Effect of electrospinning parameters on piezoelectric properties of electrospun PVDF nanofibrous mats under cyclic compression

The high piezoelectric response capacity of electrospun PVDF nanofibers is currently a challenging area of research, and this study attempts to optimize the piezoelectric properties of electrospun PVDF nanofibrous mat under controlled electrospinning process. Some experiments were designed to study the relationship between electrospinning processing parameters and the piezoelectric properties of PVDF mats under cyclic compression, and this relationship was compared with the change of crystalline structure features with the electrospinning parameters. The excitation method is based on low velocity compression test by cyclically pressing flat contactor on samples. The impact of each of processing parameters has been investigated. It was found that three electrospinning parameters including: applied voltage, feeding volume flow rate and syringe needle tip diameter, are significant influential factors to the piezoelectric properties of the electrospun PVDF nanofibrous mats. However, the feeding volume flow rate has a greater effect on the piezoelectric responses to cyclic compression than both applied voltage and volume flow rate does, and its effect on the piezoelectric responses is different from that of β-phase fraction of crystalline structure within PVDF nanofiber. It was also observed that the relationship between the piezoelectric peak intensity and the applied voltage as well as the feeding volume flow rate is nonlinear.     

Preparation and characterization of EPDM ultrafine fibers by electrospinning

Ethylene-propylene-diene monomer (EPDM) ultrafine fibers have been prepared by electrospinning method, with an average diameter of micron grade and fibrous structural morphology. The effects of experimental parameters, including the solution concentration, applied voltage, collection distance, and flow rate, were investigated carefully. It shows that the morphology and fiber diameter of electrospun EPDM fibers are greatly influenced by the process parameters. Fourier transform infrared, X-ray diffraction, and differential scanning calorimetry apparatuses were used to analyze the structural and thermal properties of the electrospun fiber mat, with EPDM cast film as a comparison. The results reveal that the electrospun fiber mat has a lower degree of crystallinity than its cast film.     

Influence of solution and processing parameters towards the fabrication of electrospun zein fibers with sub-micron diameter

The effects of processing and solution parameters on the morphology of food grade electrospun fibers were investigated. The relationship of entanglement concentration (C_e) of zein solution and its electrospinnability was inspected to determine the correlation of fiber morphology with the rheology of solutions. Bead-free and uniform zein electrospun fibers were successfully constructed. Response surface methodology (RSM) was utilized to facilitate a more systematic understanding of the electrospinning parameters of zein solutions. The electrospinning parameters studied were concentration of zein solution, solution feed rate, applied voltage and distance between needle tip and collector. The individual and interaction effects between the parameters on average diameter of the electrospun fibers were determined using Box and Behnken factorial design. The interaction effect between feed rate and voltage, the quadratic coefficients of the applied voltage as well as linear coefficients of the solution concentration, voltage and feed rate were found statistically significant in the fabrication of sub-micron fibers. Hence, this work provides an overview on the impact of solution and processing parameters to the fabrication of zein electrospun fibers which may find uses as nanostructured materials in food industry.     

丝素与明胶共混静电纺丝

 丝素和明胶以不同质量比共混于甲酸溶剂,将此纺丝液进行静电纺丝,并用扫描电镜观察其形态结构,分析探讨了工艺参数对其形貌和直径的影响,并与相同工艺条件下的纯丝素纳米纤维进行比较。结果表明:在丝素与明胶质量比为70∶30,纺丝液质量分数为11%,极距为13 cm,电压为22 kV的工艺条件下,静电纺纤维平均直径为83.9 nm,纤维直径分布均匀。用明胶共混不仅有利于克服低质量分数丝素纺丝液静电纺丝中出现的珠状物和断头多等问题,而且有望应用于生物组织工程中。     

静电纺参数对二醋酸纳米纤维直径分布的影响

为研究二醋酸纳米纤维工艺参数对其直径分布的影响,采用静电纺丝技术制备纳米纤维,对影响纳米纤维形貌的纺丝液质量分数、纺丝距离、电压及纺丝速度等参数进行探讨,对实验工艺进行优化,确定实验最佳参数。借助扫描电镜对制备的纳米纤维形貌进行观察,并应用Photoshop CS 3.0软件对纤维直径进行测量统计。结果表明,纺丝液质量分数、纺丝速度、纺丝距离对纳米纤维直径的影响较为显著,而纺丝电压对纳米纤维直径的影响相对较小。     

静电纺纤维结构研究进展

通过调整纺丝溶液性质、改变纺丝过程中的加工参数、改进纺丝装置以及结合相应的后处理工艺,可以改变采用静电纺丝技术获得的纤维的结构,包括纤维集合体的结构和单纤维的结构,而纤维结构的改变对扩大纤维应用领域及增强纤维应用性能具有重要作用.综述了近年来静电纺丝技术发展过程中出现的一些新颖的纤维结构,并展望了静电纺纤维结构调控的发...     

PVDF静电纺纤维毡表面电性能

研究静电纺丝过程中纺丝液的质量浓度和性质、施加电压的极性和施加方式对所得聚偏二氟乙烯（PVDF）超细纤维微观形貌、纤维直径和纤维毡表面电性能的影响,并考察采用静电纺丝方法制备PVDF驻极体的可行性。结果表明：静电纺丝所得PVDF纤维毡表面有一定量的电荷残留,其电荷残留量与纺丝原液质量浓度成正比,但残留电荷很快耗散,不能直接用来制备驻极体;对比发现不同介电常数的接收介质（如：锡箔,非织造布,塑料薄膜等）对静电纺丝纤维毡表面电势残留有直接的影响。     

静电纺短纤维的制备及其生物医学应用

传统静电纺纳米纤维常作为组织工程支架被用于修复缺损部位,往往必须借助外科手术有创植入,极大限制了其在生物医学领域中的应用。为促进静电纺丝技术的开发和应用,综述了静电纺短纤维的制备及其功能化的方法,分类介绍了功能化短纤维在诊断检测、治疗和组织工程这3个方面的生物医学应用;系统分析通过调节工艺参数、后续加工等方式保留静电纺纳米纤维膜的内在功能,以及基于其小尺寸和单分散性,避免纤维膜植入所造成的机体侵入创伤;最后,结合静电纺短纤维当前发展情形分析了其在生物医学领域应用中所面临的挑战和未来的发展前景。     

制备纳米纤维的静电纺丝接收器研究进展

静电纺丝是制备纳米纤维的重要方法,在众多领域具有较强应用价值,引起广泛关注。所得纳米纤维的取向和结构对其性能有重要影响,近年来研究主要集中于如何获得结构不同、形态各异的电纺纤维材料,以满足不同领域的使用要求。接收器作为静电纺丝装置的重要部分,决定电纺纤维的分布与组合。目前,通过对接收器进行改进已经能够制备三种基本结构电纺纤维材料,分别是排列规则纳米纤维线、图案化纳米纤维膜和三维纳米纤维体。本文简述静电纺丝原理,分别对比三种类型纳米纤维结构制备中所采用的不同接收器结构特点和收丝效果。该综述可供纳米纤维材料制备、静电纺丝装置改进和静电纺丝技术应用等研究参考。     

电压对静电纺串珠纤维成形过程的影响

以聚苯乙烯为原材料,观察在不同电压条件下以及射流不同区域的串珠纤维,研究电压对串珠形态、纤维运动速度的影响以及串珠形态在射流过程中的演变。采用高速摄影,显微镜对射流过程以及纤维形态进行表征。运用有限元仿真软件对电场、串珠形貌和串珠纤维运动速度进行模拟,建立串珠模型。研究结果表明：纺丝电压增大,射流受到的拉伸作用更明显,串珠形态逐渐由近似圆形变为纺锤形,同时串珠的表面速度也随着电压的增大而增大,实验结果与仿真模拟结果一致;射流直线段并未出现串珠结构,串珠在鞭动区域逐步形成,同时,在越靠近接收装置的射流区域,串珠纤维受到的拉伸作用越明显。     

氯化锂对静电纺PVA溶液稳定段射流的影响

静电纺丝过程中,当溶液完全绝缘或施加电压不够高时,静电力不能克服溶液的表面张力,纺丝无法进行。为克服这个问题,在溶液中加入盐。用聚乙烯醇纺丝液,当添加的LiCL质量分数不同时,纺得的纳米纤维直径从大到小排列顺序为：1% LiCl>0.8% LiCl>0.5% LiCl>0.2% LiCl。研究了LiCl质量分数对于轴向坐标的射流半径的影响机制,推导出直线段（稳定段）部分射流半径与轴向坐标符合如下关系, 的关系,并通过测量添加不同质量分数LiCl的聚乙烯醇纺丝液的射流半径进行实验验证,结果表明实验值与理论值完全吻合。     

Nanotechnology in fibrous materials-a new perspective

This issue reviews various areas where nanotechnology has come up predominately in fibrous materials, namely in electrospun polymeric nanofibers and polymer layered silicate nanocomposites. It includes synthesis, characterization, various methods of collecting nanofibers, factors affecting electrospinning, methods of increasing the productivity of the electrospinning process, and different electrospinning designs. It also covers synthesis and characterization of polymer nanocomposites. Various properties of nanocomposites are discussed. The rheological behavior and morphology of nanocomposites are covered. Different modeling and simulation methods applicable to electrospun nanofibers and polymer layered silicate nanocomposites are discussed. Some of the potential application areas of electrospun nanofibers, polymer layered silicate nanocomposites, and various products available in the market based on nanotechnology are also discussed. Some of the lacking areas and future prospects in nanofibrous structures (nanofibers and nanocomposites) are emphasized in this issue.     

静电纺聚砜纤维膜对分散染料的过滤性能研究

采用静电纺丝法制得聚砜纤维膜,并用其过滤分散艳蓝2BLN染液.研究了静电纺聚砜纤维膜的表面形态、孔隙结构及其对分散艳蓝2BLN的过滤性能.结果表明,静电纺聚砜纤维膜对分散艳蓝2BLN的过滤效率几乎为零.     

Nanotechnology in fibrous materials–a new perspective

This issue reviews various areas where nanotechnology has come up predominately in fibrous materials, namely in electrospun polymeric nanofibers and polymer layered silicate nanocomposites. It includes synthesis, characterization, various methods of collecting nanofibers, factors affecting electrospinning, methods of increasing the productivity of the electrospinning process, and different electrospinning designs. It also covers synthesis and characterization of polymer nanocomposites. Various properties of nanocomposites are discussed. The rheological behavior and morphology of nanocomposites are covered. Different modeling and simulation methods applicable to electrospun nanofibers and polymer layered silicate nanocomposites are discussed. Some of the potential application areas of electrospun nanofibers, polymer layered silicate nanocomposites, and various products available in the market based on nanotechnology are also discussed. Some of the lacking areas and future prospects in nanofibrous structures (nanofibers and nanocomposites) are emphasized in this issue.     

静电和熔融纺丝法对PET纤维表面结构的影响

采用扫描电子显微镜(SEM)、原子力显微镜(AFM)和差示扫描量热仪(DSC)对溶液和熔融静电纺丝法所制备的PET纤维,以及工业熔融纺PET纤维的表面形貌和热学性能进行分析比较.结果表明,因加工成纤方式不同,熔融静电纺纤维表面光滑匀整,工业熔融纺纤维表面有明显的凹凸波浪纹,而溶液静电纺纤维表面略显蜂窝状结构.由DSC分...     

静电纺聚乳酸纤维毡的微观结构及力学行为

通过静电纺丝可以制备由直径为数微米的聚乳酸纤维构成的多孔状材料。在确定纺丝工艺条件的基础上,分析接收基底对PLA纤维毡微观结构和力学性能的影响。研究结果表明:质量分数为11%的聚乳酸/二氯甲烷溶液可以利用静电纺纺出连续光滑且比较均匀的纤维;当以纳米级的静电纺丝素或锦纶纤维毡为基底时,可以使PLA纤维的分布均匀化,同时纤维的直径下降;经过复合后,PLA复合纤维毡承受负荷的能力得到了很大提高。     

静电纺丝技术在食品领域应用的研究进展

由于活性肽、精油及益生菌等生物活性物质易受热、光、加工和储运等外界因素的影响,如何使生物活性物质不受上述条件制约,并保持其活性已成为食品加工技术研究热点。静电纺丝技术因具有操作简便、生物活性物质包封效率高、包封过程中不产生热量、被包封物质易于释放等优点,在食品领域应用的研究日益增多。本文主要介绍了静电纺丝技术的原理、常用的包封材料、静电纺丝纤维形态的影响因素、静电纺丝技术在食品领域中的应用和展望。建议未来研究的重点主要放在开展静电纺丝无毒专用包封材料的筛选,静电纺丝纤维包封生物活性物质的体内靶向释放及其功能性评价,以及实现静电纺丝纤维的工业化连续生产上。     

Electrospraying and Electrospinning of Chocolate Suspensions

Novel applications of efficient and economical techniques such as electrospraying and electrospinning in chocolate processing could be a strategy to help manufacturers improve declining sales growth rate in a saturated confectionery market. In this study, electrosprayed near-monodisperse particles have been produced using chocolate suspensions. Electrospun fibres have also been created from a commercial chocolate sauce. The effects of process parameters such as sugar concentration, addition of electrolytes (NaCl), flow rate, applied voltage and collection distance on the production and morphology of as-sprayed chocolate particles were studied. A positive linear trend in the electrosprayed chocolate particle diameter and diameter distribution range with increasing sugar concentration in the chocolate suspension was demonstrated. Sugar concentrations of 30–35%w/w resulted in very fine, near-monodisperse chocolate particles. Trace amounts of electrolyte at 1%w/w were found to decrease the average particle diameter and improve the monodispersity of the particles produced. The addition of NaCl at low concentrations increased the electrical conductivity and, to a lesser extent, the surface tension of the chocolate samples. Further increases in NaCl concentration to 3%w/w did not bring any additional decrease in the average diameter of the chocolate particles. In addition, the observed modes of electrospraying and the characteristics of chocolate particles obtained under these were investigated. Bead-on-string morphology was commonly observed among electrospun chocolate fibres. Moreover, satellite particles and very fine fibres were obtained during the transition between electrospraying and electrospinning. The continuous alternating shape of elongated spheres and thin fibres may have the potential for varying the microtexture of the chocolate products.     

二甲基亚砜/水溶液体系中氢键对静电纺淀粉纤维的影响

为探究氢键对静电纺淀粉纤维膜的影响,以二甲基亚砜/水为溶剂体系对淀粉进行溶解制备静电纺纤维膜。通过调节二甲基亚砜/水体系中含水量,诱导水分子与淀粉分子链上的羟基结合形成氢键,研究氢键对淀粉溶解及淀粉纤维成型的影响。通过扫描电子显微镜、红外光谱、差热分析、X线衍射及拉伸实验等对静电纺淀粉纤维的表面形貌、结构和力学性能进行表征。结果表明：二甲基亚砜破坏了淀粉分子中的氢键,有利于淀粉的溶解;随着二甲基亚砜/水体系中含水量的增加,水与淀粉分子链中的羟基形成了氢键。氢键的形成会对淀粉纤维产生影响,一方面,氢键的形成使得淀粉纺丝液的可纺性变差,纤维形貌变得不均一;另一方面,对于静电纺纤维膜而言,过多的水会与淀粉分子形成氢键,抑制分子链的自由移动,导致纤维膜的断裂强度提高,断裂伸长率下降。     

静电纺聚氨酯纳米纤维非织造布的制备

研究了聚氨酯在几种常见有机溶剂中的溶解性能,寻求静电纺丝最佳溶剂及配比,并采用静电纺丝法制备纳米级聚氨酯纤维膜。通过改变共混溶剂的质量比、纺丝液的浓度、纺丝电压、挤出速度和接收距离,借助扫描电子显微镜测量纤维的直径,分析了各因素对纤维形貌结构的影响。结果表明:DMF/THF共混溶剂配比为1:3时,聚氨酯纺丝液静电纺丝效果佳;在纺丝液浓度8%～12%、纺丝电压12～30kV、接收距离10～30cm范围内,能纺制出纤维直径分布在800～1500nm之间的聚氨酯纳米纤维非织造布。