Thermo‐Physical and Impact Properties of Epoxy Containing Epoxidized Linseed Oil, 2

Summary: Biobased neat epoxy materials containing epoxidized linseed oil (ELO) were processed with an amine curing agent. A defined amount of diglycidyl ether of bisphenol F (DGEBF) was replaced by ELO. The thermophysical properties of the amine‐cured biobased neat epoxy were measured by dynamic mechanical analysis (DMA). The Izod impact strength increased with an increase in the amount of ELO added. The change in the Izod impact strength was correlated with the thermophysical properties measured by DMA.

Relation between the Izod impact strength and loss factor for amine‐ and anhydride‐cured ELO‐containing epoxy resins.     

Thermally initiated cationic polymerization and properties of epoxy siloxane

Difunctional epoxy siloxane monomers containing disiloxane, trisiloxane, and tetrasiloxane were prepared by hydrosilylation of an α,ω‐difunctional Si? H‐terminated siloxane with a vinyl‐functional epoxide. Cationic polymerization of these monomers using 3‐methyl‐2‐butenyltetramethylenesulfonium hexafluoroantimonate and their reactivities were examined. The reactivity order was disiloxane > trisiloxane > tetrasiloxane. Thermal discoloration of these polymers increased with catalyst concentration and also with the length of dimethyl siloxane. UV discoloration was also accelerated by catalyst. From the thermo gravimetric analysis, it was found that the thermal stabilities of polymers increased with increasing the length of dimethyl siloxane chain. Mechanical properties of polymers were also tested by thermal mechanical analysis and dynamic mechanical analysis, and it was found that the flexibility of polymers was increased with increasing siloxane chain length. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2010–2019, 2006     

Plasma Sprayed Coatings of High-Purity Ceramics for Semiconductor and Flat-Panel-Display Production Equipment

High-purity oxide ceramic powders of alumina (Al₂O₃) and yttria (Y₂O₃) have been developed to apply to semiconductor and flat-panel-display (FPD) production equipment. The ceramic coatings on the inside chamber wall of the equipment are required to have high erosion resistance against CFx plasma in dry etching process for microfabrications of the devices. It is found that the yttria coating formed from agglomerated-and-sintered powder consisting of large primary particles has smoother eroded surface with high erosion resistance. Considering the particle deposition on the devices, this coating will be effective in decreasing generation of large-sized particles, which easily deposit on the devices. Electric insulating properties of the coatings are also investigated to apply to electrostatic chuck. Electric breakdown voltage of yttria coatings is comparable to that of alumina coatings. Smaller powder is effective for improving the electric properties, and the influence of coating purity is lower than that of the powder size.     

Selectivity of alkali metal ion and lithium isotopes on ion exchangers prepared from MTi0.5Zr1.5(PO4)3(M = Li, Na)

Inorganic ion exchangers, H-TZP(Li) and H-TZP(Na), in the hydrogen form have been prepared by ion exchange from the precursors, LiTi_0.5Zr_1.5(PO₄)₃ and NaTi_0.5Zr_1.5(PO₄)₃, respectively. The degrees of leaching of lithium and sodium ions were 99.7% and 68%, respectively. No substantial difference in ion exchange property was observed between the two ion exchangers. Both showed high selectivity toward lithium and sodium ions, while rubidium and cesium ions showed low affinity among alkali metal ions. Isotopically, they were ⁶Li-specific like other inorganic ion exchangers so far examined. The ⁷Li-to-⁶Li isotopic separation factor, S, was found of 1.023 to 1.025 in acidic conditions at 25°C and nearly unity in highly basic conditions (pH 12 or higher). The latter S value was consistent with the formation of new ion exchange sites with low isotope selectivity of lithium.     

Characterization of multilayer films of Ti---Al---O---C---N system prepared by pulsed d.c. plasma-enhanced chemical vapor deposition

TiAlN/TiN, TiAlCN/TiAlN/TiN and TiAlON/TiAlN/TiN multilayer films were prepared on steel substrates by pulsed d.c. plasma-enhanced chemical vapor deposition (PECVD) at 823 K using gas mixtures of TiCl₄, AlCl₃, H₂, N₂, CH₄, O₂ and Ar. We studied the structural, compositional, mechanical and chemical properties of these films. Fracture cross-sections of the TiAlN and TiAlCN films showed columnar structure. On the other hand, those of the TiAlON films showed amorphous-like dense structure. X-Ray diffraction (XRD) analyses showed that the TiAlN, TiAlCN and TiAlON films had NaCl structure. The XRD peaks of the TiAlON films were broad. Glow discharge optical emission spectroscopy (GDOS) analyses proved that these films had multilayer structure. The Vickers hardness of the TiAlN/TiN, TiAlCN/TiAlN/TiN and TiAlON/TiAlN/TiN multilayer films were 2608, 2815 and 1444 Hv, respectively. These multilayer films had higher oxidation resistance and better tribological properties than the TiN single-layer films. The TiAlCN/TiAlN/TiN multilayer films showed the best wear resistance. Furthermore, these multilayer films demonstrated superior corrosion resistance in a molten aluminum alloy at 953 K. The TiAlON/TiAlN/TiN multilayer films indicated the best corrosion resistance.     

Effect of addition of Ag on the microstructures and electrical properties of sol-gel derived SnO2 glass composites

The effect of addition of Ag on the microstructure and electrical properties of sol-gel derived SnO₂-glass composites was examined. Comparisons of the microstructures and electrical properties were carried out between glass composites prepared by a sol-gel method and a conventional one using glass frit. The glass composite gels and the SnO₂-glass powder mixtures containing AgNO₃ were calcined at 500 °C in order to decompose AgNO₃ into Ag and then fired at 900 °C. In the sol-gel derived glass composites, the grain growth of Ag was suppressed and Ag particles connected mutually at the boundaries of aggregated gel particles to form three-dimensional networks. Thus, the glass composite derived by the sol-gel method showed a high electrical conductivity and a positive temperature coefficient of resistance (TCR). The highly electrical conductive paths of Ag in the glass composite were effectively formed when powder compacts were formed at a higher pressure. On the other hand, in the glass composites prepared using SnO₂-glass powder mixtures, coarse-grained Ag particles were isolated in closed pores regardless of the forming pressure, and therefore did not contribute to electrical conduction in the glass composite.     

Effect of Nd and Pr addition on the thermal and mechanical properties of (U, Ce)O2

The thermal conductivity, Young’s modulus, and hardness of (U_0.65−xCe_0.3Pr_0.05Nd_x)O₂ (x = 0.01, 0.08, 0.12) were evaluated and the effect of Pr and Nd addition on the properties of (U, Ce)O₂ were studied. The polycrystalline high-density pellets were prepared with solid state reactions of UO₂, CeO₂, Pr₂O₃, and Nd₂O₃. We confirmed that all Ce, Pr, and Nd dissolved in UO₂ and formed solid solutions of (U, Ce, Pr, Nd)O₂. We revealed that the thermal conductivity of (U_0.65−xCe_0.3Pr_0.05Nd_x)O₂ (x = 0.12) was up to 25% lower than that of x = 0.01 at room temperature. The Young’s modulus of (U_0.65−xCe_0.3Pr_0.05Nd_x)O₂ decreased with x, whereas the hardness values were constant in the investigated x range.     

Tunneling currents in In0.53Ga0.47As homojunction diodes and design of InGaAs/InP hetero-structure avalanche photodiodes

Tunneling currents in InGaAs homojunctions were studied from measurements of temperature dependence of breakdown voltage, current-voltage characteristics, tunneling effective mass, and noise spectrum. Zener emission dominates the reverse current prior to avalanche breakdown in the carrier concentration region of >10¹⁵ cm^?3 and restricts the avalanche gain in InGaAs homojunctions. An InGaAs/InP hetero-structure having a p-n junction in the InP layer was studied to reduce dark currents caused by Zener emission. A design chart to aid in the realization of a high performance APD is discussed.     

Stereoselective Covalent Adduct Formation of Acyl Glucuronide Metabolite of Nonsteroidal Anti-Inflammatory Drugs with UDP-Glucuronosyltransferase

A reactive metabolite of nonsteroidal anti-inflammatory drugs (NSAIDs), acyl-β-D-glucuronide (AG), covalently binds to endogenous proteins. The covalent adduct formation of NSAIDs-AG may lead to the dysfunction of target proteins. Therefore, it is important to clarify the detailed characterization of the formation of covalent protein adducts of NSAID-AG. UDP-glucuronosyltransferase (UGT) catalyzes the conversion of NSAIDs to NSAIDs-AG. The aim of this study was to perform a quantitative analysis of the covalent adduct formation of NSAIDs-AG with UGT. Diclofenac-AG and ketoprofen-AG formed covalent adducts with organelle proteins. Next, the number of covalent adducts formed between NSAIDs-AG and UGT isoforms (UGT1A1, UGT1A9, UGT2B4, and UGT2B9) was determined. The capacity of diclofenac-AG to form covalent adducts with UGT1A9 or UGT2B7 was approximately 10 times higher than that of mefenamic acid-AG. The amounts of covalent adducts of AG of propionic acid derivative NSAIDs with UGT2B were higher than those with UGT1A. Stereoselectivity was observed upon covalent binding to UGT. A significant negative correlation between the half-lives of NSAIDs-AG in phosphate buffers and the amount of covalent adduct with UGT2B7 was observed, suggesting the more labile NSAID-AG forms higher irreversible bindings to UGT. This report provides comprehensive information on the covalent adduct formation of NSAIDs-AGs with UGT.     

Output power enhancement of a palmtop terahertz-wave parametric generator

Broadband terahertz (THz) waves were generated by optical parametric processes based on laser light scattering from the polariton mode of a nonlinear crystal. By using the parametric oscillation of a MgO-doped LiNbO3 crystal pumped by a nanosecond Q-switched Nd:YAG laser, we have realized a broadband, high-energy and compact THz-wave source. We report the development of a THz-wave parametric generator (TPG) using a small pump source with a short pulse width and a top-hat beam profile. These characteristics of the pump beam permit high-intensity pumping especially close to the output surface of the THz wave without thermal damage to the crystal surface. We also calculated the outcoupled THz wave for beams with two different intensity profiles: a top-hat beam (in this experiment) and a Gaussian beam (previously reported). The result shows the mechanism of the output energy and/or power enhancement.