Considerations on detailed analysis and particle growth in high impact polypropylene particles

Detailed analysis of the dispersion of ethylene and propylene copolymer components in high‐impact polypropylene particles was performed by the morphological observation, pore volume analysis, and microscopic Fourier transform infrared spectroscopy of SPring‐8. The results of the morphological observation and pore volume distribution suggest that copolymer components were formed in particles in such a manner as to fill the gaps of fine homopolypropylene particles. The results of the analysis by microscopic Fourier transform infrared spectroscopy were that the distribution of the amount of ethylene in the particles was homogeneous and indicated that copolymer components were dispersed uniformly within the particles. Moreover, spots with high amounts of ethylene were formed on the particle surface, and when voids existed within the particle, spots with high amounts of ethylene were also formed on the void surface. The structure of the copolymer components existing locally on the surface was practically similar to the structure of the copolymer components within the particles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Injection-molded plastic plate with hydrophobic surface by nanoperiodic structure applied in uniaxial direction

The purpose of this research is to establish a processing method for a wide-area nanometer scale periodic structure on the surface of a plastic plate in order to improve its hydrophobicity. We also evaluated the effect of a nanoperiodic structure applied in the uniaxial direction. Plastic plates of acrylonitrile–ethylene–styrene with dimensions of 100 × 100 mm² with a nanoperiodic structure on their surfaces were fabricated using a femtosecond laser and an injection molding technique. In the injection molding, the maximum transfer ratio for the depth reached as high as 0.79. When the nanoperiodic structure was applied in the uniaxial direction, the apparent contact angles did not decrease with respect to the direction of the ridges. As a result, the apparent contact angle increased by 20.4°, from 77.2° to 97.6° which is equivalent to 26%. In the six-month duration test, the sliding angle was initially decreased by applying the nanoperiodic structure. Additionally, the sliding angle was maintained between 20° and 38.3° during the duration test, which was lower than the angle for the flat plate at 42.7°. It can be considered that the depth was sufficient to maintain the sliding angle. In this condition, the contact angle hysteresis did not differ with or without the nanoperiodic structure on the surfaces, an effect that could be caused by surface dirt. In summary, the plastic plate was well drained and the characteristics were maintained for several months by forming the nanoperiodic structure on the surface.     

Synthesis and properties of novel poly(tetramethylsilnaphthylenesiloxane) derivatives

Novel poly(tetramethylsilnaphthylenesiloxane) derivatives were synthesized and characterized by differential scanning calorimetry (DSC), thermogravimetry (TG), and X-ray diffraction analyses. Poly(tetramethylsilnaphthylenesiloxane) derivatives were obtained by condensation polymerization of the corresponding disilanol derivatives, i.e. 1,4-, 1,5-, 2,6-, and 2,7-bis(dimethylhydroxysilyl)naphthalenes, which were prepared by the Grignard reaction using chlorodimethylsilane and the corresponding dibromonaphthalene derivatives followed by the hydrolyses, catalyzed by palladium on charcoal. The obtained poly(tetramethyl-1,5-silnaphthylenesiloxane) was insoluble in common organic solvents; however, the other polymers exhibited the good solubility in common organic solvents, such as tetrahydrofuran (THF), chloroform, dichloromethane, and toluene. The introduction of tetramethyl-1,5-silnaphthylenesiloxane units into the resulting polymer was confirmed by ¹H NMR spectrum of the copolymer obtained by condensation copolymerization of 1,5-bis(dimethylhydroxysilyl)naphthalene with 1,4-bis(dimethylhydroxysilyl)naphthalene. It was revealed from the DSC and X-ray diffraction measurements that poly(tetramethyl-1,5-silnaphthylenesiloxane) and poly(tetramethyl-2,6-silnaphthylenesiloxane) exhibited the crystallinity; however, poly(tetramethyl-1,4-silnaphthylenesiloxane) and poly(tetramethyl-2,7-silnaphthylenesiloxane) were amorphous. The glass transition temperature (T_g) and the temperature at 5% weight loss (T_d5) of poly(tetramethylsilnaphthylenesiloxane) derivatives with dimethylsilyl group at 1-position of the naphthylene moiety were higher than those at 2-position of the naphthylene moiety. The T_g and melting point (T_m) of the present polymers were higher than those of poly(tetramethyl-1,4-silphenylenesiloxane).     

Nanocellular foams—cell structure difference between immiscible and miscible PEEK/PEI polymer blends

Plastic foam with a nanoscale cell structure was prepared from poly(ether ether ketone) (PEEK)/para‐diamine poly(ether imide) (p‐PEI) as well as PEEK/meta‐diamine poly(ether imide) (m‐PEI) blends by a temperature quench foaming method with CO₂. The difference in chemical configuration between m‐ and p‐PEI gave rise to a prominent change in the higher order blend morphology and cell structure of the respective foams. The bubble nucleation site and bubble size were controlled by templating the morphology of the PEEK/p‐PEI blend, which shows an immiscible and unique strip‐patterned crystalline morphology. The properties influenced by the immiscibility of the PEEK/p‐PEI blend were investigated using SEM, thermal analysis and rheology and compared with the properties of the miscible PEEK/m‐PEI blend. The bubble size and location were highly controlled in the PEI disperse domain that was aligned between the PEEK crystalline layers in the PEEK/p‐PEI blend. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Application of compatible dual‐echo arteriovenography in stroke: Preliminary observations

Compatible dual‐echo arteriovenography (CODEA) is a recent MRI technique for simultaneous acquisition of an MR angiogram (MRA) and MR venogram (MRV) with image quality comparable to conventional single‐echo acquisitions. The purpose of this study was to evaluate the utility of CODEA in imaging patients with chronic stroke and to test the utility of a new image representation technique (“enhanced maximum intensity projection [MIP]") based on tissue segmentation, intensity inversion, and vessel enhancement filtering) for MRV. Arterial and venous abnormalities associated with stroke were delineated on MRA and MRV acquired simultaneously with the CODEA technique. CODEA MRV displayed with the enhanced MIP technique facilitated the visualization of the overall venous structures in 3D. Reduced venous vascularity was detected in the regions of arterial occlusion compared to the contralateral normal brain regions. The CODEA technique along with the enhanced MIP technique may be valuable, particularly in clinical applications that require efficient MRA/MRV imaging because of limited scan time such as in acute stroke. © 2013 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 23, 152–156, 2013     

Cytocompatibility and mechanical properties of novel porous 316 L stainless steel

Novel 316 L stainless steel (SS) foam with 85% porosity and an open pore diameter of 70–440 μm was developed for hard tissue application. The foam sheet with a 200-μm diameter had superior cell proliferation and penetration as identified through in vitro experiments. Calcification of human osteosarcoma cells in the SS foam was observed. Multi-layered foam preparation is a potential alternative technique that satisfies multi-functional requirements such as cell penetration and binding strength to the solid metal. In tensile tests, Young's modulus and the strength of the SS foam were 4.0 GPa and 11.2 MPa respectively, which is comparable with human cancellous bone.     

Development of a Thermal Buffering Device to Cope with Temperature Fluctuations for a Thermoelectric Power Generator

To stabilize the heat input to a thermoelectric generator (TEG) and protect it from large temperature fluctuations, a thermal buffering device (TBD) was fabricated and examined using a typical Bi-Te TEG module and a brand-new Mg₂Si TEG module. The TBD comprises two adjoining heat storage containers, each containing different alloys, which can be optimized for the temperature range of the TEG. The combination of two alloys in series diminishes the thermal fluctuations, stabilizing the heat input to the TEG module. This is achieved by having two metallic materials with large enthalpies of fusion that can be placed between the heat source and the TEG. The combination of the two alloys can be optimized for the temperature ranges of Bi-Te, Pb-Te, or Co-Sb. For the Bi-Te TEG, 15Al-85Zn and 30Sn-70Zn alloys were used for the heat source side and the TEG side, respectively. The corresponding alloys for the Mg₂Si TEG were 20Ni-80Al and 7Si-93Al. With the use of a TBD, the Bi-Te TEG exhibited no notable damage even in the rather high temperature range beyond ??573?K. For the Mg₂Si TEG, no operational damage of the Mg₂Si TEG module was observed even with a temperature of 1020?K.     

Intracavity second-harmonic generation at 320 nm of an actively Q-switched Pr:LiYF4 laser

We demonstrate pulse laser operation of a Pr:LiYF(4) laser pumped by InGaN laser diodes (444 nm) using an acousto-optic modulator. We obtained a maximum laser peak power of 167 W (4 μJ/pulse) with a pulse width of 24 ns at an 11 kHz repetition rate for a 63 nm wavelength. Employing an 8 mm long lithium triborate nonlinear crystal in the laser cavity, we obtained a maximum peak power of 55 W (2.7 μJ/pulse) at 320 nm, which corresponds to a conversion efficiency of 69% with respect to the fundamental laser energy. The UV laser pulse width was 36 ns.