Materials Literature
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Toughening of polypropylene was carried out by adding two types of ethylene-propylene rubber (EPR) having different ethylene content, and three commercial types of EPR containing high density polyethylene (PE). The concentration of EPR was varied from 0–30%. Globular morphology of the dispersed phase was observed at a…
New fluorinated thermoplastic elastomers (FTE) with perfluoropolyether (PFPE) blocks have been synthesized by reacting a fluorinated macrodiol with aromatic diisocyanates in the presence of a solvent, followed by subsequent chain extension with low molecular weight aliphatic or aromatic diols. Tensile properties measu…
An interfacial model was proposed for the ternary thermoplastics (matrix)/elastomer/rigidparticle filler composite with high strength, high toughness, and high modulus. A dispersed phase of rigid particle as a core and elastomer as a shell that has a good interfacial adhesion with the matrix is the key point of the mo…
ADVERTISEMENT RETURN TO ISSUEPREVArticleMetalloporphyrins as Initiators for Living and Immortal PolymerizationsTakuzo AidaTakuzo AidaDepartment of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, JapanMore by Takuzo Aida and Shohei Inoue*Shohei InoueDep…
Three complexes of the general form [SbCl 3 ] 4 ·[Ph−Ph] ([Ph−Ph] = bibenzyl, trans -stilbene, or diphenylacetylene) have been isolated in high yield as crystalline solids. The characteristics of the new materials significantly differ from those of the precursors, and their solid state structures have been determined…
A general kinetic model to describe the interaction of two dissimilar olefins with cobalt(II) tetrakis(anisyl)porphyrin complexes in the presence of organic radicals has been developed. The kinetic scheme presumes the formation of organometallic products both by radical addition to Co(II) and by reaction of hydridocob…
We present a theoretical approach to study the dielectric properties of porous ceramics and composite materials and explain the experimentally observed notable influence of the coupling between the components of a saturated porous ceramic on the final behavior of the sample. This model is based on the assumption of a…
The results of susceptibility and neutron inelastic scattering measurements on the pyrochlore compound are presented. The crystal-field ground state of the ion has zero spontaneous magnetization, and a virtually dispersionless crystal-field excitation is observed. It is concluded that the crystal-field interaction dom…
The effect of crystallization temperature on the electrical properties of sol-gel derived Pb(Zr,Ti,Nb)O3 or PNZT capacitors with La0.5Sr0.5CoO3 (LSCO) electrodes has been investigated. It is demonstrated that LSCO//PNZT(4/30/70)//LSCO capacitors can be fabricated at temperatures as low as 550 °C without significant de…
The configurational properties of a heteropolymer with prescribed sequences of known concentrations of dipolar segments are investigated. The theoretical analysis of a model chain capable of aggregation into domains shows that entropic frustrations lead to localized structures. In these structures, polymer size is det…
To investigate the observed huge variations in magnetoresistance between different samples of manganite perovskites we have performed the first high-pressure measurement of magnetoresistance in single crystal ${\mathrm{Nd}}_{0.5}{\mathrm{Sr}}_{0.36}{\mathrm{Pb}}_{0.14}{\mathrm{MnO}}_{3\ensuremath{-}\ensuremath{\delta}…
Helical strands from P2 and P10 units (see structure below), recently predicted by ab initio calculations to be thermodynamically stable, and shortly thereafter discovered as a structural element in (CuI)3P12, might be the major component of amorphous red phosphorus. Radial distribution functions calculated on the bas…
Epoxidations of olefins and oxidations of alcohols can be carried out in the presence of peroxides at relatively low temperatures with Cu2+ histidine complexes that have been immobilized in zeolite cavities (structure from molecular modeling shown on the right). Combined diffuse reflectance and ESR spectroscopic studi…
The dragline silk spun by spiders exhibits unusual tensile strength and the energy required to break it can be higher than that of Kevlar. In his Perspective, Tirrell comments on a research report in the same issue by Simmons et al . ( p. 84 ) that elucidates some of the structural properties that give spider silk its…
The redox behavior is markedly different for the second generation dendrimer 1 (depicted on the right) from that of the first generation dendrimer without the densely packed dendritic structure. The unusually positive FeIII/FeII redox potential of 1 in water (+0.19 V vs. SCE) is attributable to the strong shielding of…
At least four types of silanol groups are present in MCM-41, a novel silicate with uniform mesopores, according to IR spectroscopy. Isolated silanol groups (type 1 in the picture on the right) and those involved in hydrogen bonds were distinguished by partial silylation with chlorotrimethylsilane (CTMS) and chlorotrip…
A complete and accurate set of experimental crystallographic phases to a resolution of 1.8 angstroms was obtained for a 230-residue dimeric fragment of rat mannose-binding protein A with the use of multiwavelength anomalous dispersion (MAD) phasing. An accurate image of the crystal structure could thus be obtained wit…
The first report of the formal potentials of a series of solid metal hexacyanometalates (M + ) n M′[M″ (CN) 6 ] is given (M + = Li + , K + , Na + , Rb + , Cs + ; M′ = Ag, Al, Cd, Co, Cr, Cu, Fe, Ga, In, Mn, Ni, Pb; M″ = Cr, Fe, Mn). A linear correlation exists between the ionic potential Φ = z /r eff of the nitrogen‐b…
The computation of the electron-electron Coulomb interaction is one of the limiting factors in ab initio electronic structure calculations. The computational requirements for calculating the Coulomb term with commonly used analytic integration techniques between Gaussian functions prohibit electronic structure calcula…
Molecular-based ferrimagnetic thin films with high critical temperatures ( T c ) composed of mixed-valence chromium cyanides were synthesized by means of a simple electrochemical route. The highest T c was 270 K, obtained for Cr 2.12 (CN) 6 . The T c values were easily controlled by changing the preparation conditions…