Materials Literature
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The synthesis of polyphenylquinoxalines (PPQ) is discussed in detail. Solutions of PPQ at 20% solids content from stoichiometric quantities of pure reactants are generally metastable, increasing in viscosity and, in some cases, gelling. This can be alleviated without any appreciable detrimental effect upon the polymer…
The Fraunhofer diffraction patterns of the triangle, trapezoid, and hexagon are calculated and displayed in moiré plots. The diffraction pattern of the general polygonal aperture with a finite number of vertices can be calculated in terms of elementary functions.
The glass transition temperatures of linear and four- and six-branched regular star polystyrenes are measured by penetration, differential scanning calorimetry, and a density gradient technique. The results of the three methods show that the glass transition temperature depends on the concentration of chain ends in th…
Measurements are presented of the dielectric constants of some p,p′-n-alyl and n-alkoxy substituted azobenzenes and azoxybenzenes in the nematic and in the isotropic phase. Starting from the dipole-less, p,p′,di-n-alkyl-azobenzenes, a systematic interpretation is given of the influence of the molecular structure on th…
A Philips E.M. 300 electron microscope operating in the dark field high resolution mode has been used to study the size dependence of the melting points of individual particles of indium. The straight line graph, obtained from a simple thermodynamic treatment of the results, shows that the surface tension at the inter…
A new method which eliminates some disadvantages of the Epstein method has been developed for the rapid measurement of core losses and permeabilities at 50 or 60 Hz of single-sheet specimens. It is shown that the instrument has the following performance: 1) good correlation of the measured value with Epstein testing,…
Abstract The luminescence spectra of ZnO platelets at 1.9 K have been investigated under 3371 Å Insor excitation from 5 to 500 kW/cm 2 . New details in the P‐band luminescence (exciton‐exciton scattering) reveal the separation between A and B excitons in ZnO and the stimulated emission in this band is found to be stro…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStarch-Filled Polyvinyl Chloride Plastics-Preparation and EvaluationRichard P. Westhoff, Felix H. Otey, Charles L. Mehltretter, and Charles R. RussellCite this: Ind. Eng. Chem. Prod. Res. Dev. 1974, 13, 2, 123–125Publication Date (Print):June 1, 1974Publication History Publi…
The electrical conductivity and ion/electron transference numbers in Al 3 O 3 were determined in a sample configuration designed to eliminate influences of surface and gas‐phase conduction on the bulk behavior. With decreasing O 2 partial pressure over single‐crystal Al 2 O 3 at 1000° to 1650°C, the conductivity decre…
Interaction potentials of many ion pairs are calculated using the model presented in our previous paper [J. Chem. Phys. 56, 3122 (1972)]. In the calculation of the interactions of two ions, the electron density of the combined system of the ions is assumed to be equal to the sum of the two separate ionic electron dens…
We investigate some kinetic properties of an isotopically disordered harmonic crystal. We prove rigorously that for almost all disordered chains the transmission coefficient of a plane wave with frequency ω, tN(ω), decays exponentially in N, the length of the disordered chain, with the decay constant proportional to ω…
H J Zeiger and G W Pratt Oxford: Clarendon Press 1973 pp xv + 660 price £19.50 Magnetic fields are among the most powerful tools available for the study of the eigenstates of electrons whether these electrons are in free motion, bound in isolated atoms or bound in a condensed phase of matter. The perturbation induced…
The far infrared spectrum of each ionic metal-metaphosphate glass, (MPO3)n (M = Li, Na, K, Rb, Cs) and [M(PO3)2]n (M = Ca, Sr, Ba), contains a broad absorption band whose peak frequency, ω0, and halfbandwidth, Δω1/2, are strongly dependent on the mass and charge of the glass-modifying cation. Each such band, which app…
A general theory of multilayer adsorption from a polymer solution at an interface is presented. The free energy of the solution in the presence of a plane surface is evaluated in the quasicrystalline model. The configurational entropy of placing a linear chain molecule in the liquid medium of nonuniform concentration…
Four varieties of asbestos are used in the plastics industry: chrysotile, crocidolite, amosite, and anthophyllite. Some are used as raw fiber, felts, cloth yarns, and paper. Asbestos wets out in resin systems but is difficult to disperse. Because of its high chemical reactivity, under certain conditions it tends to ca…
A simple technique of measuring the dynamic magnetostriction in silicon-iron using displacement transducers is discussed. The importance of stress and harmonics of magnetostriction is shown by considering the effects of improving the stress sensitivity of steel and reducing core vibration by a suitable bonding techniq…
Data on resistivity at room temperature in polycrystalline and single-crystal Permalloy (80 Ni-20 Fe) thin films are analyzed in terms of grain boundary scattering and the dc size effect, respectively.
An attempt has been made to equate quantitatively the coercive force as a function of the grain size and the concentration of nonmagnetic inclusions. It was found that the coercive force Hcof recrystallized 47.5% nickel-iron can be completely described, independent of the final anneal temperature, by the grain size dK…
Laser-excited fluorescence measurements have given rate constants for the vibrational deactivation of NO(v=1) by NO, He, and N2, and for the V–V exchange between CO(v=1) and NO(v=1) in the temperature region 100–300°K. Relaxation was caused entirely by bimolecular collisions. Deactivation rates of NO(v=1) by H2O, D2O,…
For more than 30 years, Polymer Engineering & Science has been one of the most highly regarded journals in the field, serving as a forum for authors of treatises on the cutting edge of polymer science and technology.