44 results on '"Hideki Yamane"'
Search Results
2. Melt electrospinning: Electrodynamics and spinnability
- Author
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Hideki Yamane, Huaizhong Xu, and Masaki Yamamoto
- Subjects
Jet (fluid) ,Materials science ,Polymers and Plastics ,Astrophysics::High Energy Astrophysical Phenomena ,Organic Chemistry ,02 engineering and technology ,Bending ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Physics::Fluid Dynamics ,Surface tension ,Viscosity ,Quantum electrodynamics ,Materials Chemistry ,High Energy Physics::Experiment ,Elongation ,Composite material ,Deformation (engineering) ,0210 nano-technology ,Melt electrospinning ,Phase diagram - Abstract
The electrodynamics of the polymer melt as well as its effects on fiber spinnability in the framework of laser-heated melt electrospinning was investigated. We challenge the classic views in the aspects of the molten Taylor-cone, the thinning process, and the jet deformation. A temperature-voltage phase diagram was constructed to distinguish the regimes of the bending, the whipping, and the break-up of the jet. These jet kinematics are significantly dependent on the molten Taylor-cone, the jet thinning, and the forces exerted on the jet. The surface tension restricts the growth of the jet while it can be safely neglected after jet initiation. Jet breaks up periodically at the tip of Taylor-cone if the polymer viscosity is too low or the elongation rate is not high enough to stretch the jet. The elongation rate for each segment of the jet keeps almost constant at a certain melt temperature, while the elongation rate increases and the solidification point of the jet shifts from the Taylor-cone to the target with increasing melt temperature. An analytic equation is proposed to estimate the jet diameter along the spinline before jet solidifies. Additionally, the experiment of coiling proved that the electrical and the elastic as the dominant forces for bending are gradually replaced by the inertial and the viscous forces for whipping.
- Published
- 2017
3. Thermal properties of the multi-stereo block poly(lactic acid)s with various block lengths
- Author
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Yoshiharu Kimura, Kazunari Masutani, Yohanes Windu Widhianto, Masaki Yamamoto, and Hideki Yamane
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Materials science ,Polymers and Plastics ,Analytical chemistry ,02 engineering and technology ,Atmospheric temperature range ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Amorphous solid ,law.invention ,Lactic acid ,chemistry.chemical_compound ,Lamella (surface anatomy) ,chemistry ,Mechanics of Materials ,law ,Block (telecommunications) ,Polymer chemistry ,Materials Chemistry ,Copolymer ,Hexamethylene diisocyanate ,Crystallization ,0210 nano-technology - Abstract
Multi-sb-PLAs with molecular weights of approximately 60,000 (MSB-60) and 130,000 (MSB-130) with various block lengths were synthesized. These have a structure in which di-block copolymers consisting of L - and D -blocks with the same length are connected with 1,12-dodecanediol (DMG), an initiator and hexamethylene diisocyanate (HMDI), a chain extender alternately. DSC analyses revealed that T g increases with the increase in the block length and the multi-sb-PLA with a lower molecular weight has higher T g at a constant block length. These are attributable to the higher concentration of DMG and HMDI in the multi-sb-PLA. T m increases with the increase in the block length and the molecular weight of multi-sb-PLA and those of MSB-60 and MSB-130 get close to a constant value at higher block length. The variation of T m seems to be attributable to change in the lateral dimension of lamella rather than that of the thickness. T c in the heating process from the amorphous solid decreases and that in the cooling process from the melt increases with the increase in the block length, indicating that the multi-sb-PLA with a long block has a wider temperature range of the crystallization.
- Published
- 2017
4. Effect of the block length and the molecular weight on the isothermal crystallization behavior of multi-stereoblock poly(lactic-acid)s
- Author
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Hideki Yamane, Yohanes Windu Widhianto, Kazunari Masutani, Masaki Yamamoto, and Yoshiharu Kimura
- Subjects
Materials science ,Polymers and Plastics ,Molecular mass ,Small-angle X-ray scattering ,Annealing (metallurgy) ,02 engineering and technology ,Atmospheric temperature range ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,law.invention ,Lactic acid ,Amorphous solid ,chemistry.chemical_compound ,Crystallography ,chemistry ,Mechanics of Materials ,law ,Materials Chemistry ,Lamellar structure ,Crystallization ,0210 nano-technology - Abstract
Multi-stereoblock PLAs (multi-sb-PLA)s having the controlled block sequences between PLLA and PDLA were synthesized by the chain-extension of tri-stereoblock PLAs. These multi-sb-PLAs only crystallize into the stereocomplex without forming any traces of homo-chiral crystal. The effects of the block length and the total molecular weight on the isothermal crystallization behavior and the higher order structure of the multi-sb-PLAs were investigated. Observation of isothermal crystallization behavior revealed that the multi-sb-PLA with longer blocks and higher molecular weights started the crystallization at a lower temperature within a shorter period of time in a wider temperature range. The crystallization rate increases with increasing block length and the multi-sb-PLA with a longer blocks achieves higher degree of crystal. The multi-sb-PLA with a higher molecular weight forms more complete structure of the spherulite than that with a low molecular weight. Annealing of the amorphous multi-sb-PLA produced sc with two different lamellar thicknesses. One which melts at a higher temperature is a main sc phase with a lamellar thickness merely determined by the block length and the molecular weight regardless of the thermal history. The chains in the amorphous region only crystallized upon annealing and gradually grew with increasing annealing temperature giving some addition to the lamellar thickness of the samples detected by SAXS.
- Published
- 2017
5. Green polymer chemistry: the biomimetic oxidative polymerization of cardanol for a synthetic approach to ‘artificial urushi’
- Author
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Shiro Kobayashi, Takumi Otsuka, Shun-ichi Fujikawa, and Hideki Yamane
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chemistry.chemical_classification ,Cardanol ,Polymers and Plastics ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Polymer engineering ,0104 chemical sciences ,chemistry.chemical_compound ,Monomer ,chemistry ,Polymerization ,Emulsion ,Polymer chemistry ,Materials Chemistry ,0210 nano-technology ,Prepolymer ,Curing (chemistry) - Abstract
The present article reports a new method for the synthesis of ‘artificial urushi’ using cardanol, a major ingredient of cashew nutshell liquid, as the starting monomer. Natural urushi sap is polymerized in a water-in-urushiol (w/o) emulsion system; here, we mimic this system for the polymerization of cardanol. The combination of a weak amine base and a weak carboxylic acid functions as efficient emulsifier. The polymerization of cardanol is carried out in a water-in-cardanol (w/o) emulsion to produce a prepolymer emulsion, which is further cured by crosslinking, resulting in the biomimetic polymerization of cardanol. The prepolymer emulsion is stable for storage. The films were prepared from the prepolymer emulsion; the curing of these films was achieved by thermal annealing or by cobalt naphthenate-catalyzed crosslinking in air to generate ‘artificial urushi’. The rheological properties of the cardanol monomer and the prepolymer emulsions resulted in excellent film formation on the substrate. Physical property examinations of the cured films showed sufficient hardness for use as a coating layer. Cardanol is a renewable resource, and no organic solvent was used, and thus, this polymerization is a green chemical process. A green method for the synthesis of ‘artificial urushi’ has been developed using cardanol, a main ingredient of cashew nutshell liquid, as the monomer via a reaction mimicking that of natural urushi. A water-in-cardanol (w/o) emulsion was developed by identifying a novel emulsifier, and polymerization of the cardanol emulsion generated prepolymer films, leading to polycardanol (artificial urushi) after curing with mechanical properties that are approximate to those of natural urushi coatings.
- Published
- 2016
6. Green polymer chemistry: One-pot, metal-free synthesis of macromonomer via direct polycondensation of lactic acid and its radical polymerization to graft and comb polymers
- Author
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Yui Yoshimura, Kiyoaki Ishimoto, Maho Arimoto, Misato Nojiri, Hideki Yamane, Shiro Kobayashi, Yuji Aso, and Hitomi Ohara
- Subjects
chemistry.chemical_classification ,Glycidyl methacrylate ,Condensation polymer ,Materials science ,Polymers and Plastics ,Organic Chemistry ,Radical polymerization ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Macromonomer ,01 natural sciences ,0104 chemical sciences ,Lactic acid ,Miniemulsion ,chemistry.chemical_compound ,chemistry ,Polymer chemistry ,Materials Chemistry ,Copolymer ,Organic chemistry ,0210 nano-technology - Abstract
A new and simple method of one-pot two-stage poly(lactic acid) (PLA) macromonomer synthesis has been developed. The first stage of the reaction is a direct polycondensation of lactic acid (LA) without a catalyst to PLA, and the second stage is a ring-opening addition of PLA to glycidyl methacrylate (GMA) to afford a PLA macromonomer with a methacryloyl polymerizable group (GMA-Macro). Both reactions are performed consecutively in one pot. This method produced GMA-Macro with high functionality in high yields and thus far seems the simplest and probably the cheapest way to prepare PLA macromonomers. Furthermore, the method is metal-free, offering considerable advantages for biomedical and pharmaceutical applications. GMA-Macro has been shown to be useful for the preparation of PLA graft copolymers in solution or in miniemulsion and of PLA comb polymers in solution. LA is a biobased renewable feedstock. Thus, this method provides a good opportunity to conduct ‘green polymer chemistry’.
- Published
- 2016
7. Regeneration of cellulose dissolved in ionic liquid using laser-heated melt-electrospinning
- Author
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Tilman Bronner, Masaki Yamamoto, Huaizhong Xu, and Hideki Yamane
- Subjects
Materials science ,Polymers and Plastics ,Organic Chemistry ,Regenerated cellulose ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Electrospinning ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,Cellulose fiber ,chemistry ,Chemical engineering ,law ,Ionic liquid ,Materials Chemistry ,Fiber ,Crystallization ,Cellulose ,0210 nano-technology ,Melt electrospinning - Abstract
A “green” and highly efficient route was proposed to fabricate ultrafine cellulose fibers. The processing steps include cellulose dissolution, gel preparation, melt-electrospinning and fiber coagulation. High DP cellulose can be easily dissolved in 1-butyl-3-methylimidazolium chloride (BmimCl) when the blend was stirred at 110 °C for 2 h. The maximum solubility can reach up to 16.7 wt%. A homogeneous ternary cellulose/BmimCl/ethanol or cellulose/BmimCl/water gel was made by the methods of crystallization and casting for the purpose of fixing the shape of the cellulose/BmimCl solution. After laser-heating and electrospinning, multiple jets were ejected from the gel tip and then frozen on a super cold target. Pure cellulose fibers without beads and blocks were achieved after coagulation. The results of WAXD and FTIR indicated that the regenerated cellulose fibers were amorphous and chemically stable. More importantly, this approach can be applied to other polysaccharides for the preparation of ultrafine fibers.
- Published
- 2018
8. Competitive Effects of Stereocomplexation and Hyper-Conjugation of Triethoxysilyl-Terminated Poly(<scp>d</scp> -lactide) in Poly(<scp>l</scp> -lactide) matrices
- Author
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Hideki Yamane, Yoshiharu Kimura, and Jungyub Hyun
- Subjects
Condensation polymer ,Lactide ,Materials science ,Polymers and Plastics ,Hydrosilylation ,General Chemical Engineering ,Organic Chemistry ,technology, industry, and agriculture ,Casting ,chemistry.chemical_compound ,Silanol ,Hydrolysis ,chemistry ,Polymerization ,Polymer chemistry ,Materials Chemistry ,Particle - Abstract
Triethoxysilyl-terminated poly(d-lactide)s (eSi-PDLA) were successfully prepared by hydrosilylation of allyl-terminated PDLAs (A-PDLA-ac) which were readily prepared by ring-opening polymerization of d-lactide and the following terminal protection by acetylation. Their acid-catalyzed hydrolysis produced hyper-conjugated PDLAs with terminal silanol coupling. Blend PLLA films containing eSi-PDLA (Mn = 2.1 kDa) in 5-25 wt.% were successfully prepared by the solution casting method. The blend films were found to take a nano-porous or micro-phase separation structure, being different from that of the blend PLLA films containing trimethoxysilyl-terminated poly(d-lactide) (mSi-PDLA) which exhibited particle distribution structure. This difference was reasonably attributed to the different rate of hydrolytic polycondensation of the trimethoxy- and triethoxy-silyl terminals. These results revealed that the competing sterecomplexation/ hyper-conjugation/phase separation can afford specific morphologies, allowing fine control of properties.
- Published
- 2015
9. Isothermal crystallization kinetics of talc-filled poly(lactic acid) and poly(butylene succinate) blends
- Author
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Hitomi Ohara, Kazunori Fujii, Weraporn Pivsa-Art, Yuji Aso, Keiichiro Nomura, and Hideki Yamane
- Subjects
Materials science ,Morphology (linguistics) ,Polymers and Plastics ,Kinetics ,Nucleation ,02 engineering and technology ,010402 general chemistry ,Talc ,01 natural sciences ,law.invention ,chemistry.chemical_compound ,Crystallinity ,law ,Polymer chemistry ,Materials Chemistry ,medicine ,Crystallization ,Organic Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Lactic acid ,Polybutylene succinate ,Chemical engineering ,chemistry ,0210 nano-technology ,medicine.drug - Abstract
Blends comprising poly(lactic acid) (PLA), poly(butylene succinate) (PBS), and talc were prepared via a solution casting method. The weight ratios of PLA to PBS (PLA/PBS) blends were 80:20 and 60:40, whereas the talc content was varied from 0 to 5.0 parts per hundred resin (phr). The crystallization halftime (t 1/2) of PLA/PBS (80:20) at 80 °C was higher than those of neat PLA, PBS, and PLA/PBS (60:40); this is due to its high PLA content. The t 1/2 value for neat PLA at 90 °C decreased when the talc content was increased, whereas the value for neat PBS gradually increased. These phenomena can be seen more clearly at 95 and 100 °C. This means that talc not only promotes PLA crystallization but also acts as a crystallization inhibitor for PBS. The isothermal crystallization kinetics and spherulitic morphology of these samples were investigated. The extent of talc loading showed a strong dependence on the isothermal crystallization rate and the extent of PLA crystallinity, whereas the contrary effect was observed for PBS due to the growth of large crystals. This suggests that talc not only promotes the crystallization of PLA but also inhibits the crystallization of PBS. The results are in agreement with the crystallization halftime and polarized optical microscopy analysis.
- Published
- 2016
10. Mechanical properties and higher-order structures of biaxially drawn bacterial poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanote] films
- Author
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Hideki Yamane, Jae-Chang Lee, Shinichi Sakurai, and Nobuki Kato
- Subjects
Materials science ,Polymers and Plastics ,Scattering ,General Chemical Engineering ,Organic Chemistry ,Young's modulus ,Spherulite (polymer physics) ,Compression (physics) ,Polymer engineering ,symbols.namesake ,Ultimate tensile strength ,Materials Chemistry ,symbols ,Perpendicular ,Composite material ,Elongation - Abstract
Bacterial poly(3-hydroxybutyrate-co-hydroxyhexanoate) (PHBH) biaxially oriented films were prepared by combination of the roll and biaxial drawing processes. Compression molded films, which consisted of large spherulite aggregation, were roll drawn up to ×1.4 and further biaxially drawn up to 3.0×3.0. The tensile modulus and the break elongation decreased while the tensile strength increased as the biaxial draw ratio increased. Biaxially drawn films showed two kinds of structures: one in which the c-axis was almost perpendicular to the film surface and the other in which the c-axis was at an incline compared to the normal film surface. The correlation among the processing conditions, higher-order structures, and mechanical properties was investigated using wide-angle X-ray diffraction, small-angle X-ray scattering, and tensile measurements. Open image in new window
- Published
- 2011
11. Fiber making directly from poly(tetrafluoroethylene) emulsion
- Author
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Daisuke Kitagawa, Yoshihito Takagi, Ahmed El Salmawy, Jae-Chang Lee, Takashi Wano, Hideki Yamane, and Shinichi Yagi
- Subjects
PTFE fiber ,business.product_category ,Materials science ,Polymers and Plastics ,Organic Chemistry ,Young's modulus ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,Emulsion ,Ultimate tensile strength ,Materials Chemistry ,symbols ,Die (manufacturing) ,Tetrafluoroethylene ,Fiber ,Deformation (engineering) ,Composite material ,business - Abstract
Poly(tetrafluoroethylene) (PTFE) fiber with a superior mechanical property was prepared directly from its emulsion by the novel manufacturing process. The PTFE emulsion turned into a paste when a high shear flow was applied and the paste was extruded through a nozzle into a strand consisting of fine PTFE particles. The diameter of the strand was reduced stepwise by applying the die-drawing process through a conical die at a low temperature. The strand was further die-drawn down at elevated temperatures into fine PTFE fibers with a highly oriented crystalline structure. The crystalline orientation factor of the PTFE fiber reached very close to unity. Although the fibers obtained have a very high tensile modulus, the tensile strength was not as high as that expected from the crystalline orientation, suggesting that the presence of some defects in the PTFE fiber formed in the instantaneous deformation.
- Published
- 2011
12. Electrospinning of Continuous Aligning Yarns with a ‘Funnel’ Target
- Author
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Amalina M. Afifi, Shigeyuki Nakano, Yoshiharu Kimura, and Hideki Yamane
- Subjects
Jet (fluid) ,business.product_category ,Materials science ,Polymers and Plastics ,General Chemical Engineering ,Organic Chemistry ,Nozzle ,Electrospinning ,Protein filament ,Bundle ,Orientation (geometry) ,Materials Chemistry ,Fiber ,Funnel ,Composite material ,business - Abstract
A new electrospinning set-up is described for continuous aligning of poly(L-lactide) yarn. It comprises a slowly rotating grounded `funnel' target and a winder placed right up to the funnel. A charged polymer jet is ejected from a nozzle. The electrospun fibers are first accumulated on the mouth plane of the funnel to form a web. The web is then pulled upward and guided to a winder on which twisted fibers are continuously wound as a bundle. Each filament of the bundle is slanted at about 45 relative to the collecting direction, and its average diameter is 6.0+/-1.9 mu m. The drawn fiber shows improved tensile properties as a result of the increased molecular orientation. The morphologies of the twisted fibers before and after drawing are compared.
- Published
- 2010
13. Fabrication of Aligned Poly(L-lactide) Fibers by Electrospinning and Drawing
- Author
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Amalina M. Afifi, Hideki Yamane, Yoshiharu Kimura, Hajime Nakajima, and Shigeyuki Nakano
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Materials science ,Fabrication ,business.product_category ,Polymers and Plastics ,Rotor (electric) ,General Chemical Engineering ,Organic Chemistry ,Rotational speed ,Electrospinning ,law.invention ,Synthetic fiber ,law ,Nanofiber ,Microfiber ,Materials Chemistry ,Fiber ,Composite material ,business - Abstract
A new target collector was designed for taking up aligned nanofibers by electrospinning. The collector consists of a rotor around which several fins were attached for winding electrospun filaments continuously in large amounts. The alignment of the nanofibers wound on the collector was affected by the electrospinning conditions, such as the needle-to-collector distance and the applied voltage, but not by the rotation speed of the collector. At a voltage of 0.5 kV · cm -1 , about 60% of the fibers were found to be aligned within an angle of ± 5° relative to the rotational direction of the collector. The fiber alignment was improved to 90% by drawing the fiber bundle 2-3 times at 110°C. The drawing was also effective for crystal orientation of the fibers as revealed by WAXD. The drawn fibers show improved mechanical properties.
- Published
- 2009
14. Higher-order structural analysis of bacterial poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanote] highly oriented films
- Author
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Akifumi Yasui, Yeonhwan Jeong, Hideki Yamane, Jae-Chang Lee, and Shinichi Sakurai
- Subjects
Diffraction ,Crystallography ,Materials science ,Planar ,Polymers and Plastics ,Scattering ,Small-angle X-ray scattering ,Organic Chemistry ,Materials Chemistry ,Perpendicular ,Ductility ,Normal ,Calendering - Abstract
Bacterial poly[( R )-3-hydroxybutyrate- co -( R )-3-hydroxyhexanoate] (PHBH) highly oriented films were prepared by the combination of roll and uniaxial drawing processes. The change in the higher-order structure of PHBH films was investigated by wide-angle X-ray diffraction (WAXD) and small angle X-ray scattering (SAXS). Extended films, which show superior mechanical properties and high ductility, have complicated structures. By roll extension, both deformed and undeformed spherulites co-exist, the former inclined to the direction perpendicular to the film surface. The latter were destroyed by further uniaxial extension. The tie-molecules between uniaxially oriented lamellae were extended and transformed to the β-form with a planar zig-zag conformation. Three kinds of structures, c -axis parallel to the uniaxial drawing direction, c -axis inclining to the normal vector of the film surface, and the β-form between lamellae, are intermingled in the film.
- Published
- 2008
15. The effect of poly(ethylene glycol) as plasticizer in blends of poly(lactic acid) and poly(butylene succinate)
- Author
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Hitomi Ohara, Weraporn Pivsa-Art, Yuji Aso, Keiichiro Nomura, Hideki Yamane, and Kazunori Fujii
- Subjects
Materials science ,Polymers and Plastics ,education ,macromolecular substances ,02 engineering and technology ,Polyethylene glycol ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,PEG ratio ,Ultimate tensile strength ,Polymer chemistry ,Materials Chemistry ,technology, industry, and agriculture ,Plasticizer ,food and beverages ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Surfaces, Coatings and Films ,Polybutylene succinate ,Lactic acid ,chemistry ,Chemical engineering ,Polymer blend ,Elongation ,0210 nano-technology - Abstract
The effect of polyethylene glycol (PEG) on the mechanical and thermal properties of poly(lactic acid) (PLA)/poly(butylene succinate) (PBS) blends was examined. Overall, it was found that PEG acted as an effective plasticizer for the PLA phase in these microphase-separated blends, increasing the elongation at break in all blends and decreasing the Tg of the PLA phase. Significant effects on other properties were also observed. The tensile strength and Young's modulus both decreased with increasing PEG content in the blends. In contrast, the elongation at break increased with the addition of PEG, suggesting that PEG acted as a plasticizer in the polymer blends. Scanning electron microscope images showed that the fracture mode of PLA changed from brittle to ductile with the addition of PEG in the polymer blends. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43044.
- Published
- 2015
16. A spiropyran-based X-ray sensitive fiber
- Author
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Takahiro Okabe, Wataru Sakai, Gaku Hatsukano, Yurika Miyamae, Kenji Kinashi, Hideki Yamane, Makoto Ozaki, Naoto Tsutsumi, Ryotaro Nakamura, and Kazuya Jimbo
- Subjects
Materials science ,Indoles ,Polymers ,Surface Properties ,Polyesters ,Composite number ,Analytical chemistry ,Phosphor ,Catalysis ,Photochromism ,chemistry.chemical_compound ,Materials Chemistry ,Benzopyrans ,Fiber ,Lactic Acid ,Particle Size ,Spiropyran ,business.industry ,X-Rays ,Metals and Alloys ,X-ray ,General Chemistry ,Nitro Compounds ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Polyester ,chemistry ,Ceramics and Composites ,Optoelectronics ,Particle size ,business - Abstract
This study attempted to visualize reversible X-ray radiation by using a poly-(l-lactic acid) (PLLA) composite fiber with an average diameter of 150 μm. The fiber contains photostimulable phosphor (PSP) BaFCl:Eu(2+) particles that are subsequently dyed with the photochromic spiropyran dye (1,3,3-trimethylindolino-6'-nitrobenzopyrylospiran) (6-nitro BIPS).
- Published
- 2015
17. Higher-order structures and mechanical properties of stereocomplex-type poly(lactic acid) melt spun fibers
- Author
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Naoko Yoshie, Hideki Yamane, Yukiko Furuhashi, and Yoshiharu Kimura
- Subjects
Crystal ,chemistry.chemical_compound ,Materials science ,Polymers and Plastics ,Chemical engineering ,chemistry ,Annealing (metallurgy) ,Melting temperature ,Organic Chemistry ,Polymer chemistry ,Materials Chemistry ,Amorphous solid ,Lactic acid - Abstract
Equimolar blend of poly( l -lactic acid) (PLLA) and poly( d -lactic acid) (PDLA) was melt spun into fibers and the relations among the processing conditions, crystalline structures, thermal properties, and mechanical properties were investigated. Drawing and annealing were performed in order to obtain fiber mainly consisting of the stereocomplex crystal phase. Fibers drawn at various temperatures exhibited either amorphous, highly oriented homo crystal, or the mixture of homo and stereocomplex with a fairly low orientation depending on the drawing temperature. Annealing of the drawn fibers at an elevated temperature higher than the melting temperature of homo crystal increased the stereocomplex content significantly. The fractions of the homo and the stereocomplex crystals strongly depended on the higher-order structure of the drawn fibers and the annealing temperature.
- Published
- 2006
18. Higher order structural analysis of stereocomplex-type poly(lactic acid) melt-spun fibers
- Author
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Yukiko Furuhashi, Yoshiharu Kimura, and Hideki Yamane
- Subjects
Birefringence ,Materials science ,Polymers and Plastics ,Annealing (metallurgy) ,Crystal structure ,Condensed Matter Physics ,Amorphous solid ,Lactic acid ,Crystal ,chemistry.chemical_compound ,Crystallography ,Synthetic fiber ,chemistry ,Materials Chemistry ,Physical and Theoretical Chemistry ,Melt spinning - Abstract
The higher order structure of stereocomplex-type poly(lactic acid) melt-spun fibers of an equimolar blend of poly(L-lactic acid) and poly(D-lactic acid) was analyzed with wide-angle X-ray diffraction (WAXD) and birefringence measurements. Two different crystalline structures were observed in the fibers: α-form homocrystals and stereocomplex crystals. The weight fractions of the two crystals were estimated with the WAXD integrated intensity data. The crystalline orientation factors were obtained from the WAXD measurements. Well-oriented homocrystals formed during a drawing process at the crystallization temperature of the homocrystal. Drawing above this temperature caused the stereocomplex crystal to be formed. The crystalline orientation tended to be lower with increasing drawing temperatures. Through the combination of the intrinsic birefringence and the fractions of the α-form homocrystals and stereocomplex crystals, the birefringence of the amorphous phase was evaluated. The amorphous birefringence stayed positive and decreased with increasing drawing temperature.
- Published
- 2006
19. Compression molding and melt-spinning of the blends of poly(lactic acid) and poly(butylene succinate-co-adipate)
- Author
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Keiichiro Nomura, Yuji Aso, Kazunori Fujii, Weraporn Pivsa-Art, Hitomi Ohara, Sommai Pivsa-Art, Kiyoaki Ishimoto, and Hideki Yamane
- Subjects
chemistry.chemical_classification ,Materials science ,Polymers and Plastics ,Compression molding ,Izod impact strength test ,General Chemistry ,Polymer ,Biodegradable polymer ,Surfaces, Coatings and Films ,Polybutylene succinate ,chemistry ,Ultimate tensile strength ,Materials Chemistry ,Heat deflection temperature ,Polymer blend ,Composite material - Abstract
Poly(lactic acid) (PLA) is a biobased polymer made from biomass having high mechanical properties for engineering materials applications. However, PLA has certain limited properties such as its brittleness and low heat distortion temperature. Thus, the aim of this study is to improve toughness of PLA by blending with poly(butylene succinate-co-adipate) (PBSA), the biodegradable polymer having high toughness. Polymer blends of PLA and PBSA were prepared using a twin screw extruder. The melt rheology and the thermal property of the blends were examined. Further the blends were fabricated into compression molded parts and melt-spun fiber and were subjected to tensile and impact tests. When the PBSA content was low, PBSA phase was finely dispersed in the PLA matrix. On the other hand, when the PBSA content was high, this minor phase dispersed as a large droplet. Mechanical properties of the compression molded parts were affected by the dispersion state of PBSA minor component in PLA matrix. Impact strength of the compression molded parts was also improved by the addition of soft PBSA. The improvement was pronounced when the PBSA phase was finely dispersed in PLA matrix. However, the mechanical property of the blend fibers was affected by the postdrawing condition as well as the PBSA content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41856.
- Published
- 2014
20. X-Ray and Electron Diffraction Study of Poly(p-dioxanone)
- Author
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Teruo Monno, Hideki Yamane, Yutaka Kawahara, Atsushi Nakayama, Yukiko Furuhashi, Tadahisa Iwata, and Yoshiharu Kimura
- Subjects
Materials science ,Polymers and Plastics ,Organic Chemistry ,X-ray ,Poly-p-dioxanone ,Crystal structure ,Isothermal process ,law.invention ,Crystallography ,Electron diffraction ,law ,X-ray crystallography ,Materials Chemistry ,Fiber ,Electron microscope - Abstract
Solution-grown lamellar crystals of poly(p-dioxanone) (PPDX) have been crystallized isothermally from butane-1,4-diol at 100°C. The crystal structure of PPDX has been determined by interpretation of X-ray fiber diagrams of PPDX fibers and electron diffraction diagrams of lozenge-shaped chain-folder lamellar crystals. The unit cell of PPDX is orthorbombic with space group P2 1 2 1 2 1 and parameters: a=0.970 nm, b=0.74 mm, and c (chain axis) = 0.682 nm. There are two chains per unit cell, which exist in an anti parallel arrangement.
- Published
- 2004
21. Higher order structures and mechanical properties of bacterial homo poly(3-hydroxybutyrate) fibers prepared by cold-drawing and annealing processes
- Author
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Hideki Yamane, Yoshitaka Imamura, Yukiko Furuhashi, and Yohei Jikihara
- Subjects
Birefringence ,Materials science ,Polymers and Plastics ,Annealing (metallurgy) ,Organic Chemistry ,Amorphous solid ,Crystal ,Differential scanning calorimetry ,Chemical engineering ,Ultimate tensile strength ,Polymer chemistry ,Materials Chemistry ,Melt spinning ,Glass transition - 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.
- Published
- 2004
22. Processing of a Strong Biodegradable Poly[(R)-3-hydroxybutyrate] Fiber and a New Fiber Structure Revealed by Micro-Beam X-Ray Diffraction with Synchrotron Radiation
- Author
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Akihisa Takeuchi, Yoshiharu Doi, Yoshio Suzuki, Tadahisa Iwata, Hideki Yamane, Yoshihiro Aoyagi, Kentaro Uesugi, and Masahiro Fujita
- Subjects
Diffraction ,Materials science ,Polymers and Plastics ,Annealing (metallurgy) ,Organic Chemistry ,X-ray ,Synchrotron radiation ,Crystallography ,Synthetic fiber ,Zigzag ,X-ray crystallography ,Ultimate tensile strength ,Materials Chemistry ,Composite material - Abstract
Biodegradable poly[(R)-3-hydroxybutyrate| (P(3HB)) fibers with high tensile strength of 1.32 GPa were processed from ultra-high-molecular-weight P(3HB) by a method combining cold-drawing and two-step-drawing procedures at room temperature. The distribution of molecular structures in a mono-filament was analyzed by micro-beam X-ray diffraction with synchrotron radiation. It was revealed that the P(3HB) fiber has a new core-sheath structure consistent with two types of molecular conformations: a 2 1 helix conformation in the sheath region and a planar zigzag conformation in the core region.
- Published
- 2004
23. Effect of steric hindrance on hydrogen-bonding interaction between polyesters and natural polyphenol catechin
- Author
-
Haruo Nishida, Jianchun Li, Bo Zhu, Hideki Yamane, Yong He, Yoshiharu Kimura, and Yoshio Inoue
- Subjects
Steric effects ,Polymers and Plastics ,Hydrogen bond ,Catechin ,General Chemistry ,Miscibility ,Surfaces, Coatings and Films ,Polyester ,chemistry.chemical_compound ,Differential scanning calorimetry ,chemistry ,Polymer chemistry ,Materials Chemistry ,Phenol ,Glass transition - Abstract
The phase behaviors for the blends of poly(3-hydroxypropionate) (PHP), poly(L-lactide) (PLLA), poly(D-lactide) (PDLA), and poly(D,L-lactide) (PDLLA) with catechin were investigated by differential scanning calorimetry. In PLLA/catechin, PDLA/catechin, and PDLLA/catechin blends, two glass transitions were detected when the catechin content was ≥40 wt %, whereas in PHP/catechin blends only one glass transition was observed over the whole range of blend compositions. The former and the latter results should reflect the inhomogeneous and the homogeneous nature of the blends, respectively, in the amorphous phase. These different phase behaviors should arise from the differences in the chemical structures between PHP and PLLA/PDLA/PDLLA, which dominates the strength and the number of intermolecular hydrogen-bonding interactions between the ester carbonyl groups of polyesters and the phenol groups of catechin. As detected by FTIR spectroscopy, in comparison with PHP, the steric hindrance of side-chain methyl groups of PLLA, PDLA, and PDLLA might restrain the formation of hydrogen bonds between their ester carbonyl groups and the phenol hydroxyl groups of catechin, even weakening the strength of such hydrogen bonds. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3565–3573, 2004
- Published
- 2004
24. Chemical Modification and some Aligned Composites of Chitosan in a Filament State
- Author
-
Yoshiharu Kimura, Kojiro Matsukawa, Hideki Yamane, Shigehiro Hirano, Min Zhang, and Masuo Nakagawa
- Subjects
Materials science ,Polymers and Plastics ,fungi ,technology, industry, and agriculture ,Chemical modification ,Fibroin ,Bioengineering ,macromolecular substances ,Sericin ,Biomaterials ,Protein filament ,Chitosan ,Hydrolysis ,chemistry.chemical_compound ,SILK ,chemistry ,Polymer chemistry ,Materials Chemistry ,Polymer blend ,Composite material ,Biotechnology - Abstract
The mono-filaments (> 10 m in length) of chitosan and the blends of chitosan-collagen, chitin-collagen and chitin-silk fibroin were wet-spun. The mono-filaments were chemically N-modified with each of n-fatty acid anhydrides, intra-molecular carboxylic anhydrides, fragrant aldehydes and transition metal ions. The mono-filament was aligned on a straight line with the mono-filament of silk fibroin or poly(ethylene terephthalate) (PET), and a bundle of one to three mono-filaments was coated with a medium of sericin (Se), chitosan or N-acylchitosan to give rise to novel silk-mimic filament composites. The filaments coated with a medium of sericin exhibited 26-27 denier for the titer, 2.46-3.36 gf.denier -1 for the tenacity and 11.8-25.0% for the elongation. The apparent density (denier.μm -1 in the filament diameter) of the filament composites was about 3-4 times higher than that of the mono-filaments. Portion of fragrant aldehydes in Schiff's base was slowly hydrolyzed at room temperature by contacting with atmospheric moisture in the open air, and released from the fragrant filaments and composites. The filament composites coated with a chitosan medium were thrombogenic, and those coated with N-acylchitosans were antithrombogenic.
- Published
- 2003
25. Effect of the addition of poly(d-lactic acid) on the thermal property of poly(l-lactic acid)
- Author
-
K. Sasai and Hideki Yamane
- Subjects
Materials science ,Polymers and Plastics ,Organic Chemistry ,Kinetics ,Nucleation ,law.invention ,Lactic acid ,Crystal ,chemistry.chemical_compound ,Chemical engineering ,chemistry ,law ,Thermal ,Polymer chemistry ,Materials Chemistry ,Molecule ,Crystallite ,Crystallization - Abstract
Thermal property and crystallization behavior of PLLA blended with a small amount of PDLA (1–5 wt%) were studied. PDLA molecules added in PLLA formed stereocomplex crystallites in the PLLA matrix. When the blend was cooled to a temperature below Tm of PLLA, stereocomplex crystallites acted as nucleation sites of PLLA and enhanced the crystallization of PLLA significantly (heterogeneous nucleation). Such crystallization enhancement was not observed when the blend with lower PDLA content was cooled from 240 °C at which both PLLA crystal and the stereocomplex disappeared. Low molecular weight PDLA isolated in the matrix of PLLA did not form a stereocomplex crystallite with a large surface area enough to act as a nucleation site. On the other hand, high molecular weight PDLA chains formed a large stereocomplex crystallite. With increasing PDLA content, stereocomplex crystallites were more easily formed and they acted as nucleation sites. PLLA crystal near the stereocomplex crystallites has an incomplete structure and showed a melting peak at a lower temperature than pure PLLA crystal.
- Published
- 2003
26. Effect of the melt-mixing condition on the physical property of poly(<scp>l</scp> -lactic acid)/poly(<scp>d</scp> -lactic acid) blends
- Author
-
Masaki Yamamoto, Yoko Fukui, Esraa El-Khodary, and Hideki Yamane
- Subjects
Materials science ,Polymers and Plastics ,Nucleation ,02 engineering and technology ,General Chemistry ,Transesterification ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,law.invention ,Lactic acid ,Physical property ,Crystal ,chemistry.chemical_compound ,Differential scanning calorimetry ,chemistry ,law ,Polymer chemistry ,Materials Chemistry ,Copolymer ,Crystallization ,0210 nano-technology - Abstract
The effect of the mixing condition in a mill-type mixer on the thermal property and the crystal formation of the poly(l-lactide)/poly(d-lactide) blends is investigated. The blends melt-mixed at 200 and 210 °C under application of a high shear flow tend to show a single melting peak of the stereocomplex crystal (SC) in the differential scanning calorimetry first and second heating processes without indicating the trace of the melting of homo-chiral crystal. The mixing at an elevated temperature causes a serious thermal degradation. Further kneading of the blends at an elevated temperature higher than Tm of SC causes the transesterification between the same enatiomeric chains forming block copolymers of l- and d-chains. This block copolymer acts as a nucleating agent of SC and the compatibilizing agent between poly(l-lactide) and poly(d-lactide) and promotes the formation of SC. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45489.
- Published
- 2017
27. Mechanical properties and higher order structure of bacterial homo poly(3-hydroxybutyrate) melt spun fibers
- Author
-
Hideki Yamane, K. Terao, Shigehiro Hiki, and Yoshiharu Kimura
- Subjects
Crystallography ,Materials science ,Polymers and Plastics ,Annealing (metallurgy) ,Stereochemistry ,Organic Chemistry ,Materials Chemistry ,Poly-3-hydroxybutyrate ,Molecule ,Orthorhombic crystal system ,Higher Order Structure ,High tension ,Amorphous solid - Abstract
Bacterial homo poly(3-hydroxybutyrate) (PHB) was melt spun into fibers and the relations among the processing conditions, crystalline structures, and the mechanical properties were investigated. WAXD patterns of PHB fibers indicate a broad reflection which cannot be assigned to any plane in the orthorhombic system of PHB, although most strong reflections can be assigned to the planes in the orthorhombic system. It has been reported that the broad reflection is assigned to be β-zigzag form, which occurs by the stretching of the amorphous tie molecules between lamellae. When annealed under high tension, this broad reflection tended to be stronger, while it became significantly weak when annealed without tension. These results suggest that the annealing without tension makes the amorphous tie molecules crystallized into orthorhombic form, while annealing under high tension makes the molecules in the amorphous region stretched and increased the fraction of the β-zigzag form.
- Published
- 2001
28. Dynamic interfacial properties of polymer blends under large step strains: shape recovery of a single droplet
- Author
-
R Hayashi, Hideki Yamane, Hiroshi Watanabe, Hiroshi Jinnai, and Masaoki Takahashi
- Subjects
Microscope ,Materials science ,Polymers and Plastics ,Geometry ,law.invention ,Physics::Fluid Dynamics ,Optics ,law ,Materials Chemistry ,chemistry.chemical_classification ,business.industry ,Organic Chemistry ,technology, industry, and agriculture ,Spheroid ,Polymer ,Ellipsoid ,shape recovery of droplet ,Shear (geology) ,chemistry ,immiscible polymer blend ,step strain ,sense organs ,Dumbbell ,Polymer blend ,business ,Shear flow - Abstract
We observed shape recovery of a deformed droplet in an immiscible polymer matrix under large step strains using stereo microscopes from two directions. On application of a large step strain, a soft spherical droplet in a matrix with higher viscosity deformed to a flat ellipsoid. The stretch ratio of major axis of the flat ellipsoid was 5/4 times larger than that predicted from the affine deformation. The flat ellipsoid changed into a rod-like shape and then to a dumbbell, to an ellipsoid of revolution, and finally back to the sphere. The orientation angle between the major axis and shear direction did not change during the course of this shape recovery and was independent of the initial radius of the droplet. The time needed for the whole shape recovery got longer as the initial radius and the strain were increased. For a given step strain, the normalized interfacial area plotted against the stretch ratio fell onto a master curve irrespective of the initial radius of the undeformed droplet. It is shown that the deformed droplet reforms to the sphere after it passes through various shapes by reducing the interfacial area.
- Published
- 2001
29. Characterization of chemical and solid state structures of acylated chitosans
- Author
-
Z Zong, Hideki Yamane, Masaoki Takahashi, and Yoshiharu Kimura
- Subjects
chemistry.chemical_classification ,Polymers and Plastics ,Chemical structure ,Organic Chemistry ,Chemical modification ,Polymer ,chemistry.chemical_compound ,chemistry ,Pyridine ,Polymer chemistry ,Materials Chemistry ,Side chain ,Molecule ,Organic chemistry ,Solubility ,Glass transition - Abstract
A series of acylated chitosans were synthesized by reacting chitosan with hexanoyl, decanoyl, and lauroyl chlorides. The chemical structures of these polymers were characterized by elemental analysis, IR, 1H-NMR, 13C-NMR, and GPC. These results suggested that the degree of substitution was 4 per monosaccharide ring. These acylated chitosans exhibited an excellent solubility in organic solvents such as chloroform, benzene, pyridine, and THF and transparent films were obtained from these solutions. Dynamic mechanical analyses (DMA) showed that all acylated chitosans have two phase transitions in the solid state. The first transition at −10, −42, and −40°C are attributable to the glass transition (Tg) of H-, D-, and L-chitosans, respectively. The second one around 88°C may be attributed to the transition related to the structure formed by the side chains. WAXS analyses indicate that these polymers form a layered structure in solid state and the layer spacing d increases linearly with increasing the length of side chains.
- Published
- 2000
30. Cover Picture: Macromol. Mater. Eng. 11/2015
- Author
-
Yoshiharu Kimura, Hideki Yamane, and Jungyub Hyun
- Subjects
Materials science ,Polymers and Plastics ,General Chemical Engineering ,Organic Chemistry ,Materials Chemistry ,Cover (algebra) ,Physical geography - Published
- 2015
31. Molecular mechanical analysis of polymer conformation, 2. Relation between chain conformation and birefringence of stretched non-crystalline polyurethanes with various substituent groups
- Author
-
Hideki Yamane, Masakazu Konda, Toshio Kitao, and Yoshiharu Kimura
- Subjects
chemistry.chemical_classification ,Steric effects ,Birefringence ,Polymers and Plastics ,Organic Chemistry ,Substituent ,Polymer ,Condensed Matter Physics ,chemistry.chemical_compound ,Draw ratio ,chemistry ,Chain (algebraic topology) ,Polarizability ,Polymer chemistry ,Materials Chemistry ,Phenyl group ,Physical and Theoretical Chemistry - Abstract
The relationship between birefringence and polymer structure was studied both by theoretical and experimental analyses of a series of non-crystalline polyurethanes (PU) with different side groups. The most probable steric structures of PUs were estimated by molecular mechanical calculation (MM2) of their oligomeric model compounds, and their birefringence was theoretically calculated on the structural data obtained. In addition, some of the PUs were practically synthesized and melt-spun into thin fibers, which were drawn to a maximum draw ratio to measure the values of birefringence. The comparison of the measured and estimated values revealed that the present estimation method is effective for simulating the chain conformations and the birefringence of fully or partially extended polymer chains, which ought to be formed by drawing and melt-flow of glassy materials. Of particular interest was that phenyl-substituted PUs exhibit an unexpectedly larger birefringence than methyl-substituted PUs. This fact was reasonably explained by the angular rotation of the highly polarizable phenyl group, which is energetically easily allowed and influences strongly the value of birefringence.
- Published
- 1994
32. Copolymerization of 3-(S)-[(benzyloxycarbonyl)methyl]-1,4-dioxane-2,5-dione and l-lactide: a facile synthetic method for functionalized bioabsorbable polymer
- Author
-
Yoshiharu Kimura, Toshio Kitao, Hideki Yamane, and Kenji Shirotani
- Subjects
Lactide ,Polymers and Plastics ,Organic Chemistry ,chemistry.chemical_element ,Catalysis ,chemistry.chemical_compound ,Monomer ,chemistry ,Bromide ,Hydrogenolysis ,Polymer chemistry ,Materials Chemistry ,Copolymer ,Triethylamine ,Palladium - Abstract
The copolymerization of 3-(S)-[(benzyloxycarbonyl)methyl]-1,4-dioxane-2,5-dione (BMD) and l -lactide (LAC) was carried out in bulk at relatively low BMD/LAC feed ratios with stannous 2-ethylhexanoate as the catalyst. The resulting copolymers were subjected to hydrogenolysis at atmospheric pressure in the presence of a palladium on charcoal catalyst to remove the pendant benzyl groups quantitatively. The deprotected copolymers consisted of l -lactic (L), glycolic (G) and l -α-malic acid (M) repeating units, with the copolymer composition being almost identical to the monomer feed composition.13C n.m.r. spectroscopy revealed that the BMD units (G–M) had been randomly incorporated into the copolymer (L–L). These poly(α-hydroxy acid)s with pendant car☐yl groups were found to hydrolyse more rapidly than poly( l -lactide), because of the water-absorbing and catalytic activities of the car☐yl moieties. They were allowed to react with p-azidophenacyl bromide in the presence of triethylamine to form photo affinity labelling groups at the car☐yl functionalities. These findings suggested that the malic-acid-containing poly(α-hydroxy acid)s should have a high potential for use as functionalized bioresorbable polymers.
- Published
- 1993
33. Alumina–carbon composite fibers from poly[(acyloxy)aloxane]s
- Author
-
Yoshiharu Kimura, Koichi Hashimoto, Hideki Yamane, and Toshio Kitao
- Subjects
chemistry.chemical_classification ,Materials science ,Polymers and Plastics ,Composite number ,chemistry.chemical_element ,Sintering ,General Chemistry ,Polymer ,Surfaces, Coatings and Films ,Solvent ,chemistry.chemical_compound ,chemistry ,Polymer chemistry ,Materials Chemistry ,Fiber ,Carboxylate ,Pyrolysis ,Carbon - Abstract
The alumina–carbon composite fibers were obtained from poly[(acyloxy)aloxane] (PAA) with 3-ethoxypropanoic (EPA) and m-anisic acids (m-AA) legands. This preceramic polymer can be dissolved in p-xylene-methanol-EPA mixed solvent, and the concentrated solution exhibited an excellent spinnability. During the pyrolysis and sintering processes, aliphatic carboxylate in the side groups was easily decomposed and eliminated. The aromatic carboxylate, however, seems to be converted and migrated to a carbon domain in the alumina matrix into which aloxane repetition was converted. The fibers pyrolyzed up to 800 and 1000°C have electrical conductivities that monotonically increase with increasing temperature. The fiber pyrolyzed up to 1200°C showed the electrical conductivity in a rather complicated manner.
- Published
- 1992
34. Degradation of azo-containing polyurethane by the action of intestinal flora: its mechanism and application as a drug delivery system
- Author
-
Y. Makita, Toshio Kitao, Hideki Yamane, T. Kumagai, S.I. Kim, Yoshiharu Kimura, and Haruhide Sasatani
- Subjects
chemistry.chemical_classification ,Materials science ,Polymers and Plastics ,Organic Chemistry ,Polymer ,Biodegradation ,Polyvinyl alcohol ,Dosage form ,chemistry.chemical_compound ,chemistry ,Polymer chemistry ,PEG ratio ,Drug delivery ,Materials Chemistry ,Ethylene glycol ,Polyurethane - Abstract
Several segmented polyurethanes comprising azo aromatic and hydrophilic groups were synthesized by reaction of m -xylylene diisocyanate with a mixture of m , m ′-dihydroxyazobenzene, poly(ethylene glycol) (PEG, M a = 2000) and 1,2-propanediol (propylene glycol, PG). Their polymer films were made by solution casting, and pellets of a hydrophilic drug (FOY-305) were coated with these polymers. Both the films and the coated pellets were incubated anaerobically in a culture of human intestinal flora. It was found that the azo groups in the polymer were reduced to hydrazo groups during incubation, which induced degradation of the films and the coatings without decreasing the molecular weight of the polymer. The rate of drug release from the pellets depended on both the azo and PEG compositions. Based on these findings, a new degradation mechanism of the polyurethane films and coatings is proposed.
- Published
- 1992
35. Macromol. Mater. Eng. 10/2009
- Author
-
Yoshiharu Kimura, Amalina M. Afifi, Shigeyuki Nakano, Hideki Yamane, and Hajime Nakajima
- Subjects
Materials science ,Polymers and Plastics ,Polymer science ,General Chemical Engineering ,Organic Chemistry ,Materials Chemistry - Published
- 2009
36. Alumina fibers from poly[((3-ethoxypropanoyl)oxy)aloxane]
- Author
-
Hideki Yamane, Yoshiharu Kimura, Hisao Morita, and Toshio Kitao
- Subjects
Materials science ,Polymers and Plastics ,Scanning electron microscope ,Sintering ,General Chemistry ,Surfaces, Coatings and Films ,Thermogravimetry ,Phase (matter) ,Differential thermal analysis ,Materials Chemistry ,Extrusion ,Fiber ,Composite material ,Spinning - Abstract
Alumina fibers were obtained from the poly[((3-ethoxypropanoyl)oxy)aloxane] (P-3EPA) by using a polymeric precursor technology. The rheological properties of the concentrated solution of P-3EPA related to the extrusion and spinning processes have been investigated to determine the processability into fine filaments. Thirty weight percent P-3EPA dissolved into toluene showed an excellent spinnability and fine filaments of 20–30 μm in diameter were easily obtained. The phase changes during the sintering of the fiber were studied with wide-angle X-ray diffraction and were shown to be strongly related to the mechanical properties of the fiber. Further the addition of the ethyl silicate (ES) as a sintering agent which prevent the crystal growth of Al2O3 was found to be effective to improve the mechanical properties of the alumina fiber.
- Published
- 1990
37. Coordination structure of the aluminium atoms of poly(methylaloxane), poly(isopropoxylaloxane) and poly[(acyloxy)aloxane]
- Author
-
S. Tanimoto, Yoshiharu Kimura, Hideki Yamane, and Toshio Kitao
- Subjects
chemistry.chemical_classification ,Chemistry ,chemistry.chemical_element ,Nuclear magnetic resonance spectroscopy ,Polymer ,Inorganic Chemistry ,NMR spectra database ,chemistry.chemical_compound ,Polymerization ,Aluminium ,Polymer chemistry ,Materials Chemistry ,Proton NMR ,Organic chemistry ,Atomic ratio ,Carboxylate ,Physical and Theoretical Chemistry - Abstract
Poly(methylaloxane) ( 1 ), prepared by hydrolytic polymerization of trimethyl-aluminium (TMA), was reacted with isopropanol (IP) to obtain poly(isopropoxylaloxane) ( 2 ). This was further reacted with propionic acid (PA) to prepare poly[(propionyloxy) aloxanel ( 3 ), with various ratios of PA ligands. By gasmetry of the methane produced in the reaction, as well as by the 1 H NMR spectroscopy of the products, both 1 and 2 were found to contain less reactive terminal A1Me and AlOH groups. For 3 , the unit structure and molecular weight were controlled by the PA/TMA ratio reacted. The 27 A1 NMR spectra of these products revealed that the coordination states of the aluminium atoms are different, depending on the O/A1 atomic ratio in the products. In the case of 1 , which has a low O/A1 ratio, the aluminium atoms are penta-coordinated, while in 2 and 3 hexa-coordination is involved. Based on these data the structures of poly(aloxanes) ( 1 – 3 ) are discussed.
- Published
- 1990
38. [Untitled]
- Author
-
Yoshiki Chujo, Kensuke Naka, Yong Zhou, Qingqing Ni, Hideki Yamane, Hideaki Itoh, and Wenxing Chen
- Subjects
In situ ,Bioconjugation ,Chemistry ,fungi ,Metals and Alloys ,Fibroin ,General Chemistry ,Redox ,Catalysis ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Ion ,Gold Colloid ,Colloid ,Residue (chemistry) ,Polymer chemistry ,Materials Chemistry ,Ceramics and Composites - Abstract
A novel core–shell gold colloid–silk fibroin (SF) bioconjugate was prepared by the protein in situ redox technique at room temperature, in which the tyrosine (Tyr) residue of the SF, having strong electron donating properties, in situ reduced Au(III) ions to Au colloids showing a stable and highly monodispersed nature.
- Published
- 2001
39. Cover Picture: Macromol. Rapid Commun. 23/2004
- Author
-
Yukiko Furuhashi, Hideki Yamane, Teruo Monno, Yutaka Kawahara, Yoshiharu Kimura, Atsushi Nakayama, and Tadahisa Iwata
- Subjects
Materials science ,Polymers and Plastics ,Organic Chemistry ,Materials Chemistry ,Cover (algebra) ,Remote sensing - Published
- 2004
40. Novel melt-processable poly[(acyloxy)aloxane] as alumina precursor
- Author
-
Masaya Furukawa, Yoshiharu Kimura, Toshio Kitao, and Hideki Yamane
- Subjects
Inorganic Chemistry ,Polymers and Plastics ,Chemistry ,Stereochemistry ,Organic Chemistry ,Polymer chemistry ,Materials Chemistry - Published
- 1989
41. Preparation of block copoly(ester-ether) comprising poly(l-lactide) and poly(oxypropylene) and degradation of its fibre in vitro and in vivo
- Author
-
Toshio Kitao, Hideki Yamane, Yoshiharu Kimura, and Yuji Matsuzaki
- Subjects
Lactide ,Materials science ,Polymers and Plastics ,Organic Chemistry ,Oligomer ,Biodegradable polymer ,Gel permeation chromatography ,chemistry.chemical_compound ,Monomer ,Polypropylene glycol ,chemistry ,Polymerization ,Polymer chemistry ,Materials Chemistry ,Copolymer ,sense organs - Abstract
The A-B-A triblock copoly(ester-ether)s comprising poly( l -lactide) (A) and poly(oxypropylene) (B) were prepared by the copolymerization of l -lactide and polypropylene glycols (PPG) with mono-dispersed molecular weights of 2000 and 4000. A Me3AlH2O catalyst system was utilized as the initiator. When the feed ratios of PPG 2000 and 4000 were over 5 and 10 wt% relative to l -lactide, respectively, the polymerization of l -lactide took place from the PPG hydroxy terminals to give the desired A-B-A block copolymers in high yields. Their molecular weights were found to be coincident with the values estimated from the monomer conversions and the feed ratios of PPG. At the lower feed ratios of PPG, the poly( l -lactic acid) (P l LA) homopolymer was formed together with the block copolymers. The copolymers were melt-spun by the conventional method and the fibres obtained were extended by drawing at 80–90°C. At the same draw ratio the modulus of the fibres was decreased with increasing PPG content in the copolymers. The fibres of the P l LA-PPG 4000 copolymers with different content of PPG were subjected to degradation both in vitro and in vivo. Upon immersion in a phosphate buffer (pH = 7.2) the fibres showed a time-dependent decrease in tensile strength with accompanying surface erosion. The rate of this degradation was much higher than that of the fibre of P l LA ( M n = 62 000 ). The same fibres, implanted under the dorsal skin of rats, caused a degradation similar to that observed in vitro without eliciting a significant rejection and inflammation. The block copolymers comprising P l LA and PPG, therefore, were shown to have high potentiality as the biodegradable polymers with improved flexibility and biodegradability.
- Published
- 1989
42. Extrusion and melt spinning characteristics of thermally degraded polypropylene
- Author
-
James L. White and Hideki Yamane
- Subjects
Polypropylene ,Materials science ,Polymers and Plastics ,General Chemistry ,Die swell ,Swell ,Viscosity ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,Degradation (geology) ,Molar mass distribution ,Extrusion ,Composite material ,Melt spinning - Abstract
A basic study of the influence of thermal degradation of polypropylene on its extrudate swell and melt spinning characteristics is reported. The degradation reduces swell, changes the shape of the spinline diameter/velocity profile (i.e., the spinline apparent elongational viscosity function), and stabilizes the melt spinning process. The importance of molecular weight distribution narrowing during the degradation process is noted in these studies.
- Published
- 1983
43. Ring-opening polymerization of 3(S)-[(benzyloxycarbonyl)methyl]-1,4-dioxane-2,5-dione: a new route to a poly(.alpha.-hydroxy acid) with pendant carboxyl groups
- Author
-
Yohiharu Kimura, Kenji Shirotani, Toshio Kitao, and Hideki Yamane
- Subjects
Inorganic Chemistry ,chemistry.chemical_classification ,chemistry.chemical_compound ,Alpha hydroxy acid ,Polymers and Plastics ,chemistry ,Organic Chemistry ,Materials Chemistry ,Organic chemistry ,1,4-Dioxane ,Medicinal chemistry ,Ring-opening polymerization - Abstract
Obtention d'un copolymere alterne forme d'unites acide glycolique et α-(S)-malate de benzyle
- Published
- 1988
44. Novel thermo-responsive formation of a hydrogel by stereo-complexation between PLLA-PEG-PLLA and PDLA-PEG-PDLA block copolymers
- Author
-
Tomoko Fujiwara, Shinichi Sakurai, Yoshiharu Kimura, Takashi Mukose, Hideki Yamane, and Tetsuji Yamaoka
- Subjects
Aqueous solution ,Materials science ,Polymers and Plastics ,Bioengineering ,Biomaterials ,Rheology ,Intermolecular interaction ,PEG ratio ,Polymer chemistry ,Materials Chemistry ,Copolymer ,Enantiomer ,Thermo responsive ,Biotechnology - Abstract
Gel formation was discovered in an aqueous mixture of enantiomeric triblock copolymers, PLLA-PEG-PLLA and PDLA-PEG-PDLA. This system is characteristic in that an interesting sol–gel transition was induced by the stereo-complexation of the PLLA and PDLA segments of the block copolymers around 37°C. The process of gel formation was clearly monitored by the rheological change, and the responsibility of the stereo-complex formation for the gelation was confirmed by wide-angle X-ray scattering. The mechanism of this gel formation is discussed in relation to its potential applications.
Catalog
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