Materials Literature
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Abstract A mathematical model is used to predict the behavior of the support/catalyst/polymer macroparticle during the gas phase polymerization of propylene. The problem is focused on the micrograin level of the macroparticle, and the emphasis placed on the combined reaction and diffusion processes taking place in the…
Previous studies show that stress corrosion crack growth in glass is controlled by chemically enhanced crack tip bond rupture reactions. The brittle nature of fracture in glass suggests that the region where bond rupture reactions occur must be on the order of the atomic spacings in the material. Crack growth kinetics…
Surface preparation techniques of aluminium for adhesive joining in aerospace applications and their influence on bond formation have been reviewed. The mechanisms of the different pretreatments have been discussed with attention to the effect of alloying elements and conditions of the technique. On the basis of the m…
The initial reactions in two proposed gas-phase synthesis of interstellar ammonia have been studied in detail. The rate of the slightly endothermic reaction N+(H2) --> NH+(H) under interstellar conditions has been reinvestigated under thermal and nonthermal (translational excitation) conditions based on low-temperatur…
Abstract A new approach to the interpretation of Mössbauer spectra of Fe 3+ -phyllosilicates having vacant trans-octahedra is based on (1) crystal structure simulation methods that allow for the size and the shape of a Fe 3+ -octahedron as a function of the nearest surrounding cations; and (2) calculations of electric…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTheory of dynamic scattering from copolymer solutions using the random phase approximationM. Benmouna, H. Benoit, R. Borsali, and M. DuvalCite this: Macromolecules 1987, 20, 10, 2620–2624Publication Date (Print):October 1, 1987Publication History Published online1 May 2002Pu…
We present a combined experimental/theoretical study of the coverage and frequency dependence of surface (enhanced) resonance Raman scattering [S(E)RRS] of cobalt phthalocyanine (CoPc) on CaF2 roughened silver films. The experimental spectra indicate a rather strong coverage dependence at very low coverage for excitat…
We report the evolution of diffuse intensity during the low-temperature ageing of Al-Mn quasicrystals. This is taken as evidence of short-range order in the icosahedral phase prior to its decomposition. The implication of these diffuse intensities is discussed
We have obtained a complete set of 20 variants of the alpha subunit of tryptophan synthase of Escherichia coli at position 49 in order to extend our previous studies on the effects of single amino acid replacements at position 49 on structure and function. Thirteen mutant alpha subunits have been newly constructed by…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPara-linked, aromatic, thermotropic polyesters with low mesophase temperaturesR. Sinta, R. A. Gaudiana, R. A. Minns, and H. G. RogersCite this: Macromolecules 1987, 20, 10, 2374–2382Publication Date (Print):October 1, 1987Publication History Published online1 May 2002Publish…
Starting powders containing 72 wt% Al 2 O 3 and 28 wt% SiO 2 , were prepared by sol‐gel methods classified as colloidal and polymeric. Compacts fired at 1700°C showed significant differences in microstructure. The specimens formed with the colloidal powder had mullite grains of prismatic shape and a liquid phase; with…
We report the results of elastic and quasielastic light scattering measurements on dilute aggregates of colloidal silica. The elastic scattering measurements indicate a fractal dimension of 2.05\ifmmode\pm\else\textpm\fi{}0.06, in agreement with previous results, but the quasielastic measurements demonstrate several n…
A computer program has been developed for the Rietveld analysis of time-of-flight neutron diffraction data taken on a high-resolution powder diffractometer, HRP, at the pulsed spallation neutron source, KENS. A new profile shape function is implemented which is optimized for a solid-methane moderator at 20 K. The prog…
Fatigue crack propagation under tension‐tension loading is observed in a transformation‐toughened partially stabilized zirconia (PSZ) ceramic containing 9 mol% MgO. Such subcritical crack growth behavior is demonstrated to be cyclically induced, based on a comparison with behavior under sustained loading (at the maxim…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDirect evidence for cocrystallization in binary mixtures of ferroelectric copolymersHajime Tanaka and Andrew J. LovingerCite this: Macromolecules 1987, 20, 10, 2638–2640Publication Date (Print):October 1, 1987Publication History Published online1 May 2002Published inissue 1…
Abstract A significant reduction on the time for thermal crystallization of Bisphenol‐A polycarbonate has been achieved by means of a previous crystallization step of the polymer in acetone, followed by a capillary extrusion processing at temperatures above its melting range (230–280°C). The crystallinity of PC was co…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUse of multiplicity features for kinetic modeling: carbon monoxide oxidation on platinum/aluminaMichael P. Harold and Dan LussCite this: Ind. Eng. Chem. Res. 1987, 26, 10, 2099–2106Publication Date (Print):October 1, 1987Publication History Published online1 May 2002Publishe…
Abstract The problem of end effects influencing the ejection angles of fragments near the ends of cylindrical warheads is approached semi‐empirically. A correction term is added to the Taylor angle, based on the accepted concept that the reduced fragment velocities near the ends of a warhead are due to release waves i…
An attempt has been made to investigate the effects of aluminium, titanium, nitrogen, and boron on the hardenability of boron-bearing medium-carbon steels. It was found that not only titanium but also boron had the scavenging effect for dissolved nitrogen. A parameter designated as boron potential (Bp = xB−11/14(xN−14…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis of poly[(acyloxy)aloxane] with carboxyl ligand and its utilization for the processing of alumina fiberYoshiharu Kimura, Shozo Sugaya, Toshiaki Ichimura, and Isoji TaniguchiCite this: Macromolecules 1987, 20, 10, 2329–2334Publication Date (Print):October 1, 1987Publ…