Materials Literature
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Abstract Reactions on the reactive groups of macromolecular substances (e.g., cellulose) have long been known, even since before the structures of macromolecules were understood. H. Staudinger carried out numerous reactions with macromolecules, maintaining the degree of polymerization constant, in order to substantiat…
Flexural strengths of specimens prepared from four uranium dioxide powders were determined at room temperature and at 1000°C. The relation of the strength (S) to porosity (P) and to grain size (G) could be represented by the expression S = kG −a e −b P , where k, a , and b are empirical constants which differed with t…
A mechanistic analysis of fabric flexure is outlined, relating fabric behaviour to fibre properties through the geometry of the structure, particularly as it is affected by fibre interactions. The influence of two factors is discussed : first, the degree of fibre association or clustering which exists within the yarn;…
Abstract It has been found that storage hardening in rubber is inhibited by certain amines and reagents for carbonyl compounds. The technological importance and theoretical significance of these observations are discussed. It is postulated that carbonyl groups present in the rubber molecule are responsible for crossli…
The activation of a band in the absorption spectrum of a type IIa diamond was accomplished using fast neutrons. The absorption spectra taken before and after a dose of 3 x 10/sup 17//cm/sup 2/ are shown. Strong continuous absorption is evidenced following irradiation, beginning sharply at the Raman energy and extendin…
Abstract The polymerization of propylene oxide at 80°C. catalyzed by aluminium trimethyl has been studied kinetically, using a dilatometric method combined with a high‐vacuum technique to exclude adventitious water and oxygen. Both in bulk and in methylene chloride solution, the reaction is not stereospecific in the a…
Recent observations of the growth of quenched-in dislocation loops during annealing are discussed. A mechanism for the coalescence of loops is proposed. The mechanism depends on short-circuit diffusion around the periphery of prismatic dislocation loops. This mechanism is contrasted with the theory of loop coalescence…
In a previous paper, an attempt was made to reduce the theoretical coercive force by assuming that the magnetocrystalline anisotropy constant vanished in a certain region. A modification of this assumption was made in the present work, namely, the magnetocrystalline anisotropy was taken as zero in a part of the "imper…
Electron microscope studies of the tracks produced by fission fragments in thin films of UO2 have established a 100% detection efficiency for fission events in films 100 A or less in thickness. A background texture decreases the efficiency in thicker films. The tracks register in the films primarily as a result of a r…
Abstract The solid state polymerization of acrylamide and related monomers has been studied using the tools of electron spin resonance and optical microscopy. The data indicate that the reaction involves free radicals which do not terminate in the usual fashion. The reaction apparently involves a nucleation mechanism…
First order phase transitions were investigated for n-nonane, n-dodecane, n-tridecane, n-pentadecane, n-octadecane, and n-tetracosane, at pressures up to 10 kilobars and temperatures up to 135°C. By a modification of standard piezometric techniques, phase transition pressures, as well as the associated isothermal isob…
The electron microscope has been, used to examine point defect clusters produced in copper and aluminium foils bombarded with l·4 × 1017 alpha-particles cm−2. The foils were bombarded as a stack and, in copper, both those through which the alpha-particles had passed and that in which they came to rest appeared similar…
The characteristic electron energy loss spectra of the elements of the first group of transition metals, Ti to Cu, have been obtained using the reflection technique. In the spectrum of each metal one loss peak is identified as a plasma loss, and another, except in Ti and V, as a lowered plasma loss. Two other series o…
The increases of the magnetic susceptibilities with temperature for non-ferromagnetic transition metals are investigated by making use of the band picture. If the Fermi surface at the absolute zero of temperature is in the neighbourhood of a minimum of the electron state density, the susceptibility increases with temp…
A theory is developed about the molecular size distribution in a system of copolymers which are composed of two different kinds of monomer units and undergo random crosslinking when exposed to high-energy radiations. The radiation-induced change in the molecular size distribution is described by an integro-differentia…
In addition to the α solid solution of arsenic in copper, three intermediate phases exist in the copper/arsenic system. The ε phase, stable only below ca. 340 °C, has the hexagonal A3 [Formula: see text] structure with a = 2.588, c = 4.226 Å, and the approximate formula Cu 8 As. The compound Cu 3−x As with 0 ≤ x ≤0.3,…
Measurements have been made of the variations with temperature of the intensities of x-ray diffraction lines from silver and iron. For silver the measurements were in the range 286–1100°K, and the Debye-Waller temperature factor corresponded to a characteristic temperature of 197°K at 286°K. For iron the measurements…
The univariant equilibrium pressure‐temperature curve along which β‐MnO 2 , Mn 2 O 3 , and O 2 are stable together has been determined up to a Po 2 of 200 atmospheres with a trace of water as a catalyst. The analogous curve for the assemblage Mn 2 O 3 , Mn 3 O 4 , and O 2 has also been determined. In both cases the ex…
Studies of dislocations in elongated aluminum crystals by diffraction electron microscopy revealed narrow dislocation loops lying parallel to 〈112〉. These loops formed only behind screw dislocations, their long parts then having edge character. Four mechanisms have been proposed to account for the formation and stabil…
Infrared absorption spectra have been obtained in the 430 to 4000 cm—1 region for B3O3(OH)3, B310O3(OH)3, and B3O3(OD)3, as polycrystalline mulls and, in the case of B3O3(OH)3, as a single crystal section. A partial Raman spectrum has been obtained for B3O3(OH)3 in the polycrystalline form. The spectral data have been…