La preparación de las muestras para análisis por rayos X. II. Difracción
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Cut growth and fatigue of rubbers. II. Experiments on a noncrystallizing rubber
Abstract Tensile fatigue failure of a gum vulcanizate of noncrystallizing SBR can be accounted for by the growth of small flaws initially present in the rubber. Fatigue of crystallizing natural rubber was shown in Part I to be attributable to the same cause. Cut growth results are interpreted in terms of the tearing e…
Preparation and Characterization of the Lower Equilibrated Phenylsilsesquioxanes
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation and Characterization of the Lower Equilibrated PhenylsilsesquioxanesJohn F. Brown, Lester H. Vogt, and Paul I. PrescottCite this: J. Am. Chem. Soc. 1964, 86, 6, 1120–1125Publication Date (Print):March 1, 1964Publication History Published online1 May 2002Published…
Thermoluminescent Kinetics of Alpha-Irradiated Alkali Halides
The kinetics of the thermoluminescence of single crystal NaCl, KCl, and KBr irradiated with 40-MeV alpha particles were investigated. Only one glow peak, composed essentially of a single emission band, was obtained for each of the salts investigated. To attempt complete analysis of the kinetics, both glow curve and is…
Dead-End Pore Volume and Dispersion in Porous Media
Abstract Experiments in which calcium chloride displaced sodium chloride from four cores showed the extent of asymmetry in the resulting effluent concentration profiles. These results provided a check on how validly the mixing process is modeled by a differential (i.e., not finite-stage) capacitance mathematical model…
SELF-DIFFUSION AND INTERDIFFUSION IN POLYMER SYSTEMS
CONTENTS I. Introduction 103 II. Methods for the experimental investigation of self-diffusion and interdiffusion in polymer systems 103 III. Mechanism of self-diffusion and interdiffusion of polymers 105 IV. Influence of time, temperature, and concentration on self-diffusion and interdiffusion in polymers 106 V. Influ…
Thermal Denaturation of Collagen in the Dispersed and Solid State
Thermal denaturation temperature of newly reconstituted collagen fibrils from rat tail tendons is 52 degrees C compared with 42 degrees C for neutral solutions. This suggests that the increase in concentration of collagen within the fibril increases the stability of the individual molecules. The absence of firm interm…
FERROMAGNETISM AND ANTIFERROMAGNETISM OF RARE-EARTH METALS
CONTENTS 1. Magnetic Properties of Rare-earth Ferromagnets 179 2. Neutron-Diffraction Studies of the Magnetic Structure of Rare-earth Ferromagnets 183 3. Theory of the Helicoidal Magnetic Structure 184 4. Nature of Magnetic Phase Transitions in Rare-earth Ferromagnets 190 5. Antiferromagnetism of Metals of the Cerium…
Crystalline morphology in thin films of natural rubber II. Crystallization under strain
Abstract The morphology of thin films of natural rubber crystallized under unidirectional strain has been examined in the electron microscope. As strain increases the spherulitic morphology of unstrained films gives way gradually to a fibrillar morphology with crystalline filaments (α filaments) measuring 60 by 250 Å,…
Temperature Dependence of the Width and Position of theE2→A24Fluorescence Lines ofCr3+andV2+in MgO
The energy levels of an impurity ion in a solid are in general shifted and broadened by thermal vibrations of the host lattice. A study of these effects in a simple system can lead to some understanding of the phonon-impurity interaction. This paper reports measurements of the width and positions of the sharp fluoresc…
Exchange Interactions in Cu(NH3)4SO4·H2O
Considering the specific heat, the magnetic susceptibility, and the crystal structure of Cu${(\mathrm{N}{\mathrm{H}}_{3})}_{4}$S${\mathrm{O}}_{4}$\ifmmode\cdot\else\textperiodcentered\fi{}${\mathrm{H}}_{2}$O, we conclude that this substance has the magnetic linear chain property. The ratio of the exchange integrals $|…
Exact Solution of Generalized Percus-Yevick Equation for a Mixture of Hard Spheres
The Percus-Yevick approximate equation for the radial distribution function of a fluid is generalized to an $m$-component mixture. This approximation which can be formulated by the method of functional Taylor expansion, consists in setting $\mathrm{exp}[\ensuremath{-}\ensuremath{\beta}{\ensuremath{\phi}}_{\mathrm{ij}}…
Some Dielectric Properties of Tantalum Pentoxide
The dielectric constant and dissipation factor of β- and α-Ta2O5 ceramics and of plates cut from a boule of α-Ta2O5 have been measured from 77° to 373° K over a frequency range from 100 cps to 100 kc/sec. β-Ta2O5 ceramics behave as typical dielectric materials. On the other hand, α-Ta2O5 ceramics exhibit large migrati…
Intrinsic edge absorption in diamond
Abstract The optical transmission spectra of several diamonds have been studied over the range 5·0 to 6·0 eV (2450 to 2000 Å) and at many temperatures between 90 and 600 °K. The reflexion spectrum was also recorded between 5 and 14 eV (2450 to 900 Å) at 295 °K and between 5 and 8 eV (2450 to 1550 Å) at 133 °K. The int…
Atomic coordinates of AlPO4
The X-ray powder diffraction data on A1PO 4 have been obtained on a diffraetometer. The system is found to be trigonal with cell constants a =4.941 /~, c = 10.95 /~ and space group P3121. From the known similarity between ALP04 and s.quartz, the atomic coordinates have been determined to be O(1): x = 0.275, y = 0.406,…
Crystal structure of a sodium cobalt molybdate
The sodium cobalt molybdate studied here crystallizes in space group D16-Pnma of the orthorhombic system in a cell of dimensions a = 5.25, b = 10.78, 2h c 18.02 A.
Crystallinity in isotactic polyolefins with unbranched side chains
Abstract The crystalline forms of several isotactic unbranched polyolefins in the series polyhexene‐1 to polyoctadecene‐1 have been investigated by X‐rays. Polytetra‐, ‐hexa‐, and ‐octadecene‐1 each crystallise three‐dimensionally in two forms, Types I and II. Both types give characteristic diffraction patterns and al…
Electric-Field Gradient Tensor in Ferrous Compounds
The electric-field gradient tensor at the iron nucleus in ferrous (${\mathrm{Fe}}^{2+}$) compounds is investigated. One sees that under the combined action of axial and rhombic crystalline fields and the spin-orbit interaction, the ferrous-ion $(^{5}D,3{d}^{6}){d}_{\ensuremath{\epsilon}}$ states produce a large, tempe…
Fulminen (1.2‐Benzo‐picen) im Steinkohlenteer
Abstract Ein sehr stabiler farbloser Kohlenwasserstoff, genannt Fulminen, wurde aus den höchstsiedenden Anteilen des Steinkohlenteers isoliert. Seine wahrscheinliche Konstitution ist die des 1.2‐Benzo‐picens (I).
Crystallographic study of xylan from wood
Abstract Some preparations of xylan in the form of transparent membrance or amorphous powder prepared from deciduous woods such as beech and birch show a number of Debye‐Scherrer rings at the irradiation with x‐ray. Of special interest from the crystallographic standpoint is the diffraction pattern of the membrane, wh…