Degradation of poly[bis(ethylamino)phosphazene] in aqueous solution

Three polymers of poly[bis(ethylamino)phosphazene] (PBEAP) containing different amounts of the residual P–Cl moieties, which had been hydrolyzed into P OH in the following sample purification processes, were prepared by substitution of the chlorines on poly(dichlorophosphazene) with ethylamine. Only the polymer which had the highest side-chain content of ethylamino groups (ca. 93°_o) had a film-forming ability and a crystalline nature. The hydrolytic degradation of PBEAP in acidic solutions was investigated using the solution viscosity data obtained as a function of standing time. Acetic acid, 0.5 and 1N, pure acetic acid, and 2.2.2-trifluoroethanol were used as solvents. The degradation was composed of random breaking processes along the polymer chain, especially at the-N=P(OH)₂-and-N=P(OH)(NHC₂H₅)-units, and an unzippering-like breaking process which was started at the chain ends produced by the former random breaking. The random breaking caused an abrupt decrease in viscosity at the beginning of the degradation, and on the contrary, the unzippering-like breaking appeared as a gradual decrease in viscosity at the later stages of degradation. The total rate of degradation depended on the concentration of the ethylamino groups.     

Fabrication of Transparent Yttria Ceramics by the Low-Temperature Synthesis of Yttrium Hydroxide

Thin flakes of yttrium hydroxide agglomerated in a manner resembling houses of cards with aging at 10°C. The agglomerate then dissociated into fine yttria particles with calcination at >800°C. The particle size of the calcined powder increased appreciably as the calcination temperature increased. The shrinkage curve indicated similar densification behavior among undoped yttria powders calcined at 800°–1000°C, despite considerable particle growth as the calcination temperature increased. Increasing the calcination temperature to >1000°C shifted the shrinkage curve appreciably to the high-temperature region. Sulfate-ion-doped yttria particles had round edges, irrespective of calcination temperature, in contrast to the sharp edges of the undoped yttria particles. A calcination temperature of <1000°C resulted in skeleton yttria particles, which exhibited poor sinterability. At a calcination temperature >1000°C, the skeleton particles dissociated into monodispersed particles that densified easily. When the calcination temperature was >1000°C and the average particle sizes were similar, the undoped and sulfate-ion-doped yttria showed similar densification rates. The transparency of the sintered yttria ceramics was dependent on both the calcination temperature and sulfate-ion doping: that is, sulfate-ion doping and calcining at 1100°C were both necessary conditions for the fabrication of a transparent body.     

Influence of Oxygen Ion Conduction on Nitric Oxide Decomposition

Ba₂In₂O₅, Ba₂Y₄O₉, and BaLa₂O₄ having brownmillerite-related structures were synthesized. Ionic conductivity and catalytic activity following the reduction of NO to N₂ were also investigated, both of which increased at the order-disorder transition temperature for oxygen vacancies of these compounds. It was made clear that the catalytic activity of NO decomposition reaction increased with a decrease in the order–disorder transition temperature. Moreover, it was found that ionic conductivity contributed to the catalytic activity of NO reduction to N₂.     

Internal stress of epoxy resin modified with acrylic core-shell particles prepared by seeded emulsion polymerization

In order to reduce the internal stress in a cured epoxy resin, the submicron polymer particles were dispersed therein prior to curing. For this purpose, four kinds of poly(butyl acrylate), poly(methyl methacrylate) core-shell particles were prepared by seeded emulsion polymerization for methyl methacrylate with poly(butyl acrylate) seed particles having different particle diameter, and subsequently were powdered by drying at room temperature. It was observed by SEM that poly(butyl acrylate) particles as core were dispersed in the cured epoxy matrix. Poly(methyl methacrylate) as shell seems to dissolve in the matrix. The internal stress of cured epoxy resin decreased with the modification of the particles and the tendency was enhanced with a decreasing in the particle diameter.     

Test results of a catalytically assisted combustor for a gas turbine

A catalytically assisted ceramic combustor for a gas turbine was designed and tested to achieve low NO_x emissions. This combustor is composed of a burner and a ceramic liner. The burner consists of an annular preburner, six catalytic combustor segments and six premixing nozzles, which are arranged in parallel and alternately. In this combustor system, catalytic combustion temperature is controlled under 1000 °C, premixed gas is injected from the premixing nozzles to the catalytic combustion gas and lean premixed combustion over 1300 °C is carried out in the ceramic liner. This system was designed to avoid catalyst deactivation at high temperature and thermal shock fracture of the ceramic honeycomb monolith of the catalyst. A 1 MW class combustor was tested using LNG fuel. Firstly, NO_x emissions from the preburner were investigated under various pressure conditions. Secondly, two sets of honeycomb cell density catalysts and one set of thermally pretreated catalysts ware applied to the combustor, and combustion tests were carried out under various pressure conditions. As a result, it was found that the main source of NO_x was the preburner, and total NO_x emissions from the combustor were approximately 4 ppm (at 16% O₂) at an adiabatic combustion temperature of 1350 °C and combustor inlet pressure of 1.33 MPa.     

Nanohybrid polymer prepared by successive polymerization of methacrylate monomer containing silver nanoparticles in situ prepared under microwave irradiation

The well-dispersed silver nanoparticles were prepared in reactive methacrylate monomers under microwave irradiation without polymerization. In contrast to conventional heating, the synthesis of Ag nanoparticles proceeded uniformly throughout the reaction vessel only under microwave irradiation, reaching the completion of the reaction simultaneously in the whole reaction solution. Successive polymerization of the monomer containing the resulting nanoparticles has successfully produced a monohybrid of the silver nanoparticles dispersed in polymer matrix.     

Fixation and conversion of CO2 using ionic liquids

Ionic liquids (ILs), a kind of novel green media composed entirely of cations and anions, have recently attracted considerable attention due to their unique properties such as non-volatility, tunable polarity, high stability and so on. In this work, the latest progress on the fixation and conversion of carbon dioxide (CO₂) using ILs as absorbents, catalysts or promoters has been summarized. The absorption performance of conventional ILs and task-specific ILs was systematically investigated, the conversion of CO₂ with epoxides, propargyl alcohols and amines using ILs was critically evaluated, and the significant advantages in the fixation and conversion of CO₂ using the ILs were demonstrated compared to the conventional absorbents and the catalytic systems without ILs. This research progress may finally lead to building of an in situ fixation–conversion process of CO₂ with ILs. If so, we are near an epoch of the fixation and utilization of CO₂, although there is obviously a long way to go for us to achieve such a goal.     

Synthesis of (4S, 10R, 11S)-4-Methyl Juvenile Hormone I by Using Chiral Building Blocks of Biochemical Origin

The title compound 1 was synthesized starting from (2S, 3S)-2-ethyl-3-hydroxy-2-methylcyclohexanone ( B ) and (R)-3-methyl-5-pentanolide ( 3 ). The key step for the preparation of B was the reduction of the corresponding diketone with a yeast, Pichia terricola KI0117, and that for the preparation of 3 was pig liver esterase (PLE)-catalyzed hydrolysis of C to give D.     

Gels of syndiotacticity-rich poly(vinyl alcohol)–water/dimethyl sulfoxide or – water/ethylene glycol solutions

Gels of syndiotacticity-rich poly(vinyl alcohol) (s-PVA) in mixed solvents of water/dimethyl sulfoxide (DMSO) or water/ethylene glycol (EG) were made by chilling at the temperatures of 0–70°C from those solutions with the polymer concentrations below 10g/dL. The melting points of the gels were measured warming the gel from the gelling temperature (T_gel) at a constant heating rate. The apparent enthalpy of fusion of a junction of gel, ΔH was estimated from the relation between the apparent melting temperature and the polymer concentration. The s-PVA gels made from the mixtures of the water/lower contents of DMSO or EG had a minimum at lower T_gel and a maximum ΔH at a higher T_gel. On the other hand, the s-PVA gels made from the mixtures of the water/higher contents of them had nearly a maximum ΔH at a higher T_gel. From those results, it was considered that the former gels received a high thermal history while the latter gels received only slight thermal history.