Materials Literature
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The high specific conductivity of graphite fiber/copper matrix (Gr/Cu) composites offers great potential for high heat flux structures operating at elevated temperatures. To determine the feasibility of applying Gr/Cu composites to high heat flux structures, composite plates were fabricated using unidirectional and cr…
By using dielectric relaxation spectroscopy it has been observed that while the molecular reorientation around the long axis in the smectic B-crystal phase is active, the rotation around the short axis is frozen. Thus we show that the molecular dynamics of the liquid crystal phase designated as smectic B-crystal is in…
Abstract Stress‐relaxation behavior is studied in polypropylene samples subjected to different cyclic preloadings and to simple tension. The relaxation tests are performed under different sets of strain amplitude, number of cycles, and strain rate, using a closed‐loop, electrohydraulic, servocontrolled testing machine…
The growth of crack-free 3-inch-diameter lithium tetraborate ( Li 2 B 4 O 7 ) single crystals by the Czochralski method has been studied. The relationships between crystal cracking rate during growth and the crystal rotation rate and the position of the work-coil have been examined. It is concluded that crystal cracki…
The influence of miscibility of an acrylic PSA and several tackifier resin systems upon PSA performance was investigated. When the acrylic copolymer and the resins were blended in various proportions, three types of mixing state were found: miscible system, partially miscible system and immiscible system. In the case…
The crystal structure of a new compound Li 2 Mg 2 (WO 4 ) 3 has been determined by means of X-ray powder diffraction. Li 2 Mg 2 (WO 4 ) 3 belongs to the orthorhombic system, with space group Pnma and the lattice parameters are: a = 5.1129 Å, b = 10.462 A, and c = 17.612 Å at room.temperature. Its measured density is D…
Abstract The easily accessible, water soluble, conjugated polymer poly(4‐bromopyridine), has been synthesised by the self‐condensation of 4‐bromopyridine at various temperatures and also in the presence of methyl iodide. The structure of the material is complex with a variety of sub‐units; possible structures are disc…
Measurements of the rate of crack growth in alloy 600 (UNS N06600) in high-temperature lithiated hydrogenated water were performed at various potentials and pH levels. The mode of cracking was found to be dependent on temperature and pH of the solution. The lowest crack growth rate occurred from pH 6 to 7. Intergranul…
In this paper the scalar quasi-static magnetic hysteresis is described by means of a new model based on a sequential algorithm, which appears to he a possible alternative to the classical Preisach model. A procedure leading to the identification of the model parameters is described. The hysteretic behavior obtained by…
Abstract The electrical and optical properties of 1,4‐ cis ‐polyisoprene before and after doping with SnCl 4 and SbCl 5 were investigated. The material becomes reddish brown and black upon doping with SnCl 4 and SbCl 5 , respectively, and the conductivity increases by about 11 orders of magnitude. The optical absorpti…
Abstract This article deals with the microlevel structure of the electronically conductive polymer, polyaniline, on the basis of the conducting islands model of Epstein et al. The paper presents, for the first time, TEM pictures of the microlevel structure of heavily doped polyaniline, possibly showing the conducting…
Ferricytochromes c were crystallized at low ionic strength by macroseeding techniques. Large crystals were grown by seed-induced self-nucleation which occurred anywhere in the drop, regardless of the location of the seed crystal. This unusual crystal-seeding method worked reproducibly in our hands, and X-ray quality c…
Abstract The interrelationship between the cross‐linking and isoimide‐imide isomerization reactions of oligomeric isoimides and imides was investigated using FTIR spectroscopy. It was found that cross‐linking of the acetylene units of Thermid IP‐600 retarded the local rearrangement of the isoimide to imide conversion…
The effect of hydrostatic pressure on the structural phase transitions has been studied for the tetraethylammonium tetrahalogenometallic compounds, {N(C2H5)4}2-XY4 (XY4 = ZnCl4, ZnBr4, CoCl4, CoBr4, MnBr4, and CuBr4) by dielectric measurements. The transition temperatures increase linearly with increasing pressure. Th…
X-ray scattering measurements have been carried out for free-standing, thick monodomain films of the orthogonal hexatic-B phase. From Fourier analysis of χ-scans, 6 n -fold-symmetry order parameters were determined and proved to fulfill the scaling relation C 6 n = C 6 n +λ n ( n -1) . The temperature behavior of C 6…
Blends of uncrosslinked styrene-butadiene rubber (SBR) with a terpene tackifier resin or a naphthenic oil have been characterized, and their autohesion and cohesion determined using a T-peel geometry. SBR/oil blends are homogeneous at all proportions, while SBR/resin blends, based on DSC and DMA analysis, undergo bulk…
Abstract Approaches to plastics recycling mainly include direct recovery keeping the polymer structure intact, depolymerization and then reuse of monomers, and methods involving reduction of polymer to gases and low molecular weight oils. The model process presented here belongs to the first category: It is proposed d…
Résumé: Nous analysons la déformation de cisaillement pour différentes vitesses de chargement dans le domaine des grandes et très grandes vitesses de déformation. Ainsi, nous présentons brièvement les différentes techniques expérimentales utilisées dans ce domaine. Une nouvelle technique expérimentale basée sur l&…
There is an increasing challenge for chemical industry and research institutions to find cost-efficient and environmentally sound methods of converting natural resources into fuels chemicals and energy. Catalysts are essential to these processes and the Catalysis Specialist Periodical Report series serves to highlight…
The transition behaviour of deformation mode from particle shearing to looping has been investigated in the Al-Li alloy single crystals using optical microscopy, transmission electron microscopy and mechanical testing. The observation of slip-line morphology and of dislocation structures indicated the occurrence of a…