Growth of Mg2TiO4 single crystals by the floating zone method

Single crystals of the peritectic compound Mg₂TiO₄ up to 8 mm diameter and 80 mm long along the [1 0 0] and [1 1 1] directions, were grown by the travelling solvent float zone (TSFZ) technique using a halogen lamp image furnace. The optimum conditions were as follows: sintering temperature of the charge rod, 1500° C, the growth rate, 2 mm h^–1 and the composition of the charge rod in molar ratio, MgOTiO₂=21.01. The chemical composition of the solvent zone was determined by application of the EPMA technique and the peritectic nature of Mg₂TiO₄ was proved. The refractive index of the grown crystal was 2.05.     

耐火浇注料白华现象的原因研究

为了解决耐火浇注料的白华现象,分别以不同原料与铝酸钙水泥配料实验。实验结果表明,某些原料对浇注料施工体的白华现象起到了促进作用,通过合理选择原材料及采取一些措施,可以避免和抑制白华现象的发生。     

Polar–polar interaction between the reinforcement and matrix for kevlar fiber-reinforced composite: Effect of using the blend of polar polymers as matrix

For the purpose of investigating the polar–polar interaction between reinforcement and matrix in polymer composite, the mechanical dispersions were studied for the composite comprised of the Kevlar fiber and poly(hydroxy ether of bisphenol A) (I), with which poly(ethylene oxide) (II) or poly(ethylene adipate) (III) was blended as a part of matrix. It is shown by analyzing the storage modulus and loss modulus vs. temperature curves that the reinforcement–matrix interaction is increased relatively to the primary transition temperature of matrix by blending II or III with I, and II is more efficient for increase of the interaction than III. The results obtained from the mechanical dispersions do not contradict those from the Fourier transform infrared spectra on the matrix-polymer-coated Kevlar fiber and on the mixture of matrix polymers with benzanilide, which is used as a model compound for the Kevlar fiber.     

Porous-microelectrode study on Pt/C catalysts for methanol electrooxidation

We have developed a porous-microelectrode (PME) to investigate the electroactivity of catalyst particles for proton exchange membrane fuel cells. The cavity at the tip of the PME was filled with Pt/C catalysts prepared by impregnation method. Cyclic voltammograms (CVs) recorded in 1 N H₂SO₄ aqueous solution revealed that the active area of the stacked catalysts exist not only at the surface but also inside of the stack. For methanol electrooxidation, 30 wt.% Pt/C exhibited the highest electroactivity, whereas the 50 wt.% Pt/C showed extremely small current. The small current is considered as a result of a small active-surface area. Methanol oxidation peak potential shifted toward cathodic direction as Pt-loading decreased, which agrees well with the Pt-oxide formation potential. The activation energy for methanol oxidation was assessed to be 44±3 kJ mol⁻¹ for all Pt/C catalysts and Pt-disc electrode.     

Syntheses of poly(methyl methacrylate)/poly(dimethyl siloxane) graft copolymers and their surface enrichment of their blend with acrylate adhesive copolymers

Several types of poly(methyl methacrylate)/poly(dimethyl siloxane) graft copolymers (PMMA‐g‐PDMS) were synthesized using macromonomer technology. Three types of PMMA‐g‐PDMS with different PDMS chain length were obtained. The effect of siloxane chain length on surface segregation of PMMA‐g‐PDMS/poly(2‐ethylhexyl acrylate‐co‐acrylic acid‐co‐vinyl acetate)[P(2EHA‐AA‐VAc)] blends was investigated. The blends of PMMA‐g‐PDMS with P(2EHA‐AA‐VAc) showed surface segregations of PDMS components. The surface enrichments of PDMS in the blends depended on the PDMS chain length, significantly. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1736–1740, 2002     

Creep-fatigue life evaluation for weldments of modified 9Cr-1Mo steel at boiler temperatures

Creep-fatigue tests were conducted to verify long-term structural integrity for weldments of modified 9Cr-1Mo steel at boiler plants. As a result, it was proved that the weldments were fractured mainly at the HAZ and the fatigue lives were reduced by strain hold. This appeared to be due to acceleration of crack initiation by creep strain concentration and acceleration of crack growth by void generation in the HAZ. A method for predicting the life is proposed based on the fracture mechanism, and its accuracy was confirmed to be within a factor of two.     

Beyond classical theory: Predicting the free energy barrier of bubble nucleation in polymer foaming

Based on the Gibbs‐Tolman‐Koenig formalism, we considered the Tolman correction to the free energy barrier of bubble nucleation in polymer‐gas binary mixtures. For this class of systems, the correction may be estimated with a reasonable accuracy using experimentally accessible macroscopic thermodynamic quantities only. Although the Tolman correction is applicable only in the low supersaturation regime, a simple ansatz regarding the supersaturation dependence of the Tolman length can be made to extend the usefulness of this approach and to yield the free energy barrier that vanishes at the mean‐field spinodal as demanded by thermodynamic considerations. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3042–3053, 2013     

Development of the chitosan tube prepared from crab tendon for nerve regeneration

Microstructure of a joint between a Pb–Sn eutectic solder and an electroless Ni–8 mass% P has beenexamined using transmission electron microscopy. Four layers, i.e. Ni₃Sn₄, Ni₄₈Sn₅₂, Ni₂SnP and Ni–20 mass% P, are formed between the solder and the electroless Ni–8 mass% P. Among them, Ni₄₈Sn₅₂ and Ni₂SnP were found for the first time in a solder joint. Spherical voids are formed at the interface between Ni₄₈Sn₅₂ and Ni₂SnP, and columnar voids are formed at the interface between Ni₂SnP and Ni–20 maas% P. From the analysis of the migration of the respective interfaces observed during in situ heatingexperiments, it is concluded that these voids are Kirkendall voids formed due to the difference in diffusivity of Ni across the interfaces. Fracture takes place at either of those interfaces during a dropping test.     

Effects of addition of functionalized SEBS on rheological,mechanical, and tribological properties of polyamide 6 nanocomposites

The effects of the addition of styrene‐ethylene/butylene‐styrene copolymer (SEBS) with various functionalized groups on the rheological, mechanical, and tribological properties on polyamide 6 nanocomposite filled with layered silicate (PA6/Clay) were investigated. Four types of SEBS: unmodified SEBS (SEBS), maleic anhydride grafted SEBS (SEBS‐g‐MA), amine group grafted SEBS (SEBS‐g‐NH₂), and carboxyl group grafted SEBS (SEBS‐g‐COOH) were added with PA6/Clay nanocomposite to prepare various polymer blends. These polymer blends were extruded by a twin screw extruder and injection molded. Dynamic viscoelastic properties of these blends in the molten state and their tensile, impact, and tribological properties were evaluated. The viscoelastic properties were found to increase with the addition of SEBS and were highly influenced by the types of functionalized groups contained. Influence of the addition of SEBS on the mechanical properties of these systems differed for each mechanical property. Although the tensile properties decreased with SEBS, Izod impact properties improved with the addition of various functionalized SEBS. These mechanical properties and viscoelastic properties correlated closely with the size of dispersed SEBS particles and interparticle distance. The tribological properties also improved with the addition of SEBS, and the influence of the amount added was higher than the type of SEBS used. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers