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Linda Härdelin Johannes Thunberg Erik Perzon Gunnar Westman Pernilla Walkenström Paul Gatenholm 《应用聚合物科学杂志》2012,125(3):1901-1909
Cellulose was electrospun with various concentrations of ionic liquid and cosolvent. Three different cosolvents were used in this study; dimethylacetamide (DMAc), dimethyl formamide (DMF), and dimethyl sulfoxide (DMSO). The cosolvents were added to modify the viscosity, electrical conductivity, and surface tension of the solutions. The solubility of cellulose in ionic liquids is highly affected by changes in solvent properties on the molecular level in the binary solvent systems. The difference in molecular structure of the cosolvents and the interactions between cosolvent and ionic liquid can explain the difference in dissolution power of the cosolvents. Scanning electron microscope (SEM) was used to characterize electrospun cellulose fibers. For the systems tested the importance of having a rather high viscosity and high surface tension, and some degree of shear thinning to produce fibers is shown. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
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Antonios N. Papadopoulos 《Holz als Roh- und Werkstoff》2012,70(1-3):397-397
Acetylated OSB stakes were tested in ground contact in Western Greece. Two levels of acetylation were used, a high and a low level of 20.4% and 11.2% acetyl content, respectively. The highly acetylated stakes showed severe attack after 96 months and total decay after 102 months of testing. 相似文献
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The inhibition effect of two pyrazine derivatives of 2-aminopyrazine (AP) and 2-amino-5-bromopyrazine (ABP) on the corrosion of cold rolled steel (CRS) in 1.0 M hydrochloric acid (HCl) was studied by weight loss, potentiodynamic polarization curves, and electrochemical impedance spectroscopy (EIS) methods. The results show that both AP and ABP are good inhibitors, and inhibition efficiency follows the order: ABP > AP. The adsorption of each inhibitor on CRS surface obeys Langmuir adsorption isotherm. Potentiodynamic polarization curves show that two pyrazine derivatives act as mixed-type inhibitors. EIS spectra exhibit one capacitive loop and confirm the inhibitive ability. 相似文献
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The stabilizing effect of a natural filler, sulfur‐free lignin, on the thermal degradation of natural rubber (NR) was examined. Lignin was incorporated into NR in amounts of 10–30 phr (parts per hundred parts of rubber). It was shown that the lignin preparation used improved the physicomechanical properties of the rubber vulcanizates. Thermogravimetric analysis and differential scanning calorimetry were used to study the thermal degradation of unfilled and lignin‐filled vulcanized natural rubber. Measurements were carried out under atmospheric conditions. It was revealed that lignin used as filler increased the resistance of NR vulcanizates to thermooxidative degradation in air. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1226–1231, 2007 相似文献
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《Synthetic Metals》2004,144(2):133-142
Surface-enhanced Raman scattering (SERS) and cyclic voltammetry (CV) were used to investigate oxidation–reduction processes of single-wall carbon nanotube (SWNT) films deposited on Au supports in 0.5 M H2SO4 solutions. In the potential range (0; +1000) and (0; +1500) mV versus saturated calomel electrode (SCE), the oxidation–reduction reactions of SWNT films are quasi-reversible and irreversible, respectively. Anodic polarization of SWNT films until +1000 mV versus SCE produced compounds similar to the bisulfate intercalated graphite. Regardless of excitation wavelength, i.e. 1064 or 676.4 nm, variation in the Raman spectra exhibited a decrease in the intensity of the bands associated with the radial breathing mode (RBM) situated in the 120–240 cm−1 spectral range. Also an increase in the intensity of the D band is accompanied an up-shift of this band. A gradual decrease of the Breit–Wigner–Fano component was observed at λexc=676.4 nm. Partial restoration of the Raman spectra was achieved by a subsequent alkaline solution treatment. Potentials higher than +1000 mV versus SCE resulted in SWNTs breakage and fragments of different length were formed such as closed-shell fullerene. This was observed in the SERS spectrum by: (i) the disappearance of the RBM band, (ii) the increased D-band shifted to ca. 1330 cm−1 and (iii) the appearance of a new band at 1494 cm−1, frequently observed also in the Raman spectrum of fullerenes on the type C70, C84, C119, as well as in its derivative compounds (e.g. C60O, clathrates, etc.). Appearance and increase in the intensity of the Raman band at 1494 cm−1 as result of an anodic polarization of the SWNT film in solution of H2SO4 0.5 M in 1-butanol is a further evidence of the nanotubes breakage. 相似文献
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