Properties of electrospun nanofibers

The properties of developed electrospun nanofibers are key issues for then-applications in industry. Here, the structure and morphology of the nanofibers were characterized by field emission scanning electron microscopy, transmission electron microscopy. X-ray powder diffraction, and their electromagnetic interference shielding effectiveness and magnetic property were also evaluated for electromagnetic shielding applications. 

The CoFe204/PAN nanofibers were fabricated prior to the fabrication of PAN fibers containing carbon nanotubes and cobalt ferrite. The FESEM image of synthesized CoFe204 particles is shown in Fig. 7.3. Particles with a diameter of 10-25 nm are observed, with their irregular shapes attributable to aggregation and surfactant-free conditions. 

3 FESEM image of CoFg204 particles synthesized by hydrothermal method. 

During CoFe204/PAN nanofiber preparation, the diameter distribution was controlled at 200-400 nm for all of the CoFe204 loadings. 

A uniform dispersion of CNTs in the electrospinning solution is critical for fabricating nano-composite fibers. Poorly dispersed CNTs always yield beaded morphologies, even at low concentrations. However, van derWaals forces cause these CNTs to readily aggregate, making dispersion in liquid difficult. To overcome this problem, the CNTs were treated with concentrated nitric acid, which has proven to be an effective method for improving the dispersion of CNTs in liquid.  

Schreuder-Gibson et al used nylon-6,6 (N6,6), polybenzimidazole (FBI) and poly(tetrafluoroethylene) membranes produced from electrospun fibers as protective layers. They measured properties of these electrospun membranes, including structural effects upon moisture transport, air convection, aerosol filtration, porosity and tensile strength. 

Dersch et showed that the intrinsic structure of N6 and poly(lactic acid) fibers do not differ to an appreciable extent from those found for much 

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Figure 4.16 PL spectra of (a) 20 wt% PMO-PPV/PMMA eletrospun fibers and net PMO-PPV films, and (b) 20 wt% Eu(ODBM) pben/PMMA eletrospun fibers and net Eu(ODBM)3phen films (c) fluorescent optical microscope images of 20 wt% PMO-PPV/PMMA and (d) 20 wt% Eu(ODBM)3phen/PMMA eletrospun fibers on a quartz flake. (Reprinted with permission from Materials Letters, Preparation and photoluminescence properties of electrospun nanofibers containing PMO-PPV and Eu(ODBM)jphen byS. Tan, X. Feng, B. Zhao etal., 62, 2419-2421. Copyright (2008) Elsevier Ltd)...

M. Kotaki, X-M. Liu, and C. He, Optical properties of electrospun nanofibers of conducting polymer-based blends, J. Nanosci. NanotechnoL, 6, 3997-4000 (2006). 

Asmatulu R, Khan W and Yildirim M B (2009) Acoustical Properties of Electrospun Nanofibers... 

The PAN solution in DMF were electrospun under different conditions, including various PAN solution concentrations, applied voltages, volume flow rates and tip to collector distances, to study the effect of electrospinning parameters on the morphology and properties of electrospun nanofibers. 

Measuring the effects of different spinning conditions and the use of high molecular weight polymers on the properties of electrospun nanofibers... 

Improving the properties of electrospun nanofibers experimental results... 

Fee TJ, Dean DR, Eberhaidt AW, Berry JL (2012) A novel device to quantify the mechanical properties of electrospun nanofibers. J Biomech Eng 134 104503... 

Zhang, F., Zhang, Z., Liu, Y., Leng, J., 2014. Shape memory properties of electrospun Nafion nanofibers. Fibers and Polymers 15 (3), 534—539. 

Figure 4.10 SEM micrographs of electrospun nanofibers from (a) aqueous solutions of 1.5 wt% PEO as carrier with PPy content of 71.5 wt%, (b) 7.5wt% [(PPy3) (DEHS) ]x solution in DMF. The scale bar is Igm. (Reprinted with permission from Polymer, Conductive polypyrrole nanofibers via electrospinning Electrical and morphological properties by I. S. Chronakis, S. Grapenson and A. Jakob, 47, 1597-1603. Copyright (2006) Elsevier Ltd)...

This review covers the active research area of processing functional conductive nanofibers and nanostructures with various compositions and properties by means of the electrospinning method. It is also focuses on the unique properties of electrospun conductive nanostructures that can be utilized to improve existing applications of conductive materials and on the various possibilities to meet the requirements of a number of novel applications. 

Y-W. Ju, G-R. Choi, H-R. Jimg, and W-J. Lee, Electrochemical properties of electrospun PAN/MWCNT carbon nanofibers electrodes coated with polypyrrole, Electrochim. Acta, 53, 5796-5803 (2008). 

Wee, G., H. Z. Soh, Y. L. Cheah, S. G. Mhaisalkar, and M. Srinivasan. 2010. Synthesis and electrochemical properties of electrospun V2O5 nanofibers as supercapacitor electrodes. Journal of Materials Chemistry 20 6720-6725. 

Wei Z, Zhang Q, Wang L, Peng M, Wang X, long S, et al. The preparation and adsorption properties of electrospun aramid nanofibers. J Polym Sci Part B Polym Phys 2012 50(20) 1414-20. 

The need for mechanical reinforcement has been the driving force for most of the reported work on polymer/CNT composites. In an attempt to investigate the mechanical properties of electrospun PAN/SWNT nanofibers, Ko et al. (75) have used an atomic force microscope (AFM) to measure the elastic modulus of the electrospun composite nanofibers. The obtained fiber modulus was 140 GPa, a value which is much higher than that of conventional PAN fibers (60 GPa) (75). In a somewhat related but independent study, Mathew et al. (92) also used AFM to measure the mechanical properties of electrospun polybutylene/MWNT terephthalate nanofibers. Elastic deformation of MWNTs in electrospun PEO/MWNT and PVA/MWNT nanofibers was studied by Zhou and co-workers (84), and was found to increase with an increase in the modulus of the polymer matrix. In the same study, a simplified model was also proposed to estimate the elastic modulus ratio of MWNT and polymers. To confirm the validity of their model, these authors compared the model predictions with experimental data obtained from AFM measurements. 

Bellan et al. (2006) electrospun blended PEG and DNA and demonstrated the ability to produce polymeric nanofibers containing isolated stretched DNA molecules. The embedded DNA molecules were imaged with fluorescence microscopy by incorporating a dilute concentration of fluorescently labeled DNA molecules into an electrospinning process. The direct observation of the degree to which the DNA molecules had been stretched could give information on the fluid dynamic behavior of the jet and the mechanical properties of the nanofibers. 

Cay, A. and Miraftab, M. (2013) Properties of electrospun poly(vinyl alcohol) hydrogel nanofibers crosslinked with 1,2,3,4-butanetetracarboxylic acid. J. 

Chun et al. [93] produced carbon nano fibers with diameter in the range from 100 nm to a few microns from electrospim polyacrylonitrile and me-sophase pitch precursor fibers. Wang et al. [94, 95] produced carbon nanofibers from carbonizing of electrospun PAN nanofibers and studied their structure and conductivity. Hou et al. [96] reported a method to use the carbonized electrospun PAN nanofibers as substrates for the formation of multiwall carbon Nanotubes. Kim et al. [14, 97] produced carbon nanofibers from PAN-based or pitch-based electrospim fibers and studied the electrochemical properties of carbon nanofibers web as an electrode for supercapacitor. 

Im JS, Bai BC, Bae TS, In SJ, Lee YS (2011) Improved anti-oxidation properties of electrospun polyurethane nanofibers achieved by oxyfluorinated multi-walled carbon nanotubes and aluminum hydroxide. Mater Chem Phys 126 685-692... 

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