熔体直写电纺聚己内酯纤维有序沉积工艺

目前聚合物熔体电纺技术制备的纤维大多以杂乱无序的无纺布形式存在,限制了电纺技术在组织工程支架以及机器人等需要有序结构领域的应用。本文将熔体电纺技术与三维运动平台相结合,采用自主设计的熔体电纺可控成型实验装置,对聚己内酯（PCL）进行熔体直写静电纺丝,获得了有序纤维。研究了喷头移动速度、接收距离和纺丝电压对熔体直写电纺纤维沉积形貌的影响。结果表明,纤维直径随着喷头移速、接收距离和纺丝电压的增大而减小,其中接收距离的改变对直径的影响最为显著;接收距离的增大虽然有利于纤维的细化,但是距离过大会使纤维沉积的有序性变差;当射流下落速度与喷头移动速度相匹配时,射流才能实现有序沉积;增大接收距离和纺丝电压会引起射流鞭动,需要相应地增大喷头移动速度才能实现有序沉积。     

静电纺间位芳纶纳米纤维的制备工艺参数

通过静电纺丝方法,将氯化锂/N,N–二甲基乙酰胺(Li Cl/DMAc)溶解间位芳纶(PMIA)制备了PMIA纳米纤维,探索了溶液浓度、接收距离、纺丝电压及接收速度等工艺参数对纤维形貌及其直径分布的影响。通过扫描电子显微镜观察了PMIA纳米纤维形貌及应用Image-J软件测量统计了PMIA纤维直径。结果表明,溶液浓度为8%~10%、纺丝电压为16~18 k V、接收距离为15~20 cm,接收速度60~80 r/min的范围内,间位芳纶纳米纤维成型良好,直径分布范围为100~120 nm;PMIA纳米纤维直径随着溶液浓度的减小、静电电压的增加而减小,随着接收速度的增加纤维取向增加。     

激光熔融静电纺丝PA6纤维的制备及表征

采用激光熔融静电纺丝法制备了聚已内酰胺(PA6)微纳米纤维和PA6/乙烯-乙烯醇共聚物(PA6/EVOH)复合纤维;研究了接收距离、应用电压和激光电流对PA6纤维直径的影响;并对PA6纤维的结构与性能进行了表征。结果表明:在接收距离13 cm,应用电压23 kV,激光电流35 mA,进料速度7.39 mm/min时,可得到PA6纤维的最小平均直径为1.62μm,与纯PA6纤维相比,PA6/EVOH复合纤维平均直径明显变小,达1.11μm;接收距离与PA6纤维直径之间没有明显的关系;应用电压在12～15 kV时,PA6纤维直径明显下降,在15～24 kV时,PA6纤维的平均直径变化不大;PA6纤维直径随激光电流的增加而减小;红外光谱分析及X射线衍射测试表明,激光熔融静电纺丝PA6纤维的分子链结构没有改变,PA6纤维中存在γ晶型,结晶度为48.7%、     

静电纺丝工艺对二醋酸纤维素纳米纤维形貌及直径的影响

以质量比为2∶1的丙酮/N,N-二甲基乙酰胺混合溶液为溶剂配制二醋酸纤维素(CA)溶液,采用静电纺丝制备CA纳米纤维,探讨了CA浓度、纺丝电压、接收距离和溶液推进速度等工艺条件对CA纳米纤维形貌、直径及其分布的影响。结果表明:CA纳米纤维的直径随CA浓度增加而增大,随纺丝电压增大而减小;适当的接收距离和溶液推进速度可以获得直径较小且分布均匀的纤维;当CA质量分数为11%、纺丝电压为30 k V、接收距离为15 cm、溶液推进速度为0.010 m L/min时,纺丝效果好,纤维平均直径约130 nm,且直径分布较均匀。     

气流-静电纺丝法制备聚对苯二甲酸乙二酯纳米纤维

采用50%苯酚和50%1,1,2,2-四氯乙烷的混合溶液为溶剂,通过气流-静电纺丝法制备了聚对苯二甲酸乙二酯(PET)纳米纤维。利用扫描电镜(SEM),研究了聚合物分子质量、溶液浓度、电压、接收距离(喷丝孔到接收板的距离)对电纺纤维形态结构的影响。结果表明:随着聚合物分子质量和溶液浓度增加,纤维平均直径也随之增加;纤维平均直径随电压的增加而减小;随接收距离的增加,纤维平均直径先减小后增加。最佳工艺条件为:聚合物特性黏度为0.818 dL/g,溶液质量分数为15%,电压为32 kV,接收距离为23 cm,所得PET电纺纳米纤维平均直径为85 nm。     

静电纺PCL纤维形态与热性能的研究

利用静电纺丝法制备了超细聚ε-己内酯(PCL)纤维;借助扫描电镜仪和差示扫描量热仪表征了PCL纤维的形态与热性能;研究了电纺过程中溶液浓度、电压、接收距离和纺丝速度对纤维形态的影响。结果表明:当纺丝电压为10 kV,接收距离为15 cm,纺丝速度为2 mL/min时,纺丝液中PCL质量分数为6%~12%能获得连续无串珠的纤维;纺丝电压为8~12 kV,电纺过程稳定;接收距离对纤维的直径和形貌无明显影响;与流延成型的PCL膜相比,电纺PCL纤维具有较低的结晶度。     

熔体静电纺丝的电场分布及其对PET纤维成形的影响

借助ANSYS软件模拟聚对苯二甲酸乙二酯(PET)熔体静电纺丝在不同参数(纺丝电压、接收距离、接收板面积)条件下的电场分布,探讨电场分布对熔体静电纺丝PET射流运动与纤维形貌的影响。结果表明,在单喷嘴–平板结构模型中,提高纺丝电压将增强整体空间电场强度,使电场对PET熔体射流的控制力加强,PET熔体射流的摆动半径减小,当纺丝电压由24 k V升高到30 k V时,摆动半径由11.7 mm减至9.9 mm,而摆动角增大,由10.1°增至11.2°,PET纤维直径显著减小,由3.275μm减至2.202μm;接收距离的改变对接收板表面电场的影响显著,随着接收距离的增加,PET射流的直线段比例明显下降,当接收距离由50 mm增加至90 mm时,PET熔体射流的直线段比例由68.0%减至54.0%,PET纤维直径在适中接收距离(70 mm)下表现较细,可达2.184μm;接收板面积的减小加强了对PET熔体射流的控制,使PET熔体射流直线段比例显著增加,当接收板面积由15 cm×15 cm减小至10 cm×10 cm时,PET熔体射流直线段比例由68.0%增加至82.6%,摆动半径减小,由9.9 mm减至4.2 mm,沉积角因PET熔体射流贴服接收板而减小,由12.2°减至9.1°,PET纤维直径稍有增加,由2.202μm增加至2.537μm。     

静电纺丝法纺制聚乳酸纳米纤维无纺毡

采用静电纺丝法制备了生物降解聚乳酸(PLLA)纳米纤维无纺毡。分析了纺丝液浓度、电压、接收距离、挤出速度等因素对纤维形态的影响。结果表明:纺丝液的浓度和挤出速度对纤维直径的影响较为明显,溶液挤出速度增大,所得纤维微孔含量及尺寸也增大;适当的电压和接收距离有利于收集无液滴纤维;随着纤维直径的减小,无纺毡的孔径呈减小趋势。在PLLA质量分数为5．7％、挤出速度0．8 mL／h、接受距离 15．5 cm、电压8 kV的静电纺丝条件下,可制备纤维直径为200-400 nm的PLLA纳米纤维无纺毡。     

气流-静电纺丝法制备苯乙烯—丁二烯—苯乙烯嵌段共聚超细纤维

采用75%四氢呋喃(THF)和25%N,N-二甲基甲酰胺(DMF)的混合溶液作溶剂,通过气流-静电纺丝法制备了苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)超细纤维。利用扫描电镜(SEM),研究了溶液浓度、电压、接收距离(喷丝孔到接收板的距离)、喷丝孔内径对静电纺纤维的直径和形貌的影响。研究发现:溶液浓度对电纺纤维的直径和形貌有非常重要的影响,当溶液浓度由10%增加到18%时,电纺纤维平均直径随之成线性增加;当电压由23.8kV增加到33.8kV时,纤维平均直径先减小后增加。最佳工艺条件为:溶液质量分数为14%,电压为28.8kV,接收距离为20cm,喷丝孔内径为0.27mm,所得SBS电纺超细纤维平均直径为429nm。     

聚醚砜的静电纺丝研究

采用聚醚砜(PES)的良溶剂二甲基甲酰胺(DMF)和非良溶剂丙酮(AC)为共溶剂体系,研究了溶剂组成、纺丝成形条件对静电纺丝PES纤维的形貌及纤维直径的影响。结果表明:DMF/AC的配比对于静电纺丝PES纤维形貌具有直接的调控作用,随着DMF/AC混合溶剂中AC用量的增加,纤维平均直径变大,纤维毡中串珠数目明显减少,纤维均一性变好;随着纺丝液浓度的升高,纺丝电压的增大,纤维的平均直径变大;接收距离的变化对纤维平均直径影响不大;PES最佳纺丝工艺条件为纺丝溶液质量分数13%,纺丝电压15 kV,接收距离10 cm,mDMF/mAC为8.5/1.5,在此条件下,可以获得纤维平均直径为96 nm的PES纤维毡。     

Double‐nozzle air‐jet electrospinning for nanofiber fabrication

A novel double‐nozzle air‐jet electrospinning apparatus was developed to fabricate nanofibers on a large scale. The distribution of the electric field at different nozzle distances was simulated to analyze the jet path, productivity, and deposition area of nanofiber webs and the nanofiber morphology. Our experiments showed that the bubbles usually ruptured intermittently on the top surface of the two nozzles and the jets traveled in a straight path with a high initial velocity. A continuous and even thickness of the nanofiber webs were obtained when the nozzle distances was less than 55 mm. At nozzle distances of 55 mm, the received fibers were thin with the lowest standard deviation. Experimental parameters involving the applied voltage, collecting distance, and air flow rate were also investigated to analyze the nanofiber morphology at a nozzle distance of 55 mm. The results show that the nanofibers presented a finer and thinner diameter at an applied voltage of 36 kV, a collecting distance of 18 cm, and an air flow rate of 800 mL/min. The nanofiber production of this setup increased to nearly 70 times that with a single‐needle electrospinning setup. On the basis of the principle of this air‐jet electrospinning setup, various arrangements of multinozzle electrospinning setups could be designed for higher throughput of nanofibers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40040.     

Solution blow spinning: A new method to produce micro‐ and nanofibers from polymer solutions

A solution blow spinning technique was developed using elements of both electrospinning and melt blowing technologies as an alternative method for making non‐woven webs of micro‐ and nanofibers with diameters comparable with those made by the electrospinning process with the advantage of having a fiber production rate (measured by the polymer injection rate) several times higher. The diameters of fibers produced ranged from 40 nm for poly(lactic acid) to several micrometers for poly(methyl methacrylate). This solution blow spinning method uses a syringe pump to deliver a polymer solution to an apparatus consisting of concentric nozzles whereby the polymer solution is pumped through the inner nozzle while a constant, high velocity gas flow is sustained through the outer nozzle. Analysis of the process showed that pressure difference and shearing at the gas/solution interface jettisoned multiple strands of polymer solution towards a collector. During flight, the solvent component of the strands rapidly evaporates forming a web of micro and nanofibers. The effect of injection rate, gas flow pressure, polymer concentration, working distance, and protrusion distance of the inner nozzle was investigated. Polymer type and concentration had a greater effect on fiber diameter than the other parameters tested. Injection rate, gas flow pressure, and working distance affected fiber production rate and/or fiber morphology. Fibers were easily formed into yarns of micro‐ and nanofibers or non‐woven films that could be applied directly onto biological tissue or collected in sheets on a rotating drum. Indeed, virtually any type of target could be used for fiber collection. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

工艺参数对静电纺PPESK微纳米纤维膜性能的影响

通过溶液静电纺丝法制备了聚芳醚砜酮(PPESK)微纳米纤维膜,借助于扫描电子显微镜和拉伸试验机分别对纤维膜的形貌和力学性能进行了表征,用正交试验对微纳米纤维膜的制备工艺参数进行了优化。结果表明,在给定条件下,对纤维直径影响由大到小的工艺参数依次为:溶液浓度给料速度纺丝电压。纤维直径最小的工艺条件为:溶液浓度19%,纺丝电压10 k V,给料速度为0.04 mm/min。对纤维膜拉伸强度影响由大到小的工艺参数依次为:给料速度纺丝电压溶液浓度。纤维拉伸强度最大的工艺条件为:溶液浓度24%,纺丝电压14 k V,给料速度0.04 mm/min。     

The effects of processing parameters on the morphology of PLA/PEG melt electrospun fibers

Electrospinning of a polymer melt is an ideal technique to produce highly porous nanofibrous or microfibrous scaffolds appropriate for biomedical applications. In recent decades, melt electrospinning has been known as an eco‐friendly procedure as it eliminates the cytotoxic effects of the solvents used in solution electrospinning. In this work, the effects of spinning conditions such as temperature, applied voltage, nozzle to collector distance and collector type as well as polyethylene glycol (PEG) concentration on the diameter of melt electrospun polylactic acid (PLA)/PEG fibers were studied. The thermal stability of PLA/PEG blends was monitored through TGA and rheometry. Morphological investigations were carried out via optical and scanning electron microscopy. Based on the results, blends were almost stable over the temperature range of melt electrospinning (170 ? 230 °C) and a short spinning time of 5 min. To obtain non‐woven meshes with uniform fiber morphologies, experimental parameters were optimized using ANOVA. While increasing the temperature, applied voltage and PEG content resulted in thinner fibers, PEG concentration was the most influential factor on the fiber diameter. In addition, a nozzle to collector distance of 10 cm was found to be the most suitable for preparing uniform non‐woven PLA/PEG meshes. At higher PEG concentrations, alterations in the collector distance did not affect the uniformity of fibers, although at lower distances vigorous bending instabilities due to polarity augmentation and viscosity reduction resulted in curly fibrous meshes. Finally, the finest and submicron scale fibers were obtained through melt electrospinning of PLA/PEG (70/30) blend collected on a metallic frame. © 2017 Society of Chemical Industry     

Deposition of Particles by a Confined Impinging Jet onto a Flat Surface at Re = 10 4

An axisymmetric turbulent air jet flow (with vertical and downward orientation) laden with fluorescent solid particles was impinged normally onto a flat surface. The particle deposition efficiency and distribution on the flat surface were measured experimentally using fluorometry and imaging techniques. The fluorescent particles (5.0 μm diameter) were dispersed by a nebulizer and injected in a stream of compressed air, resulting in a steady flow (Q = 111 L/min). A round nozzle was used to generate a jet characterized by a Reynolds number of Re = 10 ⁴ , based on the nozzle diameter (D = 15.0 mm) and nozzle exit velocity (u = 10.5 m/s). Three dimensionless distances from the nozzle's exit to the impaction surface, L/D = 2, 4, and 6, were investigated. It was observed that although having similar total deposition efficiencies (16.5–17.8%), shorter nozzle to surface distances (L/D = 2 and 4) show a more pronounced ring-like radial deposition pattern around the stagnation point. These shorter distances also exhibit significantly lower particle deposition near the stagnation point when compared to the longer distance (L/D = 6). Indeed, in moving through L/D = 2, 4, and 6, peak deposition density values of 254, 347, and 685 particles/mm ² shift through radii of 2.1 D, 0.8 D, and 0.1 D, respectively. In addition to the experiments, numerical simulation was also performed, which showed that the particle deposition was dominated by a turbulent dispersion mechanism for L/D = 2, with inertial impaction becoming more important for the L/D = 4 and 6 cases.     

Effect of experimental parameters on needleless electrospinning from a conical wire coil

In this study, a conical wire coil was used as spinneret to launch a novel needleless electrospinning. Multiple polymer jets were observed on the surface of the coil in the electrospinning process. Productivity of the nanofibers can be enhanced to >2.5 g/h by using this novel nozzle. The fiber productivity and diameter together with diameter distribution were dependent on the concentration of the polymer solution, applied voltage, and collecting distance. This novel concept of using wire coil as the electrospinning nozzle depicts a model of large‐scale needleless electrospinning system for nanofiber production. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Optimization of Process-Control Parameters for the Diameter of Electrospun Hydrophilic Polymeric Composite Nanofibers

A composite nanofiber composed of three polymers, namely polyvinyl alcohol/polyvinyl pyrrolidone/polyethylene oxide, is produced. The experiments are constructed using three design of experiment techniques, Taguchi L₉, Taguchi L₂₇, and Screening method. The experiments are verified using the analysis of variance (ANOVA) method and later a mathematical model is developed using the regression method. The impact of electrospun processing parameters, namely applied voltage, flow rate, and working distance, on nanofibers' diameter is measured. The working distance is a significant factor in controlling the size of the fiber diameter, while the applied voltage has the lowest effect on it. As a result of the regression equation, a Genetic algorithm is used to find the optimum variables for the required fiber diameter, which is 156 nm for flow rate = 0.001 mL h⁻¹, voltage = 30 kV, and distance = 200 mm with a 3% difference from the experimental fiber diameter.