Materials Literature
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Abstract Uncertainty as to the nature of the crosslinks in vulcanized rubber has been a tremendous handicap to chemical studies of vulcanization. A direct result is that physical methods have been the most successful in providing definite information about the nature of vulcanized rubber. However, these physical metho…
The spin-spin interaction via phonon exchange is proposed as a new mechanism of the so-called exchange interaction between the electron spins of the paramagnetic ions in crystal which has been overlooked hitherto. The interaction Hamiltonian derived by Van Vleck to account for the spin-lattice relaxation phenomenon is…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCopper Phthalocyanine Polymers1William C. Drinkard and John C. Bailar Jr.Cite this: J. Am. Chem. Soc. 1959, 81, 18, 4795–4797Publication Date (Print):September 1, 1959Publication History Published online1 May 2002Published inissue 1 September 1959https://pubs.acs.org/doi/10.…
The indirect-exchange mechanisms which produce spontaneous magnetization in metal oxides are an optimum if two interacting cations are located on opposite sides of an anion. The coupling rules which have been developed for this case are not applicable to spinels in which the cation-anion-cation angles differ appreciab…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCation Substitution in Perovskite-like Phases1,2E. J. Fresia, Lewis Katz, and Roland WardCite this: J. Am. Chem. Soc. 1959, 81, 18, 4783–4785Publication Date (Print):September 1, 1959Publication History Published online1 May 2002Published inissue 1 September 1959https://pubs…
Abstract Some general rules regarding the conformation and mode of packing of macromolecular chains in crystals are illustrated. The monomeric units occupy equivalent positions in regard to the axis of the chain. It follows that crystallizable polymers must have a type of regularity which will enable them to assume th…
Measurements of the density of a large number of experimental isotactic polypropylenes have shown that the specific volume is linearly related to per cent crystallinity as determined from x-ray data. The density is also linearly related to the absorbance of certain absorption bands in the infrared spectrum of isotacti…
The phase equilibrium relations in the systems Y 2 O 3 ‐Al 2 O 3 and Gd 2 O 3 ‐Fe 2 O 3 were examined. Each system has two stable binary compounds. A 3:s molar ratio garnet‐type compound exists in both systems. The 1:1 distorted perovskite structure is stable in the system Gd 2 O 3 ‐Fe 2 O 3 but only metastable in the…
Abstract This review has attempted to categorize and describe the degree of ozone resistance available both within and among the various elastomers. Some of the factors affecting ozone resistance and means for obtaining ozone-resistant vulcanizates have been discussed. It has been indicated that by judicious selection…
Intermittent and continuous stress relaxation measurements have been utilized to follow the oxidative degradation of vulcanizates of natural rubber, and of synthetically prepared polybutadienes. Vulcanizates were prepared by exposing samples to high-energy electrons. For natural rubber, only oxidative scission reactio…
Lattice parameter‐composition relations are shown in the system α‐Fe 2 O 3 ‐Cr 2 O 3 . This information is of some value in determining the composition of scales developed during the oxidation of alloys based on Fe‐Cr, such as stainless steels.
An x-ray diffraction method is described for the determination of per cent crystallinity in oriented films and fibers of polyethylene terephthalate by using an x-ray diffractometer in association with a scaler counter. Results are presented to show that sample rotation approximately averages out the crystallite orient…
Abstract Mechanical properties and melt viscosity have been measured on anionc polystyrene of narrow molecular weight distribution and thermal polystyrene of broad molecular weight distribution in an attempt to study the effect of molecular weight distribution. Tensile strength and elongation were found to depend upon…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCHARGE TRANSFER LUMINESCENCE OF A RUTHENIUM(II) CHELATEJ. P. Paris and Warren W. BrandtCite this: J. Am. Chem. Soc. 1959, 81, 18, 5001–5002Publication Date (Print):September 1, 1959Publication History Published online1 May 2002Published inissue 1 September 1959https://pubs.a…
We use a model for ferromagnets such that the electrical current is carried by 4s (or 6s) electrons which are assumed to be described in band scheme and the unpaired electrons (3d or 4f) are assumed to be localized on the lattice points. In the temperature region far below the Curie point the spin-disorder in spin ori…
Abstract The nature of banded spherulites was further investigated. The principal material used was a polyester, namely, polytrimethylene glutarate, but use was made also of nonpolymeric materials. A variety of observations on extinction effects with the Universal Stage conclusively confirmed the twisted crystal model…
The resistivity of barium titanate which is usually of the order of 10 9 ∼10 12 ohm-cm, may be remarkably reduced with suitable control in valency. The valency-controlled barium titanate, whose resistivity is of the order of 10∼10 4 ohm-cm at room temperature, shows anomalous positive character in the temperature depe…
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A special technique for the accurate measurement of thermal conductivity is discussed. The method involves use of the Peltier heat to maintain a temperature gradient along the specimen. Straightforward measurements allow calculation of the absolute value of the thermoelectric power, thermal conductivity, and electrica…
Abstract The infrared spectrum of uniplanarly oriented valonia cellulose film and the polarized infrared spectra of doubly oriented films of ramie and bacterial cellulose crystallites have been observed in the region from 640 to 1700 cm. −1 . The spectra have been interpreted with the assistance of band assignments in…