• Journal of Hydrogen and New Energy
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• v.29 no.1
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• pp.71-80
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• 2018

Electrospinning is a versatile technique that utilizes electrostatic forces to produce very thin and fine fibers of polymer ranging from submicron to nanometer scale. The technique can be applied to fibers of a various polymer types. Working parameters in the electrospinning are very important to understand not only the nature of electrospinning but also the conversion of polymer solutions into nanofibers through electrospinning. Those parameters in the electrospinning can be broadly divided into three parts. The first parameter is solution parameters such as molecular weight of polymer, concentration, viscosity, surface tension and conductivity/surface charge density of solution. The second parameter is process such as voltage, distance between the collector and the tip of the syringe, shape of collectors, flow rate. The third parameter is ambient parameters such as humidity and temperature. Fibers which made by electrospinning with working parameters are applied for various fields according to shape such as medical, cloth, photodiode, a sensor technology, catalyst, filtration, battery etc.

• Journal of Sensor Science and Technology
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• v.24 no.1
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• pp.35-40
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• 2015

Electrospinning method has easy preparation of nanofibers with a simple and versatile technique. Electrospun nanofiber is widely used by the simple approach and have great potentials in the numerous applicaitons of medicine, photonics, catalysts, sensors, etc. including advantage of their specific characteristics such as large surface to volume ratio. This paper focused on the fabrication of cobalt electrospun nanofibrer for applications such as electronic, optical and mechanical devices by metal based material. We fabricated cobalt nanofibers on aluminum foil by an electrospinning method. The electrospinning process was performed at a high voltage, 8 kV. The distance between the needle tip and the solution surface in the bath was 5 cm. The PVB - cobalt based nitrate solution was filled in a 10 mL syringe connected to a 22 gauge needle. We confirmed electrospun cobalt nanofiber after annealing process by SIMS (Secondary Ion Mass Spectrometry) analysis. The concept design, fabrication and results of mapping measurements are reported.

• Fibers and Polymers
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• v.3 no.2
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• pp.73-79
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• 2002

Nanoscaled PVA fibers were prepared by electrospinning. This paper described the electrospinning process, the processing conditions fiber morphology, and some potential applications of the PVA nato-fibers. PVA fibers with various diameters (50-250 nm) were obtained by changing solution concentration, voltage and tip to collector distance (TCD). The major factor was the concentration of PVA solution which affected the fiber diameter evidently. Increasing the concentration, the fiber diameter was increased, and the amount of beads was reduced even to 0%. The fibers were found be efficiently crosslinked by glyoxal during the curing process. Phosphoric acid was used as a catalyst activator to reduce strength losses during crosslinking. Scanning electron micrograph (SEM) and differential scanning calorimetric (DSC) techniques were employed to characterize the morphology and crosslinking of PVA fibers. It was fecund that the primary factor which affected the crosslinking density was the content of chemical crosslinking agent.

• Korean Journal of Materials Research
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• v.17 no.5
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• pp.278-282
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• 2007

Polyacrylonitrile nanofibers were fabricated by co-electrospinning technique and were characterized using scanning electron microscopy(SEM). We have evaluated systematically the effects of the important processing parameters affected on the morphology of the formed fibers; voltage, solution concentration and tip to collector distance. PAN nanofibers of about 200 nm${\sim}$2500 nm in diameter were well fabricated at the polymer concentration of 7.5 wt%${\sim}$15 wt%. It has been found that the average diameter of PAN nanofibers increased with increasing the concentration of PAN solution due to the reduction of whipping and splitting for the high viscosity solution. we also found an evidence that the applied voltage is strongly correlated with the distribution of nanofibers and the uniformed size of nanofibers were obtained at electrostatic value of 1 kV/cm.

• Journal of the Korean Society of Clothing and Textiles
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• v.38 no.3
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• pp.372-385
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• 2014

Lignin is an abundant natural polymer in the biosphere and second only to cellulose; however, it is under-utilized and considered a waste. In this study, lignin was fabricated into nanofibers via electrospinning. The critical parameters that affected the electrospinnability and morphology of the resulting fibers were examined with the aim to utilize lignin as a resource for a new textile material. Poly(vinyl alcohol) (PVA) was added as a carrier polymer to facilitate the fiber formation of lignin, and the electrospun fibers were deposited on polyester (PET) nonwoven substrate. Eleven lignin/PVA hybrid solutions with a different lignin to PVA mass ratio were prepared and then electrospun to find an optimum concentration. Lignin nano-fibers were electrospun under a variety of conditions such as various feed rates, needle gauges, electric voltage, and tip-to-collector distances in order to find an optimum spinning condition. We found that the optimum concentration for electrospinning was a 5wt% PVA precursor solution upon the addition of lignin with the mass ratio of PVA:lignin=1:5.6. The viscosity of the lignin/PVA hybrid solution was determined as an important parameter that affected the electrospinning process; in addition, the interrelation between the viscosity of hybrid solution and the electrospinnability was examined. The solution viscosity increased with lignin loading, but exhibited a shear thinning behavior beyond a certain concentration that resulted in needle clogging. A steep increase in viscosity was also noted when the electrospun system started to form fibers. Consequently, the viscosity range to produce bead-free lignin nanofibers was revealed. The energy dispersive X-ray analysis confirmed that lignin remained after being transformed into nanofibers. The results indicate the possibility of developing a new fiber material that utilizes biomass with resulting fibers that can be applied to various applications such as filtration to wound dressing.

• Journal of the Korean Society of Clothing and Textiles
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• v.37 no.2
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• pp.224-234
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• 2013

This study investigates the fabrication of core-sheath nanocomposite fibers by locating germanium (Ge) and silicon dioxide ($SiO_2$) nanoparticles selectively in the sheath layer by co-axial electrospinning. Co-axially spun fibers were prepared by electrospinning a pure PVA solution and Ge/$SiO_2$/PVA solution as the core and sheath layer, respectively. Core-sheath nanocomposite fibers were electrospun under a variety of conditions that include various feed rates for the core and sheath solutions, voltages, and concentric needle diameters, in order to find an optimum spinning condition. Ge/$SiO_2$ nanocomposite fibers were also prepared by uniaxial electrospinning to compare fiber morphology and nanoparticle distribution with core-sheath nanofibers. Using scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray analysis, it was demonstrated that the co-axial approach resulted in the presence of nanoparticles near the surface region of the fibers compared to the overall distribution obtained for uni-axial fibers. The co-axially electrospun Ge/$SiO_2$/PVA nanofiber webs have possible uses in high efficiency functional textiles in which the nanoparticles located in the sheath region provide enhanced functionality.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.3
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• pp.120-126
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• 2018

In the present study, the multi-nozzle electrospinning process is investigated for the fabrication of uniform polymer nanofiber mats. Electrospinning has been one of the simple and efficient methods to manufacture polymer nanofibers and their mats. Although a typical electrospinning has many advantages such as simple system and operation, various materials, and cost-effectiveness, a relatively low productivity prevents it from being used in practical applications. Thus, the multi-nozzle electrospinning system with the adjustable nozzle position and rotating drum collector is designed and produced in this study. In particular, the effects of the inter-nozzle distance and spatial arrangement of nozzles on the uniformity of the electrospun nanofibers are investigated. With this multi-nozzle electrospinning process, the maximum flow rate of the supplied polymer solution for a uniform electrospinning increases, which indicates the enhanced productivity.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.273-274
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• 2003

Chitin and chitosan have a wide range of application on the environmental and biomedical engineering by their biocompatibility, biodegradability, non-toxicity and adsorption property, etc. The efforts of manufacturing chitosan fibers are continuously maintained until now$\^$l.2)/. Electrospinning is new method to produce the nano-sized fibers for medical uses. Recently, formation of chitosan fiber using electrospinning is studied by many textile researchers. (omitted)

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.1.1-1.1
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• 2011

Electrospinning has known to be very effective tool for production of versatile one-dimensional (1D) nanostructured materials such as nanofibers, nanorod, and nanotubes and for easily assembly to two-, three-dimensional(2D, 3D) nanostructures such as thin film, membrane, and nonwoven web, etc. We have studied on the electrospinning technology for novel energy storage and conversion materials such as advanced separator, dye sensitized solar cell, supercapacitor, etc. High heat-resistive nanofibrous membrane as a new separator for future lithium ion polymer battery was prepared by electrospinning of PVdF based composite solution. The novel nanofibrous composite nonwovens have tensile strength of above 50 MPa and modulus of above 1.3 GPa. The internal structure of the electrospun composite nanofiber with a diameter of few hundreds nanometer were composed of core-shell nanostructure. And also electrospun $TiO_2$ nanorod/nanosphere based dye-sensitized solar cells with high efficiency are successfully prepared. Some battery performance will be introduced.

• Membrane Journal
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• v.15 no.2
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• pp.85-104
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• 2005

Recently, membrane can be prepared by two methods, phase inversion and electrospinning techniques. Phase inversion technique is a conventional but commercially preparation membrane. The most versatile of preparation in this technique is immersion of the cast film into nonsolvent bath, causing dense top layer with a finger-like pattern in the sub layer membrane. The membrane pore size getting from phase inversion is in the range of micro or submicrometer. As a result, it can be used as microfiltration and ultrafiltration applications. A new technique, electrospinning, is introduced for membrane preparation. Nonwoven nanofibrous mat or nanofibrous membrane is obtained. In this technique, electrostatic charge is introduced to the solution jet, causing a thin fiber with high surface area; hence it can be used in the applications where high surface area-to-volume or length-to-diameter ratios are required. Moreover, the pore size can be controlled by controlling the time of electrospinning. Hence, it can be used as a filter for filtering microparticles as well as nanoparticles.