Synthesis and properties of novel side-chain-sulfonated polyimides from bis[4-(4-aminophenoxy)-2-(3-sulfobenzoyl)]phenyl sulfone

A novel side-chain-sulfonated aromatic diamine of bis[4-(4-aminophenoxy)-2-(3-sulfobenzoyl)]phenyl sulfone (BAPSBPS) was synthesized. Sulfonated copolyimides were synthesized by random and sequenced block copolymerization of 1,4,5,8-naphthalene tetracarboxylic dianhydride, BAPSBPS and nonsulfonated diamine. They displayed good solubility in common aprotic solvents and high desulfonation temperature of 350 °C, suggesting the high stability of sulfonic acid groups. The reduced viscosity was in the range of 0.4-1.8 dl/g at 0.5 g/dl and 35 °C. Flexible and tough membranes with reasonably high mechanical strength were prepared. They showed anisotropic membrane swelling with larger swelling in thickness than in plane. They displayed reasonably high proton conductivity (σ), taking their lower ion exchanging capacity (IEC) into account. For example, the membrane with IEC of 1.54 mequiv/g showed σ values of 81 and 11 mS/cm in water and 70% RH, respectively, at 60 °C.     

Reaction of sodium perborate with a chlorinated cyclic hindered amine (TMP-Cl): I. Quantitative evaluation of active oxygen species in fabric bleaching

The reaction of N-chloro-4-hydroxy-2,2,6,6-tetramethylpiperidine (TMP-Cl) with sodium perborate (PB) was investigated with special reference to the generation of singlet oxygen and the possible application to a new oxidative bleaching process. Generation of the singlet oxygen (¹O₂), the hydroxyl radical (HO·) and superoxide anion radical (O₂·⁻) in the PB/TMP-Cl mixed solution was confirmed by the trapping reagent method. From the results of another experiment, in which the bleaching abilities of each active oxygen species were confirmed, the main active oxygen species contributing to the bleaching of purpurogallin, the skeleton of black tea pigment, in the PB/TMP-Cl system was concluded to be¹O₂.     

Studies on the biaxial stretching of polypropylene film. XI. Type II orientation during [2-2FI]-type stretching and its change by subsequent thermal contraction

In order to study the deformation mechanism of type II stretching, the change in orientation during the restretching and subsequent thermal contraction was investigated by x-ray diffraction method. When a uniaxially oriented film is restretched, the lamellae which are stacked in the stretching direction by the stretching rotate as a whole toward the restretching axis. They rotate backward nearly reversibly during the thermal contraction, unless the restretching exceeds a balancing state, where the orientation in the film plane are equal in all directions. However, when the restretching degree is so high and the film orientation exceeds the balancing state, the lamellar rotation is accompanied by a complex phenomenon. It is considered from the wide-angle and small-angle x-ray diffraction patterns that the lamellar surface becomes indented because of slippage between microfibrils composing the lamellae, and the microfibrils themselves bend at the boundary between the amorphous and crystalline regions within which the tilting of c-axis also occurs. Upon contracting of the film; these changes recover, but even in the last stage of contraction the orientation approaches the symmetrical biaxial orientation but not the uniaxial orientation from which the biaxial orientation is started. These orientation and disorientation behaviors are not affected basically by a slight change in the restretching temperature and the degree of stretching.     

An Application of Silica‐Based Monolithic Membrane Emulsification Technique for Easy and Efficient Preparation of Uniformly Sized Polymer Particles

Summary: Uniformly sized polymer particles were prepared by an emulsification and polymerization technique utilizing a silica monolithic membrane, namely the “silica monolithic membrane emulsification technique”. In this paper, we utilized silica monolithic membrane as a device for the preparation of uniformly sized polymer particles. A mixture of monomers, diluents and oil‐soluble initiator was emulsified into a continuous medium through the silica monolithic membrane and polymerized. The particles obtained had a higher size uniformity than that of particles prepared by previously reported membrane emulsification techniques, such as the Shirasu Porous Glass (SPG) emulsification technique. Through the silica monolithic membrane emulsification technique, we could prepare particles having availability as a possible packing material for solid‐phase extraction (SPE) and high performance liquid chromatography (HPLC).

SEM photograph of silica particles prepared through capillary plate membrane.     

Structural characterization of 1,2-polybutadiene by 13C-n.m.r. spectroscopy: 2. Sequence distribution of 1,2-unit in hydrogenated polybutadienes

The configurational sequences of 1,2-unit in a series of hydrogenated syndiotactic 1,2-polybutadienes were determined in relation to the sequence distribution of 1,2- and 1,4-units on the basis of the ¹³C-n.m.r. signal assignment of the methyl carbons. The observed triad distributions of 1,2- and 1,4-units and configurational distributions of the 1,2-unit are in good agreement with the calculated distributions from transition probabilities. The number average sequence lengths of the 1,2-unit and the 1,2-unit in the racemic addition are 5.7 to 8.0 and 4.1 to 5.4, respectively. From the extrapolation of the plot of the number average sequence length against the crystallinity of the starting 1,2-polybutadienes, the minimum sequence length for crystallization is estimated to be 3.7 for the 1,2-unit in the racemic addition.     

Negative ion etching of Al−Si−Cu by employing a magnetic filter in halogen plasmas

Al etching was studied employing negative ions generated in downstream Cl₂ plasma. The Al etch rate by the alternate irradiation of positive and negative ions was two times higher than that by usual positive ions. In order to etch the Al film practically on an insulator covered electrode coupled with RF power, reduction of the negative self bias voltage (Vdc) was examined using a magnetic filter which traps electrons. The reason for the high etching reactivity is that the dominant negative ions F in SF₆ and Cl⁻ in Cl₂ plasmas are atomically very similar to the radicals. Addition of SF₆ and H₂ to a Cl₂/BCl₃ mixture reduced Vdc significantly. However, fluorine and hydrogen atoms inhibited Al etching in spite of sufficient ion energy.     

Pressure effects on the low temperature state of the α-(BEDT-TTF)2MHg(SCN)4 organic conductor family

Systematic magnetotransport measurements as a function of hydrostatic pressure have been made on four members of the α-(BEDT-TTF)₂MHg(SCN)₄ organic conductor family (M = K, Tl, Rb, NH₄). Applied pressure above about 6 Kbar removes the density wave state for M = K, Tl, and Rb. For M = NH₄ the superconducting state is removed with pressure as dT_c/dP = − 0.25 K/Kbar. In all cases the Shubnikov de Haas oscillation frequency increases with pressure, including the β orbit (which involves the entire Brillouin zone), and new orbits involving very small fractions of the Fermi surface are formed.     

Evolution of patinas on copper exposed in a suburban area

Copper plates were exposed under sheltered outdoor conditions for up to one year, starting in September 2001 in Musashino City, Tokyo, a suburban area. Following various periods of exposure, the patinas on the plates were characterized to investigate their evolution by using X-ray fluorescence analysis, X-ray diffraction, field emission scanning electron microscopy, and glow discharge optical emission spectroscopy. The difference in the roles of sulfur and chlorine in the early stages of copper patination were identified by analyzing the depth profiles of these two elements. Sulfur was found on top of the patina as cupric sulfates such as posnjakite (Cu₄SO₄(OH)₆ · H₂O) or brochantite (Cu₄SO₄(OH)₆). Brochantite appeared only after 12 months of exposure. In contrast, chlorine was found on the surface after only one month of exposure. It gradually penetrated the patina as the exposure period lengthened, forming copper chloride complexes. Chloride ions accumulated at the patina/copper interface, forming nantokite (CuCl), which promoted corrosion.     

Differences between corrosion products formed on copper exposed in Tokyo in summer and winter

We analyzed the copper corrosion products that formed during a month in summer and a month in winter at three sites in Tokyo using several analytical techniques. The X-ray diffraction patterns revealed that cuprite Cu₂O and posnjakite Cu₄SO₄(OH)₆·H₂O formed on copper exposed in summer. By contrast, only cuprite was found in winter exposed copper. The X-ray fluorescence results indicated that the amounts of sulfur and chlorine on the copper plates exposed in summer were much greater than those in winter. This could be explained by the change in particulate sulfate and sea salt concentrations. Depth profiling analysis by Auger electron spectroscopy revealed that the oxide layer formed in summer was thicker than that in winter. This difference in oxide layer thickness could have been due to the differences in temperature, relative humidity, and the amount of sulfur and chlorine on the copper plate.     

Microstructure Control of Thermally Sprayed Co-Based Self-Fluxing Alloy Coatings by Diffusion Treatment

This article describes microstructure control aimed for wear-resistance improvement of Co-based (Co-Cr-W-B-Si) self-fluxing alloy coating by diffusion treatment. The diffusion treatments of thermally sprayed Co-based self-fluxing alloy coating on steel substrate were carried out at 1370-1450 K for 600-6000 s under an Ar gas atmosphere. Microstructural variations of the coating and the interface between the substrate and the coating were investigated in detail. A proper diffusion treatment precipitates two kinds of fine compounds in Co-based matrix. X-ray diffractometer (XRD) and electron probe microanalyzer (EPMA) analysis revealed these precipitates to be a chromium boride dissolving cobalt and a tungsten boride containing cobalt and chromium. The size of each precipitate became larger with increasing treatment temperature and time. A coating with the proper size borides showed a superior wear-resistance. This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain Montavon, Ed., ASM International, Materials Park, OH, 2007.