Surface Properties Of Carbon Fibers Research Articles

Enhancement of interfacial performance of carbon fiber reinforced polypropylene composites by dual action of polyetherimide nanoparticles and coatings

In order to enhance the interfacial bonding between carbon fibers (CFs) and polypropylene (PP) resin, a multiscale modification system of composite interfacial physical embedding-chemical bonding was established by the dual action of polyetherimide (PEI) nanoparticles and coatings prepared on the surface of CFs. Hemispherical PEI nanoparticles were prepared by evaporation-induced treatment to improve the mechanical interlocking ability of the composite interface. Based on PEI nanoparticles, coatings with different concentrations were introduced on the CF surface to exert chemical bonds and enhance compatibility with the PP resin. The surface properties of CFs, including chemical composition, morphology, wettability, and interfacial adhesion were systematically investigated. Compared with unmodified CFs, modified CFs showed increased surface roughness, enhanced surface activity, and improved surface wettability. Due to the dual action of PEI nanoparticles and coatings, the tensile strength and interlaminar shear strength (ILSS) of the composite were both enhanced. Specifically, the ILSS of PCF-0.10/PP composite increased by 119.35%, indicating that the dual modification significantly improved the mechanical reinforcement and interfacial adhesion of the composite. On this basis, the interfacial strengthening mechanism in the composite was proposed, and an effective and feasible method was proposed to improve the interfacial performance of composites. The method has the limitation of a long preparation time, but it is simple, easy, and cost-effective, which provides a promising prospect for the application of composites.

Nanocomposites of Nanocarbon Functionalized Carbon Fibers—Manufacturing to Methodological Applications

Abstract Carbon fibers have been technically applied in high performance materials and industrial scale applications. Importantly, carbon fiber reinforced composite materials have found applications in aerospace industries. These properties of carbon fiber reinforced composites depend upon the carbon fiber features such as length, orientation, surface properties, adhesion with matrices, etc. To improve the surface properties of carbon fibers and adhesion and interactions with polymers, fiber modification has been suggested as an efficient approach. Carbon nanoparticle or nanocarbon functionalized carbon fibers have been manufactured using various facile physical and chemical approaches such as electrospraying, electrophoretic deposition, chemical vapor deposition, etc. Consequently, the modified carbon fibers have nanocarbon nanoparticles such as graphene, carbon nanotube, nanodiamond, fullerene, and other nanocarbons deposited on the fiber surface. These nanocarbon nanoparticles have fine capability to improve interfacial linking of carbon fibers with the polymer matrices. The chemical vapor deposition has been adopted for uniform deposition of nanocarbon on carbon fibers and chemical methods involving physical or chemical modification have also been frequently used. The resulting advanced epoxy/carbon fiber/nanocarbon composites revealed improved tensile and physical profiles. This review basically aims manufacturing and technical aspects of polymer/fiber/nanofiller nanocomposites toward the development of high performance structures. The resulting morphology, strength, modulus, toughness, thermal stability, and other physical features of the nanocarbon functionalized carbon fibers have been enhanced. In addition, the fabricated polymer/fiber/nanofiller nanocomposites have fine interfacial adhesion, matrix-nanofiller-filler compatibility, and other characteristics. The application areas of these nanomaterials have been found wide ranging including the strengthened engineering structures, supercapacitors, shape memory materials, and several others.

The Effect of Temperature on the Surface Energetic Properties of Carbon Fibers Using Inverse Gas Chromatography

This paper constitutes an original and new methodology for the determination of the surface properties of carbon fibers in two forms, namely, oxidized and untreated, using the inverse gas chromatography technique at infinite dilution based on the effect of temperature on the surface area of various organic molecules adsorbed on the carbon fibers. The studied thermal effect showed a large deviation from the classical methods or models relative to the new determination of the surface properties of carbon fibers, such as the dispersive component of their surface energy, the free surface energy, the free specific energy, and the enthalpy and entropy of the adsorption of molecules on the carbon fibers. It was highlighted that the variations in the London dispersive surface energy of the carbon fibers as a function of the temperature satisfied excellent linear variations by showing large deviations between the values of γsd (T), calculated using different models, which can reach 300% in the case of the spherical model. All models and chromatographic methods showed that the oxidized carbon fibers gave larger specific free enthalpy of adsorption whatever the adsorbed polar molecules. The obtained specific enthalpy and entropy of the adsorption of the polar solvents led to the determination of the Lewis acid–base constants of the carbon fibers. Different molecular models and chromatographic methods were used to quantify the surface thermodynamic properties of the carbon fibers, and the results were compared with those of the thermal model. The obtained results show that the oxidized carbon fibers gave more specific interaction energy and greater acid–base constants than the untreated carbon fibers, thus highlighting the important role of oxidization in the acid–base of fibers. The determination of the specific acid–base surface energy of the two carbon fibers showed greater values for the oxidized carbon fibers than for the untreated carbon fibers. An important basic character was highlighted for the two studied carbon fibers, which was larger than the acidic character. It was observed that the carbon fibers were 1.4 times more acidic and 2.4 times more basic. The amphoteric character of the oxidized fibers was determined, and it was 1.7 times more important than that of the untreated fibers This tendency was confirmed by all molecular models and chromatographic methods. The Lewis acid and base surface energies of the solid surface, γs+ and γs−, as well as the specific acid–base surface energy γsAB of the carbon fibers at different temperatures were determined. One showed that the specific surface energy γsAB of the oxidized fibers was 1.5 times larger than that of the untreated fibers, confirming the above results obtained on the strong acid–base interactions of the oxidized carbon fibers with the various polar molecules.

Influence of the electrochemical treatment level of carbon fibers on the compression after impact property of carbon fiber/epoxy composites

AbstractIn this paper, carbon fibers (CF) with different electrochemical treatment levels were obtained by changing the parameters of electrochemical treatment, and the effect of electrochemical treatment levels on the surface properties of CF was studied by scanning electron microscope, atomic force microscopy and X‐ray photoelectron spectroscopy. The interfacial shear strength (IFSS) of CF with different electrochemical treatment levels were characterized by single fiber‐composite fragmentation. The effects of electrochemical treatment on the mechanical properties of CF were investigated by monofilament tensile test and composite laminate 0° tensile test. Finally, the carbon fibers were compounded with epoxy resin to prepare composite laminates, whose effect on the macroscopic mechanical properties of the composite, such as short beam shear strength (SBSS) and compression after impact (CAI) strength, was studied. As a result, with the increase of the level of electrochemical treatment, the surface roughness and chemical activity of CF increased first and then decreased, while the surface energy shows a gradually increasing trend. The IFSS of CF‐BX shows a gradually increasing trend, while that of the CF‐SX shows a trend of increasing first and then remaining basically unchanged, while SBSS shows the same trend. The monofilament tensile test and composite laminate 0° tensile test showed that the electrochemical treatment did not have a significant effect on the mechanical properties of CF. The compression after impact test showed that with the enhancement of the electrochemical treatment, the CAI of the composite laminates increased first and then remained roughly unchanged.

Multi‐walled carbon nanotubes/carbon fiber fabric multiscale hybrid materials for improving the mechanical and tribological properties of phenolic resin composites

AbstractMulti‐walled carbon nanotubes (MWCNT)/carbon fiber fabric multiscale hybrid materials were prepared by grafting MWCNT on carbon fabric surface via heating grafted method to improve the mechanical and tribological properties of phenolic resin composites. Field emission scanning electron microscopy, Raman spectrometer, and X‐ray photoelectron spectroscopy were used to analyze the surface properties of carbon fiber. The results shown that the tensile strength of composites modified by 0.15 wt% MWCNT was 38% higher than that of unmodified composites. The wear rates decreased from 3.31 × 10−14 m3 (N·m)−1 for unmodified composites to 0.68 × 10−14 m3 (N·m)−1 for 0.15 wt% MWCNT reinforced composites. The reason was that the uniformly distributed MWCNT could increase interface interaction and mechanical interlocking between carbon fiber fabric and resin matrix.

Effect of silane coating surface treatment on friction and wear properties of carbon fiber/PI composites

Abstract PAN-based carbon fiber was surface-modified with silane coating, and a composite material was prepared using a PI resin as a matrix. The structure and surface properties of carbon fibers were studied by means of X-ray photoelectron spectroscopy (XPS) and SEM. The tensile strength of the composite was measured by a tensile tester, and the friction properties of the composite were measured by a micro-nano mechanics comprehensive test system. The results show that treatment with silane coating can improve the surface roughness and chemical activity of carbon fiber, improve the interface between carbon fiber and PI resin matrix, and improve the tensile strength and wear rate of the composite.

Effects of acid treatment and plasma micromachining on the surface properties of carbon fibers

The effects of strong acid and weak acid treatment on the carbon cloth (CC) surface assisted by plasma micromachining are investigated in terms of the morphology, chemical composition, and surface free energy. Different surface properties are observed and protein adsorption is investigated to assess the biocompatibility. The combined plasma and acetic acid treatment leads to more surface oxidation due to the large number of carboxyl groups on the CC surface and surface energy increase by 18.6 times. Since the effects of acetic acid are relatively mild, few morphological changes are found, but protein adsorption decreases by about 30% after the surface treatment compared to the untreated CC. The combination of plasma and weak acid treatment is not only simple and convenient, but also very effective in controlling protein adsorption on biomedical carbon cloth.

Improved the surface properties of carbon fiber through hyperbranched polyaryletherketone sizing

AbstractA heat‐resistant soluble hyperbranched polyaryl ether ketone (HPAEK) is synthesized as the main resin of sizing agent and coated on the surface of carbon fiber (CF) with active group. As a result, the monofilament tensile strength of CF is increased by 12.00% and due to the improved fiber surface wettability and interface compatibility between CF and polyether ether ketone (PEEK), a 68.29% increase of interlaminar shear strength is achieved.

Carbon Fiber Surface Functional Landscapes: Nanoscale Topography and Property Distribution.

The ultimate properties of carbon fibers and their composites are largely dictated by the surface topography of the fibers and the interface characteristics, which are primarily influenced by the surface distribution of chemical functionalities and their interactions with the matrix resin. Nevertheless, nanoscale insights on the carbon fiber surface in relationship with its chemical modification are still rarely addressed. Here, we demonstrate a critical insight on the nanoscale surface topography characterization of modified novel carbon fibers using high-resolution atomic force microscopy at multiple length scales. We compare the nanoscale surface characteristics relevant to their role in controlling interfacial interactions for carbon fibers manufactured at two different tensions and two distinct chemically functionalized coatings. We used surface dimple (also known as nanopores) profiling, microroughness analysis, power spectral density analysis, and adhesion and electrostatic potential mapping to reveal the fine details of surface characteristics at different length scales. This analysis demonstrates that the carbon fibers processed at lower tension possess a higher fractal dimension with a more corrugated surface and higher surface roughness, which leads to increased surface adhesion and energy dissipation across nano- and microscales. Furthermore, electrochemical surface modification with amine- and fluoro-functional groups significantly masks the microroughness inherent to these fibers. This results in increased fractal dimension and decreased energy dissipation and adhesion due to the high chemical reactivity in the areas of asperities and surface defects combined with a significant increase in the surface potential, as revealed by Kelvin probe mapping. These local surface properties of carbon fibers are crucial for designing next-generation fiber composites with predictable interfacial strength and the overall mechanical performance by considering the fiber surface topography for proper control of interphase formation.

Effect of carbonization temperature of carbon felt on removal of methylene blue: carbon felt as the cathode of Electro-Fenton system

The surface properties of carbon fiber have been regarded as the critical factor for 2-electron oxygen reduction (ORR) and degradation of organic pollution in Eletro-Fenton process. The aim of this work was to investigate the effect of carbonization temperature on the performance of carbon felt as the cathode for degradation methylene blue (MB). This work was adopted carbon felt that obtained at the carbonization temperature of 1050, 1600, 2000 °C respectively, comparison of the electrogeneration of H2O2 and MB removal rate at pH 3. Compared with CF-B and CF-C, high-yield H2O2 production (38.9 mg L−1, 1.3 mg h−1 cm−2) and high-degradation rate of MB (96.7%, kinetics constant: 0.0623 min−1) in CF-A system have been achieved. The hydrophilic was carried by water contact angle test, indicated that the inert of surface: CF-C > CF-B > CF-A. The disorder degree of surface was characterized by Raman spectroscopy, and in combination with CV and LSV tests, revealed the ORR catalysis properties of different types cathode. This study suggested that lower temperature of carbonization was in favour of carbon felt as the Electro-Fenton cathode to degenerate organic pollution.

Effects of Acid Treatment and Plasma Micromachining on the Surface Properties of Carbon Fibers

Effects of Acid Treatment and Plasma Micromachining on the Surface Properties of Carbon Fibers

Effect of the double bond content of sizing agents on the mechanical properties of carbon fibre reinforced vinyl ester composites

Unsaturated polyester sizing agents with various double bond contents have a significant influence on the interface between carbon fibers (CF) and vinyl ester resins (VER). This paper aims to study the effect of the double bond content of sizing agents on the surface properties of CF and thermo mechanical properties of the sized CF/VER composites. We synthesized five types of self-emulsifying cationic sizing agents with various double bond contents and characterized the samples by FTIR, dynamic light scattering (DLS), cryo-scanning electron microscopy (Cryo-SEM) and thermal gravimetric analysis (TGA). The double bond content of the sizing agents on the cross-linking extent of the CF surface were investigated on factors such as the wettability of VER, the interlaminar shear strength (ILSS) and flexural strength and modulus of CF/VER composites. It was identified that the distribution of the sizing agent emulsions had a mono-dispersion of around 50 nm and were thermally stable below 300 °C. Additionally, it was identified that the double bond content of the sizing agents enhanced the grafting reactions and cross-linking extent between the sizing agent and CF surface. The CF had the best wettability for vinyl ester resin when the double bond content was 10% in the sizing agent. In addition, the ILSS, the flexural strength and the modulus reached maxima.

Effect of Sizing Agents on Surface Properties of Carbon Fibers and Interfacial Adhesion of Carbon Fiber/Bismaleimide Composites.

Physicochemical, surface, and mechanical properties of three batches of T800 grade carbon fibers (CFs) treated with three kinds of sizing agents and Toray T800H CFs were characterized to study the effect of sizing agents on surface properties. Scanning electron microscopy for morphology, atomic force microscopy calculations, and results for the content of sizing agents showed that sizing agent B improved the surface roughness and CFs with high content of sizing agent always presented small surface roughness in a certain content range 1.2–1.6%. Surface energy of CFs was calculated by Young’s contact angle using the test results with water and glycol, and contact angles with LY-1 and modified-AC531 were also acquired. The results proved that CFs of sizing agent group B had the highest average surface energy and the lowest average contact angles with both LY-1 and modified-AC531. From both single-filament and tensile strength test results, the average strength of CFs of sizing agent group B was found to be the lowest, which indicated that sizing agent B had an influence on tensile strength decrease of T800 grade CFs. Comparing the results of interfacial shear strength both in a natural dry state and after hygrothermal treatment, high surface energy was found to be the key element to obtain high interfacial adhesion between T800 grade CFs and bismaleimide, and high surface roughness and low contact angle also played important roles. Among sizing agents A, B, and C, A had an effect on the interfacial shear strength decrease of CFs in the natural dry state, while C had that after hygrothermal treatment.

Effect of polyetherimide sizing on surface properties of carbon fiber and interfacial strength of carbon fiber/polyetheretherketone composites

AbstractThe sizing process is almost invariably performed after the manufacture of carbon fiber (CF) and the sizing agent takes the effect of protecting CF surface. However, the traditional sizing agent is not suitable for processing continuous CF reinforced thermoplastic composites (CFRTPs) with high processing temperature. In this work, polyetherimide (PEI) is chosen as the sizing agent for CF reinforced polyetheretherketone (CF/PEEK) composites, and the sizing content as well as the type of sizing agent (including solvent‐based and emulsion type) were systematically researched. After a series of characterization of CF surface properties and interfacial strength of CF/PEEK, the improvement of interfacial shear strength (IFSS) and mechanical performances of sized CF/PEEK proves the enhancement of interfacial adhesion after sizing. CF/PEEK composites which contain CF handled by emulsion type sizing agent have good mechanical properties, indicating that it has the potential to replace solvent‐based sizing agent. Besides, the miscible feature of PEEK with PEI, the raise of CF surface roughness and surface energy might cause the reinforcement of interfacial mechanical properties. This research may create a potential way for CF production field, aiming at improving the interfacial performance of CFRTPs.

Influence of surface modification of carbon fiber based on magnetron sputtering technology on mechanical properties of carbon fiber composites

To improve the interfacial performance of carbon fiber (CF) and epoxy resin, the surface of CF was modified using magnetron sputtering technology, and a CF epoxy resin (CFER) composite was prepared using injection molding technology. The influence of magnetron sputtering technology on the surface properties of CF was investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), and dynamic contact angle analysis (DCAA). The influence of the surface modification of the CFs by magnetron sputtering on the mechanical and interfacial properties of CF composites was analyzed by testing the tensile and bending properties of the CFER composites. The results indicated that the surface morphology of CF can be modified by magnetron sputtering, and a nano sized carbon film was deposited on the surface of the CFs. The morphology of the carbon film on the surface of the CFs was different from that on the silicon pellet. The surface roughness of the CF increased after it was modified by magnetron sputtering. The surface wettability of the CFs may be improved by increasing the surface free energy of the fiber owing to the deposition of the carbon film. Tests of the tensile and bending properties of the CFER composites showed that the surface modification of CFs by magnetron sputtering can effectively improve the mechanical properties of the CFER composites, which not only improves the tensile strength and bending strength, but also increases the tensile modulus and bending modulus. The SEM images showed that the interfacial adhesion between the modified CF and the epoxy resin was significantly improved. The stress–strain curves showed that the failure mode of the CFER composite modified by magnetron sputtering CF surface changed, and a stress yield phenomenon was observed.

Iron coupling with carbon fiber to stimulate biofilms formation in aerobic biological film systems for improved decentralized wastewater treatment: Performance, mechanisms and implications

Iron coupling with carbon fiber (ICF) as carriers to stimulate the biofilms formation for decentralized wastewater treatment was proposed. The typical pollutants removal was accelerated and enhanced (increased by 13.65% for chemical oxygen demand, 19.68% for ammonia nitrogen and 32.66% for phosphate) in ICF compared with the traditional carbon fiber (CF) system. Mechanism explorations indicated that the iron coupling improved the surface properties of carbon fibers and contributed to the attachment and growth of biomass significantly. The components of biomass were changed with increasing proteins proportion in ICF, which was beneficial to the biofilms formation and stability. The microbial community was altered with the enrichment of functional microorganisms (i.e. Pseudomonas and Thauera). Moreover, the microbial metabolic functions (i.e. enzymatic activities and encoding genes) involved in pollutants removal derived from decentralized wastewater were highly expressed in ICF. This work provided an effective strategy to enhance the decentralized wastewater treatment.

Enhanced Surface Properties of Carbon Fiber Reinforced Plastic by Epoxy Modified Primer with Plasma for Automotive Applications.

Carbon fiber reinforced plastic (CFRP) is currently used as a lightweight material in various parts of automobiles. However, fiber reinforced plastic (FRP) material may be damaged at the time of joining via mechanical bonding; therefore, adhesion is important. When bonding is conducted without surface CFRP treatment, interfacial destruction occurs during which the adhesive falls off along with the CFRP. Mechanical strength and fracture shape were investigated depending on the surface treatment (pristine, plasma treatment times, and plasma treatment times plus epoxy modified primer coating). The plasma treatment effect was verified using the contact angle and X-ray photoelectron spectroscopy. The wettability of the epoxy modified primer (EMP) coating was confirmed through surface morphology analysis, followed by observation of mechanical properties and fracture shape. Based on test data collected from 10 instances of plasma treatment, the EMP coating showed 115% higher strength than that of pristine CFRP. The adhesive failure shape also changed from interfacial failure to mixed-mode failure. Thus, applying an EMP coating during the automotive parts stage enhances the effect of CFRP surface treatment.

A Practical Approach for Validation of Aptitude of Sized Carbon Fibers for the In-Mould -Impregnation Process

As a new and innovative processing method for carbon fiber reinforced thermoplastic composites, the In-Mould-Impregnation process (IMI) adopts carbon fibers as a heating element by electrical conduction. During heating of the dry carbon fibers in the production process, temperatures up to over 500°C can occur. However, the surface properties of carbon fibers and sizing may change under such conditions and thus affect the resulting composite. The present study is a practical approach to validate the suitability of sized carbon fibers for the IMI. The influence of a thermal treatment according to the parameters of the IMI-Process on carbon fiber-thermoplastic matrix interfacial adhesion was investigated by means of micromechanical and optical test methods. The experimental results demonstrate that the thermal treatment of carbon fibers causes a reduction of tensile strength of single fibers. It does not show an influence on the micromechanical breaking behavior in a PA 6 composite but the surface tension of carbon fibers changes. The change in surface tension can affect the wettability of the carbon fiber with a thermoplastic matrix.

Combining Carbon Fibers with Ni/γ–Al2O3 Used for Syngas Production: Part A: Preparation and Evaluation of Complex Carrier Catalysts

To promote the adsorption and activation of carbon dioxide in the dry reforming of methane (DRM), Ni and Al2O3 were coprecipitated on activated carbon fibers (ACF). Various characterization methods were adopted in order to investigate the surface characteristics of different catalysts. Chemisorption characterization results, such as H2-temperature programmed reduction (H2-TPR), H2-temperature programmed desorption (H2-TPD), and CO2-temperature programmed desorption (CO2-TPD) illustrated that ACF in a nickel-based catalyst could enhance the basic sites and improve the metal dispersion on a catalyst surface, which is beneficial for the adsorption and activation of feed gas. The coprecipitated coating on ACF proved by scanning electron microscope (SEM) can prevent the carbon of ACF from participating in the reaction, while retain good surface properties of carbon fibers. X-ray diffraction (XRD) patterns illustrated that the ACF in a nickel-based catalyst could decrease the crystallite size of the spinel NiAl2O4, which is beneficial for methane reforming. In addition, the Fourier transform infrared spectroscopy (FTIR) of different catalysts revealed that the added ACF could provide abundant functional groups on the surface, which could be the intermediate product of DRM, and effectively promote the reaction. Different to the catalyst supported on single alumina, the performance evaluation and stability test proved that the catalyst added with ACF exhibited a better catalytic performance especially for CO2 conversion. Moreover, based on the characterization results as well as some related literature, the dry reforming mechanism over optimum catalyst was derived.

Effect of preheat treatment on carbon fiber surface properties and fiber/PEEK interfacial behavior

In this work, the effect of preheat treatment on surface properties of carbon fiber (CF) and interfacial properties of CF‐reinforced polyether ether ketone (CF/PEEK) composites was investigated in detail. The sized T700SC CFs were preheated based on practical thermoplastic composites processing conditions. The obvious mass loss was obtained due to the sizing agent degradation. Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy demonstrated that the concentration of sizing agents and activated carbon atoms decreased apparently for preheated fibers. Preheat treatment had negligible effect on tensile strength. Transcrystallinity structures were observed at fiber/PEEK interfaces using polarizing microscope and they had similar transcrystallinity density before and after preheat treatment. The microbond test was performed to determine interfacial shear strength (IFSS) between fibers and PEEK matrix. The IFSS increased from 40.16 to 46.32 MPa by 15.34%, which was against the trend of activated carbon atoms. Furthermore, the mechanisms of interfacial adhesion enhancement were discussed. The sizing layer became weak interface region because of poor chemical bonding between sizing agents and PEEK. Removing sizing via preheat treatment could enhance the interfacial adhesion. POLYM. COMPOS., 40:E1407–E1415, 2019. © 2018 Society of Plastics Engineers