Surface Modification Of Carbon Fiber Research Articles

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

Carbon fibers are used in the production of automobiles, airplanes, sporting goods, energy, and biomedicine due to their unique properties such as high specific strength, high specific tensile strength, low coefficient of thermal expansion, and low density. The research and development of both the technology of carbon fibers production and their modification for a wide range of applications have been and remain relevant. The summary of the accumulated experience in the modification of carbon fibers shows that ion-beam treatment allows to obtain a variety of geometry of the developed surface topography, in particular, whisker-shaped and corrugated oriented across or along the fiber. Such processing compares favorably with ordinary fiber whiskering both by a variety of geometry of the composite interface, and by the absence of the problem of whisker-fiber adhesion. Ion-beam treatment also makes it possible to modify the surface layer structure from amorphized to ordered with different degrees of graphitization. Irradiation with chemically active ions leads to functionalization of carbon fiber due to formation, for example, of nitrides and carbon oxides. The choice of nitrogen ions for the technology of carbon-carbon and carbon-ceramic composites seems to be more preferable due to less stringent requirements for the temperature of the irradiated fiber. For ion-beam corrugation of polyacrylonitrile-based carbon fiber surface, only its heating above the temperature of dynamic annealing of radiation damage is required. The use of helium ions in technological plasma acceleration systems leads to a significant efficiency increase in ion-beam processing.

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.

Green composites from vanillin-based benzoxazine and silane surface modified chopped carbon fibers

By following the rules of green chemistry, a novel composite is developed from a renewable and ecofriendly resource, namely, vanillin. The latter was used as a phenolic precursor for the microwave synthesis of a bio-based benzoxazine resin (Va-BZ). Afterward, high-performance green composites were developed by reinforcing Va-BZ with various amounts of chopped silane surface modified carbon fibers (CFs). The chemical structure of the Va-BZ monomers was confirmed by 1H NMR and Fourier transform infrared spectroscopy. The grafting of the silane moiety on the CF surface was assessed by FTIR and TGA analyses. The autocatalytic ring opening polymerization of the Va-BZ monomers was confirmed by DSC analysis. The mechanical performances of the developed green composites were studied by flexural and tensile investigations. The findings suggested that the maximum amount of 20 wt. CFs afforded the best results, with flexural and tensile strengths of 450 and 462 MPa, respectively. The SEM was used to study the fractured tensile surfaces and elucidated the toughening mechanism. Meanwhile, the TGA showed that the introduction of the CFs markedly improved the thermal stability of the benzoxazine matrix. Overall, this study confirmed that greener approaches can also result in high-performance composites satisfying the needs of exigent applications.

Optimization of Electrical Intensity for Electrochemical Anodic Oxidation to Modify the Surface of Carbon Fibers and Preparation of Carbon Nanotubes/Carbon Fiber Multi-Scale Reinforcements

Carbon fiber (CF) reinforced composites are widely used due to their excellent properties. However, the smooth surface and few functional groups of CFs can lead to fiber fractures and pullout, which reduce the service life of the composites. The overall performance of composites can be improved by growing carbon nanotubes (CNTs) on the CF surface. Before this, CF surface should be modified to enhance the loading amount of catalyst particles and thus make the CNTs more uniform. In this paper, CNTs were grown on a CF surface by one-step chemical vapor deposition to prepare multi-scale CNTs/CF reinforcements, and the effects of different methods on the CF surface modification were explored. After setting four intensities of electrochemical anodic oxidation, i.e., 50 C/g, 100 C/g, 150 C/g and 200 C/g, it was found that the distribution and quantity of CNTs were improved under both the 100 C/g and 150 C/g conditions. Considering the influence of electrical intensity on the (002) interplanar spacing of CFs, which affects the mechanical properties of the samples, 100 C/g was finally selected as the optimal electrochemical treatment intensity. This finding provides a reference for continuous and large-scale modification of CF surfaces to prepare CNTs/CF multi-scale reinforcements.

Surface-modified carbon fiber for enhanced electromagnetic interference shielding performance in thermoplastic polyurethane composites

There has been a growing interest in developing carbon-based polymer composites for electromagnetic interference (EMI) shielding materials. To achieve a high EMI shielding performance, the morphology of fillers in composites must be controlled. Although carbon fibers (CFs) have remarkable thermal and electrical properties and low density, their poor dispersion behavior within polymer matrix limits their practical applications as EMI shielding materials. In this study, we report an efficient method to disperse CFs within a thermoplastic polyurethane (TPU) matrix using pyranine-functionalized polyether (polyether–pyranine) as a dispersing agent. polyether–pyranine was grafted on the CF surfaces through π–π interactions between the CF and pyranine groups to produce surface-modified CFs (SCFs). Compared to CFs, the SCFs exhibited an improved dispersion stability within a TPU polymer matrix. Furthermore, a TPU composite with SCFs achieved an enhanced electrical conductivity and EMI shielding performance, which was primarily ascribed to the increased structural connectivity between the SCFs due to excellent dispersion.

Surface Modification of Carbon Fibers by Low-Temperature Plasma with Runaway Electrons for Manufacturing PEEK-Based Laminates.

(1) Background: The paper addresses the effect of carbon fibers (CFs) treatment by low-temperature plasma with runaway electrons on the deformation behavior of the polyetheretherketone (PEEK)-layered composites. (2) Methods: The effect of the interlayer adhesion on the mechanical response of the composites was assessed through the tensile and three-point bending tests. In addition, computer simulations of the three-point bending were carried out with the use of the finite element analysis (FEM) with varying conditions at the "PEEK-CF layers" interface. (3) Results: DRE-plasma treatment during the optimal time of t = 15 min led to formation of a rougher surface and partial desizing of a finishing agent. The shear strength of the layered composites increased by 54%, while the tensile strength and the flexural modulus (at three-point bending) increased by 16% (up to 893 MPa) and by 10% (up to 93 GPa), respectively. (4) Conclusions: The results of the numerical experiments showed that the increase in the stiffness, on the one hand, gave rise to enlarging the flexural modulus; on the other hand, a nonlinear decrease in the strength may occur. For this reason, the intention to maximize the level of the interlayer stiffness can result in lowering the fracture toughness, for example, at manufacturing high-strength composites.

Surface Modification of Carbon Fiber for Enhancing the Mechanical Strength of Composites.

The surface of carbon fibers (CFs) is often modified by multi-walled carbon nanotubes (MWCNTs), and the effect of the interface on the mechanical properties has been reported mostly for epoxy matrices. We achieved effective surface modification of CFs by a simple two-step process to graft a large amount of MWCNTs using a highly reactive polymer to enhance the bonding between CFs and MWCNTs. The first step was the reactive mono-molecular coating of a reactive polymer (poly-2-isopropenyl-2-oxazoline; Pipozo) that has high reactivity with COOH from CFs and MWCNTs. The high reactivity between the oxazoline group and COOH or phenol OH was confirmed for low-molecular-weight reactions. The second step was the coating of MWCNTs from a dispersion in a solvent. This simple process resulted in a substantial amount of MWCNTs strongly bonded to CF, even after washing. The MWCNTs grafted onto CFs remained even after melt-mixing. The effect on the interface, i.e., physical anchoring, led to an improvement of the mechanical properties. The novelty of the present study is that Pipozo acted as a molecular bonding layer between CFs and MWCNTs as a physical anchoring structure formed by a simple process, and the interface caused a 20% improvement in the tensile strength and modulus. This concept of a composite having a physical anchoring structure of MWCNTs on CFs has potential applications for lightweight thermoplastics, such as in the automotive industry.

A micromechanical study of the fatigue behavior of MWCNT-modified carbon fibers/epoxy resin single filament composites subjected to cyclic loadings

This paper presents a comprehensive study on the impact of surface modification of carbon fibers using multiple-walled carbon nanotubes (MWCNTs) to improve the load-transfer capacity of the fiber-matrix interface of an epoxy matrix composite subjected to dynamic loads. The single-fiber fragmentation technique (SFFT) was utilized to characterize the length of interfase damage (IDL) produced by quasi-static and dynamic loadings for linear elastic and plastic strains and the residual efficiency of interfacial stress transfer. A finite element model was used to validate the optical measurement and the extent of interfase damage. Scanning electron microscopy (SEM) corroborated the presence of the MWCNTs on the surface of the carbon fibers. The interfacial shear strength (IFSS) increased by approximately 27.5%, attributed to the carbon nanotubes and a more significant fiber-matrix stress transfer. The application of dynamic loads decreased the mechanical properties of the matrix, premature fragmentation of the carbon fiber, and interfacial damage, which led to a reduction in the interfase load-transfer capacity. However, the incorporation of carbon nanotubes in the interface decreased the adverse effects generated by the application of cyclic loads, mainly the propagation of interfacial damage.

Mechanical and Thermophysical Properties of Carbon Fiber-Reinforced Polyethersulfone.

In this study, the mechanical and thermophysical properties of carbon fiber-reinforced polyethersulfone are investigated. To enhance the interfacial interaction between carbon fibers and the polymer matrix, the surface modification of carbon fibers by thermal oxidation is conducted. By means of AFM and X-ray spectroscopy, it is determined that surface modification changes the morphology and chemical composition of carbon fibers. It is shown that surface modification dramatically increases the mechanical properties of the composites. Thus, flexural strength and the E-modulus of the composites reinforced with modified fibers reached approximately 962 MPa and 60 GPa, respectively, compared with approximately 600 MPa and 50 GPa for the composites reinforced with the initial ones. The heat deflection temperatures of the composites reinforced with the initial and modified fibers were measured. It is shown that composites reinforced with modified fibers lose their stability at temperatures of about 211 °C, which correlates with the glass transition temperature of the PES matrix. The thermal conductivity of the composites with different fiber content is investigated in two directions: in-plane and transverse to layers of carbon fibers. The obtained composites had a relatively high realization of the thermal conductive properties of carbon fibers, up to 55–60%.

Carbon fiber polypropylene interphase modification as a route to improved toughness

This manuscript describes the rapid surface modification of carbon fibers using small molecules for application in polypropylene composites at 10% and 40% weight fractions. Attachment of an n-butylphenyl species onto the fiber surface and incorporation into homo-polypropylene resulted in a significant toughness improvement, of 32% and 30% at 10% and 40% weight fractions respectively, when compared against untreated control samples. Further examination of the embedded fiber length, fiber weight fraction, and polymer thermal properties (e.g. Tm and Tc) showed no differences between untreated and treated samples. However, it is proposed that the mechanical performance changes originated from the installed surface chemistry blending with the polymer phase. This is observed through experimental testing which suggests that the sliding interactions of the fiber-matrix interface has created a material that possesses superior ductility and toughness.

Surface modification of carbon fiber with imidazolium ionic liquids

ABSTRACT Carbon fiber composites are high-performance materials commonly used in advanced applications and their performance is highly dependent on the fiber-matrix interfacial interaction. The non-polar carbon fiber surface may be modified via different techniques to improve adhesion with the polymer matrix. In this work, non-covalent surface modification of carbon fiber has been carried out using two different imidazolium ionic liquids, 1-n-butyl-3-methyl imidazolium bis(trifluoromethylsulfonyl) imide (hydrophobic) and 1-n-butyl-3-methylimidazolium chloride (hydrophilic). The treatment was performed by immersing the fiber into 10 wt. % methanolic ionic liquid solution for 10 min. Treated fibers were characterized using Fourier-transform infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy confirmed the presence of ionic liquid on the carbon fiber surface. Surface morphology of treated fibers analyzed by scanning electron microscopy showed ionic liquid moieties. Wettability of the treated carbon fiber with epoxy resin significantly increased, with a decrease in contact angle greater than 15°. Interfacial shear strength between the modified carbon fiber and epoxy increased up to 56.5% with respect to the unsized carbon fiber, being comparable with epoxy-sized fibers. Thus, the proposed surface modification has the potential to improve the interfacial performance of carbon fiber polymer composites.

Effect of Surface Modification of Carbon Fiber Based on Magnetron Sputtering Technology on Tensile Properties

Effect of Surface Modification of Carbon Fiber Based on Magnetron Sputtering Technology on Tensile Properties

Surface modification of carbon fiber as a protective strategy against thermal degradation

Carbon fibers were surface modified with acrylate-derived polymers with aromatic side chains, to protect the fiber when exposed to high temperatures.The surface modification process induced a significant increase in tensile strength (23.7%) and tensile modulus (8%), for the benzyl-bearing side chain andretained superior tensile strength (20%) and tensile modulus (7%)after heating to 600 °C. Commercialcarbon fibres gave asignificant decrease in tensile strength and modulus, 7% and 4%, respectively, when exposed to the same conditions. This suggests that the surface modification process provides a protective effect against thermal degradation, with possible application in carbon fibre recycling.The interfacial shear strength (IFSS) showed significant improvementbefore (up to 208%) and after (up to 84%) exposure to high temperatures. Analysis of the carbon fiber surface byXPS suggests that the surface bound polymer becomes more graphitic, potentiallyviathe fusion of the aromatic side chains.

Constructing a Rigid-and-Flexible Twin-Stage Gradient Interphase through Starlike Copolymer Coating on Carbon Fibers: A Route for Enhancing Interfacial Properties of Composites.

A rigid-and-flexible interphase was established by a starlike copolymer (Pc-PGMA/Pc) consisting of one tetraaminophthalocyanine (TAPc) core with four TAPc-difunctionalized poly(glycidyl methacrylate) (PGMA) arms through the surface modification of carbon fibers (CFs) and compared with various interphases constructed by TAPc and TAPc-connected PGMA (Pc-PGMA). The increase in the content of N-C═O showed that PGMA/Pc branches were successfully attached onto the CF-(Pc-PGMA/Pc) surface, exhibiting concavo-convex microstructures with the highest roughness. Through adhesive force spectroscopy by atomic force microscopy (AFM) with peak force quantitative nanomechanical mapping (PF-QNM) mode and visualization of the relative distribution of TAPc/PGMA via a Raman spectrometer, a rigid interphase with highly cross-linked TAPc and a flexible layer from PGMA arms as the soft segment were separately detected in CF-TAPc/EP and CF-(Pc-PGMA)/EP composites. The rigid-and-flexible interphase in the CF-(Pc-PGMA/Pc)/EP composite provided excellent stress-transfer capability by the rigid inner modulus intermediate layer and energy absorption efficiency from the flexible outer layer, which contributed to 64.6 and 61.8% increment of transverse fiber bundle test (TFBT) strength, and 33.8 and 40.6% enhancement in interfacial shear strength (IFSS) in comparison with those of CF-TAPc/EP and CF-(Pc-PGMA)/EP composites. Accordingly, schematic models of the interphase reinforcing mechanism were proposed. The interfacial failures in CF-TAPc/EP and CF-(Pc-PGMA)/EP composites were derived from the rigid interphase without effective relaxation of interfacial stress and soft interphase with excessive fiber-matrix interface slippage, respectively. The cohesive failure in the CF-(Pc-PGMA/Pc)/EP composite was attributed to the crack deflection through the balance of the modulus and deformability from the twin-stage gradient intermediate layer.