Solution copolycondensation of isophthalic acid,terephthalic acid, 4,4′‐dihydroxydiphenylsulfone,and bisphenols with a tosyl chloride/dimethylformamide/pyridine condensing agent

The solution polycondensation of a mixture of various parts of isophthalic acid (IPA) and terephthalic acid (TPA) with 4,4′‐dihydroxydiphenylsulfone (BPS) with tosyl chloride/dimethylformamide/pyridine as a condensing agent was studied. To elucidate how the reaction should be done to obtain copolymers of high molecular weights, we examined the two‐stage copolycondensation with BPS and 2,2‐bis(4‐hydroxyphenyl)propanes (BPAs) by changing the content of IPA/TPA and the amount of BPS or BPA used in the initial reaction. Controlling the reaction at an earlier stage could facilitate the copolycondensation. The polyesters of IPA/TPA and BPS of moderate inherent viscosity values up to 1.0 were obtained by the two‐stage reaction with optimal amounts of BPS first and then additional BPS. Satisfactory results were also obtained by the dropwise addition of BPS over 10–20 min in the preparation of the IPA/TPA–BPS polymers containing less than 50 mol % TPA. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2607–2610, 2002     

In situ SAXS analysis of extended-chain crystallization during melt-drawing of ultra-high molecular weight polyethylene

Phase development during melt-drawing of ultra-high molecular weight polyethylene (UHMW-PE) was analyzed by in situ small-angle X-ray scattering measurements using synchrotron radiation at the SPring-8. Films with different entanglement characteristics were prepared by solution blending of higher and lower MW samples with a viscosity average MW of 1.07 × 10⁷ (higher) and 1.73 × 10⁶ (lower), followed by compression molding at 180 °C. Independent of blend ratio, the strong streak attributed to extended-chain crystals (ECCs) appeared on the equator at the beginning point of the plateau stress region in the stress profile, which was one of the characteristic features of melt-drawing. A series of detailed analyses of these streaks suggested that two components with different dimensions were formed during melt-drawing: one was a precursory ECC, and the other was a mature ECC. These two ECC components grew synchronously at the beginning point of the plateau stress region for both films, independent of the entanglement characteristics of the film. However, the time of this synchronized growth was longer for the film with the lower MW component than for the film containing only the higher MW component. The resultant morphologies of the melt-drawn samples observed by transmission electron microscopy also reflected these characteristics. These results demonstrate that molecular entanglement characteristics dominate the unique crystallization mechanism that forms ECCs with different dimensions during melt-drawing of UHMW-PE.     

Apatite-Forming Ability of Sodium-Containing Titania Gels in a Simulated Body Fluid

An essential condition for an artificial material to bond to living bone is the formation of bonelike apatite on its surface in the living body. The bonelike apatite can be reproduced on the bone-bonding material even in an acellular simulated body fluid (SBF) with ion concentrations almost equal to those of human blood plasma. In the present study, the dependence of the apatite-forming abilities of sodium-containing titania gels in a SBF on composition and structure is examined. The sodium-containing titania gels are model substances produced on the surface layer of bioactive titanium metal prepared by sodium hydroxide solution and heat treatments. When sodium-containing titania gels are immersed in the SBF, Na⁺ ions incorporated in the gels are exchanged with the H₃O⁺ ions in the SBF. This ion exchange causes an accompanying increase in the pH of the SBF and increases its ionic activity product, thus providing favorable conditions for apatite nucleation on the surfaces of the gels. Nevertheless, sodium-containing titania gels that do not contain anatase do not form apatite on their surfaces. Independent of the composition, the gels form apatite on their surfaces in the SBF, specifically when they contain anatase. These results imply that the Ti-OH groups on titania, which have been proposed to be responsible for the apatite formation, are effective for apatite nucleation when they are arranged in a specific structural unit based on the anatase structure.     

从微观组织世界看钢铁材料的魅力

从钢中的原子扩散、相变等基础理论,形成各种组织导致其强度等性能发生变化的微观现象,解说了钢铁材料何以能复盖宽范围强度水平,从而在多种领域获得应用,具备其它金属材料所没有的独特魅力。     

Effect of chain structure on the melt rheology of modified polypropylene

The effect of molecular structure of polypropylene (PP) on the melt rheological properties were investigated for electron irradiated polymer and di-2-ethylhexyl peroxy dicarbonate (EHPC)-treated polymer. The modifications were examined in terms of the rheological behaviors, molecular weight distribution, and the degree of branching. The high melt strength PP was obtained by irradiating with 50 and 80 kGy and adding EHPC. The modified PPs showed the strain hardening in the uniaxial elongational viscosity, though the linear elongational viscosity was lower than that of the unmodified PP. Low angle laser light-scattering measurements of the modified PPs showed the interesting results; high irradiation doses such as 50 and 80 kGy caused higher molecular weight chains branching. Nevertheless, the long branching chains were not detected for the EHPC modified PP, which also showed the strain hardening in uniaxial elongational flow. In this article, the relation between chain structure and rheological properties is discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1493–1500, 1999     

Transient performance analysis of a six-phase pole change induction motor for electric vehicles

We previously proposed a six-phase pole change induction motor (six-phase PCIM) for electric vehicles (EVs), and have presented its operating principle and steady state characteristics. The six-phase PCIM expands the constant power operation range using the pole change technique without mechanical contactors; therefore it possesses superb characteristics for miniaturizing EV driving systems. This paper proposes a new analysis method for the six-phase PCIM in order to derive basic equations which can be used to analyze transient phenomena caused by pole change and to create control methods. First, a “six-phase tensor-transformed rotational d-q axis” is defined and its physical meaning made clear. By using this axis, voltage and torque equations which can uniformly deal with the steady state and transient states will be derived. Next, we compare measured and simulated results of voltage, current, and torque characteristics in steady state and in transient states at the pole change operation and both-pole dual operation. Through these comparisons, the validity of our theory and its effectiveness to performance analysis and application to the control method for the six-phase PCIM is discussed in detail. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120(2): 59–71, 1997     

Proteolytic degradation of myofibrillar components by carp cathepsin L

Carp cathepsin L, which is the best candidate to produce textural change in the arai-treated carp fillet, exhibited maximum hydrolytic activity for Z-Phe-Arg-MCA and soluble casein at pH 5·0–5·5. The proteolytic action of the enzyme was evaluated by complete degradation of various carp myofibrils at pH 5·0 over 30 min and by potent degradation of the same proteins at pH 5·5–6·0 over 20 h. All myofibrillar components were partially degraded by the enzyme at pH 6·5–7·0, but varying amounts of them remained undegraded after 20 h. These findings indicate that carp cathepsin L degrades not only carp myofibrillar components but also their resultant products between pH 5·0 and 7·0 and that it markedly acts on myosin heavy chain, α-actinin and troponin-T and -I. Carp cathepsin L likely contributes to postmortem muscle tenderisation of carp fillet over an extensive pH range during storage. © 1998 SCI.     

UPGRADING OF COAL-DERIVED LIQUIDS. 1. CATALYTIC ACTIVITIES OF ZEOLITE CATALYSTS AND COMMERCIAL HDS CATALYSTS

ABSTRACT

The applicability of various zeolite catalysts and commercial HDS catalysts to the secondary hydrotreatment of coal-derived liquids was examined in relation to the chemical structure of upgraded liquids. The catalytic activities of zeolite catalysts for HI conversion is lower than are the activities of Ni-Mo, Ni-Co-Mo, Co-Mo and Ni-W catalysts. However, as regards hydrogenation and the removal of nitrogen, zeolite catalysts such as natural clinoptilolite and mordenite have almost the same activity as do Co-Mo and Ni-W catalysts. As to the removal of oxygen, it was proved that zeolite catalysts had a functionality to remove oxygen as COx gas, and HDS catalysts had a high activity for hydrodeoxygenation.     

Preparation of polydimethylsiloxane/polystyrene interpenetrating polymer network membranes and permeation of aqueous ethanol solutions through the membranes by pervaporation

Polydimethylsiloxane (PDMS)/polystyrene (PSt) interpenetrating polymer network (IPN) membranes were prepared by the bulk copolymerization of styrene and divinylbenzene in the PDMS networks. The interpenetration of PDMS and PSt resulted in the improvement of mechanical properties of PDMS. Transmission electron microscope (TEM) observation demonstrated that the PDMS/PSt IPN membranes have microphase-separated structures consisting of a continuous PDMS phase and a discontinuous PSt phase. When an aqueous ethanol solution was permeated through the PDMS/PSt IPN membranes by pervaporation, the PDMS/PSt IPN membranes exhibited ethanol permselectivity, regardless of the PDMS content. The effects of their microphase-separated structures on the permeability and selectivity for aqueous ethanol solutions are discussed experimentally and theoretically. © 1996 John Wiley & Sons, Inc.