Materials Literature
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Abstract Polyimide films from 4,4′‐diaminodiphenyl ether and pyromellitic dianhydride were pyrolyzed at 400–600°C. in non‐oxidative systems. Major gaseous products were carbon monoxide and carbon dioxide; hydrogen evolution occurred above 525°C. A mobile n ‐imide‐isoimide equilibrium is in accord with the gas evolutio…
The theory of grain growth in the presence of a liquid phase is examined using modifications of equations derived for coalescence of solid particles widely dispersed in a liquid. Although the grain diameter‐time relation can still be represented by d 3 = kt , the absolute growth rates are increased as the amount of li…
Abstract Von denen über Schmelzreaktionen in einer Stickstoffatmosphäre dargestellten Verbindungen KFeS 2 , RbFeS 2 und CsFeS 2 besitzt das RbFeS 2 nach Einkristalluntersuchungen einen dem KFeS 2 analogen Strukturaufbau (C 2h 6 –C2/c; Z = 4; a = 7,22; b = 11,70; c = 5,42 Å; β = 112,0°). CsFeS 2 kristallisiert rhombisc…
Abstract The morphology of the quenched form of polypropylene was investigated. Thin films of the quenched form consist of small ball‐like structures which we suggest are defective hexagonal crystals. In thicker films they aggregate to form spherulites with no observable fine structure. Quenching of thin films of molt…
The structures of thiourea, SC(NH2)2, and deuterated thiourea, SC(ND2)2, have been determined at room and liquid nitrogen temperatures from three-dimensional neutron diffraction data. No significant structural change on deuteration has been found. N—H⋯S hydrogen bonds occur in both materials at both temperatures with…
Abstract A procedure was developed for the determination of Si directly in citrate‐dithionite extracts of soils. The procedure, which provides for noninterference by citrate, dithionite, Fe, and P was developed for measurement of the absorbance of the reduced β‐molybdosilicic acid in the working range of 5 to 25 µg of…
Values of the parameter Vg/Vg are calculated for 100 kv electrons as a function of the reflection vector g for different crystal temperatures and for a number of different materials. It is shown that the usual assumption made, namely setting V0 ′ = Vg ′ = 0·1 Vg independent of g or material, is often a very poor appro…
Mason G. Fenwick, Lake Huron Distribution of Tabellaria fenestrata var. geniculata A. Cleve and Coelastrum reticulatum var. polychordon korshik, Transactions of the American Microscopical Society, Vol. 87, No. 3 (Jul., 1968), pp. 376-383
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEnthalpy of formation of cerium sesquioxideFloyd B. Baker and Charles E. HolleyCite this: J. Chem. Eng. Data 1968, 13, 3, 405–407Publication Date (Print):July 1, 1968Publication History Published online1 May 2002Published inissue 1 July 1968https://doi.org/10.1021/je60038a03…
Abstract Physical and mechanical properties of block copolymers are compared and correlated with the corresponding random copolymers. The important properties of melting point, transition temperatures, tensile strength, modulus, and elastic properties depend upon the structural arrangement of the molecular units compr…
Abstract Oxazolines containing carbomethoxy‐, acetoxy‐, and hydroxy‐alkyl groups on the side chain were prepared and polymerized. The properties of the polymers were investigated.
When the grain size dependence of dislocation density is applied to Cottrell's theory of the Portevin–Lechatelier effect, the result indicates that the critical strain ε0, necessary to initiate serrated flow, should depend on the grain size μ, at constant strain rate, according to the relationship ε0 = (constant)μ p ,…
Abstract In agreement with the aromaticity and electrophilic behavior of squaric acid, a cyclobutenediyliumtetroxide ion is formulated as a limiting form of the squarate dianion. These views are confirmed by the structure of a series of new compounds that are readily obtainable from squaric acid or its derivatives, an…
The ir reflection spectrum of single-crystal stannic oxide has been observed at room temperature in the region 2000 to 100 cm−1, and analyzed by classical dispersion theory to give values for the transverse and longitudinal optical-mode frequencies. For the cassiterite structure, four lattice-vibration modes may inter…
Abstract The dielectric properties and the d. c. conductivity of poly(vinyl chloride), poly(vinyl acetate), polychlorotrifluoroethylene, and poly(ethylene terephthalate) were measured at temperatures above and below the glass transition temperature and at various pressures up to 3000 atm. The α relaxation associated w…
Single crystals of MnSb with various Mn compositions in ε phase were prepared successfully with Bridgeman method. Magnetization and torque measurements were made on these crystals in temperatures ranging from 4.2°K to 800°K. The temperature dependence of saturation magnetization on the sample with 48.2 at. % Mn was in…
A new electro-optic effect based on the disruptive effects of ion transport through certain classes of nematic liquid crystals is presented. The initially transparent liquid scatters light strongly (appears white) when subjected to fields of 5 × 103 V/cm. Reflective contrast ratios of better than 20:1 with efficiencie…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTemperature dependence of photoisomerization. V. Effect of substituents on the photoisomerization of stilbenes and azobenzenesDina Gegiou, K. A. Muszkat, and Ernst FischerCite this: J. Am. Chem. Soc. 1968, 90, 15, 3907–3918Publication Date (Print):July 1, 1968Publication His…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectronic structures of hexacyanometalate complexesJohn J. Alexander and Harry B. GrayCite this: J. Am. Chem. Soc. 1968, 90, 16, 4260–4271Publication Date (Print):July 1, 1968Publication History Published online1 May 2002Published inissue 1 July 1968https://pubs.acs.org/doi…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetic analysis of thermogravimetric dataJ. ZsakoCite this: J. Phys. Chem. 1968, 72, 7, 2406–2411Publication Date (Print):July 1, 1968Publication History Published online1 May 2002Published inissue 1 July 1968https://pubs.acs.org/doi/10.1021/j100853a022https://doi.org/10.10…