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Methods for measuring various storage moduli and damping factors of glassy polymers in the frequency range 10−2 to 10−7 Hz are critically reviewed. At frequencies between about 10−2 and 200 Hz, components of the complex tensile modulus E∗ and complex Poisson's ratio ν∗ have been determined at 21 °C for polymethyl meth…
Abstract The structure of a lepidolite-2 M 1 from Biskupice, Czechoslovakia, has been redetermined. Violations of systematic extinctions and of monoclinic equivalences plus the results of a second harmonic generation test indicate that the true symmetry most likely is C 1̄. The deviation of the data set from C 2/ c sy…
Abstract A process that uses terephthalic acid and excess 1,4‐butanediol for the production of polybutylene terephthalate was investigated and the reaction conditions were maximized for fast reaction and minimal loss of butanediol by dehydration to tetrahydrofuran. For best results a mixed catalyst was selected: butyl…
Abstract The crystal structures of Eu2B5O9X (X=Cl and Br) were determined by the method of X-ray diffraction analysis and refined by the least-square method to give R=0.054 for 1967 observed reflections of Eu2B5O9Cl and R=0.047 for 1979 observed reflections of Eu2B5O9Br. These haloborates are isostructural and belong…
Abstract In this article, the polycondensation of terephthaloyl chloride and p ‐phenylenediamine was systematically studied, including the liquid–crystalline state of the solution and the spinning of poly(1,4‐phenyleneterephthalamide) (PPTA). High‐molecular‐weight PPTA with ε inh = 5–7 was prepared and the main factor…
Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation H. W. Gao, S. Ramachandran, E. B. Christiansen; Dependency of the Steady‐State and Transient Visc…
Magnesium metal immersed in thionyl chloride solutions becomes covered by a passivating layer which has properties of solid electrolyte. The buildup and the electrochemical properties of this layer were studied. Tafel slopes measured on freshly immersed Mg electrodes depend linearly on the apparent thickness of the SE…
The current theoretical formulations of optical absorption by small metal particles are critically reviewed. Several inconsistencies of the usual dielectric-function calculations are noted, and an improved expression is proposed. The results indicate that optical spectra should have a bearing on the difficult question…
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Abstract Pairs of four thermoplastic resins, polystyrene, poly(methyl methacrylate), acetal homopolymer, and nylon‐12, were intensively melt‐blended in nine proportions from 0 to 100 percent. Capillary rheometry at 210°C was done on each blend; melt densities were also measured on most of them. The dependence of shear…
The structure of a bartonite crystal from Coyote Peak, Humboldt County, California, has been solved and refined in anisotropic mode to a conventional R = 0.068for 504 observed reflections. The tetragonal unit cell [space group 14/mmm, a = 10.424(1), c = 20.626(1)A] contains 2 formula units, which were found by site-oc…
A large enough DC or low frequency AC field couples to the permanent polarization P and unwinds the helical texture of a smectic C* liquid crystal.′ From the measurement of the unwinding critical field, one can deduce the value of P. We present here a general model to compute the unwinding critical field; this model t…
Radiofrequency (rf) cold plasmas of argon, nitrogen, and air were used to modify cotton fabrics and yarns. Changes in surface characteristics were detected by application of the techniques of electron emission spectroscopy for chemical analyses (ESCA), electron spin resonance, and chemiluminescence. Examples of polyme…
Abstract In Mg‐ and Ca‐doped α‐Al 2 O 3 crystals irradiated by X‐rays at 80 K new paramagnetic colour centres are observed having an absorption band at about 255 nm and an emission band at 310 nm. The hyperfine structure of the EPR spectrum indicates that the unpaired electron spin interacts mainly with two Al 27 nucl…
The annealing of the electrical resistivity of two high-purity austenitic Fe-Cr-Ni alloys, and of Si- and Ti-doped samples has been investigated after neutron irradiation at 23K. The resistivity variations (a decrease below 190K, an increase between 190 and 600K, and a decrease above 600K) can be understood in terms o…
Secondary Langmuir-wave decay into another Langmuir wave and an ion-acoustic wave is shown to provide a very efficient saturation mechanism for two-plasmon decay and stimulated Raman scattering. Near the quarter critical density, where two-plasmon decay dominates Raman scattering, large ion fluctuations are expected a…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInvestigation of axial anionic ligand and porphyrin substituent effects on the oxidation of iron(III) porphyrins: porphyrin-centered vs. metal-centered oxidationMartin A. Phillippi, Eric T. Shimomura, and Harold M. GoffCite this: Inorg. Chem. 1981, 20, 4, 1322–1325Publicatio…
The polarization reversal of some tetragonal-phase PLZT ceramics is studied. The results are explained in terms of 90° domain wall motions. A reported theory originally derived for rhombohedral-phase PLZT 6/65/35 ceramics is shown to be applicable to tetragonal-phase PLZT ceramics also by introducing the remanent degr…
Abstract K-bentonites of the Middle Ordovician High Bridge Group along the Cincinnati arch are characterized by interstratified illite/smectite (I/S) clays with rectorite-type ordering. Approximately 20% of the layers are expandable. They are structurally similar to I/S formed at temperatures exceeding 100°C during bu…
Tb3+ and Eu3+ bound to troponin C were detected by (1) changes in the fluorescence of the tyrosine chromophore of the protein or (2) the luminescence of the ions themselves excited by energy transfer from the protein or by direct excitation using a pulsed laser light source [Horrocks, W. DeW., Jr., & Sudnick, D. R. (1…