Production new chelating fibers of polyacrilonitrile for removing metal ions

In this work, raw acrylic fibers (RAF) have been modified with ethanolamine to provide new chelating fibers and prepared polyacrylonitrile‐monoethanolamine (PAN‐MEA). PAN‐MEA fiber was prepared by conversion nitrile groups into hydroxyle groups using ethanolamine solution with different concentration under refluxing at different temperatures and different times. The fiber structure has been investigated by different experimental techniques of characterization such as Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and the physical and mechanical properties has also been investigated in this study. The PAN‐MEA was examined as chelating material in a series of batch adsorption experiments for removal Cu (II), Pb (II) and Ni (II) ions. The ion adsorption of PAN‐MEA was determined with the atomic adsorption method. PAN‐MEA show adsorption metal ions more than usual fiber because of the modification.     

聚丙烯腈纤维改性条件优化及其对模拟电镀废水的净化作用

为了寻求低价、环保的电镀废水处理方案,将廉价的聚丙烯腈(PAN)纤维与羟胺试剂反应对PAN纤维进行改性,使其上氰基螯合获得偕胺肟基纤维。通过改变各种改性条件,探讨了改性条件对PAN改性纤维在重金属单离子溶液和多离子混合溶液中吸附性能的影响。结果表明:最佳改性条件为21.2 g/L PAN纤维,27.0 g/L盐酸羟胺,pH值为7.0,70℃下反应2 h;改性PAN纤维对模拟电镀废水中的Cu2+,Zn2+,Ni2+,Pb2+,Cd2+等重金属离子均有较好吸附性能,其中对Cd2+吸附效果最好,吸附量为55 mg/g;在多离子混合溶液中优先选择吸附Cd2+;改性PAN纤维再生效果优良,可重复利用。     

Preparation of aminated-polyacrylonitrile nanofiber membranes for the adsorption of metal ions: comparison with microfibers

Polyacrylonitrile nanofibers (PAN-nFs) were produced using the electrospinning method. Subsequently, the electrospun fibers were modified by diethylenetriamine to produce aminated polyacrylonitrile (APAN) nanofibers. Finally, the adsorbability of copper ions on the surface of the nanofibers was examined in an aqueous solution. Attenuated total internal reflection (ATIR) analysis confirmed the surface amination of the produced PAN-nFs. The grafting yield was calculated by the gravimetric method. The optimum condition was determined to yield the maximum grafting of amine groups to PAN with no losses in sample flexibility. Atomic absorption spectroscopy (AAS) was used to measure the copper ion concentration in the solution. Results indicate that the adsorption process in nanofibers is three times faster in comparison with microfibers. Moreover, the pH effect was studied based on the adsorption behavior of copper ions on the APAN nanofibers. In addition, thermodynamic parameters were calculated, revealing that the process was endothermic and demonstrating that randomness increased at the solid-solution interface during the process. The obtained enthalpy value indicates that the chelation of copper ions among the aminated polyacrylonitrile can be regarded as a chemical adsorption process. The adsorption data fit well with the Langmuir isotherm. The saturation adsorption capacity obtained from the Langmuir model for Cu(II) ions was 116.522 mg/g which is five times more than the reported value for APAN microfibers [S. Deng, R. Bai, J.P. Chen, Aminated polyacrylonitrile fibers for lead and copper removal, Langmuir,19 (2003)5058-5064]. Analysis using atomic force microscopy (AFM) showed that the surface roughness increased upon adsorption of the metal ion. Scanning electron microscopy (SEM) examination demonstrated that there were no cracks or sign of degradation on the surface after amination.     

Preparation of chelating fibrous polymer by different diamines and study on their physical and chemical properties

The present work describes a new modification process for producing a chelating ion‐exchanger fibers with a distinct selectivity for toxic heavy metal ions. Acrylic fibers were reacted with different diamine compounds in similar conditions. Modified acrylic fibers were prepared by partial conversion of the nitrile groups into amino groups under two‐step processes. In the first step, the pure liquid diamine was mixed with the fibers and in the second step, water was gradually added to the reaction flask to reach a predetermined 3M concentration at refluxing temperature of 91 ^°C. The aminated acrylic fibers (AAFs) were used as an ion adsorbent in a series of batch adsorption experiments for removal of chromium(III) and lead (II) ions. Experimental results showed that modified acrylic fiber with tetra methylene diamine (TMD) has the highest Pb(II) ion adsorption capacity. Results also showed aminated acrylic with ethylene diamine (EDA) has the most Cr(III) ion adsorption ability. Solubility tests showed, amination treatments give rise to the intermolecular crosslinkage in all samples. The Freundlich and Langmuir models simulated the adsorption equilibrium data of Cr(III) ions on modified fibers and their constants were determined.     

不同碳源多孔碳纤维制备及其吸附性能

先用静电纺丝法制备聚丙烯腈(PAN)、聚乙烯醇(PVA)和聚乙烯吡咯烷酮(PVP)基高分子纤维,然后将其碳化制备出不同碳源的多孔碳纤维材料。使用X-射线衍射仪、红外光谱仪、差示扫描量热仪和N₂吸脱附分析仪等手段表征了碳纤维材料的结构和性能。结果表明,PAN基碳纤维的比表面积最大(113.5 m²/g)、微孔较多,对刚果红的吸附量最大(560.2 g/kg)。根据吸附动力学模型和吸附等温线的分析结果,碳纤维对刚果红的吸附属单层吸附。结果还表明,温度越高材料的吸附速率越高但是吸附量没有明显的变化;在酸性条件下PVA基碳纤维保持较高的吸附活性,而PAN基碳纤维则与之相反;刚果红水溶液的pH值对PVP基碳纤维吸附活性的影响很小。     

Comparative study on the mechanical and thermal properties of two different modified PAN fibers and their Fe complexes

The polyacrylonitrile (PAN) fibers were modified with hydroxylamine and its mixture with hydrazine to prepared the amidoximated PAN fibers (denoted as AO-PAN) and mixing modified PAN fibers (denoted as M-PAN) respectively, and then both of which were reacted with Fe³⁺ ions to form two modified PAN fiber–Fe complexes (denoted as Fe–AO-PAN for AO-PAN and Fe–M-PAN for M-PAN). Their mechanical properties were evaluated and compared with respect to the breaking strength and elongation at break in both dry and wet conditions, and two important effecting factors including weight gain rate of the PAN fiber after modification and Fe content remained in the PAN fiber were investigated. Besides, thermal behavior of the modified PAN fibers and their Fe complexes was also examined by DSC and DMA methods. The results indicated that higher weight gain rate imparts the reduced breaking strength to two modified PAN fibers, and which is found to be further lower in wet state. The mechanical properties of the modified PAN fibers-Fe complexes, especially Fe–AO-PAN varied with Fe content (C_Fe–PAN). Moreover, two critical C_Fe–PAN values are observed to be 79.75 mg/g for Fe–AO-PAN and 28.35 mg/g for Fe–M-PAN, respectively, at which they show a minimum values of breaking strength and elongation at break. Also, Fe–AO-PAN is much higher than Fe–M-PAN in terms of the critical C_Fe–PAN value, which is mainly attributed to the difference in molecular structure between them. Thermal behavior of the modified PAN fibers and their Fe complexes is also greatly affected by their modification methods.     

水相悬浮聚合制备MWCNTs/PAN复合微球及其电纺纤维

先用Fenton试剂（过氧化氢/硫酸亚铁）对多壁碳纳米管进行改性处理（-fMWCNTs）,再通过水相悬浮聚合法制备了多壁碳纳米管/聚丙烯腈（-fMWCNTs/PAN）复合微球,用静电纺丝技术制备了-fMWCNTs/PAN复合纤维膜。通过扫描电镜（SEM）、热重分析仪（TGA）和万能试验机研究了-fMWCNTs对电纺纤维...     

含铁碳纳米纤维的制备与表征

在聚丙烯腈的N,N-二甲基甲酰胺和四氢呋喃的混合溶剂中添加聚二茂铁硅烷,通过溶液的静电纺丝,制备了含聚二茂铁硅烷微相分离的微纳前驱体纤维,经预氧化和炭化,得到负载Fe的碳纳米纤维膜;利用SEM、SEM-EDS和XPS分别对纳米纤维的形貌、尺寸、结构和组成进行了表征。     

湿法纺丝Amid-CNT/PAN复合纤维的结构与性能

通过溶液聚合得到胺化碳纳米管（Ami-CNT）/聚丙烯腈（PAN）复合溶液, 采用湿法纺丝技术制备了Amid-CNT/PAN复合纤维。利用红外光谱、 拉曼光谱、 差示扫描量热仪、 热失重仪和扫描电镜等方法分析Amid-CNT对PAN纤维结构的影响。结果表明: Amid-CNT与PAN大分子之间有很强的化学作用力; Amid-CNT在复合纤维中具有很高程度的取向, 使PAN纤维中氰基的取向从1.61提高到了2.30; 复合纤维在空气中的起始放热温度相对PAN纤维从212.30℃提前到206.01℃, 反应放热量从3054J/g降低到2346J/g; 复合纤维比PAN纤维的起始失重温度提前了3.7℃, 在700℃时的剩余质量提高了13.5%; 复合纤维的断面比PAN纤维具有更多的絮状结构。      

PAN基碳纤维原丝的高锰酸钾改性(英文)

本文使用质量浓度为5%的高锰酸钾溶液对PAN基碳纤维原丝进行不同时间的改性,并利用不同的测试手段对经过改性的原丝进行了表征。相比未经改性的原丝,改性原丝具有较低的拉伸强度,在相当于预氧化(稳定化)温度范围的条件下释放的热量较少。这些实验结果表明,高锰酸钾溶液可以将高锰酸根离子引入PAN原丝内部,使其与丙烯腈单元发生反应,从而有利于纤维的氧化的环化反应。此外,本文还讨论了改性时间对原丝性能的影响。     

DSC Study on the Polyacrylonitrile Precursors for Carbon Fibers

Different polyacrylonitrile (PAN) precursor fibers that displayed various thermal properties were studied by using differential scanning calorimetry (DSC). Results showed that some commercial PAN precursor fibers displayed double separated peaks and these fibers were of high quality because of their process stability during their conversion to carbon fibers of high performance. Some fabrication processes, such as spinning, drawing, could not apparently change the DSC features of a PAN precursor fiber. It was concluded that the thermal properties of a PAN precursor fiber was mainly determined from its comonomer content type and compositions.     

腈纶废丝/硬脂酸相变纤维的制备及性能研究

以硬脂酸(SA)为相变储能物质,腈纶废丝(PAN)为聚合物基体,采用湿法纺丝法制备了PAN/SA相变纤维。研究表明,相变纤维中PAN与SA大分子依靠分子间作用力结合在一起;SA在纤维基体中分布均匀,无相分离现象;PAN/SA相变纤维的相变焓达到48.84J/g,且DSC热循环显示纤维具有较好的热稳定性;PAN/SA相变纤维相对于PAN纤维具有良好的保温性;PAN/SA相变纤维在110℃热空气中迅速干燥的力学性能优于常温处理的力学性能。     

Preparation and electrochemical properties of carbon nanofiber composite dispersed with silver nanoparticles using polyacrylonitrile and beta-cyclodextrin

A simple one-step method was used for preparing the beta-cyclodextrin/polyacrylonitrile (PAN) nanofibers deposited with silver nanoparticles by electrospinning and followed by the reduction of the Ag+ ions. The nano-composite fibers were stabilized at 280 degrees C in air and activated at 800 degrees C for 1 h in steam/N2. The structures of nano-composite fibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier-transform infrared (FTIR) spectroscopy, and X-ray diffraction analysis (XRD). The electrochemical behaviors of the composite of carbon nano-fibers were investigated by cyclic voltammetry and charge/discharge tests.     

Carbon fibers modified with carbon nanotubes

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.     

热氧稳定化过程温度效应对PAN纤维径向氧元素扩散速率的作用

在梯度升温和恒温两种模式下,对聚丙烯腈（PAN）纤维进行了热氧稳定化处理,借助FTIR、核磁共振碳谱（13 C-NMR）、元素分析（EA）、DSC、X-射线能谱（EDS）、密度等多种表征手段系统研究了不同温度下热氧稳定化纤维皮-芯结构的形成机制和氧元素的扩散速率。研究结果表明：氧化反应速率小于氧的扩散速率时,PAN纤维...     

提高聚丙烯腈基炭纤维质量的方法

聚丙烯腈是炭纤维的重要原材料。高质量的聚丙烯腈才有可能生产出高质量的原丝,而高质量的原丝是保证高质量炭纤维的必在条件。聚丙烯腈的分子量及其分布、等规度、共聚结构单元的比例及分布上的缺陷直接影响着聚丙烯腈的质量,进而影响原丝及其炭纤维的性能。从调整聚丙烯腈分子量及分布、等规度、共聚结构单元的比例及分布入手,论述了提高聚丙...     

Surface State of Carbon Fibers Modified by Electrochemical Oxidation

Surface of polyacrylonitrile (PAN)-based carbon fibers was modified by electrochemical oxidation. The modification effect on carbon fibers surface was explored using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Results showed that on the modified surface of carbon fibers, the carbon contents decreased by 9.7% and the oxygen and nitrogen contents increased by 53.8% and 7.5 times, respectively. The surface roughness and the hydroxyl and carbonyl contents also increased. The surface orientation index was reduced by 1.5% which decreased tensile strength of carbon fibers by 8.1%, and the microcrystalline dimension also decreased which increased the active sites of carbon fiber surface by 78%. The physical and chemical properties of carbon fibers surface were modified through the electrochemical oxidative method, which improved the cohesiveness between the fibers and resin matrix and increased the interlaminar shear strength (ILSS) of carbon fibers reinforc     

Fabrication of carbon papers using polyacrylonitrile fibers as a binder

Carbon papers (CPs) have been fabricated using wet-laying carbon fibers (CFs) and polyacrylonitrile (PAN) fibers. Scanning electron microscopy revealed that the PAN fibers tightly interconnected the CF junctions with the pores between the fibers. The tensile strength of the carbon webs (CWs) increased as the fraction of PAN fibers used as the binder increased. The CW fabricated with 0.15 wt% PAN fibers had a tensile strength six times greater than that of the CW without PAN fibers. Moreover, by mixing the CFs with PAN fibers in water, the CFs separated from each other in the webs due to the interruption of hydrophobicity between the CFs. After mixing with PAN fibers, the CWs were carbonized at 1200 °C in the presence of a phenolic resin. The PAN fibers maintained their morphology due to their high carbon content after carbonization. The electrical resistivity of the CPs with high PAN fiber content was significantly lower than that of a CP without PAN fibers due to the interconnection of the CFs by the carbonized PAN fibers.     

酰氯化工艺对腈纶表面接枝蛋白质效果的影响

对酰氯化工艺条件对腈纶表面接枝蛋白质改性效果的影响进行了研究,结果表明:酰氯化工艺条件对蛋白质接枝改性腈纶的制备具有重要作用,无论是酰氯化反应温度、反应时间,还是氯化亚砜加入量都会对纤维的蛋白质接枝率产生重要影响。研究表明,氯化亚砜加入量约占接枝纤维量的10%,反应温度105℃~110℃,反应时间在10 min~30 min之间时,可以制得接枝率较高的蛋白质接枝改性腈纶。进一步的SEM观察和红外分析同时证明在腈纶表面接枝蛋白质效果明显。     

上浆剂对炭纤维表面和环氧树脂复合材料的影响

采用两种上浆剂对聚丙烯腈(PAN)基炭纤维进行表面上浆,利用扫描电子显微镜(SEM)、原子力显微镜(AFM)、X射线元素分析(XPS)和反向气相色谱(IGC)研究了未上浆、上浆炭纤维的表面形貌、化学组成及纤维表面能,测试了未上浆和上浆炭纤维所制备复合材料的层间剪切强度(ILSS)并用SEM观察其断面形貌。结果表明,上浆后炭纤维表面变平滑,纤维表面n(O)/n(C)明显提高,含氧官能团(羟基、羧基)增加,炭纤维表面能降低。上浆后,复合材料的ILLS有所提高。