Materials Literature
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The sintering of ultrafine γ‐Al 2 O 3 powder (particle size ∼10–20 nm) prepared by an inert gas condensation technique was investigated in air at a constant heating rate of 10°C/min. Qualitatively, the kinetics followed those of transition aluminas prepared by other methods. Measurable shrinkage commenced at ∼ 1000°C…
Abstract 13 C NMR analysis of the chain‐end distribution of poly(propylenes) prepared using the highly active catalyst system MgCl 2 /TiCl 4 /diether—AlEt 3 has revealed particularly high proportions of butyl chain‐ends in polymers prepared at relatively low hydrogen pressures. This indicates that the high sensitivity…
We have performed a molecular-dynamics simulation for a sample of amorphous ${\mathrm{SiO}}_{2}$ subject to a compression-decompression process at ambient temperature, using a recently proposed two-body potential model. For moderate compression the simulated glass maintains the ideal tetrahedral coordination and displ…
Abstract Enzymatic ring‐opening polymerization of a 16‐membered lactone, 15‐pentadecanolide (PDL), has been carried out in bulk using various lipases of different origin as catalyst. The polymerization with Pseudomonas fluorescens lipase (lipase PF) catalyst afforded the corresponding polyester in high yields. The rat…
During sample preparation, the coarse fraction (> 2 mm) of soils is commonly excluded from further analytical determinations. Our results demonstrated, however, that the coarse fragments of soils derived from sandstone in Tuscany, Italy, are not chemically inert. From an intensive study of the clasts from three profil…
We calculate the free energy of a model for a polymer melt in a computer simulation of the bond-fluctuation model and determine the entropy of the melt over a wide range of temperatures, including the region close to the glass transition. The results are compared with the Gibbs-DiMarzio theory, a theory by Flory for s…
Thick films of lead zirconate titanate of the morphotropic phase boundary composition, Pb(Zr 0.52 Ti 0.48 )O 3 , have been fabricated on platinum‐buffered silicon using a modified sol–gel spin‐coating technique. Crack‐free films of 12‐μm thickness can be uniformly deposited on 3‐in.‐diameter wafers with high yield and…
Recently, it has been argued that a strong electron-phonon interaction arising from the Jahn-Teller splitting of the outer Mn $d$ level plays a crucial role in understanding the nonmetal-to-metal transition observed in the ${\mathrm{La}}_{1\ensuremath{-}x}{A}_{x}\mathrm{Mn}{\mathrm{O}}_{3}(A=\mathrm{C}\mathrm{a},\phan…
Crosslinking behavior of internal acetylene units linked para to the aromatic rings was investigated by preparing polyimide from 4,4′-diaminodiphenylacetylene (p-intA) and 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA). Polyimide was also prepared from 1,4-phenylenediamine (PDA) and 6FDA for compari…
The glass transition, onset crystallization, solidus, and liquidus temperatures of a ZBLAN glass have been measured by differential thermal analysis in a sealed Pt ampoule. The onset crystallization was observed at 335°C for a powdered glass, while for a monolithic glass, prepared by in situ quenching in the Pt capsul…
UV-curable transparent epoxy adhesives have been specifically developed for the fabrication of optical communictions precision devices. The newly developed adhesives using cylohexane type fluoro-epoxy as the base resin and speherical quartz filler have extremely low volume shrinkage of 1.2% during curing and the cured…
In order to evaluate the thermal conductivity of oxidized fuel pellets of leaker fuel rods, UO2+x samples with x between 0.00 and 0.20 were prepared by an oxidation or a sintering method. Sample thermal diffusivities were measured by using a laser flash method from 300 to 1,400 K and their thermal conductivities were…
An alternating copolymer of N-methylmaleimide and isobutene was produced by a radical precipitation polymerization method. The copolymer thus produced is a new class of transparent polymeric material that shows a unique balance of optical, thermal, and mechanical properties. The visible light transmittance was more th…
High‐purity alumina powder with submicrometer particle size was colloidally dispersed and classified in either water or ethanol to remove agglomerates from as‐received powder. After the slurries were dried, fine alumina particles cohered to form agglomerates, which were “hard” when formed in a water slurry, and “soft”…
Cathodic and anodic behaviour of aluminium has been investigated in AlCl3DMSO2—dimethylsulfone—(1 mole/kg) electrolyte at 130 °C by current reversal chronopotentiometry (CRC) and chronoamperometry. Al deposition study showed that a diffusion-limited current density close to 83 mA cm−2 is reached for potentials less th…
Abstract Polyurethane elastomers were investigated as electrically active materials for actuators. Components in hard segment and soft segment in the elastomers were varied. The elastomers with excellent electrostrictive properties were limited to those which had soft segments of polyesters and polylactones. It turned…
Other| August 01, 1996 Heat capacity and thermodynamic properties of nearly stoichiometric wustite from 13 to 450 K Svein Stolen; Svein Stolen University of Oslo, Department of Chemistry, Oslo, Norway Search for other works by this author on: GSW Google Scholar Ronny Glockner; Ronny Glockner Search for other works by…
The chemical structure of sodium aluminosilicate glasses is determined by high resolution x-ray photoelectron spectroscopy (XPS) as silicon is gradually replaced by aluminum. A well-defined chemical state is found for silicon, aluminum, and sodium atoms, while three different environments are identified for oxygen ato…
Abstract The changes in amount and location of layer charge during diagenetic alteration have been investigated for smectites and smectite layers of illite/smectite interstratified minerals (I/S) by X-ray powder diffraction analysis with various expansion behavior tests: 1) ethylene glycol (EG) solvation (XRD); 2) K-s…
The electrochemical corrosion potential (ECP) of stainless steel (SS) was measured under simulated boiling-water reactor (BWR) coolant circuit conditions using a rotating cylinder electrode (RCE). Based upon those measurements, an empirical model was developed to predict ECP of structure materials in a BWR primary cir…