Branching in Electrospinning of Nanofibers

Electrospinning of polymer nanofibers often begins with a single, straight, elongating, and electrified fluid jet that emanates from a droplet tip when the electric field at the surface is high enough. After some distance an electrically driven bending instability of the elongating jet occurs. For a polymer solution suitable for electrospinning, capillary instability does not cause the jet to become a spray of droplets. Under some conditions, a sequence of secondary jet branches emanates from the primary jet. This paper describes an experiment in which many closely spaced branches along the jet were observed during the electrospinning of a polycaprolactone solution. A theoretical description of the branching phenomenon is proposed. (c) 2005 American Institute of Physics

High-temperature Fiber Matrices: Electrospinning and Rare-earth Modification

We demonstrate the production of nonwoven mats of high-temperature organic and inorganic fibers by electrospinning. Specifically, glass/ceramic (tetraethylorthosilicate-SiO) and fire-blanket (polydiphenoxyphosphazene-PDPP) precursors are electrospun, and the resulting fibers are characterized by scanning electron microscopy, thermogravimetric analysis, and infrared (IR) spectroscopy. We find that the SiO fibers are smaller in diameter and more uniform than the PDPP fibers, and stable to higher temperatures. We also coat these fiber systems with several rare-earth nitrates, and find that these coatings can be used to selectively modify the near-IR spectra of the fibers. This work extends the use of electrospinning into two new classes of materials, and demonstrates that we can subsequently modify the optical properties of the electrospun fibers. (C) 2003 American Vacuum Society

Records of the Franciscan monastery in Našice, vol. 3 (1821-1842) (eds. Tamara Tvrtković – Milan Vrbanus) Hrvatski institut za povijest – Hrvatski institut za povijest – Podružnica za povijest Slavonije, Srijema i Baranje – Zavičajni muzej Našice – Franjevački samostan Sv. Antuna Padovanskoga u Našicama – Grad Našice, Našice – Slavonski Brod – Zagreb, 2017, pp. 520

SiO2 nanofibers have been produced by the electrospinning method by two different approaches: direct spinning of silica precursor-containing nanofibers and spinning of polymer nanofibers followed by sol–gel silica coating. After pyrolysis of the resulting materials, both methods yield silica nanofibers. We extend this work by coating the silica nanofibers with AlN films using a reactive magnetron sputtering technique. Substrate temperature, input gas composition and radio frequency (rf) power are the critical operating parameters for the formation of different crystal structures of the AlN shells. The AlN/SiO2 core-shell heterostructures demonstrate that electrospinning has the potential to produce low-mass, high-surface-area flexible nanofibers for potential space-based applications

Electrospinning of Polymer Nanofibres from Multiple Jets on a Porous Tubular Surface

A novel method for the electrospinning of multiple polymer jets into nanofibres is presented. In this work, 20 wt% nylon 6 solution was electrified and pushed by air pressure through the walls of a porous polyethylene tube. Multiple jets formed on the porous surface and electrospun into nanoscale fibres. The length weighted fibre diameters have a similar mean diameter to those from a single jet but broader in distribution. The mass production rate from the porous tube is 250 times greater than from a typical single jet

Electrospun Bombyx mori gland silk

Solutions of Bombyx mori gland silk can be electrospun with the addition of some polyethylene oxide (PEO). Green fluorescent protein (GFP) can also be incorporated and electrospun without apparent phase separation from the silk. The dimensions of the fibers with and without the GFP are qualitatively similar. The results indicate the possibility of making fibers with uniform non-linear optical properties

High-Temperature Fiber Matrices: Electrospinning and Rare-Earth Modification

We demonstrate the production of nonwoven mats of high-temperature organic and inorganic fibers by electrospinning. Specifically, glass/ceramic (tetraethylorthosilicate-SiO) and fire-blanket (polydiphenoxyphosphazene-PDPP) precursors are electrospun, and the resulting fibers are characterized by scanning electron microscopy, thermogravimetric analysis, and infrared (IR) spectroscopy. We find that the SiO fibers are smaller in diameter and more uniform than the PDPP fibers, and stable to higher temperatures. We also coat these fiber systems with several rare-earth nitrates, and find that these coatings can be used to selectively modify the near-IR spectra of the fibers. This work extends the use of electrospinning into two new classes of materials, and demonstrates that we can subsequently modify the optical properties of the electrospun fibers. (C) 2003 American Vacuum Society

Selective emitters for thermophotovoltaics: erbia-modified electrospun titania nanofibers

Titania nanofibers were synthesized by electrospinning and characterized with scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The nanofibers were annealed to 773 K to achieve the anatase titania crystal structure, and to 1173 K to obtain the rutile phase. In order to create erbia-containing titania nanofibers, erbium (III) oxide particles were added to the pre-cursor solution before electrospinning. After pyrolysis the titania nanofibers supported and encapsulated the erbia particles. Temperature-dependent near-infrared emission spectra demonstrate that the erbia-containing nanofibers emit selectively in the range 6000–7000 cm−1. Because of their large surface to volume ratios and narrow-band optical emission, these nanofibers can be used as selective emitters for thermophotovoltaic applications

Selective Emitters for Thermophotovoltaics: Erbia-modified Electrospun Titania Nanofibers

Titania nanofibers were synthesized by electrospinning and characterized with scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The nanofibers were annealed to 773 K to achieve the anatase titania crystal structure, and to 1173 K to obtain the rutile phase. In order to create erbia-containing titania nanofibers, erbium (III) oxide particles were added to the pre-cursor solution before electrospinning. After pyrolysis the titania nanofibers supported and encapsulated the erbia particles. Temperature-dependent near-infrared emission spectra demonstrate that the erbia-containing nanofibers emit selectively in the range 6000–7000 cm−1. Because of their large surface to volume ratios and narrow-band optical emission, these nanofibers can be used as selective emitters for thermophotovoltaic applications

Erbia-modified electrospun titania nanofibres for selective infrared emitters

Tetraisopropyl titanate (TPT) was mixed with a solution of polyvinylpyrrolidone (PVP) and the solution electrospun into nanofibres. Thermal annealing at 900 °C was used to pyrolyse the PVP, leaving nanofibres of rutile-phase titania. Erbium (III) oxide particles were also added into the solution before electrospinning, and selectively modified the near-infrared optical properties of the titania nanofibres as verified by both absorption and emission spectra. We thereby demonstrate the production of high-temperature optically functionalized nanostructures that can be used in a thermophotovoltaic energy conversion system