Positioning and Aligning Electrospun PAN Fibers by Conductive and Dielectric Substrate Patterns (original) (raw)
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Electrospinning of polyacrylonitrile nanofibers
Journal of applied polymer science, 2006
Polyacrylonitrile (PAN) was electrospun in dimethylformamide as a function of electric field, solution flow rate, and polymer concentration (C). The fiber diameter increased with C and ranged from 30 nm to 3.0 mm. The fiber diameter increased with the flow rate and decreased when the electric field was increased by a change in the working distance; however, it did not change significantly when the electric field was varied by a change in the voltage at a given working distance. The fibers below about 350 nm diameter contained beads, whereas above this diameter, bead-free fibers were obtained. For PAN with a molecular weight of 100,000 g/mol, the fiber diameter scaled as C 1.2 and C 7.5 at low (5.1-16.1 wt %) and high (17.5-22.1 wt %) C values, respectively. Both concentrations were in the semidilute entangled regime, where the specific viscosity scaled as C 4.4 , consistent with De Gennes's scaling concepts. In the semidilute unentangled regime (0.5-3.1 wt %), where the viscosity scaled as C 1.3 , microscopic or nanoscopic particles rather than fibers were obtained. Concentrationdependent electrospinning studies were also carried out for higher molecular weight PAN (250,000 and 700,00 g/mol). The results of these studies are also presented and discussed.
Fundamental parameters affecting electrospinning of PAN nanofibers as uniaxially aligned fibers
Journal of Applied Polymer Science, 2006
Electrospinning with a collector consisting of two pieces of electrically conductive substrates separated by a gap has been used to prepare uniaxially aligned PAN nanofibers. Solution of 15 wt % of PAN/DMF was used tentatively for electrospinning. The effects of width of the gap and applied voltage on degree of alignment were investigated using image-processing technique by Fourier power spectrum method. The electrospinning conditions that gave the best alignment of nanofibers for 10 -15 wt % solution concentrations were experimentally obtained. Bundles like multifilament yarns of uniaxially aligned nanofibers were prepared using a new simple method. After-treatments of these bundles were carried out in boiling water under tension. A comparison was made between the crystallinity and mechanical behavior of posttreated and untreated bundles.
Nanomedicine Research Journal, 2017
Since the electric field is the main driving force in electrospinning systems, the modeling and analysis of electric field distribution are critical to the nanofibers production. The aim of this study was modeling of the electric field and investigating the various parameters on polyacrylonitrile (PAN) nanofibers morphology and diameter. Methods: The electric field profile at the nozzle and electrospinning zone was evaluated by Finite Element Method. The morphology and diameter of nanofibers were examined by Scanning electron microscopy (SEM). Results: The results of the electric field analysis indicated that the electric field was concentrated at the tip of the nozzle. Moreover, in the spinning direction, the electric field was concentrated at the surface of the spinneret and decayed rapidly toward the surface of the collector. Increasing polymer solution concentration from 7 to 11wt.% led to increasing nanofibers diameter form 77.76 ± 19.44 to 202.42 ± 36.85. Conclusions: Base on our results, it could be concluded that concentration of the electric field at the tip of the nozzle is high and initiates jet and nanofibers formation. PAN nanofibers can be transformed to carbon nanofibers which have various applications in biomedicine.
A study on electrospinning of polyacrylonitrile nanofibers
Korean Journal of Chemical Engineering, 2010
Aligned and molecularly oriented Polyacrylonitrile (PAN) nanofibers were prepared using a non-conventional approach. Various take up velocity of rotating drum was examined for increasing of productivity, alignment and mechanical properties of nanofibers. Impressive techniques like Raman spectroscopy were utilized for characterization of nanofibers.
Journal of the Textile Institute, 2007
ABSTRACT Electrospinning is a process that produces nanofiber through the action of an external electric field imposed on a polymer solution or melt. This paper introduces a new system capable of producing continuous uniaxially aligned PAN nanofiber yarn by manipulating the electric field. The manipulation was carried out by employing a negative charged bar in the electric field of conventional electrospinning system, leading to the formation of an electrostatic multipolar field. As a result, the main stream was redirected towards a rotating take up unit, collecting the twisted yarn consisting of uniaxially aligned nanofibers. The yarns were then treated in boiling water under tension and their mechanical properties were compared with those of the untreated ones.
Materials & Design, 2008
Effects of material and process parameters on the diameter of electrospun polyacrylonitrile fibers were experimentally investigated. Response surface methodology (RSM) was utilized to design the experiments at the settings of solution concentration, voltage and the collector distance. It also imparted the evaluation of the significance of each parameter on the resultant fiber diameter. The investigations were carried out in the two-variable process domains of several collector distances as applied voltage and the solution concentration were varied at a fixed polymer molecular weight. The mean diameter and coefficient of variation were modeled by polynomial response surfaces as functions of solution concentration and voltage at each collector distance. Effect of applied voltage in micron-scale fiber diameter was observed to be almost negligible when solution concentration and collector distance were high. However, all three factors were found statistically significant in the production of nano-scale fibers. The response surface predictions revealed the parameter interactions for the resultant fiber diameter, and showed that there is a negative correlation between the mean diameter and coefficient of variation for the fiber diameter. A sub-domain of the parameter space consisting of the solution concentration, applied voltage and collector distance, was suggested for the potential nano-scale fiber production. (O.S. Yö rdem), mpapila@sabanciuniv.edu (M. Papila), yusufm@sabanciuniv.edu (Y.Z. Menceloglu). 1 Tel.: +90 216 483 9000/2079; fax: +90 216 483 9550. 2 Tel.: +90 216 483 9535; fax: +90 216 483 9550. www.elsevier.com/locate/matdes Materials and Design xxx (2007) xxx-xxx Materials & Design ARTICLE IN PRESS Please cite this article in press as: Yö rdem OS et al., Effects of electrospinning parameters on polyacrylonitrile .
Development and characterization of highly oriented PAN nanofiber
Brazilian Journal of Chemical Engineering, 2010
A simple and non-conventional electrospinning technique was employed for producing highly oriented Polyacrylonitrile (PAN) nanofibers. The PAN nanofibers were electrospun from 14 wt% solution of PAN in dimethylformamid (DMF) at 11 kv on a rotating drum with various linear speeds from 22.5 m/min to 67.7 m/min. The influence of take up velocity was investigated on the degree of alignment, internal structure and mechanical properties of collected PAN nanofibers. Using an image processing technique, the best degree of alignment was obtained for those nanofibers collected at a take up velocity of 59.5 m/min. Moreover, Raman spectroscopy was used for measuring molecular orientation of PAN nanofibers. Similarly, a maximum chain orientation parameter of 0.25 was determined for nanofibers collected at a take up velocity of 59.5 m/min.
This paper explores the effect of solution and electrospinning parameters on the morphology, mechanical properties and surface characteristics of Polyacrylonitrile (PAN) electrospun nanofiber mats. PAN/DMF (Dimethylformamide) solutions with different concentrations were electrospun under various parameters. The results show that the average fiber diameter increase from 208 nm to 881 nm with an increase in PAN concentration from 6 wt% to 12 wt%. Feed rate has inconsistent trend on the fiber diameter; however with increasing feed rate from 0.8 ml/hr to 1.4 ml/hr, the average fiber diameter more than doubledfrom400nm to 895nm. Average fiber diameter decreased slightly from 383 nm to 332 nm up to a certain threshold value of voltage, and then increased significantly to 750 nm when voltage was increased beyond this threshold. Somewhat surprisingly, when the distance between needle tip and collector was increased from 100mm to 150 mm, average fiber diameter increased almost four times (20...
World Academy of Science, Engineering and Technology International Journal of Electrical and Computer Engineering, 2019
Electrospinning is the most widely utilized method to create nanofibers because of the direct setup, the capacity to mass-deliver consistent nanofibers from different polymers, and the ability to produce ultrathin fibers with controllable diameters. Smooth and much arranged ultrafine Polyacrylonitrile (PAN) nanofibers with diameters going from submicron to nanometer were delivered utilizing Electrospinning technique. PAN powder was used as a precursor to prepare the solution utilized as a part of this process. At the point when the electrostatic repulsion contradicted surface tension, a charged stream of polymer solution was shot out from the head of the spinneret and along these lines ultrathin nonwoven fibers were created. The effect of electrospinning parameter such as applied voltage, feed rate, concentration of polymer solution and tip to collector distance on the morphology of electrospun PAN nanofibers were investigated. The nanofibers were heat treated for carbonization to examine the changes in properties and composition to make for electrical application. Scanning Electron Microscopy (SEM) was performed before and after carbonization to study electrical conductivity and morphological characterization. The SEM images have shown the uniform fiber diameter and no beads formation. The average diameter of the PAN fiber observed 365nm and 280nm for flat plat and rotating drum collector respectively. The four probe strategy was utilized to inspect the electrical conductivity of the nanofibers and the electrical conductivity is significantly improved with increase in oxidation temperature exposed.
A Brief Review of Electrospinning of Polymer Nanofibers: History and Main Applications
Journal of New Materials for Electrochemical Systems, 2020
Electrospinning is an intensely facile methodology for the precise manufacturing of polymer nanofibers by manipulation of electrostatic force, which stunts like a driving force. In this technique, fibers produced with a diameter range between 50 to 500 nm. Two practices are made up by the scientists for electrospinning of versatile polymer. Polymers can be electrospun into ultrafine fibers in solvent solution or melt form. Tremendous progress had been made in this field in the past, and numerous applications were inaugurated. It’s a field of nanotechnology which rapidly growing due to enormous potential in creating novel applications regarding morphologies, materials structure, surface area, porosity, and Reinforcement in nanocomposite development. Fibers can be assembled in the form of nonwoven, aligned, patterned, random three-dimensional structures and sub-micron fibers. Many complications faced during electrospinning, for example, control the morphology and structure of Nanofibe...