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1.
Ultra fine fibers were electrospun from regenerated silk fibroin/formic acid solution. Effect of some process parameters on the morphology, diameter and variation in fiber diameter of electrospun fibers were experimentally investigated. Scanning electron microscope was used for the measurement of fiber diameter. Fibers with diameter ranging from 80 to 210 nm were collected depending on the solution concentration and the applied voltages. Response surface methodology (RSM) was used to obtain a quantitative relationship between selected electrospinning parameters and the average fiber diameters and its distribution. It was shown that concentration of silk fibroin solution had a significant effect on the fiber diameter and the standard deviation of the fiber diameter. Applied voltage had no significant effect on the fiber diameter and its standard deviation.  相似文献   

2.
Meta-aramid fibers were dissolved in four different solvent systems (DMAc, DMF, NMP, and DMSO) and two kinds of salts (LiCl and CaCl2) were also introduced in this paper. Meta-aramid fibers had a limited solubility in above four solvents, however, fast dissolution could be obtained after adding a certain amount of salt (LiCl or CaCl2). The concentration of salts was found to be an important role in affecting meltaging, dissolving time and viscosity of electrospun solution. Electrospun meta-aramid nanofibers mats were successfully prepared. A series of characterizations had been carried out by using SEM. The results shows the diameter of meta-aramid nanofibers ranging from 100 to 500 nm. The average diameter of the nanofibers increased with the concentration of meta-aramid fiber solution and the salt solution. A preferable morphology of meta-aramid nanofibers could be obtained under LiCl/DMAc system. While the electrospun nanofibers made in CaCl2/DMAc solvent system had a better performance in thermal stability than that prepared in LiCl/DMAc system. Among the four kinds of prepared nanofibers, the nanofibersmat electrospun in LiCl/DMAc system with a concentration of meta-aramid solution at 11 wt% exhibit the best mechanical properties.  相似文献   

3.
Biodegradable edible sub-micron electrospun zein fibers were prepared using acetic acid as solvent. The solution concentration at three levels: 22, 26 and 30 w/v %, the electrospinning voltage at three levels: 10, 20 and 30 kV, the solution flow rate at three levels: 4, 8 and 12 ml/h and the distance between needle tip and collector at three levels: 10, 15 and 20 cm were studied. Central composite design (CCD) was utilized to modeling the effect of electrospinning parameters of zein solution on average fiber diameters and the data were analyzed using response surface methodology (RSM). Coefficient of determination, R2, of fitted regression model was higher than 0.9 for response. The analysis of variance table showed that the lack of fit was not significant for response surface model at 95 %. Therefore, the model for response variable was highly adequate. Results also indicated that the solution concentration had significant influence (P<0.0001) on morphology and diameter of fibers. By increasing the solution concentration, uniform and bead-free fibers were obtained. As the solution concentration was increased, the average fiber diameters were also increased. Furthermore, the electrospinning voltage had significant effect (P<0.0001) on average fiber diameters. By increasing the electrospinning voltage, the average fiber diameters increased. The solution flow rate and the distance between needle tip and collector had no significant influence on the average fiber diameters. According to model optimization, the minimum average fiber diameter of electrospun zein fiber is given by following conditions: 24 w/v % zein concentration, 10 kV of the applied voltage, 10 cm of needle tip to collector distance, and 4 ml/h of solution flow rate.  相似文献   

4.
Electrospinning is an efficient method to produce polymer fibers with a diameter range from nanometers to a few microns using an electrically driven jet. Electrospun nanofiber nonwoven fabrics can be applied into different areas with higher air volume fraction, especially applied into textile materials with good warmth retention property. In this article, the air volume fraction in nonwoven mats made of electrospun nanofibers was verified by studying fiber volume fraction in the mats. Then the relationship between fiber volume fraction and fiber diameter was derived, and the fiber volume fraction is in direct ratio to the square of fiber radius. By experimental verification, to get electrospun PAN nanofiber nonwoven mats with high air volume fraction about 99 %, it can fix the polymer concentration on 8 %. The voltage fixed on 20 kV, the tip-to-collector distance on 15 cm. The experiment is in accordance with the theory excellently.  相似文献   

5.
In this study, electrospinning of poly(ε-caprolactone) (PCL) and its optimum preparation conditions were examined in detail using various solvent systems, such as formic acid, dichloromethane/dimethyl formamide (DMF), chloroform/DMF, and dichloroethane. The average fiber diameter of the electrospun PCL mat was controlled by the solvent used with a proper concentration of PCL dope solution. Different fiber sizes (0.1, 0.8, 1.9, and 3.4 μm) of uniform PCL mats were fabricated and the effects of fiber size on surface morphology, tensile properties and cell behavior were investigated. Here, we manipulated much broader range of average fiber diameter of the mats, from nano to several micron size of fiber. It was found that the fiber diameter greatly affected topology (surface roughness) and mechanical properties of the electrospun PCL mat and consequently, they influenced the cell behavior (adhesion and proliferation) significantly. We expect that these results will provide more feasible application of electrospun PCL scaffold in tissue engineering through the co-relations in structure and property of PCL fiber mat on cell behavior.  相似文献   

6.
Wire electrodes for needleless electrospinning consist of stainless steel wires in place of cylinder electrodes. The effects of different numbers of constituent stainless steel wires on the morphology and diameter of polyvinyl alcohol (PVA) fibers are examined. With 1, 2, 3, or 4 stainless steel wires being twisted as wire electrodes, an 8, 10, or 12 wt.% polyvinyl alcohol (PVA) solution is electrospun into PVA nanofibers by using a needleless electrospinning machine. The morphology and diameter of PVA nanofibers is observed by scanning electron microscopy. The combination of the number of stainless steel wires (two), PVA solution (10 wt.%), and the collecting distance (10 cm) results in the finest diameter and an evenly formed fiber morphology. In addition, the nanofibers exhibit a wide range of diameters when electrospun with an electrode consisting of more than two stainless steel wires. Compared with the cylinder electrode, the use of a wire electrode can form nanofibers, which results in a more even morphology.  相似文献   

7.
Electrospun atactic polypropylene (PP) fibers are thicker than those obtained from isotactic PP, although the viscosity of molten PPs is almost same. Thus we focused on the effect of tacticity of PP on fiber diameters. The PP samples with various tacticity were prepared by changing the blend ratio of isotactic PP and atactic PP. Melt-electrospinning is performed by using blended samples, and then electrospun fibers were observed by scanning electron microscope to evaluate fiber diameter of obtained fibers. It is clear that the diameter of electrospun PP fibers decreases as high tacticity content of PP increases. This result suggests that tacticity of samples is an important factor to control the electrospun fiber diameter.  相似文献   

8.
Polymer electrospun fibers are potential candidates for use as ionic dye adsorbents, due to its low cost and massive production provided by a simple nanofabrication method. The optimization in the processing variables for development of more efficient adsorbents revealed a strong dependence between the fiber diameter and the adsorption capacity of fibers, which was measured as a function of dye concentration, pH, adsorbent amount and contact time. The available active sites on electrospun fibers favor the efficient dye removal and easy desorption, allowing the successive reuse of electrospun fibers, preserving typical adsorption capacity of 135.37 mg·g-1 in association with fast desorption at acidic condition, allowing successive reuses of adsorbents.  相似文献   

9.
Flexible tubular structures fabricated from solution electrospun fibers are finding increasing use in tissue engineering applications. However it is difficult to control the deposition of fibers due to the chaotic nature of the solution electrospinning jet. By using non-conductive polymer melts instead of polymer solutions the path and collection of the fiber becomes predictable. In this work we demonstrate the melt electrospinning of polycaprolactone in a direct writing mode onto a rotating cylinder. This allows the design and fabrication of tubes using 20 μm diameter fibers with controllable micropatterns and mechanical properties. A key design parameter is the fiber winding angle, where it allows control over scaffold pore morphology (e.g. size, shape, number and porosity). Furthermore, the establishment of a finite element model as a predictive design tool is validated against mechanical testing results of melt electrospun tubes to show that a lesser winding angle provides improved mechanical response to uniaxial tension and compression. In addition, we show that melt electrospun tubes support the growth of three different cell types in vitro and are therefore promising scaffolds for tissue engineering applications.  相似文献   

10.
A series of PU fibrous membranes were fabricated by using electrospinning method. The microstructure of the membranes was characterized by field-emission scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectrum. Their mechanical properties were tested by dynamic mechanical thermal analysis and stress-strain behaviors. The solution concentration, the applied voltage and the tip-collector distance had an effect on the crystallinity degree and molecular orientation of PU, the size and distribution of the fiber diameter and the point-bonded structures between the fibers, leading to the change in the microstructure and the mechanical properties of the fibrous membrane. Fibers with a smaller diameter had higher strength but lower ductility. The fibrous membranes indicated the similar stress-strain behaviors, which slopes in the initial stage were low and that in the later stage were high. The initial elastic behavior with the low Young’s modulus were attributed to the network structure of the fibrous membranes and that with the high Young’s modulus was from the electrospun PU fibers.  相似文献   

11.
Silk fibroin (SF) nanofibers were prepared by electrospinning and their application as an enzyme immobilization support was attempted. By varying the concentration of SF dope solution the diameter of SF nanofiber was controlled. The SF nanofiber web had high capacity of enzyme loading, which reached to 5.6 wt%. The activity of immobilizedα-chymotrypsin (CT) on SF nanofiber was 8 times higher than that on silk fiber and it increased as the fiber diameter decreased. Sample SF8 (ca. 205 nm fiber diameter) has excellent stability at 25°C by retaining more than 90 % of initial activity after 24 hours, while sample SF11 (ca. 320 nm fiber diameter) shows higher stability in ethanol, retaining more than 45% of initial activity. The formation of multipoint attachment between enzyme and support might increase the stability of enzyme. From these results, it is expected that the electrospun SF nanofibers can be used as an excellent support for enzyme immobilization.  相似文献   

12.
A novel enclosed air-jet electrospun set-up was described for fabricating nanofibers with high production rate. This study showed the components of the spinneret device, mainly including a spray nozzle, a liquid storage chamber, a connector and a gas storage chamber. By using this device, the polyacrylonitrile (PAN) nanofiber mats were fabricated with increased production rate of nearly more than ten times as compared with using single-needle electrospun set-up. The jets path, fibers morphology, mats throughput, along with forces acted on the bubbles in four positive electrodes were investigated in this report. The electric fields and equipotent lines distribution with corresponding positive electrodes were simulated with a second-dimension FEA (An-soft Maxwell) for analyzing experiment results. The simulated results showed that the strength of electric fields was related to the size of the charged area, and the uniform of electric fields depended on the mutual effects of electric fields from different charged position. The average diameter of fibers was the thinnest with about 280 nm and the standard deviation of fibers was 34.95 % with the top surface of the solution storage chamber and the nozzle charged. When the whole nozzle was charged, the diameter of fibers increased to 323.27 nm but the standard deviation reduced to 29.53 %. Especially, with the top surface of the solution storage chamber charged, the fibers showed thinner mean diameter of 290 nm and the most uniform standard deviation of 28.02 %. With further reduction of the charged area, a few beads-like fibers with the thickest diameter and the worst standard deviation were appeared.  相似文献   

13.
Electrically conducting nanofibers based on cellulosic materials offer cheap and safe class of materials that can be used for water desalination. In the present work, high conducting cellulose triacetate (CTA) nanofibers containing multiwall carbon nanotubes (MWCNTs) with very low percolation threshold concentration (0.014 wt%) were produced by electrospinning. Unprecedentedly, a hydrophilic ionic liquid consists of 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) was used to dissolve CTA producing a solution of 10 wt%. This CTA solution was used to engineer both bare CTA nanofibers and CTA nanofibers impregnated with MWCNT. The fabricated nanofibers were characterized by the field emission-scanning electron microscopy (FE-SEM) and the high-resolution transmission electron microscopy (HR-TEM). Both FE-SEM and HR-TEM images showed that the MWCNTs were inserted and uniformly distributed inside electrospun nanofibers. Furthermore, mechanical properties such as tensile strength of MWCNTs loaded-CTA electrospun nanofibers was significantly improved by up to 280 % and 270 % for the Young modulus, when compared with the bare CTA fibers. In addition, the surface properties as the hydrophilicity of electrospun nanofibers membrane was enhanced due to the presence of MWCNTs. Moreover, the electrical conductivity of MWCNT loaded-CTA electrospun nanofibers was greatly enhanced after the implementation of the MWCNTs inside the CTA fiber. The performance of composite nanofiber for water desalination was examined in a lab-scale classic capacitive deionization (CDI) unit, at different concentrations of salt. The obtained data revealed that the electro-adsorption of anions and cations on the surface of MWCNTs loaded-CTA electrospun nanofibers electrodes were monitored with time and their concentration were decreased progressively with time and reaches equilibrium.  相似文献   

14.
In this study, we evaluated the effect of the molecular weight of the polymer on electrospun poly(ethylene terephthalate) (PET) nonwovens, and their mechanical properties as a function of the linear velocity of drum surface. Polymer solutions and electrospun PET nonwovens were characterized by means of viscometer, tensiometer, scanning electron microscope (SEM), wide angle X-ray diffraction measurement (WAXD) and universal testing machine (UTM). By keeping the uniform solution viscosity, regardless of molecular weight differences, electrospun PET nonwovens with similar average diameter could be obtained. In addition, the mechanical properties of the electrospun PET nonwovens were strongly dependent on the linear velocity of drum surface. From the results of the WAXD scan, it was found that the polymer took on a particular molecular orientation when the linear velocity of drum surface was increased. The peaks became more definite and apparent, evolving from an amorphous pattern at 0 m/min to peaks and signifying the presence of crystallinity at 45 m/min.  相似文献   

15.
After the addition of a surface-active agent, sodium dodecyl benzene sulfonate (SDBS), electrospun polyvinyl alcohol (PVA) nanofibres showed a significant enhancement in the mechanical properties, such as improved tensile strength and elongation at break. The improved crystallinity and strong intermolecular hydrogen bonds between the molecules of SDBS and PVA were the two main factors that improved the mechanical properties. In addition, a sharp decrease in surface tension of PVA solution with the addition of SDBS was observed, and the protruding droplet at the tip of needle diminished in the electrospinning process.  相似文献   

16.
Synthesis of biocompatible polymer nanofibers is valuable, due to their use as a cover for burns and as a replacement for bandage because of their antimicrobial properties. In this study, electrospinning of chitosan(Ch) and nanofibers synthesis with antibacterial properties was investigated. Nanofibers with antibacterial properties were synthesized by electrospun of Ch/poly(L-lactide)(PLA)/Imipenem(Imi) polymer solution. The results showed that the optimized ratio of Ch/PLA polymer solution was ratio of 50:50 and Ch 2 wt% and PLA 10 wt% polymer solution was the best weight percentage for nanofiber preparation. Also, the average diameter of Ch/PLA/Imi nanofibers was 143 nm and measured with ImageJ software. Afterwards, the antibacterial properties of Imi as additives (with different percentages) was studied in the polymer solution. The scanning electron microscopy (SEM) images and antibacterial tests were showed that the electrospun of Ch/PLA/Imi polymeric nanofibers were effective against Gram negative bacteria Escherichia coli (E. coli) and inhibited growth of E. coli. The growth and viability percentage of fibroblast cells with nanofibers in αMEM culture are at desirable levels after 6 days.  相似文献   

17.
In this study, the morphology and crystal polymorphism of electrospun blend nanocomposite of graphene filled-polyvinylidene fluoride (PVDF)/poly(methyl methacrylate) (PMMA) nanofibers were investigated. The preparation of the nanofibers was carried out by synthesis of PMMA/graphene as a masterbatch through in-situ polymerization, and then followed by compounding with PVDF solution in the different ratios. The process of electrospinning was done at three selective conditions of temperature, moist and ordinary environment. Crystallinity, morphology and thermal properties of nanofibers were characterized by X-ray diffraction spectroscopy (XRD), differential scanning calorimetric (DSC), Transmittance Electron Microscopy (TEM), Thermogravimetric Analyses (TGA), and Field Emission Scanning Electron Microscopic (FE-SEM). The enhancement of β crystal formation in the electrospun graphene-filled blend nanofibers was confirmed by XRD and DSC results. This can be ascribed by the benefits of solution casting, mechanical stretching, high electric field, PMMA interactions and graphene restrictions, altogether in one simple process. Also, presence of water molecules during the electrospinning causes the orientation of fluorine atoms in PVDF due to polar-polar interactions which enhance the polar conformation even in the pure PVDF nanofibers.  相似文献   

18.
The electrospinnability of aloe vera gel and the release mechanism as well as the kinetic of its release from poly vinyl alcohol (PVA) nanofibrous matrix is reported. Addition of PVA by an amount of only 1 % (w/w) to aloe vera solution made its electrospinning possible leading, to the fabrication of aloe vera nanofiber (99 %) with an average diameter of around 80 nm. Electrospinning of aloe vera-PVA solutions (25-75, 50-50, 75-25) led to the fabrication of nanofibers with average diameter of around 55, 105 and 110 nm, respectively. FTIR analysis showed no reaction between aloe vera and PVA. X-ray diffraction patterns showed no considerable effect from aloe vera on the amorphous structure of PVA. The release mechanism of aloe vera from PVA matrix in phosphate buffer solution was of Ficki type and the kinetic of the release followed Higuchi model. Aloe vera or aloe vera-PVA electrospun nanofibers may be used as an aloe vera release system in wound care. In a phosphate buffer solution, at least 60 percent of aloe vera is released in the first hour and about 90 % of aloe vera is released in 2-4 hours depending on the diameter of the nanofibers.  相似文献   

19.
Semicrystalline poly(ethylene terephthalate) (cPET)/amorphous poly(ethylene terephthalate) with isophthalic acid (aPET) blends with 100/0, 75/25, 50/50, 25/75, and 0/100 by weight ratios were dissolved in a mixture of trifluoroacetic acid (TFA)/methylene chloride (MC) (50/50, v/v) and electrospun via the electrospinning technique. Solution properties such as solution viscosity, surface tension and electric conductivity were determined. The solution viscosity slightly decreased as aPET content increased, while there was no difference in surface tension with respect to aPET composition. The characteristics of the electrospun cPET/aPET blend nonwovens were investigated in terms of their morphology, pore size and gas permeability. All these measurements were carried out before and after heat treatment for various blend weight ratios. The average diameter of the fibers decreased with increasing aPET composition due to the decrease in viscosity. Also, the morphology of the electrospun cPET/aPET blend nonwovens was changed by heat treatment. The pore size and pore size distribution varied greatly from a few nanometers to a few microns. The gas permeability after heat treatment was lower than that before heat treatment because of the change of the morphology.  相似文献   

20.
Silver nanoparticles imbedded in polyacrylonitrile (PAN) nanofibers and converted into carbon nanofibers by calcination was obtained in a simple three-step process. The first step involves conversion of silver ions to metallic silver nanoparticles, through reduction of silver nitrate with dilute solution of PAN. The second step involves electrospinning of viscous PAN solution containing silver nanoparticles, thus obtaining PAN nanofibers containing silver nanoparticles. The third step was converting PAN/Ag composites into carbon nanofibers containing silver nanoparticles. Scanning electron microscopy (SEM) revealed that the diameter of the nanofibers ranged between 200 and 800 nm. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) showed silver nanoparticles dispersed on the surface of the carbon nanofibers. The obtained fiber was fully characterized by measuring and comparing the FTIR spectra and thermogravimetric analysis (TGA) diagrams of PAN nanofiber with and without imbedded silver nanoparticles, in order to show the effect of silver nanoparticles on the electrospun fiber properties. The obtained carbon/Ag composites were tested as gram-class-independent antibacterial agent. The electrosorption of different salt solutions with the fabricated carbon/Ag composite film electrodes was studied.  相似文献   

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