共查询到19条相似文献,搜索用时 140 毫秒
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《化工新型材料》2016,(7)
利用碘吸附法、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和小角x射线(SAXS)等测试方法对国内外企业生产的几种聚丙烯腈(PAN)基碳纤维原丝的形貌结构、组织结构和孔分布等微观结构进行了系统的测试与研究。结果表明,各种PAN纤维的表面均有沟槽、裂纹等缺陷;内部都存在着尺寸分布不均的孔结构,包括大孔和微孔。对各种纤维原丝碘吸附的数值进行对比分析发现,日本三菱和东丽公司生产的PAN纤维碘吸附数值小,纤维的致密性较高。对各种PAN纤维的SAXS测试结果分析发现,PAN纤维内都存在尺寸分布一定且具有一定取向性的微孔结构。这些微观结构对PAN纤维的性能有着不同的影响作用,并决定着由其生产的PAN基碳纤维的结构与性能。 相似文献
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聚丙烯腈(PAN)基碳纤维由于性能优异、制备工艺简单,被广泛应用于各产业,但其存在表面化学惰性强、力学性能仍有很大提升空间等问题,为此研究人员提出了多种改性方法。其中,γ射线辐照是一种能够实现碳纤维表面活性和力学性能协同提高的改性方法,并且能够应用于PAN基碳纤维制备(PAN原丝)及其后处理全过程。本文概述了γ辐照对PAN原丝和PAN基碳纤维的微观结构、表界面性能和力学性能等方面的影响,重点总结了γ辐照下PAN原丝分子结构的演化机制,原丝辐照对成品碳纤维力学性能的影响,γ辐照下碳纤维不同微区结构演化和力学性能的关系,展望了未来γ射线辐照改性PAN基碳纤维的发展方向与前景。 相似文献
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选取碳纤维拉伸强度不同的PAN原丝,通过X射线衍射(XRD)、差示扫描量热仪(DSC)、扫描电镜(SEM)等,对其聚集态结构和形态结构进行了表征。通过分析原丝不同层次结构,建立不同结构与性能之间的关系,并对原丝不同结构对碳纤维强度的影响大小进行了对比。结果表明,结晶度、取向度和致密性是影响碳纤维强度的主要因素,随着晶态结构和取向结构的完善、致密性的提高,碳纤维强度随之增加。但原丝不同结构对碳纤维强度的影响大小是有区别的,从大到小依次为:致密性、取向度、结晶度与微晶尺寸。 相似文献
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在使用PAN.F(聚丙烯腈原丝)为前躯体制备PAN.CF(聚丙烯腈基碳纤维)的过程中,经过预氧化反应生成的PAN.OF(聚丙烯腈基氧化纤维,俗称预氧丝)是其非常重要的中间过程,PAN.OF的皮芯结构直接影响着PAN.CF的力学性能。借助超薄切片机、电子显微镜、扫描电镜和材料试验机等表征测试手段,系统研究了PAN.OF的皮芯结构对PAN.CF力学性能的影响。研究认为:通过原丝的细旦化和预氧化过程条件的优化可以有效控制或消除PAN.OF的皮芯结构,得到抗拉强度5600MPa以上,弹性模量290GPa以上的碳纤维。 相似文献
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以偶氮二异丁脒盐酸盐(AIBA)、偶氮二异丁腈(AIBN)为引发剂,分别制备了具有不同端基结构的丙烯腈与衣康酸共聚物PAN-AIBA和PAN-AIBN,采用湿法纺丝技术制备PAN原丝。采用两种梯度升温方式对PAN原丝进行热稳定化处理,对优选的预氧化纤维进行高温碳化制得碳纤维。采用多种手段表征纤维结构与组成的变化规律。结果表明,脒端基可提高PAN预氧纤维的相对环化率,使其氧含量和体密度平稳增长,因此有利于预氧化纤维的结构调控。PAN-AIBA基碳纤维的皮芯结构差异小于PAN-AIBN基碳纤维,与其相对温和的热稳定化行为相符。 相似文献
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预氧化是制备碳纤维非常重要的一个环节,制得预氧化丝的性能直接决定最终碳纤维的性能,因此研究预氧化过程对预氧化丝结构性能的影响规律具有重要意义。通过广角X射线衍射点光源取向测试和小角X射线散射实验,计算得到了聚丙烯腈(PAN)基碳纤维原丝与不同处理时间下预氧丝取向度、线结晶度、长周期L、晶区厚度Lc、无定形区厚度La等微观结构参数。采用元素分析仪和单纤维强力仪研究了该系列PAN基碳纤维原丝、预氧丝的元素组成和力学性能随预氧化时间的变化,明确了PAN基碳纤维预氧丝内部微观结构参数、元素含量与其力学性能的关系。 相似文献
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A new spinning method - pregelled gel spinning method for polyacrylonitrile (PAN) precursor fiber was reported. The physical and structural properties of the pregelled gel spun PAN precursor fibers as well as dry-jet wet spun PAN precursor fibers were studied. Compared with the dry-jet wet spun fibers, the pregelled gel spun fibers had reduced core-shell difference, circular cross sections and fewer internal pores. The pregelled gel spun fibers were found to have higher crystallinity and larger crystallite size than the dry-jet wet spun fibers. The tensile stress relaxation tests suggested that the pregelled gel spun fibers had higher elasticity and better developed supermolecular structure. 相似文献
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聚丙烯腈(PAN)和聚甲基丙烯酸甲酯(PMMA)共混膜的结构和尺寸可由两组分比例和分子量调整。以PAN为碳前驱体,PMMA为热分解聚合物,并控制m(PAN)/m(PMMA)为30/70和70/30,通过湿法纺丝制备了PAN/PMMA共混纤维。以m(PAN)/m(PMMA)为30/70和70/30的共混纤维为原丝经碳化后获得了纳米碳纤维(CNFs)和多孔碳纤维(PCFs)。利用扫描电镜观察了所得CNFs和PCFs的形貌,发现单根CNFs的直径为50~150nm,PCFs中孔的直径为0.1~1μm。由CNFs和PCFs的拉曼光谱分析了不同碳化温度对CNFs和PCFs石墨化程度的影响,结果表明随碳化温度升高,石墨化程度也增加,同时电导率也随之提高。 相似文献
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径向结构是实现PAN基石墨纤维高模高强化的重要影响因素之一,有效调控、优化石墨纤维径向结构分布特征对制备高性能石墨纤维具有重要的指导意义。通过对径向分布特征不同的预氧纤维进行炭化、石墨化处理,研究PAN预氧纤维径向结构分布特征对石墨纤维径向结构分布特征和力学性能的影响。结果表明,石墨纤维径向结构是在预氧纤维径向结构上继承发展而来,含有较多共轭结构的预氧纤维皮部区域在炭化、石墨化处理后石墨化程度较高,有利于纤维力学性能提高,但过高的预氧化温度不仅使纤维中含氧结构增多,还使石墨纤维径向结构差异过大,导致石墨纤维的结构致密性下降,皮芯间产生剪切应力,纤维承载能力下降,力学性能受损。 相似文献
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Aneta Fraczek-Szczypta Maciej Bogun Stanislaw Blazewicz 《Journal of Materials Science》2009,44(17):4721-4727
Carbon nanotubes were used to modify a polyacrylonitrile (PAN) polymer solution before the manufacture of the carbon fiber
precursor. The modified PAN fibers were spun from a dimethylformamide solution containing a small amount of single-walled
carbon nanotubes. The fibers were characterized by thermogravimetry and optical and scanning electron microscopy. Structure,
morphology, and selected properties of the composite polymeric fibers and the fibers after carbonization are characterized.
The mechanical properties of the fibers are examined. It is found that nanotubes in the PAN solution have a strong tendency
to form agglomerates that inhibit suitable macromolecular chain orientation of the carbon fiber precursor. Fibers manufactured
from such a solution have similar mechanical properties to those from a pure PAN precursor, and after carbonization the resultant
carbon fibers are very weak. A comparison of pure carbon fibers and those containing nanotubes reveals slight differences
in their structural ordering. 相似文献
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高性能碳纤维的研制—连续预氧化过程中纤维序态结构的变化EI 总被引:3,自引:0,他引:3
报道了制备高性能碳纤维的连续预氧化过程中,一定张力下聚丙烯腈(PAN)原丝纤维序态结构的变化历程。结果表明,PAN纤维序态结构的演变经历三个阶段,即序态结构趋于完善,序态结构快速变化和慢速变化。 相似文献
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In this study, polyacrylonitrile (PAN) composite nanofibers containing different amounts of silica nanoparticulates have been obtained via electrospinning. The surface morphology, thermal properties and crystal structure of PAN/silica nanofibers are characterized using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, wide-angle x-ray diffraction (WAXD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). The results indicate that the addition of silica nanoparticulates affects the structure and properties of the nanofibers. In addition to PAN/silica composite nanofibers, porous PAN nanofibers have been prepared by selective removal of the silica component from PAN/silica composite nanofibers using hydrofluoric (HF) acid. ATR-FTIR and thermal gravimetric analysis (TGA) experiments validate the removal of silica nanoparticulates by HF acid, whereas SEM and TEM results reveal that the porous nanofibers obtained from composite fibers with higher silica contents exhibited more nonuniform surface morphology. The Brunauer-Emmett-Teller (BET) surface area of porous PAN nanofibers made from PAN/silica (5?wt%) composite precursors is higher than that of pure nonporous PAN nanofibers. 相似文献
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Dongbing Jin Ying Huang Xiangluan Liu Yunzhao Yu 《Journal of Materials Science》2004,39(10):3365-3368
The influences of functional polysiloxanes bearing epoxy or amino groups on the thermooxidative stabilization process of the PAN precursor fibers were studied. Structural changes were investigated by FT-IR spectroscopy. It was found that formation of the conjugated ladder structure in the precursor fiber was promoted by the functional polysiloxanes. Meanwhile heat releasing in the thermooxidative stabilization process was depressed. It seems that the coatings of the functional polysiloxanes on the fibers retarded oxygen diffusion into the PAN precursor fibers. The functional polysiloxanes did not affect carbonization in an inert atmosphere following the thermooxidative stabilization process. 相似文献
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聚丙烯腈(PAN)纤维在纺丝过程中会形成受迫高弹形变,在受热条件下会出现物理收缩为代表的热松弛行为,发生解取向。通过热力学分析仪(TMA),动态力学分析仪(DMA),广角X射线衍射法(WAXD)等手段研究PAN纤维的热松弛行为,并且通过张力和温度对其进行控制。结果表明:PAN纤维纺丝过程形成的高弹形变约占10%以上,在高温下会迅速回复发生解取向。通过施加适当的张力和提高温度可以在不损失取向结构的同时将高弹形变转化为塑性形变。在张力和温度的作用下,纤维内部聚集态结构重排,分子链取向进一步提高,晶态结构进一步完善,纤维尺寸稳定性提高50%以上。研究表明经此方法处理的碳纤维微晶沿分子链排列更加规整,性能得到了有效提升。 相似文献