KOBUNSHI RONBUNSHU
Online ISSN : 1881-5685
Print ISSN : 0386-2186
ISSN-L : 0386-2186
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Volume 75, Issue 4
Displaying 1-8 of 8 articles from this issue
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Special Topic on Polymer Analysis II
Review Articles
  • Structural Studies of Polymer Nano-Assemblies in Solution by Scattering Techniques
    Takahiro SATO, Yan LI
    2018 Volume 75 Issue 4 Pages 293-336
    Published: July 25, 2018
    Released on J-STAGE: July 25, 2018
    Advance online publication: July 12, 2018
    DOIhttps://doi.org/10.1295/koron.2018-0003
    JOURNAL FREE ACCESS
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    Static light scattering, dynamic light scattering, and small-angle X-ray scattering are powerful tools to analyze structures of various polymer assemblies formed in solution. In this article, we briefly explain those experimental techniques along with their historical background, and review their applications to the following polymer solution systems: (1) associating homopolymer solutions, (2) aqueous solutions of the polyanion–polycation mixture forming polyion complex colloids, (3) block copolymer solutions forming polymer micelles of various morphologies, (4) aqueous solutions of amphiphilic random and alternating copolymers forming the flower micelle or flower necklace, and (5) aqueous solutions of the globular protein–surfactant mixture. Different scattering techniques are combined with other experimental and theoretical methods to provide more detailed structural information.
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Original Papers
  • Effect of Kneading and Composition on the Structure and Physical Properties of EPDM/PP Thermoplastic Elastomer
    Ryunosuke IWABUCHI, Daisuke NAGAI, Masaru YONEYAMA, Hiroki UEHARA, Tak ...
    2018 Volume 75 Issue 4 Pages 337-346
    Published: July 25, 2018
    Released on J-STAGE: July 25, 2018
    Advance online publication: May 17, 2018
    DOIhttps://doi.org/10.1295/koron.2017-0084
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    The effects of kneading time and composition of dynamic thermoplastic elastomer (TPV) composed of polypropylene (PP) and EPDM on the physical properties and structure of TPV are investigated. As a result of the tensile test, the breaking stress and the breaking strain increased as the kneading time became longer and PP ratio increased. The results of the thermal measurement showed that increasing kneading time did not change the melting point and the degree of crystallinity of PP, but decreased the crystallization temperature. Pulse NMR measurements indicated that the longer the kneading time, the more the interface component between PP and EPDM increased. The decrease in T1 of PP with kneading time was also confirmed from CPMAS NMR measurements, which indicates an increase of plasticized PP. From the fact that the PP component cannot be completely removed by solvent extraction, it was clarified that part of PP penetrated into the EPDM. SEM observation showed that the dispersion of EPDM slowly progressed as the amount of PP increased, and fibrils were formed. It was revealed that this fibril formation varies depending on the kneading time and composition, and a network of rubber components is formed by the formed fibrils, which influences rupture stress and fracture strain.
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  • Measuring the Temperature and Humidity Dependence of Gas Diffusivity in Building Coatings by Using a Using Thermal Desorption System
    Ryoma KITAGAKI
    2018 Volume 75 Issue 4 Pages 347-357
    Published: July 25, 2018
    Released on J-STAGE: July 25, 2018
    Advance online publication: June 15, 2018
    DOIhttps://doi.org/10.1295/koron.2018-0001
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    It becomes increasingly important to estimate the barrier performance of coatings used for buildings in proportion to the increasing demand of building longevity in recent years. However, the barrier performance of coatings for building use which is attached and mixed with various base materials is difficult to estimate by conventional methodologies. Therefore, a thermal desorption system (TDS) for estimating gas coefficients of permeability, solubility and diffusivity of coatings for building use has been applied and it’s validity has been confirmed. As a result, the TDS method has been confirmed to be almost compatible with the conventional differential-pressure method, and additionally, it has been confirmed that the gas transfer in coatings for building use is dependent of temperature, humidity and interaction among the present gas species, as in conventional polymer films. The free-volume in coatings for building use can be estimated by the obtained data.
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  • Characterization of High Molecular Weight Acrylamide-Based Copolymers by DOSY-NMR Using High Field-Gradients
    Kazuya WATANABE, Koichi UTE
    2018 Volume 75 Issue 4 Pages 358-362
    Published: July 25, 2018
    Released on J-STAGE: July 25, 2018
    Advance online publication: July 06, 2018
    DOIhttps://doi.org/10.1295/koron.2018-0005
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    Copolymers of [2-(acryloyloxy)ethyl]trimethylammonium chloride (AETAC) and acrylamide (AAm) having weight-average molecular weights (Mw’s) exceeding 10 million were analyzed by diffusion-ordered two-dimensional spectroscopy (DOSY) using high field-gradients (≤13 T/m). Distribution curves of the self-diffusion coefficient (D) were successfully obtained for the copolymers, and the D values at the peak top (Dp’s) correlated well with Mw as Dp = (1.86 × 10−8)×Mw–0.749. The distributions of D agreed fairly well with those determined by dynamic light scattering. The DOSY analysis revealed the molecular weight dependence of the chemical composition of the copolymers; the relative AETAC content increased with decreasing molecular weight.
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Original Papers
  • Thermal Transition Behavior of Liquid-Crystalline Cholesterol Derivative/Aliphatic Amine Complexes and Enthalpy Relaxation Characteristics in Their Glassy State
    Kazuki SUGIMURA, Koichi TSUDA, Hiroyuki ARAKAWA, Kyosuke SEIKE, Yoshih ...
    2018 Volume 75 Issue 4 Pages 371-380
    Published: July 25, 2018
    Released on J-STAGE: July 25, 2018
    Advance online publication: June 26, 2018
    DOIhttps://doi.org/10.1295/koron.2018-0007
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    Through DSC and polarized optical microscopy measurements, thermotropic phase behavior was examined for ionic complexes of cholesterol hydrogen phthalate (CHP) or succinate (CHS) with normal aliphatic amines (Cn-amines; carbon number n = 4–18), and for two types of complexes; one was composed of one cholesterol derivative and two different alkyl amines [i.e., CHP/(Cm,Cn)-amine and CHS/(Cm,Cn)-amine, m ≠ n] and the other consisted of two cholesteryls and one Cn-amine [(CHP,CHS)/Cn-amine]. Except for the cholesteryl complexes with shorter Cn-amine (n ≤ 6), all the complex salts easily formed a liquid-crystalline glass (smectic or cholesteric type) without crystallization and phase-separation after passing through the mesomorphic fluid state, when they were cooled from the respective isotropic melts. Enthalpy relaxation of these glassy materials, occurring during physical aging below their Tg, was followed as a function of the aging time and temperature, and the obtained data was analyzed in terms of a Kohlrausch-Williams-Watts function. Uniformity of the relaxation mode was quite high for the aged samples of CHP/Cn-amine (n = 10–18) forming a smectic liquid-crystalline glass, and a slow relaxation with diverse modes was observed for the mixed complexes, particularly for CHP/(Cm,Cn)-amine and CHS/(Cm,Cn)-amine.
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  • Synthesis of Particle Double-Network Gels by Redox Polymerization
    Katsuya KIKUCHI, Katsuhiko HIRANO, Kouichi KUROSAWA, Tetsuro IIJIMA, H ...
    2018 Volume 75 Issue 4 Pages 381-386
    Published: July 25, 2018
    Released on J-STAGE: July 25, 2018
    Advance online publication: June 12, 2018
    DOIhttps://doi.org/10.1295/koron.2018-0018
    JOURNAL FREE ACCESS
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    Particle double-network (P-DN) gels are one of the high-strength gels that are usually synthesized by photopolymerization. In this study, we synthesized P-DN gels by redox polymerization. To decide the ratio of the most suitable polymerization initiator and catalyst, we synthesized several kinds of P-DN gels by changing each ratio at a time, and performed compression tests. P-DN gels with a small amount of the polymerization initiator and catalyst showed high strength. In particular, P-DN gels with 0.2 mol% of the polymerization initiator and 0.1 mol% of the catalyst (percentages according to the monomer) showed a higher compression stress compared to the P-DN gels synthesized by photopolymerization. The moisture content of both gels was approximately equal. In addition, P-DN gels gelated after two hours for the redox polymerization process, which is shorter than for the photopolymerization process and thus advantageous for large-scale synthesis.
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