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.     

高端工业应用驱动国内碳纤维迎来发展新机遇

碳纤维生产流程分析：生产流程长,技术壁垒高。PAN基碳纤维生产流程包括丙烯腈聚合形成PAN纺丝液、PAN原丝的制备、PAN原丝的预氧化工艺、PAN原丝低温碳化及高温碳化工艺、表面处理形成碳纤维产品、与树脂等形成复合材料及最终的工业、军用等产品。工艺流程长,核心关键技术多,实现工业化生产技术壁垒高,并还有很强规模效应。目前国内制造企业与国外龙头企业还存在的不小的差距。     

热解沉积结合PAMAM接枝改性碳纤维表面

采用热解沉积结合聚酰胺-胺型树枝状高分子(PAMAM)接枝的改性方式对碳纤维进行表面处理,对比了碳纤维原丝(CFs)、只经热解沉积处理碳纤维(PD-CFs)和沉积结合接枝处理碳纤维(PD-PG-CFs)的表面形貌、表面元素组成和质量分数、与极性液体和非极性液体的接触角、表面自由能的变化;制备了不同处理条件下碳纤维/环氧微复合材料,与未处理的碳纤维原丝相比,经热解沉积处理的碳纤维/环氧复合材料的界面剪切强度(IFSS)提高了26.87%,而经沉积结合PAMAM接枝处理碳纤维/环氧复合材料的IFSS则提高了38.81%。通过纳米压痕测试定量的表征了复合材料中碳纤维、热解碳层和树脂基体3者的模量,结果表明,热解碳层的模量介于碳纤维和树脂之间,它所起到的过渡层效应是复合材料界面性能得到改善的重要原因。     

PAN基碳纤维原丝表面形态控制研究

采用扫描电子显微镜(SEM)表征PAN原丝表面沟槽形态,通过凝固浴φ(二甲基亚砜)、温度、pH值、负牵伸倍数的变化对PAN原丝的表面沟槽形态进行控制。结果表明在一定范围内凝固浴φ(二甲基亚砜)的提高、凝固浴温度的降低、凝固浴pH值的提高、凝固浴负牵伸倍数的增加都有利于制备表面沟槽更深的PAN原丝。碳纤维表面沟槽一方面对纤维表面造成一定的机械损伤,另一方面可以提高碳纤维的界面结合力,所以适宜的表面沟槽才能使碳纤维的力学性能得以充分发挥。     

成都拟建年产5000吨高性能碳纤维项目

四川省华拓实业发展股份有限公司在成都市双流县拟建PAN树脂合成、PAN原丝、预氧化、碳化、碳纤维处理等五个车间．二条PAN原丝,三条碳纤维（CARBONFIBER）的生产线,形成年产PAN原丝10000吨,碳纤维4000吨,石墨碳纤维1000吨的生产能力。投资总额12．0506亿元。     

超高强度PAN基碳纤维的研制技术

本文从聚丙烯腈原丝的制备,PAN纤维的预氧化,碳化工艺以及碳纤维的表面处理三个方面综述了近年来国外超高强度PAN基碳纤维的研制方法,指出,碳纤维抗张强度的大幅度提高主要来源于高质量的PAN原丝,同时,PAN纤维的预氧化和碳化工艺的改进以及碳纤维表面处理也能较为有效地提高碳纤维的抗张强度。     

PAN基碳纤维增强复合材料生产工艺及应用

阐述了PAN原丝生产工艺，碳纤维成形工艺及纤维表面处理，同时介绍了碳纤维复合材料的成型工艺及其应用。     

四川年产5000吨高性能碳纤维产业化项目

四川省华拓实业发展股份有限公司购置主要设备366台套,其中进口设备为235台套,拟建PAN树脂合成、PAN原丝、预氧化、碳化、碳纤维处理等五个车间,二条PAN原丝,三条碳纤维（CARBON-FIBER）的生产线,形成年产PAN原丝10000吨,碳纤维4000吨。石墨碳纤维1000吨的生产能力。投资总额120506万元,建设地点在成都市双流县。     

碳纤维表面电化学氧化的研究

主要采用电化学氧化法对聚丙烯腈(PAN)基碳纤维进行连续氧化处理,利用扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和动态力学热分析(DMTA)对碳纤维表面处理效果进行了研究。SEM表面形貌研究结果表明,碳纤维经电化学氧化处理后,其表面的粗糙度和比表面积增大。XPS表面化学分析表明,经电化学氧化处理后的碳纤维表面羟基含量提高55％,活性碳原子数增加18％。DMTA谱图表明经电化学氧化处理的碳纤维增强树脂基复合材料(CFRP)其玻璃化温度(Tg)提高5℃、损耗角正切(tanδ)较未处理的降低30％。定量计算出的界面黏结参数A和α与CHRP的层间剪切强度(ILSS)所反映的碳纤维与树脂间界面黏结效果是一致的。研究结果表明,采用适当的处理条件可使CFRP的ILSS提高20％以上。     

聚丙烯腈基碳纤维灰分的来源及其影响因素

研究了聚丙烯腈(PAN)原丝及PAN基碳纤维灰分的形态结构及化学成分,分析了碳纤维灰分产生的原因及其影响因素。结果表明:PAN原丝灰分及碳纤维灰分主要由C、O及Si三种元素组成,并且Si元素为灰分的主体成分;原丝灰分与碳纤维灰分之间存在线性关系;油剂种类及上油率是影响原丝及碳纤维灰分含量的主要因素;油剂中硅含量高,上油率高均会导致原丝及碳纤维灰分的大幅提高。     

Multiwalled carbon nanotube/polyacrylonitrile composite fibers prepared by in situ polymerization

Multi‐walled carbon nanotubes (CNTs) were mixed with polyacrylonitrile (PAN) by in situ polymerization or by mechanically mixing. The mixtures were then wet‐spun into fibers, respectively. The effects of mixing method on the interfacial bonding between the components in the fibers and the properties of the fiber were investigated by Raman spectroscopy, TEM, SEM, and tensile strength testing. By in situ polymerization mixing, a thin layer of PAN molecules is observed to cover the surface of the CNT, which increases the diameter of CNT evidently. Results of Raman spectroscopy indicate that the layer of PAN molecules are strongly attached onto the surface of CNT through grafting polymerization, leading to strong chemical bonding between CNTs and PAN matrix in the obtained fibers. In contrast, no obvious chemical interactions are observed between them in the fibers prepared by mechanically mixing. In both cases, the CNTs have significantly strengthened the PAN fibers. However, the fibers prepared from in situ polymerization mixing are much stronger because of the interfacial bonding effect between the PAN molecules and CNTs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Electrical conductivity and oxygen permeability of polyacrylonitrile/multiwalled carbon nanotubes composites

Polyacrylonitrile (PAN)/Multiwalled carbon nanotube (MWCNT) nanocomposites were prepared by nonconventional ultrasonic‐assisted emulsifier free emulsion polymerization technique with variable percentage of functionalized carbon nanotube. PAN/MWCNT nanocomposites were characterized by ultraviolet‐visible (UV‐visible) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The result from UV‐visible suggested that the functionalized MWCNT had interfacial interaction with PAN matrices. The surface morphology of functionalized MWCNT and PAN/MWCNT nanocomposites were studied by scanning electron microscopy (SEM). Electrical properties of PAN/MWCNT nanocomposites were measured and the result indicated that the conductivity increased with increasing concentration of MWCNTs. The oxygen permeability of PAN/MWCNT nanocomposites gradually increased with increase of MWCNT concentration, the result which was in agreement with the vertical alignment ofMWCNT in SEM. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Effect of surface oxygen content and roughness on interfacial adhesion in carbon fiber–polycarbonate composites

The effect of surface chemistry and rugosity on the interfacial adhesion between Bisphenol-A Polycarbonate and a carbon fiber surface subjected to surface treatment to add surface oxygen groups was investigated. The surface oxygen content of PAN based intermediate modulus IM7 carbon fibers was varied by an oxidative surface treatment. The oxygen content of the carbon fiber surface increased from 4 to 22% by changing the degree of surface treatment from 0 to 400% of nominal commercial surface treatment levels. The oxidative surface treatment also causes an increase in surface roughness by creating pores and fissures in the surface by removing carbon from the regions between the graphite crystallites. To decouple the effects of surface roughness and the surface oxides on the interfacial adhesion, the oxidized fiber surface was passivated via hydrogenation at elevated temperature. Thermal hydrogenation removes the oxides on the surface without significantly altering the surface topography. The results of interfacial adhesion tests indicate that an increase in the oxygen content of the fiber does not increase the fiber-matrix interfacial adhesion significantly. Comparing adhesion results between oxidized and hydrogen passivated fibers shows that the effect of the surface roughness on the interfacial adhesion is also insignificant. Overall, dispersive interactions alone appear to be the primary factor in adhesion of carbon fibers to thermoplastic matrices in composites.     

Morphological aspects of the interface in the PEEK-carbon fiber system

Although high modulus PAN based carbon fibers (HMS) induce transcrystallinity in PEEK and a wide variety of other semi-crystalline polymers, the interfacial strength is lower than PEEK in contact with low modulus carbon fibers (AS4) where transcrystallinity is not induced. In the PEEK/HMS system, crystalline lamellae were found to be oriented edge-on to the fibers, while in AS4 they were oriented flat-on, reflecting the difference in surface energies between the two fibers. The intrinsic effect of transcrystallinity on the fiber matrix interaction is therefore obscured when the chemistry of the interaction varies.     

大豆蛋白/聚丙烯腈共混纤维结构性能研究

研究了以二甲基亚砜为溶剂,经湿法纺丝所制备的大豆蛋白/聚丙烯腈共混纤维的结构性能。红外光谱分析表明:共混纤维主要组成为聚丙烯腈和大豆蛋白质;扫描电镜观察发现:纤维的表面有凸起颗粒及较深的沟槽;共混纤维的断裂强度略有降低,断裂伸长率基本不变;纤维的表面接触角及回潮率的测试表明:共混纤维的吸湿性得到提高。     

Improvement of interfacial properties in bismaleimide composites using functionalized graphene oxide grafted carbon fiber

A hierarchical reinforcement, which was used to improve the interfacial properties of bismaleimide (BMI) composites, was prepared by grafting functionalized graphene oxide (GO) onto a carbon fiber surface. The GO and carbon fibers were first functionalized separately to create interactional functional groups on their surfaces. The grafting process was then realized by an amidation reaction of the amine and acyl chloride function groups formed on GO and carbon fibers, respectively. The surface groups of functionalized GO and carbon fibers were identified by an X‐ray photoelectron spectroscopy (XPS). The resulting reinforcement was further characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and dynamic contact angle analysis. Experimental results showed that the functionalized GO were successfully grafted onto the carbon fibers surfaces and significantly increased the surface energy of carbon fibers. The study also indicated that the prepared hierarchical reinforcement could significantly improve the interfacial adhesion of resulting BMI composite. POLYM. ENG. SCI., 58:886–893, 2018. © 2017 Society of Plastics Engineers     

Effect of activation on boron nitride coating on carbon fiber

Boron nitride (BN) thin coating has been formed on the surface of chemically activated polyacrylonitrile (PAN) carbon fibers by dip coating method. The chemical activation of PAN fibers was carried out by two different chemicals, i.e. nitric acid (HNO₃) and silver nitrate (AgNO₃) solution. The chemical activation changes the surface properties, e.g. surface area and surface microstructure of the carbon fibers. These surface modifications ultimately influence properties of boron nitride coating on carbon fibers. The boron nitride coating on carbon fibers showed better crystallinity, strength and oxidation resistance when carbon fibers were activated by HNO₃. This improvement in strength and oxidation resistance is attributed to better crystallinity of boron nitride coating on HNO₃ activated PAN fibers.     

聚丙烯腈基碳纤维的制备工艺过程和纤维结构研究

采用丙烯腈（AN）与丙烯酸（AA）自由基溶液共聚合,以偶氮二异丁腈（AIBN）为引发剂,在二甲基亚砜（DMSO）中合成了聚丙烯腈纺丝溶液,经湿法纺丝制得聚丙烯腈（PAN）原丝、经过热稳定化和炭化得到聚丙烯腈基碳纤维,拉伸强度达到3．2GPa,杨氏模量为236GPa。采用扫描,透射电镜对纤维的结构进行表征。     

Reactivity and related microstructure of 3d carbon/carbon composites

Four carbon/carbon composites fabricated with either PAN fibers or coal tar pitch fibers were examined. Detailed analysis of composite properties and structure included total surface area by Kr adsorption at 77 K, active surface area, porosity, crystallite parameters, as well as SEM and optical microscopic observations. Rates of composite gasification were measured at 1123 K in 3.1 kPa of steam. Under these experimental conditions the composites fabricated with PAN fibers are roughly three times as reactive as those fabricated with pitch fibers. Microscopic examination of the composites provides detail on two different microstructures for each fiber and respective composite. Binder associated with the fibers is influenced by the fiber microstructure, and a continuation of structure is developed throughout the composite body. Even though the fiber fraction is only approximately 50% of the composite by weight, it is clear that fiber microstructure influences overall composite microstructure and, hence, composite physical properties and subsequent composite gasification behavior.     

The influence of pyrolysis on physical properties and microstructure of modified PAN fibers during carbonization

Modification of polyacrylonitrile (PAN) fibers with potassium permanganate has reduced the time required for stabilization and also improved the mechanical properties of the resulting carbon fibers. In this study, the effect of modification on the physical properties, microstructure, and elemental composition of fibers during the carbonization process was examined for the first time. The resulting carbon fibers developed from modified PAN fibers had a higher density, a greater stacking size (Lc), and a higher preferred orientation than those developed from unmodified PAN fibers. The carbon fibers developed from the modified PAN fibers also showed an improvement in tensile strength from 20 to 40%. These fibers showed a radial structure in the fracture surface and were somewhat different structurally in the cross section than were the carbon fibers developed from the original PAN fibers. A model for the structure of both carbon fibers is presented. The relationship between the formation of closed pores from open pores and the variety of cumulative pore area during the heat-treatment stage is also discussed.