Materials Literature
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Abstract Wholly aromatic polybenzimidazoles were synthesized from aromatic tetraamines and difunctional aromatic acids and characterized as new thermally stable polymers. The melt polycondensation of aromatic tetraamines and the diphenyl esters of aromatic dicarboxylic acids was developed as a general procedure of wid…
Abstract The solubility constants for thirteen permanent gases were measured within the temperature range 5–55°C. in a linear and a branched polyethylene, hydrogenated polybutadiene, and natural rubber. Equilibrium and time lag solubility determinations were made, the latter being indirectly obtained as the ratio of t…
Abstract Diffusion and permeability constants for twelve permanent gases have been measured in a linear and a branched polyethylene, hydrogenated polybutadiene, and natural rubber over the temperature range 5–55°C. The Barrer time lag apparatus has been used in these determinations. For all gas–polymer pairs investiga…
The thermal conductivities of single-crystal bars of several ferrites have been measured over the temperature range 1.4\ifmmode^\circ\else\textdegree\fi{} to 25\ifmmode^\circ\else\textdegree\fi{}K in both zero external magnetic field and in a field of about 9.4 kilo-oersteds. For each speciment the zero-field conducti…
Results are reported of a study of the contribution of spin or exchange polarization to the magnetic interaction of a rare earth ion with its neighbors and with its own conduction electrons. The rare earth ions carry a paired electron spin density which is negative in their outer reaches and these ions may even appear…
Sodium-ion vacancies are introduced into sodium chloride crystals by the addition of the following divalent cation impurities: ${\mathrm{Mg}}^{++}$, ${\mathrm{Mn}}^{++}$, ${\mathrm{Ca}}^{++}$, ${\mathrm{Zn}}^{++}$, ${\mathrm{Cd}}^{++}$, and ${\mathrm{Sr}}^{++}$. Below 150\ifmmode^\circ\else\textdegree\fi{}C, the virtu…
In an anisotropic ferromagnet the Curie temperature is a function of the direction of the magnetization. The Curie temperature is high in easy directions, and can drop quite low in harder directions for large ratio of anisotropy to exchange energy. Magnetization curves as a function of temperature also depend upon the…
Previous calculations of the instability threshold have been based on a plane-wave analysis which is strictly applicable only in an infinite medium. This paper describes a more rigorous theory in which the boundary conditions at the surface of the sample are taken into account. The refined theory admits instabilities…
Solid solutions based on sodium niobate with limited amounts of lead and zirconium or lead and titanium solute ions have been investigated with respect to their dielectric constant versus temperature at 1 kc. per second from −175° to 300°C. Lead zirconate additions to sodium niobate up to 15 mole % cause an increase i…
The author has summarized the results of thirty years’ research on the properties of powdered materials. These studies have been concerned with powders of all types, but most of the conclusions are applicable to metallic powders. The complex properties of powders can be resolved only by first defining those fundamenta…
The optical spectrum of the weak luminescence produced when water is irradiated by an intense ultrasonic beam has been determined. Water saturated with argon, helium, oxygen, or nitrogen was studied with the use of 800-kc radiation. The spectral distribution of the luminescence was measured with a spectrometer and pho…
A ferromagnetic parametric amplifier requiring fractional watts of pump power has been developed and investigated experimentally. The amplifier employs magnetostatic modes as resonances which are parametrically pumped by a longitudinal rf magnetic field. A theoretical discussion of the characteristics of longitudinal…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTProducts of the Thermal Decomposition of Some Cobalt Ammine AzidesTaylor B. Joyner and Frank H. VerhoekCite this: J. Am. Chem. Soc. 1961, 83, 5, 1069–1072Publication Date (Print):March 1, 1961Publication History Published online1 May 2002Published inissue 1 March 1961https:/…
Abstract The system cellulose triacetate in chloroform has been studied using the technique of dilatometry, viscometry, and light‐scattering, and it has been observed that although under certain conditions the solutions can be induced to gel, gelation occurs without the change in volume to be expected for a first‐orde…
Abstract Vulcanized latex was obtained by the γ‐irradiation of natural rubber latex. The optimum cure was attained with ca. 2 × 10 7 r, in the case of 40% latex. Owing to the acceleration action of the water present, rubber in latex crosslinked more easily than it did in previously dried latex film, but no appreciable…
Abstract Rates of mass transfer by free convection have been measured for spheres of three organic acids dissolving in three solvents, water, n ‐butanol and benzene. The results fell into two groups, one in which flow is completely laminar and one in which turbulence had set in in the boundary layer. Turbulence appear…
Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Seiichi Kanda, Shinichi Kawaguchi; Electrical Conductivity of Some Coordination Polymers. J. Chem…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStudies on l-Alkenyl Isocyanates and Their Derivatives1MASAO SATOCite this: J. Org. Chem. 1961, 26, 3, 770–779Publication Date (Print):March 1, 1961Publication History Published online1 May 2002Published inissue 1 March 1961https://pubs.acs.org/doi/10.1021/jo01062a031https:/…
This is the summary of a paper which discussed neutron diffraction techniques as applied to helical type and related spin structures, and illustrated these techniques with results from recent investigations on MnAu2 and metallic holmium.
Abstract A method of measuring the pH‐dependent cation‐exchange capacity of soils is described and data for 15 surface soils are presented and discussed. The pH‐dependent cation‐exchange capacity was found to be equivalent to the exchange acidity not displaced by a neutral KCl solution but displaced by buffered BaCl 2…