Study on the Adsorption and Activation of NO and CO over Mixed Oxide Catalysts Containing Cu by Means of TPSR

Adsorption and activation of small molecules NO, CO and CO+ NO on LaSrCuO4, La2CuO4 and La1.7Th0.3CuO4 which are typical samples in the sence of nonstoichiometric oxygen(lambda) anrong the series of La2-x(SrTh)(x)CuO4 +/-lambda mixed oxide catalysts were studied by means of MS- TPD (TPSR ), XRD, chemical analysis and so on. It was shown that the adsorption amount of NO can be correlated with the content of oxygen vacancy while the types and strength of adsorption of NO could be related to the oxidation state of the metallic ion. It was also found that CO molecule was first converted into CO32- and then desorbed in the form of CO2 at high temperature during the adsorption and desorption of CO on the mixed oxide with oxygen vacancy. The fact that the profiles of TPD(TPSR) of NO in co-adsorption of NO+CO and in single NO adsorption are similar shows that the adsorption of NO molecule not only has some priority to that of CO but also is stronger than that of CO. It seems that the adsorption of NO plays a dominate role in the activation and decomposition of NO.

The synthesis and thermotropic liquid crystalline behavior of the novel poly(aryl ether ketone)s containing chloro-side group

The novel poly(aryl ether ketone)s containing chloro-side group were synthesized by nucleophilic substitution reactions of 4,4'-biphenol and chlorohydroquinone with either 4,4'-difluorobenzophenone(BP/CH/DF) or 1,4-bis(p-fluorobenzoyl)benzene (BP/CH/BF) and their thermotropic liquid crystalline properties were characterized by a variety of experimental techniques. The thermotropic liquid crystalline behavior was observed in the copolymers containing 50 and 70% biphenol. Melting transition (Tm) and isotropization transition (Ti) both appeared in the DSC thermograms. A banded texture was formed after shearing the sample in the liquid crystalline state. The novel poly(aryl ether ketone)s had relatively higher glass transition temperature (Tg) in the range of 168 similar to 200 degrees C and lower melting temperature (Tm) in the range of 290 similar to 340 degrees C. The thermal stability (Td) was in the range of 430 similar to 490 degrees C.

Study of the blends containing core-shell latex polymer

Polycarbonate (PC) and a core-shell latex polymer composed of poly(butyl acrylate) and poly(methyl methacrylate) (PBA-cs-PMMA) as core and shell, respectively, were mixed using a Brabender-like apparatus under different conditions. The mechanical properties, the morphology and the processability of the blends were investigated. Because of the good compatibility of PC and PMMA, even dispersion of PBA-cs-PMMA in PC matrix and good adhesion between the components have been achieved. PBA-cs-PMMA is thus a very good impact modifier for PC. The toughening mechanism is both cavitation and shear yielding, as indicated by SEM observation. (C) 1997 Elsevier Science Ltd.

Enzymatic degradation of poly(epsilon-caprolactone) film in phosphate buffer solution containing lipases

The enzymatic degradation of poly(epsilon-caprolactone) (PCL) films in phosphate buffer solution containing lipases has been studied by DSC, WAXD and SEM. Three lipases, pseudomonas lipase (PS), porcine pancreatic lipase (PP), and candida cylindracea lipase (AY), were used. The results showed that the degradation of PCL films in phosphate buffer solution containing PP or AY was very slow: no weight loss could be found within 1 week. However, PCL film could degrade rapidly and completely within 4 days in phosphate buffer solution containing PS lipase. (C) 1997 Elsevier Science Limited.

Novel poly(aryl ether ketone)s containing various pendant groups .2. Gas-transport properties

The gas transport of hydrogen, oxygen, nitrogen, carbon dioxide, and methane gases in a series of poly(aryl ether ketone)s was examined. These polymer membranes have a wide range of permeability coefficients and permselectivity coefficients, showing excellent gas-transport properties. The enhanced interchain interaction in the polymers due to intermolecular hydrogen bonds and ionic bonds results in a considerable increase in permselectivity but a decrease in permeability. On the contrary, the polymers with bulky arkyl substituents show significantly increased permeability. The causes of this trend are interpreted in terms of the free volume, interchain distance, and glass transition temperature together with the respective contribution of gas solubility and diffusivity to the overall permeability. Of interest is the observation that the ionomer IMPEK-K+, which simultaneously contains bulky isopropyl substituents and pendant carboxylate groups, exhibits over twice higher CO2 permeability and 15% higher CO2/CH4 permselectivity than those of bisphenol-A p'olysulfone (PSF). The possibility of using the new synthesized poly(aryl ether ketone)s in gas separation membrane application is also discussed. (C) 1997 John Wiley & Sons, Inc.

Mass spectral study of extractable La- and Lu-containing fullerenes

Mass spectra of LaxC2n (x = 1,2), well known endohedral metallofullerenes, and Lu2C2n (2n = 76-112), new members of extractable metallofullerenes, were studied. Positive-ion laser desorption/ionization (LDI) and electron impact (EI) mass spectra indicated that lutetium is a special lanthanide that prefers to form dilutetium fullerenes by the are-burning method. However, the signals for Lu2C2n become very weak in negative-ion LDI-MS, this is different from La-2@C-80, which has close relative abundances in positive- and negative-ion MS. The distinction between Lu2C2n and La-2@C-80 in the negative-ion LDI mass spectra may be due to the different structures of La- and Lu-containing fullerenes. (C) 1997 by John Wiley & Sons, Ltd.

Crystallization process and morphology structure of poly(aryl ether ether ketone ketone) containing meta-phenyl links

The crystallization process and morphology of poly(aryl ether ether ketone ketone) containing meta-phenyl links (PEEKmK) have been investigated by transmission electron microscopy and electron diffraction. The results indicate that the thin films of PEEKmK isothermally crystallized from both the glassy state and the melt at the temperature range of 180 similar to 250 degrees C consist of two kinds of morphological forms, i. e. large (order of mu m), flat-on single crystals and narrow, lath-like, edge-on lamellae, The latter consists of the spherulites. Meanwhile, the growing process of the two kinds of morphological forms has been discussed.

Radiation-induced crystallization of polyamide-1010 containing heterogeneous nuclei

Radiation-induced crystallization of polyamide-1010 (PA1010) or nylon-1010 containing heterogeneous nuclei (neodymium oxide, Nd2O3) is discussed in this paper by Wide Angle X-ray Diffraction (WAXD) and Differential Scanning Calorimetry (DSC). The results show that at low dosage the crystallinities of the irradiated specimens increase, while crystallite size (L(hkl)) decreases, indicating that some new crystallites are produced in the course of irradiation. The new centers were brought about in the fold surface of the lamellae. Copyright (C) 1997 Elsevier Science Ltd

Novel polyaryletherketones containing various pendant groups .1. Synthesis and characterization

Novel high glass transition temperature polyaryletherketones, containing pendant amido, alkyl, and carboxyl groups with reduced viscosity above 0.54 dL/g, were synthesized via solution nucleophilic polycondensation reaction of phenolphthalin, 2',2 ''-diisopropyl-5',5 ''-dimethylphenolphthalin, and 3,3'-bis(4-hydroxyphenyl)isobenzopyrrolidone with bis(4-nitrophenyl)ketone in the presence of potassium carbonate. By ion exchange with Na+ and K+, four ionomers were also prepared. A new monomer simultaneously containing carboxyl and algyl substituents was synthesized by reduction reaction of 2',2 ''-diisopropyl-5',5 ''-dimethyl-phenolphthalein. The resulting polymers were soluble in a few polar aprotic solvents; transparent, colorless, and tough films could easily be cast from DMF or DMSO solution. The mechanical properties of the films were excellent; and their tensile strength, elongation at break, and tensile moduli were in the range of 67.1-97.1 MPa, 7.8-165%, and 1.47-2.27 GPa, respectively. The prepared polymers showed fairly good thermal stability and resonably high glass transition temperatures above 210 degrees C. (C) 1997 John Wiley & Sons, Inc.

gamma-Radiation damage to nylon 1010 containing neodymium oxide

A comparison of radiation damage to nylon 1010 (denoted nylon-a) and nylon 1010 containing neodymium oxide (Nd2O3) (denoted nylon-b) was made by DSC, WAXD, ESR and the determination of gel fractions. The results show that radiation damage to nylon-b is delayed, and radiation damage to nylon-a is more severe than that to nylon-b, due to the protection of the fold surface of the lamellae. Furthermore, the fact that the damage begins with the fold surface of the lamellae is confirmed. (C) 1996 Elsevier Science Limited

A new solid-state electrolyte: Rubbery 'polymer-in-salt' containing LiN(CF3SO2)(2)

A new class of rubbery 'polymer-in-salt' electrolytes for application in solid-state lithium batteries has been explored by differential scanning calorimetry and a.c. impedance analysis. Simple phase diagrams of LiN(CF3SO2)(2)+LiClO4 and LiC(CF3SO2)(3)+LiN(CF3SO2)(2) have been drawn, which are very important to determine polymer-in-salt electrolyte materials. The conductivities obtained by a.c. impedance measurement are smaller for the electrolyte that contains acetate LiOAc salt than for the electrolyte without this salt.

Synthesis and properties of poly(aryl ether ether ketone ketone) containing meta-phenyl links

A Series of poly(aryl ether ether ketone ketone) containing meta-phenyl link were synthesized, the general properties were studied by DSC, stretch, impact, etc.. The results indicated that with the raising of meta linkage monomer fractions, the glass transition point decreased, the melting temperature decreased at first, and then disappeared, but for all-meta-linked polymer, T-m appeared once more. And this kind of polymer had good stretch and impact resistance performance.

Gas permeation properties of cardo polyaryletherketones containing different alkyl substituents

The gas permeation properties of a series of cardo polyaryletherketone materials are reported, In this series, the hydrogen atoms of benzene rings on the backbone are systematically replaced with different alkyl substituents. The effects of temperature and structure variation on gas permeability and selectivity are discussed in detail. The experimental results revealed that the polyetherketone obtained by the introduction of dimethyl and diisopropyl substituents to phenolphthalein unit is 3 similar to 6 times more permeable than the unmodified one for the gases studied.

Investigation of irradiated PA1010 containing heterogeneous nuclei

This paper deals with radiation effects on PA1010 containing heterogeneous nuclei (Nd2O3). With the help of DSC, WAXD and ESR techniques, the change in the crystallinity and the perfection of the crystal of irradiated PA1010 containing heterogeneous nuclei were studied. Copyright (C) 1996 Elsevier Science Ltd.

Synthesis and properties of poly(aryl ether ketone)s containing meta-phenyl links

A series of poly(aryl ether ketone)s containing meta-phenyl links are synthesized, DSC and wide-angle X-ray scattering, etc, are used to study the general properties of the polymers, With the increasing of meta linkage monomer percentage, the melting temperature decreases sharply at first, then rises steadily, the glass transition point. keeps a stable value, and crystallin;ty and crystallizing rate are reduced, A part of amorphous film of the polymer is annealed at different temperatures, DSC scan shows that besides T-m, a new melting peak (T-m') at low temperature appears, And with heat treating temperature rising, T-m' shifts to high temperature, and T-m keeps a stable value.