研究者詳細 - 山崎　慎一

論文 - 山崎　慎一

分割表示 111 件中 81 - 100 件目／全件表示 >>

Copolymerization effect on morphology of polymer crystals prepared from 4-acetoxybenzoic acid and 4-(4-acetoxyphenyl)benzoic acid

Naomi Yoshida, Yasuhiro Kurihara, Shinichi Yamazaki, Kunio Kimura

Polymer Preprints, Japan 55 ( 1 ) 547 2006年

記述言語：日本語掲載種別：研究論文（国際会議プロシーディングス）

We had been studying a dual self-assembling polycondensation system by means of phase separation of oligomers, which is a novel polycondensation system to prepare separately the two kinds of polymer crystals having different structures. This phenomenon was induced by the difference in the oligomer interaction such as hydrogen bonding. In this study, a dual self-assembling polycondensation was found in the solution polymerization of 4-acetoxybenzoic acid (ABA) and 4-(4-acetoxyphenyl)benzoic acid (APBA). Two different kinds of crystals were simultaneously formed, of which one was needle-like crystal and another was fibrillated slab-like crystals. These morphologies resembled those of corresponding homopolymer crystals. Microscopic FT-IR analysis suggested that these two crystals had different structure. The miscibility of the oligomers prepared from APBA was quite lower than those from ABA, and this large difference in the miscibility may induce the simultaneous formation of two kinds of crystals having different crystal habit.

Preparation of aromatic polyesters by using fractional polycondensation under shearing condition

Chie Iwado, Shin-Ichiro Kohama, Shinichi Yamazaki, Kunio Kimura

Polymer Preprints, Japan 55 ( 1 ) 545 2006年

記述言語：日本語掲載種別：研究論文（国際会議プロシーディングス）

We have found that poly(p-oxybenzoyl) (POB) was selectively prepared by the fractional polycondensation of p-acetoxybenzoic(p-ABA) acid and m-acetoxybenzoic acid in poor solvents by using the phase separation of oligomers, and shearing was of importance for the fractionability. In this study, fractional polycondensation of POB was examined in the copolymerization of p-ABA and 3-(4-acetoxyphenyl)propionic acid (p-APPA) to clarify the shearing effect on the fractionability. This copolymerization had also fractionability and the precipitates rich in p-oxybenzoyl moiety were selectively obtained. The shearing enhanced the fractionability and the content of p-oxybenzoyl moiety of the precipitates prepared at the content of ABA in feed of 70mol% was 92.6%, which was almost POB. The shearing increased the solubility of cooligomers and therefore, this provided the suitable circumstance that homo-oligomers were selectively phase-separated.

Topological Mechanism of Polymer Nucleation and Growth – The Role of Chain Sliding Diffusion and Entanglement 招待査読

Advances in Polymer Sciences 191 137 - 186 2005年10月

Formation mechanism of shish in the oriented melt (II) - two different growth mechanisms along and perpendicular to the flow direction 査読

S Yamazaki, K Watanabe, K Okada, K Yamada, K Tagashira, A Toda, M Hikosaka

POLYMER 46 ( 5 ) 1685 - 1692 2005年2月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCI LTD

In part I of this series of paper, we have solved the formation mechanism of shish from the oriented melt based on the kinetic observation. In this work, we have shown for the first time the molecular mechanism of the growth of shish by kinetic study. We found that there are two different type of the growth of shish against the flow direction. The growth rate along the flow direction (U) is proportional to DeltaT, where DeltaT is the degree of supercooling. This indicates that U is mainly controlled by the rearrangement process of the chain near the end surface of the shish. On the other hand, the growth rate perpendicular to the flow direction (V) obeyed a well-known equation Vproportional to exp(-B/DeltaT), where B is a constant proportional to the free energy necessary for forming a critical secondary nucleus DeltaG*. This indicates that V is mainly controlled by the secondary nucleation process on the side surface of shish. Moreover, we also found that there is a critical shear rate gamma (over dot)* for the growth of shish. Below gamma (over dot)*, U and V approached to zero and the growth rate of spherulite, respectively. From this experimental fact, we proposed that the chain conformation near the interface between the melt and shish, i.e. near the end and side surface of shish is elongated and oriented by the shear flow above gamma (over dot)*. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2004.12.010

Electrical conductivity and electromagnetic interference shielding effectiveness of polyaniline-ethylene vinyl acetate composites 査読

NC Das, S Yamazaki, M Hikosaka, TK Chaki, D Khastgir, A Chakraborty

POLYMER INTERNATIONAL 54 ( 2 ) 256 - 259 2005年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JOHN WILEY & SONS LTD

Electrical conductivity and electromagnetic interference (EMI) shielding effectiveness at microwave (200-2000 MHz) and X-band (8-12 GHz) frequency range of polyaniline (PAni) composites were studied. It has been observed that EMI shielding of conductive polyaniline (PAni)-ethylene vinyl acetate composites increases with the increase in the loading levels of the conductive polymer doped with dodecylbenzene sulfonic acid. The result indicates that the composites having higher PAni loading (> 23%) can be used for EMI shielding materials and those with lower PAni loading can be used for the dissipation of electrostatic charge. (C) 2004 Society of Chemical Industry.

DOI： 10.1002/pi.1660

Formation mechanism of shish in the oriented melt (I) - bundle nucleus becomes to shish 査読

S Yamazaki, K Watanabe, K Okada, K Yamada, K Tagashira, A Toda, M Hikosaka

POLYMER 46 ( 5 ) 1675 - 1684 2005年2月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCI LTD

We have solved the molecular mechanism of the formation of shish of isotactic-polypropylene (iPP) and polyethylene (PE) from the sheared melt based on kinetic study by means of polarizing optical microscope. We found that the rate determining process for the formation of shish is a nucleation process in the most range of degree of supercooling (DeltaT) except for large DeltaT of PE. We have shown a direct evidence of the formation of bundle nucleus from the oriented melt, which is consisted of elongated chains caused by artificial pins. For polymers, a universal mechanism of nucleation from the isotropic or oriented melt was proposed. We also found that there is a critical shear rate for the formation of shish. This experimental fact indicates that the shish will be formed when the elongation of chains will overcome the conformational relaxation of chains and chain conformation within the oriented melt is kept liquid crystal like one. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2004.12.009

Fabrication of poly(p-oxybenzoyl) nanowhisker 査読

K Kimura, S Yamazaki, Y Matsuoka, Y Yamashita

POLYMER JOURNAL 37 ( 12 ) 906 - 912 2005年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：NATURE PUBLISHING GROUP

Fabrication of poly(p-oxybenzoyl) (POB) nanowhiskers was examined by using reaction-induced crystallization of oligomers during the polymerization of p-acetoxybenzoic acid in liquid paraffin. Width of the POB whiskers was susceptible to polymerization temperature and it was efficiently controlled by a change in temperature during the polymerization. Increase in polymerization temperature just after nucleation (Han) reduced the degree of super saturation of oligomers (or) resulting in the depression of the width increase by the crystallization of oligomers on side surface of the whiskers. Temperature drop just before nucleation (Cbn) enhanced the value of a resulting in the generation of much more nuclei having the smaller width. On the basis of these results, the combination of these two methods Han and Cbn afforded the whiskers having the smallest width, and the POB nanowhiskers were prepared of which the width and the length were 190nm and 18.6 mu m, respectively.

DOI： 10.1295/polymj.37.906

Morphology control of poly(p-oxycinnamoyl) by direct polycondensation with aromatic anhydride

Toshimitsu Nakanishi, Shin-Ichiro Kohama, Shinichi Yamazaki, Kunio Kimura

Polymer Preprints, Japan 54 ( 1 ) 1824 2005年

記述言語：日本語掲載種別：研究論文（国際会議プロシーディングス）

Direct polycondensation of p-hydroxycinnamic acid was carried out in the presence of an aromatic anhydride such as benzoic anhydride and p-ethoxybenzoic anhydride by means of reaction-induced phase separation of oligomers. Poly(p-oxycinnamoyl) (POC) spheres were prepared in liquid paraffin in the presence of both aromatic anhydrides at 280 - 320°C. On the other hand, POC crystals having clear habits were prepared in hydrogenated terphenyl mixture in the presence of p-ethoxybenzoic anhydride at 260°C. Especially, POC needle-like crystals were prepared in good yield at 260°C at a concentration of 10.0 %. WAXS patterns of POC plate-like and needle-like crystals showed that these crystals possessed quite high crystallinity compared with POC spheres. It was concluded that the morphology of POC was tunable by not only the solvent but also the aromatic anhydride as condensation reagent.

Formation of shish under flow with low shear rate - Effect of addition of irregular shaped particles

Shinichi Yamazaki, Kanji Wakabayashi, Kenta Mizuma, Kunio Kimura

Polymer Preprints, Japan 54 ( 2 ) 3157 - 3158 2005年

記述言語：日本語掲載種別：研究論文（国際会議プロシーディングス）

Previously, we have shown that the shish was formed from the oriented melt composed of the elongated chains caused by dust particles within the melt via bundle typed nucleation under flow with low shear rate ( γ̇
=5s -1). This implies that dust particles effectively cause the elongation of chains within the melt. In this work, we observed the crystallization of iPP added with irregular shaped particles under shear flow by means of polarizing optical microscope. We prepared various shaped particles such as confetti-like, spherical and rock-like. We found that the size and asymmetric shape of additional particles are important for effective formation of shish.

Influence of shearing on fractutional polycondensation of aromatic polyester

Chie Iwado, Toshimitsu Ichmori, Shinichi Yamazaki, Kunio Kimura

Polymer Preprints, Japan 54 ( 2 ) 2679 2005年

記述言語：日本語掲載種別：研究論文（国際会議プロシーディングス）

Selective preparation of poly(p-oxybenzoyl) (POB) in copolymerization system of p-acetoxybenzoic acid (p-ABA) and m-acetoxybenzoic acid (m-ABA) was examined by using reaction-induced crystallization under shearing condition. POB crystals were mainly precipitated in liquid paraffin solution even at the content of m-ABA in feed (χf) of 30 mol% without stirring. In contrast to this, they were formed even at χf of 50 mol% and the fractionability was significantly enhanced by shearing. The mechanism of the fractional polycondensation was attributed to both the reactivity of monomer and the phase separation behavior of oligomer. Under shearing condition, the difference on the reactivity between p-ABA and m-ABA was lowered. However, the shearing induced the crystallization of homo-oligomers of p-oxybenzoyl unit more efficiently and prevented the precipitation of co-oligomers via crystallization. Thereby homo-oligomers were more rapidly and selectively precipitated by crystallization to form the POB crystals.

Solid-state polycondensation of aromatic polyimide by means of crystallization of oligomers during solution polymerization

Kanji Wakabayashi, Shinichi Yamazaki, Kunio Kimura

Polymer Preprints, Japan 54 ( 2 ) 2555 2005年

記述言語：日本語掲載種別：研究論文（国際会議プロシーディングス）

Poly(4,4'-oxydiphenylene pyromelliteimide)(PI(PMDA/DPE)) were prepared from PMDA and DPE as monomers at condition of 0.50% and 280°C in TS10 (mixture of isomers of dibenzyltoluene). Lath-like crystals and particles composed with plate-like crystals were obtained via the crystallization of oligomers during solution polymerization. The products exhibited high crystallinity and high inherent viscosity of 1.17 dig-1. This implies solid-state polymerization effectively progressed in the crystals of oligomer, because the chain ends in the oligomers crystal were advantageously arranged for polycondensation reaction.

Fabrication of poly(p-oxycinnamoyl) needle crystals by using hydrodynamically induced crystallization during solution polymerization

Mayuko Muraoka, Shinichi Yamazaki, Kunio Kimura

Polymer Preprints, Japan 54 ( 1 ) 600 2005年

記述言語：日本語掲載種別：研究論文（国際会議プロシーディングス）

Morphology control of poly(p-oxycinnamoyl) (POC) was studied to overcome the poor processability and microspheres were prepared by the self-organizing polycondensation of (E)-4-acetoxycinnamic acid (ACA) in aromatic solvent at 320°C without stirring. The work reported investigated the fabrication of POC needle crystals by hydrodynamically induced crystallization during polymerization of ACA. Polymerizations of ACA were carried out in a cylindrical vessel equipped with a stirring bar at a concentration of 1.5% under stirring with different speed (γ) of 300, 700 and 1100 rpm. Microspheres were obtained at γ of 300 rpm via liquid-liquid phase separation. In contrast to this, morphology was drastically changed from sphere to needle at γ of 700 and 1100 rpm These needle crystals were obtained with the yield of 22-27 %, which were 1.0-1.5 μm in length and 1.0-1.5 μm in width. The purely laminar flow in the cylindrical vessel at low stirring speed changed to Taylor vortices with the increase of γ and this brought about the huge concentration of oligomers along to the circular flow leading to the crystallization to form the needle crystals.

Direct synthesis of polyamides by using crystallization during polymerization

Kentaro Kobayashi, Shinichi Yamazaki, Kunio Kimura

Polymer Preprints, Japan 54 ( 1 ) 304 2005年

記述言語：日本語掲載種別：研究論文（国際会議プロシーディングス）

Direct polycondensations of isophthalic acid (IPA) and p-phenylenediamine (PPDA) were carried out by means of reaction-induced crystallization of oligomers. Poly(p-phenylene isophthalamide) (PPIA) plate-like crystals were obtained in good yield. The crystals exhibiting clear habits possessed high crystallinity. PPDA / IPA = 1.4 - 1.5 gave the highest intrinsic viscosity ([η]) of 0.37 dl/g. The yield and [η] of the polymers and the dissolved oligomers were measured in the course of the polymerization in order to examine polycondenastion feature. [η] of the polymers was increased even after the polymer yield was leveled off. On the other hand, [η] of the dissolved oligomers was constant through the polymerization. From these results, it was concluded that the polycondensation of IPA and PPDA proceeded as follows. When the molecular weight of oligomers exceeded the critical value, they were crystallized to form crystals. Solid-state polycondensation subsequently occurred in the crystals. Finally, PPIA were obtained as a form of crystals.

Synthesis of novel fluorine-containing poly(oxadiazole-ether)s

Natsuko Sato, Shunsuke Masaki, Shinichi Yamazaki, Kunio Kimura

Polymer Preprints, Japan 54 ( 1 ) 287 2005年

記述言語：日本語掲載種別：研究論文（国際会議プロシーディングス）

We had been studying the synthesis of fluorine-containing polymers derived from 2,3,4,5,6-pentafluorobenzoic acid. This paper described the synthesis and characterization of novel fluorine-containing poly(arylether 1,3,4-oxadiazole)s(F-PEOs). Monomer was synthesized from hydrazine hydrate and 2,3,4,5,6-pentafluorobenzoyl chloride. F-PEOs were synthesized by nucleophilic aromatic substitution reaction at 30°C in NMP. The polymers obtained by stopping just before the gelation were all para connected linear structures confirmed by NMR. The obtained F-PEOs showed excellent solubility and afforded tough transparent films by solution casting method. They also exhibited high Tg of 157-257°C and good thermal stability, and excellent hydrophobicity due to the incorporation of 2,3,5,6-tetrafluoro-1,4-phenylene moiety.

Morphology control of poly(azomethine ester) by using reaction-induced oligomer phase separation

Yasuhide Yakushi, Shinichi Yamazaki, Tetsuya Uchida, Kunio Kimura

Polymer Preprints, Japan 54 ( 2 ) 4777 - 4778 2005年

記述言語：日本語掲載種別：研究論文（国際会議プロシーディングス）

Spindle-like crystals of poly(azomethine ester) (PAME) were formed by the polymerization of 4-(4-acetoxybenzylidenamino)benzoic acid (ABBA) in liquid paraffin (LPF) at 300°C via reaction-induced crystallization of oligomers. But the trace of lamellae stacking structure was observed on the surface of crystals due to the lack of post-polymerization between the oligomers in the crystals. In order to induce the crystallization at 350°C to accelerate the post-polymerization, the polymerization of ABBA was carried out in the mixed solvent of LPF and aromatic solvent. This polymerization afforded the fibrillar crystals having smooth surface. One-pot polymerization of 4-acetoxybenzaldehyde and 4-aminobenzoic acid yielded ribbon-like PAME crystals besides spherical precipitates. These ribbon-like crystals showing the larger width than the fibrillar crystals prepared from ABBA were formed by the crystallization of oligomers through the stepwise formation of azomethine linkage and ester linkage during the elevated temperature polymerization. These crystals possessed quite high crystallinity as well as the fibrillar crystals. The morphology of PAME was controllable by means of precipitation during solution polymerization.

Morphology control of aromatic polyimide by using reaction-induced phase separation of oligomers

Kanji Wakabayashi, Shinichi Yamazaki, Kunio Kimura

Polymer Preprints, Japan 54 ( 1 ) 599 2005年

記述言語：日本語掲載種別：研究論文（国際会議プロシーディングス）

We had reported that lozenge-shaped crystals and microspheres of poly(p-phenylene pyromelliteimide) were prepared by means of reaction-induced phase separation of oligomers during solution polymerization. These morphologies could be controlled on the basis of the miscibility between solvent and oligomers. In this paper, we investigated on the morphology control of Kapton by using the phase separation of oligomer during polymerization. Microspheres of Kapton were obtained in an aromatic solvent at a concentration of 3.0 wt/vol%. In contrast to this, lath-like crystals and spheres composed of plate-like crystals were obtained at a concentration of 0.5 wt/vol%. These products exhibited high crystallinity and possessed high heat-resistance. Influences of solvent and polymerization temperature on the morphology were also presented.

Mechanism of acceleration of growth rate under shear flow -universal role of the "oriented melt" near the surface

Kaori Watanabe, Masamichi Hikosaka, Kiyoka Okada, Akihiko Toda, Motoi Yamashita, Shinichi Yamazaki, Takashi Taniguchi, Kiyohito Koyama, Koji Yamada, Kastuhaeu Tagashira

Polymer Preprints, Japan 54 ( 1 ) 626 2005年

記述言語：日本語掲載種別：研究論文（国際会議プロシーディングス）

We propose that shear rate γ̇ (Z) within the interface significantly increases and conformation of molecular chains will be elongated. When γ̇ (Z) becomes larger, the elongation of chains will overcome the entropic relaxation, that results in formation of the "oriented melt". Universal crystallization mechanism under shear flow is proposed that the growth rate of spherulite or shish is accelerated near the surface, that is due to formation of the oriented melt.

Equilibrium melting temperature of isotactic polypropylene with high tacticity: 1. Determination by differential scanning calorimetry 査読

K Yamada, M Hikosaka, A Toda, S Yamazaki, K Tagashira

MACROMOLECULES 36 ( 13 ) 4790 - 4801 2003年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

A new method to determine the correct Gibbs-Thomson plot and equilibrium melting temperature (T-m(0)) of polymers was proposed. The Gibbs-Thomson plot method is reliable, because the Gibbs-Thomson equation is directly derived from thermodynamical relations. In this method, the heating rate dependence of melting temperature (T.) was omitted by applying the theory of the "melting kinetics", and the effect of lamellar thickening on T. was also omitted by observing thick lamellae. A differential scanning calorimeter (DSC) was used for observation of T. as a conventional method. Transmission electron microscope (TEM) was used to observe a distribution of lamellar thickness (l). It was shown theoretically that peak temperature of melting endotherm (T.(DSC)) corresponded to averaged reciprocal l (<l(-1)>) for the case of sharp distributions of T-m and l(-1). The Gibbs-Thomson plot, T-m (DSC) vs <l(-1)>, was carried out. A reliable Gibbs-Thomson plot and T-m(0) = 186.2 degreesC were obtained for a fraction of isotactic polypropylene (iPP) with high tacticity ([mmmm] = 99.6%, M-n = 64 x 10(3) and MwMn = 2.4). It was shown that DSC double melting endotherm corresponded to the number-distribution of l(-1), when lamellar thickening did not occur.

DOI： 10.1021/ma021206i

Equilibrium melting temperature of isotactic polypropylene with high tacticity. 2. Determination by optical microscopy 査読

K Yamada, M Hikosaka, A Toda, S Yamazaki, K Tagashira

MACROMOLECULES 36 ( 13 ) 4802 - 4812 2003年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

In part 1 of this series, we proposed a new method to determine the correct equilibrium melting temperature (T-m(0)). Effects of the "melting kinetics" and lamellar thickening were omitted from T-m. The correct T-m(0) of isotactic polypropylene (iPP) ([mmmm] = 99.6%, M-n = 64 x 10(3), and M-w/M-n = 2.4) was observed to be 186.1 degreesC. In this paper, the rigorous Gibbs-Thomson plot was obtained by using the direct correspondence between maximum melting temperature (T-m,T-max) and maximum lamellar thickness (l(max))- T-m,T-max and l(max) were observed by means of optical microscope and transmission electron microscope (TEM), respectively. The validity of the Gibbs-Thomson plot obtained by means of a differential scanning calorimeter (DSC) (part 1 of this series) was confirmed by comparing it with the rigorous Gibbs-Thomson plot in this paper. The Hoffman-Weeks plot is widely used as one of the methods to obtain T-m(0). It was shown that the Hoffman-Weeks plot is correct only when l proportional to 1/DeltaT where DeltaT is the degree of supercooling, is satisfied. However, in the case of iPP, the condition is not satisfied, and so the result obtained by the Gibbs-Thomson plot is not equivalent to that obtained by the Hoffman-Weeks plot. The existence of alpha2' phase was confirmed again by breakings in slopes of l and T-m against T-c at 159 degreesC. Furthermore, the broad bimodal distribution of l was caused by the difference between the lamellar thickening growth rate of isolated mother lamellae and the lamellae thickening rate of stacked daughter lamellae.

DOI： 10.1021/ma021207a

Direct evidence of nucleation during the induction period of polyethylene crystallization by SAXS 査読

M Hikosaka, S Yamazaki, Wataoka, I, NC Das, K Okada, A Toda, K Inoue

JOURNAL OF MACROMOLECULAR SCIENCE-PHYSICS B42 ( 3-4 ) 847 - 865 2003年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：MARCEL DEKKER INC

Direct evidence that nuclei are formed during the induction period of crystallization is obtained for the first time by means of small-angle X-ray scattering (SAXS). Polyethylene (PE) was used as a model crystalline polymer. The nucleating agent was mixed with PE in order to increase the scattering intensity I-x from nuclei as large as 10(4) times bigger than usual. I-x increased soon after quenching to the crystallization temperature from the melt and saturated after some time. A new theory is proposed to estimate the size of the nuclei N, the number density distribution of nuclei with N at time t, f(t,N), and the induction time tau(i), by analyzing the SAXS scattering intensity. The volume-averaged size of the nuclei nearly the same as that of critical nuclei and does not change so much with time during the induction period. Lamellae start stacking much later than nuclei start forming.

DOI： 10.1081/MB-120021610

　前のページ - 次のページ　

1
2
3
4
5
6