研究者詳細 - 山崎　慎一

論文 - 山崎　慎一

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Molecular weight dependence of equilibrium melting temperature and lamellar thickening of isotactic polypropylene with high tacticity 査読

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

JOURNAL OF MACROMOLECULAR SCIENCE-PHYSICS B42 ( 3-4 ) 733 - 752 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

Molecular weight (M) dependence of the equilibrium melting temperature (T-m(o)) of isotactic polypropylene (iPP) with high tacticity ([mmmm] = 99.6%) was studied. Four fractionated iPPs with M-n = 23 x 10(3), 64 x 10(3), 94 x 10(3), and 263 x 10(3) were used. T-m(o) was obtained by using an improved method based on the Gibbs-Thomson plot proposed in previous papers. The effect of "melting kinetics" on melting temperature (T-m) was eliminated by observing isothermal melting of spherulites. The effect of lamellar thickening on Tm during T, measurement at high temperature was also eliminated by observing thick lamellae formed at high crystallization temperatures (T-c = 148 similar to 166 degreesC). With increase of M, T-m(o) increased significantly. The empirical equation, T-m(o) = 119.5 + 23.6 x log M - 2.0 x (log M)(2) (degreesC), was obtained. The molecular weight dependence of the alpha2-alpha2' transition was observed. The transition temperature (Talpha2-alpha2') also increased with increase of M. The DeltaT dependence of lamellar thickness was concluded to be controlled by that of lamellar thickening.

DOI： 10.1081/MB-120021603

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Nucleation and morphology of polyethylene under shear flow 査読

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

JOURNAL OF MACROMOLECULAR SCIENCE-PHYSICS B42 ( 3-4 ) 499 - 514 2003年

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：MARCEL DEKKER INC

Effect of the shear flow ((gamma)over dot = 0.5 similar to 5 s(-1)) on the nucleation and on the morphology of polyethylene (PE) during crystallization from the melt was studied by means of polarizing optical microscopy and small angle X-ray scattering. In order to analyze the results by the nucleation theory, we observed the effect of shear flow on the equilibrium melting temperature (T-m(0)). The T-m(0) under shear flow and that under quiescent state are almost the same, T-m(0) = 140.2 similar to 140.3degreesC. Therefore, the shear flow does not affect the T-m(0). The "heterogeneous" primary nucleation rate (1) and the induction onset time of nucleation (tau(onset)) of the isolated crystals under shear flow are also almost the same as those under quiescent state. The heterogeneous primary nucleation means that isolated nuclei are sporadically generating from the melt with the aid of heterogeneities such as nucleating agents. After the generation of primary nuclei, the "shish" were generated independent of the primary nucleation. We found that the shish were formed by the chain elongation caused by the velocity difference between polymer chains and dust particles, etc. After that, we observed that the "kebabs" were formed on the shish. It was found that the nucleation from the melt after melting of the "shish-kebabs" (at melt annealing temperature T-max = 160degreesC for 5 min) was accelerated compared with the ordinary melt crystallization after melting of folded chain crystals. This indicates that the "solid memory effect" of the former solid is significant. This is because of the low entanglement density within the melt of shish kebabs.

DOI： 10.1081/MB-120021578

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Role of Entanglement in Nucleation and ‘Melt Relaxation’ of Polyethylene 査読

Shinichi Yamazaki, Masamichi Hikosaka, Akihiko Toda, Isao Wataoka, Fangming Gu

Polymer 43 ( 24 ) 6585 - 6593 2002年11月

Power law of molecular weight of the nucleation rate of folded chain crystals of polyethylene 査読

SK Ghosh, M Hikosaka, A Toda, S Yamazaki, K Yamada

MACROMOLECULES 35 ( 18 ) 6985 - 6991 2002年8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

molecular weight (M.) dependence of the primary nucleation rate (I) of folded chain single crystals (FCSCs) of polyethylene (PE) was studied. A power law for the nucleation rate, I proportional to M-n (-2.4), was found. The FCSCs were formed by isothermal crystallization from the melt into an ordered phase (=orthorhombic phase). A new experimental method was established to obtain reliable I, which has been difficult in the case of heterogeneous nucleation for long years. The degree of supercooling (DeltaT) dependence of I fits well with the theoretical I given by classical nucleation theory, I = I-0 exp(-DeltaG*/kT) proportional to D exp(-C/DeltaT(2)), where I-0 is proportional to the topological diffusion coefficient of polymer chains (D), DeltaG* is the free energy for forming a critical nucleus, k is the Boltzmann constant, T is temperature, and C is a constant. It is found that DeltaG* (-C) does not depend on M., while I0 decreases with increase of M., from which it is concluded that formation of a critical nucleus is not controlled by M., while only topological diffusion of polymers is controlled by M-n, i.e., I proportional to D(M-n). Similar power laws of PE were already found by the present authors on I of extended chain single crystals (ECSCs), i.e., I proportional to M-n(-10), and on the lateral growth rates (V) of ECSCs and FCSCs, V proportional to M-n(-0.7) and V proportional to M-n(-1.0), respectively. ECSCs were formed by isothermal crystallization from the melt into a disordered phase (=hexagonal phase). Therefore, it is concluded that a common power law, I, V proportional to D(M-n) proportional to Mn-H of PE is confirmed, irrespective of nucleation or growth and irrespective of crystalline phases, ordered or disordered phases. It is to be noted that the power H depends on the degree of order of the crystalline phase, from which it is concluded that both nucleation and growth are controlled by the "topological" diffusion of polymer chains within interface between a nucleus (or crystal) and the melt and/or within the nucleus. The "topological" diffusion is related to chain sliding diffusion and disentanglements.

DOI： 10.1021/ma0105901

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Second-order phase transition of high isotactic polypropylene at high temperature 査読

FM Gu, M Hikosaka, A Toda, SK Ghosh, S Yamazaki, M Arakaki, K Yamada

POLYMER 43 ( 4 ) 1473 - 1481 2002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：ELSEVIER SCI LTD

A second-order phase transition of alpha2 form isotactic polypropylene (iPP) is found at high annealing temperature (T-a = 159.3 degreesC) by means of X-ray diffraction method. Although the lattice shape and the space group keep the same as those of the alpha2 form, i.e. monoclinic and P2(1)/c, with increase of T-a, it has been revealed that there are discontinuous increases in the slopes of the lattice constants a and b against T-a plots, while the c and the beta keep almost constant. As a result, the slope of the unit cell volume V versus T-a plot also shows a discontinuous increase at T-a = 159.3 degreesC, indicatin- the occurrence of the second-order phase transition. In order to distinguish the two phases, the phase above the transition temperature is named alpha2' phase and the transition temperature is denoted Talpha2-alpha2'. These facts suggested that the alpha2' form is a mobile phase where the molecular chains would become loosely packed and mobile, promoting the better chain sliding diffusion. A fast lamellar thickening process has been confirmed in the higher temperature region than Talpha2-alpha2', which was reported in the precedent paper. General significance is proposed that mobile phases possibly exist at high temperature, close to the melting temperature and accelerate lamellar thickening, which improves physical properties of polymers. (C) 2001 Published by Elsevier Science Ltd.

DOI： 10.1016/S0032-3861(01)00667-X

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Effect of entanglement on nucleation rate of polyethylene 査読

S Yamazaki, M Hikosaka, FM Gu, SK Ghosh, M Arakaki, A Toda

POLYMER JOURNAL 33 ( 11 ) 906 - 908 2001年

C-13 NMR relaxation of poly(acrylic acid) in aqueous solution. Effects of charge density on local chain dynamics 査読

S Yamazaki, Noda, I, A Tsutsumi

POLYMER JOURNAL 32 ( 1 ) 87 - 89 2000年

Persistence lengths of ionenes in methanol 査読

S Yamazaki, Y Muroga, Noda, I

LANGMUIR 15 ( 12 ) 4147 - 4149 1999年6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：AMER CHEMICAL SOC

To characterize the local conformations of ionenes, persistence lengths (P-1) were measured for 4,4-, and 6,6-ionenes (m,m-ionene) and 1,1-oxyethyleneionene (1,1-OEI) in methanol by small-angle X-ray scattering. It was found that P-1's of all the ionenes are almost identical (1.4 +/- 0.2 nm).

DOI： 10.1021/la981120b

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Chain Conformation of Aliphatic α,ω-Diamines in Aqueous Solutions 査読

Shinichi Yamazaki, Takahiro Yoshida, Yoshio Muroga, Ichiro Noda

Polymer Journal 31 ( 12 ) 1237 - 1242 1999年

¹³C NMR Relaxation of Poly (t-butyl crotonate) in Solution. Effects of β-Substitution on Local Chain Motions 査読

Shinichi Yamazaki, Eisaku Okada, Yoshio Muroga, Ichiro Noda, Akihiro Tsutsumi

Polymer Journal 31 ( 6 ) 542 - 549 1999年

C-13 NMR relaxation of iso-poly(2-vinylpyridinium chloride) in aqueous solution. Effects of electrostatic interactions on local chain dynamics 査読

S Yamazaki, E Okada, Y Muroga, Noda, I, A Tsutsumi

POLYMER JOURNAL 31 ( 7 ) 614 - 620 1999年

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：NATURE PUBLISHING GROUP

Measurements of C-13 spin-lattice relaxation times, T-1, and nuclear Overhauser effects, NOE, were carried out as a function of temperature at two magnetic fields for iso-poly(2-vinylpyridine) (iso-P2VP) in I,4-dioxane-d(8) and iso-poly(2-vinylpyridinium chloride) (iso-P2VPCl), in D2O to investigate the effects of electrostatic interactions on local chain dynamics. For main chain carbons of both polymers, the experimental T-1 and NOE data are in good agreement with the Dejean-Laupretre-Monnerie (DLM) model in the entire temperature range. It was found that the local conformational transitions of main chain and the libration are more restricted for iso-P2VPCl than iso-P2VP. For pyridyl ring carbons, the experimental data were reproduced by the models combining the DLM model and restricted ring rotations. The angular amplitude alpha of ring rotation of iso-P2VPCl is smaller than that of iso-P2VP. These results imply that both local motions of main chain and side chain are affected by the electrostatic interactions.

DOI： 10.1295/polymj.31.614

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