STRUCTURE AND PHYSICAL-PROPERTIES OF NEW PHASE OXIDE LA2MOO5

The compound La2MoO5 has a cubic fluorite symmetry. There is strong interaction between the two molybdenum ions (IV). The cubic-La2MoO5 oxide contains separated Mo2O8 clusters and is a semiconductor. The electrical resistivity measurement shows a semiconductor-metal transition around 250 degrees C. Temperature dependence of magnetic susceptibility represents the Curie-Weiss law. The compound La2MoO5 exhibits a paramagnetic behaviour from 170-250 K.

SYNTHESIS OF A POLYETHYLENE-GRAFT-POLYSTYRENE COPOLYMER AND ITS COMPATIBILIZATION FOR LINEAR LOW-DENSITY POLYETHYLENE/POLY(PHENYLENE OXIDE) BLENDS

Based on unsteady diffusion kinetics, polyethylene(PE)-graft-polystyrene (PS) copolymers were designed and synthesized with a heterogeneous high yield titanium-based catalyst by copolymerization of ethylene with a PS-macromonomer using 1-hexene as a short chain agent to promote the incorporation of the PS-macromonomer. The presence of 1-hexene facilitated the diffusion of the PS-macromonomer, giving rise to the significantly increased incorporation of the PS-macromonomer. Compatibilization of blends of linear low density polyethylene (LLDPE)/poly(phenylene oxide) (PPO) with the PE-g-PS copolymer were investigated using scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA).

MISCIBILITY STUDIES OF POLY(ETHYLENE OXIDE)-POLY(VINYL ACETATE) BLENDS BY VISCOMETRY METHODS

The intrinsic viscosities of poly(ethylene oxide)-poly(vinyl acetate) blends (PEO-PVA) have been measured in chloroform as a function of molecular weights of blend components and compositions. The interaction parameters Delta b obtained from the modified Krigbaum and Wall theory and the differences between the intrinsic viscosities of polymer mixtures and the weight-average intrinsic viscosities of the two blend components were both used to characterize the extent of miscibility of the blend mixtures. (C) 1995 John Wiley and Sons, Inc.

ELECTROCATALYTIC PROPERTIES OF MIXED-VALENCE MOLYBDENUM OXIDE THIN-FILM MODIFIED MICROELECTRODES

A compact blue conducting mixed-valence Mo (VI,V) oxide film was grown on the surface of a carbon fibre (CF) microelectrode by cycling the potential between +0.20 and similar to 0.70 V SCE in freshly prepared Na2MoO4 solution in H2SO4 (pH 2). The thicknes

COMPATIBILIZATION OF POLYPROPYLENE POLY(ETHYLENE OXIDE) BLENDS AND CRYSTALLIZATION BEHAVIOR OF THE BLENDS

The compatibilization of incompatible polypropylene (PP)/poly(ethylene oxide) (PEO) blends was studied. The experimental results showed that the graft copolymer [(PP-MA)-g-PEO] of maleated PP (PP-MA) and mono-hydroxyl PEO (PEO-OH) was a good compatibilize

STRUCTURE AND CATALYTIC ACTIVITY FOR PROPYLENE OXIDATION OF BI-MO-NB COMPLEX OXIDE CATALYSTS

The structure and catalytic,activity for propylene oxidation of series oxides B2Mo3-3X-Nb2XO12-4X (X=0.00, 0.02, 0.05, 0.10, 0.15, 0.20, 0.25) have been studied by means of XRD, IR, Raman, SEM, ESR and so on. The results showed that in the range of X < 0.

STUDIES ON THE SULFONATION OF POLY(PHENYLENE OXIDE) (PPO) AND PERMEATION BEHAVIOR OF GASES AND WATER-VAPOR THROUGH SULFONATED PPO MEMBRANES .3. SORPTION BEHAVIOR OF WATER-VAPOR IN PPO AND SULFONATED PPO MEMBRANES

Water vapor absorption and desorption by poly (phenylene oxide) (PPO) and sulfonated PPO (SPPO) membranes were studied at a constant temperature of 30-degrees-C and over a broad range of water activity (0.05 less-than-or-equal-to a < 0.8) by the weighing

STUDIES ON THE SULFONATION OF POLY(PHENYLENE OXIDE) (PPO) AND PERMEATION BEHAVIOR OF CASES AND WATER-VAPOR THROUGH SULFONATED PPO MEMBRANES .1. SULFONATION OF PPO AND CHARACTERIZATION OF THE PRODUCTS

Poly(2,6-dimethylphenylene oxide) (PPO) was sulfonated to varying degrees using different sulfonating agents. Physical properties such as solubility, density, and thermal properties were studied for both PPO and sulfonated PPO (SPPO) with different degree

STUDIES ON THE SULFONATION OF POLY(PHENYLENE OXIDE) (PPO) AND PERMEATION BEHAVIOR OF CASES AND WATER-VAPOR THROUGH SULFONATED PPO MEMBRANES .2. PERMEATION BEHAVIOR OF CASES AND WATER-VAPOR THROUGH SULFONATED PPO MEMBRANES

The permeation behaviors of water vapor and gases were studied for both PPO and SPPO of different sulfonation degree. It was found that the permeability of water vapor increased, and those of oxygen and nitrogen decreased; thus the selectivity for water v

Role of Lithium in Multicomponent Oxide Catalysts for Oxidative Coupling of Methane

The effect of Li content in a series of multicomponent oxides LixLa0.5Ti0.5 For methane oxidative coupling has been studied. The catalytic activities of LiLa0.5Ti0.5 catalyst before and after washing with boiling water have been compared. The surface and

ENHANCED AMPEROMETRIC DETECTOR FOR LOCAL-ANESTHETICS IN LIQUID-CHROMATOGRAPHY WITH METAL-OXIDE DISPERSED GLASSY-CARBON ELECTRODES

Chemically modified electrodes (CMEs) prepared by the dispersion of metal oxide particles on a glassy carbon (GC) substrate greatly enhance the voltammetric response and amperometric detection of local anesthetics following liquid chromatography (LC). The enhancement is more pronounced with the GC electrodes dispersed by the metal oxides of higher oxidation states (+3, +4) and for the species exhibiting relatively slow electrode kinetics under given conditions. With an applied potential of 1.2 V (vs. SCE), LC amperometric detection of the analytes at the alpha-alumina modified GC surface gives detection limits 2-5 times lower than those obtained at the bare electrode. The metal oxide-dispersed electrodes display significant improvement in sensitivity, and selectivity and indicate excellent preparation reproducibility and performance stability.

IMPEDANCE STUDY OF THE INTERFACES BETWEEN LITHIUM, POLYANILINE, LITHIUM-DOPED MNO2 AND MODIFIED POLY(ETHYLENE OXIDE) ELECTROLYTE

Impedance study was carried out for the interfaces between lithium, polyaniline (PAn), lithium-doped MnO2 and modified poly(ethylene oxide) (PEO) electrolyte under various' conditions. The interfacial charge-transfer resistances R(ct) on PEO/PAn, R(ct) on PEO/LiMn2O4 increase with depth-of-discharge and decrease after the charge of the cell containing modified PEO as electrolyte. The charge-transfer resistance R(ct) on PEO/PAn is higher than R(ct) on PEO/LiMn2O4 under the same condition, since inserted species and mechanism are different for both cases. In the case of PAn, an additional charge-transfer resistance might be related to the electronic conductivity change in discharge/charge potential range, as it was evident from a voltammetry curve. With increasing cycle numbers, the charge-transfer resistance increases gradually. The impedance results also have shown that at low frequency the diffusion control is dominant in the process of the charge and discharge of Li/PEO/PAn or Li/PEO/LiMn2O4 cell. The diffusion coefficients have been calculated from impedance data.

ELECTROCATALYSIS AND DETERMINATION OF HYDRAZINE COMPOUNDS IN LIQUID-CHROMATOGRAPHY AT A MIXED-VALENT COBALT OXIDE CYANOCOBALTATE FILM ELECTRODE

A glassy carbon electrode coated with an electrodeposited film of mixed-valent cobalt oxide/cyanocobaltate (Co-O/CN-Co) enabled hydrazine compounds to be catalytically oxidized at the greatly reduced overpotential and in a wide operational pH range (pH 2.0-7.0). Electrocatalytic activity at the Co-O/CN-Co modified electrode was evaluated with respect to solution pH, film thickness, supporting electrolyte ions, potential scan rate, operating potential, concentration dependence and other variables. The Co-O/CN-Co film electrode was completely compatible with a conventional reversed-phase liquid chromatographic (RP-LC) system. Practical RP-LC amperometric detection (RP-LCEC) of hydrazines was performed. A dynamic linear response range over three orders of magnitude and a detection limit at the pmol level were readily obtained. The Co-O/CN-CO film electrode exhibited excellent electrocatalytic stability in the flowing streams.

SYNTHESIS AND MOLECULAR-STRUCTURE OF NBU2[(MEO)3C6H2C(O)N2CHC6H4O]SN FORMED IN THE REACTION OF DI-N-BUTYLTIN(IV) OXIDE WITH 3,4,5-TRIMETHOXY-BENZOYL SALICYLAHYDRAZONE

The title complex was synthesized and characterized by H-1, C-13, Sn-119 NMR and IR spectra. A single crystal X-ray diffraction study confirmed its molecular structure and revealed that 3,4,5-trimethoxy-benzoyl salicylahydrazone was a tridentate and approximately planar ligand. The complex crystallizes in the triclinic space group P1BAR with a = 9.208(3), b = 12.536(2), c = 12.187(4) angstrom, alpha = 113.12(2), beta = 90.58(2), gamma = 81.42(2), V = 1277.5(6) angstrom, Z = 2. The structure was refined to R = 0.033 and R(w) = 0.041 for 3944 observed independent reflections. The tin atom has a distorted trigonal bipyramidal coordination. The Sn-C bond lengths are 2.129(5) and 2.113(5) angstrom (av. 2.121(5) angstrom), the C-Sn-C angle is 123.3(2); the bond length between the tin atom and the chelating nitrogen is 2.173(3) angstrom. Two chain carbon atoms and the chelating nitrogen atom occupy the basal plane. The skeleton of two erect oxygen atoms and the tin atom is bent (O-Sn-O angle = 153.5(1)). In the complex, the ligand exists in the enol-form.

THERMODYNAMICS OF POLY(ETHYLENE OXIDE)-POLY(VINYL ACETATE) BLENDS

Heat-of-mixing data, obtained on blends of poly(ethylene oxide) (PEO) with whole and fractionated poly(vinyl acetate) (PVAc), were used to feed Patterson's theory of polymer-polymer miscibility. Negative values of mixing enthalpy, contact-energy term, interaction'' parameter and excess volume were obtained only for blends with the lowest molecular weight PVAc fraction. These results show that miscibility of PVAc with PEO strongly depends on its molecular weight. The calculated unfavourable excess volume term of the Patterson equation is small in comparison with the absolute value of the interaction term. Therefore, miscibility of PEO and low-molecular-weight PVAc is dictated by the weak specific interactions between different repeat units and by the entropic gain in the mixing process.