The Experts below are selected from a list of 81 Experts worldwide ranked by ideXlab platform
Eyal Zussman - One of the best experts on this subject based on the ideXlab platform.
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Estimating the Degree of Polymer Stretching during Electrospinning: An Experimental Imitation Method
Macromolecular Materials and Engineering, 2017Co-Authors: Gleb Vasilyev, Arkadii Arinstein, Michael Burman, Eyal ZussmanAbstract:It is commonly accepted that a polymer matrix inside Electrospun nanofibers is in a stretched nonequilibrium state. This state develops as a result of significant elongation of the Electrospun Jet, at a high stretching rate. Due to high deformation level, the entangled polymer network in the Jet experiences noticeable topological reorganization, meaning that the electrospinning is accompanied by both elastic and plastic deformations. Despite possible relaxation in the final state of polymer nanofibers due to some residual solvent, they remain noticeably stretched. Measurement or estimation of the resulting degree of stretching is still challenging. In this paper, an experimental method is proposed to estimate the degree of stretching, and Electrospun nanofibers made of thermoplastic polyurethane (TPU) segmented block-copolymer are demonstrated. The rationale of this method is based on the similarity in the behavior of Electrospun TPU nanofibers, and stretched cast TPU films; both demonstrate massive contraction upon heating. By comparing the degree of contraction of the nanofibers and the films, the level of polymer network stretching (both elastic and plastic) during electrospinning can be estimated. Depending on the strength of the applied electrostatic field, the degree of stretching of Electrospun fibers is found to be noticeably increased in TPU.
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The role of interfacial viscoelasticity in the stabilization of an Electrospun Jet
Polymer, 2010Co-Authors: Omri Regev, Steven Vandebril, Eyal Zussman, Christian ClasenAbstract:Abstract Stabilization of the Jet is necessary for the successful fabrication of continuous fibers from solutions via electrospinning. Although intensively studied over the past decade, the mechanisms underlying Jet stabilization are still not precisely understood. The traditional explanation for Jet stabilization emphasizes the role of the elastic response of the polymer coil in creating a sufficiently high extensional viscosity, which prevents the breakup of the filament under extension. However, comprehensive rheological studies of bovine serum albumin (BSA) solutions that can be Electrospun into continuous fibers show an absence of any significant bulk elasticity in shear and extension that would account for the stabilization of the Jet. In order to explain this discrepancy, it is proposed that a complex Jet structure, composed of a liquid core surrounded by a viscoelastic interface, is formed during the spinning process, where the surface viscoelasticity is responsible for the Jet stabilization. These rheological properties of the surface are experimentally verified using novel interfacial rheometry. It is also shown that the surface viscoelasticity is further enhanced by varying the protein conformation (unfolding), as well as its concentration in solution.
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carbon nanotubes embedded in oriented polymer nanofibers by electrospinning
Langmuir, 2003Co-Authors: Yael Dror, Wael Salalha, Rafail Khalfin, Yachin Cohen, And Alexander L Yarin, Eyal ZussmanAbstract:The electrospinning process was used successfully to fabricate nanofibers of poly(ethylene oxide) (PEO) in which multiwalled carbon nanotubes (MWCNT) are embedded. Initial dispersion of MWCNTs in water was achieved using amphiphiles, either as small molecules (sodium dodecyl sulfate, SDS) or as a high molecular weight, highly branched polymer (Gum Arabic). These dispersions provided separation of the MWCNTs and their individual incorporation into the PEO nanofibers by subsequent electrospinning. The focus of this work is on the development of axial orientations in these multicomponent nanofibers. A theoretical model is presented for the behavior of rodlike particles representing CNTs in electrospinning. Initially the rods are randomly oriented, but due to the sinklike flow in a wedge they are gradually oriented mainly along the stream lines, so that straight CNTs are almost oriented upon entering the Electrospun Jet. The degrees of orientation of polymer, surfactant, and MWCNT were studied using X-ray dif...
Christian Clasen - One of the best experts on this subject based on the ideXlab platform.
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The role of interfacial viscoelasticity in the stabilization of an Electrospun Jet
Polymer, 2010Co-Authors: Omri Regev, Steven Vandebril, Eyal Zussman, Christian ClasenAbstract:Abstract Stabilization of the Jet is necessary for the successful fabrication of continuous fibers from solutions via electrospinning. Although intensively studied over the past decade, the mechanisms underlying Jet stabilization are still not precisely understood. The traditional explanation for Jet stabilization emphasizes the role of the elastic response of the polymer coil in creating a sufficiently high extensional viscosity, which prevents the breakup of the filament under extension. However, comprehensive rheological studies of bovine serum albumin (BSA) solutions that can be Electrospun into continuous fibers show an absence of any significant bulk elasticity in shear and extension that would account for the stabilization of the Jet. In order to explain this discrepancy, it is proposed that a complex Jet structure, composed of a liquid core surrounded by a viscoelastic interface, is formed during the spinning process, where the surface viscoelasticity is responsible for the Jet stabilization. These rheological properties of the surface are experimentally verified using novel interfacial rheometry. It is also shown that the surface viscoelasticity is further enhanced by varying the protein conformation (unfolding), as well as its concentration in solution.
Baojiu Chen - One of the best experts on this subject based on the ideXlab platform.
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Ultralong well-aligned TiO 2 :Ln 3+ (Ln = Eu, Sm, or Er) fibres prepared by modified electrospinning and their temperature-dependent luminescence
Scientific reports, 2017Co-Authors: Yang Song, Lan Xijie, Shimin Liu, Yanning Tang, Baojiu ChenAbstract:Electrospinning has emerged as an attractive technique for the fabrication of ultrafine fibres in micro-/nano-scale fineness: however, it remains a significant technological challenge to assemble aligned fibre arrays via an conventional electrospinning method due to the inherent whipping instability of the polymeric Jet. We herein have first developed a simple modified electrospinning method with which to prepare ultralong (>300 mm) well-aligned inorganic fibre arrays, i.e., using an ultrahigh molecular weight polymer to suppress or eliminate the whipping motion of the Electrospun Jet, has emerged as a facile approach for the continuous fabrication of well-aligned, ultralong fibres through simply using a rotating cylinder as the collector (it was not found necessary to use a very high rotating speed, extra magnetic, electrical field) in the electrospinning process. As result, the ultralong well-aligned TiO2:Ln3+ (Ln = Eu, Sm, or Er) fibre arrays can be obtained from ultrahigh molecular weight poly(ethylene oxide), tetra-n-butyl titanate (Ti(OC4H9)4) and lanthanide nitrate in the modified electrospinning approach. The grow mechanism and luminescent properties of these ultralong well-aligned TiO2:Ln3+ fibre arrays were also investigated.
Omri Regev - One of the best experts on this subject based on the ideXlab platform.
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The role of interfacial viscoelasticity in the stabilization of an Electrospun Jet
Polymer, 2010Co-Authors: Omri Regev, Steven Vandebril, Eyal Zussman, Christian ClasenAbstract:Abstract Stabilization of the Jet is necessary for the successful fabrication of continuous fibers from solutions via electrospinning. Although intensively studied over the past decade, the mechanisms underlying Jet stabilization are still not precisely understood. The traditional explanation for Jet stabilization emphasizes the role of the elastic response of the polymer coil in creating a sufficiently high extensional viscosity, which prevents the breakup of the filament under extension. However, comprehensive rheological studies of bovine serum albumin (BSA) solutions that can be Electrospun into continuous fibers show an absence of any significant bulk elasticity in shear and extension that would account for the stabilization of the Jet. In order to explain this discrepancy, it is proposed that a complex Jet structure, composed of a liquid core surrounded by a viscoelastic interface, is formed during the spinning process, where the surface viscoelasticity is responsible for the Jet stabilization. These rheological properties of the surface are experimentally verified using novel interfacial rheometry. It is also shown that the surface viscoelasticity is further enhanced by varying the protein conformation (unfolding), as well as its concentration in solution.
Lei Zhai - One of the best experts on this subject based on the ideXlab platform.
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Polymer-derived ceramic composite fibers with aligned pristine multiwalled carbon nanotubes.
ACS applied materials & interfaces, 2010Co-Authors: Sourangsu Sarkar, Jianhua Zou, Jianhua Liu, Lei ZhaiAbstract:Polymer-derived ceramic fibers with aligned multiwalled carbon nanotubes (MWCNTs) are fabricated through the electrospinning of polyaluminasilazane solutions with well-dispersed MWCNTs followed by pyrolysis. Poly(3-hexylthiophene)-b-poly (poly (ethylene glycol) methyl ether acrylate) (P3HT-b-PPEGA), a conjugated block copolymer compatible with polyaluminasilazane, is used to functionalize MWCNT surfaces with PPEGA, providing a noninvasive approach to disperse carbon nanotubes in polyaluminasilazane chloroform solutions. The electrospinning of the MWCNT/polyaluminasilazane solutions generates polymer fibers with aligned MWCNTs where MWCNTs are oriented along the Electrospun Jet by a sink flow. The subsequent pyrolysis of the obtained composite fibers produces ceramic fibers with aligned MWCNTs. The study of the effect of polymer and CNT concentration on the fiber structures shows that the fiber size increases with the increment of polymer concentration, whereas higher CNT content in the polymer solutions l...