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Good Mechanical Strength (good + mechanical_strength)
Selected AbstractsElectrochemical preparation of composite polyaniline coating and its application in the determination of bisphenol A, 4- n -nonylphenol, 4- tert -octylphenol using direct solid phase microextraction coupled with high performance liquid chromatographyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 16 2005Minjia Huang Abstract For SPME-HPLC, metal wires with better mechanical strength are preferred over the fused silica fibers. In this article, a novel composite polyaniline (CPANI) doped with PEG and polydimethylsiloxane coating (CPANI fiber) was prepared on a stainless steel wire by a three-electrode system: the fiber was used as the work electrode, a calomel electrode and a platinum electrode were used as the reference and the counter electrodes, respectively. To evaluate the new CPANI coating, the coating was used to extract three kinds of phenols (bisphenol A, 4- n -nonylphenol, and 4- tert -octylphenol) in water samples by direct-SPME mode and then desorbed in commercial SPME-HPLC interface to separation. The extraction procedure was also optimized. Five real water samples were investigated. Good recoveries were gained when environmental samples were analyzed. [source] Synthesis of pH-responsive crosslinked poly[styrene- co -(maleic sodium anhydride)] and cellulose composite hydrogel nanofibers by electrospinningPOLYMER INTERNATIONAL, Issue 5 2009Shengguang Cao Abstract BACKGROUND: Stimuli-sensitive materials show enormous potential in the development of drug delivery systems. But the low response rate of most stimuli-sensitive materials limits their wider application. We propose that electrospinning, a technique for the preparation of ultrafine fibrous materials with ultrafine diameters, may be used to prepare materials with a fast response to stimuli. RESULTS: Poly[styrene- co -(maleic sodium anhydride)] and cellulose (SMA-Na/cellulose) hydrogel nanofibers were prepared through hydrolysis of precursor electrospun poly[styrene- co -(maleic anhydride)]/cellulose acetate (SMA/CA) nanofibers. In the presence of diethylene glycol, the SMA/CA composite nanofibers were crosslinked by esterification at 145 °C, and then hydrolyzed to yield crosslinked SMA-Na/cellulose hydrogel nanofibers. These nanofibers showed better mechanical strengths and were pH responsive. Their water swelling ratio showed a characteristic two-step increase at pH = 5.0 and 8.2, with the water swelling ratio reaching a maximum of 27.6 g g,1 at pH = 9.1. CONCLUSION: The crosslinked SMA-Na hydrogel nanofibers supported on cellulose showed improved dimensional stability upon immersion in aqueous solutions. They were pH responsive. This new type of hydrogel nanofiber is a potential material for biomedical applications. Copyright © 2009 Society of Chemical Industry [source] Polymer Electrolyte Membranes with a Pore-Filling Structure for a Direct Methanol Fuel Cell,ADVANCED MATERIALS, Issue 14 2003T. Yamaguchi Pore-filling membranes that are composed of a porous substrate and a filling polymer electrolyte have been developed. These polyelectrolyte membranes demonstrate low permeation with respect to methanol, high proton conductivity, good mechanical strength, chemical stability, and low cost, making them ideal for use in direct methanol fuel cells. The necessary characteristics can also be controlled by changing the substrate and the filling polymer electrolyte. [source] Synthesis of networked polymers with lithium counter cations from a difunctional epoxide containing poly(ethylene glycol) and an epoxide monomer carrying a lithium sulfonate salt moietyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2010Kozo Matsumoto Abstract Poly(ethylene glycol)-based networked polymers that had lithium sulfonate salt structures on the network were prepared by heating a mixture of poly(ethylene glycol) diglycidyl ether (PEGGE), poly(ethylene glycol) bis(3-aminopropyl) terminated (PEGBA), and an ionic epoxy monomer, lithium 3-glycidyloxypropanesulfonate (LiGPS). Flexible self-standing networked polymer films showed high thermal stability, low crystallinity, low glass transition temperature, and good mechanical strength. The materials were ion conductive at room temperature even under a dry condition, although the ionic conductivity was rather low (10,6 to 10,5 S/m). The ionic conductivity increased with the increase in temperature to above 1 × 10,4 S/m at 90 °C. The film samples became swollen by immersing in propylene carbonate (PC) or PC solution of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The samples swollen in PC showed higher ionic conductivity (ca.1 × 10,3 S/m at room temperature), and the samples swollen in LiTFSI/PC showed much higher ionic conductivity (nearly 1 S/m at room temperature). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3113,3118, 2010 [source] Characterisation of carbonaceous materials using Raman spectroscopy: a comparison of carbon nanotube filters, single- and multi-walled nanotubes, graphitised porous carbon and graphiteJOURNAL OF RAMAN SPECTROSCOPY, Issue 3 2009H. M. Heise Abstract Multi-walled carbon nanotube (MWCNT) filters have been recently synthesised which have specific molecular filtering capabilities and good mechanical strength. Optical and scanning electron microscopy (SEM) reveals the formation of highly aligned arrays of bundles of carbon nanotubes having lengths up to 500 µm. The Raman spectra of this material along with four other carbonaceous materials, commercially available single-walled carbon nanotubes (SWCNTs) and MWCNTs, graphitised porous carbon (Carbotrap) and graphite have been recorded using two-excitation wavelengths, 532 and 785 nm, and analysed for band positions and shape with special emphasis paid to the D-, G- and G,-bands. A major difference between the different MWCNT varieties analysed is that G-bands in the MWCNT filters exhibit almost no dispersion, whereas the other MWCNTs show a noticeable dispersive behaviour with a change in the excitation wavelength. Spectral features similar to those of the MWCNT filter varieties were observed for the Carbotrap material. From the line shape analysis, the intensity ratio, ID/IG, of the more ordered MWCNT filter material using the integral G-band turns out to be two times lower than that of the less ordered MWCNT filter product at both excitation wavelengths. This parameter can, therefore, be used as a measure of the degree of MWCNT alignment in filter varieties, which is well supported also by our SEM study. Copyright © 2008 John Wiley & Sons, Ltd. [source] | |||||||||||||