静电纺丝法制备聚碳酸酯基聚氨酯纳米纤维的研究

以N,N-二甲基甲酰胺(DMF)和四氢呋喃(THF)为混合溶剂配制聚碳酸酯基热塑性聚氨酯(PU)纺丝溶液,通过静电纺丝法制备PU纳米纤维。重点研究了纺丝溶液浓度、混合溶剂中DMF和THF的体积比、纺丝电压和纺丝溶液流速对PU纳米纤维形态、直径及其分散性的影响。结果发现,纺丝液浓度为12%,混合溶剂中DMF与THF体积比为1∶1,纺丝电压为10 kV,纺丝溶液流速为0. 8 m L/h时,通过静电纺丝法制得的PU纳米纤维粗细均匀,表面光滑,纤维之间无粘连现象,形成的纳米纤维膜空隙率高。     

静电纺丝工艺参数对PMMA／富勒烯纤维形貌的影响

采用甲苯与二甲基甲酰胺（DMF）混合溶液做溶剂,以静电纺丝法制备了含有富勒烯（C60）的聚甲基丙烯酸甲酯（PMMA）纤维,利用扫描电镜观察了纤维的形貌,分析了PMMA的质量分数、溶剂比、纺丝电压、收集距离等对纤维形貌及平均直径的影响。结果表明：PMMA溶液的浓度以及溶剂比对纤维的形貌起着主导作用,当二者变化时,纤维结构变化较大。纤维的平均直径随着PMMA浓废、纺丝电压的增大而增大;当甲苯/DMF体积比增大时,纤维平均直径先增大后减小;纤维形貌受收集距离的影响较小。     

溶液参数对静电纺丝PAN@PS复合纳米纤维形貌及结构的影响

采用同轴静电纺丝技术,以聚丙烯腈(PAN)溶液为核层、聚苯乙烯(PS)溶液为壳层,制备了PAN@PS复合纳米纤维。研究了纺丝液浓度、溶剂种类对PAN@PS复合纳米纤维形貌和结构的影响。结果表明:PS/四氢呋喃(THF)作为壳层溶液的复合纳米纤维(PAN@PS/THF)可获得相界面清晰的同轴纤维。随PS纺丝液浓度的增加,纤维的直径先增大后有所减小,整体呈现递增的趋势,当PS/THF质量分数为20%时,纤维直径约为693 nm且表面光滑。而以质量分数为20%的PS/二甲基甲酰胺(DMF)为壳层溶液的复合纳米纤维(PAN@PS/DMF)直径有所增加且纤维表面凹凸不平,呈现双相连续的结构。因此,在静电纺丝过程中,可以通过改变纺丝液的参数来调节纤维的形貌和结构。     

静电纺聚氨酯纳米纤维膜的制备及其性能研究

静电纺丝技术是制备纳米纤维膜的一种比较简单而且常用的技术。对静电纺丝技术制备聚氨酯(TPU)纳米纤维膜的最佳纺丝条件进行探索。此外,对制备的TPU纳米纤维膜进行了力学性能和介电性能的表征。结果表明,在纺丝液质量分数为12%、电压20 V、接收距离15 cm、THF与DMF的体积比为5∶1的条件下,制备的TPU纳米纤维膜表面无珠粒、纤维直径均匀,纺丝效果最佳。与纯TPU薄膜进行性能对比,TPU纳米纤维膜的断裂伸长率和拉伸强度远低于纯TPU薄膜,前者的介电常数比后者略低,但是前者的弹性模量低于后者。制备的TPU纳米纤维膜可以应用于气体过滤领域。     

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。     

不同溶剂对静电纺聚乳酸纳米纤维形态结构的影响

以聚乳酸（PLA）为原料,分别用三种不同的溶剂制得三种纺丝液并采用静电纺丝法,制备了聚乳酸纳米纤维。探讨了溶剂、电压、溶液质量分数对纤维形貌和直径的影响。结果表明,溶剂是决定PLA超细纤维形成的关键因素,三氯甲烷（CHC l3）与二甲基甲酰胺（DMF）混合溶剂（体积比为9∶1）是PLA静电纺丝较为理想的溶剂。在PLA质量分数为6%、极距15 cm、电压25 kV,流量2.5 mL/h的工艺条件下,可制备直径为1 200 nm左右的PLA纤维。     

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。     

磁场辅助静电纺PAN纳米纤维有序度的研究

采用磁场辅助静电纺丝法制备了有序聚丙烯腈(PAN)纳米纤维,分析了PAN/二甲基甲酰胺(DMF)溶液浓度、纺丝电压、注射速度、磁铁间距和溶剂DMF及DMF与二甲基亚砜(DMSO)混合溶剂等因素对PAN纤维有序度的影响。结果表明:随着PAN/DMF溶液中PAN浓度增大,PAN纤维有序度逐渐增大;注射速度对纤维有序度影响不明显;随着纺丝电压和磁铁间距增大,PAN纤维有序度先增大后减小;DMSO的加入,使溶液可纺性降低,不利于纤维有序排列;对于PAN/DMF溶液体系,适宜的磁场辅助静电纺丝的工艺参数为PAN质量分数12%,纺丝距离12 cm,电压14 k V,注射速度0.5 m L/h,磁铁间距2.5 cm,纺丝得到的PAN纳米纤维的有序度为92%。     

PVP,PEOX和PVAL纤维的电纺制备和表征

采用溶液静电纺丝法制备了聚乙烯吡咯烷酮(PVP)、聚氧化乙烯(PEOX)和聚乙烯醇(PVAL)纤维,研究了溶液浓度、外加电压和接收距离等参数对纤维形貌和直径的影响。结果表明,在选定的参数范围内,三种聚合物纤维的平均直径随溶液浓度的增大而增大,当PVP/乙醇溶液浓度为40%,PEOX溶液浓度为6%和8%,PVAL溶液浓度为8%和10%时,制得的三种纤维具有较好的形貌且其平均直径均小于1 μm。外加电压不高于30 kV时,PVP纤维的平均直径随外加电压的增大而增大,PEOX和PVAL纤维的平均直径随外加电压的增加先增大后减小。随着接收距离的增大,PVP纤维的平均直径先减小后增大,PEOX和PVAL纤维的平均直径先增大后减小。三种纤维所需的工艺参数水平不相同,其中,PVP纺丝所需溶液浓度高于PEOX和PVAL,PEOX纺丝所需外加电压和接收距离高于PVP和PVAL。     

Electrospinning of polycarbonate urethane biomaterials

Polycarbonate urethane (PCU) nano-fibers were fabricated via electrospinning using N,N- dimethylformamide (DMF) and tetrahydrofuran (THF) as the mixed solvent. The effect of volume ratios of DMF and THF in the mixed solvent on the fiber structures was investigated. The results show that nano-fibers with a narrow diameter distribution and a few defects were obtained when mixed solvent with the appropriate volume ratio of DMF and THF as 1∶1. When the proportion of DMF was more than 75% in the mixed solvent, it was easy to form many beaded fibers. The applied voltage in the electrospinning process has a significant influence on the morphology of fibers. When the electric voltage was set between 22 and 32 kV, the average diameters of the fibers were found between 420 and 570 nm. Scanning electron microscopy (SEM) images showed that fiber diameter and structural morphology of the electrospun PCU membranes are a function of the polymer solution concentration. When the concentration of PCU solution was 6.0 wt-%, a beaded-fiber microstructure was obtained. With increasing the concentration of PCU solutions above 6.0 wt-%, beaded fiber decreased and finally disappeared. However, when the PCU concentration was over 14.0 wt-%, the average diameter of fibers became large, closed to 2 μm, because of the high solution viscosity. The average diameter of nanofibers increased linearly with increasing the volume flow rate of the PCU solution (10.0 wt-%) when the applied voltage was 24 kV. The results show that the morphology of PCU fibers could be controlled by electrospinning parameters, such as solution concentration, electric voltage and flow rate.     

Electrospun nanofibers of block copolymer of trimethylene carbonate and ϵ‐caprolactone

The electrospinning behavior of a block copolymer of trimethylene carbonate (TMC) and ε‐caprolactone dissolved in N,N‐dimethylformamide (DMF) and methylene chloride (MC) was studied. The effects of the blended solvent volume ratio, concentration, voltage, and tip–collector distance (TCD) on the morphology of the electrospun fibers were investigated by scanning electron microscopy. The results indicated that the diameter of the electrospun fibers decreased with a decreasing molar ratio of MC to DMF, but beads formed gradually. With a decreasing concentration of the solution, the fiber diameter decreased; at the same time, beads also appeared and changed from spindlelike to spherical. A higher voltage and larger TCD favored the formation of smaller diameter electrospun fibers. The results of differential scanning calorimetry and X‐ray diffraction showed that the crystallinity and melting point of the electrospun fibers decreased when increasing the TMC content in the copolymer. Compared with the corresponding films, the crystallinity and melting point of the electrospun fibers were obviously increased. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1462–1470, 2006     

The change of bead morphology formed on electrospun polystyrene fibers

Polystyrene (PS) dissolved in the mixture of tetrahydrofuran (THF) and N,N-dimethyl formamide (DMF) was electrospun to prepare fibers of sub-micron in diameters. Electropinning parameters such as polymer concentration, applied voltage and tip-to-collector distance were controlled. From these parameters it was determined that while the surface tension of polymer solution had linear correlation with the critical voltage, throughput was dependent on electric conductivity. The electrospun PS fibers produced contained irregular beads and electrospinning certainly was enhanced with increasing DMF content. The bead concentration was also controlled by DMF content. The aspect ratio of the formed beads and the diameter of fibers were increased with increasing solution concentration. When PS was dissolved in only THF, an unexpected half hollow spheres (HHS) structure appeared. Also, different shape forms of PS non-woven mats have been prepared by controlling electrospinning parameters.     

Effects of processing parameters on morphology of electrospun polystyrene nanofibers

This study focused on the preparation of electrospun polystyrene (PS) nanofibers. PS solutions were prepared in single (dimethylformamide; DMF, dimethylacetamide; DMAc or tetrahydrofuran; THF) and mixed solvent (DMF/THF and DMAc/THF) systems with and without tetrabutylammonium bromide (TBAB) salt. The effects of PS concentration, solvent system, the addition of salt, appearance and diameter of PS fibers were examined. The average diameter of the as-spun fibers increased upon increasing PS concentration. The morphology of the fibers significantly depended on the properties of the solvents. The obtained fibers were smooth without any beads and their diameters were affected by the amount of THF in the solvent and PS concentration. The beads in the fibers disappeared and the fiber diameter significantly decreased after the addition of TBAB. The smallest diameter and the narrowest diameter distribution of PS nanofibers (376±36 nm) were obtained from 15% PS solution in DMAc with 0.025% w/v TBAB.     

The morphology,mechanical properties,and flammability of aligned electrospun polycarbonate (PC) nanofibers

The electrospinning of the polycarbonate (PC) solutions was performed for the variable electrospinning parameters such as polymer concentration, solvent composition, applied voltage, flow rate, and take‐up velocity in order to evaluate changes of morphology, mechanical properties, and flammability of the aligned PC nanofibers as a function of the electrospinning parameters. It was found that the ratio of THF/DMF solvent in the electrospinning parameters had a major effect on the spinnability and fiber morphology. Furthermore, it was confirmed that the mechanical properties were dependent upon the fiber morphology. The spinnability of the PC solutions with a lower THF ratio in THF/DMF solvent was poor. The aligned electrospun PC fiber with the best morphology was made in the range of polymer concentration of 22%, solvent ratio of 50:50 THF : DMF, applied voltage of 14 kV, flow rate of 0.050 ml/m, and a take‐up velocity of 7.3 m/s. The ultimate strength and initial modulus of the 80% drawn 22% PC fiber were 64 ± 2 MPa (commercial 55–75 MPa) and 1.9 ± 0.1 GPa. The heat release capacity (HRC) of the 22 and 25% PC fiber were 275 ± 27 J/g K and 198 ± 1 J/g K. It was found that the flame resistance of the electrospun PC nanofiber was superior to that of the PC raw material (HRC ～360 J/g K). POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

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。     

Filtration properties of electrospun ultrafine fiber webs

Electrospun fiber webs were prepared at various spinning conditions. The effect of electrospinning parameters on fiber morphology and filtration performance of electrospun webs was investigated. The processing variables considered were only the applied voltage and rotation speed of a drum type collector. The fiber diameter and mean pore size of the electrospun webs decreased with increasing applied voltage and collector speed. Pressure drop and aerosol collection efficiency of the electrospun fiber webs were increased with decreasing fiber and pore size. Additionally, it was found that the filtration performance of the electrospun web was much greater than that of a commercial high efficiency air filter media made of glass fibers.