Surface Treatment Of Carbon Fibers Research Articles

Synthesis, pyrolysis of a novel carborane ceramic precursor, and coating on carbon fiber

A novel carborane–carbosilane–(cyclo-silazane) polymer has been synthesized as precursor of ceramic and applied to the surface treatment of carbon fiber (Cf) by precursor infiltration and pyrolysis method. The preparation of carborane precursor was carried out by hydrosilylation of trivinyltrimethylcyclosilazane with dimethylchlorosilane firstly, and then by polycondensation reaction with hydroxylated 1,1′-hydroxysilylene-2,2′-bis(hydroxydimethylsilyl)biscarborane whose −OH was formed by transferring the newly introduced C–H bond via hydroxylation. Chemical structure of the polymer was studied by liquid-nuclear magnetic resonance while evolution of various ceramic phases was studied by Fourier transform infrared spectroscopy and the thermal curing process was studied by thermogravimetric/differential thermal analysis and pyrolysis-gas chromatography/mass spectrometry. The cross-linked polyborosilazane precursor exhibited higher ceramic yield of 65.6% at 1000°C. The coating on the Cf was identified to be uniform, relatively smooth, and continuous with a thickness ranged from 0.1 to 0.5 μm through scanning electron microscope and energy dispersive spectroscopy. Thermogravimetric analysis revealed high temperature stability of the coated Cf in flowing air up to 600°C.

Improvement of the Interfacial Adhesion Between Fiber and Matrix

Abstract In this work, the influence of carbon fiber surface treatment on mechanical properties of unsaturated polyester was investigated. Two approaches have been used in the surface treatment; the first is the desizing of the carbon fiber by the release of the epoxy layer. The second is with the release of epoxy layer and etching the fibers. It was concluded that both methods give good results on adhesion between the matrix and the fibers. It is found that the treatment of carbon fibers is efficient and greatly improves the CFRP handress. The tensile strength of composite materials increases by 30% for etched carbon fibers compared to untreated carbon fibers.SEM images confirm the results obtained.

Electrolytic Surface Treatment for Improved Adhesion between Carbon Fibre and Polycarbonate.

To achieve good mechanical properties of carbon fibre-reinforced polycarbonate composites, the fibre-matrix adhesion must be dialled to an optimum level. The electrolytic surface treatment of carbon fibres during their production is one of the possible means of adapting the surface characteristics of the fibres. The production of a range of tailored fibres with varying surface treatments (adjusting the current, potential, and conductivity) was followed by contact angle, inverse gas chromatography and X-ray photoelectron spectroscopy measurements, which revealed a significant increase in polarity and hydroxyl, carboxyl, and nitrile groups on the fibre surface. Accordingly, an increase in the fibre-matrix interaction indicated by a higher interfacial shear strength was observed with the single fibre pull-out force-displacement curves. The statistical analysis identified the correlation between the process settings, fibre surface characteristics, and the performance of the fibres during single fibre pull-out testing.

The effects of HNO3-surface treated carbon fiber and nano-CaCO3 inclusions on dynamic mechanical and heat properties of PA6/ABS-based composites

Carbon fibers (CFs) were surface treated using nitric acid (HNO3). Afterward, polyamide 6/acrylonitrile–butadiene–styrene (PA6/ABS)-based hybrid nanocomposites containing 10 wt% of HNO3-treated short CFs and 0, 2, 5, and 8 wt% of calcium carbonate (CaCO3) nanoparticles were produced using a counter-rotating twin-screw extruder and injection molding machine. Scanning electron microscopic observations showed the formation of strong interaction between surface-treated CFs and polymer matrix. Dynamic mechanical thermal (DMTA) and thermoanalytical assessments were carried out. DMTA results indicated considerable improvements of storage modulus and viscose damping, in a wide range of temperature, by incorporating surface-treated CFs and CaCO3 nanoparticles. The glass transition temperatures of composites were noticeably greater than that of neat polymer because of the restriction effects of the fibers and nanoparticles on polymer chain mobility. Surface-treated CF and CaCO3 inclusions considerably elevated the heat of fusion and crystallinity. Results of thermogravimetric analyses indicated noticeable higher thermal stability against decomposition for composites as compared to the neat polymer. The adhesion of PA6/ABS polymer to surface-treated CFs and the presence of nanoparticles in polymer–fiber interphase were considered to be the key factors in determining the properties of composites.

Tribological properties of carbon fiber toughened SiC prepared by hot pressing sintering

Csf/SiC composites were prepared by hot press sintering to improve the service performance and wear-resistance of SiC. Surface treatment of short carbon fibers was carried out based on air oxidation and liquid oxidation methods. The dispersion and damage of fibers were investigated after surface treatment. There were less particles and some obvious grooves on the surface of carbon fibers treated by concentrated nitric acid (68%) for 90 min. The optimal air oxidation temperature ranged from 420° to 430°C. The best milling time was 48 h for dispersion uniformity and low injury degree. Composites with low(≤ 30 vol%) fiber content were dense, and fibers were evenly distributed in the matrix without agglomeration. The friction coefficients of Csf/SiC composites decreased with increasing fiber content. Specifically, the friction coefficient of Csf/SiC composite with 55 vol% Csf reached to 0.23. The wear rates firstly decreased to the minimum 2.65 × 10−6 mm3/N·m when 30 vol% Csf was added, and then increased with increasing fiber content. To some degree, this study presented an effective way to enhance the service performance and wear-resistance of SiC.

Comparison of different surface treatments of carbon fibers used as reinforcements in epoxy composites: Interfacial strength measurements by in-situ scanning electron microscope tensile tests

In-situ characterization of the fiber/matrix interfacial failure behavior at microscopic scale is important to optimize the fiber surface treatment and to design high performance composites. In this study, in-situ tensile tests in scanning electron microscope (SEM) were used to investigate the interfacial adhesion strength of epoxy composites reinforced by four kinds of carbon fibers (CF)—raw CF, desized CF, carbon nanotube-grafted CF (CNT-CF) and oxidized CNT-CF. The crack initiation position and fracture failure mode were well recorded. The strains and the interfacial adhesion strength were obtained for these four kinds of composites. It was found that the interfacial strength decreased from 53 MPa to 48 MPa after removing the sizing on carbon fiber surface. However, by grafting CNTs on the CF surface, the interfacial strength reached 55 MPa and was further increased to 58 MPa after a simple thermal oxidation treatment. Moreover, energy dispersion X-ray analysis (EDX) was carried out using scanning transmission electron microscopy (STEM). The EDX mapping demonstrated that oxygen aggregated at the interfaces of raw CF/epoxy and oxidized CNT-CF/epoxy. Thus, a combination of CNT grafting with chemical functionalization should be necessary to achieve high performance carbon fiber reinforced polymer composites.

A novel mild method for surface treatment of carbon fibres in epoxy-matrix composites

The interface quality between the reinforcement and the host matrix plays a key role in the mechanical performance of Carbon Fibre/Epoxy Resin (CFRP) composites. In most cases, an adequately strong interfacial bond is induced chemically either by the oxidation of the carbon fibre (CF) surface and/or by means of mechanical interlocking (friction). Here, a mild chemical process involving CF's functionalization via an epoxidation reaction at room temperature (RT) is being proposed. By immersing the CF in an organic solution (chloroperoxybenzoic acid in dichloromethane), the outer surface is functionalized with oxygen moieties, such as epoxy rings, at optimized grafting densities. The room-temperature method described here is more advantageous that other oxidative treatments since it is cost-effective, environmentally friendly and does not damage the fibre surface. Furthermore, as detected by Laser Raman microscopy a considerable 2.3-fold increase of the maximum interfacial shear stress was observed for the treated CF/Epoxy systems as compared to the pristine-untreated-samples.

Surface treatment of carbon fibres for interfacial property enhancement in composites via surface deposition of water soluble POSS nanowhiskers

This study reports for the first time the use of water soluble sulfonated octa-phenyl POSS nanowhiskers for the surface treatment for carbon fibres using simple dip-coating method. The water soluble nature of the functionalized POSS makes it appealing from a formulation perspective as it can be applied simply using an aqueous media. The synthesis of the water soluble SOP-POSS was achieved via one-step aromatic electrophilic sulfonation of octaphenyl POSS. Collective results from NMR, XPS and FTIR analysis confirmed the meta mono-substitution of all phenyl rings in the starting material with a sulfonic group, leading to its water solubility. Surface treatment of commercially oxidized and unsized carbon fibres was achieved via simple dip-coating of the fibres in an aqueous media solution containing the synthesized SOP-POSS product. After the dip-coating process, the carbon fibres are homogeneously covered with surface adsorbed SOP-POSS nanowhiskers. Physico-chemical characterization of the fibres investigated by Inverse Gas Chromatography (IGC) revealed an improvement in surface chemical homogeneity associated with a significant increase in surface oxygen contents and an overall level of surface polarity comparable to commercially sized fibres. The interfacial adhesion properties between the treated carbon fibres and an epoxy matrix were investigated by single fibre fragmentation technique. The results of the tests revealed that significant enhancement of interfacial properties was achieved as a result of a combination of physical inter-molecular interactions at the fibre-matrix interface and localized nano-mechanical strengthening of the epoxy. The outcomes of this research lay the path forward for a potential simple surface treatment of commercial carbon fibres for Interfacial property improvement in composites.

The Effect of Different Surface Treatments of Carbon Fibers and Their Impact on Composites

The Effect of Different Surface Treatments of Carbon Fibers and Their Impact on Composites

Simulations of Potential Distribution and Efficiency Optimization in Carbon Fiber Electrochemical Oxidation

Electrochemical process is used in carbon fiber surface treatment predominantly. The cell parameters like voltage and current are usually given in average. However, because carbon fiber's resistance is quite high, the electricity potential along the fiber tow decreases rapidly, which affects not only the results but also the efficiency. Nevertheless, no literature has talked about this until now. In this paper we set up a model and got a series of formulas, apparently for the first time, capable of simulating the distributions of potential and current along a carbon fiber tow, and power consumption under different cell parameters such as fiber gauge and electrode distance. Through analysis we found that under a certain voltage between the fiber roller and the graphite cathode, the longer the fiber length soaked in the bath, the greater the attenuation of potential and current along fiber tow, and the more the useless power was consumed. It is probably considered that the distance between carbon fiber tow and graphite cathode should be as close as possible, however, when the distance was too close, the potential decayed much sharply, resulting in low efficiency. The model or the formulas can help find the optimum choice of cell parameters.

Interfacial and Glass Transition Properties of Surface-Treated Carbon Fiber Reinforced Polymer Composites under Hygrothermal Conditions

Interfacial and Glass Transition Properties of Surface-Treated Carbon Fiber Reinforced Polymer Composites under Hygrothermal Conditions

Recent advances in carbon-fiber-reinforced thermoplastic composites: A review

Abstract Carbon fibers (CFs) have high specific tensile strength, high modulus, and outstanding wear resistance, and are widely used for the reinforcement of advanced composite materials. CF-reinforced thermoplastic composites have received much attention because of their easy processability and recycling convenience compared with thermosetting composites. Surface treatment of CFs is generally employed to increase the surface functional groups and interfacial adhesion between the CFs and the surrounding polymer matrix. In this review, we explore recent advances in the surface treatment of CFs and preparation of CF/thermoplastic composites. The thermal, mechanical, and electrical properties of the composites are also discussed.

The effect of surface treatment of CF and graphene oxide on the mechanical properties of PI composite

Present investigation elucidates the effect of surface treatment on the mechanical response of carbon fiber (CF)/polyimide (PI) composite loaded with a range of graphene oxide (GO) content. Incorporation of 0.5 wt% GO in CF/PI exhibited 21.1% improvement in flexural strength. The state of interface and its impact on the tensile behavior at various testing temperatures have been discussed. Scanning electron microscope (SEM) analysis of fractured surfaces has been carried out to comprehend various interfacial strengthening and failure micromechanisms. Surface-treated CFs were incorporated into PI matrix to fabricate a high-performance multiscale composite. To improve the stress transfer between PI and CFs, GO was also grown on fibers to produce GO-grown short CFs. The synergic reinforcing effects of combined fillers were analyzed on the fracture surface of composites through SEM.

Surface treatments of solvated mesophase pitch-based carbon fibers

The effects of oxidation treatments and surface coating on the surface properties of the solvated mesophase pitch-based carbon fiber (CF) are investigated to improve the mechanical properties of the potentially low-cost CF composites. The CFs were treated with air, O3, CO2/H2O, or HNO3 solution or modified with an epoxy coating. The surface of the treated fibers was characterized by adsorption of methylene blue, NaOH uptake, fragmentation test, composite flexural test, and optical microscopy and SEM examination. Gaseous oxidization is considered a suitable and economical process for this potentially low-cost and low packing density CFs. O3 oxidation is more effective than other oxidation treatments and introduces more acidic functional groups and a suitable surface area on the surface of the treated CFs, leading to a shorter fiber critical length and higher interfacial shear strength between the CF and the epoxy resin. Surface coating in 5 wt% of epoxy/acetone solution also effectively reduces fiber critical length due to improved fiber surface wettability. After surface treatment, the CFs can be directly fabricated into composite materials without weaving and knitting. Increased flexural strength and modulus of the composites are achieved by the use of O3-oxidized fibers and fiber surface coatings. Optical microscopy and SEM confirm that the composites fabricated with the surface-treated fibers have less debonded area or voids than the untreated ones.

Plasma treatment of carbon fiber on the tribological property of polyimide composite

The effect of different ratios of carbon fiber (CF) reinforcing polyimide (PI) and surface treatment of CF on the microstructure and wear resistance of surface layers was studied. The increase of CF content led to a gradual increase in the Interlaminar shear strength (ILSS) values, and the maximum ILSS value arises when the CF content is 15 vol%, with an improvement of 13.45% compared to virgin CF composites. The increased interfacial adhesion could be contributed mainly to the presence of branched PI at the interface region. SEM of the worn surface confirms that the plasma treatment efficiently improves the interfacial adhesion of CF/PI composite. Copyright © 2017 John Wiley & Sons, Ltd.

Methyltrimethoxysilane plasma polymerization coating of carbon fiber surfaces

The adjustment of carbon fiber surface properties represents an important aspect to improve the adhesion behavior and the stress transfer between carbon fibers and polymeric matrices in carbon fiber reinforced polymers. In the presented work the surface of continuous carbon fiber tows composed out of 50,000 single fibers, so called 50k tows, is modified by an atmospheric plasma jet treatment of combined plasma activation and plasma polymerization, to improve adhesion to an epoxy matrix. Methyltrimethoxysilane is used as precursor gas to deposit a silicon organic layer. The developed experimental setup allows stable plasma treatment of more than 1200m of 50k carbon fibers, which were shown to be textile processable, and thus represents a promising route for surface treatment of carbon fibers for composite production. Largely homogeneous plasma deposition along and across the 50k carbon fiber tow is demonstrated by chemical surface analysis and high resolution microscopy. Single fiber mechanical properties are preserved under the plasma treatment.

Effect of microstructure on the plasma surface treatment of carbon fibres

Carbon fibres are leading reinforcements in composite materials because of their outstanding mechanical and physical properties. However, the graphitic surface of these fibres is relatively inert, and the weak interaction between the carbon fibres and the polymeric matrix has negative consequences for the mechanical properties of composite materials. Surface treatments have been used to increase the surface roughness, remove contaminants or weakly bonded layers, and to alter the surface chemistry and wettability of the fibres. In this article, the authors review the effect of the microstructure on the response of the carbon fibres to the surface treatments. The observations from conventional carbon fibres and functionalisation techniques are extrapolated to plasma surface treatments and to novel carbon fibres produced from bio-precursors.

The effects of surface treated carbon fibers and CaCO3 nanoparticles inclusions on the mechanical performances of PA6/ABS-based composites

The mechanical and morphological characteristics of PA6/ABS (60/40)-based hybrid composite containing HNO3-treated short carbon fibers (HSCF) and CaCO3 nanoparticles have been experimentally studied. A counter-rotating twin-screw extruder and an injection molding machine were employed to produce different samples containing 10 wt % of HSCF and 0, 2, 5 and 8 wt % of CaCO3 nanoparticles. The SEM observations indicated high-quality adhesion between HNO3-surface treated carbon fibers and PA6/ABS polymer matrix. In addition, the morphological studies showed that the inclusion of CaCO3 nanoparticles caused a significant effect on the ABS particle dispersion in PA6/ABS matrix. The mechanical properties assessments revealed that the incorporation of 10 wt % HSCF into the PA6/ABS can significantly improve tensile strength (82%), tensile modulus (107%), flexural strength (98%), flexural modulus (104%) and impact resistance (24%). The inclusion of CaCO3 nanoparticles, in the presence of 10 wt % HSCF, led to the noticeable improvements of tensile strength (128% for 2 wt % CaCO3), tensile modulus (199% for 5 wt % CaCO3), flexural strength (146% for 5 wt % CaCO3), flexural modulus (204% for 5 wt % CaCO3) and impact resistance (46% for 2 wt % CaCO3). The surface treatment of carbon fibers, dispersion conditions of nanoparticles and ABS phase in polymeric matrix were found to be the major important factors affecting the mechanical properties.

Effect of a multiscale reinforcement by carbon fiber surface treatment with graphene oxide/carbon nanotubes on the mechanical properties of reinforced carbon/carbon composites

An effective carbon fiber/graphene oxide/carbon nanotubes (CF-GO-CNTs) multiscale reinforcement was prepared by co-grafting carbon nanotubes (CNTs) and graphene oxide (GO) onto the carbon fiber surface. The effects of surface modification on the properties of carbon fiber (CF) and the resulting composites was investigated systematically. The GO and CNTs were chemically grafted on the carbon fiber surface as a uniform coating, which could significantly increase the polar functional groups and surface energy of carbon fiber. In addition, the GO and CNTs co-grafted on the carbon fiber surface could improve interlaminar shear strength of the resulting composites by 48.12% and the interfacial shear strength of the resulting composites by 83.39%. The presence of GO and CNTs could significantly enhance both the area and wettability of fiber surface, leading to great increase in the mechanical properties of GO/CNTs/carbon fiber reinforced composites.

An effective surface modification of carbon fiber for improving the interfacial adhesion of polypropylene composites

A simple and effective modification for carbon fiber (CF) was presented in our work. CF was coated with ethylene–methyl acrylate–glycidyl methacrylate (E–MA–GMA) terpolymer through solution dipping. A uniform layer of 2.0wt.% E–MA–GMA was confirmed on CF by IR, TGA and SEM. XPS showed that surface oxygen-containing functional groups were obviously increased after modification, which were advantageous to promote the reactivity of CFs. The treatment turned out to be helpful in enhancing the interfacial adhesion by micro-droplet experiment and the interfacial shear strength was 157% higher. The physical properties of PP/mCF composites were improved by static and dynamic mechanical analysis and the improvement was more noteworthy when maleic anhydride grafted PP (MAPP) was added to the matrix, which was consistent with the fracture morphology. The ultimate flexural strength, impact energy and tensile strength were increased by 139.3%, 233.9% and 126.1%. Besides, the mechanical performance of PP composites with 0–30wt.% CFs were all significantly enhanced by CF surface treatment in combination with MAPP modification. We believed that the excellent performance was not caused by fiber length or crystallinity, it was mainly due to the superior interfacial interaction by intermolecular chain entanglement, as well as chemical reaction between E–MA–GMA and MAPP.