Materials Literature
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ZrO 2 /Al 2 O 3 composites with from 0% to 100% Al 2 O 3 content were diffusion bonded at 12.5 MPa for 30 min in the temperature range 1450° to 1500°C. Under appropriate bonding conditions, a bonding strength greater than 1000 MPa was achievable between dissimilar materials with different thermal expansion coefficient…
Abstract The aim of this study is the synthesis and characterization of polymer composites in which microscopic metal or metal oxide particles are incorporated by thermal or photolytic decomposition in solid solutions of organometallic complexes in polymers. In contrast to conventional composites or filled polymer com…
Abstract Experimental support was obtained for a quantitative ion‐exchange model based on the principle of hard and soft acids and bases (HSAB) applied to monovalent cation exchange on clay minerals, oxides, and exchange resins. According to the model, the thermodynamic exchange constant ( K ex ) can be obtained from…
Organically modified ceramics (ORMOCERs) have been prepared with respect to optical applications. The investigations show that materials can be synthesized with interesting properties for a variety of potential applications. They can be used as hard coatings for the protection of optical polymers, e.g. CR 39 or fluore…
Abstract Polyphosphate esters were synthesized from phenolphthalein and aryl phosphorodichloridates by interfacial polycondensation using a phase transfer catalyst. The polymers were characterized by IR, 1 H‐, 13 C‐, and 31 P‐NMR spectroscopy. The molecular weights were calculated by end group analysis using 31 P‐NMR…
Abstract The structure of an interface that develops from laminating polypropylene/polyethylene (PP/PE) by hot compression‐molding was analyzed by optical and electron microscopy. The interface strength was measured by means of a butt‐joint specimen. For the laminate formed by isothermal crystallization above the PE m…
Abstract A series of fluorine‐containing homopolycarbonate and copolycarbonates with a wide range of unit ratio were synthesized by the two‐phase phase‐transfer‐catalyzed plycondensation of 2,2‐bis (4‐hydroxyphenyl)‐1,1,1,3,3,3‐hexafluoropropane (Bisphenol AF) and/or 2,2‐bis (4‐hydroxy‐phenyl) propane (Bisphenol A) wi…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructural and spectral consequences of ion pairing. 4. Theoretical study of alkali metal tetrafluoroborates (M+BF4-; M = lithium, sodium, potassium, and rubidium)Joseph S. Francisco and Ian H. WilliamsCite this: J. Phys. Chem. 1990, 94, 23, 8522–8529Publication Date (Print)…
The effect of molecular structural changes on the mesomorphic nature of a new class of macrocyclic columnar liquid crystal is reported. Twenty-six new compounds with general molecular structure I were prepared, characterized and compared. Only dodecasubstituted ester derivatives 2d-h exhibit thermotropic mesophases. T…
ABSTRACT Two red wines, from the same cultivar, differing by polysaccharide content were filtered using cross‐flow microfiltration with an alumina membrane, pore size 0.2 μm. Filtration flow rates were different. The wine richest in polysaccharides (A) showed a typical external fouling profile with progressive stabili…
We present measurements of the oxidation level (Cu+ and Cu2+ concentration) of copper thin films deposited using a new type of oxygen plasma source. This oxygen plasma source is operated under ultrahigh vacuum, and allows one to oxidize copper up to nearly pure Cu2+ oxide at rather low temperature (<500 °C) and…
La variete quartz du AlPO 4 cristallise dans P3 1 21 avec a=4,941 et c=10,940 A dans des conditions normales et a=4,605 et c=10,558 A a une pression de 8,51 GPa. L'augmentation de la presion entraine l'augmentation du rapport c/a et la diminution des angles (Al-O-P). Le changement du mode d'empilement de l'oxygene ind…
It has become evident that the float zone crystal growth method and isothermal liquid bridges may be very sensitive to the residual acceleration environment of a spacelab. Indeed, the shape equilibria show a high degree of sensitivity and, thus, even the small steady acceleration associated with the effective low grav…
Abstract Some reactions for the synthesis of poly(phenylenevinylene), PPV, are examined for their capability to form poly(9,10‐anthrylenevinylene). The reasons for the failure of these reactions are described. Soluble oligomers with up to seven anthracene units are synthesized. The properties of the oligomers are stud…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis of 2-(alkanoyloxy)-5-alkoxytropones. Novel monocyclic rod-type liquid crystalsAkira Mori, Hitoshi Takeshita, Katsuhiko Kida, and Minoru UchidaCite this: J. Am. Chem. Soc. 1990, 112, 23, 8635–8636Publication Date (Print):November 1, 1990Publication History Published…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotoluminescence-based correlation of semiconductor electric field thickness with adsorbate Hammett substituent constants. Adsorption of aniline derivatives onto cadmium selenideCatherine J. Murphy, George C. Lisensky, Larry K. Leung, Glen R. Kowach, and Arthur B. EllisCite…
Thermal analysis was performed on coprecipitated materials and on individual components. The detailed decomposition schemes of coprecipitates and individual components are proposed and discussed. According to the proposed decomposition schemes, the values of the observed weight loss are in good agreement with those of…
The composition and structure of boron nitride films prepared by thermal and plasma enhanced chemical vapor deposition (CVD) using borazine as a precursor have been studied. Thermal CVD at temperatures between 475 and 550 °C using either a hot-wall or cold-wall reactor results in amorphous boron-rich films of approxim…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA novel synthetic route to scandium porphyrin derivatives and the first structurally characterized metalloporphyrin-.eta.5-cyclopentadienyl sandwich compoundJohn Arnold and Caroline G. HoffmanCite this: J. Am. Chem. Soc. 1990, 112, 23, 8620–8621Publication Date (Print):Novem…
The implications of a self-consistent mode-coupling theory of dense fluids for the liquid-glass transition are considered. First, we show that when higher-order corrections are ignored from our model, there is a dynamic transition of the hard-sphere fluid at an intermediate density to an ideal glassy phase. This is in…