Method For Production Of Nanofibers Research Articles

Production of gelatin fibrous mats using different nanofiber production methods for medical applications and comparison of their properties.

In the literature, there are studies on medical applications using different nanofiber production methods with natural polymers. However, each system has different fiber-forming capabilities. For this reason, in this study, we investigated the production of nanofibers from a biodegradable natural polymer, gelatin, using four separate nanofiber production methods, namely electrospinning (ES), electroblowing (EB), solution blowing (SB), and centrifugal spinning (CS). Our aim was to determine the most suitable fibrous web structure for medical applications and contribute to science in this respect. It was observed that the thinnest fibers (386 nm) and the heaviest mats (15.975 g m-2) were produced by the SB method as a result of using 10 wt.% gelatin solution with a total of 10 mL. With the ES and EB methods, tighter fabric structures were obtained than with the others due to the presence of electric fields. In the CS method, more and bead-free fibers were produced due to the increase in viscosity with a 12.5 wt.% gelatin solution. Moreover, with the concentration of 12.5 wt.%, the fiber diameters of SB and CS samples increased about 2-fold.

AN OVERVIEW ON RECENT ADVANCEMENT METHODS AND CHARACTERIZATION OF NANOFIBER TECHNOLOGY

This paper highlights the unique features and a brief introduction to the Nanofiber production methods, characterization and their potential applications. Nanofibers are made from various materials and have been used for a wide range of applications such as reinforcement fibers in composites, protective clothing, filtration, biomedical devices, electrical and optical applications, and nanosensors. Nanofibers with controlled diameters range from Nanometer to Micrometer which possess unique properties like a high surface area- to-volume ratio, low density and high pore volume. These properties make nanofibers more advantageous. The most widely used techniques are electro spinning and electro spunning methods. The potential uses for the different nanofiber technology was identified and many of the techniques are still in the developmental stage, but some of them are already fulfilling fledgy roles in the fields of biomedical and industry. Other issues encounters in the technology limitations, research challenges, and future trends are also discussed in the article.

Optimization of electric field uniformity of multi-needle electrospinning nozzle

Multi-needle electrospinning technology is a method for mass production of nanofibers, which can improve the production efficiency of nanofibers by increasing the number and density of needles for multi-needle electrospinning. However, when the arrangement density of the needle is high, the electric field of the needle tip is not uniform, causing instability such as jet dripping and broken jet. In this paper, the electric field uniformity optimization problem of multi-needle electrospinning technology is used to simulate the needle tip electric field by using COMSOL finite element analysis software. The influence of the needle size and the dielectric material on the electric field of the tip was studied. Finally, the method of using dielectric material on the tip of the middle part of the needle is beneficial to the electric field uniformity. The uniformity of the needle tip electric field in the case of high-density arrangement of the needle is realized, and the nozzle is provided for mass production of nanofibers by multi-needle electrospinning.

Production and characterization of chitosan-gelatin nanofibers by nozzle-less electrospinning and their application to enhance edible film’s properties

Abstract In this study nozzle-less electrospinning device has been introduced as a promising technology to produce food grade nanofibers with high production yield in comparison to nozzle based instrument. Electrospinning was set up with pure gelatin solutions and different volume ratios of chitosan to gelatin. SEM images showed that by increasing volume ratio of chitosan to gelatin a decrease in fiber diameter could be observed. The thinnest nanofibers had mean diameter of 96.26 ± 34.44 nm. DSC analysis indicated that thermal resistance of the nanofiber was higher than pure ingredients. ATR-FTIR analysis showed that the main peaks of ingredients can be detected in spectrum of produced nanofibers. The optimum nanofibers were used to enhance physical properties of edible gluten film. Nanofiber treated edible film had lower water vapor permeability and better mechanical properties in comparison to blank sample. The maximum force of the edible film containing 2 mg/cm2 nanofibers that could tolerate was 3.12 N and for blank edible film without nanofibers was 0.58 N. The results of this study indicated that nozzle-less electrospinning can be applied as a new method for production of nanofibers in large scale which can be further applied for enhancement of mechanical properties of edible films.

Development of Carbon Nanofiber Yarns by Electrospinning

In recent years the commercial importance of carbon nanofiber has increased due to its high mechanical properties, electrical and thermal conductivity and lightness. Therefore, carbon nanofibers are candidate to replace many commercial products. In general carbon nanofibers are produced from precursor fiber. Polyacrylonitrile (PAN) is usually used as precursor fiber because of comparatively high carbon yield and a thermally stable and highly oriented molecular structure. Large number of scientific publications have been demonstrated with the help of progress in nanofiber production methods, such electrospinning, centrifugal- spinning, air blowing from melt or solution, and optimization of process parameters of those methods. In this study, PAN nanoyarn is first obtained by the electrospnning method which is very convenient process for producing thin fiber. Stabilization is then applied by exposure to air at 230°C to provide thermally stable structure so that the resulting PAN nanofibers could be thermally durable during the carbonization process at high temperature. Finally, the process for the carbonization of the stabilized sample is operated in a argon gas atmosphere at 600°C. The produced material is characterized by SEM to observe its morphology.

Numerical and experimental study on the steady cone-jet mode of electro-centrifugal spinning

This study focuses on a numerical investigation of an initial stable jet through the air-sealed electro-centrifugal spinning process, which is known as a viable method for the mass production of nanofibers. A liquid jet undergoing electric and centrifugal forces, as well as other forces, first travels in a stable trajectory and then goes through an unstable curled path to the collector. In numerical modeling, hydrodynamic equations have been solved using the perturbation method—and the boundary integral method has been implemented to efficiently solve the electric potential equation. Hydrodynamic equations have been coupled with the electric field using stress boundary conditions at the fluid-fluid interface. Perturbation equations were discretized by a second order finite difference method, and the Newton method was implemented to solve the discretized non-linear system. Also, the boundary element method was utilized to solve electrostatic equations. In the theoretical study, the fluid was described as a leaky dielectric with charges only on the surface of the jet traveling in dielectric air. The effect of the electric field induced around the nozzle tip on the jet instability and trajectory deviation was also experimentally studied through plate-plate geometry as well as point-plate geometry. It was numerically found that the centrifugal force prevails on electric force by increasing the rotational speed. Therefore, the alteration of the applied voltage does not significantly affect the jet thinning profile or the jet trajectory.

Production of Synthetic, Para-Aramid and Biopolymer Nanofibers by Immersion Rotary Jet-Spinning

Nanofiber production platforms commonly rely on volatile carrier solvents or high voltages. Production of nanofibers comprised of charged polymers or polymers requiring nonvolatile solvents thus typically requires customization of spinning setup and polymer dope. In severe cases, these challenges can hinder fiber formation entirely. Here, a versatile system is presented which addresses these challenges by employing centrifugal force to extrude polymer dope jet through an air gap, into a flowing precipitation bath. This voltage-free approach ensures that nanofiber solidification occurs in liquid, minimizing surface tension instability that results in jet breakup and fiber defects. In addition, nanofibers of controlled size and morphology can be fabricated by tuning spinning parameters including air gap length, spinning speed, polymer concentration, and bath composition. To demonstrate the versatility of our platform, para-aramid (e.g., Kevlar) and biopolymer (e.g., DNA, alginate) nanofibers are produced that cannot be readily produced using standard nanofiber production methods.

Single Wall Carbon Nanotube-Containing PVA Based Carbon Nanofibers for Lithium Ion Battery Anodes

Lithium ion batteries have increasing importance due to the urgent demand for widespread applications in electric/hybrid vehicles, electronic devices, and the grid energy storage. Graphite is one of the most commonly used anode material with low theoretical capacity(372mAh/g) and limited rate capability. In order to improve battery Li-ion storage capacity many researchers have investigated different carbonaceous anode materials with various configurations. Among them, carbon nanofiber is of particular interest for providing high capacity and cycling stability due to its high surface area, porous structure and high electric conductivity which not only shorten the lithium ion path through the electrode but also provide large electrode/electrolyte interface for the charge-transfer reaction properties. Carbon nanofibers can be directly used as free standing and binder free anodes. There are several nanofiber production methods, among which electrospinning is the most promising due to its simplicity and versatility. Carbon nanofibers can be produced with different precursors such as Pitch, polyacrylonitrile(PAN), polyvinypyrrolidone(PVP), polyvinyl alcohol(PVA) etc. Polyvinyl alcohol is a promising material due to its water soluble and environmentally friendly character. In this study we report a method to produce free-standing binder free single wall carbon nanotube containing carbon nanofibers as anode for lithium ion battery. Composite nanofibers prepared via electrospinning of single wall carbon nanotubes (SWCNT) dispersed into polyvinyl alcohol solution, followed by iodination at 100°C and heat treatment in an inert atmosphere at 800°C. Carbon nanotubes were added to the polymer solution in different concentrations 0,1% , 1%, and 5 %. An increase of the carbon nanotube concentration in the fibers led to carbonized nanofiber mats with increased electrical conductivity. TGA and Raman analyses showed that carbon nanotubes presence improves the carbon yield of the mats and their handleability. Galvanostatic cycling tests of half cells revealed that addition of carbon nanotubes improves battery capacity. We attribute the capacity increase of the composite nanofibers to the carbon nanotubes structure. Moreover carbon nanotubes increased the handleabilitiy of the mat which is crucial for freestanding, binder free anode materials.

A Scaling Model for Predicting the Gas-Channel Formation Period in Crater-Like Electrospinning of Nanofibers

Crater-like electrospinning is a novel and cost-effective method for the mass scale production of nanofibers. The gas channel in the polymer solution plays a key role to produce a bubble Taylor cone or a crater-like Taylor cone, which is the key to eject the thin fluid jets (finally solidified into nanofibers) in electrospinning process. However, the formation mechanism of gas channel of crater-like Taylor cone is still unclear, which hinders further development of this process. In this work, a simple and effective scaling model was firstly established to predict the period of the gas-channel formation in the polymer solution during electrospinning process. Our theoretical analysis showed that the gas-channel formation period was mainly determined by the input air pressure during the process. The relationship between the formation period and the input air pressure followed a scaling law. In order to verify the model, crater-like electrospinning process was carried out and a high-speed digital camera was employed to observe the gas channel. The experimental results agree well with the scaling model, which indicates that the proposed system is feasible. The scaling model could be useful in helping us to understand the process.

Novel nanofiberous membrane fabricated via electrospinning of wastage fuzzes of mechanized carpet used for dye removal of the carpet dyeing wastewater

Novel nanofibrous membrane was fabricated by using electrospinning of wastage fuzzes of mechanized carpet which was used to remove the dye of the textile wastewater. SEM images showed that nanofibers with average diameters of 200 nm were successfully fabricated by electrospinning technique. The physicochemical properties of electrospun nanofiberous membranes were studied by differential scanning calorimetry (DSC), energy-dispersive X-ray (EDX), and Fourier transform infrared (FTIR) spectroscopy. FTIR confirmed the presence of C≡N, C˭N, and C‒N groups in the electrospun nanofibers which are the main functional groups of polyacrilonitrile (PAN). The resulting membrane showed dye retention of 96% of carpet dyeing wastewater, demonstrating the high separation potential of such membrane for wastewater treatment. We believe that simple approaches such as the present one would open up enormous possibilities in effective uses of wastage fuzzes of textile industry, considering the fact that electrospinning is a cost-effective method for the mass scale production of nanofibers.

Recent Nanofiber Technologies

This article is a perspective that includes a brief introduction to nanofiber production methods, their potential applications, and three review articles in the field of nanofibers. Although the full range of applications that best exploit these new developments are yet to be developed, the emerging innovative applications of nanofibers in biomedical, sensor, electronic, and other areas will likely be enabled or enhanced by these recent advances in several key techniques. Three review articles, distinct but interrelated, discuss technical research and development, and include possible applications for several industries in the polymer nanofiber arena.

A simple recipe for an efficient TiO2 nanofiber-based dye-sensitized solar cell

Development of highly efficient dye-sensitized solar cells (DSSCs) with good photovoltaic parameters is an active research area of current global interest. In this article, we provide a simple recipe for the fabrication of electrospun TiO(2) nanorod-based efficient dye-sensitized solar cell using a Pechini-type sol. The Pechini-type sol of TiO(2) nanofibers produces a highly porous and compact layer of TiO(2) upon doctor-blading and sintering without the need for an adhesion and scattering layers or TiCl(4) treatment. The best nanofiber DSSCs with an area of ~0.28 cm(2) shows an efficiency of ~4.2% under standard test conditions (100 mW/cm(2), 25°C and AM1.5 G) and an incident photon-to-electron conversion efficiency (IPCE) of ~50%. Impedance measurements show lower charge transfer resistance that improved the fill factor. We believe that simple approaches such as the present one to develop nanofiber DSSCs would open up enormous possibilities in effective harvesting of solar energy for commercial applications, considering the fact that electrospinning is a cost-effective method for the mass scale production of nanofibers and nanorods.