Carbon Fiber Surface Research Articles

The Influence of Carbon Fiber on Crystallization and Morphology of Poly(Ether Ketone Ketone) Composites Towards High Rate Thermoplastic Manufacturing Processes

Recent interest in thermoplastic composites for aerospace applications is driven by the need for high-volume manufacturing of materials that display excellent mechanical, thermal, and solvent resistive properties. Specifically, a large component of the composite properties of thermoplastic composites are highly dependent on the crystalline fraction of the semi-crystalline polymer matrix of the reinforced system. This work investigates the melting behavior of poly (ether ketone ketone) (PEKK) and the influence of temperature and fiber on crystallization kinetics and morphology of (PEKK) composites utilizing, differential scanning calorimetry, Velaris-Sefaris modelling, and polarized optical microscopy (POM). Annealing temperatures of 380°C and above were required to fully erase crystalline ordering in the PEKK matrix. Furthermore, carbon fibers accelerated crystallization kinetics in PEKK at a range of temperatures observed via DSC, and Velaris-Sefaris modelling implied a shift from bulk to surface induced nucleation by the addition carbon fiber to the PEKK matrix, reducing activation energy of crystallization events. This nucleation behavior was visually confirmed through POM with observation of transcrystalline domains nucleated from the surface of a single carbon fiber.

The Influence of Carbon Fiber on Crystallization and Morphology of Poly(Ether Ketone Ketone) Composites Towards High Rate Thermoplastic Manufacturing Processes

Recent interest in thermoplastic composites for aerospace applications is driven by the need for high-volume manufacturing of materials that display excellent mechanical, thermal, and solvent resistive properties. Specifically, a large component of the composite properties of thermoplastic composites are highly dependent on the crystalline fraction of the semi-crystalline polymer matrix of the reinforced system. This work investigates the melting behavior of poly (ether ketone ketone) (PEKK) and the influence of temperature and fiber on crystallization kinetics and morphology of (PEKK) composites utilizing, differential scanning calorimetry, Velaris-Sefaris modelling, and polarized optical microscopy (POM). Annealing temperatures of 380°C and above were required to fully erase crystalline ordering in the PEKK matrix. Furthermore, carbon fibers accelerated crystallization kinetics in PEKK at a range of temperatures observed via DSC, and Velaris-Sefaris modelling implied a shift from bulk to surface induced nucleation by the addition carbon fiber to the PEKK matrix, reducing activation energy of crystallization events. This nucleation behavior was visually confirmed through POM with observation of transcrystalline domains nucleated from the surface of a single carbon fiber.

A facile method for carbon nanotube/carbon fiber‐reinforced polylactic acid composites

AbstractThe mechanical strength of polylactic acid (PLA) can be improved by carbon fiber (CF) compositing to expand its application in tissue engineering scaffolds. However, the mechanical strength of CF‐reinforced polylactic acid (CFRPLA) composites is compromised due to weak interfacial interaction resulting from the chemically inert surface of CF. In the article, carbon nanotube (CNT) with poly(diallyldimethylammonium chloride) (PDDA) as a coupling agent was covered on CF to improve the chemical activity and roughness of the surface of CF, and then the as‐prepared CF‐PCNT were further incorporated into PLA via melt compounding. The yield strength, modulus, and thermal conductivity of PLA/CF‐PCNT were 14.09%, 7.65%, and 5.24% higher than those of PLA/CF, respectively, and the volume resistivity was 99.74% lower at a 10 wt% loading. The enhancement for the mechanical properties of PLA/CF‐PCNT composites could be ascribed to the mechanical locking, hydrogen bonds and covalent bonds between CF and matrix through the interface modulation of CNT and PDDA. This facile and non‐destructive method offers a novel strategy for the modification of CF fillers.Highlights CF was modified by PDDA and CNT through a facile and non‐destructive method. The active functional groups and roughness on the surface of CF were increased. The surfaces of CFs were characterized by FT‐IR, Raman spectra, XPS and SEM. The interface was improved by mechanical locking, covalent, and hydrogen bonds. The mechanical strength, electrical and thermal conductivity of composites were improved.

Improvement of curing efficiency and heat resistance of CFRP by the growth of SiCNWs on CF

Carbon fiber-reinforced polymer composites are widely used in modern industry. However, poor heat transfer between layers of carbon fiber cloth during the curing process leading to poor curing of the substrate, long curing cycles, and excessive heat accumulation has become an urgent problem to be solved. A common approach is dispersing highly thermally conductive fillers in the polymer matrix to improve the curing efficiency of the composites. Different from adding fillers, we report a novel method of in situ growth of SiC nanowires (SiCNWs) on the surface of carbon fiber (CF) by the chemical vapor deposition (CVD) method and study the effects of CVD deposition time on curing efficiency and thermal stability of the composites. The results indicate that the nano bridge effect of SiCNWs significantly improves the curing efficiency of the composites. Compared with pure CF/epoxy composites, the curing efficiency can be increased by 38.72%. The cross-linking point between SiCNWs and the resin matrix enhances the thermal stability of the composites and increases the heat resistance index ( T HRI) by 8.4°C.

Pearl‐Inspired Colored Carbon Fibers with Electromagnetic Interference and Optical Camouflage Properties

Carbon fibers (CFs) are widely used in cutting‐edge and civilian fields due to their excellent comprehensive properties such as high strength and high modulus, superior corrosion and friction resistances, excellent thermal stability, light weight, and high electrical conductivity. However, their natural ultra‐black appearance is difficult to meet the aesthetic needs of today's civilian sector and the need for optical stealth in the military field. In addition, conventional coloring methods are difficult to effectively adhere to CF surfaces due to high crystallinity and highly inert surface caused by their graphite‐like structure. In this work, inspired by the nacre structural color of pearls, colored CFs with 1D photonic crystal structure are prepared by cyclically depositing amorphous (Al2O3 + TiO2) layers on the surface of carbon CFs through atomic layer deposition (ALD). The obtained CFs exhibit brilliant colors and excellent environmental durability in extreme environments. Moreover, the colored CFs also exhibit high EMI shielding effectiveness (45 dB) and optical stealth properties, which can be used in emerging optical devices and electromagnetic and optical stealth equipment.

Construction of “organic–inorganic” hierarchical structure of carbon fibers and the effect on the properties of epoxy composites

AbstractThe demand for epoxy (EP) in semiconductor, aerospace, and other applications is currently on the rise. However, pure epoxy is difficult to meet these requirements, such as low thermal conductivity and poor toughness. Therefore, in this paper, sulfonamides (SAs) and core‐shell silica (SLC‐SiO2) were grafted onto the surface of short carbon fibers (SCF) with sizes of 0.1–6 mm by the chemical grafting method. As a result, the surface activity of SCF was improved and the interfacial properties of the EP composites were enhanced. The interfacial compatibility of SCF grafted with SAs and SLC‐SiO2 in EP is greatly improved, resulting in stronger mechanical interlocking and chemical bonding ability between EP and SCF. The results showed that when the content of SCF@SAs@SLC‐SiO2/EP composites reached 0.3 wt% of SCF@SAs@SLC‐SiO2, the impact and tensile strengths were increased from 12.15 kJ·m−2 and 43.4 MPa to 16.93 kJ·m−2 and 74.97 MPa compared with the pure epoxy, which were improved 39.3% and 72.7%. In addition, the thermal conductivity of SCF@SAs@SLC‐SiO2/EP composites was also improved by 12.5% from 0.205 W·(m·K)−1 to 0.2306 W·(m·K)−1 compared with the pure EP. This is due to improved chemical interactions and mechanical interlocking at the fiber‐epoxy interface. This study provides a new method for the preparation of high‐performance SCF/EP composites.Highlights The amino group of sulfonamides was grafted with short carbon fiber to increase the surface active group of short carbon fiber. Sulfonamides react with carboxyl groups on the surface of core‐shell silica to form an “organic–inorganic” structure. Improve the surface roughness of short carbon fiber, and make it evenly dispersed in epoxy resin, so as to improve the performance of epoxy composite materials.

Density Functional Theory Study of Adhesion Mechanism between Epoxy Resins Cured with 4,4'-Diaminodiphenyl Sulfone and 4,4'-Diaminodiphenylmethane and Carboxyl Functionalized Carbon Fiber.

The molecular mechanism of adhesion of two epoxy resins based on diglycidylether of bisphenol A (DGEBA) cured with 4,4'-diaminodiphenyl sulfone (DDS) and 4,4'-diaminodiphenylmethane (DDM) to the carbon fiber (CF) surface is investigated by employing density functional theory (DFT) calculations. The CF surface was modeled by the armchair-edge structure of graphite functionalized with carboxyl (COOH) groups. Two adhesion interfaces were constructed using the CF surface: one with the DGEBA-DDS molecule (CF/DGEBA-DDS interface) and the other with the DGEBA-DDM molecule (CF/DGEBA-DDM interface). The interfacial properties were analyzed by calculating the maximum adhesion stress (Smax) at the interface. The adhesion stress-displacement curve revealed that Smax is 1160.37 MPa, higher for the CF/DGEBA-DDS interface compared to the CF/DGEBA-DDM interface, which is 1060.48 MPa. The energy decomposition analysis showed a similar DFT contribution to adhesion stress for both interfaces, but the dispersion contribution is more significant at the CF/DGEBA-DDS interface. The crystal orbital Hamilton population (COHP) analysis revealed distinct interfacial interactions despite similar DFT contributions. Hydrogen bonding (H-bonding) between the functional groups at both interfaces including feeble OH-π interactions between the benzene rings of epoxy resins and COOH groups on the CF surface were observed. The orbital interaction energies calculated from integrated COHP, i.e., IpCOHP, revealed that the CF/DGEBA-DDS interface has six H-bonding interactions with large absolute IpCOHP values (>1 eV), whereas the CF/DGEBA-DDM interface has five. The interaction between the amine group of the DGEBA-DDM molecule and the CF surface has a large IpCOHP value among all interactions. The sulfone group being at the center of the DDS molecule and its strong surface interaction positioned the DGEBA-DDS molecule closer to the CF surface than the DGEBA-DDM molecule, enhancing dispersion interaction at the CF/DGEBA-DDS interface. Hence, the CF surface exhibits a stronger affinity toward the DGEBA-DDS molecule than the DGEBA-DDM molecule through dispersion interaction.

Indium Nanoparticle‐Decorated Graphite Felt Electrodes for Efficient and Long‐Cycle Zinc‐Bromine Flow Batteries

AbstractZinc‐bromine flow batteries (ZBFBs) offer the potential for large‐scale, low‐cost energy storage; however, zinc dendrite formation on the electrodes presents challenges such as short‐circuiting and diminished performance. Herein, an indium nanoparticle‐decorated graphite felt composite electrode for ZBFBs is proposed to mitigate zinc dendrite formation, improve performance, and prolong operational longevity. Using a facile in situ electrodeposition method, indium nanoparticles are uniformly and densely distributed on the carbon fiber surface, demonstrating exceptional efficacy in regulating zinc deposition. Thus, a higher prevalence of Zn (002) crystal planes and a smoother and more compact surface morphology are obtained, compared with those of thermally treated graphite felt. Furthermore, integration of the composite electrode into the negative side of a ZBFB yielded substantial improvements in cell performance, achieving an energy efficiency of 66.83% ± 0.45% at 120 mA cm−2, significantly surpassing the performance of batteries utilizing thermally treated graphite felt (52.64% ± 1.50%). Notably, the cycle life of the battery is extended by more than five‐fold with the composite electrode, underscoring the remarkable zinc deposition‐regulating capabilities of the indium nanoparticles.

Flexible supercapacitors based on in-situ synthesis of composite nickel manganite@reduced graphene oxide nanosheets cathode: An integration of high mechanical flexibility and energy storage

Supercapacitors have attracted considerable attention in the context of electric vehicles, renewable energy storage, and industrial equipment. Nevertheless, further work is required to enhance the energy storage performance and improve the adaptability of supercapacitors under mechanical loads. To address these challenges, we propose a novel design strategy for composite micro-nano structures of reduced graphene oxide coated in situ growth of nickel manganite nanoarrays on the carbon fiber surface (CF@NiMn2O4@rGO). This design enables the fabrication of flexible supercapacitor electrodes with optimised electrochemical and mechanical properties. The CF@NiMn2O4@rGO cathode exhibits a synergistic effect that enhances energy storage, as evidenced by a high specific capacitance of 1003.35 F g−1 (at 10 mA cm−2) and exceptional cycling stability over more than 4000 cycles. Furthermore, the flexible carbon fiber (CF) and in-situ grown nickel manganite@reduced graphene oxide (NiMn2O4@rGO) contribute to improved mechanical properties of the electrode. The assembled supercapacitor exhibits both high energy density and cycling stability. Notably, the flexible bending angle ranging from 0° to 180° has minimal impact on the energy storage performance of this flexible supercapacitor. Even under a bending angle of 180°, it successfully powers a small light bulb. This novel nanostructured material presents an innovative approach for designing flexible supercapacitors.

A “sizing-free” strategy to improve the interfacial property of PEEK/CF composites based on “grafting-bridging” bifunctional diazonium salt

Achieving simple and efficient interfacial modification between carbon fiber and polyether ether ketone (PEEK) has been the pursuit of researchers. In this study, by comparing the nucleophilicity of various aromatic amines, a direct Schiff base reaction with polyether ether ketone (PEEK) has been achieved. Based on this, a “grafting-bridging” bifunctional diazonium salt containing a phenylethylamine structure was designed and synthesized to enhance the interfacial strength through covalent bonding without the use of sizing agents. The diazonium salt was grafted onto the surface of carbon fiber through electrochemical reduction, while the PEEK resin and phenylethylamine could achieve bridging through heat treatment, thus a PEEK/CF interface with enhanced covalent bonds was constructed. The reaction and conversion rate between phenylethylamine and PEEK resin were confirmed through IR and NMR. The successful grafting of the diazonium salt on the carbon fiber was determined through XPS and cyclic voltammetry. The bridging reaction on the surface of carbon fiber was verified through XPS and the use of 6F-PEEK with characteristic elements. As a result, the interfacial shear strength (IFSS) of the modified PEEK/CF interface reached 86.2 MPa, representing a 102.8 % improvement compared to the untreated interface of 42.5 MPa, fully demonstrating the excellent effect of the bifunctional diazonium salt.

Polydopamine modified carbon fiber to improve the comprehensive properties of carbon paper for proton exchange membrane fuel cell

In this study, polydopamine (PDA) was used to modify functional groups on the surface of carbon fiber (CF), and the effects of different dopamine hydrochloride (DPH) concentrations on the surface morphology, functional groups, contact angle and dispersion stability of CF were studied. Subsequently, the raw carbon paper (RCP), hot-pressed carbon paper (HPCP) and carbon paper (CP) were prepared successively using the modified CF through wet forming, impregnation/hot-pressing, and carbonization methods. The surface morphology, tensile strength, flexural strength, electrical resistivity, air permeability and pore size distribution were analyzed for these materials. It was observed that the introduction of −OH and − NH2 groups improved the hydrophilicity and dispersion of PDA modified CFs, resulting in an increase in formation index (FI) from 39.2 to 48.1 for RCP samples. With increasing DPH concentration, the tensile strength of CP initially increased but then decreased while its electrical resistivity showed an opposite trend. Finally, PDA modified CP was assembled into proton exchange membrane fuel cells (PEMFC). The PEMFC assembled from DPH-CP-2.5 achieved a maximum limiting current density of 1440.0 mA/cm2 and power density of 458.25 mW/cm2. Meanwhile, the lower material transmission impedance for DPH-CP-2.5 as well as excellent water management ability and gas transmission performance.

Enhancing interfacial locking of the CF and PBPESK resin by in-situ electrochemical deposition of MOF nanoparticles

The interfacial bonding of carbon fiber reinforced polymer composites plays a critical role in the overall performance of the composites. Poor interfacial bonding leads to catastrophic damage of composites when subjected to external loads. In this study, three-dimensional (3D) NH2-UiO-66 nanoparticles in-situ synthesis on the carbon fiber (CF) surface using an electrochemical method was achieved facilely and efficiently to enhance the interfacial adhesion of CF/PBPESK composites. The influence of incorporating 3D NH2-UiO-66 nanoparticles into the interphase on the interfacial and mechanical properties of carbon fiber reinforced composites was systematically investigated. The NH2-UiO-66 nanoparticles significantly increased the carbon fibers surface energy. The flexural, interlaminar shear and interfacial shear strength of the N–CF–6min/PBPESK composite were improved by 19 %, 31 %, and 93 %, respectively, compared to the D-CF/PBPESK composite. Furthermore, the interfacial failure mechanism of the composites was investigated. This approach offered a simple and efficient strategy for the in-situ synthesis of interfacial phase characterized by robust mechanical locking effects.

Impact of graphene oxide lateral sizes on the mechanical and thermal properties of carbon fiber composites

AbstractThe impact of carbon fiber (CF) composites sizing with graphene oxide (GO) to form brick‐and‐mortar structures on their mechanical properties and thermal conductivity has not been closely examined. This study systematically investigates the effect of GO sheet size on the interfacial properties and thermal conductivity of CF composites. Three sizes of GO—small (0.11 μm), medium (0.33 μm), and large (0.97 μm)—were used to modify CF surfaces via layer‐by‐layer self‐assembly, forming the brick‐and‐mortar structures. The mechanical properties were assessed through flexural tests, interlaminar shear strength (ILSS) tests and tensile tests, while thermal conductivity was measured using a thermal constant analyzer. The results revealed that medium‐sized GO (GO‐M) significantly enhanced the interfacial strength and toughness of the composites. This improvement is attributed to the orderly arrangement of GO‐M on the CF surface, which enhances stress transfer between the fiber and the matrix. In contrast, small‐sized GO (GO‐S) tended to scatter, resulting in less effective reinforcement, while large‐sized GO (GO‐L) exhibited stacking and agglomeration, limiting its reinforcement effectiveness. However, GO‐L provided the highest thermal conductivity due to the formation of continuous heat conduction pathways. These findings suggest that GO‐M offers a balanced improvement in mechanical properties, whereas GO‐L is more suitable for applications requiring high thermal conductivity. This work underscores the importance of selecting the appropriate GO sheet size to optimize the interfacial properties and thermal conductivity of CF composites, which is crucial for enhancing their performance in high‐end engineering applications, such as aerospace, automotive, and marine industries.Highlights Modification of CF composites by GO‐M sheets significantly improved toughness and strength. GO‐L sheets formed an effective heat transfer channel with the highest thermal conductivity. The study emphasized the critical role of selecting the appropriate GO sheet size to optimize the mechanical and thermal properties of CF composites.

Surface modification of carbon fibres via plasma-activated water for mitigating burnout risk from direct plasma treatment

This study presents a novel plasma jet discharge device designed to indirectly treat carbon fibre materials with plasma-activated water. This innovative method effectively mitigates issues related to carbon fibre conduction and combustion, which are common challenges encountered when directly modifying fibres using a plasma jet. Specifically, the atmospheric composition is adjusted to modulate the active particles in the liquid phase. The experimental results demonstrate that this technique significantly increases the surface wettability of carbon fibres without damaging their structure. Under the conditions of argon/oxygen cascade discharge, oxygen-containing substances generate ionomers that activate the water, which in turn introduces oxygen-containing groups (e.g., C−O, C=O, O−C=O) onto the carbon fibre surface. These groups catalyse monomer polymerisation on the material surface, which increases the wettability of the carbon fibres, as evidenced by a significant reduction in the water contact angle from 80.12° to 55.31°. This in turn improves the bonding strength with epoxy resin and slightly increases the monofilament strength. Furthermore, composites produced by this method exhibit 21% higher interlaminar shear strength than the untreated sample and an increased O/C ratio of up to 24.55%. In summary, these findings provide a valuable theoretical basis for enhancing the surface properties of carbon fibre composites through plasma–liquid interactions and open new possibilities for high-performance carbon fibre–resin matrix composites.

In situ growth of graphene on carbon fibers to enhance the mechanical and thermal conductivity of epoxy composites

High-strength and high-thermal-conductivity composite materials have become crucial requirements for thermal control systems in various field. Carbon fiber-reinforced polymer (CFRP) has demonstrated potential superior performance. However, the application of CFRP is limited by the chemical inertness of the carbon fiber surface and the shortness of low surface energy. Therefore, surface modification of carbon fibers is necessary. This research employs a pulse plasma discharge method, to in-situ grow graphene on the surface of carbon fibers by disrupting some polymer structures on the carbon fiber surface in a “bottom-up” approach. This method offers advantages such as rapid, simple, convenient, economical, and environmentally friendly preparation process., the modified carbon fibers used in CFRP exhibit superior mechanical and thermal conductivity properties. The flexural strength increased by 218 % to reach 109.5 MPa, and the thermal conductivity increased by 251 % to achieve 1.153 W/(m*K).

Synchronously Repairing Core/Surface Defects of Carbon Fibers by In Situ Growth of ZIF-8 and Uniquely Matched High-Energy Irradiation.

Currently, the actual mechanical properties of carbon fibers (CF) differ significantly from the theoretical values. This is primarily attributed to significant limitations imposed by structural defects, greatly hindering the widespread application of CF. To solve this problem, we used in situ growth of zeolitic imidazolate framework-8 (ZIF-8) and γ rays to modulate the core-shell of CF in this study. For the surface structure of CF during the process of γ irradiation, the organic structure within ZIF-8 gradually degrades and forms a cross-linking structure with the surface defects of the CF. This process significantly enhances the binding strength between inorganic material from the postdecomposition of ZIF-8 and the carbon layer on the surface of CF, repairing the surface defects. For the internal structure of CF, γ irradiation can improve the orientation of the internal micropores of CF and increase the degree of internal graphitization of CF. In this paper, an in-depth analysis of CF before and after repair was conducted by using characterization techniques such as nanoindentation and ultrasmall angle X-ray scattering (USAXS). Compared to unmodified CF, its mechanical properties improved by approximately 19.99%, which exceeds that in approximately 95% of similar works in the field.

Improved interfacial properties of carbon fiber reinforced epoxy resin composite by in‐situ self‐assembled mental‐phenolic networks

AbstractThe chemical modification of carbon fiber surface often uses toxic reagents and harsh reaction conditions, while the preparation process of metal‐phenol networks (MPNs) is simple, rapid, non‐toxic and harmless, which provides a direction for alleviating environmental problems. In this study, tannic acid (TA) was coordinated with Fe3+ to form MPNs, which was coated on the surface of carbon fibers through π‐π interaction. The results indicated that oxygen functionalities on the surface of the MPN coating can facilitate better adhesion between the carbon fiber and the epoxy resin, when the molar ratio of TA to Fe3+ is 1:3 and the pH is 4, the interlaminar shear strength (ILSS) performance of the composite material reaches its optimal level. In addition, a green and non‐destructive method is provided for the surface modification of carbon fiber, which can effectively optimize the interfacial properties of carbon fiber reinforced polymer (CFRP) composites.

High-performance composite electrode based on polyaniline/graphene oxide carbon network for vanadium redox flow batteries

In this study, an electrode wrapped in a carbon network is fabricated using a straightforward hydrothermal technique. Conducting polymers such as polyaniline (PANi) have been used to form carbon networks on the surfaces of carbon fibers. However, the cycling instability of PANi, which is a consequence of structural modifications, is a significant obstacle to its commercial application. This study presents an innovative and effective approach for synthesizing carbon networks using PANi/reduced graphene oxide (PANi-rGO-CF) composites to enhance the performance of vanadium redox flow battery (VRFB) electrodes. PANi-rGO was deposited on carbon felt using a hydrothermal method, followed by calcination under an argon atmosphere. The presence of graphene oxide facilitated the uniform distribution of PANi and enhanced its stability. PANi-rGO-CF demonstrated superior electrocatalysis toward vanadium redox couples owing to the abundant heteroatom active sites, affording VRFBs with extraordinary stability and outstanding energy efficiency after 100 cycles at 100 mA/cm2.

Microstructure and properties of Al/FeCoNiCrMo coatings prepared by different plasma spraying currents on carbon fiber reinforced plastic surfaces

Al/FeCoNiCrMo high-entropy alloy (HEA) coatings were prepared on the surface of carbon fiber reinforced plastic using plasma spraying technology. The microstructure of the HEA coatings was characterized under different spraying currents, and the hardness, interfacial bonding, corrosion resistance and friction and wear properties of the coatings were tested. The results showed that with the increase of the current, the unfused particles in the coatings decreased, and the coating porosity and thickness also decreased gradually; the hardness, corrosion resistance and friction and wear resistance properties increased with the increase of the current, in which the maximum hardness was 740.3 HV0.1, and the minimum self-corrosion current was 1.21 × 10−5 A·cm−2, and the minimum volumetric wear rate was 7.66 × 10−5 mm3·N−1·m−1.

Modulating Carbon Fiber Surfaces with Vinyltriethoxysilane Grafting to Enhance Interface Properties of Carbon Fiber/Norbornene-Polyimide Composites.

In this study, vinyltriethoxysilane (TEVS) was introduced onto the surface of carbon fiber using liquid-phase oxidation and impregnation methods to incorporate vinyl groups onto the carbon fiber, thereby enhancing the chemical bonding between the carbon fiber and norbornene-polyimide (PI-NA). Through a systematic study of the hydrolysis conditions and concentration of the TEVS solution, the optimal modification conditions were determined. These conditions were used to graft TEVS onto the surface of oxidized carbon fiber to prepare carbon-fiber-reinforced PI-NA composites (CF/PI-NA). The results show that when carbon fiber was treated with a 0.4 wt% TEVS solution, the interlaminar shear strength (ILSS) of the composites reached 65.12 MPa, and the interfacial shear strength (IFSS) reached 88.58 MPa, representing increases of 27.58% and 35.62%, respectively, compared to the CF/PI-NA composite materials prepared from untreated carbon fiber. It is worth noting that the modification method described in the study is simple and easy to implement, and it has the potential for large-scale continuous production applications.