Materials Literature
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Abstract New series of diamines having pyridine rings and o ‐, m ‐, or p ‐phenylenedioxy linkages were prepared by condensation of chloronitropyridine with isomeric dihydroxybenzenes followed by chemical reduction. The polymerization of the diamines with benzo‐phenonetetracarboxylic acid dianhydride gave polyamic acid…
Abstract Aromatic benzimidazole polymers have been prepared by reaction of the corresponding tetraamine and diester in refluxing sulfolane or phenyl sulfone. The convenience of using these sulfone solvents together with the good yields, high viscosities and absence of crosslinking make this procedure an attractive new…
Abstract Creep tests at constant values of tensile stress, temperature, and relative humidity for two thermoplastics were conducted for approximately 132,000 hr. The strains, ϵ, for the first 2000 hr of time, t , were described by an equation of the form ϵ = ϵ o + ϵ + t n where all other symbols are constants. This eq…
A quantitative analysis of the effect of spin lattice relaxation rates on pure quadrupole resonance pulse experiments for spins with I = 1 is given. A model is presented in which the three dimensional relaxation problem is reduced to a two dimensional one. In this model any possible population distribution of the ener…
The effect of the magnetic transition on the optical-absorption edge has been studied for three antiferromagnetic crystals, MnO, $\ensuremath{\alpha}\ensuremath{-}\mathrm{MnS}$, and CoO. MnO shows a red shift, whereas $\ensuremath{\alpha}\ensuremath{-}\mathrm{MnS}$ and CoO show a blue shift. The observations can be sa…
Flat surfaces of MgO and KCl crystals and teflon sheet were coated with gold evaporated films except for the parallel strip areas approximately 200, 100 and 50 µm wide, and the strip areas without coating were observed by SEM at 15 kV. The images of the uncoated areas were distorted by the surface potential caused by…
Abstract When isotactic polystyrene (i‐PS) is crystallized from the melt or from the glassy state at rather large supercooling an additional melting peak appears on the curve during scanning in a differential calorimeter. The overall rate of crystallization deduced from the total peak areas as a function of crystalliz…
Abstract A new technique was developed to study the molecular mechanics of highly oriented polypropylene during stress relaxation and creep. The polarized infrared spectrum was recorded while the polymer was under load. Stress relaxation effects were investigated during the two‐stage process of fast decay followed by…
The theory of the holographic grating is applied to the design of aberration-corrected holographic concave gratings for use with Seya–Namioka monochromators. A method of determining the proper recording parameters is described. The performance of gratings that would be produced by use of the proper recording parameter…
The bulk magnetic susceptibilities of several synthetic polypeptides have been measured. The observed anisotropy of the diamagnetic susceptibility Δχ for oriented nematic liquid crystals of poly-γ-benzyl-L-glutamate (PBLG) in dichloromethane is 7.0±0.7×10−6 emu/mole. For a PBLG axial ratio of 150, a value of the twist…
Optical-reflection spectra have been measured for hexagonal NiS in the energy range 0.01 - 5.0 eV at temperatures both above and below the metal-nonmetal transition near 260 K. Using Kramers-Kronig analysis it is found that the conductivity below 0.1 eV drops on cooling through the transition. Above this energy a peak…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReversible reaction of simple ferrous porphyrins with molecular oxygen at low temperaturesDavid L. Anderson, Charles J. Weschler, and Fred BasoloCite this: J. Am. Chem. Soc. 1974, 96, 17, 5599–5600Publication Date (Print):August 1, 1974Publication History Published online1 M…
The design features of an efficient geometric backscattered electron detector are presented. This detector appears to have approximately the same limit of spatial detectability as a secondary electron detector. It has the advantages over a secondary electron detector of a reduction of charging artefacts, improved flat…
A method of tracing rays through holographic gratings, both plane and concave, is developed. The method is applicable not only to holographic gratings, but also to mechanically ruled gratings with variable spacing and curved grooves. Some examples are given in the form of spot diagrams for certain specific cases. A mo…
Superposition of illumination with white light on thermal treatments of amorphous films, formed by deposition of high-purity Se on mica, had the following effects on crystallization: (i) interface cylindrites thickened much more rapidly but their radial growth rates were not detectably changed; (ii) the number density…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCrystal structure of sodium gold(I) thiosulfate dihydrate, Na3Au(S2O3)2.2H2OHelena. Ruben, Allan. Zalkin, Marjorie O. Faltens, and David H. TempletonCite this: Inorg. Chem. 1974, 13, 8, 1836–1839Publication Date (Print):August 1, 1974Publication History Published online1 May…
By empirical methods similar to those outlined previously for the iron garnets, molecular-field coefficients are reported for the complicated LiTiZn ferrite system. As in the case of the garnets, the intrasublattice coefficients NAA and NBB are linearly dependent on the Ti4+ and Zn2+ concentrations, but the intersubla…
The crystal structures of 4 ammonium exchanged, heat-treated faujasites were determined from x-ray powder data. Structure I, often called "decationated Y," has lost 15 framework aluminum atoms and 21 framework O (1) atoms (bridging oxygen atoms) per unit cell, and 15 Al(OH) 2 + ions are present in the sodalite cages.…
This paper reports a new phenomenological observation regarding the stress crazing of glassy polystyrene. It was found that the applied stress to initiate a craze, often called the critical crazing stress, is independent of molecular weight. Further, the gross structure of the craze does depend on molecular weight, an…
We present dc measurements of the reversible pyroelectric effect in the temperature interval 170–350 °K and of the inverse piezoelectric effect at 0.3 °K for films of commercial polyvinylidene fluoride which were polarized in a strong dc electric field at elevated temperatures. The pyroelectric coefficient dP/dT incre…