Preparation and characterization of coaxial electrospun polysulfone amide/polyurethane

2016 ◽  
Vol 46 (8) ◽  
pp. 1581-1597 ◽  
Author(s):  
Xi Tong ◽  
Xin Bin-Jie

In this study, a novel approach and the related equipment of coaxial electrospinning have been developed to fabricate a new ultrafine polysulfone amide/polyurethane coaxial fibers at nanoscale, with the polysulfone amide as the core and the polyurethane as the shell of the blended fibers. As the co-spinneret has effects on the structure and properties of the spun fiber, three types of co-spinnerets with different diameters were designed to investigate its effects on the fabricated fibers in this research. Three series of polysulfone amide/polyurethane coaxial fibers were spun using the self-developed coaxial electrospinning equipment, and these fibers were characterized systematically using scanning electron microscope, transmission electron microscope, X-ray diffraction, differential scanning calorimeter and thermogravimetric. High-speed photography was used to digitalize the image of the tailor cone and jet motion of polymer fluid during the spinning process, which provides a detailed description of the electrospinning for the further theoretical analysis. The three-dimensional electric field simulation was also carried out to model the differences of electric field. Our experimental results show that the mechanical and thermal properties of the core–shell fibers fabricated in this research have been improved in the comparison with the fibers spun using the conventional single-needle electrospinning method. The composite fibers have the core–shell structure, so that it can combine the excellent thermal properties of the polysulfone amide and the excellent mechanical properties of the polyurethane. The newly developed polysulfone amide/polyurethane fiber could be used in the field of industrial textiles; it has the potential applications for the development of high-performance apparels in the future.

e-Polymers ◽  
2017 ◽  
Vol 17 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Yong-Hui Wu ◽  
Deng-Guang Yu ◽  
Hai-Peng Li ◽  
Xiang-Yang Wu ◽  
Xiao-Yan Li

AbstractA new type of medicated polymeric composite consisting of acyclovir (ACY), polyvinylpyrrolidone K60 (PVP) and polyethylene glycol 6000 (PEG) with core-shell structure were prepared by a coaxial electrospinning process. The composites could enhance the dissolution of the poorly water-soluble drug. The shell layers were formed from a spinnable working fluid containing the filament-forming PVP and citric acid while the core parts were prepared from an un-spinnable co-dissolving solution composed of ACY, sodium hydrate and PEG. Scanning electron microscope and transmission electron microscope observations demonstrated that the composites had a homogeneous linear topography with a slippery surface, a diameter of 670±130 nm, and an obvious core-shell structure. X-ray diffraction (XRD) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy results demonstrated that the drug and citric acid contained in the core and shell parts were in an amorphous status. In vitro dissolution experiments exhibited that ACY was able to be free within 1 min, and the dissolution media were neutral due to acid-basic action within the core-shell structures. The medicated nanocomposites resulted from a combined usage of hydrophilic polymeric excipients PVP and PEG could provide a new solution to the problem associated with the dissolution of poorly water-soluble drugs.


1968 ◽  
Vol 33 (4) ◽  
pp. 446-478 ◽  
Author(s):  
Don E. Crabtree

AbstractThis paper deals with the results of the author"s attempts to replicate the obsidian polyhedral cores and prismatic blades of Mesoamerica. Blades have been produced by the direct percussion, indirect percussion, and pressure methods. The pressure method using a chest crutch and a clamp produces cores and blades which are true replicas of aboriginal specimens. The importance of preforming the core and of platform preparation is stressed, and it is pointed out that, usually, actual removal of the blade offers few problems. However, to produce exhausted cores which show the perfection of aboriginal specimens and a large series of nearly identical blades requires good muscular coordination, high quality material, the establishment of patterns or rhythms of motor habits, and the absence of distractions. The author also discusses the difficulties of recovering from mistakes in manufacture.High-speed photography of prismatic blade removal, at 5,000 frames per second, has helped illustrate the behavior of the material and of the stoneworker. These photographs also indicate that under the present experimental and photographic conditions the author (Crabtree) is able to remove a prismatic blade from a core in about 1,250th of a second.


2019 ◽  
Vol 54 (15) ◽  
pp. 1961-1976
Author(s):  
Xu Xiangmin ◽  
Hongxiang Zhang ◽  
Tong Beibei ◽  
Li Binjie ◽  
Yudong Zhang

The advanced multifunctional filler has become one of the main challenges in developing high-performance polymer composites. In this study, the acid-treated multiwall carbon nanotubes (MWCNTs) were adhered to the surface of milled glass fiber under the combined effect of 3-aminopropyltriethyloxy silane and tetraethyl orthosilicate to fabricate a hierarchical fiber (MWCNTs-MGF). The morphologies of the hierarchical fibers were characterized using field-emission scanning electron microscope and transmission electron microscope, which showed evidence of a coating layer of MWCNTs on each fiber surface. The MWCNTs-MGF was employed as a multifunctional filler to prepare polyoxymethylene-based composites using a twin-screw extruder by melt blending. The obtained composites exhibited improved mechanical and thermal properties. The composite tensile strength and notched impact strength and Young's modulus increased by 10%, 32%, and 32%, respectively, as the MWCNTs-MGF content varies from 0 to 10 wt.%. Meanwhile, the reinforcing and toughing mechanisms of MWCNTs-MGF were also elaborated by analyzing the interfacial adhesion and fracture morphologies of the composites. Moreover, the study on thermal stability and crystallization behavior indicated that the polyoxymethylene/MWCNTs-MGF composites had higher thermal stability, crystallization temperature, and crystallinity as compared to the polymer matrix. The improvement of thermal stability originates from the unique surface structure of MWCNTs-MGF, while the increase in crystallization temperature and crystallinity is due to the strong heterogeneous nucleation ability of the hierarchical fibers.


2014 ◽  
Vol 693 ◽  
pp. 394-399 ◽  
Author(s):  
Lucie Vysloužilová ◽  
Jan Valtera ◽  
Karel Pejchar ◽  
Jaroslav Beran ◽  
David Lukáš

The paper is focused on the design of the electrode for needleless coaxial electrospinning. This method allows to produce core/shell nanofibers from the free surface of a polymeric two-layer. The geometry of the designed model of electrode was analyzed using the software Autodesk Simulation Multiphysics. The results of electrostatic field simulation indicate the sharp edges of the electrode as the source of high electric intensity. These sharp edges lead to the loss of the electric energy during the electrospinning process. Based on that, the new cylindrical geometry of the electrode was developed. The results of carried out experiments clearly demonstrate the enhancement of the electrospinning process stability.


NANO ◽  
2014 ◽  
Vol 09 (04) ◽  
pp. 1450051
Author(s):  
ASHWANI VERMA ◽  
BAHNIMAN GHOSH ◽  
AKSHAY KUMAR SALIMATH

In this paper, we have used semiclassical Monte Carlo method to show the dependence of spin relaxation length in III–V compound semiconductor core–shell nanowires on different parameters such as lateral electric field, temperature and core dimensions. We have reported the simulation results for electric field in the range of 0.5–10 kV/cm, temperature in the range of 77–300 K and core length ranging from 2 nm to 8 nm. The spin relaxation mechanisms used in III–V compound semiconductor core–shell nanowire are D'yakonov–Perel (DP) relaxation and Elliott–Yafet (EY) relaxation. Depending upon the choice of materials for core and shell, nanowire forms two types of band structures. We have used InSb – GaSb core–shell nanowire and InSb – GaAs core–shell nanowire and nanowire formed by swapping the core and shell materials to show all the results.


2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Maryam Haghighi ◽  
Mehranoosh Fereidooni

In this study, ZSM-22 was synthesized using N,N-diethylaniline as a template through a hydrothermal method. The proton and various metals such as zirconium, strontium, and iron were immobilized on the surface of obtained zeolites through the ion exchange method. The catalysts were studied by Fourier-Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), Brunauer–Emmett–Teller (BET) adsorption isotherms, Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM), Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) elemental analysis, and Temperature-Programmed Desorption of ammonia (TPD-NH3) technique for determining the number of acid sites. In the esterification reaction of oleic acid, the operating conditions such as catalyst dosage, temperature, molar ratio of methanol to oil, and reaction time were optimized and adjusted at 11 wt%, 70°C, 10 : 1, and 48 h subsequently. The maximum yield% of 48.07% was achieved in the presence of Zr-H-ZSM-22 at optimum conditions. In order to improve the efficiency of three zeolites Zr-H-ZSM-22, Fe-H-ZSM-22, and Sr-H-ZSM-22, the core-shell structures with SiO2 coating were prepared. Zr-H-ZSM-22@SiO2 was less active than Zr-H-ZSM-22 due to the SiO2 coverage of Lewis active sites.


2021 ◽  
Vol 0 (0) ◽  
pp. 0
Author(s):  
Zhiwen Zhao

<p style='text-indent:20px;'>In the perfect conductivity problem arising from composites, the electric field may become arbitrarily large as <inline-formula><tex-math id="M1">\begin{document}$ \varepsilon $\end{document}</tex-math></inline-formula>, the distance between the inclusions and the matrix boundary, tends to zero. In this paper, by making clear the singular role of the blow-up factor <inline-formula><tex-math id="M2">\begin{document}$ Q[\varphi] $\end{document}</tex-math></inline-formula> introduced in [<xref ref-type="bibr" rid="b27">27</xref>] for some special boundary data of even function type with <inline-formula><tex-math id="M3">\begin{document}$ k $\end{document}</tex-math></inline-formula>-order growth, we prove the optimality of the blow-up rate in the presence of <inline-formula><tex-math id="M4">\begin{document}$ m $\end{document}</tex-math></inline-formula>-convex inclusions close to touching the matrix boundary in all dimensions. Finally, we give closer analysis in terms of the singular behavior of the concentrated field for eccentric and concentric core-shell geometries with circular and spherical boundaries from the practical application angle.</p>


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