Materials Literature
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A negative working photosensitive polyimide based on poly(hydroxyimide) (PHI), 2,6-bis(hydroxymethyl)-4-methylphenol (BHMP) as cross-linker, and photoacid generator diphenyliodonium 9,10-dimethoxyanthracene-2-sulfonate (DIAS) has been developed. The PHI was prepared by the ring-opening polyaddition of 4,4‘-hexafluoroi…
The crystal structure of the stable crystalline form of syndiotactic polypropylene (s-PP) may be taken, only as a first approximation, as body-centered orthorhombic and described in the space group Ibca (in which the chains maintain their full, ideal 2 1 22 symmetry). Indeed, the splitting of the resonance of the meth…
Pyrroles fused with aromatic rings (isoindole derivatives) have been readily prepared by the reaction of aromatic nitro compounds with ethyl isocyanoacetate in the presence of DBU. The ease of this reaction depends on the aromaticity of the starting nitro aromatics. Polycyclic aromatic nitro compounds such as 1-nitroa…
Blends composed of poly(vinylphenol) (PVPh) and bacterial (tactic) poly(hydroxybutyrate) (PHB) and synthetic (atactic) poly(hydroxybutyrate) (PHBa) have been investigated by FTIR. From quantitative analyses of hydrogen bonded PHB carbonyl groups as a function of temperature and composition, the interassociation consta…
Low-temperature (400−800 °C) stabilization of tetragonal zirconia, prepared by a hydroxide gel route and low-temperature annealing, has been achieved by partial substitution of Zr 4+ with Bi 3+ . XRD and Raman spectroscopy have been used for characterization of the doped zirconia powders as well as for identification…
The surface forces apparatus technique was used to measure the normal forces, thin film viscosity, and lateral (frictional) forces between two surfaces interacting across 4‘- n -octyl-4-cyanobiphenyl (8CB), to determine the effects of confinement (film thickness) and shear (sliding velocity) on the ordering of the sme…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSingle-Crystal X-ray Structure of the Cation Radical of 3',4'-Dibutyl-2,5''-diphenyl-2,2':5',2''-terthiophene: Definitive Evidence for π-Stacked Oxidized OligothiophenesDavid D. Graf, John P. Campbell, Larry L. Miller, and Kent R. MannView Author Information Department…
The deformed structure of cold rolled IF steels consists of a large number of α fibre and γ fibre oriented grains and a small number of (110)<110> oriented grains, each with a distinctive grain shape, subgrain structure, hardness and etching appearance. Early nucleation occurs mainly in γ fibre grains and (110)<110> g…
Layered double hydroxides containing silicate anions have been prepared using either a coprecipitation method or an anionic exchange reaction. The polymerization of the intercalated anions under moderate thermal treatment has been studied by PXRD, FTIR, and solid-state NMR. Grafting processes and layer condensation ha…
Deterioration of stator winding insulation continues to be one of the predominant causes of large motor and generator failures. Over the past several years, practical methods have been developed for measuring the partial discharge activity in the high voltage insulation of stator windings, since partial discharges are…
The super-H-shaped block copolymers belong to a new class of polymeric materials, the miktoarm stars (mikto from the Greek word μικτο ς meaning mixed), which includes star-shaped polymers in which from one or more junction points radiate different arms. Schematically, the super-H structure can be described as two thre…
1 H nuclear magnetic resonance (NMR) relaxation studies of the temperature-induced micellization of a poly(ethylene oxide)−poly(propylene oxide)−poly(ethylene oxide), PEO−PPO−PEO, block copolymer in aqueous solution were performed in the range 280−345 K. 1 H NMR spectra of the block copolymer were well resolved, thus…
Nonlinear optical (NLO) copolyimides exhibiting high glass transition temperatures ( T g ) and high thermal stabilities were synthesized to achieve long-term stability of optical nonlinearity at elevated temperatures. The relationship between the chromophore loading level and the physical properties of the copolymers…
Abstract A new polysaccharide‐based polycarboxylate, carboxymethyl inulin (CMI), was synthesized recently. The influence of small amounts (0.1–200 ppm) of this material on the crystallization of calcium carbonate, an important scale‐forming salt, is studied. The effects of CMI are compared to those of a commercial inh…
Reversible photorelease of Li + and Ca 2+ cations from complexes with a crowned derivative of the merocyanine dye DCM (4-(dicyanomethylene)-2-methyl-6-( p -(dimethylamino)styryl)-4 H -pyran) in acetonitrile is investigated by steady-state and time-resolved spectroscopy. The results obtained by fluorescence spectroscop…
Catalytic epoxidation of monoterpenes with aqueous hydrogen peroxide catalyzed by peroxotungstophosphate (PCWP) under biphase conditions using chloroform as the solvent was examined. A variety of terpenes was oxidized to the corresponding monoepoxides or diepoxides in good yields under mild conditions. For example, li…
In this article we briefly review the literature for the evaporated metals gold, silver, copper, palladium, chromium, and potassium on polyimide surfaces and compare these previous results to newer experiments using Fourier transform infrared reflection absorption spectroscopy (FT-IRAS) and near edge X-ray absorption…
We use scaling arguments and self-consistent field calculations to determine the behavior of AB diblock copolymers that are grafted to a planar surface at relatively low densities. The surrounding solution is assumed to be a theta or marginally good solvent for the A block and a poor solvent for the B block. When the…
In various activated sludge systems, sludge grows under transient (unbalanced) conditions and storage of internal polymers becomes important. Differences in storage capacity under transients are often used to explain kinetic control of bulking, but storage is neither studied in detail nor usually included in modelling…
Edible films were prepared using a combination of rice protein concentrate and the polysaccharide pullulan. The protein-pullulan mixture with up to 50% protein concentrate could be cast on a glass plate into films with tensile strength of about 18 MPa and water vapor permeability of 40 g x mil/m 2 x day x mmHg. Film s…