基于熔融纺丝PAN原丝的数值模拟研究

采用熔融纺丝制备聚丙烯腈(PAN)基碳纤维原丝,根据聚合物熔融纺丝的基本原理,选取PhanThien-Tanner微分粘弹模型,利用Polyflow软件对PAN熔融纺丝过程进行数值模拟,研究了PAN原丝制备过程的直径变化、拉伸速率分布、温度分布规律。结果表明:在距喷丝板0~10 cm处纤维直径急剧缩小,10~20 cm处开始缓慢减小,之后趋于稳定,纤维表面和纤维中心拉伸速率几乎重合,纤维中心温度一直高于表面温度,在离喷丝板2~15 cm处,纤维中心温度与表面温度之差较大,之后温差变小最终趋于0℃;数值仿真模拟可以较准确地模拟PAN熔融纺丝过程;熔融纺丝制得PAN原丝,其断裂强度能满足高性能碳纤维原丝的强度要求。     

PAN原丝直径对碳纤维收率的影响

对不同预氧化条件下两种直径PAN原丝的碳纤维收率进行了分析,并利用TG、XPS、NMR、Raman等测试表征方法,深入讨论了原丝直径对其碳纤维收率的影响。结果表明:预氧化温度越高,PAN原丝的碳纤维收率越高,相同工艺条件下粗直径PAN原丝的碳纤维收率高于细直径原丝的碳纤维收率,粗直径PAN原丝的热失重一直低于细直径原丝的热失重,细直径PAN预氧丝的预氧化程度高于粗直径PAN原丝的预氧化程度,而不同直径预氧丝表面元素及碳纤维表面微晶结构无差异。     

水洗方法对PAN原丝及其碳纤维结构与性能的影响

在聚丙烯腈(PAN)基碳纤维生产中,分别采用浸涌式水洗、拍打式水洗、超声式水洗3种方法对PAN原丝进行水洗,讨论了PAN原丝的线密度对水洗效果的影响,以及3种水洗方法对PAN原丝及其碳纤维的结构与性能的影响。结果表明:在水洗流量1 m3/h、水洗温度60℃、水洗时间1.2 min的条件下,随着PAN原丝线密度的增加,原丝中二甲基亚砜(DMSO)残留量增加,浸涌式水洗受原丝线密度的影响较大,超声式水洗受原丝线密度的影响较小;在PAN原丝线密度为4.0 dtex时,PAN原丝经浸涌式、拍打式、超声式水洗后,DMSO残留量分别为1 000,200,90μg/g,相应碳纤维强度分别为5 139,5 120,4 930 MPa;浸涌式水洗对PAN纤维的损伤较小,超声式水洗对PAN纤维的损伤较大。     

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.     

聚丙烯腈纤维制备碳纤维的研究—X射线衍射法的应用

本文综述了利用广角X射线衍射分析研究聚丙烯腈(PAN)纤维制备碳纤维的预氧稳定化过程。X射线衍射法在表征PAN原丝纤维序态结构、玻璃化转变及PAN纤维在预氧化阶段的环化动力学方面已获得了广泛的应用。     

聚丙烯腈纤维在预氧化过程中的分子运动

本文主要叙述用动态力学试验方法研究碳纤维原丝(PAN纤维)在不同温度的连续预氧化处理中的动态力学性能、结构及热变形行为的相关性,为制备优质的碳纤维提供依据。     

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。     

不同工艺制备的聚丙烯腈纤维的耐碱特性研究

模拟水泥混凝土的施工条件,试验测定了3种不同工艺制备的聚丙烯腈(PAN)纤维在碱性条件下的结构和性能变化。红外光谱(FT-IR)测试结果表明,在碱性介质的作用下PAN纤维发生一定程度的水解,广角X-射线散射(WAXS)分析表明,在碱性条件下PAN纤维的结晶度、晶粒尺寸、晶区取向因子均出现一定程度的下降。其中以碳纤维原丝生产工艺(PAN-1)制备的聚丙烯腈纤维分子质量最高,共聚单体含量最低,结晶度、取向度最高,耐碱腐蚀能力最好,强力保持率明显高于常规干法纺丝(PAN-2)和常规湿法纺丝(PAN-3)制备的PAN纤维,有潜力作为水泥混凝土防裂增强材料使用。     

聚丙烯腈原丝及其干喷湿纺

介绍了用于 PAN基碳纤维的聚丙烯腈原丝的发展历史 ,阐述了聚丙烯腈纺丝工艺中的主要工序和技术关键 ,指出了可以在聚合、纺丝过程中通过控制杂质及使用高相对分子质量的 PAN树脂纺制 PAN纤维等方法来提高原丝的性能。着重介绍了目前纺丝工艺中 PAN共聚体的制备、纺丝流体的流变行为及其凝固过程等重要工序的研究成果     

NTT碳纤维集团公司宣布Koreox预氧化PAN纤维新产品系列

Koreox预氧化PAN纤维是一种阻燃性纤维,由轻度碳化的碳纤维聚丙烯腈原丝制造。当它在更高温度下经过进一步碳化,预氧化PAN纤维转变成碳纤维。当它进行蒸发或化学活性过程,成为一种具有活性的碳纤维。这就证明Koreox预氧化PAN纤维属于丙烯酸碳纤维族,是一种先进功能纤维,且持有高度阻燃性。     

聚丙烯腈原丝性能研究

聚丙烯腈（ＰＡＮ）原丝质量已经成为阻碍我国炭纤维（ＣＦ）工业发展的重要因素之一。利用Ｘ射线衍射等手段测定了３种ＰＡＮ原丝的性能,并进行了对比分析。结果表明,英国原丝的性能如强度、模量、直径及离散性等均优于国产原丝。共聚组分和微观结构的差异是导致此结果的主要因素。     

腈纶生产的回顾与发展建议

对世界腈纶工业的发展及其趋势作了简要的回顾与分析。介绍了中国腈纶工业现状，对五种可能在国内发展的工艺路线作了比较，并对我国腈纶发展提出了建议。     

Effect of blend composition on the morphology development of electrospun fibres based on PAN/PMMA blends

BACKGROUND: The aim of the work presented was to determine the morphology development and relevant change in fibre diameter of a binary polymer blend system during an electrospinning process. The size of the fibre diameter is one of the important factors determining the general properties of non‐woven mats formed from electrospun fibres. RESULTS: The morphology and diameter of electrospun polyacrylonitrile (PAN)/poly(methyl methacrylate) (PMMA) blends were investigated as a function of blend ratio using scanning electron microscopy. The diameter of the electrospun PAN/PMMA fibres decreased with increasing PMMA content up to 50 wt%, and then increased again with further increase of PMMA. After thermal treatment, the fibres shrank, and an irregularly shaped morphology was observed. CONCLUSION: The electrospinning of incompatible PAN/PMMA blends leads to a microphase‐separation morphology of fibres. A phase inversion occurs at a PMMA content of between 50 and 75 wt%. Due to the phase inversion, the fibre diameter shows a minimum value at the relevant composition. Copyright © 2008 Society of Chemical Industry     

Improvement of Manufacturing Technology for Ultrastrong and High-Modulus Carbon Fibres

1. The quality of CF, their strength and modulus of elasticity in particular, can be increased by the following methods: reducing the porosity of the initial PAN fibres by selecting the optimum conditions for spinning, plasticization drawing, finishing, and drying; decreasing the nonuniformity of the fibre diameter due to suppression of deformation resonance during spinning by selecting the jet formation and hardening conditions; decreasing the fibril and crystallite size by reducing the precipitator and solvent concentration gradient in the precipitation zone (spinning into mild baths); creating optimum conditions for mesophase self-ordering of the material at 450–550° C during precarbonization; increasing the cohesive energy by increasing the density to 1.8–2.1 g/cm³. 2. Replacing convective tempering of PAN twists in thermooxidative treatment by conductive tempering reduces the treatment time by 3–4 times. __________ Translated from Khimicheskie Volokna, No. 5, pp. 11–15, September–October, 2005.     

炭黑添加剂对PAN原丝性能的影响

用炭黑改性聚丙烯腈原丝制得了中孔率大大提高的活性炭纤维。考察了炭黑对聚丙烯腈——二甲基亚砜纺丝溶液粘度、可纺位及纺得纤维微观结构、元素组成、力学性能和热性能的影响。由于炭黑具有纳米级的位径和粗糙的表面，因此可均匀分散于聚丙烯腈溶液及纤维中并与聚丙烯腈大分子结合，使其溶液粘度，粘流活化能增大。结晶度减小，但对其热性能影响不大。     

A study of spalling behaviour of PAN fibre-reinforced concrete by thermal analysis

Comparisons are made between polypropylene (PP) fibres and polyacrylonitrile (PAN) fibres in order to relate the thermal properties of fibres with the respective fibre mortar behaviour under thermal exposure. Thermogravimetry (TG), differential scanning calorimetry (DSC) and thermochromatography (ThGC) are utilized. When a cementitious fibre mortar is being heated, several physical phenomena occur in the temperature range between 100°C and 200°C. There is a significant difference in the thermal behaviour between PP and PAN fibres. PP fibres melt at 160–170°C. The non-melting behaviour of PAN fibre together with its rapid exothermic degradation reactions at around 300°C may add risk to the spalling of fibre mortar under rapid thermal exposure.     

Carbon Fibres with Specific Physical and Physicochemical Properties Based on Hydrated Cellulose and Polyacrylonitrile Precursors. A Review

A wide assortment of carbon fibres (CF) made from readily available hydrated cellulose (HC) and PAN staple fibres and twists, textile and other fibre materials, including heat and chemical-resistant composites, has been developed. The use of these materials is based on their unique thermal, physical, physicochemical, and biological properties. The precursor fibres have their own characteristics and the properties of the CF and CFM made from them are correspondingly different. The economic aspects of their fabrication differ slightly, and CF made from PAN perhaps now have some advantages. However, in the near future, the price ratio will vary in support of cellulose fibres since products made from crude oil, natural gas, and coal are gradually becoming more expensive. The economics of small-tonnage fibres with original specific properties should be taken into consideration based on the efficiency of their use. The uniqueness of these fibres gives those which are irreplaceable and most effective the right to life. In this respect, all of the CF and CFM examined are important and promising. Far from all of the possible applications of these fibres have been discovered and implemented, which makes them even more promising for the future.     

Pressure drops along the bores of hollow fibre membranes—their measurement,prediction and effect on fibre bundle performance

Measurements of the pressure drops along the bores of hollow fibres in a B9 fibre bundle have been made under operating conditions. A theoretical model of the fibre behaviour is presented and analysed. An analytical solution is obtained for the case of a fibre in a uniform crossflow of brine of uniform concentration and uniform pressure. A numerical procedure, making use of this analytical solution, is developed to solve the more general problem of detailed bundle behaviour. This procedure takes into account the variation of brine concentration along fibre lengths and the fact that in some cases the product concentration can be significant. Sets of experimental data, including the measurements of bore pressures, are presented and analysed using a computer program based on the numerical procedure presented. Evidence of compression of the fibre bore diameter due to the external brine pressure is found, particularly at higher temperatures and pressures.     

Thermooxidative stability of carbon fibres and methods of increasing it

It is necessary to introduce an additional stage of elimination of sodium ions to obtain carbon fibre with elevated thermooxidative stability based on PAN fibre by the water—thiocyanate spinning method. This can be done in different stages of the technological process of fabrication of CF. CF fabricated from PAN with sodium impurities washed off by the water—thiocyanate spinning method has thermooxidative stability close to CF fabricated from PAN by the dimethylformamide method. Several ways of eliminating sodium ions are reported, but their actual implementation will probably be a function of the economy and technical expediency of each one.All-Russian Scientific-Research Institute of Polymer Fibres, Mytishchi. Translated from Khimicheskie Volokna, No. 2, pp. 27–28, March–April, 1995.