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Spinning Solution (spinning + solution)
Selected AbstractsStructure and properties of regenerated Antheraea pernyi silk fibroin filamentsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2009Baoqi Zuo Abstract Degummed Antheraeapernyi silk fibroin (APSF) fibers were dissolved in a lithium thiocyanate solution that was dialyzed against distilled water for 3 days. Solution-cast APSF films were dissolved in hexafluoroisopropanol to prepare a spinning solution. Wet spinning was employed to prepare APSF filaments. Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, solid-state 13C cross-polarization/magic angle spinning nuclear magnetic resonance, and differential scanning calorimetry were employed to study the regenerated APSF filaments. The results showed a uniform distribution of molecular weights, and the largest one may have been greater than 200 kDa. The regenerated filaments contained ,-sheet, ,-helix, and random-coil conformations, and their breaking strength was 52.20% of the breaking strength of the native fibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Preparation and characterization of silver containing chitosan fibersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Yimin Qin Abstract Silver containing chitosan fibers were prepared by blending fine particles of a silver sodium hydrogen zirconium phosphate compound into the spinning solution. It was possible to distribute the silver containing particles in the chitosan fiber because of the high viscosity of the spinning solution and the small diameter of the particles. Because the silver ions are imbedded inside the sodium hydrogen zirconium phosphate complex, the chitosan fibers remain white in color without being oxidized by the silver ions. The release of silver ions from the silver containing chitosan fibers were studied by placing the fibers in contact with distilled water, solution A, and aqueous protein solutions. Results showed that the release of silver ions was low in water, while in solution A and protein solutions, the silver ions are activated through ion exchange and chelation. The silver ions can significantly enhance the antimicrobial properties of the chitosan fibers. Experimental results showed that when placed in contact with the silver containing chitosan fibers, the reduction in bacteria count can be more than 98%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3622,3627, 2007 [source] Electrospun Hybrid Nanofibers Based on Chitosan or N -Carboxyethylchitosan and Silver NanoparticlesMACROMOLECULAR BIOSCIENCE, Issue 9 2009Hristo Penchev Abstract Hybrid nanofibers from chitosan or N -carboxyethylchitosan (CECh) and silver nanoparticles (AgNPs) were prepared by electrospinning using HCOOH as a solvent. AgNPs were synthesized in situ in the spinning solution. HCOOH slowed down the cross-linking of the polysaccharides with GA enabling the reactive electrospinning in the presence of poly(ethylene oxide) (PEO). EDX analyses showed that AgNPs are uniformly dispersed in the nanofibers. Since AgNPs hampered the cross-linking of chitosan and CECh with GA in the hybrid fibers, the imparting of water insolubility to the fibers was achieved at a second stage using GA vapors. The surface of chitosan/PEO/AgNPs nanofibers was enriched in chitosan and 15 wt.-% of the incorporated AgNPs were on the fiber surface as evidenced by XPS. [source] Photocatalytic Deposition of Silver Nanoparticles onto Organic/Inorganic Composite NanofibersMACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2006Sang Kyoo Lim Abstract Summary: In this work, silver nanoparticles were embedded in electrospun organic/inorganic composite nanofibers consisting of PAN and TiO2 through photocatalytic reduction of the silver ions in silver nitrate solutions under UV irradiation. The morphology and diameter of PAN/TiO2 composite nanofibers could be controlled by varying the initial contents of TiO2 in the spinning solution. From TEM images and UV-Vis spectra, it has been confirmed that monodisperse silver nanoparticles with a diameter of ,2 nm were deposited selectively upon the titania of the as prepared composite nanofibers. The amount of Ag nanoparticles embedded on composite nanofibers was greatly influenced by the amount of TiO2 in composite nanofibers, reflecting the role of titania as the inorganic stabilizer and photocatalyst. Morphology of silver nanoparticles embedded on PAN/TiO2 composite nanofibers. [source] Gel-spun polyacrylonitrile fiber from pregelled spinning solutionPOLYMER ENGINEERING & SCIENCE, Issue 7 2010Lianjiang Tan Polyacrylonitrile (PAN) fibers have been gel spun from pregelled PAN spinning solution. The pregelled solution had network structure with elevated spinnability, the as-spun fiber from which had more circular cross-section and reduced skin-core difference. Drawing was more effective in inducing the segmental orientation and crystallization in gel-spun fiber than in dry,wet spun fiber. The mechanical properties of the gel-spun fiber were better than those of the dry,wet spun fiber after multi-stage drawing. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers [source] Preparation of poly(ether sulfone) nanofibers by gas-jet/electrospinningJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008Yi Lin Abstract Poly(ether sulfone) (PES) nanofibers were prepared by the gas-jet/electrospinning of its solutions in N,N -dimethylformamide (DMF). The gas used in this gas-jet/electrospinning process was nitrogen. The morphology of the PES nanofibers was investigated with scanning electron microscopy. The process parameters studied in this work included the concentration of the polymer solution, the applied voltage, the tip,collector distance (TCD), the inner diameter of the needle, and the gas flow rate. It was found from experimental results that the average diameter of the electrospun PES fibers depended strongly on these process parameters. A decrease in the polymer concentration in the spinning solutions resulted in the formation of nanofibers with a smaller diameter. The use of an 18 wt % polymer solution yielded PES nanofibers with an average diameter of about 80 nm. However, a morphology of mixed bead fibers was formed when the concentration of PES in DMF was below 20 wt % during gas-jet/electrospinning. Uniform PES nanofibers with an average diameter of about 200 nm were prepared by this electrospinning with the following optimal process parameters: the concentration of PES in DMF was 25 wt %, the applied voltage was 28.8 kV, the gas flow was 10.0 L/min, the inner diameter of the needle was 0.24 mm, the TCD was 20 cm, and the flow rate was 6.0 mL/h. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008 [source] Thermostability of Lyocell Dopes Modified with Surface-Active AdditivesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 8 2005Frank Wendler Abstract Summary: Cellulose/N -methylmorpholine- N -oxide monohydrate (NMMO) spinning solutions were modified with surface-active additives to yield Lyocell fibers with functional properties. Based on cellulose fibers, a new class of materials with tailored adsorption characteristics are produced. Activated charcoal and carbon black used as additives significantly affect the thermostability of the spinning solutions. Considering the degree of filling three general tendencies become evident. It is most obvious that the onset temperature of dope decomposition is shifted towards lower values accompanied by viscosity reduction after annealing at elevated temperatures and an enhanced formation of degradations products. Morpholine, N -methylmorpholine and formaldehyde as the main degradation products were detected in aqueous distillates by means of HPLC. To study the rate of by-product formation during preparation of the solution kinetic measurements were carried out. Thermal instabilities are not only initiated by heavy metal ions, especially Fe(II), but also by the particle size and porosity of the charcoal. The nano-scaled carbon black used causes autocatalytic reactions as revealed by calorimetric measurements. Relationships between amount of Acc versus onset temperature (Ton) and concentration of N -methylmorpholine. [source] Preparation and characterization of ultrafine electrospun polyacrylonitrile fibers and their subsequent pyrolysis to carbon fibersPOLYMER INTERNATIONAL, Issue 8 2006Juthawan Sutasinpromprae Abstract The present contribution reports the fabrication and characterization of ultrafine polyacrylonitrile (PAN) fibers by electrospinning and further development of the as-spun PAN fibers into ultrafine carbon fibers. The effects of solution conditions (i.e., solution concentration, viscosity, conductivity, and surface tension) and process parameters (i.e., applied electrostatic field strength, emitting electrode polarity, nozzle diameter, and take-up speed of a rotating-drum collector) on morphological appearance and average diameter of the as-spun PAN fibers were investigated by optical scanning (OS) and scanning electron microscopy (SEM). The concentration, and hence the viscosity, of the spinning solutions significantly affected the morphology and diameters of the as-spun PAN fibers. The applied electrostatic field strength and nozzle diameter slightly affected the diameters of the as-spun fibers, while the emitting electrode polarity did not show any influence over the morphology and size of the as-spun fibers. Utilization of the rotating-drum collector enhanced the alignment of the as-spun fibers. Within the investigated concentration range, the average diameter of the fibers ranged between 80 and 725 nm. Finally, heat treatment of the as-spun fibers with their average diameter of about 450 nm was carried out at 230 and 1000 °C, respectively. Various characterization techniques revealed successful conversion into carbon fibers with an average diameter of about 250 nm. Copyright © 2006 Society of Chemical Industry [source] | ||||||||||