Materials Literature
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The explosively driven oblique collapse of two metal plates has been studied numerically in order to deduce the interaction region structural details. Emphasis was placed upon circumstances leading to high-speed jet formation. It is shown that many of the features of metallic jets can be estimated easily from readily…
The effects of water vapor on the initial sintering of magnesia powder compacts were studied from 800° to 1107°C. The magnesia was obtained by thermal decomposition of magnesium oxalate. Water vapor partial pressures from 8 × 10 –4 to 658 mm were used. Initial sintering occurred by a grain‐boundary vacancy‐diffusion m…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFive-Coordinate Complexes. II.1 Trigonal Bipyramidal Copper(II) in a Metal Atom ClusterJ. A. Bertrand and James A. KelleyCite this: J. Am. Chem. Soc. 1966, 88, 20, 4746–4747Publication Date (Print):October 1, 1966Publication History Published online1 May 2002Published inissu…
Recent experiments on high strength steel having a very fine microstructure have been interpreted in terms of the Petch relationship with the apparent dislocation pile-up lengths as small as 85 Å. For this reason, the behaviour of such small dislocation pile-ups has been examined theoretically. The results indicate th…
The extracellular fibers attached to the diatom Thalassiosirafluviatilis have been shown to be pure β-(1 → 4)-linked 2-acetamido-2-deoxy-D-glucan. This polysaccharide was given the systematic trivial name chitan to distinguish it from chitin, which is not a chemically distinct species and which has a radically differe…
Abstract Torsional creep measurements on four natural rubber vulcanizates, crosslinked to different degrees, were carried out in the temperature range from −50 to 90°C. This investigation complements the studies on identical samples of the stress relaxation behavior by Chasset and Thirion and of the dynamic mechanical…
High nickel alloys and various analyses of Types 304L, 316 and 347 as well as European commercial steels off similar analysis were tested in high temperature (350 C - 662 F) demineralized water and steam (650 C - 1202 F) for varying periods up to five months. High-nickel austenites were found susceptible to intergranu…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe System Potassium Carbonate—Magnesium CarbonateS. E. Ragone, R. K. Datta, Della M. Roy, and O. F. TuttleCite this: J. Phys. Chem. 1966, 70, 10, 3360–3361Publication Date (Print):October 1, 1966Publication History Published online1 May 2002Published inissue 1 October 1966h…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCoordination Compounds with Delocalized Ground States. Bisdithiodiketone Complexes of Iron and Cobalt1G. N. Schrauzer, V. P. Mayweg, H. W. Finck, and W. HeinrichCite this: J. Am. Chem. Soc. 1966, 88, 20, 4604–4609Publication Date (Print):October 1, 1966Publication History Pu…
The crystallization of polypropylene droplets was investigated with the optical microscope. It is found that the droplets will undercool approximately 100 deg (Tm0=178°C). The undercooling attained for most of the droplets is increased by 1.43 deg when the cooling rate is increased by a factor of 10. An isothermal exp…
Abstract This paper presents a rigorous new theory of differential thermal analysis, taking account of the temperature gradient in the sample. From this consideration, a new quantitative method is proposed, where a solid-cell holder of low thermal conductivity is set between a sample cell and a metal block, and a ther…
The fluorescence of unactivated and rare-earth-activated materials of the type Ln2WO6, Ln2MoO6, and Y2W1−xMoxO6 (0≤x≤0.1) has been studied. From the experiments on unactivated materials it follows that energy transfer from tungstate to tungstate or mobyldate group takes place, whereas there is no transfer from molybda…
Abstract The structure of polypropylene crystallized at pressures up to 5000 atm. has been studied. Upon slow cooling from the melt at 320 atm., the γ modification, previously found only in low molecular weight and stereoblock fractions, begins to appear in small amounts in addition to the normal α monoclinic form. As…
Glass transition temperatures of a very wide molecular-weight range of ethylene oxide polymers were measured by mechanical loss and by broadline NMR. Starting at about −95°C for ethylene glycol, the glass transition rises to a maximum of −17° for molecular weight 6000 and then drops off to −53° for polymers with molec…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhosphonitrilic Compounds. VII. High Molecular Weight Poly(diaminophosphazenes)H. R. Allcock and R. L. KugelCite this: Inorg. Chem. 1966, 5, 10, 1716–1718Publication Date (Print):October 1, 1966Publication History Published online1 May 2002Published inissue 1 October 1966htt…
Microstructure of spherulites of the monoclinic modification of isotactic polypropylene has been studied in thin films by transmission electron microscopy and electron diffraction. Centers of spherulites are found to consist invariably of complex arrays of intercrossing lamellae. Radiating from the central regions are…
Abstract Thermal conversion rates of the polyamic acid derived from pyromellitic dianhydride and 4,4′‐diaminodiphenyl ether are presented. Formation of the imide ring proceeds by fast and slow first‐order processes. Tertiary amines give ring closures faster by a factor of 10 than the free acid. The enhancement is an a…
Fluorescence yields of solutions of several chelates of europium and terbium have been measured: (a) upon excitation in the ligand absorption bands and (b) upon selective excitation to individual upper levels of the rare-earth ion. Yields with upper-ion-level excitation are lower than when the emitting level is excite…
Variational principles have been applied to aggregates of randomly oriented pure-phase polycrystals having tetragonal symmetry. The bounds of the effective elastic moduli obtained in this way show a substantial improvement over the bounds obtained by means of the Voigt and Reuss assumptions. The Hill average is found…
Four rules are proposed to explain the photoluminescent efficiency of Eu3+-activated oxides: (a) uv absorbing groups in the host lattice should be nearest neighbors in the crystal structure to have sufficient wavefunction overlap; (b) the emission spectrum of the absorbing group should overlap the absorption spectrum…