日本レオロジー学会誌
Online ISSN : 2186-4586
Print ISSN : 0387-1533
ISSN-L : 0387-1533
最新号
選択された号の論文の6件中1~6を表示しています
学会賞受賞講演論文
  • 山本 智
    原稿種別: 学会賞受賞講演論文
    2024 年 52 巻 5 号 p. 275-282
    発行日: 2024/12/16
    公開日: 2025/01/15
    ジャーナル フリー

    We have been intensively studying the network structure formation and rheology of thermosetting polymer epoxy resins by molecular dynamics simulations. Experiments indicated the existence of network structure heterogeneity in epoxy resins depending on the curing temperature, and a detailed rheological molecular picture of this heterogeneity was revealed. We have been also studying the effects of different chemical properties of the adherend surfaces on the curing shrinkage process and adhesive strength. The mechanism of the formation of nanoscale voids (free spaces) where water molecules can enter during the curing shrinkage process has been elucidated. Furthermore, it was found that the absorbed waters diffuse between the free spaces in a hopping manner. In addition, the effects of aggregation state and adsorbed water at the interface with amorphous silica and alumina substrates on the curing process were also investigated.

奨励賞受賞講演論文
  • Thanh-Tam Mai
    原稿種別: Award Lecture Article
    2024 年 52 巻 5 号 p. 283-290
    発行日: 2024/12/16
    公開日: 2025/01/15
    ジャーナル フリー

    This review describes our recent findings on stress-softening, known as the Mullins effect, and fracture behavior in polymer network-based soft materials under biaxial deformation. This study highlights contrasting energy dissipation mechanisms and anisotropic damage characteristics in filler-reinforced elastomers and double network hydrogels, attributing these differences to the distinct origins of internal damage in these materials. We also investigate crack properties, including strain energy release rates and local crack-tip strain fields, under various types of applied deformation. Additionally, we focus on the dynamics of crack propagation, particularly for the transition between subsonic and super-shear speeds and reveal the significant differences in crack-tip properties between these speed regimes. These findings offer valuable insights into the internal damage mechanisms and fracture behavior in soft materials induced by diverse deformations, enhancing the understanding necessary for material design and application.

  • 伊藤 麻絵
    原稿種別: 奨励賞受賞講演論文
    2024 年 52 巻 5 号 p. 291-295
    発行日: 2024/12/16
    公開日: 2025/01/15
    ジャーナル フリー

    Poly(methyl methacrylate) (PMMA) is one of the general glassy polymers and has high transparency. In this study, I have focused on the mechanical properties of PMMA doped with some metal salts. The effects of molecular interaction between PMMA molecules and the metal salts were quantitatively evaluated due to the viscoelastic properties of the salt-doped samples. Moreover, a kinetical constitutive equation was proposed for the effects of water absorption on the stress-strain behavior of PMMA doped with a salt at the different salt concentrations.

  • 林 幹大
    原稿種別: 奨励賞受賞講演論文
    2024 年 52 巻 5 号 p. 297-303
    発行日: 2024/12/16
    公開日: 2025/01/15
    ジャーナル フリー

    Cross-linking creates three-dimensional networks that significantly enhance the thermal, mechanical, and solvent-resistant properties of materials, making it a pivotal method for the preparation of functional polymer materials. In this article, the author summarizes our research focusing on dynamic network structures featuring reversible bond-exchange mechanisms, including supramolecular cross-links and dynamic covalent bonds. Unlike traditional chemically cross-linked polymers, these innovative materials exhibit unique relaxation behaviors in response to thermal and light stimuli, offering useful functions such as recyclability, healability, and reprocessability. A thorough understanding of fundamental properties is crucial for regulating these functions. Notably, the complex rheological properties of a recently developed class of dynamic covalent-bonded network materials known as vitrimers remain insufficiently understood. This article provides insights into tuning the relaxation properties of vitrimers and analyzes long-time scale rheology with a focus on the applicability and limitations of the time-temperature superposition principle, as well as deviations from the typical Williams-Landel-Ferry (WLF) dependence of shift factors.

総合論文
  • Atsuko Namiki
    原稿種別: Feature Article
    2024 年 52 巻 5 号 p. 305-311
    発行日: 2024/12/16
    公開日: 2025/01/15
    ジャーナル フリー

    The rheology of magma is complex and similar to that of polymers and suspensions. Most magmas are partial melts of natural rocks, consisting of silicate melts, crystals, and bubbles. A silicate melt has the structure of a 3D network of SiO4 tetrahedra whose rheology is approximated by a Maxwell fluid. The rheology of silicate melts depends on temperature, composition, and strain rate. Sufficiently large stress on the silicate melt causes rapid strain before structural relaxation, resulting in brittle fragmentation. The crystals and bubbles provide suspension characteristics to the whole magma. Crystals with a volume fraction close to the maximum packing fraction dramatically increase the effective viscosity of the magma. In contrast, bubbles increase and decrease the effective viscosity depending on strain rate. The effective viscosity of magma varies by orders of magnitude owing to various factors such as temperature, composition, and crystal fractions. Such wide-ranging magma rheology characterizes volcanic eruption styles. Low-viscosity magma can flow like a liquid underground and over the earth&spos;s surface as lava flows. By contrast, solid-like viscous magma fragments into small pieces in a brittle manner, causing explosive eruptions. Understanding the rheology of magma is crucial, as it significantly shapes our understanding of volcanic eruptions.

論文
  • Hiroki Kurahara, Keita Ando
    原稿種別: Original Article
    2024 年 52 巻 5 号 p. 313-321
    発行日: 2024/12/16
    公開日: 2025/01/15
    ジャーナル フリー

    We experimentally study viscous effects on spherical shock waves in glycerol-water solution. A spherical shock wave is generated through rapid expansion of plasma by focusing a nanosecond laser pulse (532 nm) of energy fixed at 1.66 ± 0.22 mJ into the solution with varying glycerol concentration. In the near field, the shock propagation is recorded by an ultra-high-speed camera with temporal resolution of 10 ns. The recorded images are used to obtain the shock evolution, allowing for constructing the shock pressure evolution with the Rankine-Hugoniot relation. It turns out that the plasma pressure is reduced as the solution gets more viscous with increasing the glycerol concentration; wave steepening effect is deemphasized in the more viscous solution, leading to slower decay of the near-field shock pressure. In the far field, the shock pressure is recorded by a hydrophone at 2 mm to 10 mm from the laser focus and compared to linear acoustic theories with or without viscous absorption. The comparison shows that for the case of higher glycerol concentration (say, beyond 80 wt%), the inviscid assumption will fail, meaning that the viscous theory needs to be used for more accurate prediction of the far-field shock pressure.

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