Materials Literature
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The overall performance of pentane blown rigid polyurethane foams in terms of insulation value and mechanical properties is demonstrated. The low vapor pressure of both normal-pentane and cyclopentane is shown to induce condensation effects. The consequences of condensation in terms of thermal conductivity and dimensi…
Abstract The Ramberg-Osgood strain-hardening exponents and coefficients are characterized for an unirradiated ASTM A302-B steel over a wide range of temperatures from −129 to 260°C. The strain-hardening exponent increases only slightly with temperature over this range, while the coefficient decreases with increasing t…
Abstract Several poly(acrylonitrile)‐g.co‐hydroxyethyl methacrylate graft copolymers were prepared using gamma irradiation ( 60 Co). The influences of the monomer concentration and the time of irradiation on the level of grafting were studied. Some of the graft copolymers obtained were characterised and used for the c…
The influence of chromium on homogeneity of gels and on mullite formation at 980°C was examined by DTA coupled with quadrupole mass spectrometry (QMS), X‐ray diffraction (XRD), and SEM, EDX, and TEM analyses. Mullite precursors were prepared according to the method which provides completelyhomogeneous gels in the Al 2…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMetalloporphyrins with X[N2O2]- Ligands. Novel High-Spin (N-Phenyl-N-nitrosohydroxylaminato)(meso-tetraarylporphyrinato)iron(III)Geun-Bae Yi, Masood A. Khan, and George B. Richter-AddoCite this: Inorg. Chem. 1995, 34, 23, 5703–5704Publication Date (Print):November 1, 1995Pub…
We consider the system of a network formed by crosslinking a polymer blend. In such a system there is a competition between monomer-monomer interactions and elastic energy which may result in a microphase separation. We first treat the problem by adapting a model due to de Gennes to include the effect of concentration…
Young's moduli, creep properties, and time to failure under steady loads were measured for two types of alumina‐based single fibers. Microstructural changes during deformation (grain growth and cavitation) have been analyzed. Experimental dispersion has been correlated to fiber diameter scatter. It has been shown that…
Two types of smectic A and smectic C phases, respectively, have been proved by X-ray and DSC methods for compounds that are terminal non-polar, but consist of tuning-fork shaped molecules. The structural models of the phases are discussed on the basis of steric interaction and of a dense packing. The X-ray patterns of…
This paper presents a dynamic equivalent circuit model of solid magnetic cores for high frequency operations in power electronic circuits. The effects of eddy current, domain wall motion, and hysteresis are taken into account by distributed equivalent resistors and distributed nonideal differential inductors, respecti…
Two different solutions to the problem of simply supported conical shells under axial compression suggested by previous investigators are extensively compared and the problems associated with each type of solution are identified. In terms of buckling load, both solutions are in good agreement but significant differenc…
The thermal conductivity, heat capacity and heat generation properties of two poled piezoceramic materials, a "soft" PZT-5H and a "hard" PZT-4S, were measured over the temperature range from 20 K to above 150 K. A single sample was used for each test type. The thermal conductivity (in the poling direction) of PZT-5H i…
Shock wave processing of Ti-SiC powders has been numerically analyzed at the particle level using an Eulerian finite-element methodology. The analysis reveals that the shock consolidation is dominated by the viscoplastic deformation of Ti particles and that inertia plays a significant role in setting the magnitude of…
Abstract A torque rheometer method has been developed to evaluate the melt behavior of biopolyesters. The main features of this technique include: (i) a modified equipment configuration, so as to maintain the melt temperature within ± 1°C pf the set temperature after the first few minutes of polymer melting and therma…
The structural and electronic properties of the zinc-blende, beta -Sn and rock-salt phases of BP are calculated within the local-density approximation. Two competing methods-LMTO and the pseudopotential plane-wave method-have been used. The agreement between the two electronic structure methods is excellent. We obtain…
Abstract Generation of the molecular electrostatic potential (MEP) profiles, in color‐coded form, on the solvent‐accessible contact surfaces of the two main conformations that sucrose adopts in vacuo as well as in aprotic solvents (e.g. DMF), clearly shows the secondary glucosyl‐2‐OH to be the most electropositive of…
The six-dimensional framework developed by Stroh to treat the elasticity theory of dislocations in crystals has been extended to a twelve-dimensional formalism in quasicrystals. The elastic fields induced by a straight dislocation line in quasicrystals are given in terms of integral representations, which may be suita…
The microfocus X-ray beamline at the European Synchrotron Radiation Facility has been used to investigate the variation in molecular orientation and crystallinity in spherulites of the organic polymer poly-3-hydroxybutyrate (PHB). This is the first report of the correlation of optical and X-ray measurements on spherul…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPoly(ureidosilazanes): Preceramic Polymeric Precursors for Silicon Carbonitride and Silicon Nitride. Synthesis, Characterization, and Pyrolytic Conversion to Si3N4/SiC CeramicsDietmar Seyferth, Carsten Strohmann, Neal R. Dando, and Anthony J. PerrottaCite this: Chem. Mater.…
An iterative algorithm has been developed that takes starting values derived by an envelope method but then minimizes the influence of the envelopes and emphasizes the actual measured data. This combination avoids the difficulties inherent in the accurate drawing of the envelopes and makes it possible to extract the t…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis of Colloidal Polypyrrole Particles Using Reactive Polymeric StabilizersM. R. Simmons, P. A. Chaloner, and S. P. ArmesCite this: Langmuir 1995, 11, 11, 4222–4224Publication Date (Print):November 1, 1995Publication History Published online1 May 2002Published inissue…