Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Akihiko Takada Last modified date:2021.12.02

Assistant Professor / Nano Scale Evaluation / Department of Advanced Device Materials / Institute for Materials Chemistry and Engineering

1. Akihiko Takada, Jun-ichi Kadokawa, Preparation of cellulosic soft and composite materials using ionic liquid media and ion gels., Cellulose,, 2021.10.
2. Masaru Mukai, Akihiko Takada, Ayumi Hamada, Tomoko Kajiwara and Atsushi Takahara,, Preparation and characterization of an imogolite/chitosan hybrid with pyridoxal-5'-phosphate as an interfacial modifier, RSC Advances, 10.1039/d1ra04774d, 11, 9, 2021.11.
3. Afsana M. Raka, A. Takada, K. Saadat Hossain, Effect of heat treatment on conformational and structural properties of sugar beet pectin, Carbohydrate Polymer Technologies and Applications,, 2, 100149, 2021.12.
4. Molecular Aggregation Structure of Notched Nylon 12 Film During Uniaxial Elongation.
5. Masaru Mukai, Mari Takahara, Akihiko Takada, Atsushi Takahara, Preparation of an (inorganic/organic) hybrid hydrogel from a peptide oligomer and a tubular aluminosilicate nanofiber, RSC Advances, 10.1039/d0ra09514a, 11, 9, 4901-4905, 2021.06.
6. Linlin Li, Akihiko Takada, Wei Ma, Shigenori Fujikawa, Miho Ariyoshi, Kosuke Igata, Maiko Okajima, Tatsuo Kaneko, Atsushi Takahara, Structure and Properties of Hybrid Film Fabricated by Spin-Assisted Layer-by-Layer Assembly of Sacran and Imogolite Nanotubes, Langmuir, 10.1021/acs.langmuir.9b03626, 36, 7, 1718-1726, 2020.02, A free-standing (biomacomolecule/synthetic inorganic nanotubes) hybrid film was fabricated through an alternative layer-by-layer (LBL) assembly of sacran and imogolite nanotubes. Sacran is a natural polysaccharide extracted from the cyanobacterium Aphanothece sacrum, while imogolite is a natural tubular aluminosilicate clay found in volcano ash. The hybrid film thickness increased linearly with the number of the bilayers, because of the interaction between the negatively charged surface of sacran and the positively charged surface of imogolite. UV-vis spectroscopy indicated that the LBL film exhibited good transparency. The surface morphology of the LBL film was smooth in the micrometer scale; many imogolite nanotubes were adsorbed onto the sacran layer, while no imogolite clusters were observed. Furthermore, the structure, stability, gas permeability, and mechanical properties of the LBL films were investigated..
7. Muhammad Abdul Haq, Yasuhiro Habu, Kazuya Yamamoto, Akihiko Takada, Jun ichi Kadokawa, Ionic liquid induces flexibility and thermoplasticity in cellulose film, Carbohydrate Polymers, 10.1016/j.carbpol.2019.115058, 223, 1-6, 2019.11, It is still challenging to melt-process cellulose. In this paper, we proposed a method for the formation of thermally processable flexible cellulose films via gelation from its solution in ionic liquid (1-butyl-3-methylimidazolium chloride; BMIMCl). Cotton, as a source of cellulose, was dissolved (5 wt%) in BMIMCl and subsequently placed in different amounts of water. The obtained ion gels were dried at 60 °C for 24 h; during drying process, water was removed while BMIMCl was retained. It was found that the amount of retained BMIMCl had a critical role in determining the mechanical properties of the films. It was suspected that the processing conditions altered the degree of crystallinity of cellulose in the films as evidenced by X-ray diffraction measurement. The ionic liquid, i.e., BMIMCl induced the plasticity into the films, so that thermal processability to different shapes became possible..
8. Linlin Li, Wei Ma, Akihiko Takada, Nobuhisa Takayama, Atsushi Takahara, Organic-Inorganic Hybrid Films Fabricated from Cellulose Fibers and Imogolite Nanotubes, Biomacromolecules, 10.1021/acs.biomac.9b00881, 20, 9, 3566-3574, 2019.09, Owing to the increasing environmental awareness, nanocellulose/natural clay composites with improved mechanical performance have attracted growing interest due to their eco-friendly properties. In this study, hybrid films composed of cellulose fibers (CFs) and imogolite nanotubes (natural aluminosilicate nanotubes) were fabricated. We mainly studied the structure, density, and properties of the hybrid materials. Specifically, the hybrid materials were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), a rheological test, and wide-angle X-ray diffraction (WAXD). The mechanical properties of the hybrid materials were measured by a tensile test, which demonstrated that the mechanical properties of the hybrid films were considerably improved by the addition of imogolite up to 1 wt %; meanwhile, the thermal-mechanical properties of the hybrid film were also enhanced..
9. Muhammad Abdul Haq, Yasuhiro Habu, Kazuya Yamamoto, Akihiko Takada, Jun Ichi Kadokawa, Inducing the crystallization in cotton cellulose ion gel films for enhanced mechanical properties, Fibers and Textiles for Value Creation in Connected Industries (Proc. 1st Fiber Society 2018 Spring Conference), 2018.01.
10. Akihiko Takada, Application of ionic liquid on natural polymer science and visualization of non-Newtonian flows, Sen'i Gakkaishi, 73, 5, 201, 2017.10.
11. Akihiko Takada, Jun Ichi Kadokawa, Fabrication and characterization of polysaccharide ion gels with ionic liquids and their further conversion into value-added sustainable materials, Biomolecules, 10.3390/biom5010244, 5, 1, 244-262, 2015.03, A review of the fabrication of polysaccharide ion gels with ionic liquids is presented. From various polysaccharides, the corresponding ion gels were fabricated through the dissolution with ionic liquids. As ionic liquids, in the most cases, 1-butyl-3-methylimidazolium chloride has been used, whereas 1-allyl-3methylimidazolium acetate was specifically used for chitin. The resulting ion gels have been characterized by suitable analytical measurements. Characterization of a pregel state by viscoelastic measurement provided the molecular weight information. Furthermore, the polysaccharide ion gels have been converted into value-added sustainable materials by appropriate procedures, such as exchange with other disperse media and regeneration..
12. Michihiro Shirakawa, Norifumi Fujita, Akihiko Takada, Seiji Shinkai, A Rubber Elastic Low-molecular-weight Organogel, Chemistry Letters, 43, 8, 1330-1332, 2014.08.
13. Akihiko Takada, Yoshiaki Takahashi, Hu Hao, Intrinsic Viscosiry of Pullulan in Ionic Liquid Solutions Studied by Rheometry, Nihon Reoroji Gakkaishi, 42, 3, 191-196, 2014.06.
14. Akihiko Takada, Yoshiaki Takahashi, Zhe Xu, Elastic Modulus of the Gel mad from interpenetrating Polymer Networks in Phase Separated State, Evergreen, 1, 1, 1-5, 2014.03.
15. Hu Hao, Akihiko Takada, Yoshiaki Takahashi, A study of Density for Pullulan/Ionic Liquid Solutions, Evergreen, 1, 1, 14-19, 2014.03.
16. Akihiko Takada, Koji Saeki, Shoichi Murata, Yukihiro Motoyama, Atsushi Takano, Hiroko Yamamoto, Yoshiaki Takahashi, Thermo-reversible solid-like and liquid-like behaviors of carboxyl-terminated telechelic poly(ethylene-butylene) neutralized by octadecylamine, Nihon Reoroji Gakkaishi, 10.1678/rheology.42.33, 42, 1, 33-38, 2014.03, Solid-like and liquid-like viscoelastic behaviors at low and high temperature, T, respectively, observed for carboxylterminated telechelic poly(ethyrene-butylene) (CTPEB) neutralized with octadecylamine ODA prepared by melt mixing are studied in relation with the structure examined by XRD, FT-IR, DSC and small angle neutron scattering. When the mole ratio of -NH2 and -COOH, NH2/COOH in CTPEB/ODA is 1.4 or higher, CTPEB/ODA was solid-like at 298K, while it was liquid-like having almost the same viscosity as CTPEB at 343K. The network structure formed at low T was easily fractured by small strain and cannot be reformed at low T. However, when the sample is annealed at 353K, cooled and kept for a few hours at T < 300K, the solid-like behavior is reproduced. It was concluded that the network formation at low T and its disappearance at high T for CTPEB/ODA is caused by non-crystalline association/ dissociation of C18 residues in ODA connected to CTPEB by ionic bond (NH3+COO-). Due to the small Mw of CTPEB, only longer chains (~ 1/3 of total chains) connected to ODA aggregates form network structure and sustain the constant G' in this system at low T..
17. Michihiro Shirakawa, Norifumi Fujita, Akihiko Takada, Seiji Shinkai, A rubber elastic low-molecular-weight organogel, Chemistry Letters, 10.1246/cl.140278, 43, 8, 1330-1332, 2014.01, A low-molecular-weight gel prepared from a Cu complex of a protoporphyrin IX derivative exhibits an unusual elastic behavior as revealed by rheological studies. It possesses rubber elasticity despite the formation of LMOG by noncovalent molecular stacking. This is due to the feature of the present system that the gel fibers behave similarly to covalent polymers without bundling..
18. Hao Hu, Akihiko Takada, Yoshiaki Takahashi, A study of density for pullulan/ionic liquid solutions, Evergreen, 10.5109/1440970, 1, 1, 14-19, 2014.01, Empirical relationships were obtained at temperatures 10-80 °C between density ρ and mass concentration C (wt%) of pullulan, which was used as a standard polymer in aqueous solutions containing two representative ionic liquids, l-butyl-3-methylimidamlium chloride and 1-ethyl-3-methylimidaolimn acetate. Water content effect on ρ was also examined. Pullulan was successfully dissolved into these ionic liquids without degradation, confirmed by the recovered samples. This indicates that pullulan is a suitable standard for ionic liquid soluble polymers. The empirical relationships provide easy conversion of C to concentration c (g/cm.3), which is essential for systematic studies of properties of pullulan in ionic liquids..
19. Zhe Xu, Yoshiaki Takahashi, Akihiko Takada, Elastic modulus of the gel made from interpenetrating polymer networks in phase separated state, Evergreen, 10.5109/1440968, 1, 1, 1-5, 2014.01, Interpenetrated polymer network (IPN) of gelatin (Git} and sodium polyalginate (Alg) is studied to prepare Alg gel, which is expected to be more uniform than that prepared directly at high added salt (NaCl) concentrations, Cs. The mixed solution and IPNs are homogeneous at lower Cs. It was found that the mixed solution get phase separated around Cs =0.35M. The gels made from the phase separated solution were also investigated. The roughness of Alg gels prepared via IPN and directly at higher Cs is almost the same. It can be summarized that the phase separation was brought by higher Cs and it is not suitable to prepare uniform Alg gels with Cs. It was pointed out that the Alg gels prepared with lower Cs via IPN shows narrower elastic modulus distribution than the higher ones..
20. Hao Hu, Akihiko Takada, Yoshiaki Takahashi, Intrinsic viscosity of pullulan in ionic liquid solutions studied by rheometry, Nihon Reoroji Gakkaishi, 10.1678/rheology.42.191, 42, 3, 191-196, 2014.06, Intrinsic viscosity [η] of nine pullulan samples with different molecular weights and narrow molecular weight distributions are obtained in 1-butyl-3-methylimidazolium chloride (BmimCl) and 1-ethyl-3-methylimidazolium acetate (EmimAc) from the Newtonian viscosities measured by oscillatory and steady shear flow in conventional rheometer for dilute solutions. For low molecular weight Mw samples, [η] in BmimCl and EmimAc almost coincide with that in aqueous solutions compared at the same Mw. The data at Mw < 30 kg/mol can be represented by Mw 0.5 dependence. The excluded volume effects observed in BmimCl and EmimAc at higher Mw are somewhat stronger than in aqueous solutions. Mark-Houwink-Sakurada equations for pullulan in BmimCl and EmimAc are determined in 20 kg/mol < Mw < 100 kg/mol. It is conclude that measurement of [η] by rheometer is a promising method for characterization of polymers in ionic liquids..
21. Arnab Dawn, Tomohiro Shiraki, Hiroshi Ichikawa, Akihiko Takada, Yoshiaki Takahashi, Youichi Tsuchiya, Le Thi Ngoc Lien, Seiji Shinkai, Stereochemistry-dependent, mechanoresponsive supramolecular host assemblies for fullerenes
A guest-induced enhancement of thixotropy, Journal of the American Chemical Society, 10.1021/ja211032m, 134, 4, 2161-2171, 2012.02, Self-assembly behaviors of a series of systems (G1, G2, and G3) possessing same organic building blocks based on a substituted anthracene have been investigated in decalin. G2 and G3 are dominated by head-to-tail (ht) and head-to-head (hh) type dimers of G1, respectively. G1 gives a thermoresponsive gel that behaves ideally, showing frequency-independent elastic and viscous moduli. Interestingly, G2 produces a thixotropic gel that shows the signature of structural relaxation, signifying the dynamic nature of the system. In contrast, G3 remains fluidlike. As investigated by scanning electron microscopy (SEM), in the assembly process of G2, first disklike nanoaggregates are formed, and in the second step these aggregates interact to construct the densely packed secondary assembly. A transition from secondary assembly to primary assembly under shear initiates the mechanoresponsive destruction of the gel. In the self-assembly process, G1 propagates in a one-dimensional fashion, whereas G2 and G3 can propagate in a two-dimensionional fashion. The same side orientation of the substituents in G3 facilitates the formation of a compact closed-shell-type structure, which results in the generation of isolated nanocrystals. The long-range weak interaction together with the capability of propagating in two dimensions is found to be essential for the construction of such a mechanoresponsive assembly. C 60 and C 70 could be incorporated successfully in G2 assembly to develop mechanoresponsive fullerene assemblies. The presence of fullerenes not only enhances the elastic properties of G2 but also intensifies the thixotropy. C 70 appears to be a superior guest in terms of property enhancement due to its better size fitting with the concave-shaped host..
22. T. Yamagishi, A. Ishizaki, T. Ogoshi, Y. Nakamoto, A. Takada, Control of molecular aggregation structure of a liquid crystalline cellulose derivative, Koubunshi Ronbunshu, 14, 705-708, 2011.01.
23. Tada Aki Yamagishi, Akihiko Ishizaki, Tomoki Ogoshi, Yoshiaki Nakamoto, Akihiko Takada, Control of molecular aggregation structure of a liquid crystalline cellulose derivative, KOBUNSHI RONBUNSHU, 10.1295/koron.67.705, 67, 12, 705-708, 2010.12, We have designed a new material with stable cholesteric structure by blending a cellulose derivative, (acetoxypropyl) cellulose (APC), with a thermoplastic polymer, poly (viny acetate) (PVAc). In the material obtained from THF solution, the compatibility between APC and PVAc was confirmed by differential scanning calorimetry (DSC) and infrared spectroscopy (IR). The materials showed colors arising from the selective reflection of circular polarized light. The colors depended on the composition of the materials. The material obtained from acetone solution showed phase separation into an APC rich phase and a PVAc rich phase, respectively. This indicated that the aggregation structure of APC/PVAc blends was affected by the preparation condition for materials. The FT IR results supported that the molecular aggregation structure was controlled by the hydrogen bonds between APC and PVAc polymer chains..
24. A. S. El-Khouly, Y. Takahashi, A. Takada, A. A. Safaan, E. Kenawy, Y. A. Hafiz, Characterization and mechanical properties of cellulose-graft-polyacrylonitrile prepared by using KMnO4/different acids as redox system, Nihon Reoroji Gakkaishi, 10.1678/rheology.38.133, 38, 3, 133-140, 2010.11, Cellulose-graft-polyacrylonitriles were prepared by using KMnO4/different acids redox system and the obtained samples were characterized by POM, SEM, 13C-NMR, XRD, TGA and their mechanical properties were investigated as a function of crystallinity degree (Cr %). In all cases, Cr decreased with increase of graft yield irrespective of acids species. Stress at break, strain at break and Young's modulus decreased with decreasing Cr %, which can be attributed to the increase of the amorphous region and the main chain rapture of cellulose. The mechanical properties of the samples prepared by strong acids became more poor than those for samples prepared by weak acids, indicating that more chain rupture occurred when strong acids are used..
25. Pritam Mukhopadhyay, Norifumi Fujita, Akihiko Takada, Takanori Kishida, Michihiro Shirakawa, Seiji Shinkai, Regulation of a real-time self-healing process in organogel tissues by molecular adhesives, Angewandte Chemie - International Edition, 10.1002/anie.201001382, 49, 36, 6338-6342, 2010.08, Say cheeeese! The thixotropic processes that occur in a naphthalenediimide-based organogel can be imaged in real time by TEM and AFM (see picture). The self-assembled 1D fibers disintegrate under mechanical stress and undergo a self-healing process during a resting time to reconstitute the 1D fibers..
26. A. S. El-Khouly, Yoshiaki Takahashi, Akihiko Takada, A. A. Safaan, E. Kenawy, Y. A. Hafiz, Characterization and thermal stability of cellulose-graft- polyacryloniytrile prepared by using KMnO4/citric acid redox system, Journal of Applied Polymer Science, 10.1002/app.31679, 116, 3, 1788-1795, 2010.05, An effective condition of graft polymerization of acrylonitrile onto cellulose fiber in large volume of KMnO4/citric acid aqueous solution was examined and the produced grafted copolymers were characterized by using SEM, NMR, FTIR, XRD, TGA, and DSC in comparison with component homopolymers. Graft yield, GY, obtained by simple weighting method was close to the value obtained by NMR analysis. Significant change of chemical structure in cellulose fiber, other than graft reaction, was not detected by NMR and FTIR measurements, whereas a decrease in the degree of crystallinity by the reaction was detected by XRD measurement. It was pointed out that thermograms for grafted samples resembles with that of cellulose at T < 370°C and become similar with that for polyacrylonitrile at T > 370°C and the mass of residue at 550°C is proportional to the content of polyacrylonitrile (GY) only. It is concluded that thermal decomposition of both polymers occurs almost independently in grafted polymers and thermal stability of cellulose fiber is not improved..
27. Amany S. El-Khouly, Yoshiaki Takahashi, Akihiko Takada, A. A. Safaan, El-Refaie Kenawy, and Y. A. Hafiz, Characterization and Thermal Stability of Cellulose-graft-Polyacryloniytrile Prepared by Using KMnO4/Citric Acid Redox System, J. Appl. Polym Sci., 116, 1788-1795, 2010.03.
28. Kamalesh Prasad, Masa aki Murakami, Yoshiro Kaneko, Akihiko Takada, Yoshifumi Nakamura, Jun ichi Kadokawa, Weak gel of chitin with ionic liquid, 1-allyl-3-methylimidazolium bromide, International Journal of Biological Macromolecules, 10.1016/j.ijbiomac.2009.05.004, 45, 3, 221-225, 2009.10, This paper reports the formation of weak gel of chitin with an ionic liquid, 1-allyl-3-methylimidazolium bromide (IL). When a mixture of 5% (w/w) chitin with IL was heated at 100 °C for 48 h, the clear liquid was obtained. The experimental process was observed by the CCD camera view and the SEM analysis. From a mixture of chitin with IL in the higher concentration (7%, w/w), a more viscous material, i.e., a gel-like material was obtained. The rheological evaluations showed that both 5% (w/w) and 7% (w/w) chitins with IL behaved as weak gels..
29. Hiroko Yamamoto, Ayako Himuro, Taisuke Matsumoto, Daisuke Noda, Akihiko Takada, Yukihiro Motoyama, Yoshiaki Takahashi, Crystal structure of H-ShapedAlkane H 3C(CH 2) 2} 2OHC(CH 2) 4COH{(CH 2) 2CH 3} 2 and its compatibility with high density polyethylene, Zairyo/Journal of the Society of Materials Science, Japan, 10.2472/jsms.58.1, 58, 1, 1-4, 2009.01, We synthesized a complex branched alkane (H-shaped) with two hydroxyl groups attached to branching points and studied its crystalline structure and also compatibility with high density polyethylene (PE). Results of DSC and X-ray diffraction on solution-crystallized and bulk-crystallized H-shaped alkanes gave same lattice constants for a triclinic type of crystal, a = 1.04nm, b = 1.27nm, c = 1.60nm, α = 95.7°, β = 91.6°, and γ= 109.4°. H-shaped/PE binary system showed a solid solution region 0.05 < Φ H < 0.40, where Φ H is the volume fraction of H-shaped alkane. On the other hand, in the region 0.46 < Φ H < 0.90, H-shaped and PE are considered to mix athermally in the liquid state and to present separately in this binary system, taking crystal structures different from each other..
30. Shoichi Murata, Akihiko Takada, Hiroko Yamamoto, Yoshiaki Takahashi, Viscoelastic Properties of Worm-like Micelle of Aluminum Tristearylate/Decahydronaphthalene, Nihon Reoroji Gakkaishi, 10.1678/rheology.36.191, 36, 4, 191-194, 2008.12, Temperature dependence of dynamic viscoelastic properties for 7 wt% solution of aluminum tristearylate (C18Al) in decahydronaphthalene (decalin), prepared by 2 hours heating at 130 oC and 1 day aging at room temperature, are examined. Shapes of dynamic moduli vs. frequency plots are similar to those of entangled polymer systems, implying that this system forms wormlike micelles. Temperature dependence of zero shear viscosity η o can be expressed by an Arrhenius type equation. The specific viscosities obtained at different temperature are almost constant. Plateau modulus GN gradually increases with increase of temperature T, and the values reduced by absolute temperature are almost constant. The structure examined by small angle neutron scattering and X-ray diffraction was practically the same at different T. Therefore, we conclude that as long as the sample preparation condition is maintained the same, the network structure of C18Al/decalin micelle is practically the same at different temperatures and the main relaxation process of the network is similar to entangled polymers, at least for limited conditions tested in this study..
31. Akihiko Takada, Kenta Imaichi, Yoshiaki Takahashi, Abnormal viscosity behaviour of ionic liquid 1-n-Butyl-3-methylimidazolium chloride, 15th International Congress on Rheology The XVth International Congress on Rheology - The Society of Rheology 80th Annual Meeting, 10.1063/1.2964605, 1447-1449, 2008.09, Effect of adding an inorganic salt, lithium chloride, and water on viscosity of an ionic liquid, 1-n-butyl-3-methylimidazolium chloride (BmimCl), was investigated by shear stress measurements with a rheometer. Shear rate dependence of viscosity showed shear thinning behaviour, which implies that some structure should exist in the liquid and the structure should change at high shear rates. Addition of LiCl enhances the viscosity of BmimCl. The logarithmic value of zero shear viscosity, η0, of BmimCl increases linearly and largely with increasing the added salt contents. The increasing rate of the viscosity by addition of LiCl was about ten times larger than that for aqueous solution of LiCl. When water is added into BmimCl, viscosity decreased. The increasing rate of the viscosity by addition of LiCl for BmimCl with about 5 wt% of water was almost the same as that for BmimCl without addition of water..
32. Yoshiaki Takahashi, Akihiko Takada, Kenta Imaichi, Yoshihumi Nakamura, Viscoelastic properties of cellulose in 1-buthyl-3-methylimidazolium chloride, 15th International Congress on Rheology The XVth International Congress on Rheology - The Society of Rheology 80th Annual Meeting, 10.1063/1.2964676, 318-320, 2008.09, Viscoelastic properties of cellulose in an ionic liquid, 1-buthyl-3-methylimidazolium chloride (BmimCl) are measured in dilute and semidilute concentration regions. Intrinsic viscosity obtained in the dilute region was successively used to make a reduced plot of viscosity-concentration relationship. At the highest concentration, plateau region was observed..
33. A Takada, K. Imaichi, T. Kagawa, and Y. Takahashi, Abnormal Viscosity Increment Observed for an Ionic Liquid by Dissolving Lithium Chloride, J. Phys. Chem. B., 112, 9660-9662, 2008.08.
34. Akihiko Takada, Kenta Imaichi, Tomoyasu Kagawa, Yoshiaki Takahashi, Abnormal viscosity increment observed for an ionic liquid by dissolving lithium chloride, Journal of Physical Chemistry B, 10.1021/jp800633x, 112, 32, 9660-9662, 2008.08, The effect of adding an inorganic salt, lithium chloride, and water on the viscosity of an ionic liquid, 1-n-butyl-3-methylimidazolium chloride (BmimCl), was investigated by shear stress measurements with a rheometer. The shear rate dependence of the viscosity showed shear thinning behavior, which implies that some structure should exist in the liquid and the structure should change at high shear rates. Addition of LiCl enhances the viscosity of BmimCl. The logarithmic value of zero-shear viscosity, η0, of BmimCl increases linearly and largely with increasing added salt content. The increasing rate of the viscosity by addition of LiCl was about 10 times larger than that for an aqueous solution of LiCl. When water is added into BmimCl, viscosity decreased. The increasing rate of the viscosity by addition of LiCl for BmimCl with about 5 wt % of water was almost the same as that for BmimCl without addition of water..
35. S. Murata, A. Takada, H. Yamamoto and Y. Takahashi, Viscoelastic Properties of Worm-like Micelle of Aluminum Tristearylate/Decahydronaphthalene, Nihon Reoloji Gakkaishi (J. Soc. Rheol. Japan), 36, 191-194, 2008.06.
36. Shoichi Murata, Akihiko Takada, Yoshiaki Takahashi, Structure and viscoelasticity of wormlike micellar solutions under steady shear flows, J. Soc. Rheol. Jpn., 35, 4, 185-189, 2007.12.
37. Solution Propeties of Cellulose solutions in an Ionic Liquid.
38. Shoichi Murata, Akihiko Takada, Yoshiaki Takahashi, Structure and viscoelasticity of wormlike micellar solutions under steady shear flows, Nihon Reoroji Gakkaishi, 10.1678/rheology.35.185, 35, 4, 185-189, 2007.11, Structure and viscoelastic properties of aqueous wormlike micellar solutions of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal) were investigated by rheological measurements, flow visualization using small dispersed particles and small-angle neutron scattering under steady shear flows. The concentrations of CTAB and NaSal were respectively fixed at 0.15 mol L -1, so as to show Maxwell type relaxation behavior in the linear mechanical response region. According to the stress response of steady shear flow measurements, shear rate regions were classified into three regions, i.e. (A) a Newtonian region (for γ̇ < γ̇l), (B) a stress plateau region (for γl̇< γ̇ < γḣ), which had a characteristic behavior of the shear-banding, and (C) a stress turnup region (for γ̇> γ̇h) where shear stress increased with γ̇ again. It was revealed that the fraction of the nematic phase flowing at γ̇h was proportional to the shear rate in the region B. The first normal stress difference, Nl, was approximately proportional to the shear rate in the region B, while it gradually decreased with increasing shear rates in the region C..
39. A. Takada, Solubility Evaluation of Cellulose in Ionic Liquid by Viscoelasticity, AIP Conference Proceedings, 1027, 318-320, 2007.10.
40. Thermotropic Liquid Crystals of Cellulose Derivatives.
41. Shoichi Murata, Hiroshi Hayashi, Akihiko Takada, Yoshiaki Takahashi, Change in structure and viscoelasticity of thread-like micelles under steady shear flow, 55th SPSJ Annual Meeting Polymer Preprints, Japan - 55th SPSJ Annual Meeting, 55, 1171, 2006, The change in structure and viscoelasticity of aqueous solutions of thread-like micelles of cetyltrimetylammonium bromide and sodium salicylate under steady shear flow were investigated by small angle neutron scattering and viscoelastic measurements. Two dimensional neutron scattering measurements showed that the same scattering profiles were observed for both vertical and horizontal directions at 1 sec -1 and above 200 sec -1. On the other hand, scattering intensity in the vertical direction was stronger than that in the horizontal direction at 10 ∼ 100 sec -1. In that shear rate region, shear stress was almost constant, while first normal stress difference was almost proportional to shear rate..
42. Kenichi Eguchi, Kazuo Sakurai, Isamu Kaneda, Yoshiko Hiwatari, Yoshiaki Takahashi, Akihiko Takada, Salt and surfactant concentration dependencies of the micelle structure consisting of a dual-surfactant, 55th Society of Polymer Science Japan Symposium on Macromolecules 55th SPSJ Symposium on Macromolecules, 55, 3236-3237, 2006, A dual-surfactant aqueous solution made from LES and AMPB has been commonly used for shampoos. We investigate the salt and surfactant concentration dependencies of the micelle structure using the dynamic viscoelastic measurement and small angle X-ray scattering (SAXS)..
43. Tomoyasu Kagawa, Akihiko Takada, Yoshiaki Takahashi, Solubility of cellulose in ionic liquid and its viscoelasticity, 55th Society of Polymer Science Japan Symposium on Macromolecules 55th SPSJ Symposium on Macromolecules, 55, 3137-3138, 2006, Cellulose is insoluble in both water and general organic solvents. Recently, it was reported that cellulose is soluble in certain kind of ionic liquids, which are non-volatile liquid phase organic salts at around room temperature. In this study, we report on the difference of the viscoelastic properties of cellulose solutions prepared by two different methods. The effects of the added salt (LiCl) on the dissolution of cellulose are also examined. It was concluded that cellulose can be uniformly dissolved in the ionic liquid when samples are prepared by addition of LiCl or keeping under reduced pressure at 130°C..
44. Shoichi Murata, Takashi Ohkame, Hiroko Yamamoto, Akihiko Takada, Yoshiaki Takahashi, Structure and viscoelasticity of alminium stearate in non-polar solvent, 55th Society of Polymer Science Japan Symposium on Macromolecules 55th SPSJ Symposium on Macromolecules, 55, 4437-4438, 2006, We investigated structure and viscoelasticity of alminium stearate in non-polar solvent of decalin. Alminium stearate formed thread-like linear aggregate in decaline and showed a viscoelastic behavior of transient network. Its viscoelastic behevior and structure changed at around 55°C. In high temperature region above 55°C, G″ showed clear minimum and G′ and G″ could be superposed on master curves by time-temperature conversion scheme. Below 60°C, however, G″ did not shows a clear minimum and G″ could not be superposed on a master curve in high frequency region. Small neutron scattering measurement showed that the linear aggregate had a longer correlation length and a larger thread diameter in high temperature region than in low temperature region..
45. Mitunori Maeda, Akihiko Takada, Yoshiaki Takahashi, Thermoplastic elastomer formed by telechelic polymer/stearyl amine complex, 55th Society of Polymer Science Japan Symposium on Macromolecules 55th SPSJ Symposium on Macromolecules, 55, 4435-4436, 2006, Thermoplastic elastomers were prepared by association between crystalline amines and telechelic polymer with carboxyl groups (CTPEB) at both ends. The crystalline moieties of stearyl amine could be form a crystalline or semicrystalline structure and associated with each other, which lead to the network formation of telechelic polymer. These compound showed the thermoplastic behavior. In order to obtain samples with higher transition temperature, compared with stearyl amine, we tried several method. N-(2-aminoethyl) octadecanamide (NAODAm) used as a crystalline amine with high melting temperature for its hydroxyl bond. The complex between CTPEB and NAODAm had transition temperature with about 70°C which is about 30°C higher than that of CTPEB/stearyl amime (C18A) complex region..
46. Akihiko Takada, Viscoelastic Network Formation by Ionic Complex Between Carboxyl Terminated Telechelic Polymer and Organic Amines, Theoretical and Applied Mechanics Japan, 10.11345/nctam.54.255, 54, 255-261, 2005.01, We studied complex formation between carboxyl teminated telechelic polymer and organic amines such as aromatic and aliphatic amines and their mechanical properties. It turned out that aliphatic amines can form ionic complexes with the telechelic polymer. On the other hand, aromatic amines and pyridines did not form ionic complex with the polymer. Remarkable increase in viscosity was observed for the complex between the polymer and an aliphatic amine with two amino groups. The complex compound could flow and behave a viscoelastic network, even although all carboxyl groups of the polymer formed ionic complexes with equilibrium amount of amino groups of a diamino compound to form highly entangled network of long polymer chains and ring chains formed by association of original chains. The activation energy of flow process of the ionic complex was larger than that of the original telechelic polymer, which indicates that they have different flow mechanism. The flow property of the ionic complex should come from recombination process of ionic associates between carboxyl and amino groups..
47. Keita Kuroiwa, Tomoko Shibata, Akihiko Takada, Norio Nemoto, Nobuo Kimizuka, Heat-Set Gel-like Networks of Lipophilic Co(II) Triazole Complexes in Organic Media and Their Thermochromic Structural Transitions, Journal of the American Chemical Society, 10.1021/ja037847q, 126, 7, 2016-2021, 2004.02, A novel class of thermally responsive supramolecular assemblies is formed from the lipophilic cobalt(II) complexes of 4-alkylated 1,2,4-triazoles. When an ether linkage is introduced in the alkylchain moiety, a blue gel-like phase is formed in chloroform, even at very low concentration (ca. 0.01 wt %, at room temperature). The blue color is accompanied by a structured absorption around 580-730 nm, which is characteristic of cobalt (II) in the tetrahedral (T d) coordination. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) of the gel-like phase confirms the formation of networks of fibrous nanoassemblies with widths of 5-30 nm. The observed widths are larger than a molecular length of the triazole ligand (ca. 2.2 nm) and they are consisted of aggregates of Td coordination polymers. Very interestingly, the blue gel-like phase turned into a solution by cooling below 25 °C. A pale pink solution is obtained at 0 °C. indicating the formation of octahedral (Oh) complexes. The observed thermochromic transition is totally reversible. The formation of gel-like networks by heating is contrary to the conventional organogels, which dissolve upon heating. Temperature dependence of the storage and loss moduli (G′ and G″) shows minima around at 27 °C, at which temperature they gave comparable values. On the other hand, G′ exceeds G″ both in the gel-like phase (temperature above 27 °C) and in the solution phase (temperature below 25 °C). These observations indicate that Td complexes are present as low-molecular weight species around at 25-27 °C. They are self-assembled to polymeric Td complexes by heating and form gel-like networks. Upon cooling the solution below 25 °C, Td complexes are converted to Oh complexes and they also self-assemble into oligomeric or polymeric species at lower temperatures. The observed unique thermochromic transition (pink solution → blue gel-like phase) is accompanied by an exothermic peak in differential scanning calorimetry (DSC), and is shown to be an enthalpy-driven process. The lipophilic modification of one-dimensional coordination systems provides unique solution properties and it would be widely applicable to the design of thermoresponsive, self-assembling molecular wires..
48. Syed A. Rahman, Akihiko Takada, Norio Nemoto, Viscoelasticity of potassium neutralized telechelic poly(ethylene-butylene) ionomer in non-polar solvent, Nihon Reoroji Gakkaishi, 10.1678/rheology.30.95, 30, 2, 95-102, 2002.01, Viscosity and viscoelasticity were measured for potassium neutralized telechelic poly(ethylene-butylene) ionomer, CTPEB-K, as well as the original polymer, CTPEB, in a non-polar solvent of decalin in a concentration range from dilute to semidilute regime. CTPEB-K was found to associate with each other even in the dilution limit. With increasing the polymer concentration, CTPEB-K solution showed a rapid increase in viscosity due to the formation of a huge cluster and further increase in the concentration lead to formation of a viscoelatic network with finite but quite high viscosity. The time-temperature superposition could be applied for the viscoelasticity of the network and the Arrhenius type of temperature dependence was observed. The viscoelastic network exhibited two or three relaxation modes. The fast mode may be assigned to the network rearrangement and the slow mode possibly to the cluster migration in the viscous fluid..
49. Yasuyoshi Shigematsu, Akihiko Takada, Norio Nemoto, Koh Hei Nitta, An instrument for simultaneous kinetic measurements of microscopic infrared dichroism and stress of inhomogeneous polymer thin films at constant elongation rate, Review of Scientific Instruments, 10.1063/1.1396666, 72, 10, 3927-3932, 2001.10, A new instrument has been built for a study on deformation mechanisms of inhomogeneous polymer thin films from simultaneous in situ kinetic measurements of microscopic infrared dichroism and stress at constant elongation rate. During elongation, the center position of the film is slightly adjusted manually by direct observation of the sample using the microscope so as to measure IR interferogram from the same rectangular area with a side from 20 to 600 μm. The average orientation angle θ(t) of the main chain to the draw direction is estimated from the function A(t) = (A - A)/(A + A) using a photoelastic modulator. Here A and A are the absorbances measured with radiation polarized parallel and perpendicular to the draw direction, respectively. True stress is calculated from nominal stress by correcting changes in film thickness as well as width accompanied by large deformation. Capability and limit of the instrument are examined in detail using two polypropylene films with different morphologies, one consisting of crystallites showing no gross morphology such as spherluites and another including only a huge spherulite embedded in the matrix..
50. Kazuki Koga, Akihiko Takada, Norio Nemoto, Dynamic light scattering and dynamic viscoelasticity of poly(vinyl alcohol) in aqueous borax solutions. 5. Temperature effects, Macromolecules, 10.1021/ma990493w, 32, 26, 8872-8879, 1999.12, Steady viscosity, dynamic viscoelasticity (DVE), and dynamic light scattering (DLS) measurements were made to study the effects of temperature, T, on association behaviors of poly(vinyl alcohol) (PVA) with weight-average degree of polymerization DPw = 350 in aqueous Borax solution. Intrinsic viscosity, [r/], monotonically decreased by 23% with a rise in T from 10 to 65 °C. At low T, enhancement in viscosity was observed with increasing polymer concentration, C, due to formation of viscoelastic network with the didiol complex as temporal cross-links, and the time-temperature superposition principle was found to be applicable for construction of a composite curve at each C. Those composite curves were further reduced so as to give one master curve. The system tended to lose its viscoelastic nature, when raising the temperature, toward a viscous solution owing to a decrease in the number of the didiol complexes as well as the shrinkage of the PVA chains. We found from analysis of DVE and DLS data that a clear boundary line between viscoelastic and viscous behaviors can be drawn on the T-C diagram using the temperature TN defined as the inflection point in a η vs T-1 plot for each C..
51. Yoshifumi Oyama, Akihiko Takada, Norio Nemoto, Depolarized dynamic light scattering measurement of rotational motion of rod-like molecules in solution under sinusoidal strain, Nihon Reoroji Gakkaishi, 10.1678/rheology.27.249, 27, 4, 249-250, 1999.01.
52. Akihiko Takada, Miki Nishimura, Akihiro Koike, Norio Nemoto, Dynamic light scattering and dynamic viscoelasticity of poly (vinyl alcohol) in aqueous borax solutions. 4. Further investigation on polymer concentration and molecular weight dependencies, Macromolecules, 31, 2, 436-443, 1998.01, Viscosity measurements are made on aqueous borax solutions of poly(vinyl alcohol) (PVA) samples over a wide range of PVA concentration, C, to examine the hydrodynamic properties of associated polymers compared to those of neutral polymers. The dynamic viscoelastic data are reanalyzed using a statistical-mechanical theory for elastically effective chains in transient gels developed by Tanaka and Ishida. The viscosity data are not superposed in the plot of viscosity against C[η] using the Huggins relationship, especially around and over a critical concentration, CN, at which the dynamical behaviors drastically change and an inflection point of a curve in the plot of the viscosity against C is located. On the other hand, when we assume that the chain dimension around CN is the unperturbed one, the viscosity data around CN is well-superposed on a curve in the plot of viscosity against C/C*up, where C*up is the overlapping concentration of the unperturbed chain. The inflection point of this composite curve is located at C/C*up = 1, which infers that CN corresponds to the overlapping concentration. All data of the density of elastically effective chains, νeff, are superposed on a curve in the plot of νefflν against (C - CN)/CN where ν is the density of polymer chains, which implies that CN should be regarded as a kind of gel point. Some discrepancies between the experimental data and the theoretical curve were observed, some of which cannot be explained using the pairwise association of PVA chains..
53. Akihiro Koike, Akihiko Takada, Norio Nemoto, Structure and dynamics of ovalbumin gels
II. Gels induced by heat treatment at 80°C, Polymer Gels and Networks, 10.1016/S0966-7822(98)00018-5, 6, 3-4, 257-271, 1998.01, Dynamic viscoelastic measurements were made on ovalbumin gels prepared by two different thermal denaturation methods for a study of their gel structures. Results are discussed in the light of the fractal concept developed for the critical gel structure of synthetic polymers at the sol-gel transition point. Especially, a role of added salt on association kinetics of denatured proteins as well as on the resulting gel structures are described in detail..
54. Kyoichi Nakamura, Masafumi Kiriyama, Akihiko Takada, Hideaki Maeda, Norio Nemoto, Structure and dynamics of ovalbumin gels
III. Solvent effect, Rheologica Acta, 36, 3, 252-261, 1997.05, Solvent effects on dynamical and thermal behaviors of ovalbumin (OVA) gels induced by thermal denaturation at high temperature of 160°C were studied from dynamic shear modulus measurement, shear creep and creep recovery measurement, and DSC measurement. Two organic solvents, glycerin (G) and ethylene glycol (EG), and their mixtures with water (W)(G/W and EG/W) were used as solvent for preparation of gels. Stable gels formed in pure glycerin took a fractal structure at OVA concentration C range of 15-45wt% at a temperature specific to respective C, whereas a fractal structure was not observed for gels prepared in EG, G/W, and EG/W. The results were consistent with thermal denaturation behaviors of OVA in these solvents. Morphologies of two gels prepared in water and glycerin were explored using high resolution SEM, which showed that a basic unit responsible for formation of OVA gels was spheres with a diameter ranging from 20 to 40 nm, being much larger than 5.6 nm of the diameter of native OVA, and a fractal structure was related to network formation accompanied by melting of those spheres..
55. Hideki Kitao, Akihiko Takada, Norio Nemoto, Dynamic viscoelasticity of telechelic polybutadiene lonomer solutions, Nihon Reoroji Gakkaishi, 10.1678/rheology1973.25.4_201, 25, 4, 201-202, 1997.01, We present results of dynamic viscoelastic measurements on toluene solutions of telechelic polybutadiene-magnesium ionomer, as one of model systems suitable for a study on structure and dynamics of associating polymers over a wide range of temperature T and polymer concentration C. T dependence of the viscosity is found to be expressed as the product of two contributions, one from local segmental motion and the other from the dissociation-association process of the end ionic groups with the activation energy, Ea=77kJ/mol..
56. Akihiko Takada, N. Nemoto, Dynamics of associating polymers in solution
Dynamic light scattering and dynamic viscoelasticity of poly(vinyl alcohol) in aqueous borax solution, Progress in Colloid and Polymer Science, 10.1007/BF01189517, 106, 183-187, 1997.01, We have studied the dynamics of poly(vinyl alcohol) (PVA) in aqueous borax solution by dynamic light scattering (DLS) and dynamic viscoelastic (DVE) measurements. DLS measurement showed the presence of two dominant modes with decaying rates of Γf and Γsf > Γs). Different dynamical behaviors were observed above and below a critical concentration, CN. The slow mode was manifested to be the diffusive mode for PVA concentration C < CN and the relaxation mode for C > CN. Dynamical correlation length, ξH, estimated from Γf exhibited a jump at CN with increasing C. Detailed analysis revealed the applicability of the dynamic scaling theory to Γs for C < CN and the presence of the dynamic coupling between concentration fluctuation and elastic stress of the transient network for C > CN. From these results, we drew the picture on a growing process of associating PVA chains to a temporally cross-linked network with increasing C and proposed that CN corresponded to the gel point of the chemically cross-linked gel in the short-time domain. The concept is found to be useful for interpretation of the concentration dependence of the plateau modulus..
57. T. Ohta, T. Zhang, A. Takada, Evaluation with B-value of the function of environmental humidity control of textiles, sen'i gakkaishi, 10.2115/fiber.52.5_234, 52, 5, 234-241, 1996.01, B-values of various moisture-absorbing textiles and usual interior materials such as lauan plywood were analyzed as a measure of the function of environmental humidity control, by measuring the continuous change of relative humidity accompaning with the periodic change of temperature in a closed vessel of 0.012 m3 including a textile or a usual interior material having a constant area or weight. The response of moisture-absorption (or -desorption) of each textile was quicker than that of lauan plywood for interior wall, so as to follow the change of relative humidity caused by the rapid change of temperature in a closed vessel. This is due to the markedly large specific surface area in a textile, concerning with the moisture-absorption (or -desorption), in comparison with that in a lauan plywood. The B-values determined at the constant area for each textile were lower than that of a lauan plywood, that is, the function of environmental humidity control of each textile was inferior to that of a lauan plywood. However, B-values at the constant weight for a cotton fabric. a woollen fabric, a rayon fabric and a solvron fabric were almost the same degree with that of lauan plywood. In B-values at the constant weight for these materials, the higher moisture-absorption led to the higher B-value. The highest moisture-absorption and the highest B-value were observed in the NF-38 non-woven fabric, 60 wt% of which was the high moisture-absorption fiber N. 38. These results show that the function of environmental humidity control of materials, having a large and different specific surface area, should be evaluated by B-value at the constant weight and that the textiles having a superior function of environmental humidity control, exceeding that of lauan ply wood, can be designed by controlling the weight/area of moisture-absorption textiles such as a cotton fabric..
58. Akihiko Takada, Takeshi Fukuda, Junji Watanabe, Takeaki Miyamoto, Akihiko Takada, Junji Watanabe, Orientation-Dependent Interactions in Polymer Systems. 5. Thermotropic Liquid Crystalline Transition of Tri-O-heptylcellulose, Macromolecules, 10.1021/ma00113a045, 28, 9, 3394-3400, 1995.04, Fairly narrow fractions of tri-O-heptylcellulose (THC) covering a wide range of degrees of polymerization (DP) were prepared and studied by viscometry and light scattering to determine the wormlike model parameters of the polymer to be q = 43.2 exp(-0.0050T) nm and ML = 880 nm-1, where q is the persistence length, ML is the shift factor, and T is the absolute temperature. The same fractions were studied with their thermal properties to determine the anisotropic-isotropic transition temperature Ti and transition entropy ΔS as a function of DP. Both Ti and ΔS increased with increasing DP to approach a limiting value for large enough DP. These trends were favorably compared with the predictions of the statistical models with the above-noted parameter values. It was shown that the main factor that causes the thermotropic transition and the chain-length dependence of Ti in bulk THC is the temperature-dependent flexibility of the polymer..
59. Takeshi Fukuda, Akihiko Takada, Yoshinobu Tsujii, Takeaki Miyamoto, Akihiko Takada, Orientation-Dependent Interactions in Polymer Systems. 4. Chain-Length Dependence of the Nematic-Isotropic Transition Behavior of Thermotropic Semiflexible Polymers, Macromolecules, 10.1021/ma00113a044, 28, 9, 3387-3393, 1995.04, The nematic-isotropic transition behavior of semiflexible polymers in the bulk was studied on the basis of three typical models of orientation-dependent interactions (the Onsager-Kimura-type mean-field model, the lattice version of the Onsager model, and the Maier-Saupe-type soft interaction model) and two polymer models (the wormlike chain and the freely jointed chain with randomly distributed joints). The critical value of x = q/D required to stabilize the nematic phase was evaluated as a function of m = L/q for various combinations of the models, where L, q, and D are the contour length, the persistence length, and the diameter, respectively, of the chain. Even though x and x, the value of x at L → ∞, strongly depended on the models, the predicted ln(x/x) vs m relations were reasonably model-insensitive, offering a hopefully quantitative interpretation for the known dependence of the transition temperature Ti on chain length. (Note that q and hence x is a function of temperature.) Like Ti, the enthalpy change of transition was predicted to increase with L, approaching a constant value for large L. This behavior originates in the conformational change of semiflexible polymers and is not a characteristic of rigid rodlike molecules..
60. Akihiko Takada, N. Ide, T. Fukuda, T. Miyamoto, K. Yamagata, J. Watanabe, Discotic columnar liquid crystals in oligosaccharide derivatives III. Anomeric effects on the thermo-mesomorphic properties of cellobiose octa-alkanoates, Liquid Crystals, 10.1080/02678299508032005, 19, 4, 441-448, 1995.01, The α-and β-anomers of cellobiose octa-alkanoates with purities higher than about 95 per cent were prepared from β -cellobiose by two simple esterification methods. The carbon number n of the acyl substituents ranged from 7 to 10 in both anomers. Both α -and β -anomers exhibited two types of discotic columnar phases (Dho and Dro), depending on n and temperature, but their phase diagrams were appreciably different. Generally, the α -anomers formed more stable mesophases than the β -anomers. In the Dro phase of the β -anomers, the column axis was tilted from the normal to the ‘disks’, while no such tilting was observed in the other phases..
61. Toshihiko Ohta, Akihiko Takada, Tomoko Yamamura, Akiyoshi Kawaguchi, Syozo Murakami, The ultra-drawing behaviour of ultra-high-molecular-weight polyethylene
comparison of the gel-like spherulite pressing method and the gel-casting method, polymer, 10.1016/0032-3861(95)95294-B, 36, 11, 2181-2187, 1995, Ultra-drawing behaviour has been studied by comparison of the gel-like spherulite pressing method and the gel-casting method using two kinds of specimens prepared from 2.0 wt% solution of ultra-high-molecular-weight polyethylene. The only major difference between the specimens is the cooling rate of solution. The influence of chain entanglement density in an undrawn specimen on the increase in strength and modulus with ultra-drawing has been discussed. The higher chain entanglement density of the undrawn specimen is the reason for the slopes of strength and modulus versus draw ratio being steeper in the gel-casting method. However, it was found that the differences in the above slopes between the two methods could not be explained by the changes in crystalline orientation and crystalline size with ultra-drawing..
62. Akihiko Takada, Kazunari Fujii, Junji Watanabe, Takeshi Fukuda, Takeaki Miyamoto, Chain-Length Dependence of the Mesomorphic Properties of Fully Decanoated Cellulose and Cellooligosaccharides, Macromolecules, 10.1021/ma00084a057, 27, 6, 1651-1653, 1994.11.
63. Toshihiko Ohta, Takao Wachi, Toshiki Nagai, Akihiko Takada, Yukiko Ikeda, Ohtsubo Takashi, Akiyoshi Kawaguchi, Ultra-drawing behaviour of ultra-high-molecular-weight polyethylene in the gel-like spherulite press method, polymer, 10.1016/0032-3861(93)90010-8, 34, 23, 4863-4867, 1993, Ultra-drawing behaviour in the gel-like spherulite press method has been investigated using two kinds of gel-like spherulites formed from 1.0 and 2.0 wt% solutions of ultra-high-molecular-weight polyethylene. The influence of chain entanglement density in a solution on the increase in strength and modulus with ultra-drawing is discussed. An equation predicting the maximum draw ratio from the drawing stress of the predrawn specimens is presented. It is concluded that the influence on the ultra-drawing behaviour of the spherulite size and lack of chain connection between spherulites can be ignored in this processing method..
64. Akihiko Takada, T. Fukuda, T. Miyamoto, Y. Yakoh, J. Watanabe, Columnar liquid crystals in oligosaccharide derivatives
II. Two types of discotic columnar liquid-crystalline phase of cellobiose alkanoates, Liquid Crystals, 10.1080/02678299208030401, 12, 2, 337-345, 1992.01, A series of cellobiose octaalkanoates, Cel-II-n (n is the carbon number of the alkyl chain), with n = 7–14 were prepared and their mesogenic properties examined by differential scanning calorimetry, optical polarizing microscopy and X-ray diffraction. All of these compounds form enantiotropic discotic columnar phases, in which the columns are built up by a regular stacking of the cellobiose moieties and are packed in a two dimensional lattice. Homologues with n = 9-14 form the Dho phase only whilst the compound with n = 7 forms the Dro phase. The n = 8 compound forms the Dho phase at higher temperatures and the Dro phase at lower temperatures. Structural parameters obtained from X-ray diffraction studies are presented for both phases..
65. Takeshi Fukuda, Akihiko Takada, Takeaki Miyamoto, Orientation-Dependent Interactions in Polymer Systems. 1. Segmental Orientation in Weakly Deformed Systems, Macromolecules, 10.1021/ma00023a023, 24, 23, 6210-6214, 1991.11, The effects of orientation-dependent interactions on the segmental orientation in weakly deformed polymer systems were reexamined on the basis of lattice theories and gas-of-rods theories. Both the freely jointed chain and the wormlike chain were considered as polymer models. It was shown in a somewhat general fashion that the orientation-dependent excluded-volume effect or packing effect could give rise to a considerable amount of excess orientation over that predicted in the absence of such an effect. For a dry system of freely jointed chains comprising rodlike segments of axial ratio 2, for example, the relative excess orientation was estimated to range roughly from 30 to 100%, depending on the theories. This value of the axial ratio seems to approximate the flexibilities of common vinyl polymers, and in this context, the volume effect would never be a minor one even for the “flexible” class of polymers. The nature of and the differences among the various statistical models were discussed in some detail..
66. T. Itoh, A. Takada, T. Fukuda, T. Miyamoto, Y. Yakoh, J. Watanabe, Columnar liquid crystals in oligosaccharide derivatives
I. discotic columnar liquid crystals in cellobiose octadecanoate and cellotriose hendecadecanoate, Liquid Crystals, 10.1080/02678299108035499, 9, 2, 221-228, 1991.01, Cellobiose octadecanoate and cellotriose hendecadecanoate were synthesized and their mesophase properties were studied. Both ester derivatives show enantiotropic mesophases in the temperature region below 100°C. From the observations of microscopic texture and X-ray pattern, the mesophase was found to be of the hexagonal columnar, in which the column is built up by a periodic stacking of the cellobiose or cellotriose skeleton and packed into a two-dimensional hexagonal lattice. The mesophase is thus similar to the hexagonal ordered columnar (Dho) phase in a class of discotics, indicating that cellobiose and cellotriose moieties can work as discotic mesogens..
67. Takeshi Fukuda, Makoto Sugiura, Akihiko Takada, Takahiro Itoh, Yung Dae Ma, Masahiko Minoda, Takeaki Miyamoto, Thermotropic liquid crystals based on oligosaccharides, sen'i gakkaishi, 10.2115/fiber.47.8_452, 47, 8, 452-455, 1991.01, Acylation or regio-selective alkylation of cello- and/or chito-oligosaccharides provides a new family of thermotropic liquid crystals. Some of the mesophase textures and thermal properties exhibited by these compounds were presented..
68. Takeshi Fukuda, Yung Dae Ma, Keiji Kubo, Akihiko Takada, Free-radical copolymerization VII. reinterpretation of velocity-of-copolymerization data, Polymer Journal, 10.1295/polymj.21.1003, 21, 12, 1003-1009, 1989.12, Velocity-of-copolymerization data available in the literature were reinterpreted on the basis of the current notions that the penultimate-unit effect with respect to absolute values of propagation rate constant (but not with respect to the monomer reactivity ratios) is a general rule, and that the termination step is diffusion-controlled, i.e., normal. By making a few simplifying approximations, a new velocity equation was derived, which was found to describe experimental data generally better than the classical equation based on the terminal propagation model with a single adjustable parameter φ, the cross-termination factor. The single adjustable parameter s included in the new equation, which measures the penultimate-unit effect, was found to have a strong correlation with the monomer reactivity ratios such that the smaller r1r2, the smaller is s, i.e., the more significant is the penulimate-unit effect. This result is in support of the relation r1r2=s1s2 suggested by the phenomenological theory [T. Fukuda et al., Makromol. Chem., Rapid Commun., 8, 495 (1987)]..