Improved interfacial properties of carbon fiber/UHMWPE composites through surface coating on carbon fiber surface

Carbon fibers were coated in an attempt to improve the interfacial properties between carbon fibers and ultra‐high molecular weight polyethylene resin matrix. Atomic force microscopy, scanning electron microscopy, and X‐ray photoelectron spectroscopy were performed to characterize the changes of carbon fiber surface. Atomic force microscopy results show that the coating of carbon fiber significantly increased the carbon fiber surface roughness. X‐ray photoelectron spectroscopy indicates that silicon containing functional groups obviously increased after modification. Interlaminar shear strength was used to characterize the interfacial properties of the composites.     

碳纤维表面改性研究进展

碳纤维因其优异的综合性能常被用作树脂基体的增强材料.然而由于碳纤维与树脂基体之间的界面结合性能较差,其增强的复合材料的力学性能往往与理论值相差甚远,因此必须对碳纤维进行表面改性,以提高其与聚合物基体的界面粘结性能.本文作者综述了国内外关于碳纤维表面改性技术的研究进展,概述了涂层法、氧化法、高能辐射法等改性方法对碳纤维增强复合材料界面强度的改性效果.     

Effect of the comonomer addition sequence in the synthesis of an acrylonitrile terpolymer on the solution rheology and fiber properties

Polyacrylonitrile terpolymers based on acrylonitrile, acrylic acid, and methyl acrylate were synthesized by reversible addition–fragmentation chain-transfer polymerization with varying the monomer addition sequence during the synthesis. The monomer introduction sequence in the synthesis of a ternary copolymer significantly affects both the rheological properties of solutions and the strength of obtained fibers.     

Effect of carbon fiber surface functionality on the moisture absorption behavior of carbon fiber/epoxy resin composites

Polyacrylonitrile (PAN)‐based carbon fibers were electrochemically oxidized in aqueous ammonium bicarbonate with increasing current density. The electrochemical treatment led to significant changes of surface physical properties and chemical structures. The oxidized fibers showed much cleaner surfaces and increased levels of oxygen functionalities. However, it was found that there was no correlation between surface roughness and the fiber/resin bond strength, i.e. mechanical interlocking did not play a major role in fiber/resin adhesion. Increases in surface chemical functionality resulted in improved fiber/resin bonding and increased interlaminar shear strength (ILSS) of carbon fiber reinforced epoxy composites. The relationship between fiber surface functionality and the hydrothermal aging behavior of carbon fiber/epoxy composites was investigated. The existence of free volume resulted from poor wetting of carbon fibers by the epoxy matrix and the interfacial chemical structure were the governing factors in the moisture absorption process of carbon fiber/epoxy composites. Copyright © 2016 John Wiley & Sons, Ltd.     

Investigation of surface topography, morphology and structure of amorphous carbon films by AFM and TEM

Morphology and structure of amorphous carbon films deposited with a pulsed arc source (LASER-ARC) have been studied using microscopical methods (SEM, TEM and AFM), electron diffraction and spectroscopical investigation (EELS). The parameters of the arc source and the deposition conditions (substrate temperature) influence morphology and structure of deposited amorphous carbon films. Especially the incorporation and growth of particles, embedded in the film have been investigated. By particle analysis using an optical microscope a majority of particles that is smaller than 500 nm has been determined. The morphology has been also demonstrated similar by AFM and TEM images. Their number and size of particles is strongly influenced by the deposition temperature. The structure of amorphous film is characterized by the EELS-spectra, but the particle structure was not detectable.     

Determination of isoniazid and hydrazine by capillary electrophoresis with amperometric detection at a Pt-particle modified carbon fiber microelectrode

Capillary electrpphoresis (CE)/electrochemical detection (EC) for the simultane-ous determination of hydrazine and isoniazid has been developed.The electrochemical method uses a novel modified electrode dispersed with ultrafine platinum particles on the surface of a 30μm carbon fiber microelectrode.The unique characteristic of the Pt-particles modified carbon fiber microelectrode is its excellent stability.The current measurement for hydrazine is more sensitive than that of isoniazid.Selective determination of trace amount of free hydrazine in isoniazid and its formulation can be achieved at applied potential of 0.5V.     

Effect of carbon fiber surface treatments on the flexural strength and tribological properties of short carbon fiber/polyimide composites

Pitch‐based short carbon fibers (CFs) were treated by air oxidation and cryogenic nitrogen, respectively. Thereafter the treated and untreated CFs were incorporated into polyimide (PI) matrix to form composites. The CFs before and after treatment were examined by XPS and SEM.The flexural strength of the specimen was determined in a three‐point test machine and the tribological properties of PI composites sliding against GCr15 steel rings were evaluated on an M‐2000 model ring‐on‐block test rig. The results show that the surface of the treated CFs became rougher. Lots of active groups formed on the CF surface after air oxidation.The treatment can effectively improve the mechanical and tribological properties in their PI composites due to the enhanced fiber‐matrix interfacial bonding. Copyright © 2008 John Wiley & Sons, Ltd.     

Influence of surface properties of graphene oxide/carbon fiber hybrid fiber by oxidative treatments combined with electrophoretic deposition

An effective way to prepare graphene oxide/carbon fiber hybrid fiber was proposed by the treatment with hydrogen peroxide and concentrated nitric acid combined with electrophoretic deposition process. Surface functional group, surface roughness, and surface morphologies of carbon fibers were examined by Fourier transform infrared spectrometer, atomic force microscopy, and scanning electron microscopy. Results showed that a uniform and thick graphene oxide films were constructed on the surface of carbon fiber. Deposition density increased by introduction of pretreatment of the carbon fiber in the electrophoretic deposition process has been shown as a possible method. Dynamic contact angle analysis results indicated that the deposition of graphene oxide significantly improved surface free energy of carbon fiber by increasing surface area and polar groups. The introduction of graphene oxide in the carbon fiber‐reinforced epoxy composites results in a 55.6% enhancement in the interfacial shear strength and confirms the remarkable improvement in the interfacial adhesion strength of the composites, and the fracture mechanism was also analyzed. Copyright © 2016 John Wiley & Sons, Ltd.     

碳纳米管修饰碳纤维超微圆柱电极的研制与应用

制作了碳纳米管修饰碳纤维组合电极(EUME-CNT),研究了木犀草素在EUME-CNT上的电化学行为,并且通过优化测定参数,建立了木犀草素的电化学分析方法。检出限达到4×10-7mol/L,线性范围为6×10-7~1×10-5mol/L。     

The surface modification of carbon fiber for thermoplastic HDPE composites

The interfacial adhesion strength between the fiber and the matrix greatly affects the properties of the carbon fiber (CF)–reinforced composite. The presence of surface functional groups on the fiber and changes in surface roughness were determined by X-ray photoelectron spectroscopy, scanning electron microscopy (SEM), and Raman spectroscopy. The effect of surface modification of CF on the mechanical properties and tribological properties of the composites is enhanced. The performance has been significantly improved. SEM analysis showed that modification had a positive effect on the interface between fiber and matrix. In the paper, the method of CF modification and the treatment of enhanced high-density polyethylene have simple and effective characteristics, which can be widely used and have guiding significance for industrial production.     

Rapid determination of comonomer content,crystallinity, and long spacing by multiple-pulse proton NMR in ethylene–vinyl alcohol copolymers

Capitalizing on the superior sensitivity of proton NMR, relatively rapid estimates of three parameters, namely, comonomer content, crystallinity, and long spacing, are determined for three ethylene/vinyl alcohol copolymers using solid-state proton NMR measurements. Multiple-pulse techniques are utilized (a) in conjunction with magic angle spinning for measuring comonomer content, (b) in conjunction with a T_1xz relaxation measurement for determining crystallinity, and (c) in conjunction with a T_1xz-based spin diffusion measurement for determining the long spacing. These three parameters, extracted from data collected in a total spectrometer time of about 20 min, are compared with similar parameters obtained using more conventional DSC, SAXS (including synchrotron), and solution-state NMR measurements. Agreement is found to be good. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2103–2109, 1998     

利用AFM和SNOM对淋巴细胞膜表面超微结构及其光学性质的初步研究

利用原子力显微镜(Atomic Force Microscopy，AFM)对淋巴细胞表面形貌进行了形态学的初步研究，观察到了其膜表面其他显微技术所不能发现的超微结构．同时也运用扫描近场光学显微镜(Scanning Near field Optical Microscopy，SNOM)对淋巴细胞进行成像，观察了其对光的透射、吸收等光学性质，并对两种成像方法进行了比较．研究发现：淋巴细胞膜表面凹凸不平，分布着大量直径几十到几百纳米不等的小颗粒；淋巴细胞中央部位有自发荧光现象．结果表明，AFM和SNOM可作为进一步探讨淋巴细胞的结构与功能关系的有力工具．     

Synthesis, characterization and surface properties of amphiphilic polystyrene-b-polypropylene glycol block copolymers

The new macroazoinitiators containing poly (propylene glycol), (PPG), with molecular weight 400 and 2000, having hydrophilic character, were synthesized and polymerized with styrene to prepare PS-b-PPG block copolymers. Cast films and e-spun films were prepared and contact angles of these films with water drop were measured to examine hydrophilic/hydrophobic behavior of the copolymers. Each e-spun film with average fiber diameters from 0.25 to 2.20 μm was prepared in N,N-dimethylformamide (DMF) under controlled electrospinning process parameters such as polymer concentration, applied voltage and tip-to-collector distance. Scanning electron microscope (SEM) images of the electrospun films were taken to determine the fiber diameters. Surface compositions of the block copolymers were also determined by using an electron spectrometer with Mg Kα X-rays. NMR, and FT-IR spectroscopic, and GPC measurements were employed to characterize and determine the PPG contents (6-43%). From the results, electrospinning process increased the hydrophilic properties of the block copolymers obtained, compared their cast film forms. Our results suggest that these polymers are favorable in biological applications in cases where high ratio of the surface to volume and hydrophilicity are required simultaneously. Both chemical structure and topology of the films are important in wetting and hydrophobicity.     

Synthesis of BN coatings on carbon fiber by dip coating

BN coatings were deposited on carbon fibers by dip coating method. The deposited coatings were characterized by scanning electron microscopy, Fourier‐transformed infrared spectroscopy, X‐ray photoelectron spectroscopy and X‐ray diffraction. The influence of temperature on composition and structure of the coatings was investigated. Composition and structure examinations revealed that the crystallinity of the coatings increased with the increasing temperature, and the coating is a mixture of little oxides, turbostratic boron nitride and hexagonal boron nitride. Furthermore, experiments were also conducted in order to describe the growth mechanism, thus forming the basis of future growth of BN coating on fibers by dip coating. Copyright © 2016 John Wiley & Sons, Ltd.     

辅酶I在Co/CFUE上的电化学行为及应用

辅酶I(NAD )在0.005moL/LTris 0.01moL/LNaCl溶液(pH7.0)中,于钴离子注入修饰碳纤维电极上出现一个S形的还原波,半波电位为-1.45V(vs.SCE)。峰电流与NAD 的浓度在2.38×10-5～4.76×10-4mol/L(r=0 9992)和4.76×10-4～1.78×10-3mol/L(r=0.9982)之间成线性关系,检出限为1.19×10-5mol/L,回收率在96.7%～103.4%之间。用线性扫描、循环伏安法研究了钴离子注入修饰碳纤维电极上NAD 的电化学行为。电极反应机理为:NAD e NAD·;NAD· e H NADH;2NAD·→NAD2。另外,钴离子注入修饰碳纤维电极对NAD 具有电催化作用。     

辅酶Ⅰ在Co／CFUE上的电化学行为及应用

辅酶I(NAD+)在0.005moL/LTris 0.01moL/LNaCl溶液(pH7.0)中,于钴离子注入修饰碳纤维电极上出现一个S形的还原波,半波电位为-1.45V(vs.SCE)。峰电流与NAD+的浓度在2.38×10-5～4.76×10-4mol/L(r=0 9992)和4.76×10-4～1.78×10-3mol/L(r=0.9982)之间成线性关系,检出限为1.19×10-5mol/L,回收率在96.7%～103.4%之间。用线性扫描、循环伏安法研究了钴离子注入修饰碳纤维电极上NAD+的电化学行为。电极反应机理为:NAD++e NAD·;NAD·+e+H+ NADH;2NAD·→NAD2。另外,钴离子注入修饰碳纤维电极对NAD+具有电催化作用。     

Influence of surface properties on the interfacial adhesion in carbon fiber/epoxy composites

A polyacrylonitrile‐based carbon fiber was electrochemically oxidized in an aqueous ammonium bicarbonate solution with current density of up to 2.76 A/m² at room temperature. X‐ray photoelectron spectroscopy revealed that the oxygen content increased with increasing current density before approaching saturation. The increase can be divided into two regions, the rapid increase region (0–1.78 A/m²) and a plateau region (1.78–2.76 A/m²). The surface chemistry analysis showed that the interlaminar shear strength (ILSS) value of the carbon fiber/epoxy composite could be improved by 24.7%. The carbon structure was examined using Raman spectroscopy in terms of order/disorder in the graphite structure and the results indicated that the relative percentage of graphite carbon in the form of sp² hybridization increased above a current density of 1.39 A/m². The increasing non‐polar graphite carbon on the carbon fiber surface decreased the surface energy. As a result, both the surface free energy () and its polar component () decreased when current density increased above 1.78 A/m². The ILSS value had no direct relationship with the nature and surface density of the oxygen‐containing functional groups nor with the carbon structure. It is the surface free energy (), especially the polar component (), which played a critical role in affecting the interfacial adhesion of carbon fiber/epoxy composites. The ILSS value changed with increasing current density and could be divided into three distinct regions, as chemical interaction region (I), anchor force region (II) and matrix damage region (III). Copyright © 2013 John Wiley & Sons, Ltd.     

Anodic square-wave stripping voltammetric analysis of epinephrine using carbon fiber microelectrode

The behavior of epinephrine on a carbon fiber microelectrode (CFME) was studied with cyclic voltammetry and square-wave (SW) stripping voltammetry in order to find optimum conditions for its analysis using the CFME. An anodic stripping peak at about 0.20 V (vs. Ag/AgCl) was utilized. Under optimum conditions for anodic stripping (a pH value of 7.4, a deposition potential of − 0.5 V, a deposition time of 90 s, a final potential of 0.8 V, a SW frequency of 20 Hz, a step potential of 5 mV, and an amplitude of 45 mV), the calibration was linear in the concentration range of 0.0∼0.4 mg/L, and the detection limit was found to be 0.009 mg/L with a relative standard deviation 0.18% (n = 12) at 0.2 mg/L. The analytical performance of the CMFE, which is unmodified, is comparable to or better than other voltammetric results with various modified electrodes.     

Adsorption of Pd, Ni, and Cu ions on anode-oxidized carbon fiber materials

The anodic oxidation of the carbon felt Carbonetcalon results in the formation of surface defects which serve as centers of strong adsorption of Pd^II, Ni^II, and Cu^II ions. The electrochemical reduction of adsorbed ions makes it possible to obtain metallic catalysts, which undergo multiple redox cycles without loss of metal. The catalysts are characterized by high dispersity of the reduced phase, high adsorption capacity with respect to hydrogen, and 100% selectivity in hydrogenation of acetophenone. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 81–85, January 1997     

Effects of clay and surface plasma‐treated carbon fiber on wear behavior of thermoplastic POM composites

In engineering applications, experimental data and insight from scientific investigations on wear properties of polyoxymethylene (POM) composites are important for engineers to understand how to design and formulate POM materials with high resistance to wear. In this work, clay and carbon fiber were utilized and incorporated into POM and the mechanical and wear properties, in specific wear rate, were then assessed. The experimental results suggested that the addition of clay increased the tensile modulus and strength. The mechanical and wear properties of POM composites were found to improve with the addition of the carbon fiber. Carbon fiber/clay/POM composite exhibited the lowest specific wear rate and friction coefficient.