Crystal orientation of β-phase isotactic polypropylene induced by magnetic orientation of N,N′-dicyclohexyl-2,6-naphthalenedicarboxamide

Melt crystallization of isotactic polypropylene (iPP), containing crystallites of N,N′-dicyclohexyl-2,6-naphthalenedicarboxamide (DCNDCA) as a nucleating agent of the the β-phase iPP crystal, is carried out under a magnetic field (6 T) to obtain the alignment of the iPP crystal induced by magnetic alignment of DCNDCA. In a previous paper, DCNDCA was reported to undergo magnetic alignment in a liquid suspension. The obtained iPP sample exhibits alignment of the β-phase crystal with the c-axis aligned perpendicular to the magnetic field. The comparison of this alignment of iPP with the reported magnetic alignment of DCNDCA indicates that the β-phase crystal grows epitaxially on the DCNDCA crystal. The (330)_β plane of the iPP crystal lies on the bc-plane of the DCNDCA crystal in which the direction of the c-axis of the iPP coincides with the direction of the b-axis of the DCNDCA crystal.     

Sintering of Confined Silica in Oxidized Silicon Particles

We observed electron-beam-induced sintering of amorphous silica in oxidized submicrometer silicon particles and analyzed the nature of mass transport in linear and triangular particle assemblies. The movement of silica around the rigid crystalline cores occurs rapidly and fills the necks, but the relative core positions in the sintered product depends on the initial geometry of the confined oxide. However, a thin layer of silica remains stable against the flow.     

D.s.c. investigation of the states of water in poly(vinyl alcohol-co-itaconic acid) membranes

The state of water in water-swollen poly(vinyl alcohol-co-itaconic acid) membranes, having various water contents from 0.31 to 0.83, was investigated by d.s.c. measurements and compared with those in water-swollen poly(vinyl alcohol) membranes. The amount of freezing water in the membranes was estimated by use of a relationship between the phase transition temperature and the enthalpy of the crystallization of supercooled water. The melting temperature of the water in the membranes immersed in urea and NaCl 0–2 mol l^?1 aqueous solutions was also determined by d.s.c. analysis. The present study proposes a method for estimating the solubilities of urea and NaCl in both of the freezing and the non-freezing water using the melting point depression of the freezing water in the membranes immersed in the solute solution.     

Toughening of cycloaliphatic epoxy resins by poly(ethylene phthalate) and related copolyesters

Poly(ethylene phthalate) (PEP) and poly(ethylene phthalate–co‐ethylene terephthalate) were used to improve the brittleness of the cycloaliphatic epoxy resin 3,4‐epoxycyclohexylmethyl 3,4‐epoxycyclohexane carboxylate (Celoxide 2021?), cured with methyl hexahydrophthalic anhydride. The aromatic polyesters used were soluble in the epoxy resin without solvents and effective as modifiers for toughening the cured epoxy resin. For example, the inclusion of 20 wt % PEP (MW, 7400) led to a 130% increase in the fracture toughness (K_IC) of the cured resin with no loss of mechanical and thermal properties. The toughening mechanism is discussed in terms of the morphological and dynamic viscoelastic behaviors of the modified epoxy resin system. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 388–399, 2002; DOI 10.1002/app.10363     

Interdiffusion in Co-Mn alloys

Interdiffusion coefficient in cobalt-manganese alloys has been determined by Matano's method in the temperature range between 1133 and 1423 K on (pure Co)-(Co-30.28 at. pct Mn alloy) and (pure Co)-(Co-51.76 at. pct Mn alloy) couples. This, ∼D, has been found to increase with the increase of manganese content. However, the activation energy (∼Q) and frequency factor ( ₀) show a maximum at about 10 at. pct Mn. The concentration dependence of and has been discussed taking into account the thermodynamic properties of the alloy. The difference in between the ferro- and paramagnetic phases in Co-5 at. pct Mn alloy has been found to be 24 kJ/mol, which is larger, than that for the diffusion of Mn⁵⁴ in this alloy. Further it has been found that the Kirkendall marker moves toward manganese-rich side, showing that manganese atoms diffuse faster than cobalt atoms. From the marker shift, the intrinsic diffusion coefficients,D _Co andD _Mn, at 33 at. pct Mn have been determined as follows:D _Co=0.22×10⁻⁴ exp(−263 kJ mol⁻¹/RT) m²/s, andD _Mn=0.98×10⁻⁴ exp(−229 kJ mol⁻¹/RT) m²/s.     

Sintering mechanism of hydroxyapatite by addition of lithium phosphate

The sintering mechanism of hydroxyapatite (HAp) by addition of lithium phosphate (Li₃PO₄) has been investigated. Using the X-ray diffraction method, HAp was confirmed to decompose into -Ca₃(PO₄)₂ (-TCP) by addition of Li₃PO₄. The measurement of shrinkage rate by the isothermal firing made it clear that the densification process at the initial stage of sintering took place in the presence of liquid phase. Furthermore, the examination of the phase diagram on the binary system -TCP-Li₃PO₄ revealed that there was an eutectic point at 1010°C in the composition of 60 wt% Li₃PO₄. From these evidences, we concluded that -TCP produced by the decomposition of a part of HAp has formed the liquid phase by reacting with Li₃PO₄ above 1010°C, and that this liquid phase has largely promoted the densification by the rearrangement of HAp particles at the initial stage of sintering.     

Development of microphone leak detection technology on Fugen NPP

A method of leak detection, based on high-temperature resistant microphones, was originally developed in JNC to detect leakages with flow rates from 1 m³/h to 500m³/h. The development performed on Fugen is focused on detection of a small leakage at an early stage. Specifically, for the inlet feeder pipes the leak rate of 0.2gpm (0.046m³/h) has been chosen as a target detection capability. Evaluation of detection sensitivity was carried out in order to check the capability of the method to satisfy this requirement. The possibility of detecting and locating a small leakage has been demonstrated through the research.     

Electrical resistivity of Si3N4 ceramics with Yb2O3 additive

Si₃N₄ ceramics with excellent mechanical properties are used for heat dissipation substrates and so on. In order to improve their reliability and expand their application fields, it is desirable to understand and control the electrical properties of Si₃N₄ ceramics. In this study, the electrical resistivity of Si₃N₄ ceramics with Yb₂O₃ additive was investigated by applying various voltages at temperatures ranging from 25°C to 300°C. When Yb₂O₃ was added as a sintering aid to Si₃N₄ ceramics, a crystalline J-phase (Yb₄Si₂O₇N₂) was formed and their electrical resistivity was significantly lower than that of Y₂O₃ additive. The electrical resistivity of the Yb₂O₃-added ceramics decreased with an increase in temperature and applied voltage. Yb existed in multiple valence states, Yb²⁺ and Yb³⁺, in the Si₃N₄ ceramics and the decrease in the electrical resistivity can be attributed hopping conduction through the J-phase. The J-phase in the Si₃N₄ ceramics was observed to be continuous, and percolation analysis suggested that the J-phase formed an infinite cluster. Therefore, the decrease in the electrical resistivity of the Yb₂O₃-added Si₃N₄ ceramics was found mainly to result from the formation of an infinite cluster of J-phase, which exhibits hopping conduction.     

Effects of processing and cooking on the levels of pesticide residues in soybean samples

The effects of processing and cooking on the levels of pesticide residues in soybean samples were investigated for 14 pesticides in pre-harvest samples. On soaking, the transfer ratios (%, total pesticide residue amount in product/that in soybean) of soaked soybean were greater than 60% for most of the pesticides investigated. The transfer ratio of soymilk ranged from 37% to 92%, and that of tofu ranged from 7% to 63%. The processing factor (Pf, the concentration (mg/kg) of pesticide in product/that in soybean) of tofu ranged from 0.026 to 0.28. These values varied among pesticides. There was a high correlation between the log P(ow) and the transfer ratio of tofu. The test described here should be useful to obtain the transfer ratios of pesticide residues in processing and/or cooking steps.