Materials Literature
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Abstract The theory of interdiffusion of a pair of components in multicomponent polymer mixtures is reviewed from a statistical point of view, and the foundation of the “fast” and “slow” mode theories, as well as the more recent “ANK” theory of interdiffusion is critically examined. The ANK theory reproduces the resul…
A novel InGaAs/InP micromachined thermoelectric sensor is presented. The key features of the reported sensors are the high thermal resistivity and high mobility of InGaAs lattice matched to InP, combined with a value of Seebeck coefficient that is acceptable for such applications. The anisotropic and selective surface…
Raman spectroscopy was applied to silicon carbide/carbon continuous fibre-reinforced ceramic matrix composites to study the microstructure and composition changes in the fibres in the matrices after the consolidation of the composite at high temperatures by hot pressing, and also the stress distributions in the compos…
Poly[4-(4‘,4‘,5‘,5‘-tetramethyl-3‘-oxido-1‘-oxylimidazolinium-2‘-yl)-1,2-phenylenevinylene] ( 1 ) and poly[4-[(3,5-di- tert -butyl-4-oxyphenyl)(3,5-di- tert -butyl-4-oxocyclohexa-2,5-diene-1-ylidene)methyl]-1,2-phenylenevinylene] ( 2 ) were synthesized via the polymerization of 2-bromo-4-[1‘,3‘-bis( tert -butyldimethy…
Crack-free and transparent PbTiO3 thin films with a perovskite structure were deposited on NaCl (100), Si(111), and fused quartz substrates by the sol-gel method. The crystal structure, morphology, domain structure, composition, and optical properties of the films were characterized by means of x-ray diffraction, tran…
Some results of work carried out on flame retarding of cotton and wool fabrics are reviewed.* Cotton fabrics are rendered flame retardant upon treatment with ammonium sulfamate (AS) with urea or a urea-based cross linking agent, as co-additive, in the pad-dry-cure finishing treatment, with curing at 180-200°C for one…
Two mechanisms of microbially influenced corrosion (MIC) are discussed and compared: corrosion modified by the presence of (1) sulfate-reducing bacteria (SRB) and (2) manganese-oxidizing bacteria (MOB). It is demonstrated that the nature of MIC in both cases depends on the nature of inorganic materials precipitated at…
Abstract Chlorination, bromination and iodination of bis(methylthio)tetrathiafulvalene (BMT-TTF) produced mainly the dihalogenated products (BMT-TTFX2) with small amounts of the monohalogenated derivatives (BMT-TTFX). The molecular structures of BMT-TTFBr2 and BMT-TTFBr2•I3 have been determined, and the conductivities…
The solid-state phase transformations and crystallography of equiatomic TaRu were examined by conventional and in-situ high-temperature transmission electron microscopy, with complementary experiments using X-ray diffraction and dilatometry. This alloy undergoes two displacive phase transformations on cooling from the…
Indium has replaced all of the Tl + ions in fully dehydrated fully Tl + -exchanged zeolite A by a solvent-free redox ion-exchange reaction with In metal at 623 K. The crystal structures of the zeolite before (Tl 12 Si 12 Al 12 O 48: a = 12.153(4) Å, R 1 = 0.054, and R 2 = 0.060) and after the reaction, followed by was…
The complete carbonylation mechanism for the model palladium(II) system, Pd(PH 3 )(CH 3 )(N-O) + CO → Pd(PH 3 )(COCH 3 )(N-O) (N-O = NHCHCOO - ), has been investigated employing nonlocal density functional theory (DFT) and second-order Møller−Plesset perturbation theory (MP2). Four possible mechanisms were identified,…
We used the electron-beam evaporation method in various oxygen partial pressure environments to deposit TiO(2) thin films on various glass substrates at 300 degrees C. We found the threshold oxygen partial pressures above which the film is transparent are different for films on various substrates. Below the threshold…
The effect of composition (phase), texture, microstructure and thickness on electrical properties of Pb(Zr 1- x Ti x )O 3 (PZT) films have been evaluated. Zr-rich PZT films with [111] texture have a higher remanent polarization and dielectric constant, but a lower coercive field as compared with PZT[100] films. Ti-ric…
The dissolution of calcite (CaCO 3 ) in the presence of aqueous solutions containing maleic acid ( cis -HOOC−CH CH−COOH) in the pH range 4.3−8.2 has been studied by means of atomic force microscopy utilizing a flow cell of known hydrodynamics and modelable convection/diffusion. The latter permits the interpretation of…
The development of the concept of chirality from the early work of Pasteur, van't Hoff and Le Bel to the work of Cahn, Ingold and Prelog is presented, and the constraints that chirality imposes on the symmetry of molecules - that chiral molecules may not possess an improper axis of rotation - is discussed. The relatio…
It is proposed that melt-extrusion of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) at varying processing temperatures and screw speeds causes changes in the atomic positioning of the oxygen atoms in the helix structure due to torsion of the main chain bonds. By wide angle X-ray scattering it was observed that an incre…
The local structures of amorphous Ge0.52Te0.48 and Pd0.01Ge0.17Sb0.26Te0.56 were examined by extended x-ray absorption fine structure. In amorphous GeTe film, only Ge atoms were observed in the nearest-neighbor of Te atoms. The average coordination number around Te atoms in amorphous GeTe is 1.5 which is close to twof…
Photoablation of polyimide (Dupont Kapton™) and poly(ethylene terephthalate) (PET) (Dupont Mylar™) were studied in vacuum using 248 nm, 16 ns excimer laser pulses. A sensitive electron beam ionizer/quadrupole mass spectrometer detector was used to measure mass, translational energy, and angular distributions of the ne…
Optically reflective composite polyimide films have been prepared by casting a dimethylacetamide solution of silver(I) acetate, hexafluoroacetylacetone, and the poly(amic acid) derived from 3,3‘,4,4‘-benzophenone tetracarboxylic acid dianhydride (BTDA) and 4,4‘-oxydianiline (4,4‘-ODA) onto an fully imidized parent BTD…
The following article is Part II of a three-part series on the use of polymer insulating materials in outdoor insulation applications. Despite three decades of service history, polymer insulation materials do not have the same level of standardization as porcelain. As with any technology that is not well standardized,…