电纺CoFe2O4纳米纤维及其磁性研究

采用溶胶-凝胶过程和静电纺丝技术,以三氯化铁(FeCl3·6H2O)、醋酸钴(Co(CH3COO)2·4H2O)和聚乙烯醇(PVA)为前驱物,制得PVA/FeCl3/Co(CH3COO)2复合纳米纤维.经高温煅烧,制备了CoFe2O4纳米纤维.利用扫描电镜(SEM)、红外光谱(FT-IR)、差热-热重(TG-DTA)和X射线衍射(XRD)等分析测试手段对样品进行了表征,并研究了其磁性质.结果表明:静电纺丝技术制备的CoFe2O4纳米纤维为规则的一维结构,直径分布均匀,具有良好的铁磁性.     

A Composite of Electrospun Nylon-6 Nanofibers and in-situ Polymerized Polypyrrole as an NH3 Gas Sensor

1 Results Electrospinning provides a simple and versatile method for preparing nanofibers with different morphology, such as porous fibers and nanotubes. It has been widely used for preparing nanomaterials with unique properties and potential applications in medicine, catalyst, photonics and sensors[1, 2]. In this study, uniform Nylon-6 nanofibers with diameter of ≈300 nm by electrospun from formic acid solution containing 15%wt Nylon-6. Polypyrrole (PPy) was then deposited on the nanofibers by in-situ ...     

静电纺丝方法制备CexZr1-xO2（x=0．5）纳米纤维

通过溶胶-凝胶过程,以聚乙烯醇和Zr（NO3）4和Ce（NO3）3形成的溶胶为前驱物,采用静电纺丝技术,并经焙烧等后处理过程,制备了CexZr1-xO2（x=0．5）复合氧化物纳米纤维,利用扫描电镜、X射线衍射仪、红外光谱仪、拉曼光谱仪,对产物进行表征。结果表明,500℃焙烧后产物外形均一,直径在100nm以下,具有大的长径比,且颗粒分布均匀。     

纳米碳纤维复合材料的阻温特性研究

采用超声波分散的方法制备了纳米碳纤维/环氧树脂复合材料,研究了纳米碳纤维含量对复合材料导电性能的影响,并对其伏安特性及阻温特性进行了探讨.研究结果表明:复合材料的电阻率随纳米碳纤维质量分数的增加呈几何级数递减,其渗滤区域在0.1%~0.2%之间;其电流-电压关系基本符合欧姆定律;复合材料在升温和降温过程中均呈现出正温度效应和负温度效应,并具有较好的回复稳定性.     

Preparation of Si-doped and cross linked carbon nanofibers via electrospinning and their supercapacitive properties

In this work, Si-doped cross linked carbon nanofibers(Si/CNF) were prepared by electrospinning polyacrylonitrile(PAN) solutions containing polyhedral oligomeric silsesquioxane(POSS) as Si source, followed by thermal treatments. Scanning electron microscope(SEM) observations showed the smooth surfaces of pure PAN nanofibers, while PAN/POSS nanofibers with obviously rough or porous surfaces were obtained with relatively high POSS content. X-ray diffraction(XRD) identified the presence of POSS in the composite nanofibers. After thermal treatments, cross linked Si/CNFs with various morphologies were obtained. Energy-dispersive X-ray(EDX) and X-ray photoelectron spectroscopy(XPS) analyses confirmed the successful incorporation of Si into CNFs. Raman spectra suggested the degree of carbon ordering of Si/CNFs reduced slightly when compared with pure CNF. The obtained nanofibers exhibited typical performances of electric double-layer capacitors(EDLC).The specific capacitance of Si/CNF showed a moderate increase with POSS content and reached a maximum of175 F/g at 1 A/g with PAN:POSS equal to 100:5. Meanwhile Si/CNFs exhibited excellent cycling stability after1000 cycles. The influence of POSS on the capacitive performance might be attributed to the combined effects of evolution of morphology, conductivity and surface properties of Si/CNFs.     

纺丝液的导电性对静电纺丝单根纤维的直径及稳定长度的影响

选取PAN/DMAC溶液进行静电纺丝,用添加不同质量分数的氯化锂（LiCl）来控制纺丝液的导电性.研究纺丝液的导电性对静电纺丝单根纤维的直径及稳定长度的影响.实验表明射流沿轴向半径的变化依赖于盐的含量,随着LiCl含量的增加,r～2α关系式中的指数α增大.实验同时表明射流稳定长度随射流表面电荷的增加而减小,随着溶液导电率的增加,射流的稳定长度变短,静电纺丝射流的不稳定现象提早发生.     

CNFs掺杂浓度对CNFs／LDPE复合材料空间电荷的影响

为改善低密度聚乙烯的电学性能,文中将镀镍后的碳纤维添加混入低密度聚乙烯中,通过熔融共混技术,制成CNFs／LDPE半导电层＋绝缘层双层样片．采用电声脉冲法（PEA）测量其空间电荷分布．实验结果表明：随着直流电场的增加,在CNFs／LDPE半导电层＋纯绝缘层双层样片中,当CNFs质量分数低于1％时,CNFs／LDPE半导电层对电场的削弱作用相对较小,样品中残余了相对较多的空间电荷．当CNFs质量分数超过1％时,CNFs／LDPE半导电层的导电机制发生了改变,注入的空间电荷量很少且短路后几乎无残余．尤其是CNFs质量分数为5％时,样品内除阴极附近有微量电荷外,样品内部几乎无空间电荷分布．     

钨酸铋／预氧化腈纶复合纳米纤维制备的研究

以五水硝酸铋、二水钨酸钠和腈纶为原料,通过静电纺丝的方法制备钨酸铋／预氧化腈纶复合纳米纤维前体,并将制备的复合纳米纤维前体在200℃下反应,制得钨酸铋／预氧化腈纶复合纳米纤维．利用FE-SEM、XRD对制得的复合纳米纤维进行了表征．探讨了纺丝电压、接收距离和纺丝流速对纤维直径和形态的影响．结果表明,纺丝电压为22kV、接收距离为15cm、纺丝流速为0．2mL／h时,所制备的复合纳米纤维前体形态较好,纤维平均直径为93nm．经过200℃处理后,钨酸铋在复合纳米纤维上形成,得到的钨酸铋／预氧化腈纶复合纳米纤维的平均直径为113nm．     

静电纺丝法制备高分子纳米纤维的成因研究

对静电纺丝法制备高分子纳米纤维的成因进行了探究,主要通过分析高分子的结构与纺丝条件,寻找到静电纺丝法制备纳米纤维材料的一般规律。通过扫描电子显微镜(SEM)观察了高分子结构、分子量、溶液浓度和溶剂对高分子纳米纤维形貌的影响。实验结果表明:决定能否形成纤维的主要因素是高分子的结构和分子量,纤维的直径随着高分子溶液浓度的增加而增加,溶剂的挥发速率对纤维的形貌有决定性的影响。因此,利用静电纺丝法制备纳米纤维时应着重考虑以上四个因素的影响。