Materials Literature
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Abstract Dilatométric studies on five PMM samples of different tacticities show generally three transition ranges between −35 and 150°C. The main glass transition temperature depends on the relative proportion of the iso‐ or syndiotactic segments. The secondary transition, located around 60°C., seems to be related to…
Abstract A 12×12 representation is given of the valence band Hamiltonian at k = 0 which includes the spin‐orbit interaction. Expressions are derived for the energies and the linear combinations of the wave functions for the Γ 7 , Γ 8 , and Γ 9 subbands. The whole valence band is completely determined by eight paramete…
The addition of tributyltin methoxide and of biotributyltin oxide to the following acceptor molecules is described : isothiocyanates, trichloroacetonitrile, carbon disulphide, carbon dioxide, sulphur dioxide, and carbodi-imides. The corresponding phenoxide is generally less reactive than the methoxide. The initial pro…
The oligomerization of substituted phenyl glycidyl ethers was studied kinetically in the presence of dimethylbenzylamine using toluene or dioxane as a solvent. The infrared spectra of the resultant oligomers suggest that the reaction products have the internal carbon-carbon double-bond un-saturation, which is confirme…
The addition of halide ions causes an increase in the observed bimolecular rate constant k0 for the Fe(II)+H2O2 reaction, ultimately reaching a limiting value depending on the anion. This is interpreted in terms of complex formation between ferrous ions and halide ions, with the complex reacting faster than the hexa-a…
Abstract Density, morphology, and melting data on linear polyethylene and high molecular weight polymethylene crystallized from the melt under elevated pressure are presented. For approximately constant supercooling a sharp density increase is noted above 2300 atm. crystallization pressure. Above 4000 atm. densities a…
Activation of rare earth vanadate by ions other than rare earths is successfully attempted in the present investigation. Bi +3 can be incorporated in the and lattice by solid‐state reaction. The phosphor , excited by cathode rays or uv radiation, shows luminescence with a continuous emission band extending from 4000 t…
New data have been used in a refinement which leads to molecular dimensions P-O (bridge) 1.612+ 0.005 A, P-O (outer) 1.
Abstract By using the method of free torsion vibrations, a detailed dependence was determined of the temperature position and the height of the secondary (β) loss maximum of alkali‐polymerized polycaprolactam upon the concentration of water in the range of 0 < P A < 1.3, where P A is the number of moles of water…
Manganese‐activated phosphors were prepared by solid state reactions throughout the spinel crystalline solution region in the system. The best ultraviolet‐excited phosphor examined, , is characterized by a peak emission wavelength at 512 ran, a 50% peak intensity band width of 36 nm, and a quantum efficiency equivalen…
By using a high‐speed technique described in ref. (1), anodic (aluminum dissolution) polarization data have been obtained for aluminum surfaces free from oxide films and from the normal concurrent hydrogen evolution. Similarly cathodic (hydrogen evolution) polarization data have been produced for oxide‐free aluminum s…
Vibrational spectra of the following ions are reported: InCl63–, TlCl63–, PbCl64–, SbCl63–, BiCl63–, SeCl62–, TeCl62–, SbCl52–. It is suggested that ν3 for the octahedral “inert pair ions” may be anomalously broad. In species such as Cs2SbCl6 the presence of SbIII and SbV is observed and the relative intensities of th…
Abstract Polyethylene networks were prepared by γ‐irradiation of linear polyethylene, both molten and crystalline. The elastic and photoelastic properties of the networks were studied at high temperatures, i.e., in the molten state. The equilibrium swelling was also measured in several solvents. Values of the crosslin…
The cathodoluminescence from Eu 3+ and Tb 3+ in the orthoborates of In, Sc, Y, La, Gd, and Lu is examined. The host is shown to be particularly effective for both activators. Observed spectral details of the luminescence are related to effects of crystal symmetry on electronic transitions.
The equilibrium oxygen pressure for the reaction was accurately measured over the temperature range 910°–1145°K. The following working equation for the oxygen pressure is valid over the experimental range. The following expressions, valid from 298°–1200°K, apply to the formation of one mole of The heat of formation an…
Infrared and Raman spectra are reported for tin(IV) nitrate, titanium(IV) nitrate, and vanadium(V) oxide trinitrate. The spectra are consistent with bidentate co-ordination of all nitrato-groups in each case and assignments are suggested for the bands on this basis. Coupling of the vibrations of individual nitrato-gro…
Introduction. The distribution of stress produced in the interior of an infinite elastic solid when a constant pressure is applied over the entire surface of a penny-shaped crack has been solved by Sneddon(6), (7). The problem considered here is the closely allied one of a plane longitudinal wave, harmonic in time, mo…
Abstract The values of Δε and σ 0 in the expression σ = σ 0 exp {−Δε/ 2kT } for the dark conductivity σ, tend to increase together over the whole range of organic semiconductors. They fall into a broad band of values confined roughly between two lines given by log σ 0 = αΔε + β, the compensation rule, with log σ 0 var…
Abstract Studies of single‐crystal deformation explain the small‐ and wide‐angle x‐ray observations of the cold drawing of PE, particularly the effects in the necking zone where the original spherulitic structure is transformed into a highly aligned fiber structure. Whole blocks of folded chains are broken out of the…
Abstract The crystallization kinetics and morphology of poly(tetramethyl‐ p ‐silphenylene)siloxane spherulites have been investigated over a temperature range of 25–130°C. The effect of molecular weight on the spherulitic growth rates, ranging from the monomer to molecular weights about 10 6 , is discussed in terms of…