Materials Literature
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Abstract Stretched films from partly unsaturated natural rubber hydrochloride develop cracks and fracture in ozonized oxygen. Cracking occurs only above a minimum stress level of about 70 kg./cm. 2 . Ozone sensitivity increases exponentially with stress, but goes through a maximum near the yield point of the thermopla…
Abstract The dynamic shear modulus at very high strains, ( G ∞ ), of carbon black filler loaded vulcanizates is regarded as due to the product of two factors : ( a ) a hydrodynamic interaction due to filler particles, and ( b ) a second factor for which evidence is given suggesting that it arises from a few strong lin…
The heat content of uranium dicarbide was measured from 1484° to 2581°K using a drop calorimeter.
Abstract The degradation of a polycarbonate by electron irradiation in oxygen and in vacuum has been examined. It was found that the polymer undergoes chain scission and that crosslinking apparently did not occur, the molecular weights of irradiated specimens were therefore determined from the intrinsic viscosity of m…
The optical constants of liquid tellurium at 500 and 600°C have been measured by a reflection method in the spectral range 4000 to 23 000 cm−1 (2•5 to 0•43 microns). The conductivity σ(k) for wave number k is considered as the sum of two terms, σc(k) due to intra-band transitions and σv(k) due to inter-band transition…
Abstract Bei der thermogravimetrischen Zersetzung von Praseodymchromat(VI) geben die Abbaukurven keine Hinweise für die intermediäre Bildung von Praseodymchromat(V). Trotzdem konnte durch analytische und röntgenographische Untersuchung partiell abgebauter Pr 2 (CrO 4 ) 3 ‐Präparate die Existenz des thermisch sehr inst…
In order to obtain some information about the effective electron number of nitrogen in ${\mathrm{Mn}}_{4}$N, the x-ray atomic scattering factors of nitrogen and manganese were measured by Fe $K\ensuremath{\alpha}$ radiation. The experimental values of the scattering factor of nitrogen determined within a resultant pro…
Abstract The kinetics of polymerization of butadiene and isoprene with butyllithium initiator have been studied both in n ‐hexane and tetrahydrofuran solution. The overall polymerization rates were much faster in the THF solutions than in n ‐hexane, and the latter also exhibited relatively slow initiation rates compar…
Abstract Column leaching experiments with 0.001 N CsCl with 1 N KCl or CaCl 2 showed Cs sorption by a number of clays to be much larger from Ca than from K solutions. The sorption affinity of Cs relative to the complementary ion corresponded with that found by others for the Cs‐K ion pair, but in Cs‐Ca systems the Cs…
The growth of germanium dendrites containing two twin planes has been investigated. The solution of the heat flow problem in the stem of a growing dendrite being pulled from a melt permitted the design of experiments suitable for testing theory. The limiting growth velocity was determined as a function of melt underco…
A technique is described for testing rutile single crystals in compression at elevated temperatures. The stress‐strain behavior of crystals of four different orientations was examined up to temperatures in excess of 1000°C, and a dependence of both the flow stress and the rate of work hardening on crystal orientation…
Nuclei of several isotopes of promethium were aligned at low temperatures by a pseudoquadrupole interaction in cerium magnesium nitrate and by a magnetic hfs interaction in neodymium ethylsulfate. Pseudoquadrupole coupling constants were determined for ${\mathrm{Pm}}^{143}$, ${\mathrm{Pm}}^{144}$, and 5.4-day ${\mathr…
Abstract The structure of hexagonal polyoxymethylene has been re‐examined by means of x‐rays. The parameters of the elementary cell, the space groups, and the model of the spiral chain previously described in the literature for this polymer have been discussed. A new elementary cell and a new type of helical chain wit…
Abstract The steady‐state (d.c.) electrical conductivity of polypropylene has been measured as a function of temperature (25–150°C.) and field strength (0–94 kv./cm.). The temperature coefficient of the conductivity is 34.6 kcal./mole expressed as an activation energy. This is much larger than the activation energy fo…
Ac electrical conductivity measurements have been made on polycrystalline samples of various compositions in the MgO–NiO system. Four activation energies have been obtained with pure MgO: 5.2, 2.7, 3.5, and 0.92 eV. These seem to be the activation energies, respectively, for intrinsic O= conductivity, extrinsic O= con…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCarbon-13 Nuclear Magnetic Resonance Spectra of Olefins and Other HydrocarbonsR. A. Friedel and H. L. RetcofskyCite this: J. Am. Chem. Soc. 1963, 85, 9, 1300–1306Publication Date (Print):May 1, 1963Publication History Published online1 May 2002Published inissue 1 May 1963htt…
Randomly oriented fibers of either molybdenum or niobium were incorporated into hot‐pressed pellets of 10, 30, and 50 wt% UO 2 in ThO 2 to improve the thermal conductivity and the thermalshock resistance. Pellets 3/8 in. in diameter and about 3/8 in. long were irradiated in NaK capsules either bare or jacketed in Zirc…
SUMMARY Vitamin B12 is an essential nutrient for the flagellate Prymnesium parvum when growing in axenic culture and apparently can be replaced only by a few related ‘incomplete’ analogues, i.e. only those devoid of one or both benzimidazole-methyl groups; and, of the substituted analogues, some (e.g. the mono-acid, t…
Abstract The dynamic properties of a natural vulcanized rubber containing carbon black were studied for dynamic tensions of amplitude varying greatly. It was shown that both the elastic responses and viscosity change with amplitude of oscillation and with concentration and type of carbon black. The effects of thermal…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Structure of Copper TetraphenylporphineEverly B. FleischerCite this: J. Am. Chem. Soc. 1963, 85, 9, 1353–1354Publication Date (Print):May 1, 1963Publication History Published online1 May 2002Published inissue 1 May 1963https://pubs.acs.org/doi/10.1021/ja00892a032https://…