Materials Literature
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The glass-transition temperatures Tg of various copolymers of acrylonitrile and vinyl acetate were measured by observing the linear expansion of molded discs. For vinyl acetate contents of 0 to 27 wt-.% the glass temperature is constant at 87°C. This value agrees with the results of Kolb and Izard for pure polyacrylon…
An hochgereinigtem 4,4′-Di-methoxy-azoxybenzol (p,p′-Azoxyanisol) wurden die Hauptdielektrizitätskonstanten ε 1 und ε 2 und die dielektrische Anisotropie Δε der nematischen kristallinflüssigen Phase bei 0,10; 0,26; 0,65 und 1,60 MHz gemessen. Die Ergebnisse werden mit der in einer früheren Veröffentlichung entwickelte…
The macroscopic physical properties of a partially crystalline polymer become anisotropic when the polymer is `drawn', i.e. when the polymer undergoes a large permanent deformation from its isotropic state. The anisotropy of refractive index, X-ray scattering etc. has been investigated by many workers. In this paper t…
In the present paper we collect the available evidence from work-hardening curves, slip-line observations, and ferromagnetic measurements on the easy glide region of f.c.c. metals and alloys and the low-temperature work-hardening of hexagonal metals. New experimental results are reported on copper single crystals defo…
Copper single crystals subjected to a neutron dose of 3×1018 nvt (total flux) at pile temperature have been examined after deformation by the following experimental techniques: (a) observation of the load-extension relationships, (b) investigation of the slip-line structure with the electron microscope, and (c) diffra…
The results of the postirradiation examinations on UC compounds having nominal compositions of 4.6, 4.8, and 5.0 w/o C continue to be encouraging after irradiation to approximate burnups of from 1000 to 15,000 MWD/Ton of U. Density changes were small varying from a minimum of 0.7% to a maximum of about 2.5%. Cracking…
Abstract The experimental data collected on the interaction of active centers of carbon black with the rubber on the one hand and of the active centers of carbon black with the sulfur and accelerators, and also with the antioxidants, on the other hand, provide a sound basis for belief that the problem of reinforcement…
Treatment of unaccelerated natural rubber–sulfur vulcanizate networks with triphenylphosphine in benzene at 80°C. effects the removal of part of the combined sulfur, the proportion removed decreasing with increasing cure time. This partial desulfurization of the network is attributed, on the basis of the mode of inter…
Studies have been made of the emission spectra (3000 to 6000 A) obtained from low-pressure atomic oxygen-acetylene flames diluted with varying amounts of molecular oxygen and molecular nitrogen. Added molecular oxygen greatly increased the OH emission while reducing CH and C2 emission. It also had an effect on the rot…
Abstract On the basis of previous work, a model for the structure of cellulose fibers is proposed. The effect of degree of polymerization (DP), lateral order, and orientation on tensile properties is discussed in the light of this model. A program was set up to determine separately the effects of the different factors…
The well-known but little used concept of space filling proves to be an excellent method for presenting geometrical relationships of different simple crystal structures. By introducing the radius ratio into the equation for space filling it is possible to express space filling in a way which is independent of the part…
Abstract Various workers in recent years have found that the Gouy‐Chapman theory of the diffuse electrical double layer provides useful predictions of swelling behavior of certain 2:1 clays in dilute solutions. Calcium‐saturated montmorillonite was apparently an exception. It swelled appreciably in dilute CaCl 2 solut…
The absorption and fluorescence spectra of Nd3+ in NdCl3 diluted by LaCl3 have been examined with their Zeeman effect at 4.2° and less completely also at 77°K. The empirical energy-level diagram is complete up to 28 000 cm−1 except for the location of the 2K term. Crystal Stark splittings, magnetic properties, and int…
An empirical equation relating glass temperature, molar cohesion, and polymer structure has been developed from data found in the literature. A fairly extensive list of group cohesion values has been obtained from this relationship and glass temperatures which are in good agreement with reported values have been calcu…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTHE VAPORIZATION BEHAVIOR AND THERMODYNAMIC STABILITY OF ZIRCONIUM CARBIDE AT HIGH TEMPERATURE1B. D. PollockCite this: J. Phys. Chem. 1961, 65, 5, 731–735Publication Date (Print):May 1, 1961Publication History Published online1 May 2002Published inissue 1 May 1961https://pub…
Abstract Cellulose triacetate and triethyl cellulose have been crystallized from dilute solution into regular compact lamellar crystals of microscopic size (10–20 μ) and of the same type as the single crystals previously obtained from linear synthetic polymers The shape of the cellulose acetate crystals (pyramids with…
A study has been made of the growth of barium ferrite single crystals from a sodium carbonate flux. Crystals weighing up to 5.6 gm. have been grown by cooling melts slowly from about 1250°C. The phase diagram of the system BaO‐Na 2 O‐Fe 2 O 3 has been studied in the region of the BaFe 12 O 19 composition. The effects…
In the system $$NaAlSiO_{4}-KAlSiO_{4}-SiO_{2}-H_{2}O$$ the limits of solid solution of nepheline have been determined at 775°, 703°, and 500° C. The crystallization temperatures of a number of natural nephelines have been deduced using the experimental results. The possible chemical changes in the composition of neph…
A model is considered for the case of polycrystalline ferroelectrics in which each crystallite is presumed to behave according to a free-energy function of the type formulated by A. F. Devonshire [Advances in Phys. 3, 85 (1954)] for BaTiO3. The Curie temperatures for the individual grains are taken in a Gaussian distr…
The effect of point imperfections on lattice thermal conductivity is discussed with particular attention to the case in which the temperature is low but the normal three-phonon scattering is still dominant. The experimental results of Walker and Fairbank on the conductivity of isotopic mixtures of solid helium are ana…