Materials Literature
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Fluoromethylene cyanate ester resins derived from the monomer series N⋮CO−CH 2 (CF 2 ) n CH 2 −OC⋮N (where n = 3, 4, 6, 8, and 10) have been synthesized and characterized. Monomer melting points range from −8 to 181 °C, and characterization includes 1 H, 13 C, and 19 F NMR and IR spectroscopy and DSC. Purification is…
The new generation of silicon‐carbide‐based fibres made from organosilicon precursors, cross‐linked by electron irradiation, have been compared with the earlier fibres which have undergone cross‐linking in air. The latest fibres, known as Tyranno Lox‐E and Hi‐Nicalon, possess a lower oxygen content (≈5 wt% and ≈0.5 wt…
The peculiar feature of copper ion-exchanged mordenite in dinitrogen (N 2 ) adsorption has been investigated through the measurements of infrared (IR) and emission spectra (ES) and X-ray absorption fine structure (XAFS). IR spectra provided the definitive evidence for the existence of at least two kinds of adsorption…
A combination of two in situ small-angle scattering techniques are employed to compare the texture and molecular order in flowing LCPs that exhibit constant viscosities (region II) and shear thinning (region I) at low shear rates. The microstructure is characterized by an overall molecular orientation S eff, a texture…
We have measured the V 2p3/2 and O 1s X-ray absorption spectra of singlecrystal V2O5 and compared them with linear-combination-of-atomic-orbitals density-of-states (DOS) calculations. The spectra change dramatically with incident angle and the use of polarized light and a single crystal limits the number of transition…
Investigations have been performed on the La‐modified (1 ‐ x )Pb(Mg 1/3 Nb 2/3 )O 3 —( x )PbTiO 3 crystalline solution for compositions close to the morphotropic phase boundary (MPB) using energy‐dispersive X‐ray spectrometry (EDS). Studies were performed on specimens with La contents between 0 and 10 at.% for x = 0.3…
The present status of the dominant mechanisms of charge-carrier scattering in lead telluride is analyzed critically. It is shown that the role of the Coulomb potential of the vacancies and the role of the deformation potential of acoustic phonons in carrier scattering in PbTe has been strongly overestimated in most ex…
The structure of nanocomposites fabricated using carbon nanotube templates using transmission electron microscopy and electron energy‐loss spectroscopy will be described here. Examples for filled, network substituted and uniformly coated nanotubes will be described. The novelty of such nanocomposite structures and the…
Several molecular devices based on the electronic switching properties of conducting polymers have been described previously and involve an addition/removal of a proton/electron to/from the polymer chain. This “doping” process creates charged topological defects such as polarons or bipolarons, which act as charge carr…
Magic angle spinning at sufficiently high rates dramatically changes the sample temperature. A method is described for calibrating a probe head for the thermal effects encountered during magnic angle spinning experiments. Using Sm2Sn2O7 as a chemical shift thermometer, the overlapping effects of ‘external’ heating or…
Film growth conditions were selected to enable the extent of migration of fluoride ions in anodic oxides on tantalum to be determined precisely. By using a preformed film formed in sodium orthosilicate electrolyte in which the incorporated silicon species are immobile, a marker is generated to which mobilities may be…
Other| February 01, 1997 Montmorillonite under high H2O pressures: Stability of hydrate phases, rehydration hysteresis, and the effect of interlayer cations Tzy-Chung Wu; Tzy-Chung Wu Cornell University, Department of Geological Sciences, Ithaca, NY, United States Search for other works by this author on: GSW Google S…
Average crystallite size and mean‐square strain of illite in rock specimens and clay separates were measured independently in TEM images and by single‐line Fourier (Voigt method) profile analysis of the c . 1 nm peak of XRD patterns for a prograde sequence of pelitic rocks (illite crystallinity indices=0.17–0.58°Δ2 θ…
Abstract A new procedure for the determination of the amounts of phases in samples of isotactic poly(propylene) quenched at different cooling rates from the same melted polymer is described. According to the procedure, all the patterns corresponding to the same quenching series are simultaneously analyzed for the amou…
A new type bistable reflective cholesteric liquid crystal display is reported. The texture and the relaxation process are very different from other types of the reflective cholesteric displays reported previously. The contrast ratio of the display is about 2.5 times higher than regular cholesteric displays. The respon…
Sliding wear properties of ultra‐fine‐grained (180 nm) yttria‐doped tetragonal zirconia (Y‐TZP) ceramics were examined with porosities from 1.5% to 7%. On a pin‐on‐plate tribometer under dry‐N 2 conditions, e.g., wear rates of the material increase by a factor of 5 by increasing porosity with a factor of 5 (from 1.5 t…
Optically reflective and surface-conductive polyimide films have been prepared by the incorporation of silver(I) acetate and trifluoroacetylacetone into a dimethylacetamide solution of the poly(amic acid) formed from 3,3‘,4,4‘-benzophenonetetracarboxylic acid dianhydride (BTDA) and 4,4‘-oxydianiline (4,4‘-ODA). Therma…
Abstract A sol‐gel granulation process was developed to prepare porous nanostructured γ‐alumina granules as supports for catalysts and adsorbents. The process, which starts with an aqueous sol of gelatinous boehmite, involves droplet formation, gelation in paraffin oil, conditioning in ammonia solution, and drying and…
The excitation and radiative recombination mechanisms of carriers in electroluminescent porous silicon (PS) have been studied for the device with the structure of Au/PS/n-type Si. Experiments focus on the electroluminescence (EL) and photoluminescence (PL) spectra, the current-voltage-EL intensity relationship and its…
The birefringence induced by partially ordered polymer networks dispersed in an isotropic phase of liquid crystals is studied. Polymer networks were formed by the polymerization of 1--4 % mixtures of prepolymer in the nematic phase of liquid crystals. The partial nematic (paranematic) ordering is analyzed in terms of…