两种有机黏土与PA6复合纳米纤维的结构与热稳定性的比较

通过简单的溶液混合及静电纺丝的方法制备了含有两种不同有机黏土的聚酰胺6(PA6)复合纳米纤维.首先将有机黏土分散在N,N-二甲基甲酰胺(DMF)中,PA6溶解于甲酸中,然后将两种溶液进行充分混合后制得静电纺丝液,最后通过静电纺丝来制备PA6复合纳米纤维.通过XRD、XPS、SEM和TGA分别对纯PA6纳米纤维和两种复合纳米纤维的结构、形貌和热稳定性进行表征与比较.XRD和XPS的研究结果表明,黏土层在复合纳米纤维中分散均匀.TGA的分析表明,由于有机黏土的隔热作用,PA6复合纳米纤维在700℃时的热稳定性和残余量都比PA6纳米纤维的高.并且,硅酸盐晶格上铁离子的作用使得PA/Fe-OMT复合纳米纤维的残余量也明显高于PA/Na-OMT复合纳米纤维.     

CS/PA66复合纳米纤维的静电纺丝制备与药物缓释性研究

采用单一溶剂甲酸溶解壳聚糖(CS)和聚酰胺66(PA66),以静电纺丝的方式成功制得不同质量比的CS/PA66复合纳米纤维,通过红外光谱、扫描电镜等对复合纳米纤维的形貌、结构进行表征。结果证明:采用静电纺丝制得不同CS∶PA66质量配合比CS/PA66复合纳米纤维,纤维直径为40~100nm,纤维分布均匀,具有很好的连续性,增加黏度和电导率能够减小CS/PA66复合纳米纤维直径,提高复合纳米纤维堆叠密集度。CS∶PA66质量配合比为2∶8,CS/PA66复合纤维载药量为20%,释放50h,药物累计释放率最高达到88%,CS/PA66作为载药体系具有较好的药物缓释效果。     

静电纺工艺参数对含银PA6纳米纤维直径的影响

为了研究静电纺工艺参数对含银PA6纳米纤维直径分布的影响,采用静电纺丝技术,在不同含银量、纺丝液质量分数、纺丝电压、接收距离(C-SD)、喷嘴直径条件下制备出含银PA6纳米纤维膜.利用扫描电镜(SEM)及相关软件分析纳米纤维直径分布及形态,在银溶胶质量分数0.2%～0.4%、纺丝液质量分数10%～16%、纺丝电压12～21kV、接收距离9～18cm、喷嘴直径0.5～1.2mm的实验范围内,纳米纤维的平均直径为70～90nm;纳米纤维直径随银溶胶质量分数的增加而减小,随纺丝液质量分数的增加而增大,随喷嘴直径的增大而增大;电压和接收距离对纳米纤维直径的影响较小.     

静电纺PA56纳米纤维膜的制备及力学性能研究

配制不同浓度的PA56(锦纶56)纺丝液,采用静电纺丝技术制备PA56纳米纤维膜。通过扫描电子显微镜观察膜表面的微观形貌,探究纺丝液浓度对纤维形貌和直径的影响。结果表明:当纺丝液浓度为2.0g PA56/10mL HCOOH,推进速度为0.5mL/h,纺丝温度为45℃时,纺丝效果最佳,此时纤维直径为0.155μm。采用电子万能试验机对制得的PA56纳米纤维膜的力学性能进行测试,在最佳条件下所制膜的弹性模量为142.43MPa,断裂伸长率为19.9%,拉伸断列应力为15.02MPa,拉伸强度为15.02MPa,具有较好的力学强度。     

仿树枝状PA6纳米纤维膜电纺工艺研究

在PA6纺丝液中添加有机盐四丁基氯化铵(TBAC),通过静电纺丝成功制得仿树枝状PA6纳米纤维膜,通过扫描电镜探讨聚合物用量,添加物用量以及纺丝工艺参数对纤维形貌的影响,分析表明当PA6用量为14%,TBAC用量为4%,电压为45kV,接收距离为15cm,注射速率为0.1mL/h时,纤维平均直径为116nm,制得的纳米纤维膜分支纤维较多,呈现形貌良好的树枝状结构。     

二醋纤纺丝液性能对静电纺纤维的影响

为优化二醋酸纤维素的纺丝加工成型工艺,研究了二醋片特性黏度、浓度和溶剂配比对纺丝液性能的影响,并探索了纺丝液性能与所纺纤维形貌和直径之间的关系。结果表明:随着特性黏度和浓度的增大,纺丝液黏度增大,流动性能变差,所纺纤维直径增大;当混合溶剂中丙酮含量低时,纺丝液因黏度和表面张力大,电导率小而无法纺丝只能收集到珠状液滴;逐渐增加丙酮含量,黏度和表面张力减小,电导率增大,所纺纤维直径增大;当使用丙酮/N,N-二甲基乙酰胺的体积比为3∶2时,可以收集到光滑无缺陷的纳米纤维;当丙酮含量较高时,纺丝液因溶剂挥发速率快而凝固从而无法纺丝。     

静电纺丝制备多孔纳米纤维的研究进展

静电纺丝是一种能够制备连续纳米纤维的简单、方便、高效的方法,在组织工程、药物缓释和催化剂负载等领域应用广泛,近年来该方法制备的表面或内部具有多孔结构的纳米纤维因具有超高的比表面积而备受关注。综述了电纺多孔纳米纤维的制备方法和成孔机理,详细讨论了液相分离致孔和固相分离致孔的研究现状和未来发展方向。从纺丝液溶剂性质展开,结合混溶、控温、控湿等实验条件,分析了射流固化速率和溶剂挥发速率的相互作用关系,并提出多手段共用制备孔结构可控的多孔纳米纤维的方法。     

静电纺PA6/CTS/LiCl纳米纤维膜的制备研究

采用静电纺丝技术制备聚酰胺6(PA6)/壳聚糖(CTS)/氯化锂(LiCl)纳米纤维膜,考察了CTS、PA6及LiCl添加量对纳米纤维膜形貌、直径分布的影响。通过场发射扫描电子显微镜、傅里叶变换红外光谱仪对纳米纤维膜的微观形貌及表面官能团进行分析。结果表明:在PA6添加量为1.8g、CTS添加量为0.3g、LiCl添加量为0.12g的条件下,纺丝效果最佳,纤维平均直径为103nm。傅里叶变换红外光谱分析表明PA6/CTS/LiCl纳米纤维膜具有PA6和CTS的特征吸收峰,PA6/CTS/LiCl纳米纤维膜有望作为滤膜材料使用。     

聚酰亚胺纳米纤维的制备及性能表征

为了研究一步法所纺聚酰亚胺(PI)纳米纤维的结构与性能,采用静电纺丝技术,以热塑性聚酰亚胺粉末为原料,N,N-二甲基甲酰胺(DMF)、N,N-二甲基乙酰胺(DMAc)、吐温80等按一定比例混合的溶液为溶剂,制备了平均直径在0.313~0.785μm的2种PI纳米纤维,并对其结构和性能进行表征。结果表明,所纺纳米纤维表面无微孔,纤维直径随纺丝液浓度的增加而增加;随纺丝电压和纺丝距离的增加而先减小后增加。此外,不同溶剂体系所纺PI纳米纤维的结构和性能存在很大差异,PI DMF-DMAc纳米纤维的结构规整性、力学性能(断裂强度24.8 MPa)和热稳定性(热分解温度535℃)均高于PI Tween80-DMF-DMAc纳米纤维(其断裂强度为16.5 MPa,热分解温度为421℃)。     

微米级PVP纤维的制备和表征

通过静电纺丝技术将聚乙烯吡咯烷酮(PVP)制成微米级纤维,并通过场发射扫描电镜对其微观形貌进行了表征,考察了纺丝液浓度、工作电压和溶剂种类等工艺参数对PVP纤维形貌的影响。结果表明,随着PVP纺丝液浓度以及电压的逐渐增大,纤维直径也随之增大,且直径分布更加均一。当以乙醇为溶剂,PVP质量浓度为45%,电压为23kV时,所得PVP纳米纤维的平均直径为1.65μm,直径分布较均一。     

PASS溶液性质对静电纺丝可纺性及纤维形貌的影响

选取苯酚和四氯乙烷的混合物作溶剂,采用不同分子量的聚芳硫醚砜(PASS)树脂配制不同浓度的溶液,考察了溶液动态流变性能、表面张力、导电率对静电纺丝可纺性以及纤维形貌的影响。结果发现溶液的可纺性有实数黏度依赖性,纤维直径受溶液黏度的影响最大。     

Price Adjusted Single Sampling with Quadratic Indifference

The purpose of this paper is to expand the application of Price Adjusted Single Sampling, PASS, to include quadratic indifference. The concept of PASS is first reviewed. Secondly, the statistical background of PASS with quadratic indifference is formulated. Finally a step by step procedure for implementing a PASS plan is presented along with an example.     

NMR法表征PASS及PASS/NMP溶液结晶过程

用1H-NMR和13C-NMR核磁共振技术研究了聚芳硫醚砜(PASS)的结构,并通过13C-1H异核相关谱提供的信息确定了其1H谱和13C谱中各谱峰的归属,为聚合物的表征提供了依据。并通过1H-NMR对比了PASS与N-甲基吡咯烷酮(NMP)溶液结晶过程前后的结构变化。     

聚芳硫醚砜纳米纤维直径的影响因素及其控制

针对制备条件对聚芳硫醚砜纳米纤维直径大小的影响,文中设计了正交实验,集中考察了溶液浓度、环境温度、应用电压、喷嘴到收集屏的距离和流量五种因素对静电纺丝制备聚芳硫醚砜纳米纤维的影响,结果表明,溶液浓度对纳米纤维直径的影响最大,可通过调整溶液的浓度及黏度来控制所制备的纳米纤维直径。     

Type I Collagen Immobilized Poly(caprolactone) Nanofibers: Characterization of Surface Modification and Growth of Fibroblasts

Poly(caprolactone) (PCL) electrospun nanofibers were modified by aminolysis and collagen was immobilized on the aminolysed PCL nanofibers. Considering low immunogenic response collagen elicits, immobilization of the same is anticipated to enhance the tissue engineering application of the PCL nanofibers. Amino groups were introduced into PCL nanofibers through aminolysis process. Aminolysis of PCL nanofibers was confirmed by electron dispersive X‐ray analysis (EDX). Collagen was immobilized on aminolysed PCL nanofibers using glutaraldehyde as crosslinker. The collagen crosslinking on to PCL nanofibers was established by attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR) spectroscopy. The fiber morphologies of PCL nanofibers at different stages were characterized by scanning electron microscopy (SEM). The change in hydrophobicity of PCL nanofibers due to aminolysis and collagen immobilization was determined by water contact angle measurements. Aminolysis followed by collagen immobilization had reduced the intrinsic hydrophobicity of PCL nanofibers. NIH 3T3 fibroblasts were cultured for 2 days on PCL nanofibers, aminolysed PCL nanofibers, and aminolysed PCL nanofibers crosslinked with collagen. Cell attachment and growth were observed by MTT assay in each case. Collagen immobilization improved the biocompatibility of the PCL nanofibers. Thus the modified PCL nanofibers can be used as suitable broad spectrum scaffold for skin, cartilage, bone, cardiac constructs for efficient tissue engineering applications.     

炭纤维网布/螺旋碳纤维复合材料制备及电磁性能研究

以炭纤维网布为基体,通过电镀工艺在炭纤维网布上形成Ni催化剂膜,采用化学气相沉积方法原位合成炭纤维网布/螺旋纳米碳纤维复合材料,采用扫描电镜(SEM)、Raman光谱和X射线衍射仪(XRD)对生长的螺旋纳米碳纤维的形态和结构进行表征。考察主要反应因素—温度对螺旋纳米碳纤维生长的影响,并就生长过程进行了讨论;对其制备出的炭纤维网布/螺旋纳米碳纤维复合材料在8.2～12.4GHz频段的电磁性能进行分析,考察其吸波性能。结果表明制备出的炭纤维网布/螺旋纳米碳纤维复合材料比单一的螺旋纳米碳纤维具有更高的电磁损耗角正切,电损耗正切值由0.7提高到3.8,表明复合材料具有较好的吸波性能。     

Preparation and electrical characterization of polyamide-6/chitosan composite nanofibers via electrospinning

We report on the preparation and electrical characterization of polyamide-6/chitosan composite nanofibers. These composite nanofibers were prepared using a single solvent system via electrospinning process. The resultant nanofibers were well-oriented and had good incorporation of chitosan. Current-voltage (I-V) measurements revealed interesting linear curve, including enhanced conductivities with respect to chitosan content. The electrical conductivity of the polyamide-6/chitosan composite nanofibers increased with increasing content of chitosan which was attributed to the formation of ultrafine nanofibers. In addition, the sheet resistance of composite nanofibers was decreased with increasing chitosan concentration.     

Fiber template approach toward preparing one-dimensional silica nanostructure with rough surface

Silica nanofibers were grown on the surface of chitosan nanofibers used as templates by coating the surface with silica derived from the hydrolysis and condensation of tetraethoxysilane using ammonium hydroxide as a catalyst. This was followed by the decomposition of the chitosan template. The relationship between different processing factors (type of templates as well as amounts of catalyst and template) and the formation of silica nanofibers was examined. Varying the processing factors was found to be effective in controlling the morphology of the silica nanofibers. The use of chitosan nanofibers effectively led to the formation of one-dimensional silica nanofibers as the positively charged chitosan nanofibers promoted the deposition of the negatively charged silica nanoparticles through electrostatic attractive forces. Therefore, the chitosan nanofibers acted as good deposition sites for interacting with silica nanoparticles. Although a large amount of catalyst promoted the sol-gel reaction, the silica nanoparticles grew excessively in the solvent. Therefore, the surface structure of the prepared silica nanofibers could be controlled by varying the amount of chitosan template as this also varied the formation mechanism of the silica nanofibers. The resultant samples had a rough silica wall composed of densely assembled silica nanoparticles, with a high specific surface area (338 m²/g).     

Electrospun nanofibers of collagen-chitosan and P(LLA-CL) for tissue engineering

Electrospun nanofibers could be used to mimic the nanofibrous structure of the extracellular matrix (ECM) in native tissue.In tissue engineering,the ECM could be used as tissue engineering scaffold to ...     

Mechanical Properties,Morphologies, and Microstructures of Novel Electrospun Metallized Nanofibers

We report that the metal‐deposited single nanofibers can be successfully prepared by electrospinning and metallization. The tensile strength of the metal‐deposited single nanofibers as well as various non‐metallized polymeric nanofibers was investigated by recently developed tensile test machine. The tensile strength of 50 nm metal‐deposited single nanofibers was dramatically improved, which was much higher than that of pure polymer single nanofiber. The result is attributed to the formation of metallic hard‐coating layers onto the surface of single nanofibers. The tensile strength of the metal‐deposited single nanofibers was also depended on the types of metals (for instance, Cu, Ni, Sn, and Al) used for metallization. In addition, we investigated various annealing conditions, such as annealing temperature and time, and composition ratio of two metals (Cu and Ni), in order to find out optimum annealing process for the formation of metal alloy nanofibers. The characterization of the metallized nanofibers was conducted by field emission scanning electron microscope (FE‐SEM) and X‐ray diffraction (XRD).