Surface Modification Of Carbon Fiber Research Articles

Mechanical improvement of carbon fiber/epoxy composites by sizing functionalized carbon nanotubes on fibers

AbstractA sizing agent mainly consisting of polyethersulfone and acidified multi‐walled carbon nanotubes (MWCNT) was developed for surface modification of carbon fibers (CF) to enhance the interfacial bond and to form carbon fiber‐carbon nanotube (CF‐MWCNT) multiscale reinforcements. To prepare the modified carbon fiber/epoxy resin composites (CFRP), a vacuum molding technique was used in this study. The effects of the MWCNT‐containing sizing agent on the morphology and chemical structure of the CF surface were observed by scanning electron microscopy and Fourier transform infrared spectroscopy. The influence of MWCNT length and content on the mechanical properties of CFRP were also studied. The experimental results showed that the strength of the CFRP decreased with the increase of MWCNT length, and the MWCNT with a content of 0.05 wt% had a good reinforced effect on the CFRP. After the sizing treatment, the interlaminar shear strength (ILSS) of the CFRP is increased. These enhancements are attributed to the improved mechanical bonding and chemical bonding between CF and resin matrix. The MWCNT provides nanosized rough surface to CF and these acidified MWCNTs attached to the surface of CF with polar oxygen‐containing functional groups improve the compatibility with reinforcement and resin matrix.Highlights Carbon fiber was modified by a sizing agent mainly consisting of polyethersulfone and acidified carbon nanotube (CNT). CNTs enhance the interfacial chemical bonding and mechanical bonding. The CNT length affects the mechanical properties of the carbon fiber/epoxy resin composites (CFRP). The modified carbon fiber has enhanced the mechanical properties of the CFRP.

Fabrication of GNPs sprayed carbon fiber and its effects on the interfacial and mechanical behavior of reinforced epoxy multiscale laminated composite

AbstractThe current research compares the effects of modifying carbon fiber [via spraying graphene nanoplates (GNPs)] and/or GNPs reinforcement on the mechanical and interfacial behavior of carbon fiber epoxy composites. Using a spraying method, the epoxy matrix was reinforced, and carbon fiber was modified with 0.2 and 1 wt% of GNPs, respectively. Tensile, interlaminar, and dynamic mechanical analyses (DMA) tests were conducted on the composite to assess the role of GNPs in enhancing mechanical, interfacial, and thermomechanical properties. The obtained results indicate that the spraying technique effectively enhanced the ultimate tensile strength (UTS) and interlaminar fracture toughness (ILFT) of the composite. The UTS improved by 31%, while the ILFT significantly improved by 38%. Additionally, assessing the modulus gradient through the interface shows improved interfacial interaction between modified carbon fiber and reinforced epoxy. Scanning electron microscopy examination of the fractured surfaces indicated that the existence of nanofillers with high surface area contributed to significant improvements in adhesion between the modified fiber and reinforced epoxy matrix, leading to enhanced interfacial, mechanical, and thermomechanical properties of CFRPs for structural applications.Highlights Incorporation of surface modified carbon fibers and GNPs reinforcement in the epoxy matrix to enhance the interfacial interaction. Evaluation of the effects of GNP nanofiller on interfacial and mechanical performance of the composite. Fracture surfaces in ILSS, tensile, and mode I test were analyzed using FESEM. Utilization of nanoscale modulus mapping for the fiber‐matrix interface assessment.

Influence of Interfacial Interaction and Composition on Fracture Toughness and Impact Properties of Carbon Fiber-Reinforced Polyethersulfone.

In this study, the interlaminar fracture toughness and impact strength of polyethersulfone reinforced with continuous carbon fibers were studied. Interlaminar fracture toughness tests were performed using the double cantilever beam method. It was shown that surface modification using the thermal oxidation method of the carbon fibers can strongly increase the interlaminar fracture toughness of the obtained composites. Thus, the maximum value reached 1.72 kJ/m2, which was 40% higher than the fracture toughness of the composites reinforced with initial carbon fibers. Moreover, fractographic analysis using a scanning electron microscope allowed us to highlight the main reasons for the dependence of fracture toughness on fiber content and surface modification conditions of the carbon fibers. It was shown that the main factor that allowed for an increase in fracture toughness was the enhanced interfacial interaction between the fibers and polymer matrix. Additionally, it was found that expectedly, there was a good correlation between interlaminar fracture toughness and interlaminar shear strength results. However, a negative influence of surface modification on the impact properties of composites was found. Such behavior occurred because of higher structural stability and lower exposure to delamination in multiple layers of the composites reinforced with the modified carbon fibers. It was found that impact energy reached ~150 kJ/m2 for the polyethersulfone-based composites reinforced with initial fibers, while the composites reinforced with modified carbon fibers showed impact energy values of only ~80 kJ/m2. Nevertheless, surface modification of carbon fibers using the thermal oxidation method can be an effective method for improving the performance properties of polyethersulfone-based composite materials.

Decoration with electronegative 2D materials based on chemical transition layers on CFR-PEEK implants for promoting osteogenesis

Due to the unique lamellar structures, physicochemical and biological properties, electronegative two-dimensional (2D) materials have been explored for surface modification of carbon fibers reinforced polyetheretherketone (CFR-PEEK) composite. Deposition of electronegative 2D materials based on a porous surface created by concentrated H2SO4 has been studied to promote osteogenesis of CFR-PEEK. Generally, a porous layer will be pre-built on CFR-PEEK through severe corrosion of concentrated sulfuric acid to help the loading of 2D materials. However, the severe corrosion will greatly reduce surface mechanical strength, especially wear resistance and hardness, which increases the risk of collapse or even peeling of the bioactive coating by external force. Herein, instead of the severe corrosion, a mild corrosion by concentrated HNO3 was applied to modify the surface of CFR-PEEK to pre-create a dense transition layer for the further surface decoration of electronegative 2D materials (graphene oxide (GO) and black phosphorus (BP), representatively). The results indicated that hardness and wear resistance of the dense transition layer were markedly higher than those of the porous layer. Although GO and BP can be both loaded on these two transition layers, –SO3H on the porous transition layer showed moderate cytotoxicity, while –NO2 on the dense transition layer showed good cytocompatibility. The dense transition layer displayed higher mineralized deposition in vitro and new bone formation rate in vivo than the porous transition layer, moreover, GO and BP coatings improved osteogenesis. This work offers inspirations for the construction of electronegative 2D material coating on CFR-PEEK based on chemical transition layers.

Aging Effect of Plasma-Treated Carbon Fiber Surface: From an Engineering Point

Dielectric barrier discharge (DBD) plasma surface modification has certain aging effect. This article studies the aging effect of plasma (DBD) on the surface modification of carbon fibers. The test results show that plasma (DBD) treatment reduces the impurity particles on the surface of carbon fibers and makes the surface texture coarser. In addition, there is no significant change. After plasma (DBD) treatment, the content of C–O–C, C–O and C=O on the surface of carbon fibers increased from 3.20%, 7.76% and 1.64% to 7.06%, 21.50 and 6.08%, respectively. This is due to the high-energy particle bombardment of the fiber surface, which forms activated carbon atoms on the surface. The free electrons of these activated carbon atoms combine with ionized oxygen in the air. However, with the passage of time, the content of C–O–C, C–O and C=O gradually decreases to 3.31%, 8.57% and 1.77%, respectively. This is because some functional groups formed on the treated carbon fiber surface are not firmly bound, and some of these functional groups containing O2 groups will combine with surrounding substances through irreversible chemical oxidation reactions to produce CO2, which leaves the carbon fiber surface as a gas. The treated carbon fibers will immediately become hydrophilic, and the water contact angle decreases from 148.71° to 0°. With the passage of time, the water contact angle gradually increases to 118.16°, and the hydrophobicity recovers.

Research progress on the surface modification of carbon fiber.

Carbon fiber (CF) has high strength, high modulus, and excellent high-temperature resistance and chemical stability; therefore, it is used in diverse fields. However, due to the lack of active functional groups on the surface of CF and surface defects generated during the preparation of CF, the wettability of the fiber surface is poor, which seriously affects the interface performance between the fiber and a resin matrix. In recent years, extensive research has been conducted on the surface modification of CF. In this review, studies on the surface modification of CF are summarized, including the various methods utilized, such as dry modification, wet modification, and nanomodification, as well as their current application status. As interest in this material increases, high-performance CFs will likely play an important role in many fields in the future.

Surface modification of carbon fibers for enhanced electromagnetic absorption

The exceptional chemical and physical properties of carbon fiber make it highly promising for utilization in the field of wave-absorbing materials. However, the low magnetic loss and high complex permittivity of conventional carbon fiber materials limit their use in wave-absorbing materials. Hence, this study presents the synthesis of a FeCoNi/N-doped carbon coating/SCF composite with a distinctive microstructure by an in-situ reduction process. The successful formation of this unique architecture was confirmed through various characterization techniques. The composite material displayed both magnetic and dielectric characteristics. It showed an effective bandwidth spanning 14.77 GHz with a reflection loss (RL) of − 10 dB or less. In addition, it attained the minimum RL value of − 50.5 dB at a distance of 3.5 mm. The composite material is hypothesized to show great potential in electromagnetic wave absorption.

3-isocyanatopropyltriethoxysilane block-graft engineering tailoring carbon fiber surface to manipulate interface properties of carbon fiber/polyamide 6 composites

Introducing the isocyanate group on carbon fiber (CF) to improve its surface activity is an effective method for CF surface modification. However, its application in industry is limited by the fact that the modification process is harmful to the environment and the isocyanate is prone to fail. In this paper, caprolactam (CPL) was used to block the isocyanate bond of 3-isocyanopropyltriethoxysilane (IPTS). By adjusting the hydrolysis conditions and concentration of the modified coupling agent solution, the CPL-blocked IPTS was grafted onto the surface-oxidized CF, and the CF-reinforced polyamide 6 (PA6) composites were prepared. The results showed that the interlaminar shear strength (ILSS) of the composites reached 52.53 MPa after treating CF with 1.0 wt% of coupling agent solution, which was 23.83% higher than that of the desized CF/PA6 composites. During the composite molding process, the high temperature unblocked the IPTS, and the released isocyanate reacted with the terminal amino group of PA6 by covalent grafting to establish a high-strength composite interface, which was the main reason for the improvement of ILSS. This study shows that this method is simple and environmentally friendly, and can effectively improve the interface properties of CF/PA6 composites.

Modification of Carbon Fiber Surface under Plasma Ion Irradiation with Energies from Hundreds of eV to Tens of keV

Modification of Carbon Fiber Surface under Plasma Ion Irradiation with Energies from Hundreds of eV to Tens of keV

Enhancing mechanical properties and thermal conductivity in polymer bonded explosives by multi-scale surface modification of carbon fibers

Poor interfacial interaction and strength largely restrict the overall performance and practical application of carbon fibers (CFs) reinforced composites. The favorable interfacial properties were the key to realize superior mechanical properties in composites. Herein, we reported a novel multi-scale surface modification strategy of CFs to strengthen interfacial properties. Based on chemical oxidation treatment, the surface of CFs was further in situ grafted by a crosslinked high-strength polymer network consisting of aromatic diisocyanate, graphene oxide (GO) and polyethylenen glycol (PEG), which significantly improved the interfacial bonding and mechanical strength of interface layer itself. Benefitting from this multi-scale surface treatment, a high-efficiency mechanical enhancement of polymer bonded explosives (PBX) was achieved. With only 0.3 wt% fiber content, the maximum tensile and compressive strength PBX composites were both significantly improved, which were 63 % and 39 % higher than those of pure PBX, respectively. Meanwhile, the thermal conductivity was also enhanced, yielding a significant synergistic enhancement effect. The interface failure mechanism of the composite under stress was clarified by the fracture morphology characterization. This study sheds a light for exploring novel surface modification and has the potential application in in high performance polymer composites.

Solvent-free surface modification of milled carbon fiber using resonant acoustic mixing

Resonant Acoustic Mixing (RAM) is used to rapidly modify the surface of milled carbon fiber using diazonium salts in solvent free conditions. This novel method allows tuning of the surface properties of this material and reduces the environmental footprint usually associated with surface modification of carbon fiber (discontinuous or otherwise). As a proof of concept, fluorine-containing diazonium salts were successfully grafted as determined by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and an increase in water contact angle (WCA) of the milled carbon fiber samples (+15°). Atomic Force Microscopy (AFM) together with SEM revealed the surface structure and integrity of the milled carbon fibers could be maintained despite vigorous mixing conditions. Using RAM proved more efficient than positive controls produced under thermal conditions in solvent.

Surface modification of carbon fiber by vinyl functionalized silane to enhance the interfacial adhesion with rubber via co-vulcanization

The application of carbon fiber reinforced rubber composites was restricted by the poor interfacial combination. To construct an effective interfacial transition layer, vinyl polysiloxane was introduced to be a chemical bridge connecting carbon fiber and rubber in this study. A modification method was designed since silicon hydroxyl generated from hydrolysis vinyl siloxane could be connected with carbon fiber through ether bond while unsaturated vinyl groups could be used as crosslinking point to form interpenetrating network by following vulcanization. This mechanism was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy characterization for the surface of carbon fiber during modification. The immigration of sulfur from rubber matrix to the established interfacial layer was also verified by the distribution of sulfur element based on scanning electron microscopy-energy dispersive spectroscopy results. The contact angle and H-shape pull-out test was applied to evaluate the surficial activity of carbon fiber and the interfacial properties of carbon fiber reinforced rubber composites. The results showed that the interfacial performance was improved significantly since the H-shape pull-out force of modified carbon fiber reinforced rubber, which means the strength of the interfacial layer, could be more than 3 times as that of untreated samples.

The hierarchical layer with dynamic imine bonds on carbon fiber surface to simultaneously improve interface and electromagnetic shielding properties of carbon fiber reinforced thermoplastic composites

Constructing surface hierarchical layer is regarded as an effective surface modification of carbon fibers (CFs) to enhance their composites mechanical properties. However, this method usually deteriorates the intrinsic properties of CF and the hierarchical layer is not fully compatible with thermal processing of the polymer. Here, a novel hierarchical layer consisting of polydopamine, polyethyleneimine and multi-walled carbon nanotubes without damages to CF was successfully decorated on CF surface (CNT@PP-CF) for simultaneously enhancing the mechanical and the electromagnetic interference (EMI) shielding properties of CF reinforced polyamide 66 (PA66) composite. The CNT@PP hierarchical layer with dynamic imine bonds enhanced the interfacial wettability and bonding between CF and PA66 during thermal processing. Compared with that of untreated-CF, the interfacial shear strength and tensile strength of CNT@PP-CF/PA66 composite were increased by 52.3% and 19.2%, respectively. Meanwhile, the EMI shielding performance was enhanced by 89.6%. This improvement would be ascribed to the dynamic imine polar groups and heterogeneous interfaces in the hierarchical layers which enhanced the conductive and dielectric losses of composites. Our research provided a novel approach based on dynamic covalent bond exchanges to achieve the functional and structural integration of CF reinforced thermoplastic resin composites.

Self-assembly of carbon nanomaterials onto carbon fiber to improve the interfacial properties of epoxy composites

The interfacial property of carbon fiber (CF) reinforced composites is crucial to facilitate the application of high-strength composites. Utilizing the electrostatic and hydrogen bond properties of diazo resin, carbon nanotubes (CNTs) and graphene oxide (GO) could be quickly grafted onto the surface of the CF via the layer-by-layer self-assembly technique. The results showed that CNTs and GO were uniformly coated onto the CF surface, and the chemical activity and roughness of the modified CF surface were improved significantly. The modified CF surface can significantly augment the interaction between the epoxy resin and the fiber. Remarkably, due to the good interfacial property, the impact performance of the composites reinforced with the nanomaterial-modified CF was improved obviously. In addition, the interface properties of the composites are studied in depth. This method is expected to achieve rapid surface modification of carbon fiber.

Ion-Beam Surface Modification of Carbon Fibers

Ion-Beam Surface Modification of Carbon Fibers

Ion-Beam Surface Modification of Carbon Fibers

Ion-Beam Surface Modification of Carbon Fibers

Carbon fiber surface modification by ion implantation for interfacial performances improvements of epoxy composites

Carbon fiber surface modification by ion implantation for interfacial performances improvements of epoxy composites

Simultaneously reducing the modulus difference and smoothing the modulus transition through bi-directional structural design for enhancing interfacial properties of carbon fiber/epoxy composites

The modulus mismatch between CF and resin and the weak interfacial bonding strength result in poor interfacial properties, limiting its application in the field of structural materials. In this study, the modulus difference reduction and the gentle modulus transition would be achieved by simultaneously designing structures of the carbon fiber (CF) and resin to enhance the interfacial properties of the composite. The modulus difference was narrowed by improving resin modulus. Meanwhile, the multi-scale structural design on CF surface smoothed the transition modulus from fibers to resin. In brief, under the above combined effects, a multi-stage modulus gradient decreasing structure was constructed, which could make the external stress more effectively dispersed for excellent interface properties. The bi-directional structural design increased the ILSS of CF/EP composites to 82.6 MPa, which was 17.7% and 8.0% higher than that of CF surface modification only and EP modification only, respectively. This work was expected to provide new ideas for improving the mechanical properties of CF composite through multi-scale structural design to meet the needs of different fields.

Graphite oxide/reduced graphite oxide surface modified carbon fiber reinforced composites for deicing and electromagnetic interference shielding

Graphite oxide/reduced graphite oxide surface modified carbon fiber reinforced composites for deicing and electromagnetic interference shielding

Effect of surface modification of carbon fiber based on magnetron sputtering technology on tensile properties

In this study, carbon films were constructed on the surface of carbon fibers using magnetron sputtering to improve the surface defects and mechanical properties of carbon fibers. The tensile properties of the single carbon fiber and multifilament carbon fiber before and after modification were tested, and the influence of the modification method on the tensile properties of the carbon fiber was analyzed. Moreover, the effect of the modification process on the dispersion of the tensile breaking strength of the carbon fiber was analyzed using the Weibull distribution. The magnetron sputtering process based on a carbon target successfully repaired the surface and improved the dispersion of the tensile breaking strength of the carbon fiber. After surface modification, the CV value of the breaking strength of the single carbon fiber and multifilament carbon fiber decreased by up to 57.5% and 31%, respectively. The Weibull modulus m of the modified single carbon fiber increased. Furthermore, the surface modification of the carbon fibers by magnetron sputtering was conducive to improving the tensile properties of the carbon fibers. The tensile breaking strength of the modified single carbon fiber and multifilament carbon fiber slightly increased. As the magnetron sputtering time was increased, the tensile breaking strength of the carbon fiber further increased. The influence of the carbon film on the surface of the carbon fiber greatly enhanced the tensile fracture toughness using the crack effect mechanism.