Materials Literature
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Based upon the similarities in properties between carbon- and BN-based (BN=boron nitride) materials, we propose that BN-based nanotubes can be stable and study their electronic structure. A simple Slater-Koster tight-binding scheme has been applied. All the BN nanotubes are found to be semiconducting materials. The ba…
Abstract Glycidol has been introduced into isocyanate‐terminated polyurethane to form glycidyl‐terminated polyurethane resin. A series of glycidyl‐terminated polyurethanes, based on PTMEG, PPG, and polyester soft segments, having different molecular weights were synthesized and their adhesion properties on aluminum we…
Abstract The present investigation pertains to the structure–property relationships of highly structured graft copolymers. The specific model graft copolymers are based on an elastomeric backbone, i.e., poly(ethyl acrylate), and monodisperse thermoplastic grafts, i.e., polystyrene. The synthesis of these graft copolym…
Abstract This article reports on the synergistic effects observed during the processing of cellulose with bacteria‐produced polyhydroxybutyrate (PHB). Cellulose fibers processed with PHB‐melt exhibited defibrillation as shown by SEM. Microscopic studies of extracted fibers demonstrated that a dramatic fiber‐size reduc…
We have performed neutron spin-echo measurements on the supercooled glass-forming system 7 LiCl,6D 2 O above its glass transition temperature (T g =135 K). This investigation has permitted us to determine the time dependence of the density correlation function phi (Q, t) between 2 ps and 2 ns at the maximum of the str…
Well-ordered graphite thin films were obtained by chemical vapor deposition of 2-methyl- 1,2′-naphthyl ketone on Ni substrates at substrate temperatures higher than 600 °C. Values of interlayer spacing calculated from x-ray diffraction data were between 3.360 and 3.350 Å. Raman scattering spectra of the films showed a…
Abstract Highly transparent and conducting polypyrrole–(PPy–N) and polyaniline–nylon 6 (PAN) composite films could be easily obtained by immersing nylon 6 films containing pyrrole or aniline into an oxidant solution such as aqueous FeCl 3 solution or aqueous (NH 4 ) 2 S 2 O 8 solution containing HCl. The conductivity,…
Abstract The effect of interaction between carbon black and polymer on electrical behavior was studied using the ESR method. The polymer matrices used were HDPE, LDPE, and ethylene/vinyl acetate (EVA). Two kinds of carbon blacks (CB), high structure CSF‐III and low structure FEF, were used as a conductive filler. Comp…
The low frequency dielectric response of relaxor ferroelectrics is analyzed. Following the conventional approach this response is considered as a sum of those of relaxators having an exponentially wide and smooth spectrum of the relaxation times. It is shown that the Vogel-Fulcher relationship for the positions of the…
Electronic structure investigations on a broad range of gold compounds, including naked and ligated gold clusters, are reviewed. The calculations have been carried out with a recently introduced relativistic variant of the linear combination of Gaussian-type orbitals density-functional (LCGTO–DF) method which affords…
Long, nanometer-size metallic wires can be synthesized by injection of the conducting melt into nanochannel insulating plates. Large-area arrays of parallel wires 200 nanometers in diameter and 50 micrometers long with a packing density of 5 x 10(8) per square centimeter have been fabricated in this way. When charged,…
The phase transition from an isotropic to a nematic phase for a classical fluid of hard ellipsoids has been studied using a version of a theory originally due to Onsager and by computer simulation. In the proposed form of the Onsager theory for the Helmholtz free energy, both the second and the third virial coefficien…
Abstract NMR, potentiometric, and UV/VIS measurements were run to study the protonation and the In 3+ and Cu 2+ stability constants of 1,4,7,10‐tetraazacyclododecane‐1,4,7‐triacetic acid (do3a, L). The protonation of do3a follows the typical scheme with two high and several low log K H values. Between pH 11 and 13, th…
Abstract The present study deals with the investigation of the desorption of vinyl chloride from various commercial and experimental suspension PVC resins in a laboratory fluidized bed drier simulating an industrial drier. The results show that PVC resins may differ widely in the rate at which the monomer is desorbed.…
Abstract A potential mechanism for part of the production decline observed in the Prudhoe Bay field is siderite (iron carbonate) scale deposition. This laboratory investigation focused on evaluating the effect of the existing downhole scale inhibitor program on the proposed siderite formation damage mechanism. A tube…
Abstract Scale inhibitor "squeeze" treatments are used extensively to control problems with downhole carbonate and sulphate scale formation. The return curve from an adsorption/desorption squeeze is governed by the inhibitor/rock interaction which, in turn, is described by the adsorption isotherm. Several factors, suc…
Bundles of nanotubes were produced by vapor-phase condensation of carbon on highly oriented pyrolytic graphite and analyzed by scanning tunneling microscopy. The bundles are found to have widths between 15 and 50 nm, and up to 200 nm long. They are composed of concentric tubules with 2–4 nm in diameter. Atomic resolut…
We compute phase diagrams for diblock copolymers in the strong-segregation regime as a function of volume fraction \ensuremath{\varphi}. We include the ordered bicontinuous double-diamond (OBDD) phase, which is found to be stable between cylinders and lamellae, consistent with experiment, for \ensuremath{\varphi} (or…
First-order Raman scattering of A 1g and E g modes originating from the antiferrodistortive F 2u soft mode confirms the cubic-tetragonal (O h -D 4h ) phase transition in Sr 0.993 Ca 0.007 TiO 3 , at T 0 =125 K. Within the cubic and the tetragonal phase first-order Raman scattering of the soft ferroelectric F 1u mode (…
Abstract Thermal degradation of polyurethane samples was studied by a thermogravimetric method. The effect of soft‐segment length and soft‐segment concentration on activation energy of the degradation process was measured. Three methods of calculation gave activation energies at different stages of the very complex we…