth affects VPP ceramic 3D printing. This study aims to thoroughly evaluate the impact of curing depth parameters on critical aspects of the 3D printing process, including the forming accuracy, surface quality, monomer conversion, resin pyrolysis, interlayer defects, and mechanical properties. The results of our investigation clearly demonstrate the significant influence of curing depth on the precision and performance of VPP 3D printed ceramic parts. Ceramic samples produced with higher curing depth exhibited superior surface quality (Ra<1.6 μm) but lower forming accuracy. Increasing the curing depth improved interlayer adhesion but excessive depth led to a decreased monomer conversion content from 5.2 % to 2.0 % and an internal stress in the green body. Moreover, increasing the curing depth intensified the pyrolysis process and increased the propensity for cracks forming, as confirmed by simultaneous thermal analysis and microstructure observations. The flexural strength of the sintered samples reached its maximum value of 630 MPa at three times the printing layer thickness. This study provides valuable insights for selecting appropriate curing depth parameters in VPP ceramic 3D printing.

Effect of sintering temperature and silicone resin content on in-situ formed SiC nanowire reinforced ceramic shells

The silicone resin was used to modify ceramic shells for investment casting. SiC nanowires were in-situ formed by the carbothermal reduction method. The pyrolysis of silicone resin and the formation mechanism of SiC nanowires were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results showed that the shells had the maximum sintering bending strength of 7.35 MPa when the silicone resin content and the sintering temperature were 20 wt% and 1300 °C, respectively. The phase of β-cristobalite during the transformation from amorphous SiOC to fused SiO2 after the pyrolysis of silicone resin impacted the bending strength. In addition, the iron oxide in corundum sand was used as the catalyst in the VLS mechanism to form the ball-stick-shaped SiC nanowires at 1000 °C–1100 °C. However, the necklace-like and rod-like SiC nanowires were formed at 1200 °C–1300 °C in the VS mechanism, which replaced the VLS mechanism.

Adaptive Force Field Parameter Optimization for Expanding Reaction Simulations within Wide-Ranged Temperature.

Large-scale and long-term simulation of chemical reactions are key research topics in computational chemistry. However, there are still difficulties in simulating high-temperature reactions, such as polymer thermal decomposition. Herein, we introduce an adaptive potential parameter optimization framework designed to automatically fine-tune parameters, and the application of it to optimize ReaxFF parameters enhances the accuracy of chemical reaction simulations conducted at experimental temperatures. To achieve this, we leverage the power of Random Forests and interpretable machine learning techniques that enable the identification and selection of parameters that exert a substantial influence on the target attribute. By training deep neural network (NN) models, we established optimized parameter associations with reference properties. We train deep neural network (NN) models to establish the relationship between the optimized parameters and reference properties. We employ a Genetic Algorithm (GA) to utilize the surrogate NN model and the quantum mechanical targets to speed up the search for the optimal parameters. Our simulation results of resin pyrolysis show that the adaptive optimized ReaxFF can predict the peak temperature more accurately and obtain reasonable product composition under conditions that more closely resemble experimental scenarios. This work facilitates advances in force field parameter optimization for more accurate and universal reaction simulations.

Assessment of continuous laser ablation model for lightweight quartz fiber reinforced phenolic composite

AbstractA comprehensive investigation into the interaction between a continuous wave (CW) laser and lightweight quartz fiber reinforced phenolic (LQFRP) composite would provide valuable insights into the characteristics and performance of ablation. To simulate the CW laser ablation of LQFRP composite, a 2D symmetrical element model was developed, incorporating the heat conduction equation, resin pyrolysis mechanism, and deformed geometry module. This model was the first to examine the internal pyrolysis degree and gas flow field of LQFRP composite under CW laser irradiation, and its predictions were in reasonable agreement with experimental measurements. Additionally, the model was used to simulate CW laser ablation with varying spot sizes and power densities. The results revealed that during the laser ablation process, an internal high‐pressure zone formed on the side of the ablation hole. The volatilization of SiO2 was identified as the dominant dissipation mechanism for material removal. The width of the ablation hole was positively correlated with the laser spot size, while the depth of the ablation hole was positively correlated with the laser power density.Highlights The model first studied the internal pyrolysis degree and flow field of LQFRP composite under laser irradiation. The volatilization of SiO2 was identified as the dominant dissipation mechanism for material removal. An internal high‐pressure zone formed on the side of the ablation hole during the laser ablation process. The width of the ablation hole was positively correlated with the laser spot size, while the depth of the ablation hole was positively correlated with the laser power density.

The effect of graphitization degree of carbon and Si─O─C network on the electrochemical performance of SiOC anodes

AbstractSilicon oxycarbide (SiOC) is a promising anode material for lithium‐ion batteries, owing to the high capacity and superior structural stability. However, the application of SiOC anode is limited by its low conductivity and poor rate performance. Here, SiOC anodes were prepared by the pyrolysis of silicone resin (RSN‐217) at different temperatures (700, 850, 1000, and 1150° C), and the effect of graphitization degree and Si─O─C network on the electrochemical performance of SiOC anodes was investigated. The elemental and structural characteristics of the pyrolyzed SiOC ceramics at different temperatures were inspected using a broad spectrum of characterization techniques, and electrochemical performance testing methods, such as cyclic voltammetry and galvanostatic charge/discharge, were conducted on SiOC anode. SiOC‐1000 showed excellent electrochemical performance due to the highest graphitization degree of free carbon phase and the highest content of SiO2C2 and SiO3C units. Considerable research effort laid a foundation for exploring the lithium storage mechanism of SiOC anode.

Chemical kinetics of SARA fractions pyrolysis: Resins

This work presents a predictive and generally applicable approach to resin pyrolysis modeling. Resins extracted from heavy fuel oil 380 (HFO) and vacuum residue oil (VRO) were tested for elemental composition, chemical structure, thermal degradation behavior, and distribution of pyrolysis products using different state-of-the-art experimental techniques. The in-house experiments, together with extensive literature research, guided the formulation of five pseudo-components for the definition of a fuel surrogate. The atomic ratios of the surrogate molecules were defined to be able to replicate the elemental composition of all the data with their linear combination. This approach makes the model flexible and readily applicable to any resin sample just by knowing its elemental composition. The kinetics mechanism was developed by coupling each pseudo-component with a decomposition reaction pathway. The choice of the kinetics parameters was driven by the experimental information available. The model presented a satisfactory agreement with experimental data used for the validation. The kinetic model represents a step of a more comprehensive project aimed at reconstructing the chemical kinetics of heavy and residual oils as a combination of their saturate, aromatic, resin, and asphaltene (SARA) fractions.

Ablation of advanced C/C-ZrC-SiC leading edge composites

To mitigate interphase degradation and improve the mechanical and ablation properties of leading edge shaped C/C-ZrC-SiC composites fabricated by reactive melt infiltration, a tailored SiC-C interphase composed of SiC, gas pyrolysis carbon and phenolic resin pyrolysis char was introduced. The SiC-C interphase can effectively protect the carbon fiber from high-temperature melt erosion, improving the flexural strength of the composites by 98%. The mass and thickness change rates of the leading edge composites were 2.96 ± 0.04 µm/s and − 0.42 ± 0.04 mg/s, respectively. The better ablation performance was attributed to the synergistic effect of dense and stabilized Zr-Si-O oxide layer formation and heat transfer.

Pyrolytic performance and kinetics study of epoxy resin in carbon fiber reinforced composites: Synergistic effects of epoxy resin and carbon fiber

Pyrolysis is recognized as a sustainable approach for recycling carbon fiber reinforced polymers (CFRP), ensuring enhanced process efficiency and resource utilization. To unveil the pyrolysis mechanism of epoxy resin and its synergistic interaction with carbon fiber in different scenarios, we conducted pyrolysis experiments on pure epoxy resin diglycidyl ether of bisphenol A cured with 4,4'-Diaminodiphenylmethane (C-epoxy), as well as three kinds of carbon fiber-resin mixtures, using TG and Py-GC/MS techniques. Isoconversional analysis (Friedman method) of C-epoxy degradation revealed three reaction stages within the temperature range of 280–540 °C, each corresponding to activation energies of 158 kJ/mol at α = 5%, 179–190 kJ/mol at the plateau of α = 10–60%, and 190–236 kJ/mol for α values surpassing 60%. The multi-Gaussian distributed activation energy model (DAEM) aptly characterized C-epoxy’s thermal decomposition, featuring two Gaussian peaks with similar contributions of 0.58 and 0.42, and activation energy distributions of 217.76 ± 3.92 kJ/mol and 233.36 ± 21.42 kJ/mol, respectively, which are close to the activation energies from isoconversional analysis at α = 10–60% and α > 60%, respectively. The presence of carbon fiber significantly influenced the kinetic parameters of epoxy resin pyrolysis, with the extent of change linked to the mixing methodology applied. Notably, carbon fiber decreased the activation energy of the reaction while accelerating the rate of weight loss. However, the synergistic effects vary depending on different synergistic scenarios. By analyzing the product distribution obtained through an analytical pyrolyzer coupled with a gas chromatography–mass spectrometry set-up (Py-GC/MS), we proposed a pyrolysis mechanism for epoxy resin, encompassing three key stages: cleavage of N–C and NC–COH bonds, phenolic O–C and vicinal C–C bonds, and disruption of the isopropylidene bridge on bisphenol A. The influence of carbon fiber on epoxy resin pyrolysis product distribution was relatively modest, manifesting predominantly within the mixture obtained by premixing before curing. Here, carbon fiber exhibited a dual effect, inhibiting oxygen-containing diphenyl products while promoting oxygen-containing monophenyl products. Ultimately, our study provides essential kinetic data for multidimensional simulation and theoretical guidance pertaining to the pyrolysis recycling of widely used carbon fiber-reinforced epoxy resin composites.

Thermal and mechanical damage to carbon fibre reinforced composites with metallic fasteners under lightning strike

In this study, lightning strike (LS) damage to carbon fibre reinforced composites (CFRCs) with metallic fasteners was investigated by simulated LS tests and finite element (FE) model. First, the LS damage mode and mechanism of a single-lap composite joint and a CFRC laminate with a metallic rivet were studied. Resin pyrolysis was found on the surface but severe delamination was evident inside the composites due to a gas explosion caused by the sudden burn-off of polymer matrices and thermal expansion inside the laminate. Then, the effect of rivet spacing on the LS damage to CFRCs was examined. The results showed that the damaged area was significantly reduced because the surrounding rivets effectively suppressed impact-induced delamination and consumed more electrical energy. The results also showed that large-area delamination across the rivets was achieved due to high potential at the surrounding rivets when the spacing was short but dynamic deflection was confined by the surrounding rivets. In contrast, delamination was only concentrated at the central rivet when the spacing was large, which can be ascribed to fewer currents flowing into the surrounding rivets, and the confinement of the adjacent rivets was less significant.

Life cycle analysis on sequential recovery of copper and gold from waste printed circuit boards

Informal recycling activities of waste printed circuit boards, such as pyrolysis and landfilling, cause severe environmental harm to society. Pyrolysis of resin and polymer fraction leads to the generation of toxic effluents, and landfilling causes the leaching of heavy metals into the groundwater. A sustainable and eco-friendly way to recover base and precious elements will be an economically attractive option. Current research studied the cradle-to-gate environmental impacts of the sequential recovery of copper and gold through delamination, leaching, solvent extraction, electrowinning and cementation from waste printed circuit boards with the help of life cycle assessment.GaBi software was utilized to assess environmental impacts such as global warming, abiotic depletion (fossil), acidification potential and human toxicity potential during the process. Inventory data was collected by conducting several experiments and from optimizing parameters for recycling and separating 4.53 g of copper and 2.25 mg of gold from 16 g of component-free waste printed circuit boards. Results indicate that the chemical pre-treatment or delamination process for separating metal clads from the non-metallic fraction is primarily involved in the impact category. The higher impact during delamination is due to electricity consumption. The proposed study also corroborates the industrial viability of recycling valuable metals from waste printed circuit boards to minimize the environmental impacts. The outcomes of this work could be beneficial in creating the environmental guiding principle for WPCBs recycling plants.

Co-pyrolysis of paper-laminated phenolic printed circuit boards and calcium-based additives in fixed and fluidized bed reactors

This study compares the impact of the calcium-based additives and the pyrolyzer on the recovery and the halide content of the oil produced from the pyrolysis of paper-laminated phenolic resin printed circuit boards (FR2-PCB). The preliminary experiments showed that the maximum liquid recovery (40.6%) was achieved in a fluidized bed pyrolyzer containing a 50:50 mixture of CaO and Ca(OH)2 operating at T = 620 °C and PCB-to-additive ratio (FR2/A) = 5.4 g/g for 22 min. Extra tests were then carried out under these conditions in fixed and fluidized bed pyrolyzers to separately explore the impact of CaO, Ca(OH)2, and CaO + Ca(OH)2 on the liquid recovery (LR) and the halogen content of the non-solid products. In the fluidized bed, LR in the presence of CaO, Ca(OH)2, and CaO + Ca(OH)2 was 34.5%, 41.2%, and 38.9 wt%, respectively. The fraction of phenolic compounds in the pyrolysis oil ranged from 86% to 93%, about 1–3% higher than the corresponding values in the fixed bed. Using additives led to lower halide content in the pyrolysis oil of the fluidized bed than that of the fixed bed. However, the opposite trend was observed in the absence of additives. Regardless of the type of pyrolyzer, Ca(OH)2 was more successful than CaO in increasing LR, whereas CaO was more effective than Ca(OH)2 in pyrolysis oil dechlorination. Co-pyrolysis of FR2-PCB and CaO + Ca(OH)2 in a fluidized bed reactor was identified as a practical approach to enhance the recovery of pyrolysis oil comprising only 5% of the original halogen content of the feedstock.

Synthesis of highly-porous nitrogen-doped carbon materials by pyrolysis of melamine-formaldehyde resin using a hard template

The use of nitrogen-doped carbon materials as electrodes in supercapacitors is a promising area of research. In this study highly-porous nitrogen-containing carbon materials were obtained by pyrolysis of melamine formaldehyde resin in the presence of nanocrystalline MgO as a hard template that was washed off after the pyrolysis. Magnesium citrate was used as a precursor for the synthesis of the template agent in situ during the pyrolysis of the resin. The obtained materials were characterized by X-ray diffraction, BET nitrogen adsorption method and Raman spectroscopy. The presence of nitrogen in the amount of 4 atomic percent was proved by XPS spectroscopy. The specific surface area was found to increase monotonically from 10 to 1300 m2/g with an increase in the content of magnesium citrate in the initial mixture. The samples showed high capacitance of 120 F/g in 1 M H2SO4 electrolyte and can be used in supercapacitors.

Study on oxidation behavior during process of recycling carbon fibers from CFRP by pyrolysis

The study utilized a pyrolysis method to recycle carbon fibers from carbon fiber reinforced polymer (CFRP), followed by oxidation to remove pyrolysis carbon. The obtained recycled carbon fibers had good mechanical properties, and the tensile strength could reach 96.2% of the virgin carbon fibers under the optimal process conditions. The recycled carbon fibers displayed similar chemical structure and graphitization degree as the virgin carbon fibers, and showed better wettability with epoxy resin. In addition, density functional theory (DFT) calculations were also employed to analyze the mechanism of pyrolysis carbon oxidation removal. The results showed that the adsorption energy of oxygen on pyrolytic carbon and the reaction activation energy were lower than those of carbon fibers, indicating that pyrolytic carbon was more easily oxidized than carbon fibers. This allowed pyrolytic carbon to be removed by oxidation at relatively low temperatures and preserved the integrity of carbon fibers, thus ensuring that the carbon fibers also maintained excellent mechanical properties after recycling. This study helps to reveal the oxidation mechanism of resin pyrolysis carbon, providing technical support for efficient and clean recycling of carbon fibers.