Materials Literature
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Abstract Dilatometric measurements show that both isotactic and atactic polypropylenes have two distinct glass transition temperatures. Because of the two transitions, three values for the cubical coefficient of thermal expansion are necessary to accurately define the volume expansion of polypropylene from −80° to +90…
Abstract The Monte Carlo sampling technique was used to evaluate the resulting molecular weight averages and the intrinsic viscosity for wide Schulz‐Zimm distribution polymers, in the range P̄ w /P̄ n ≦ 11, undergoing random chain scission and crosslinking processes. The results may also be used to evaluate the initia…
Scoured cotton yarns were acetylated by two processes: (1) by a 1:3 mixture of acetic anhydride and acetic acid to give a series of low- and medium-substituted products (PA); and (2) a 1:1 mixture of acetic anhydride and isopropyl acetate to give a series of medium- to highly-substituted products (FA). Perchloric acid…
Calculations have been made for the color and luminous efficiency of single phosphors and of blends of such phosphors. In the latter case, all the emission is assumed to come from the phosphors so that the results apply to cathode-ray tubes or to electroluminescent lamps, but not to fluorescent lamps. In these calcula…
Received 3 September 1963DOI:https://doi.org/10.1103/PhysRevLett.11.331©1963 American Physical Society
In x-ray microanalysis allowance must be made not only for absorption of x-rays but also for the effects of penetration, diffusion and backscattering of the incident electrons. In view of the impossibility of pursuing separately every electron path, a simplified diffusion model is proposed and calculations based on th…
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 Erhard J. Schimitschek; STIMULATED EMISSION IN RARE‐EARTH CHELATE (EUROPIUM BENZOYLACETONATE) IN…
The preparation of acidodiethylenetriaminegold (III) salts with the general formula (Au(dien)X) X2 (dien NH2C2H4NHC2H4NH2 and X Cl(-), Br(-) is reported. The complexes are acids in aqueous solution, ionizing a proton from one of the amine nitrogen atoms. The resulting con jugate bases, (Au(dien-H)X) X (dien-H) dien le…
Stress-corrosion cracking facts and theories are reviewed, especially the phenomena found with stainless steels and with α-brass. Evidence is given that stress-corrosion "cracking" is not rupture of brittle metal. Rather, cracks propagate by rapid dissolution of their mechanically yielding advancing edges, while their…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAn LCAO-MO-Study of Static Distortions of Transition Metal ComplexesL. L. Lohr Jr. and William N. LipscombCite this: Inorg. Chem. 1963, 2, 5, 911–917Publication Date (Print):October 1, 1963Publication History Published online1 May 2002Published inissue 1 October 1963https://…
The polarized vibronic spectra of PrCl3 and PrBr3, as well as Pr3+ in LaCl3 and LaBr3, were observed. The theory of vibronic transitions for the dilute salt is shown to predict a spectrum which closely resembles the vibronic spectrum of the pure salt, in agreement with experiment. Approximations valid when the optical…
By special light optical observation techniques monolayer polyethylene single crystals could be examined in their uncollapsed configuration while still in suspension and related to their fully or partially collapsed forms seen electron-microscopically. The existence of the previously deduced non-flat based hollow pyra…
The obliquity of the fold surfaces of monolayer polyethylene crystals was investigated quantitatively. Two crystal types were used: (a) true lozenges formed at 76°c (high supercooling) previously observed as corrugated; (b) truncated lozenges formed at 90°c (low supercooling) previously observed as hollow pyramidal. Q…
SYNOPSIS After some general remarks concerning the interpretation of certain structural markings of Mastogloia , which have hitherto often been neglected, but which must now be considered as being of value in separating otherwise similar species, some new Mastogloia are described, in the first part from collections ma…
A previously derived theory of equilibrium polymerization is generalized to take into account the effect of superposed hydrostatic pressure, and the results are applied to the equilibrium polymerization of sulfur. It is shown that the transition which at atmospheric pressure occurs at about 160°C is shifted with press…
Abstract— Ultra‐violet irradiation of deoxygenated solutions of anthracene, tetracene or pentacene causes the disappearance of the polyacene absorption spectrum and the appearance of an absorption spectrum which is attributed to the photo‐dimer of the polyacene. Molecular structures for ditetracene and dipentacene are…
It has been tried to classify newly discovered ferroelectrics as well as old ones according to their Curie-Weiss constants. Results have suggested that the displacive type ferroelectrics are not necessarily oxide crystals, and have also shown that small Curie-Weiss constants are not very rare in new ferroelectrics. Cl…
Pressure sintering (or hot‐pressing) of pure alumina and magnesia in graphite dies and in ceramic dies over the range 1100° to 1700°C and 4000 to 10,000 psi has been shown to be very useful in fabricating these materials with controlled microstructures (e.g., very high relative density and fine grain size or controlle…
The transmission and reflection spectra of cuprous oxide have been measured from 2 to 25 μ. The transmission studies included Cu2O18. The isotope shifts help to establish that all the observed infrared bands are due to lattice vibrations and not to defect mechanisms as some authors have suggested. The reflectivity can…
Triplet energy migration and triplet-triplet annihilation leading to fluorescence radiation are discussed. The molecular crystals considered are arthracene and naphthalene. Conclusions concerning the mechanism of the triplettriplet annihilation, the recombination of the ion pair, and the rate- determining step in the…