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  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 55-57 (Aug. 2008), p. 625-628 
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Electrospun fabrics, prepared from 5, 7 and 10%w/v were Poly(vinyl alcohol) (PVA) solutions successfully prepared. The electrospinning condition was 15 kV, distance 15 cm, flow rate of 1 ml/hr and spinning time of 5 hours. Physical properties of electrospun PVA fabrics were analysed by SEM, FE-SEM and contact angle measurement.The contact angle of the electrospun PVA fabrics was 54.5°, characterizing the hydrophilicity of the fabrics. Hydrophobic properties of the electrospun PVA fabrics were improved by plasma treatment using radio frequency inductively coupled plasma (RF-ICP). RF-ICP plasma treatment of the electrospun PVA fabrics were carried out sulphurhexafluorene (SF6) gas with pressure of 0.5 Torr, RF power of 30W and treating time of 30, 60, 90 and 120 seconds. Effects of the PVA solution concentration and plasma treating time on hydrophobicity of the electrospun PVA fabrics were determined by contact angle that result of contact angle of treated fabrics increased when treated time increased and they decreased when concentration of fabrics increased
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 55-57 (Aug. 2008), p. 733-736 
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Electrospinning has been recognized as an efficient technique for the forming of polymer nanofibers. In this project interest fabricated Soy Protein Isolate (SPI) nanofibers by electrospinning with different supply voltages, positive and negative charge. SPI was dissolved in 80%-95% w/w acetic acid solution and 80%-90% w/w formic acid solution. Only droplet formation of SPI were found instead of fibril formation, and the droplet morphology of SPI is depended on supply voltage, and type of solvent. SPI droplets from the negative supply voltage have smaller and more nodular than droplets from positive supply voltage. Formic acid SPI solution gives smaller size of droplet and more nodular than acetic acid SPI solution. In order to forming SPI nanofibers, zein/SPI blend were performed. The zein/SPI blend was studied at difference blending ratio. The 95/5 Zein/SPI was found to be the best blend composition for electrospun fiber. In addition, the effects of electrostatic distance and electrostatic voltage on electrospun fiber were also investigated. Increasing electrostatic distance or increasing voltage, smaller size of fiber was obtained
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Advances in science and technology Vol. 54 (Sept. 2008), p. 243-248 
    ISSN: 1662-0356
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Natural Sciences in General , Technology
    Notes: Blends of poly(trimethylene terephthalate) (PTT) and poly(buthylene terephthalate)(PBT) in the amorphous state were miscible in all of the blend compositioins studied, as evidencedby a single, composition-dependent glass-transition temperature observed for each blendcomposition. The variation in the glass-transition temperature was well-predicted by the Gordon-Taylor equation, with the fitting parameter being 1.37. The cold-crystallization (peak) temperatureincreased with increasing PBT content in the blends. The subsequent melting endotherms after meltcrystallization exhibited melting point depression behavior in which the observed meltingtemperatures decreased with an increasing amount of minor component of the blends. LHW andNLHW were used to determine the equilibrium melting temperature of the blends. The values ofthe overall crystallization rate parameters for these blends were all found to increase withdecreasing crystallization temperature, suggesting that these blends crystallized at low temperaturesfaster than that at high temperatures. As the content of PBT was further increased, these valuesdramatically decreased. This result is similar to that observed in the growth rate. From LHsecondary nucleation theory, PTT ,PBT and their blends showed the transition temperaturesbetween regime III and II about 194oC. Banded spherulites were observed for PTT/PBT blends.The spacing of bands of PTT increases with increasing Tc. The body of spherulite texture is moreopen with increasing PBT content. In addition, the boundary of spherulite is also changed withcomposition
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 55-57 (Aug. 2008), p. 153-156 
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Lithium niobate powder (LiNbO3) were synthesized by citrate gel method using LiNO3, Nb2O5, citric acid and HF as starting materials. LiNO3 was dissolved in distilled water that activated into LiOH. Nb2O5 was dissolved in minimum amount of HF at 370C for 20 h. that activated into NbF5. Then citric acid, LiOH, and NbF5 were mixed in stoichiometric ratio. On heating at 1000C for 3-4 h. a yellowish gel is formed. Lithium niobate powders were obtained after calcination at 550-7000C. The effect of calcination temperature at various temperatures ranging from 5500C to 7000C were investigated. The phase and chemical composition of the synthesized powders were characterized by using XRD, SEM, TEM, FTIR and EDX. We found that the lithium niobate crystallize phase formed when the calcination temperature at 6500C with average particle size of around 100 nm
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Titanium dioxide nanofibers were fabricated by electrospinning technique. The titaniasolutions were obtained from adding various types of Ti precursor (Ti(OBu)4, Ti(OiPr)4, andTi(OPr)4) to an ethanol solution containing polyvinyl pyrrolidone (PVP). Acetic acid was used tostabilize the solution and to control the hydrolysis reaction. The porous and well-defined crystallinestructure was obtained after calcined at 450oC for 1 h. The thermal behavior, phase compositionincluding crystallite size, as well as the morphology of as-synthesized nanofibers was obtained fromthermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM)and transmission electron microscopy (TEM), respectively. The average diameter of these nanofiberswas in the range from 100 to 400 nm depending on titania precursor. The photocatalytic activity ofTiO2 fibers were evaluated for NOx degradation in a gaseous phase. The results demonstrated that atthe same catalyst loading, the photocatalytic activity of TiO2 nanofiber was higher than thecommercial Degussa P-25
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 681-692 
    ISSN: 0887-6266
    Keywords: high-density polyethylene ; nonisothermal crystallization kinetics ; plateau temperature ; regime transition ; crystallinity ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The quiescent nonisothermal bulk crystallization kinetics of two high-density polyethylene resins were investigated by a modified light-depolarizing microscopy (LDM) technique. The technique allows studies at average cooling rates up to 2500°C/min. The polymer was found to crystallize at a pseudo-isothermal temperature even at these very high cooling rates. The overall bulk crystallization rate increased rapidly as the cooling rate and supercooling increased. Crystallization kinetics was analyzed by Avrami analysis. Avrami exponents near 3 suggested spherical growth geometry and instantaneous nucleation at predetermined sites. Observation of spherulites by optical microscopy together with a number density of spherulites that changed little with increase in cooling rate or supercooling supported this model of crystallization behavior. Analysis of the half-time of crystallization based on the Lauritzen and Hoffman secondary nucleation theory indicated that the regime II-III transition was found to occur at a degree of supercooling of approximately 22°C. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 681-692, 1998
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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