Materials Literature
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Abstract Deterioration in poly(vinyl chloride) is due primarily to zipperlike elimination of hydrogen chloride from the polymer chain, with formation of colored and easily oxidizable polyenes. Baum and Wartman have shown that elimination is initiated by rupture of certain particularly labile carbon‐chlorine bonds. The…
The dielectric constant, and the ferroelectric, pyroelectric, and piezoelectric properties of thiourea crystals have been measured in the temperature range 90°K to 300°K. At least three dielectric anomalies are found at 169°K, 177°K, and 202°K, the lowest of these corresponding to a pronounced discontinuity. The cryst…
The amount of 90° reorientation during poling was determined from mechanical strains measured during the poling process. With tetragonal lead titanate zirconate 53% of the possible 90° reorientation occurred during poling, but this figure dropped to 44% upon removal of the poling field. With barium titanate the figure…
The reflectance and fluorescent spectra of hexagonal CdS crystals have been measured at 77\ifmmode^\circ\else\textdegree\fi{} and 4.2\ifmmode^\circ\else\textdegree\fi{}K using polarized light in the region of 5000 A. Structure not previously reported has been found in the reflectivity curves which leads to the identif…
The static boundary problems of line currents and dipoles immersed in a perfectly conducting static fluid are considered first. The perturbing effect of moving fluid on the magnetostatic boundary about an isolated line current is then investigated. In this case, the initial circular boundary is distorted into an ellip…
It is widely recognized that electron tube failures may be classified into two types: sudden and delayed. A mixture of two Weibull distributions, each representing one type of tube failure, is proposed, and a simple graphical method for estimating the parameters of the mixed Weibull distribution described.
Abstract The phenomenon of ferroelectricity in pseudo-cubic crystals is discussed in terms of the normal modes of vibration. It is shown that the parameters which determine the lattice vibrations of a diatomic ionic crystal may be chosen in such a way that the crystal will exhibit ferroelectric properties, and that fe…
We have derived, by using simple considerations, a relation between the diffusion constant D in a liquid of hard spheres and the ``free volume'' vf. This derivation is based on the concept that statistical redistribution of the free volume occasionally opens up voids large enough for diffusive displacement. The relati…
The fuel element cans of most of the current gascooled graphite- moderated reactors are not bonded to the uranium fuel. Good contact between can and fuel is ensured by a pressurizing operation during the canning process. The temperature drop at the interface will be small compared to the can-to-gas temperature drop, b…
X-ray topographs of a new type have revealed fine fringes in the diffraction images of wedge-shaped parts of perfect and nearly perfect crystals. The fringes are analogous to those seen in electron microscope images of wedge-shaped parts of magnesium oxide crystals and can be interpreted according to the theory applic…
This test method has been described in an earlier publication; it has been adopted in the United Kingdom as Method 102-D of British Standard 2782 (1956) and in the United States by ASTM. One advantage of the Vicat softening point (VSP) test is that it can be carried out on small specimens. It was therefore of interest…
George C. West; Effects of High Air Temperature on the Bill and Claw Keratin Structures of the Tree Sparrow, The Auk, Volume 76, Issue 4, 1 October 1959, Pages
Abstract The chemical reactions of polymers promoted by mechanical energy are surveyed. Evidence is reviewed in support of a mechanico‐degradation of polymers subjected to shear and of scission occurring in the central sections of the longer polymer molecules. The action of oxygen, “peptisers” for rubber degradation,…
The intrinsic viscosity of a polymeric substance crosslinked as well as degraded by irradiation with high-energy radiations is discussed for various types of initial molecular size distributions. The intrinsic viscosity as a function of radiation dose is shown to behave in a great variety of ways depending on the rela…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Kinetics of Oxidation of HBrWillis A. Rosser Jr. and Henry WiseCite this: J. Phys. Chem. 1959, 63, 10, 1753–1755Publication Date (Print):October 1, 1959Publication History Published online1 May 2002Published inissue 1 October 1959https://pubs.acs.org/doi/10.1021/j150580a…
Machine learning (ML) is transforming all areas of science. The complex and time-consuming calculations in molecular simulations are particularly suitable for an ML revolution and have already been profoundly affected by the application of existing ML ...Read More
Schlieren techniques have been used to study the effects of ultrasonic waves on concentration gradients produced by electrochemical methods. With standing waves at intensities below cavitation levels, the zones of depleted electrolyte at the cathode stratify at the displacement nodes of the standing waves while the zo…
The self-diffusion of nickel has been studied in polycrystalline samples by a sectioning technique. There is evidence of grain boundary diffusion below temperatures of 1150 °C. The results obtained between 1150° and 1400 °C are representative of volume diffusion and are represented by the expression[Formula: see text]…
An experimental survey of additives to barium titanate shows that in addition to those which are readily soluble in the barium titanate lattice (class 1) and those which are insoluble (class 2) two other distinct classes of additive, with limited solid solubility (classes 3 and 4), can be distinguished. Class 3 additi…
Density measurements have been made on vacuum-deposited copper films in the thickness ranges 50 to 150 A and 500 to 1000 A. To obtain the density, an analysis was made of the relation between the reflection coefficient and the glancing angle of incidence for 1.54 A x-rays. For films in the range 500 to 100 A, this ana…