Materials Literature
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The rate of growth of slightly soluble ionic precipitates from aqueous solution is affected by the presence of a co-ordinated layer of water molecules clustered around a central ion. When the ions are small and highly charged, water molecules in the cluster are firmly held; in such solutions it is known that ion assoc…
Abstract Polystyrenes containing end groups derived from azobisisobutyronitrile (AIBN) were subjected to thermal degradation at 280–350°C and the rates of volatilization compared with those of thermally and anionically prepared polystyrene. At 330–350°C the degradation of the AIBN polymer resembled that of the thermal…
Abstract In the thermal oxidation of low density polyethylene (PE) in the melt phase and isotactic polypropylene (PP) in the solid phase, the changes in molecular weight distribution (MWD), weight average molecular weights ( M ω), and average number of chain scissions have been studied by gel permeation chromatography…
Two homologous series of liquid crystalline substances have been synthesized and their mesomorphic properties studied. These are (i) trans-p-n-alkoxy-α-methyl cinnamic acids and (ii) trans-p-n-alkoxy-α-methyl-p'-cyanophenyl cinnamates. The esters are colourless and fairly low melting materials of high positive dielect…
The ferroelectric-paraelectric phase transition in PbZrxTi1-xO3 (0.88 < x < 1) has been investigated using x-ray, dielectric and optical techniques. It is shown that a changeover from first-order to second-order behaviour occurs at around x = 0.94. The exponent, β, of the order parameter in the region of this critical…
It has been shown previously that in analogy with the Borrmann effect in X-ray diffraction from crystals there is an anomalous increase in the transmitted intensity near the Bragg reflection band in an absorbing cholesteric liquid crystal. In this communication detailed experimental studies of this effect carried out…
Textural laser diffraction and light-scattering studies on homeotropically aligned nematic material (MBBA) doped with cholesteryl nonanoate (CN) has been carried out with and without an applied ac (50 Hz) electric field. In the narrow range of the ratio of the pitch p to the thickness l of the cell, 1.2&lt;p/l&…
Article A New Class of Polyethers-Poly(1,4-Dichloro-2,3-Epoxybutane)s - Synthesis, Mechanism and Property Aspects was published on January 1, 1976 in the journal Pure and Applied Chemistry (volume 48, issue 3).
Abstract A series of fluorene and fluorenone diamines were polymerized with two aromatic dianhydrides, and the resulting polyamic acids were cyclodehydrated to aromatic polyimides. A study of the mechanical properties of the polyimide films disclosed they are among the stiffest reported to date, with an excellent rete…
Crystals of K2S5 are orthorhombic, space group P212121 with Z= 4 in a unit cell of dimensions: a= 6.494(1), b= 6.600(2), c= 17.414(5)Å. The structure has been elucidated by vector methods from 656 independent diffracted intensities measured on a four-circle diffractometer and refined to R 0.045. The [S5]2– anion exist…
Abstract The disproportionation of thiosulfate, trithionate, tetrathionate and sulfite in acidic solutions has been studied at relatively high temperatures. Thiosulfate hardly decomposes in the absence of sulfuric acid, even at 150 °C, but decomposes very easily in the presence of sulfuric acid at 70 °C, forming eleme…
The phase diagrams for the mixtures of p-cyanophenyl-p-alkylbenzoates and p-alkoxycarbonyl-oxyphenyl p-butyloxybenzoates were investigated. The Schröder-Van Laar equation was found inapplicable for calculations of composition, eutectic-mixture melting points and crystalline-nematic transition heats of these compounds.
This series was organized to provide a forum for review papers in the area of corrosion. The aim of these reviews is to bring certain areas of corrosion science and technology into a sharp focus. The
The subsolidus compatibility relations in the system SrO‐B 2 O 3 ‐ SiO 2 were determined by solid‐state reaction techniques and X‐ray powder diffraction methods. The system was found to contain 11 subsolidus compatibility relations, one stable ternary compound (Sr 3 B 2 SiO 8 ), and one metastable ternary compound wit…
Organized bone ingrowth in endosteal porous implants fabricated from VMC titanium alloy and surgically implanted with a tight interference fit, securely anchored the implants in fresh and healed mandibular premolar sites of miniature swine. This bone-implant union retained its integrity under high as well as slight ma…
Experimental results are presented for the thermal conductivity of P-doped Si over the concentration range 2.5 x 10^14 to 1.1 × 10^18 cm-3 in the temperature region 1.5-50 K. In the low concentration range, phonon scattering by isolated P donors is very weak in contrast with that by Group-V donors in Ge and Li donor i…
When human subjects are irradiated with pulse modulated microwave energy they report the perception of a sound that appears to originate from within or slightly behing the head. Three of the possible mechanisms are examined using first order mathematical approximations and several simplifying assumptions. The results…
This research explores the basic hypothesis that microporosity may play a significant role in the mechanism of breakdown of XLPE cable. The potential improvement achieved by impregnating the cable core with a neutral liquid is evaluated, in relation to ac voltage life and impulse strength. The effect at higher frequen…
The structure and dynamics of “graphon”, a carbon black, have been characterised by a combination of neutron diffraction and inelastic scattering experiments. The techniques employed were those of neutron diffraction, time-of-flight and beryllium-filter spectroscopy.The dimensions of the unit cell were found to be: a=…
The three independent components of the second order Raman spectra of SrTiO3 have been measured at 300 K. They show a strong similarity to the second order spectra of SrO. Very recently, the lattice dynamics1 and the Raman spectra of SrO have been successfully explained on the basis of a nonlinear shell model. It is s…