Original Carbon Fiber Research Articles

Continuous carbon fiber recycling technology using the electrolytic sulfuric acid method

Our objective is to achieve the societal implementation of the Circular Economy Program for Automobile Carbon Fibers. This involves recycling carbon fibers sourced from carbon fiber reinforced plastics/carbon fiber reinforced thermoplastics (CFRP/CFRTP) discarded from automobiles and reintegrating them into the manufacturing processes of automobiles. Although, the existing carbon fiber recycling technology recycles the carbon fiber into a finely chopped state; it is not the original continuous carbon fiber product. A novel recycling technology is elucidated herein, referred to as the electrolytic sulfuric acid method (ESAM). The ESAM recycles carbon fibers by decomposing only the resin component of CFRP/CFRTP into CO2 and water using oxidative active species generated by electrolytic sulfuric acid. This method can (1) be applied to all resins, (2) maintains strength of the recycled carbon fibers, and (3) regenerates continuous carbon fibers. Moreover, it is the only technology applicable to CFRP pressure tanks. The successful recycling of continuous carbon fiber from pressure tanks has been achieved, enabling the production of new tanks and unidirectional CFRTP tape. This technology recycles the original continuous carbon fiber product, thus enabling a “close” resource circulation cycle. We have not yet confirmed the number of times recycling can be performed. However, according to the method described in this paper, the recycling process can yield continuous carbon fibers without a decrease in physical properties. Therefore, theoretically, it becomes possible to recycle indefinitely and revert the fibers to their original state, provided that the strength reduction during product use is not a significant consideration.

Multifunctional Carbon Fiber Reinforced C/SiOC Aerogel Composites for Efficient Electromagnetic Wave Absorption, Thermal Insulation, and Flame Retardancy.

Carbon fiber composites have great application prospects as a potential electromagnetic (EM) wave-absorbing material, yet it remains extremely challenging to integrate multiple functions of EM wave absorption, mechanical strength, thermal insulation, and flame retardancy. Herein, a novel carbon fiber reinforced C/SiOC aerogel (CF/CS) composite is successfully prepared by sol-gel impregnation combined with an ambient drying process for the first time. The density of the obtained CF/CS composites can be controlled just by changing sol-gel impregnation cycles (original carbon fiber felt (S0), and samples with one (S1) and two (S2) impregnation cycles are 0.249, 0.324, and 0.402 g cm-3, respectively), allowing for efficient tuning of their properties. Remarkably, S2 displays excellent microwave absorption properties, with an optimal reflection loss of -65.45dB, which is significantly improved than S0 (-10.90dB). Simultaneously, compared with S0 (0.75 and 0.30MPa in the x/y and z directions), the mechanical performance of S2 is dramatically improved with a maximum compressive strength of 10.37 and 4.93MPa in the x/y and z directions, respectively. Moreover, CF/CS composites show superior thermal insulation capability than S0 and obtain good flame-retardant properties. This work provides valuable guidance and inspiration for the development of multifunctional EM wave absorbers.

Synergetic surface modification of 3D braided carbon fiber-reinforced composites for enhancing mechanical strength

Excellent interfacial bonding contributes to the reduction of internal defects in composites for enhancing the mechanical properties of the 3D braided carbon fiber reinforced composites. In this paper, the effects of plasma and strong acid treatment on the surface morphology, chemical composition, and surface free energy of original carbon fiber braid (CFB) were investigated in detail to reveal the mechanism of synergetic enhancement of surface wettability of carbon fiber by plasma and strong acid. The results showed that the synergetic effect of plasma and strong acid produced significantly improved the resin/fiber interfacial bonding. The interfacial shear strength (IFSS) of the carbon fiber braided reinforced composites (CFBC) treated with the synergetic treatment was 64.6% higher than that of the untreated fiber reinforced composites. The improved interfacial properties increase the polar functional groups on the fiber surface to promote the formation of mechanical interlocking caused by Cassie-Baxter(CB) and Wenzel(WZ) leaps of liquid resin on the fiber surface, and this was verified by molecular dynamics(MD) simulations of carbon fiber-resin interfacial wetting. The simple and effective synergetic reinforcement strategy proposed in this paper can effectively regulate the interfacial bonding and is applicable to the optimal design of original carbon fiber braided reinforced composites.

Highly sensitive voltammetric determination of Allura Red (E129) food colourant on a planar carbon fiber sensor modified with shungite

This article presents an original planar carbon fiber electrode (PCFE), in which shungite (SHU) is used as a modifier for the first time. Shungite is a unique natural nanostructured composite consisting of carbon in the form of aggregated graphene stacks, oxides of silicon, titanium, aluminum, iron, magnesium, potassium, etc. Macro- and micro-elements, biologically active components that are present in shungite provide it with attractive antioxidant properties, make it a biocompatible and environmentally friendly material that meets the principles of green chemistry. A unique supramolecular structure of shungite carbon presents a multilayer globular-cluster formation with mesopores in the internal volume. It determines specific physical, chemical, catalytic, and adsorption properties of shungite. Carbon fiber with an irregular 3D structure was used as an effective electrode platform for strong immobilization of shungite. The PCFE was fabricated using a simple and scalable hot lamination technology that produces very low cost flexible planar electrodes. The sensor (SHU/PCFE) was characterized by scanning electron microscopy; electrochemical impedance analysis; cyclic, differential-pulse and stripping voltammetry. The SHU/PCFE showed a 2.5-fold increase in the electroactive surface area, a 1.8-fold decrease in the electron transfer resistance compared with the bare PCFE. Under optimal experimental conditions and preconcentration at +0.2 V (vs. Ag/AgCl) 180 s, the developed sensor allowed the quantification of Allura Red in the ranges of 0.001–0.1 and 0.1–2 μmol L−1 with an extremely low detection limit of 0.36 nmol L−1. Moreover, this convenient and cost-effective sensor also has good repeatability, stability and anti-interference ability. The interfering effect of sweeteners and preservatives in the determination of Allura Red does not exceed 3.6%. The practical application of the SHU/PCFE was demonstrated using drink samples, lollipops and pharmaceuticals.

Performance analysis of recycled carbon fiber under recycling process parameters optimized using response surface methodology

The recycling of high-performance carbon fiber from carbon fiber-reinforced polymer (CFRP) wastes have great economic value and environmental significance. Based on the principle of thermally activated oxide semiconductors, the resin matrix decomposition of process model was established by response surface methodology (RSM). The morphology, elements, functional groups and mechanical properties of recycled carbon fiber were investigated. The results indicated that the degradation was positively correlated with time and temperature, and the degree of influence was significant, the effect of O2 flow rate and concentration were not significant. The influence of process parameters on resin decomposition was as follows shown: temperature > time > O2 concentration > O2 flow rate. The actual degradation was 96.12 wt.% under temperature of 520°C, time of 23 min, O2 concentration of 80% and flow rate of 180 mL/min. The recycled carbon fiber (rCF) was compared with the original carbon fiber the surface roughness of rCF was increased, and without carbon deposition on the surface. The content of C element and C–C bond on the surface of rCF were significantly increased, and functional group of COOH was produced. The tensile strength of rCF was maintained above 99%, the Young’s modulus was maintained at 92%, and the interfacial shear strength was maintained at 85%.

137 Analysis of Debris Generated During the Process of Cutting and Grinding of Carbon Fibers-Reinforced Plastics

Abstract Carbon fiber reinforced plastics (CFRP) is a leading functional material with superior strength and low mass density compared to metal. Recently, due to its excellent property, it has spread to a wide range of fields from sporting goods, such as golf clubs and fishing rods, to aerospace products. However, there is concern that debris (microparticles) is easily released in the processing process of CFRP. The present study investigated the ambient level, size, and shape of particles generated from CFRP during various machining processes in an occupational setting. The size and shape of particles were observed using scanning electron microscopy (SEM) and their chemical compositions were also analyzed using energy dispersive spectroscopy (EDS). The majority of debris from CFRP was cylindrical with a diameter comparable to the diameter of the original carbon fiber, suggesting transversally split carbon fiber. However, some of the debris was fibrous, length >5 μm, width 3, suggesting longitudinally split carbon fiber. These fibrous fragments were morphologically compatible with the WHO definition of respirable fibers. The particles in the working environment were also monitored with a real-time monitoring device, NanoScan SMPS Model 3910. Measurement by real-time monitoring device showed that not only microparticles but also smaller particles were released in the processing process of CFRP. These particles are probably breakdown elements of the epoxy thermoset polymer (resin) in CFRP. The potential hazard of debris from CFRP in the processing process in an occupational setting and risk assessment is needed for the safe handling of CFRP.

Mechanical Behaviors of Microwave-Assisted Pyrolysis Recycled Carbon Fiber-Reinforced Concrete with Early-Strength Cement

This study aimed to investigate the mechanical performance of early-strength carbon fiber-reinforced concrete (ECFRC) by incorporating original carbon fiber (OCF), recycled carbon fiber (RCF), and sizing-removed carbon fiber (SCF). Compressive, flexural, and splitting tensile strength were tested under three fiber-to-cement weight ratios (5‱, 10‱, and 15‱). The RCF was produced from waste bicycle parts made of carbon fiber-reinforced polymer (CFRP) through microwave-assisted pyrolysis (MAP). The sizing-removed fiber was obtained through a heat-treatment method applied to the OCF. The results of scanning electron microscopy (SEM) analysis with energy dispersive X-ray spectrometry (EDS) indicated the successful removal of sizing and impurities from the surface of the RCF and SCF. The mechanical test results showed that ECFRC with a 10‱ fiber-to-cement weight ratio of carbon fiber had the greatest improvement in its mechanical strengths. Moreover, the ECFRC with 10‱ RCF exhibited higher compressive, flexural, and splitting tensile strength than that of benchmark specimen by 14.2%, 56.5%, and 22.5%, respectively. The ECFRC specimens with a 10‱ fiber-to-cement weight ratio were used to analyze their impact resistance under various impact energies in the impact test. At 50 joules of impact energy, the impact number of the ECFRC with SCF was over 23 times that of the benchmark specimen (early-strength concrete without fiber) and was also greater than that of ECFRC with OCF and RCF.

Investigation of the effect of thermal emf in carbon fibers

The article presents the result of a study of the occurrence of the thermoelectric effect in contact "modified carbon fiber - the original carbon fiber". The description of the method of modification of carbon fiber by pulsed current is given. The supposed physical process of this phenomenon is shown. The possibility of implementing this effect in rocket and space technology is being considered.

Mechanical behavior of different fiber lengths mix-proportions carbon fiber reinforced concrete subjected to static, impact, and blast loading

Impact and blast wave loadings act as high instant energy and might cause damage to reinforced concrete infrastructures. This research aims to investigate the effect of using different length proportions of carbon fiber on the mechanical behaviors of concrete. Moreover, in this study, original carbon fiber and sizing-removed carbon fiber were added into concrete with different mix-proportions. The sizing on the carbon fiber surface was removed by using heat-treated method. In addition, the carbon fiber was dispersed by a high-pressure air compressor. Lengths of 12 mm and 24 mm carbon fibers were used in different mix-proportions to find the highest mechanical strength of carbon fiber reinforced concrete (CFRC) under a 1% fiber-to-cement weight ratio. Compressive, flexural, and impact tests were conducted on CFRC specimens. The CFRC specimen with 50% 12 mm and 50% 24 mm sizing-removed carbon fiber attained the highest impact resistance, and it also had the best performance under blast wave loading compared with the other CFRC specimens. The broken CFRC specimens were examined by an optical microscope to identify the failure mode of the carbon fibers in CFRC specimens. The addition of 50% 12 mm and 50% 24 mm sizing-removed carbon fiber can significantly improve the compressive and flexural strength of reinforced concrete.

Enhancing Thermal Conductivity of Polyvinylidene Fluoride Composites by Carbon Fiber: Length Effect of the Filler.

Thermally conductive polyvinylidene fluoride (PVDF) composites were prepared by incorporating carbon fibers (CFs) with different lengths (286.6 ± 7.1 and 150.0 ± 2.3 µm) via cold pressing, followed by sintering. The length effects of the CF on the thermal conductivity, polymer crystallization behaviors, and mechanical properties of the PVDF composites were studied. The through-plane thermal conductivity of the PVDF composites increased significantly with the rise in CF loadings. The highest thermal conductivity of 2.89 W/(m∙K) was achieved for the PVDF composites containing 40 wt.% shorter CFs, ~17 times higher than that of the pure PVDF (~0.17 W/(m∙K)). The shorter CFs had more pronounced thermal conductive enhancement effects than the original longer CFs at higher filler loadings. CFs increased the storage modulus and the glass transition temperature of the PVDF. This work provides a new way to develop thermally conductive, mechanically, and chemically stable polymer composites by introducing CFs with different lengths.

Design of inherent fire retarding and degradable bio-based epoxy vitrimer with excellent self-healing and mechanical reprocessability

Epoxy resins possess poor flame retardancy and have difficulty in both recycling and reprocess ability which largely limit their application. Herein, two vanillin-based epoxy monomers, shorted as VAD-EP and VDP-EP, containing both imine bonds and inherently fire retarding phosphorus elements, were synthesized via in situ condensation reaction with DDM and addition reaction with DOPO, followed by the epoxidation by epichlorohydrin. Epoxy vitrimer materials were then cured by D230 diamine hardener by adjusting the proportion of VAD-EP and VDP-EP monomer. When the mass ratio of VAD-EP and VDP-EP was 8:2, A8P2-D230 reached the fire retarding UL-94 V0 rating and LOI value of 27.0% with only 0.66% of phosphorus content, this behavior was ascribed to condensed phase and free radical scavenging mechanisms. When the mass ratio was 7:3, the tensile strength and elastic modulus of the A7P3-D230 epoxy were 75.5 MPa and 2.5 GPa, respectively, i.e. 48.6% and 18.8% higher than A10P0-D230 sample. Meanwhile, the material showed high stress relaxation rate, due to the presence of dynamic imine bonds in the topological crosslinking network. As a consequence, the epoxy vitrimer exhibited excellent self-healing capability, reprocessability and degradation behaviors. The biobased epoxy vitrimer was then used to prepare the carbon fibers (CFs) reinforced epoxy composites, results showed that CFs can be completely recycled. Interestingly, the recycled CFs maintain unchanged chemical structure, mechanical properties and morphology as the original CFs.

Carbon Fibers and Graphite as Pore-Forming Agents for the Obtention of Porous Alumina: Correlating Physical and Fractal Characteristics

Porous alumina ceramics with different porosities were prepared via atmospheric pressure sintering using a sacrificial template method with alumina powder as the raw material and carbon fiber (CF) and graphite as pore-forming agents. The effects of the contents and ratios of the pore-forming agents and the aspect ratios of CF on the microstructure, mechanical properties, pore size, and pore-size distribution of the porous alumina samples were investigated. In addition, the surface fractal dimension (Ds) of porous alumina samples with different pore-forming agents was evaluated based on the mercury intrusion porosimetry data. The pore-size distribution of the prepared porous alumina samples showed single, double, or multiple peaks. The pore structure of the samples maintained the fibrous shape of the original CF and the flake morphology of graphite with a uniform pore-size distribution, but the pore structure and morphology were different. With the increase in the content of the pore-forming agent, the porosity of the samples gradually increased to a maximum of 63.2%, and the flexural strength decreased to a minimum of 12.36 MPa. The pore structure of the porous alumina samples showed obvious fractal characteristics. Ds was closely related to the pore structure parameters of the samples when the content of the pore-forming agent was 70 vol.%. It decreased with an increase in the sample porosity, most probable pore size and median pore size, but increased with an increase in the sample flexural strength.

The Use of Carbon Fibers Recovered by Pyrolysis from End-of-Life Wind Turbine Blades in Epoxy-Based Composite Panels.

This work is devoted to evaluating the effectiveness of the recovery of carbon fibers from end-of-life wind turbine blades in the pyrolysis process, and the use of those fibers in the production of flat composite panels. The recovery of carbon fibers from wind turbine blades uses a pyrolysis process at 500–600 °C in a non-oxidizing atmosphere, in such a way that makes it possible to preserve the shape and dimensions of the fibers. Using recycled carbon fibers, flat CFRP sheets with epoxy resin matrix were produced by pressing. Seven different series of samples were tested, which differed in fiber length, fiber orientation, and pressure holding time. The results obtained on the recycled fibers were compared to the original carbon fibers, cut to corresponding lengths. Additionally, one of the series was reinforced with a biaxial fabric. The most favorable pressing parameters are empirically found to be pre-pressing 2 MPa (10 min), and further pressing at a pressure of 7 MPa until the resin completely cross-linked (about 120 min). A number of tests were carried out to demonstrate the usefulness of pyrolytic fibers, including tensile strength of carbon fibers, bending strength, SEM observations, FT-IR, and Raman spectroscopy. The tests carried out on the carbon fibers show that the pyrolysis process used leaves about 2% of the matrix on the surface of the fiber, and the tensile strength of the fibers drops by about 20% compared to the new carbon fibers. The research results show that the use of the recycled carbon fibers in the production of flat composite plates is reliable, and their mechanical properties do not differ significantly from plates made of corresponding original carbon fibers. Composite panels with the pyrolytic fibers (274 MPa) show up to a 35% higher flexural strength than similarly produced panels with the original new carbon fibers (203 MPa), which means that the panels can be used in the production of elements for footbridges, bridges, pipelines, or structural elements of buildings and roofing.

Higher ablative resistance performance of CF-ZrO2/ZrC composites by an in-situ sol-gel method

In the present study, CF-ZrO2/ZrC composites with controllable coating thickness were prepared by an in-situ sol-gel method. Through pretreatment, the carbon fibers surface changed from hydrophobic to hydrophilic and the polar groups on the surface significantly increased, which increased the interface affinity and ensured the stabilities of uniform ZrO2/ZrC coatings preparation. The coating layer increases the thickness of the composites, prolonged the mass and heat transfer on the composites surface. The dense ZrO2/ZrC coating prevents further oxidation of internal C by oxidative gas. As a result, after 4 cycles sol-gel, the mass ablation rate of the composite is decreased from 0.046 to 0.022 mg s−1, under the butane flame for 120s. And the thermal decomposition temperatures are 10.8%–15% higher than those of the original carbon fiber. Thus, this in-situ sol-gel method is a feasible for preparing carbon fiber self-reinforced composites with uniform coating and designable structure, which can effectively improve the ablative resistance ability and thermal decomposition temperature of composites.

Evaluation of graphitization and tensile property in microwave plasma treated carbon fiber

Plasma technology can be used as a green and novel method for the graphitization of carbon fiber. The effect of graphitization time on the main element content along with microstructure of carbon fiber in the plasma treatment process was investigated. It took an extremely short time (less than 100 ms) for the temperature of the system to increase until a relatively stable stage was reached. Furthermore, compared with the original carbon fiber, the increase in the carbon content and graphitization degree of carbon fiber was observed after microwave plasma treatment. Moreover, the original imperfect turbostratic graphite-like structure transformed to an ordered graphite structure with the escape of non‑carbon elements from the disordered region of graphite-like crystallites. With the graphitization time of 180 s and microwave power of 800 W, corresponding to the temperature of 2100 °C, a high graphitization degree (R = 0.61) was observed and the crystallite size was as large as 5.10 nm, which are better than that of M40J and T800H. After 5 mins treatment, the average tensile modulus of samples apparently increased by 23% from 189 GPa to 245 GPa. This work demonstrated that the microwave plasma is an alternative approach for the development of carbon fibers with good microstructure and high graphitization degree.

Factory site analysis of respirable fibers generated during the process of cutting and grinding of carbon fibers-reinforced plastics.

Carbon fibers are used in a variety of industrial applications, based on their lightweight and high stiffness properties. There is little information on the characteristics and exposure levels of debris generated during the factory processing of carbon fibers or their composites. This study revisits the general assumption that carbon fibers or their debris released during composite processing are considered safe for human health. The present interventional study was conducted at a factory located in Japan, and involved on-site collection of debris generated during the industrial processing of polyacrylonitrile (PAN)-based carbon-fiber-reinforced plastic (CFRP). The debris were collected before being exhausted locally from around different factory machines and examined morphologically and quantitatively by scanning electron microscopy. The levels of exposure to respirable carbon fibers at different areas of the factory were also quantified. The collected debris mainly contained the original carbon fibers broken transversely at the fiber's major axis. However, carbon fiber fragments morphologically compatible with the WHO definition of respirable fibers (length: > 5μm, width: < 3μm, length/width ratio: > 3:1) were also found. The concentrations of respirable fibers at the six examined factory areas under standard working conditions in the same factory were below the standard limit of 10 fibers/L, specified for asbestos dust-generating facilities under the Air Pollution Control Law in Japan. Our study identified potentially dangerous respirable fibers with high aspect ratio, which was generated during the processing of PAN-based CFRP. Regular risk assessment of carbon fiber debris is necessary to ensure work environment safety.

Enhancing the electrical insulation of highly thermally conductive carbon fiber powders by SiC ceramic coating for efficient thermal interface materials

Mesophase pitch-based carbon fibers (MPCFs), which have ultrahigh intrinsic thermal conductivity and one-dimensional morphology with high-aspect ratios, can act as excellent fillers for improving the oriented heat dissipation rate of thermal interface materials (TIMs). However, the high electrical conductivity hinders their application in some electronic packaging fields. Herein, a SiC ceramic layer is uniformly and firmly coated on the surface of the powder-like MPCFs by a dynamic chemical vapor deposition method to obtain the high thermal conductivity and suitable electrical insulation. The ceramic coating layer exhibits a porous structure, complete encapsulation and adjustable thickness in the range of 90–600 nm. Employed as the thermal conductive fillers, the SiC-coated MPCF-derived TIMs exhibit comparable thermal conductivity and significantly enhanced electrical insulation performance compared with that from original carbon fiber. For instance, the pad prepared from the coated carbon fiber with a medium coating thickness of 200 nm shows a high through-plane thermal conductivity of 12.8 W m−1 K−1, high electrical resistivity of 3.4 × 1010 Ω cm and satisfactory breakdown voltage value of 1100 V mm−1. This work opens a new avenue to integrate the thermal conductivity and electrical insulation of carbon materials as thermal conductive fillers for electronic packaging.

Recycling of Carbon Fiber-reinforced Epoxy Resin-based Composites Using a Benzyl Alcohol/Alkaline System

High-efficiency recycling of carbon fiber-reinforced epoxy resin-based composites is difficult because of their three-dimensional network structure. In this article, a benzyl alcohol/alkaline system was used to recycle carbon fiber-reinforced epoxy resin-based composites cured by an anhydride. The degradation rate, mechanical properties and degradation mechanism of the recycled carbon fiber were determined by gas chromatography-mass spectrometry, Fourier transform infrared spectroscopy, liquid chromatography-mass spectrometry, scanning electron microscope and X-ray photoelectron spectroscopy. The experimental results indicated that there were two steps in benzyl alcohol/K3PO4 degradation system. The first was transesterification by benzyloxy selective attack to give small-molecule esters. Then the esters were saponified by the alkaline materials. After degradation, the stratification of resin and benzyl alcohol occurred, which was conducive to their separation. The optimal degradation time was 40 min under the weight ratio of alkaline material to benzyl alcohol of 1:10, atmospheric pressure, and temperature of 195 °C and the decomposition efficiency exceeded 90 %. A clean carbon fiber surface was obtained with an oxygen content comparable to that of the original carbon fiber. The tensile strength of the recycled carbon fiber was above 90 % of the original value.

Thin copper hybrid structures by spray-assisted layer by layer chemical deposition on fabric surfaces for electromagnetic interference shielding

In this study, spray-assisted layer by layer chemical deposition was used for the preparation of a thin Cu layer with micro-nano structures on carbon fiber fabrics (CFFs). By adjusting the spraying passes, flocculent layered coarse structures composed of Cu nanoparticles have uniformly been constructed successfully. These copper-coated carbon fiber fabrics (Cu@CFFs) showed excellent electromagnetic interference (EMI) shielding effectiveness (SE), and the total SE of Cu@CFFs-100 was about 20 dB higher than the original carbon fiber fabrics. In addition to the reflection and adsorption effectiveness results, the high SE mainly depends on the outstanding conductivity of the carbon fiber fabric endowed by the deposited nanosized copper and enhanced the reflection loss of the incident electromagnetic wave and the multiple reflections of the internal network structure. Moreover, the stability and multilayer overlay of Cu@CFFs results show the possibility of applying spray-assisted layer by layer chemical deposition to produce EMI shielding materials.

Accelerating the oxidative stabilization of pitch fibers and improving the physical performance of carbon fibers by modifying naphthalene-based mesophase pitch with C9 resin

A spinnable mesophase pitch with 95 vol.% optical anisotropy and 267 °C softening point was prepared through co-polymerization of 95 wt.% naphthalene pitch and 5 wt.% C9 resin. The effects of introducing C9 resin on the formation, structure and properties of naphthalene-derived mesophase pitch and the oxidative stabilization of resulting pitch fibers as well as the final physical properties of carbon fibers were systematically investigated. The results suggest that C9 resin could effectively facilitate the generation and development of liquid crystals in synthetic naphthalene pitch during the heat soaking process and introduce a certain amount of methyl side chains linking in polycyclic aromatic hydrocarbon molecules, so as to reduce the melt viscosity of modified mesophase pitch and improve its flow-spinnability and oxidative reaction capability. The pre-oxidation process of the modified pitch-spun fibers could be completed ahead of 4 h at 240 °C in an air atmosphere, compared with unmodified pitch fibers. This shows a possibility to decrease the production cost of mesophase pitch-based carbon fibers. Although the tensile strength of 1000 °C carbonized fibers prepared from the modified mesophase pitch (1.23 GPa) is slightly higher than that of original carbon fibers (1.18 GPa), the axial electrical resistivity and the thermal conductivity of corresponding graphite fibers after 3000 °C graphitization are 2.0 μΩ m and 677 W/(m K), respectively, which are significantly enhanced in comparison with those of original graphite fibers (3.2 μΩ m and 473 W/(m K).