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Full-Text Articles in Engineering
Electrospun Nanofibers For Potential Space-Based Applications, G. Zhang, W. Kataphinan, R. Teye-Mensah, P. Katta, L. Khatri, E. Evans, George Chase, R. Ramsier, Darrell Reneker
Electrospun Nanofibers For Potential Space-Based Applications, G. Zhang, W. Kataphinan, R. Teye-Mensah, P. Katta, L. Khatri, E. Evans, George Chase, R. Ramsier, Darrell Reneker
Darrell Hyson Reneker
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 …
Development Of Carbon Nanofibers From Aligned Electrospun Polyacrylonitrile Nanofiber Bundles And Characterization Of Their Microstructural, Electrical, And Mechanical Properties, Zhengping Zhou, Chuilin Lai, Lifeng Zhang, Yong Qian, Haoqing Hou, Darrell Reneker, Hao Fong
Development Of Carbon Nanofibers From Aligned Electrospun Polyacrylonitrile Nanofiber Bundles And Characterization Of Their Microstructural, Electrical, And Mechanical Properties, Zhengping Zhou, Chuilin Lai, Lifeng Zhang, Yong Qian, Haoqing Hou, Darrell Reneker, Hao Fong
Darrell Hyson Reneker
Carbon nanofibers with diameters of 200–300 nm were developed through stabilization and carbonization of aligned electrospun polyacrylonitrile (PAN) nanofiber bundles. Prior to the oxidative stabilization in air, the electrospun PAN nanofiber bundle was tightly wrapped onto a glass rod, so that tension existed during the stabilization. We also investigated several carbonization procedures by varying final carbonization temperatures in the range from 1000 to 2200 °C. The study revealed that: (1) with increase of the final carbonization temperature, the carbon nanofibers became more graphitic and structurally ordered; (2) the carbon nanofiber bundles possessed anisotropic electrical conductivities, and the differences between the …
Liquid Drop Growth On A Fiber, A. Yarin, George Chase, W. Liu, S. Doiphode, Darrell Reneker
Liquid Drop Growth On A Fiber, A. Yarin, George Chase, W. Liu, S. Doiphode, Darrell Reneker
Darrell Hyson Reneker
A quantitative model is described and verified to predict the growth of oil droplets by coalescence on a single nanofiber. The model considers a stream of fluid carrying many tiny droplets of a different fluid. The mechanisms by which the tiny droplets are captured by a drop growing on a fiber are considered. Different capture mechanisms are examined, including interception, Brownian motion of droplets, and vapor deposition by diffusion. It is shown that droplet interception and Brownian diffusion contribute to drop growth on nanofibers for airborne oil droplets in the size range from 100 to 1000 nm. Merging of growing …
Selective Emitters For Thermophotovoltaics: Erbia-Modified Electrospun Titania Nanofibers, V. Tomer, R. Teye-Mensah, J. Tokash, N. Stojilovic, W. Kataphinan, Edward Evans, George Chase, R. Ramsier, D. Smith, Darrell Reneker
Selective Emitters For Thermophotovoltaics: Erbia-Modified Electrospun Titania Nanofibers, V. Tomer, R. Teye-Mensah, J. Tokash, N. Stojilovic, W. Kataphinan, Edward Evans, George Chase, R. Ramsier, D. Smith, Darrell Reneker
Darrell Hyson Reneker
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 And Spheres By Polymerization Of Cyanoacrylate Monomer, Sphurti Doiphode, Darrell Reneker, George Chase
Nanofibers And Spheres By Polymerization Of Cyanoacrylate Monomer, Sphurti Doiphode, Darrell Reneker, George Chase
Darrell Hyson Reneker
A unique method for creating polymer nanofibers and spheres on a variety of substrates is described. Cyanoacrylate monomer vapor was collected on a solid surface and polymerized to form nanofibers. Tiny spots of initiator on the surface of a substrate and small monomer droplets in a monomer vapor appear to be required for the growth of the polycyanoacrylate nanofibers. The polycyanoacrylate nanofibers create a network and increase the specific surface area significantly.
Carbon Nanotubes On Carbon Nanofibers: A Novel Structure Based On Electrospun Polymer Nanofibers, H. Hou, Darrell Reneker
Carbon Nanotubes On Carbon Nanofibers: A Novel Structure Based On Electrospun Polymer Nanofibers, H. Hou, Darrell Reneker
Darrell Hyson Reneker
No abstract provided.
Electrospinning For Tissue Engineering Scaffolds, J. Lannutti, Darrell Reneker, T. Ma, D. Tomasko, D. Farson
Electrospinning For Tissue Engineering Scaffolds, J. Lannutti, Darrell Reneker, T. Ma, D. Tomasko, D. Farson
Darrell Hyson Reneker
Tissue engineering involves fabrication of three-dimensional scaffolds to support cellular in-growth and proliferation. The goal: generation of ‘neotissues’ that the body can adapt to carry out physiological function. To achieve this generation of scaffolds having tailored, biomimetic (across multiple scales) geometries has become important. The functional complexity of electrospun scaffolds provides significant advantages over other techniques; however, improvements are required before optimal utilization in vivo becomes routine. Cells on such surfaces are sensitive to topography. Electrospinning can be altered to influence either (1) the surface topography of the fibers themselves or (2) the larger topography of the ‘web’ of spun …
Buckling Of Jets In Electrospinning, Tao Han, Darrell Reneker, Alexander Yarin
Buckling Of Jets In Electrospinning, Tao Han, Darrell Reneker, Alexander Yarin
Darrell Hyson Reneker
Various buckling instabilities of electrospinning jets were observed and compared with the buckling instabilities of uncharged fluid jets. Buckling instability arises due to jet compression at impingement on a collector surface and occurs independently of the electrical bending instability. The velocity, diameter, density and viscosity of the electrospinning jets are the key factors that determine the buckling frequency. The electrically charged jets impinging onto grounded, horizontal or inclined (wedge-like) electrodes moving laterally at a constant velocity are studied experimentally. Straight and bending (electrospinning) jets emerge at short and sufficiently long inter-electrode distances, respectively. The experiments show that both straight segment …
Pendulum-Like Motion Of Straight Electrified Jets, Tao Han, Darrell Reneker, Alexander Yarin
Pendulum-Like Motion Of Straight Electrified Jets, Tao Han, Darrell Reneker, Alexander Yarin
Darrell Hyson Reneker
A novel phenomenon, a pendulum-like motion of the usually straight electrified jet was observed experimentally and theoretically modeled. Pendulum-like motion arises due to repulsive Coulomb force between the straight electrified jet and the charges accumulated on the collector. This electrical force repels the similarly charged landing jet segment in the collector plane. The motion is transferred to the whole jet via elastic stress sustained by the jet. The initially straight segment of the jet is arched. The pendulum-like motion has frequencies of the order of 10–102 Hz. The pendulum-like jets were collected onto grounded horizontal electrodes moving laterally at a …
Recycled Expanded Polystyrene Nanofibers Applied In Filter Media, C. Shin, George Chase, Darrell Reneker
Recycled Expanded Polystyrene Nanofibers Applied In Filter Media, C. Shin, George Chase, Darrell Reneker
Darrell Hyson Reneker
In this work polystyrene (PS) nanofibers are electrospun from recycled expanded polystyrene (EPS). These fibers are mixed with micro glass fibers to modify the glass fiber filter media. The filter media are tested in the separation of water droplets from an emulsion of water droplets in oil. Water-in-oil emulsion separations are important to the petrochemical industries for product quality, safety, ecologic and economic reasons. The experimental results in this work show that polystyrene nanofibers with diameters of around 600 nm were produced by the electrospinning method. The addition of the nanofibers to conventional micron sized fibrous filter media improves the …
The Effect Of Nanofibers On Liquid-Liquid Coalescence Filter Performance, C. Shin, George Chase, Darrell Reneker
The Effect Of Nanofibers On Liquid-Liquid Coalescence Filter Performance, C. Shin, George Chase, Darrell Reneker
Darrell Hyson Reneker
A number of factors influence the efficiency and the economics of the separation of dispersed liquid drops in an immiscible liquid–liquid mixture. One important factor that controls the performance of a filter medium in the separation is the fiber size. Electrospun polymer nanofibers have diameters in the nanometer range and are arbitrarily long. The experimental results in this work show that adding nanofibers to conventional micron-sized fibrous filter media improves the separation efficiency of the filter media but also increases the pressure drop. An optimum in the performance occurs (significant increase in efficiency with minimal increase in pressure drop) with …