The Experts below are selected from a list of 172824 Experts worldwide ranked by ideXlab platform
Hideki Yamane - One of the best experts on this subject based on the ideXlab platform.
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higher order structures and mechanical properties of bacterial homo poly 3 hydroxybutyrate fibers prepared by cold drawing and annealing processes
Polymer, 2004Co-Authors: Yukiko Furuhashi, Yoshitaka Imamura, Yohei Jikihara, Hideki YamaneAbstract:Abstract Pure bacterial homo poly(3-hydroxybutyrate) (PHB) fibers were prepared by melt spinning, followed by cold-drawing in an amorphous state at a temperature just above its glass transition temperature. Cold drawn fibers obtained were further drawn at higher temperatures, followed by annealing at various temperatures under tension. Relations among the processing conditions, higher order structures and mechanical properties were investigated using wide- and small-angle X-ray diffractions (WAXD and SAXD, respectively), birefringence, differential scanning calorimetry (DSC), and tensile measurements. PHB has two different Crystalline Forms, 2 1 helix conFormation (α-Form) and planar zigzag conFormation (β-Form). A single broad reflection of β-Form was detected even in a PHB fiber drawn once at a temperature just above its T g immediately after quenching and it tended to be stronger after 2nd drawing at higher temperatures. Annealing under low temperature and high tension facilitates the occurrence of β-Form. It is suggested that the β-Form Crystal is Formed not only from the tie chains between α-Form lamella, but also from completely free amorphous chains. Changes in the amount of two types of Crystals were analyzed using the WAXD integrated intensity. Birefringence of these fibers shows negative and positive values, depending on process conditions. Changes in higher order structure on the mechanical properties are also discussed.
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Enzymatic degradation of bacterial homo-poly(3-hydroxybutyrate) melt spun fibers
Polymer, 2001Co-Authors: Hideki Yamane, K. Terao, Shigehiro Hiki, Yutaka Kawahara, Yoshiharu Kimura, Terumi SaitoAbstract:The effect of the higher order structure on the degradation behavior of bacterial homo-poly(3-hydroxybutyrate) (PHB) melt spun fibers by a PHB depolymerase from Commamonas testosteroni was investigated. After the enzymatic degradation, fibrillar structure remained at the surface of the drawn and annealed fibers, while a spongy structure appeared in the as-spun fiber. Similar spongy structure to the degraded as-spun fiber was observed in the core part of some drawn and annealed fibers after the fibrillar surface disappeared. The mechanical properties deteriorated as enzymatic degradation proceeded. After the amorphous region was degraded, β-Form Crystal, which seems to have less ordered structure, degraded in advance to the α-Form Crystal as revealed by WAXS measurements. However, these tendencies were less pronounced for the fiber annealed at high temperature under high tension. This result suggests that the β-Form Crystal in the fiber annealed at high temperature under high tension would have more ordered Crystalline structure, which withstands against the attack by the enzyme.
Soon Man Hong - One of the best experts on this subject based on the ideXlab platform.
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piezoelectric properties of poly vinylidene fluoride and carbon nanotube blends β phase development
Physical Chemistry Chemical Physics, 2009Co-Authors: Soon Man HongAbstract:In order to get poly(vinylidene fluoride) (PVDF) films containing high β-phase content, multiwalled carbon nanotubes (MWCNTs) were blended with PVDF. For drawn samples, the content of piezoelectric β-Form Crystal was increased with MWCNT addition due to the rapid Crystallization rate offered by the nucleating action of MWCNT, but soon reached a plateau. Poling on the drawn samples helps additional β-phase Formation when the added MWCNT content was less than 0.2 wt%; at this MWCNT amount, almost pure β-phase Crystal was obtained. More MWCNT addition induced depolarization to reduce the β-phase content. Undrawn samples show monotonous increase of β-phase content with MWCNT amount when subjected to poling.
Matsuo Hirami - One of the best experts on this subject based on the ideXlab platform.
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Intrinsic Birefringence of γ-Form Crystal of Nylon 6: Application to Orientation Development in High-Speed Spun Fibers of Nylon 6
Macromolecular Materials and Engineering, 2001Co-Authors: Shigemitsu Murase, Matsuda Tsunetoshi, Matsuo HiramiAbstract:The intrinsic birefringences of the α- and the γ-Form Crystals of nylon 6 were calculated from the atomic coordinates and the bond polarizabilities using the Lorentz-Lorenz equation. The intrinsic birefringence of the γ-Form Crystal was found to be significantly smaller than that of the α-Form Crystal. Those values were applied to the evaluation of the orientation function of the amorphous phase of the nylon 6 fibers produced by the high-speed spinning process. The molecular orientation in the amorphous phase increased to the maximum point and then decreased with the spinning speed. These results suggested that an inhomogeneous structure in the fiber was Formed for the higher take-up speed.
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Structure and properties of high‐speed spun fibers of nylon 6
Macromolecular Chemistry and Physics, 1997Co-Authors: Shigemitsu Murase, Masaru Kashima, Kazushige Kudo, Matsuo HiramiAbstract:Structure and properties of high-speed spun fibers of nylon 6 were studied in the range of take-up speeds from 5 to 12 km/min. With increasing take-up speed, Young's modulus increased uniFormly, while tenacity passed through a maximum at 8 km/min. WAXD data demonstrated the increase in the perfectness of the Crystalline state with increasing take-up speed. First, the γ-Form Crystal structure predominated up to 9 km/min along with increase in its Crystal size; second, in the range of 9 to 12 km/min, the a-Form Crystal structure appeared and developed as reflected by the increase in its Crystal perfection. The structure-properties relationships are discussed, and it is indicated that the increasing tendency of Young's modulus over 9 km/min can be attributed to the development of the a-Form Crystals.
Hong Wu - One of the best experts on this subject based on the ideXlab platform.
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improvement of physical properties of palm stearin and soybean oil blends by enzymatic interesterification and their application in fast frozen food
RSC Advances, 2017Co-Authors: Yali Zhao, Minhua Zong, Xia Zhang, Bing Li, Hong WuAbstract:In order to obtain good quality special fats for fast frozen food, blends of palm stearin (PS) and soybean oil (SO) (5 : 5, 6 : 4 and 7 : 3, PS : SO) were subjected to enzymatic interesterification in a fluidized bed reactor. The slip melting point of the interesterified blends thus obtained was 45 °C when the flow rates were 2.24, 1.57 and 0.40 mL min−1, respectively. After interesterification, the contents of SSS- and UUU-type TAGs decreased, whereas the contents of SUU-type TAGs increased. In addition, the β Form Crystal reduced and β′ Form Crystal increased due to the change in the type of TAGs. The solid fat content of the interesterified blends was 5–40% at 10–45 °C. The results of sensory evaluation indicated that the special fats prepared from the interesterified blends had better quality when they were applied in the preparation of fast frozen dumplings. Hence, enzymatic interesterification is promising in preparing high-quality special fat for fast frozen food.
Xia Liao - One of the best experts on this subject based on the ideXlab platform.
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Effect of cosolvent on solid phase transitions of α‐ to β‐Form Crystal of syndiotactic polystyrene occurred in supercritical Co2 containing solvent
Journal of Polymer Science Part B: Polymer Physics, 2007Co-Authors: Xia Liao, Jun ZhangAbstract:The solid phase transition mechanism of α- to β-Form Crystal upon specific treating with supercritical CO2 + cosolvent on original pure α and mixed (α+β) Form syndiotactic polystyrene (sPS) was investigated, using wide angle X-ray diffraction and differential scanning calorimetry measurements as a function of temperature, pressure, and cosolvent content. As in the supercritical CO2, sPS in supercritical CO2 + cosolvent underwent solid phase transitions from α- to β-Form, and higher temperature or higher pressure favored this transFormation. Due to the higher dipole moment of acetone, small amounts of acetone used as cosolvent with CO2 made the transition of α- to β-Form occur at lower temperature and pressure than in supercritical CO2, and made the α-Form Crystal completely transForm to β-Form in the original mixed (α+β) Form, whereas ethanol did not. The original β-Form Crystal in the original mixed (α+β) Form sample acted as the nucleus of new β-Form Crystal in the presence of cosolvent as it did in supercritical CO2, when compared with the original pure α-Form sample. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1625–1636, 2007
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Process analysis of phase transFormation of α to β-Form Crystal of syndiotactic polystyrene investigated in supercritical CO2
Polymer, 2005Co-Authors: Xia LiaoAbstract:Mechanism of solid phase transFormation of a to b Form Crystal of syndiotactic polystyrene (sPS) was investigated in supercritical CO2. The phase transFormation occurred in the original pure a and mixed (aCb) Form sPS in supercritical CO2 was traced as a function of temperature and pressure by means of wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC). At appropriate temperature and pressure, sPS underwent solid phase transitions from a to b Form. Higher temperature or higher pressure favored this transFormation. Compared to the original pure a Form sample, the original b Form Crystal in the mixed (aCb) Form sample acted as the nucleus of b Form Crystal, so that reduced the transition temperature and pressure. q 2005 Elsevier Ltd. All rights reserved.