聚丙烯腈基碳纤维的研究进展

综述了聚丙烯腈(PAN)基碳纤维制备技术现状和进展.分析了对PAN原丝质最有重要影响的PAN化学组成、纺丝溶剂和纺丝技术特点.重点讨论了PAN原丝氧化稳定工艺和机理、碳化过程所发生的化学反应和工艺过程以及石墨化对碳纤维性能的影响.在分析国外碳纤维研究进展的基础上,建议应重点完善PAN原丝生产工艺,利用国内外最新研究成果,采用有效的试验方法,将碳纤维的抗拉强度和杨氏模量作为目标函数,建立各种工艺条件对目标函数影响的数学模型,判别对碳纤维性能有重要影响的参数,并寻找出高性能碳纤维生产较为理想的工艺条件.     

静电纺丝制备聚丙烯腈纳米碳纤维

利用静电纺丝制备连续的聚丙烯腈纳米碳纤维;介绍了静电纺丝的原理、影响静电纺丝的主要因素以及制备纳米碳纤维、纳米活性炭纤维、纳米碳纤维复合材料的方法和原理;分析了静电纺丝产率低,难以得到单向平铺的纤维等问题,影响静电纺丝的参数主要有溶液特性、纺丝工艺参数、纺丝环境参数。由静电纺丝得到纳米聚丙烯腈纤维,然后再经预氧化和碳化制备纳米碳纤维,或把纳米纤维预氧化,经活化、碳化制备纳米活性炭纤维。并指出纳米碳纤维具有巨大的潜在应用空间。     

关于我国碳纤维用聚丙烯腈原丝质量的若干认识

分析了我国碳纤维用聚丙烯腈原丝质量欠佳的原因,主要是生产工艺包括聚丙烯腈的聚合方法、聚合物相对分子质量及其分散性、纺丝原液的纯度及其流变性、纺丝方法以及拉伸工艺等存在弊端。指出我国碳纤维用聚丙烯腈原丝生产过程中,应加强对聚合物及纺丝原液的质量控制,开发干-湿法工艺,从而提高原丝质量。     

通用型沥青基炭纤维纺丝工艺的优化研究

以软化点为294℃、喹啉不溶物为28.35%的各向同性沥青为原料,以通用型沥青基炭纤维的丝径与抗拉强度为评价指标,选择原丝制备过程中的纺丝温度、纺丝压力和拉伸速率工艺参数,运用三元二次回归正交设计对纺丝工艺进行优化组合,探究了最佳的纺丝工艺条件。研究结果表明,纺丝温度及纺丝压力对炭纤维丝径与抗拉强度的显著性影响大于拉伸速率的显著性影响。在纺丝温度为383℃、纺丝压力为0.26 MPa、拉伸速率为319 m/min的条件下进行熔融纺丝,将纺制的原丝经过预氧化和炭化处理后,获得的炭纤维丝径为15.6μm,其抗拉强度达到631 MPa。     

中介相沥青液晶熔体纺丝

阐述了中介相沥青液晶熔体纺丝工艺条件及其对碳纤维结构与性能的影响，讨论了单孔纺丝中各种纺丝工艺条件与纺丝稳定性的关系，介绍了几种新型纺丝方法如多孔纺丝、异形纺丝、复合纺丝、离心纺丝和熔吹纺丝，简要介绍了获得带形、Ｙ字形、三角形、中空形和线圈状碳纤维的制备工艺，最后指出使用狭缝形喷丝孔易于获得模量高达９３０ＧＰａ的超高模量碳纤维。     

煤加氢热解沥青制备通用级沥青碳纤维的研究

以煤加氢热解沥青为原料,采用空气氧化和氮气吹扫处理,制备了可纺沥青,收率超过70％。可纺沥青经过纺丝、预氧化和炭化,制得通用级沥青碳纤维。实验结果表明,沥青碳纤维直径12．2um、抗拉强度623MPa、模量30．5GPa、伸长率2．05％。     

用煤焦油沥青制炭纤维

煤焦油沥青为生产碳纤维提供了数量充足、碳收率高、又相当廉价的一种原料。本文叙述了从煤焦油沥青制造碳纤维的制备过程。通过诸如煤的低温碳化或焦化等不同的方法,制出了煤焦油沥青,并研究了它们对熔融纺丝工艺的适合性。与碳纤维的常规制法不同,本工艺包含了一项极短时间的氧化处理。     

增材制造连续碳纤维增强金属基复合材料性能

采用增材制造工艺方法进行具有高比强度、密度小等优良性能连续碳纤维增强金属基复合材料的直接制备。研究了连续碳纤维表面改性、路径搭接率、打印喷头温度、基板温度、打印速度等过程处理方法及工艺参数对所制备金属基复合材料抗拉强度的影响。研究结果表明,对连续碳纤维原材料实施表面改性处理,可以实现制备过程中熔融金属基体与连续碳纤维之间的良好浸润复合,以提高复合材料的抗拉强度;增大路径搭接率,可以有效提高增材制造复合材料内部纤维的体积占比,从而增大其抗拉强度;升高打印喷头温度、基板温度、打印速度,可以减小熔融金属表面张力,提高其流动性,并有利于沉积层间实现良好重熔,从而有效避免在已沉积层表面裂纹处和路径搭接区凹坑处形成气孔缺陷,进一步提升复合材料的抗拉强度。     

高抗拉强度和高弹性模量碳纤维

Teijin公司通过精心选择沥青基质和改进纺丝技术生产出均质的碳纤维,它是适用于生产航空部件的沥青基碳纤维。这种碳纤维抗拉强度500kgf/cm~2;弹性模量25000kg/mm~2。     

熔融纺丝工艺制备碳纤维原丝

聚丙烯腈基碳纤维的制备主要采用溶液纺丝方法,生产过程需要溶剂回收,工艺流程长,因此制造成本高。笔者主要介绍了聚丙烯腈基碳纤维的制备工艺概况,特别介绍了熔融纺丝路线制备聚丙烯腈原丝的方法。利用共聚改性、增塑改性、纺丝后处理等方法,可以制备聚丙烯腈基碳纤维,并提出了由熔融纺丝制备聚丙烯腈基碳纤维的可行路线。     

加捻对T800碳纤维拉伸性能的影响

要通过对日本东丽1700、T800碳纤维复丝拉伸性能的表征主要研究了加捻对,T800碳纤维拉伸性能的影响。研究结果表明：采用浸胶后加捻的方式有助于改善T800碳纤维的拉伸性能,合适的捻度可使其拉伸强度提高5％,断裂延伸率提高10％。并通过对rr800碳纤维干纱加捻的研究基本确定了T800碳纤维的临界捻度为15n／m。     

Lignin-based carbon fibers for composite fiber applications

Carbon fibers have been produced for the first time from a commercially available kraft lignin, without any chemical modification, by thermal spinning followed by carbonization. A fusible lignin with excellent spinnability to form a fine filament was produced with a thermal pretreatment under vacuum. Blending the lignin with poly(ethylene oxide) (PEO) further facilitated fiber spinning, but at PEO levels greater than 5%, the blends could not be stabilized without the individual fibers fusing together. Carbon fibers produced had an over-all yield of 45%. The tensile strength and modulus increased with decreasing fiber diameter, and are comparable to those of much smaller diameter carbon fibers produced from phenolated exploded lignins. In view of the mechanical properties, tensile 400–550 MPa and modulus 30–60 GPa, kraft lignin should be further investigated as a precursor for general grade carbon fibers.     

Improving the tensile strength of carbon nanotube spun yarns using a modified spinning process

A modified process for the dry spinning of carbon nanotube (CNT) yarn is reported. The approach gives an improved structure of CNT bundles in the web drawn from the CNT forest and in the yarn produced from the twisted web leading to improved mechanical properties of the yarn. The process enables many different mechanical and physical treatments to be applied to the individual stages of the pure CNT spinning system, and may allow potential for the development of complex spinning processes such as polymer-CNT-based composite yarns. The tensile strength and yarn/web structure of yarn spun using this approach have been investigated and evaluated using standard tensile testing methods along with scanning electron microscopy. The experimental results show that the tensile properties were significantly improved. The effect of heat treatments and other yarn constructions on the tensile properties are also reported.     

Process–structure–property relationship of melt spun poly(lactic acid) fibers produced in the spunbond process

We report on the process–structure–property relationships for Poly(lactic acid) (PLA) filaments produced through the spunbond process. The influence of spinning speed, polymer throughput, and draw ratio on crystallinity and birefringence of fibers were evaluated. We established that increasing spinning speed increases crystallinity and birefringence of fibers. We also investigate the role of fiber structures on fiber tensile properties—breaking tensile strength, strain at break, initial modulus, and natural draw ratio. An increase in spinning speed leads to a higher breaking tensile strength, higher initial modulus and lower strain at break. We have shown an almost linear relationship between breaking tensile strength of PLA fibers and birefringence. This indicates that improved tensile properties at high spinning speeds can be attributed to enhanced molecular orientation. The dependency of fiber breaking tensile strength and strain at break on spun orientation were explained with natural draw ratio, as a measure of spun orientation. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44225.     

Spinnability of low‐substituted hydroxyethylcellulose sodium hydroxide aqueous solutions

Ethylene oxide was used to etherify alkali cellulose with a low substitution degree to replace carbon disulfide to generate cellulose xanthogenate by viscose technology. The resultant low‐substituted hydroxyethylcellulose (LSHEC), with molar substitution of 0.49, was used to attempt to spin LSHEC fibers under spinning and coagulation conditions identical to those used for industrial rayon fibers. The spinnability of LSHEC was investigated by the variation of the storage modulus, loss modulus, and complex viscosity with the concentration of the LSHEC spinning solutions and temperature. It was found that the dissolution of LSHEC in sodium hydroxide aqueous solutions was an exothermic process, whereas the gelation of LSHEC was an endothermic process. Spinning conditions, comprising the concentration of the spinning solutions and corresponding spinning temperatures, were derived from the gelation onset curve theoretically. Moreover, combinations of the concentration of the spinning solution and the temperature of the coagulation bath could be predicted by the gelation onset curve. Finally, LSHEC fibers were prepared under the spinning conditions based on the gelation onset curve. The as‐spun LSHEC fibers had dry and wet tensile strengths of 1.59 and 0.47 cN/dtex, respectively, with a 0.30 ratio of the wet tensile strength to the dry tensile strength. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

用Weibull统计方法来评价上浆对炭纤维强度的影响

炭纤维属于脆性材料,其拉伸强度具有分散性,基本服从Weibull统计分布。本文采用这种方法对未上浆与上浆炭纤维的拉伸强度数据进行分析,说明上浆可使炭纤维的拉伸强度提高,分散性减小。     

碳纤维增强水泥/混凝土材料力学性能的若干研究

本文通过对水泥基体掺入碳纤维进行研究，得出了复合体抗压强度、劈拉强度与碳纤维掺量的关系。同时文中还利用聚丙烯腈纤维作对比研究，得出目前碳纤维作为增强体的优缺点，为碳纤维增强水泥基复合材料的推广应用提供更多的实验依据。     

Correlation between inhomogeneity in polyacrylonitrile spinning dopes and carbon fiber tensile strength

The nano‐scale and micro‐scale inhomogeneity of polyacrylonitrile (PAN) spinning dopes obtained from dynamic light scattering (DLS) experiment is correlated with the tensile strength of the resulting carbon fiber. The nanoscale inhomogeneity was estimated by calculating the diffusion coefficients from the slow relaxation mode of polymer solutions in DLS. The nanoscale inhomogeneity in the spinning dopes was found to be in the range of 1–45 nm. We also demonstrate mean of the count rate (MCR) obtained from DLS of PAN solution as a tool to detect the microscale inhomogeneity in the spinning dope for the first time. The MCR of spinning dopes varied from ~10.0 to 77.5 kcps (kilo‐counts per second). The tensile strength of carbon fibers from the precursor fiber spun from the spinning dopes in this study varied from 3 to 5.2 GPa. Correlation studies show that the microscale inhomogeneity in the spinning dope was a major contributor to the decrease in the tensile strength of carbon fibers in the range of 3–4.5 GPa. Contaminants causing microscale inhomogeneity in PAN powder were removed by using micelles, reverse micelles and frothing. The surfactant treated PAN polymer was characterized using a fourier transform infrared spectroscope, differential scanning calorimeter, and thermal gravimetic analyzer to demonstrate complete removal of surfactants. POLYM. ENG. SCI., 59:478–482, 2019. © 2018 Society of Plastics Engineers     

Producing high‐quality precursor polymer and fibers to achieve theoretical strength in carbon fibers: A review

The precursor fiber quality has a large impact on carbon fiber processing in terms of its performance, production yield, and cost. Polyacrylonitrile precursor fibers have been used commercially to produce strong carbon fibers with average tensile strength of 6.6 GPa. There is a scope to improve the average tensile strength of carbon fibers, since only 10% of their theoretical strength has been achieved thus far. Most attempts to increase the tensile strength of carbon fibers have been made during the conversion of precursor fiber to carbon fiber. This review highlights the potential opportunities to enhance the quality of the polyacrylonitrile‐based precursor fiber during polymer synthesis, spinning, and postspinning. These high‐quality precursor fibers can lead to new generation carbon fibers with improved tensile strength for high‐performance applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43963.     

Peracetic acid bleaching of banana fibre: Process optimisation

Banana is an important commercially available natural fibre, suitable for making coarse yarns. It has also potential for making fine home and apparel textiles after requisite chemical intervention or blending with other fine fibres. For making such products, chemical processing, namely bleaching, coloration and finishing, play an important role. Bleaching of fibre is generally carried out in highly alkaline condition and at high temperature of 85°C using hydrogen peroxide to achieve whiteness index of > 70 with about 25% loss in tensile strength. To achieve a similar whiteness index, while addressing strength loss, a fibre friendly low-temperature low-alkali based peracetic acid (PAA) bleaching of banana fibre has been proposed in the present article. Important bleaching process parameters, namely PAA concentration (10–30 g/L), time (60–180 min) and temperature (60–80°C), have been varied for optimisation of the bleaching process. Banana fibre bleaching using PAA concentration of 20 g/L at 70°C for 2 h can produce fibre with whiteness index of > 70, which is suitable for subsequent coloration. The PAA bleached banana fibre can retain 84% of its bundle strength and 95.6% of its weight. Physical (strength, fineness), chemical (attenuated total reflectance Fourier-transform infrared [ATR-FTIR], energy dispersive X-ray spectroscopy [EDX]), optical (colour) and morphological (scanning electron microscopy [SEM]) properties of banana fibres before and after bleaching were evaluated to study the efficacy of the process.