硅油剂及其硅污染

在生产PAN原丝过程中,干燥致密化之前要上油剂,使每根单丝表面形成油膜,防止单丝之间粘连和并丝等。目前,油剂种类主要是硅油剂。但是,硅油剂会带来硅污染,使碳纤维性能下降,这是上硅系油剂的负面影响。如何防止硅污染已提到议事日程,值得关注。本文就硅系油剂及其硅污染做一概述,以引起同仁们的重视。     

喷丝板对干喷湿纺法聚丙烯腈基碳纤维原丝的影响

从堵孔、表面腐蚀、喷丝孔腐蚀等喷丝板质量问题出发,分析了喷丝板对干喷湿纺法聚丙烯腈(PAN)基碳纤维原丝的单丝均一性、原丝及碳纤维的性能影响程度,为提高原丝、碳纤维质量提供一定的硬件设备理论基础。     

碳纤维直径对结构和性能的影响

借助于光学显微镜、扫描电镜和单丝的机械、电性能测试,探讨了PAN原丝直径对预氧丝和碳纤维模截面结构、碳纤维抗张强度、电阻率的影响。结果表明:预氧丝的芯直径随丝的直径增大而增大;粗碳纤维的结构不均匀性比细纤维严重,且在较粗的碳纤维横截面上会出现中空。在一束碳纤维中,随着纤维直径增大,单丝抗张强度下降,电阻率上升。     

硬氧化表面镀层工艺在碳纤维生产设备中的应用

针对聚丙烯腈基碳纤维生产设备中传统硬化工艺铝合金配件存在的不足,采用硬氧化表面镀层工艺对铝合金配件进行表面处理,并从加工成本、使用寿命、配件质量以及对碳纤维原丝质量的影响等方面与传统硬化工艺配件进行比较。结果表明:采用硫酸硬质阳极氧化直流法对碳纤维生产中铝合金原丝托辊和络筒机导丝轮进行表面处理,处理后配件的表面粗糙度及表面硬度与传统硬化工艺配件的基本一致,可满足碳纤维原丝生产要求;硬氧化表面镀层工艺配件的使用寿命相比传统硬化工艺配件得到了很大提高,加工成本也大大降低,可以有效降低碳纤维原丝的生产成本;使用2种镀层工艺配件得到的碳纤维原丝的质量相近;在碳纤维原丝生产中,硬氧化表面镀层工艺配件完全可以替代传统硬化工艺配件。     

两种PAN原丝油剂在碳纤维生产过程中的作用机理探讨

通过比较两种PAN原丝油剂的理化特性,对原丝性能、预氧纤维皮芯结构、碳纤维灰分等进行了分析,探讨了两种油剂在碳纤维生产过程中的作用机理。结果表明,包覆型碳纤维原丝油剂在原丝表面形成一层包覆层并较少的渗透到纤维内部,控制了预氧化阶段氧和能量向纤维内部的径向扩散速率,包覆层在预氧化与低温碳化阶段更容易脱落和排出,减少了纤维缺陷的产生,更好的保护了纤维的皮部结构且使碳纤维的灰分质量分数更低。     

一种聚丙烯腈基中空碳纤维原丝及其制备方法

本发明涉及一种聚丙烯腈基中空碳纤维原丝及其制备方法。本发明的聚丙烯腈基中空碳纤维原丝可用于聚丙烯腈基中空碳纤维的制备。采用含衣康酸的丙烯腈二元共聚体系,或含衣康酸与丙烯酸甲酯的丙烯腈三元共聚体系湿法纺丝工艺配合圆弧狭缝喷丝板纺丝,可以得到多丝束中空碳纤维原丝、该原丝的外径尺寸与结构符合常规预氧化碳化工艺对原丝纤维的要求、纤维表面存在沟槽结构有利于复合材料界面性能的提高。     

澳大利亚推出湿法纺丝生产线将提高碳纤维生产的速度

<正>澳大利亚联邦科学与工业研究组织CSIRO和迪肯大学表示,他们合作推出了一条湿法纺丝生产线,这将可以大大提高碳纤维生产的速度。原丝聚合液经湿法纺丝设备产生五百根单丝纤维并集中成一束在卷筒上收卷,后续在碳化炉中完成碳纤维的制备。CSIRO与迪肯大学的湿纺     

不同线密度粘胶原丝及其碳纤维的结构性能对比

用Weibull分析处理 10mm长的 4种不同线密度粘胶原丝和相应碳纤维的单丝断裂强度 ,得到原丝线密度、强度分布和碳纤维强度的对应关系。采用透射电镜 (TEM )和小角X散射 (SAXS)分析粗旦原丝 ,发现孔洞较多 ,并存在大于 70nm的大孔洞。截面和表面照片也揭示出细旦原丝截面相对规整 ,表面较光滑 ,粗旦原丝则反之。结果表明 ,原丝线密度小 ,截面形状圆整 ,缺陷少 ,所制得的碳纤维强度高。     

蒸汽牵伸对原丝制备及后续碳纤维生产的影响

结合原丝性能、取向度、沸水收缩、以及表面形貌表征,研究了蒸汽牵伸对原丝以及碳化生产状态的影响。结果表明:牵伸提高了原丝的强度和取向度;当牵伸倍数超过4.5时会影响原丝生产,当牵伸倍数超过3.5时会影响后续碳纤维的生产;同时,牵伸倍数受纤维表面油剂覆盖状态的制约。     

PAN原丝至碳纤维缺陷的形成与遗传性

利用扫描电镜（SEM）研究了聚丙烯腈（PAN）原丝至碳纤维结构形态转化过程中缺陷的形成与遗传,结果表明,PAN初生纤维,原丝,预氧化纤维和碳纤维的表面缺陷主要包括沟槽,横纹,粘丝、并丝、杂质、划伤和孔洞等,PAN初生纤维和原丝的内部缺陷主要是皮芯结构、芯部疏松和孔洞,皮芯结构由凝固浴中纤维的双扩散所导致,一直保留到原丝、预氧化纤维直到碳纤维中,可以通过调整凝固的工艺参数增大原丝皮层比例,提高芯部致密性,内部孔洞的形成与扩散和相分离速率有关,可以通过改善致密化和蒸汽拉伸工艺来减少孔洞和减小孔洞尺寸,预氧化纤维中的皮芯结构的形成归因于原丝的遗传和氧的不均匀扩散.     

Friction and wear bahavior of short fiber-reinforced poly(amide-imide) composites

Tribological behavior of short fiber-reinforced thermoplastic composites was investigated experimentally and theoretically. Short carbon fiber and glass fiber reinforced poly(amide-imide) composites were tested. Titanium oxide powder-filled composite was also tested for comparison with the fiber composites. Block-on-ring type wear testing was performed for 24 h at three different sliding conditions. Frictional force was measured and stored by a data acquisition system and wear was measured as weight loss after the test. Wear tracks on the specimen and the counterface were examined with an optical microscope to observe fiber damage and formation of wear film. The equivalent stress distribution around each fiber at the sliding surface was calculated by employing a finite element program. The lowest friction and wear was obtained for the carbon fiber composite, the highest friction for the glass fiber composite, and the highest wear for TiO₂-filled one. It was observed that the glass fibers are damaged and removed from the surface more easily than the carbon fibers, and the finite element analysis also suggests easier debonding of glass fibers.     

Physical and chemical properties of polypyrrole–carbon fiber interphases formed by aqueous electrosynthesis

The properties of carbon fibers modified by aqueous electrochemical synthesis of pyrrole has been determined by using the dynamic contact angle analyzer (DCA), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). Electrochemical process parameters such as the initial pyrrole concentration, electrolyte concentration, applied voltage, electrolyte type, and reaction time were systematically varied, and their impact on the polypyrrole–carbon fiber interphases surface free energy and morphology was ascertained. The surface free energies of the polypyrrole–carbon fiber interphases were obtained by using single fiber filaments. SEM analysis of the interphases revealed several distinct surface structures, including smooth, porous, granular, microspheroidal, and leafoidal morphologies. The noncoated but commercially surface oxidized carbon fibers have smooth surface morphology with occasional longitudinal striations. FTIR analysis of the polypyrrole interphases confirmed that the counterions derived from the electrolytes were incorporated into the film. The surface free energies of the electrochemically formed polypyrrole–carbon fiber interphases equivalent to 60–75 dynes/cm, was determined to be up to 40% higher than that for the surface oxidized but unsized carbon fibers equivalent to 50 dynes/cm. This improvement in the surface free energies of the polypyrrole–carbon fiber interphases suggests easy wettability by polymer matrices such as epoxy resin, γ ˜ 47 dynes/cm and, polyimide matrix, γ ˜ 45 dynes/cm. © 1996 John Wiley & Sons, Inc.     

碳纤维阳极构造对微生物燃料电池性能的影响

微生物燃料电池（MFCs）阳极性能受生物膜的影响,而生物膜则直接与阳极表面积有关。以不同长度和数量的碳纤维丝作为阳极,研究了阳极构造和表面积对MFC输出功率的影响。当阳极为单根长度为1 cm碳纤维丝时,MFC产生的最大功率密度最高,为10.50 W·m^-2,随着碳纤维丝长度逐渐增加（2～14 cm）,MFC产生的最大功率显著下降。以多根的长度为2 cm碳纤维丝构成阳极时,MFC的功率与根数（1～4 根）呈正比,当采用4根2 cm纤维丝时,MFC的最大功率密度为2.92 W·m^-2,该数值为单根8 cm碳纤维丝的2.78倍。观察碳纤维丝长度方向上的生物膜的分布表明：受碳纤维欧姆电阻的影响,在碳纤维丝电流引出端附近的生物量明显大于碳纤维其他地方,这说明：增加纤维丝长度虽可提高阳极的表面积,但并不能提高阳极的产电性能。     

Oxidation of Silicon Carbide Fibers During Static Fatigue in Air at Intermediate Temperatures

The static fatigue of SiC-based fiber bundles and single fibers has been examined in previous papers, with emphasis placed on the analysis of the stress–rupture time data, and on the modelling of delayed failure from slow crack growth. The present paper investigates the oxidation of the fibers during static fatigue, at temperatures in the intermediate temperature range (500°–800°C). Two oxidation-induced phenomena have been evidenced: the formation of a thin silica film at the surface of fibers and the delayed failure of fiber bundles and single filaments. The stress–rupture time data are interpreted with respect to the chemical and structural characteristics of fibers, and to the oxide film growth rate. The structural analysis of the fibers was carried out using scanning electron microscopy and Auger electron spectroscopy. Delayed failure was found to result from slow crack propagation from surface defects, as a result of the consumption of the free carbon at grain boundaries and the local stresses induced by the SiC→SiO₂ transformation at the crack tip. The respective contributions of these phenomena to static fatigue are discussed.     

Tensile strength and morphological investigation of SiC-coated carbon fibers

SiC-coated film onto carbon fibers as a barrier of oxidation resistance and reaction between carbon fibers and metals was investigated. The chemical vapor deposition of silicon carbide onto carbon fibers was performed at various temperatures ranging from 700 to 1000°C using triisopropylsilane vapor carried by hydrogen gas. The strength of the SiC-coated carbon fibers was decreased due to deterioration of fibers and chemical attack of hydrogen on the surface of carbon fibers during the coating process. The oxidation and the thermal resistance of the SiC-coated carbon fibers compared to the uncoated carbon fibers were improved at temperature range of 600–800°C and 1000–1200°C, respectively. Morphological change by air oxidation at temperature range of 500–800‡C was also investigated for the SiC-coated and the uncoated carbon fibers, respectively. The SiC-coated film between carbon fiber and aluminum was sufficient as a barrier of reaction on carbon fiber reinforced aluminum at temperature of above 1000°C.     

碳纳米材料接枝碳纤维的复合材料界面增效研究进展

界面作为复合材料的重要组成部分,起着传递载荷的作用,影响复合材料的整体性能。碳纤维表面属于石墨乱层结构,微晶有序取向,惰性大,不易与树脂基体结合。对碳纤维进行适当的表面改性,增加纤维的比表面积、粗糙度和引入活性官能团,都能改善表面润湿情况,实现机械结合和化学结合,提高复合材料的界面性能。碳纳米材料接枝到碳纤维表面,是提高界面性能的有效方法之一。因此,对碳纳米管、氧化石墨烯接枝碳纤维的制备方法、界面增效设计以及界面增强机制的国内外研究现状进行综述和分析,在此基础上,展望了碳纳米材料接枝碳纤维表面和界面性能评价方法的研究趋势和前景。     

Measurement of Adhesion Between Carbon Fibers and Bismaleimide Resins

The adhesion between carbon fibers and bismaleimide resins was evaluated using the microbond single fiber pull-out test. A commercially-available, methylene dianiline-based bismaleimide resin and a novel phosphorus-containing bismaleimide were tested with as-received and plasma-treated polyacrylonitrile-based carbon fibers. The surface chemical composition, topography, tensile strength, and surface free energy of the carbon fibers were studied using x-ray photoelectron spectroscopy, scanning electron microscopy, single fiber tensile tests, and dynamic contact angle analysis. The carbon fiber-bismaleimide adhesion improved when the carbon fiber received an oxidative commercial surface treatment or was exposed to an air or ammonia plasma prior to bonding.     

Measurement of Adhesion Between Carbon Fibers and Bismaleimide Resins

The adhesion between carbon fibers and bismaleimide resins was evaluated using the microbond single fiber pull-out test. A commercially-available, methylene dianiline-based bismaleimide resin and a novel phosphorus-containing bismaleimide were tested with as-received and plasma-treated polyacrylonitrile-based carbon fibers. The surface chemical composition, topography, tensile strength, and surface free energy of the carbon fibers were studied using x-ray photoelectron spectroscopy, scanning electron microscopy, single fiber tensile tests, and dynamic contact angle analysis. The carbon fiber-bismaleimide adhesion improved when the carbon fiber received an oxidative commercial surface treatment or was exposed to an air or ammonia plasma prior to bonding.     

高温热处理后炭纤维表面微观形态

炭纤维的表面微观形态对其力学性能有很大影响，选择国产和日本东邦公司的炭纤维，对其进行高温热处理（1800～2500℃），研究了热处理温度对炭纤维力学性能、密度的影响。用SEM观察了热处理前后炭纤维的表面微观形态变化，讨论了表面缺陷产生的原因。     

The Effect of Surface Activation in Polymer Matrix-Carbon Fiber Interactions

Various carbon fibers (CF) were surface modified by chemical and electrochemical treatments for the purpose of establishing organic functional groups on the fiber surface. A series of fibers, surface oxidized for various periods of time, was prepared. The amounts of surface functionalities formed were assessed by means of contact angle measurements on single fibers. A suitable set of probe liquids was used to determine the LW (Lifshitz-van der Waals) and acid-base components of carbon fiber surfaces. Similar tests were made on commercial, sized carbon fibers, polystyrene (PS) and polymethyl methacrylate (PMMA), and their surface energies determined in terms of LW, surface acidity and surface basicity components. Work of adhesion values were calculated of all combinations of CF and polymer matrix couples by using these surface energies of both constituents. The calculated work of adhesion values were correlated to the ILSS values obtained from single fiber pull out tests with PS and PMMA as matrices.