研究者詳細 - 増渕　雄一

Slip-link simulations of long-fiber networks under uniaxial compression 招待有り査読有り国際誌 Open Access

Yuichi Masubuchi

Transport Phenomena 2026年6月

新規シリコーンオイル増粘剤の開発と特性評価査読有り国際誌 Open Access

坂西裕一, 小林弘季, 櫻井優吏, 増渕雄一

日本化粧品技術者会誌 60 巻 ( 2 ) 頁： 81 - 88 2026年6月

担当区分：最終著者記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：日本化粧品技術者会

シリコーンオイルは，その感触，塗布性，高い透明性から化粧品に広く利用される。しかし，高粘度製剤やゲル化において，他の成分との相溶性や透明性を維持しつつ効果的な増粘を実現することは課題である。本研究は，これら課題を克服し，高い増粘性と優れた透明性を両立する新規シリコーンオイル増粘剤の開発を目的とし，炭化水素鎖を有する新規アミド変性シリコーンを合成した。増粘メカニズム解析の結果，本増粘剤がシリコーンオイル中で逆ミセル様の凝集構造を形成し，シリコーン主鎖を介してネットワーク構造を構築することが示された。このメカニズムにより，ネットワーク内に油性成分が均一に取り込まれ，高い透明性と均質な粘性が実現された。開発した増粘剤は，ジメチルポリシロキサンや環状シリコーンを含む多様なシリコーンオイルに対し，従来の増粘剤では困難であった増粘効果と透明性を同時に付与できることを実証した。これらの知見は，増粘剤設計の新たな指針を提供し，化粧品，医薬品，工業分野における広範な応用可能性を示唆し，シリコーンオイル基盤製剤の進歩に貢献すると考えられる。

DOI： 10.5107/sccj.60.81

Developments in multichain coarse-grained models for entangled polymer dynamics 招待有り査読有り国際誌 Open Access

Masubuchi, Y

POLYMER JOURNAL 2026年6月

担当区分：筆頭著者,　最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Polymer Journal

This review describes the development and applications of multichain coarse-grained simulations for entangled polymer dynamics. The mean-field tube model has long served as the standard paradigm for describing the many-body entanglement problem as the motion of a single chain in a static field; it faces intrinsic limitations when spatial correlations, fluctuations, and complex topological rearrangements are addressed. To overcome these limitations, “multichain” approaches—specifically, the primitive chain network and multichain slip-spring models—were developed. These simulations explicitly resolve the force balance and topological coupling between multiple chains in three-dimensional space. This review covers the primitive chain network model, which emphasizes real-space force balance, and the multichain slip-spring model, which is derived from a well-defined free energy functional. Linear and nonlinear rheology predictions are discussed, along with molecular mechanisms such as constraint release and stretch/orientation-induced reductions in friction. Extensions to branched polymers, wall-slip phenomena, and network polymers are also mentioned.

DOI： 10.1038/s41428-026-01206-0

A toy model for the cycle rank dependence of stretch at break in phantom chain network simulations 招待有り査読有り国際誌 Open Access

Masubuchi, Y

JOURNAL OF NON-NEWTONIAN FLUID MECHANICS 349 巻 2026年6月

担当区分：筆頭著者,　最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Non Newtonian Fluid Mechanics

The relationship between the topological architecture of polymer networks and their macroscopic rupture remains a fundamental challenge in polymer physics. Recent coarse-grained simulations have revealed that the dependence of stretch at break (λ<inf>b</inf>) on node functionality and reaction conversion can be unified into a universal master curve when plotted against the cycle rank density (ξ). However, a theoretical derivation explaining this universality has been lacking. This study proposes a simple mechanical model to describe the ξ-dependence of λ<inf>b</inf>. The polymer network is modeled as a mechanical system consisting of a sequence of springs representing localized, highly stretched strands and the surrounding unstretched network. By relating the stiffness contrast between these regions to the network connectivity defined by ξ, an analytical expression for the stretch at break is derived: λ<inf>b</inf>−1∝(3ξ+6)/(3ξ+2). The proposed model is validated against phantom chain simulations using both Gaussian and finite extensibility (FENE) springs. The theoretical prediction shows reasonable agreement with simulation data, providing a physical basis for the phenomenological universality observed in polymer network rupture.

DOI： 10.1016/j.jnnfm.2026.105620

Primitive chain network simulations of the creep of entangled polymers 招待有り査読有り国際共著 Open Access

Yuichi Masubuchi, Giovanni Ianniruberto, and Giuseppe Marrucci

Discover Polymers 3 巻頁： 3 2026年1月

The Hypoexponential Form for the Fiber-length Distribution in Thermoplastic Composites Revisited: Finite Initial Length, Cascade Fracture, and Its Mechanistic Status 招待有り査読有り国際誌 Open Access

Yuichi Masubuchi

Open Transport 2026年1月

Relation between Extensional Viscosity and Polymer Conformation in Dilute Polymer Solutions 査読有り国際誌 Open Access

KoIDE, Y; Ishida, T; Uneyama, T; Masubuchi, Y

NIHON REOROJI GAKKAISHI 54 巻 ( 2 ) 頁： 85 - 93 2026年

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nihon Reoroji Gakkaishi

We investigate extensional viscosity and polymer conformation in dilute polymer solutions under uniaxial extensional flow using dissipative particle dynamics simulations. At high extension rates, polymers are significantly stretched by extensional flows, and the extensional viscosity growth function exhibits strain hardening. To reveal their quantitative relation, we adopt an analysis method based on the Rouse-type model. We demonstrate that the extensional viscosity growth function is determined by the instantaneous gyration radii in the parallel and perpendicular directions to the extensional direction and their time derivatives. Our approach also provides a framework to describe the steady-state extensional viscosity of dilute polymer solutions for various chain lengths and concentrations in terms of the polymer gyration radius.

DOI： 10.1678/rheology.54.85

A Review on Molecular Simulations for the Rupture of Polymer Networks 招待有り査読有り Open Access

Yuichi Masubuchi, Takato Ishida, Yusuke Koide, and Takashi Uneyama

Science and Technology of Advanced Materials 26 巻 ( 1 ) 頁： 2587391 2025年12月

Influence of stretching boundary conditions on fracture in phantom star polymer networks: From volume to cross-sectional area conservation 招待有り査読有り国際誌 Open Access

Masubuchi, Y; Ishida, T; Koide, Y; Uneyama, T

POLYMER 340 巻頁： 129280 2025年12月

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

This study systematically investigates the effect of stretching boundary conditions—ranging from conservation of cross-sectional area to conservation of volume—on the rupture behavior of phantom star polymer networks using energy-minimizing coarse-grained molecular simulations. By continuously varying the deformation parameter, the simulations reveal that true stress and rupture characteristics, such as strain and stress at break and work for rupture, systematically decrease as the boundary condition approaches cross-sectional area conservation. In contrast, nominal stress and the corresponding rupture characteristics exhibit near-independence from boundary conditions, indicating that bond tension remains largely unaffected for phantom networks under the examined conditions. These results clarify that volume expansion primarily drives deviations in true stress and highlight a critical distinction between true and nominal stress-strain definitions. The difference between true and nominal stress-strain relations also affected the scaling exponent for strand length dependence on stretch at break. The findings stress the importance of specifying both deformation boundary conditions and stress-strain definitions in polymer network simulations for accurate interpretation of mechanical properties.

DOI： 10.1016/j.polymer.2025.129280

Steady-State Extensional Viscosity of Wormlike Micellar Solutions via Dissipative Particle Dynamics Simulations 査読有り国際誌 Open Access

Koide, Y; Ishida, T; Uneyama, T; Masubuchi, Y

MACROMOLECULES 58 巻 ( 22 ) 頁： 12039 - 12051 2025年11月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Macromolecules

We investigate the steady-state extensional viscosity of wormlike micellar solutions using dissipative particle dynamics simulations. As the extension rate increases, the steady-state extensional viscosity initially increases and subsequently decreases after reaching a maximum, as observed in experiments. We reveal that this nonmonotonic behavior arises from the competition between micellar stretching and scission under uniaxial extensional flow. We further propose a relation that connects the extensional viscosity to micellar structures and kinetics. This relation provides a unified description of the extensional viscosity of unentangled wormlike micellar solutions for various temperatures, concentrations, and extension rates.

DOI： 10.1021/acs.macromol.5c01993

Coarse-grained molecular dynamics simulations for oxidative aging of polymers under various O2 concentrations 査読有り国際誌

Ishida, T; Haremaki, K; Koide, Y; Uneyama, T; Masubuchi, Y

POLYMER DEGRADATION AND STABILITY 239 巻 2025年9月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Polymer Degradation and Stability

Modeling of polymer oxidative aging has been actively studied since the 1990s. Insights from these studies suggest that the transport of oxygen and radicals significantly influences aging heterogeneity, alongside chemical reaction kinetics. A recent simulation study [Ishida et al., Macromolecules, 56(21), 8474-8483, 2023] demonstrated that mesoscale heterogeneity arises when the H-abstraction reaction occurs faster than the relaxation times of polymer chains. In this study, the simulations were extended by modeling the rate of oxygen addition to polymer radicals (k<inf>2</inf>) to reflect the effects of the O₂ concentration. In this work, polypropylene was chosen as a representative example of the target polymer. Three key aspects of oxidative aging behavior were found to be influenced by the O<inf>2</inf> addition rate: (i) reaction kinetics, (ii) the degree of heterogeneity, and (iii) amount of crosslinking. Namely, reducing O<inf>2</inf> concentration slows the conversion of polymer radicals into H-abstractable peroxyl radicals. This deceleration delays H-abstraction reactions, increases the number of polymer radicals, and promotes crosslinking reactions between two polymer radicals.

DOI： 10.1016/j.polymdegradstab.2025.111404

Primitive chain network simulations of double peaks in viscosity growth curves of densely branched pom-pom polymer melts in fast shear flows 査読有り国際共著国際誌

Masubuchi, Y; Schussmann, MG; Hyun, K; Wilhelm, M; Hirschberg, V; Ianniruberto, G; Marrucci, G

RHEOLOGICA ACTA 64 巻 ( 6-7 ) 頁： 263 - 271 2025年7月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Rheologica Acta

Despite many attempts, the molecular mechanism of the nonlinear viscoelastic response of polymeric liquids in fast shear flows has not yet been fully elucidated. In this study, we examined the viscosity growth curves for a few well-characterized, nearly monodisperse, densely branched pom-pom polystyrene melts. The viscosity growth curves exhibit double peaks rather than the widely reported (for most polymer melts) single peak. To investigate the underlying molecular mechanism responsible for the observed behavior, we conducted primitive chain network (multi-chain sliplink) simulations, and found that the first and second peaks correspond to arm orientation and backbone stretch, respectively. We further observed that backbone stretch is reduced by coherent molecular tumbling at the flow start-up, and hence the second peak intensity comes out comparable to that of the orientation-induced first peak. In our sample, the number of backbone entanglements is small, so the mechanism of branchpoint withdrawal does not play a significant role.

DOI： 10.1007/s00397-025-01502-1

Persistence Length and Plateau Modulus of Semiflexible Entangled Polymers in Primitive Chain Network Simulations 査読有り国際誌

Masubuchi Y., Tassieri M., Ianniruberto G., Marrucci G.

Nihon Reoroji Gakkaishi 53 巻 ( 3 ) 頁： 119 - 125 2025年6月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nihon Reoroji Gakkaishi

The relationship between the plateau modulus (G<inf>0</inf>) and the persistence length (L<inf>p</inf>) of entangled semiflexible polymers is still uncertain. Some previous theoretical models have predicted that G<inf>0</inf> decreases with increasing L<inf>p</inf>, while experiments indicated the opposite. In this study, we extend the primitive chain network (PCN) model to incorporate bending rigidity at the scale of the entanglement length, consistently with the coarse graining of the model. Simulations investigate the effects of rigidity (and of molecular weight) on chain conformation and relaxation modulus. Our results reveal a relationship described as G<inf>0</inf> ~ L<inf>p</inf>2/3, indicating that G<inf>0</inf> increases with increasing L<inf>p</inf>, consistently with experiments. It should be considered, however, that implicit in our simulations is the condition that the entanglement length is kept fixed with changing L<inf>p</inf>

DOI： 10.1678/rheology.53.119

Phantom Chain Simulations for the Fracture of Star Polymer Networks on the Effect of Arm Molecular Weight 査読有り国際誌

Masubuchi, Y

MACROMOLECULES 58 巻 ( 12 ) 頁： 6399 - 6405 2025年6月

担当区分：筆頭著者,　最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Macromolecules

This study investigated the fracture of star polymer networks made from pre-polymers with various arm molecular weights in the range, 2 ≤ N<inf>a</inf> ≤ 20, for node functionalities 3 ≤ f ≤ 8 and conversion ratios 0.6 ≤ φ<inf>c</inf> ≤ 0.95 by phantom chain simulations. The networks were created via end-linking reactions of star polymers dispersed in a simulation box with a fixed monomer density ρ = 8. The resultant networks were alternatively subjected to energy minimization and uniaxial stretch until the break. The stretch at the break, λ<inf>b</inf>, depended on the strand molecular weight N<inf>s</inf> = 2N<inf>a</inf> + 1 with a power-law manner described as λ<inf>b</inf> ∼ N<inf>s</inf>0.67, consistent with the experiment. However, the strand length before stretch is proportional to N<inf>s</inf>0.5, which does not explain the observed N<inf>s</inf>-dependence of λ<inf>b</inf>. The analysis based on the non-affine deformation theory does not interpret the phenomenon either. Instead, the increase of normalized pre-polymer concentration concerning the overlapping concentration with increasing N<inf>s</inf> explains the result through a rise in the fraction of broken strands.

DOI： 10.1021/acs.macromol.5c00475

Nonmonotonic concentration dependence of the self-diffusion coefficient of surfactants in wormlike micellar solutions 査読有り国際誌

Koide, Y; Ishida, T; Uneyama, T; Masubuchi, Y

JOURNAL OF CHEMICAL PHYSICS 162 巻 ( 17 ) 2025年5月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Chemical Physics

We investigate the concentration dependence of surfactant diffusion in wormlike micellar solutions using dissipative particle dynamics simulations. The simulations show that the self-diffusion coefficient of surfactants exhibits a nonmonotonic dependence on the surfactant concentration, as observed in previous experiments. We quantitatively reveal that this nonmonotonic behavior results from the competition between micellar center-of-mass diffusion and surfactant diffusion within micelles by decomposing the mean-square displacement of surfactants into the corresponding contributions. Furthermore, our detailed analyses demonstrate how the competition between the two diffusion mechanisms is governed by the aggregation number distribution, the dynamics of individual surfactants and micelles, and the kinetics of micellar scission and recombination.

DOI： 10.1063/5.0266470

Prediction of induced fluxes in reverse nonequilibrium molecular dynamics 査読有り国際誌

Oishi, T; Koide, Y; Ishida, T; Masubuchi, Y; Uneyama, T

JOURNAL OF CHEMICAL PHYSICS 162 巻 ( 5 ) 2025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：Journal of Chemical Physics

Reverse nonequilibrium molecular dynamics (RNEMD) simulations impose a flux by swapping the velocities of two particles. This method allows for the calculation of transport coefficients, such as thermal conductivity and viscosity. The relation between the induced fluxes and the control parameters of RNEMD (such as the time interval between successive swap events) is not clear. Thus, trial-and-error is required to realize the desired fluxes in RNEMD simulations. In this study, we develop a theoretical framework using extreme value statistics to estimate the relation between the time interval and the resulting induced fluxes. Our RNEMD simulations, conducted with varying time intervals, confirm that the theoretical predictions are quantitatively consistent with the simulation results when the time interval exceeds the momentum relaxation time. Our RNEMD simulations also show that our theoretical predictions, which are valid for a large number of particles for swap candidates, work well even for a relatively small number of particles for swap candidates. These findings demonstrate that the induced fluxes can be reliably estimated, providing a valuable tool for selecting appropriate RNEMD parameters for simulations.

DOI： 10.1063/5.0236799

Direct Observation of the Compression Behavior of Polystyrene Microbeads in a Diamond Anvil Cell 査読有り国際誌 Open Access

Moriguchi, H; Niwa, K; Hasegawa, M; Koide, Y; Ishida, T; Uneyama, T; Masubuchi, Y

NIHON REOROJI GAKKAISHI 53 巻 ( 5 ) 頁： 209 - 213 2025年

Brownian simulations for fracture of star polymer phantom networks 招待有り査読有り国際誌

Masubuchi, Y; Koide, Y; Ishida, T; Uneyama, T

POLYMER JOURNAL 2024年11月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Polymer Journal

According to a recent simulation study [Masubuchi et al., Macromolecules, 56, 9359 (2023)], the cycle rank plays a significant role in determining the fracture characteristics of network polymers. However, the previous studies considered only energy-minimized networks without including the effects of thermal agitation. To address this gap, this study conducted Brownian dynamics simulations at various stretch rates. The results showed that even with Brownian motion, the strain and stress at break obtained for different node functionalities and conversion ratios exhibited master curves when plotted versus the cycle rank. These master curves depend on the strain rate, indicating that the strain and stress at break decrease with decreasing strain rate. The curves are qualitatively similar to those observed in energy-minimized simulations, even though the competition among Brownian motion, elongation, and bond scission affects the fracture process.

DOI： 10.1038/s41428-024-00992-9

Reverse Nonequilibrium Molecular Dynamics Simulations of a Melt of Kremer-Grest Type Model under Fast Shear 査読有り国際共著国際誌

Oishi, T; Koide, Y; Ishida, T; Uneyama, T; Masubuchi, Y; Müller-Plathe, F

JOURNAL OF CHEMICAL THEORY AND COMPUTATION 20 巻 ( 21 ) 頁： 9666 - 9672 2024年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Chemical Theory and Computation

Although the reverse nonequilibrium molecular dynamics (RNEMD) simulation method has been widely employed, the range of applicability is yet to be discussed. In this study, for the first time, we systematically examine the method against an unentangled melt of the Kremer-Grest type chain. The simulation results indicate that as the shear rate increases, the temperature and density become inhomogeneous. However, the average viscosity remains consistent with the results obtained using the SLLOD method under homogeneous temperature and density. We also confirm that the temperature-density inhomogeneity does not significantly affect polymer conformation.

DOI： 10.1021/acs.jctc.4c01007

Phantom chain simulations for the fracture of star polymer networks with various strand densities 招待有り査読有り国際誌

Masubuchi, Y; Ishida, T; Koide, Y; Uneyama, T

SOFT MATTER 20 巻 ( 36 ) 頁： 7103 - 7110 2024年9月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Soft Matter

Despite many attempts, the relationship between the fracture and structure of polymer networks is yet to be clarified. For this problem, a recent study on phantom chain simulations [Y. Masubuchi et al., Macromolecules, 2023, 56, 9359-9367.] has demonstrated that the fracture characteristics obtained for polymer networks with various node functionalities and conversion ratios lie on master curves if they are plotted against cycle rank, which is the number of closed loops in the network per network node. In this study, we extended the simulation to the effect of prepolymer concentration c on the relationships between the cycle rank and fracture characteristics within the concentration range of 1 ≲ c/c* ≲ 10, concerning the overlapping concentration c*. We created networks from sols of star-branched phantom bead-spring chains via an end-linking reaction between different chains through Brownian dynamics simulations upon varying the number of branching arms f from 1 to 8, and the conversion ratio φc from 0.6 to 0.95. For the resultant networks, the cycle rank ξ was consistent with the mean-field theory. The networks were uniaxially stretched with energy minimization until break to obtain modulus G, strain at break ϵb, stress at break σb, and work for fracture Wb. As reported earlier, ϵb data for various f and φc are located on a master curve if plotted against ξ. The other quantities also draw master curves as functions of ξ if normalized by the branch point density υbr. The master curves depend on c; as c increases, all the mechanical characteristics monotonically increase. If we plot σb/υbr and Wb/υbr against G/υbr, the data for various f and φc lie on master curves but depending on c. Consequently, the fracture characteristics are not solely described by the modulus.

DOI： 10.1039/d4sm00726c

Polyion Hydrogels of Polymeric and Nanofibrous Carboxymethyl Cellulose and Chitosan: Mechanical Characteristics and Potential Use in Environmental Remediation 査読有り国際誌 Open Access

Kawate T., Wang Y., Chan K., Shibata N., Doi Y., Masubuchi Y., Zinchenko A.

Gels 10 巻 ( 9 ) 2024年9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：Gels

Recently, cellulose and other biomass nanofibers (NFs) have been increasingly utilized in the design of sustainable materials for environmental, biomedical, and other applications. However, the past literature lacks a comparison of the macromolecular and nanofibrous states of biopolymers in various materials, and the advantages and limitations of using nanofibers (NF) instead of conventional polymers are poorly understood. To address this question, hydrogels based on interpolyelectrolyte complexes (IPECs) between carboxymethyl cellulose nanofibers (CMCNFs) and chitosan (CS) were prepared by ele+ctrostatic cross-linking and compared with the hydrogels of carboxymethyl cellulose (CMC) and CS biopolymers. The presence of the rigid CMCNF altered the mechanism of the IPEC assembly and drastically affected the structure of IPEC hydrogels. The swelling ratios of CMCNF-CS hydrogels of ca. 40% were notably lower than the ca. 100–300% swelling of CMC-CS hydrogels. The rheological measurements revealed a higher storage modulus ((Formula presented.)) of the CMCNF-CS hydrogel, reaching 13.3 kPa compared to only 3.5 kPa measured for the CMC-CS hydrogel. Further comparison of the adsorption characteristics of the CMCNF-CS and CMC-CS hydrogels toward Cu2+, Cd2+, and Hg2+ ions showed the slightly higher adsorption capacity of CMC-CS for Cu2+ but similar adsorption capacities for Cd2+ and Hg2+. The adsorption kinetics obeyed the pseudo-second-order adsorption model in both cases. Overall, while the replacement of CMC with CMCNF in hydrogel does not significantly affect the performance of such systems as adsorbents, CMCNF imparts IPEC hydrogel with higher stiffness and a frequency-independent loss ((Formula presented.)) modulus and suppresses the hydrogel swelling, so can be beneficial in practical applications that require stable performance under various dynamic conditions.

DOI： 10.3390/gels10090604

Coarse-grained molecular dynamics simulation of oxidative aging of polymers -effect of free radical diffusivity - 招待有り査読有り国際誌

Ishida, T; Doi, Y; Uneyama, T; Masubuchi, Y

POLYMER JOURNAL 2024年8月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Polymer Journal

Recently, we developed an oxidative aging simulation technique that explicitly considers the transport of radicals by combining oxidation kinetics with coarse-grained molecular dynamics [1]. The current study explores the role of the free radical diffusivity of oxidative aging in polymers, with a focus on its effects on the heterogeneity of spatiotemporal structures and reaction kinetics, through coarse-grained simulations. By examining two distinct systems, including a heterosystem with a high reaction rate and a quasi-homosystem with a low reaction rate, we investigated how the diffusivity of free radicals influences the oxidative aging process. We examined three different diffusivity levels of radicals. For the slowest case, the radical diffusivity is slightly faster than that of the single polymer segment, whereas for the fastest case, the radical diffuses infinitely faster than the polymers. The aging simulations revealed that the variations in free radical diffusivity quantitatively change the reaction kinetics and spatiotemporal structures without qualitatively altering the overall aging behavior. Specifically, in a heterosystem, lower radical diffusivity slows the oxidation kinetics by increasing fluctuations in the local conversion ratios. In contrast, in a quasi-homosystem, reduced radical diffusivity slightly amplifies the heterogeneity of structures in the early aging stages; however, in a high-conversion region, the aged state becomes homogeneous regardless of the degree of radical diffusivity.

DOI： 10.1038/s41428-024-00942-5

その他リンク： https://www.nature.com/articles/s41428-024-00942-5

Primitive Chain Network Simulations for Double Peaks in Shear Stress under Fast Flows of Bidisperse Entangled Polymers 招待有り査読有り国際誌 Open Access

Masubuchi Y.

Polymers 16 巻 ( 11 ) 頁： 1455-1 - 1455-10 2024年5月

担当区分：筆頭著者,　最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Polymers

A few experiments have reported that the time development of shear stress under fast-startup shear deformations exhibits double peaks before reaching a steady state for bimodal blends of entangled linear polymers under specific conditions. To understand this phenomenon, multi-chain slip-link simulations, based on the primitive chain network model, were conducted on the literature data of a bimodal polystyrene solution. Owing to reasonable agreement between their data and our simulation results, the stress was decomposed into contributions from long- and short-chain components and decoupled into segment number, stretch, and orientation. The analysis revealed that the first and second peaks correspond to the short-chain orientation and the long-chain stretch, respectively. The results also implied that the peak positions are not affected by the mixing of short and long chains, although the intensity of the second peak depends on mixing conditions in a complicated manner.

DOI： 10.3390/polym16111455

Dissipative Particle Dynamics Simulation Plus Slip-Springs for Entangled Polymers with Various Slip-Spring Densities 査読有り国際共著国際誌

Masubuchi, Y; Guo, HX; Wang, F; Khomami, B; Boudaghi-Khajehnobar, M; Doi, Y; Ishida, T; Uneyama, T

MACROMOLECULES 57 巻 ( 10 ) 頁： 4867 - 4877 2024年5月

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

Slip-spring models are valuable tools for simulating entangled polymers, bridging the gap between bead-spring models with excluded volume and network models with presumed reptation motion. This study focuses on the DPD-SS (Dissipative Particle Dynamics-Slip-Spring) model, which introduces slip springs into the standard DPD polymer model with soft-core interactions. By systematically adjusting the activity of slip springs, the density of slip springs within the system is varied. Simulation results demonstrate the compatibility of models with different slip-spring densities in terms of diffusion and linear relaxation modulus when the average number of slip springs per chain is the same. The conversion between DPD-SS models concerning length and time is achieved through Rouse scaling, which utilizes the average number of DPD beads between consecutive anchoring points of slip springs. Additionally, the modulus conversion is accomplished through the plateau modulus that takes account of fluctuations around entanglement. Notably, diffusion and relaxation modulus from the DPD-SS model align with those reported for standard Kremer-Grest and DPD models featuring strong repulsive interactions.

DOI： 10.1021/acs.macromol.4c00280

Effect of Surface Treatment for Iron Particles with Excessive Amounts of Silane Coupling Agent on Rheological Properties of Magnetorheological Fluids 招待有り査読有り国際誌

Yamawaki Y., Ishida T., Doi Y., Uneyama T., Masubuchi Y.

Nihon Reoroji Gakkaishi 52 巻 ( 2 ) 頁： 99 - 105 2024年4月

担当区分：最終著者,　責任著者記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Nihon Reoroji Gakkaishi

We investigated the effect of surface treatment for iron particles in the magnetorheological fluids (MRFs) on rheological properties. Silane coupling treatment with an excess amount of dodecyltrimethoxysilane (DTMS) was conducted for iron particles. MRFs were prepared by dispersing iron particles with and without the silane coupling treatment. MRFs with iron particles washed with n-hexane after the silane coupling treatment was also prepared. The rheological properties of MRFs were measured in the presence and absence of a magnetic field. Without a magnetic field, MRFs with the silanecoupled particles exhibited higher stress than the untreated particles. Under a magnetic field, MRFs with the silane-coupled particles showed lower stress than the untreated analogue. These results imply that the silane coupling treatment enhances the aggregation of particles without a magnetic field but suppresses the cluster formation under the magnetic field. MRFs with the washed iron particles exhibited almost the same rheological properties as that with the untreated particles. Thus we suggest that DTMS is mainly physically absorbed on the surface of iron particles, without forming chemical bonds.

DOI： 10.1678/rheology.52.99

Anisotropy of Shear Relaxation in Primitive Chain Network Simulations for Entangled Polymers Confined between Flat Walls 招待有り査読有り国際誌

Masubuchi Y.

Nihon Reoroji Gakkaishi 52 巻 ( 2 ) 頁： 77 - 82 2024年4月

担当区分：筆頭著者,　最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nihon Reoroji Gakkaishi

Anisotropic shear relaxation is an interesting but rarely discussed issue in polymer dynamics under confinement. According to the earlier study of bead spring simulations for an unentangled polymer melt confined between two flat plates, the shear relaxation modulus taken perpendicular to the interface is accelerated by decreasing the distance between plates, whereas the parallel component is unchanged [Abberton et al., Macromolecules, 48, 7631, 2015]. This study observed similar anisotropic shear relaxation for entangled polymer melts under confinement in multi-chain slip-link simulations (primitive chain network simulations) for shear relaxation moduli obtained by the Green-Kubo formula. The analysis demonstrated that the accelerated relaxation in the perpendicular component reflects the Rouse-type constraint release dynamics, for which the coarsening is upper-limited by the geometry. This result suggests a novel mechanism for anisotropic shear relaxation different from the modified chain statistics under confinement considered for unentangled systems unless the obtained relaxation moduli reflect artifacts from the use of the Green-Kubo formula under confinement.

DOI： 10.1678/RHEOLOGY.52.77

Phantom Chain Simulations for Fracture of End-linking Networks 査読有り国際誌 Open Access

Yuichi Masubuchi

Polymer 297 巻頁： 126880-1 - 126880-8 2024年3月

Phantom chain simulations for the effect of stoichiometry on the fracture of star-polymer networks 査読有り国際誌

Yuichi Masubuchi

Nihon Reoroji Gakkaishi 52 巻 ( 1 ) 頁： 21 - 26 2024年2月

Phantom chain simulations for fracture of polymer networks created from star polymer mixtures of different functionalities 査読有り国際誌

Masubuchi Y.

Polymer Journal 56 巻頁： 163 - 171 2023年12月

担当区分：筆頭著者,　最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Polymer Journal

Fujiyabu et al. [1] experimentally reported that mixing of 3-arm star prepolymers into 4-arm analogs improves the toughness of the resultant polymer networks compared to that of the base network composed of only 4-arm star polymers. The present study investigated the mechanism of this phenomenon based on phantom chain simulations for polymer networks consisting of mixtures of star branch prepolymers with equal arm length and different arm numbers, (f1,f2)=(3, 4) , (3, 6) and (3, 8) , for various f1= 3 prepolymer fractions φ3 . These networks were created via end-linking reactions between prepolymers traced by a Brownian dynamics scheme, and the network structure was stored at different conversion ratios φc , ranging from 0.6 to 0.9. The cycle rank of the gelated networks ξ is entirely consistent with that given by mean-field theory, demonstrating that the examined network structure is statistically valid. The networks were stretched with energy minimization until the break, and fracture characteristics including strain at break εb , stress at break σb , work for fracture Wb , and the ratio of broken strands φbb , were obtained. Plots of εb , σb/ φbb , and Wb/ φbb versus ξ roughly follow the master curves reported for the base networks without mixing, implying that the change of fracture properties by the mixing of f1= 3 mainly corresponds to a decrease in ξ . The mixing slightly suppresses σb/ φbb and Wb/ φbb for large f2 cases compared to the base networks because of a biased breakage at the network strands without extenders, which are prepolymers with only two reacted arms. The analysis also revealed a new master curve for the ξ -dependence of the molecular weight of broken strands.

DOI： 10.1038/s41428-023-00862-w

Modeling for Heterogeneous Oxidative Aging of Polymers Using Coarse-Grained Molecular Dynamics 査読有り国際誌 Open Access

Ishida T., Doi Y., Uneyama T., Masubuchi Y.

Macromolecules 56 巻 ( 21 ) 頁： 8474 - 8483 2023年11月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Macromolecules

This study presents a coarse-grained molecular dynamics simulation model to investigate the process of oxidative aging in polymers. The chemical aging effect is attributed to the autoxidation mechanism, which is initiated by radicals, leading to the chain scission and cross-linking of polymer chains. In this study, we integrate a thermal oxidation kinetic model in the oxygen excess regime into the Kremer-Grest model, thereby enabling a reactive coarse-grained molecular dynamics simulation to capture the process of oxidative degradation. Our simulation reveals that when the time scale of the characteristic reaction step of oxidative degradation is shorter than the longest relaxation time of polymer chains, the scission sites exhibit spatial heterogeneity. This innovative simulation model possesses the potential to enhance our comprehension of polymer aging phenomena, thus making noteworthy contributions to the realm of polymer science and degradation chemistry.

DOI： 10.1021/acs.macromol.3c01708

Effects of attractive inter-particle interaction on cross-transport coefficient between mass and heat in binary fluids 査読有り国際誌 Open Access

Oishi, T; Doi, Y; Masubuchi, Y; Uneyama, T

MOLECULAR SIMULATION 2023年10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：Molecular Simulation

In some binary fluids, mass transport is observed under a temperature gradient. This phenomenon is called the Soret effect. In this study, we discuss the influence of inter-particle interaction. We considered equimolar binary Lennard–Jones fluids with a mass contrast, whereas the interaction was common for all the particle pairs with various cut-off lengths. We performed molecular dynamics simulations of such fluids under equilibrium to obtain the cross-transport coefficients (Formula presented.) between the fluxes of mass and heat. The simulation revealed that this quantity strongly depends on the cut-off length. Further, we decomposed the heat flux into kinetic and potential contributions and calculated the cross-correlations between decomposed fluxes and the mass flux. The result indicates that the potential contribution dominates (Formula presented.), implying that the Soret coefficient is altered by the inter-particle interaction.

DOI： 10.1080/08927022.2023.2268730

A Multi-Chain Slip-Spring Model without the Slip-Spring Degeneracy 査読有り国際誌 Open Access

Masubuchi, Y; Doi, Y; Ishida, T; Uneyama, T

NIHON REOROJI GAKKAISHI 51 巻 ( 4 ) 頁： 211 - 217 2023年10月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nihon Reoroji Gakkaishi

In the multi-chain slip-spring, the dynamics of Rouse chains connected by virtual springs called slip-springs that hop along the chain are considered. Although this approach has been proven to reproduce entangled polymer dynamics efficiently, the settings of the artificially introduced slip-springs should be carefully examined. In this study, we discussed the effect of the slip-spring degeneracy by limiting the number of anchored slip-springs on each Rouse bead to zero and one. According to the altered slip-spring statistics, we derived the compensation potential to eliminate the artifact of slip-springs on the chain statistics. With this potential, we performed numerical simulations. The results demonstrated that although we reasonably retain the Gaussian chain statistics, the dynamics deviate from the established entangled polymer dynamics because of the significant slow-down in the chain motion induced by the correlation between different slip-springs. The observed deceleration can be explained by the fact that the movement of slip-springs can be cast into an asymmetric exclusion process.

DOI： 10.1678/rheology.51.211

Extension of moving particle simulation by introducing rotational degrees of freedom for dilute fiber suspensions 査読有り国際誌

Enomoto K., Ishida T., Doi Y., Uneyama T., Masubuchi Y.

International Journal for Numerical Methods in Fluids 96 巻頁： 125 - 137 2023年9月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：International Journal for Numerical Methods in Fluids

We develop a novel Moving Particle Simulation (MPS) method to reproduce the motion of fibers floating in sheared liquids accurately. In conventional MPS schemes, if a fiber suspended in a liquid is represented by a one-dimensional array of MPS particles, it is entirely aligned to the flow direction due to the lack of shear stress difference between fiber–liquid interfaces. To address this problem, we employ the micropolar fluid model to introduce rotational degrees of freedom into the MPS particles. The translational motion of liquid and solid particles and the rotation of solid particles are calculated with the explicit MPS algorithm. The fiber is modeled as an array of micropolar fluid particles bonded with stretching, bending and torsional potentials. The motion of a single rigid fiber is simulated in a three-dimensional shear flow generated between two moving solid walls. We show that the proposed method is capable of reproducing the fiber motion predicted by Jeffery's theory which is different from the conventional MPS simulations.

DOI： 10.1002/fld.5235

Phantom-Chain Simulations for the Effect of Node Functionality on the Fracture of Star-Polymer Networks 査読有り国際誌 Open Access

Masubuchi, Y; Doi, Y; Ishida, T; Sakumichi, N; Sakai, T; Mayumi, K; Satoh, K; Uneyama, T

MACROMOLECULES 56 巻 ( 23 ) 頁： 9359 - 9367 2023年9月

Preparation and characterization of two-dimensional sheet-shaped poly(methyl methacrylate) synthesized via γ-ray polymerization in nanoclay template 招待有り査読有り国際誌 Open Access

Doi Y., Hara M., Seki T., Takano A., Ishida T., Uneyama T., Masubuchi Y.

Polymer Journal 55 巻 ( 9 ) 頁： 957 - 965 2023年5月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Polymer Journal

Two-dimensional sheet-shaped poly(methyl methacrylate) (2d-PMMA) with crosslinking only in the two-dimensional direction was synthesized via planar polymerization of MMA monomer in montmorillonite (MMT) nanolayers by using γ-ray irradiation, and the samples obtained were characterized. Size-exclusion chromatography with a multi-angle light scattering (SEC-MALS) measurements of the obtained sample showed bimodal peaks: a main peak with a longer elution time and an apparent molecular weight M w,app and radius of gyration R g in tetrahydrofuran (THF) similar to those for linear PMMA samples, and a subpeak with a shorter elution time and M w,app and R g evidently lower than those for the linear PMMA samples. This result indicated that polymers with moderate branching and crosslinking were contained in the subpeak. Atomic force microscopy (AFM) observation of the sample showed the presence of sheet-shaped molecules with a height of ca. 0.6 nm, corresponding to the thickness of one MMA monomer, and a width of several to several tens of nanometers, showing a broad distribution in molecular width. The subpeak portion was isolated via SEC fractionation, and its AFM observation showed thin circular disk-shaped molecules with relatively uniform size (i.e., a width of several tens of nanometers). However, in these molecules, two types of molecular heights (i.e., 0.6 and 1.2 nm) were identified. This result indicated that MMA monomers were filled as two layers within one MMT interlayer, and the polymerization reaction proceeded in that state. The similarity in the molecular size of 2d-PMMA observed via AFM and SEC-MALS was confirmed. These results demonstrated that the desired sheet-shaped polymers were obtained through the above synthesis and fractionation process.

DOI： 10.1038/s41428-023-00795-4

その他リンク： https://www.nature.com/articles/s41428-023-00795-4

Undershoots in shear startup of entangled linear polymer blends 招待有り査読有り国際共著国際誌 Open Access

Parisi Daniele, Vereroudakis Emmanouil, Masubuchi Yuichi, Ianniruberto Giovanni, Marrucci Giuseppe, Vlassopoulos Dimitris

JOURNAL OF NON-NEWTONIAN FLUID MECHANICS 315 巻 2023年5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：Journal of Non-Newtonian Fluid Mechanics

We revisit the transient response of entangled polymers in shear startup. Evidence from state-of-the-art experiments, modeling and simulations suggests the presence in fast flows of a weak (albeit unambiguous) undershoot, following the overshoot, i.e., while approaching the steady state. Recent sliplink simulations confirmed that the undershoot is not due to slip at the wall, and hence it is intrinsic to polymer rheology. Here, we further examine some features of the undershoot by blending two entangled homopolymers at different compositions. Since blending affects the distribution of relaxation times, it is here shown to also affect the undershoot, probably by broadening the tumbling-time distribution. Indeed, by appropriately modifying our tube-based model, that invokes tumbling to account for the undershoot, and (in parallel) by using simulations, we show how the undershoot depends on the blend composition. We map the experimental results into a diagram of terminal relaxation time versus composition, which identifies regimes where the undershoot is present. Blending is therefore proposed as a molecular mechanism to tailor the shear stress growth function signal, particularly the undershoot.

DOI： 10.1016/j.jnnfm.2023.105028

Primitive chain network simulations of the nonlinear rheology of polystyrene melts: Friction reduction and fluctuation-dissipation theorem 招待有り査読有り国際共著国際誌 Open Access

Masubuchi Yuichi, Ianniruberto Giovanni, Wagner Manfred, Marrucci Giuseppe

JOURNAL OF NON-NEWTONIAN FLUID MECHANICS 315 巻 2023年5月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Non-Newtonian Fluid Mechanics

Description of the elongational rheology of concentrated polymers appears to require that in fast flows the friction coefficient decreases with respect to its equilibrium value. However, the proposed models typically maintain the validity of the fluctuation-dissipation theorem (FDT) out of equilibrium. On the other hand, FDT is routed in local equilibrium, the latter being clearly violated by the flow-induced monomer coalignment that induces friction change. A recent analysis by Watanabe et al. [Macromolecules, 54, 3700 (2021)] of unentangled polystyrene (PS) melts, based on a nonlinear extension of the Rouse model, indicates that FDT is indeed violated in fast flows. According to their analysis, the Brownian force intensity remains almost independent of the flow rate, even though the friction coefficient drastically decreases. A different violation of FDT is shown by previous nonequilibrium molecular dynamics simulations of PS oligomers [Ianniruberto et al., Macromolecules, 45, 8058 (2012)] where the diffusion coefficient grows more than the inverse friction coefficient. In this paper, Brownian simulations using a multi-chain sliplink model (the so-called primitive chain network model) are reported for two monodisperse entangled PS melts, for which nonlinear shear and elongational data were published. Two different friction reduction models are examined, and the effect of switching FDT on and off is tested. Results demonstrate that, irrespective of FDT, both friction models can reasonably well reproduce the behavior shown by the data. This result lends support to models that retain FDT since its violation appears not to significantly affect predictions of nonlinear rheology.

DOI： 10.1016/j.jnnfm.2023.105019

Increase in rod diffusivity emerges even in Markovian nature 査読有り国際共著国際誌 Open Access

Nakai Fumiaki, Kroger Martin, Ishida Takato, Uneyama Takashi, Doi Yuya, Masubuchi Yuichi

PHYSICAL REVIEW E 107 巻 ( 4 ) 2023年4月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physical Review E

Rod-shaped particles embedded in certain matrices have been reported to exhibit an increase in their center of mass diffusivity upon increasing the matrix density. This increase has been considered to be caused by a kinetic constraint in analogy with tube models. We investigate a mobile rodlike particle in a sea of immobile point obstacles using a kinetic Monte Carlo scheme equipped with a Markovian process, that generates gaslike collision statistics, so that such kinetic constraints do essentially not exist. Even in such a system, provided the particle's aspect ratio exceeds a threshold value of about 24, the unusual increase in the rod diffusivity emerges. This result implies that the kinetic constraint is not a necessary condition for the increase in the diffusivity.

DOI： 10.1103/PhysRevE.107.044604

Phantom Chain Simulations for the Fracture of Energy-Minimized Tetra- and Tri-Branched Networks 査読有り国際誌

Masubuchi Yuichi, Doi Yuya, Ishida Takato, Sakumichi Naoyuki, Sakai Takamasa, Mayumi Koichi, Uneyama Takashi

MACROMOLECULES 2023年2月

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

Effects of branch functionality on mechanical properties of polymer networks are yet to be fully elucidated, although multi-functional approaches have been mainly attempted. For instance, Fujiyabu et al. [Sci. Adv. 2022, 8, abk0010] recently reported that polymer networks made from tri-branch prepolymers exhibit superior mechanical properties to tetra-branch analogues. Although they attribute the difference to stretch-induced crystallization observed in tri-branch poly (ethylene glycol) networks, the mechanism still needs to be clarified. In this study, we performed coarse-grained molecular simulations to extract the effect of branch functionality. The prepolymers were replaced by bead-spring phantom chains, and gelation was simulated by a Brownian dynamics scheme. We subjected the resultant networks to energy minimization and uniaxial stretch by introducing breakage for elongated segments. In the stress-strain relation thus obtained, stress and strain at the break were larger for tri-branch networks than that for tetra-branch analogues, consistent with the experiment. The superiority of tri-branch networks is observed in a wide range of the conversion ratio in gelation, molecular weights of prepolymers, and polymer concentrations. The result implies that the mechanical superiority of tri-branch networks to tetra-branch ones is due to a fundamental structural difference generated during gelation.

DOI： 10.1021/acs.macromol.3c00047

Tube Survival Fraction in Primitive Chain Network Simulations 査読有り国際誌 Open Access

Masubuchi Yuichi

Nihon Reoroji Gakkaishi 51 巻 ( 1 ) 頁： 19 - 24 2023年2月

担当区分：筆頭著者,　最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：The Society of Rheology, Japan

In the framework of the tube model, the survival fraction of dilated tube, φʹ(t), is essential since the relaxation of the entire system is described according to this quantity. However, a method to define it in multi-chain simulations has yet to be considered. In this study, primitive chain network simulations were performed, and a few structural quantities were discussed as possible candidates for use as φʹ(t). Before analysis, the simulation was evaluated against literature data for linear polyisoprene melts, and quantitative agreement was obtained for viscoelastic and dielectric relaxations. Afterward, the end-to-end relaxation function was compared to survival probability of the slip link φs(t) and the ratio of monomers between the most distant surviving slip link pair to the total number of monomers ns(t)/nt. The result implies that ns(t)/nt is comparable to φʹ(t). Comparison to atomistic molecular dynamics (MD) simulations for polyethylene showed similar results, implying that φʹ(t) can be obtained even in MD simulations if the surviving entanglement points can be specified.

DOI： 10.1678/rheology.51.19

Elongational viscosity of poly(propylene carbonate) melts: tube-based modelling and primitive chain network simulations 査読有り国際共著国際誌 Open Access

Wagner Manfred H., Narimissa Esmaeil, Masubuchi Yuichi

RHEOLOGICA ACTA 62 巻 ( 1 ) 頁： 1 - 14 2023年1月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Rheologica Acta

In fast elongational flows, linear polymer melts exhibit a monotonic decrease of the viscosity with increasing strain rate, even beyond the contraction rate of the polymer defined by the Rouse time. We consider two possible explanations of this phenomenon: (a) the reduction of monomeric friction and (b) the reduction of the tube diameter with increasing deformation leading to an Enhanced Relaxation of Stretch (ERS) on smaller length scales. (Masubuchi et al. (2022) reported Primitive Chain Network (PCN) simulations using an empirical friction reduction model depending on segmental orientation and could reproduce the elongational viscosity data of three poly(propylene carbonate) melts and a polystyrene melt. Here, we show that the mesoscopic tube-based ESR model (Wagner and Narimissa 2021) provides quantitative agreement with the same data set based exclusively on the linear-viscoelastic characterization and the Rouse time. From the ERS model, a parameter-free universal relation of monomeric friction reduction as a function of segmental stretch can be derived. PCN simulations using this friction reduction relation are shown to reproduce quantitatively the experimental data even without any fitting parameter. The comparison with results of the earlier PCN simulation results with friction depending on segmental orientation demonstrates that the two friction relations examined work equally well which implies that the physical mechanisms of friction reduction are still open for discussion.

DOI： 10.1007/s00397-022-01373-w

Fluctuating diffusivity emerges even in binary gas mixtures 査読有り国際誌 Open Access

Nakai F., Masubuchi Y., Doi Y., Ishida T., Uneyama T.

Physical Review E 107 巻 ( 1 ) 2023年1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：Physical Review E

Diffusivity in some soft matter and biological systems changes with time, called the fluctuating diffusivity. In this work, we propose a novel origin for fluctuating diffusivity based on stochastic simulations of binary gas mixtures. In this system, the fraction of one component is significantly small, and the mass of the minor component molecule is different from that of the major component. The minor component exhibits fluctuating diffusivity when its mass is sufficiently smaller than that of the major component. We elucidate that this fluctuating diffusivity is caused by the time scale separation between the relaxation of the velocity direction and the speed of the minor component molecule.

DOI： 10.1103/PhysRevE.107.014605

世界情勢とInternational Committee on Rheology 国際誌

増渕雄一

日本レオロジー学会誌 50 巻 ( 5 ) 頁： 391 - 392 2022年12月

CNT Gels Formed by a Triptycene Analogue Enabling Coexistence of CNT-gelator and Intergelator Interactions 査読有り国際誌

Ushiroguchi R., Suizu R., Matsunaga Y., Omachi H., Doi Y., Masubuchi Y., Bandow S., Awaga K.

Chemistry Letters 51 巻 ( 11 ) 頁： 1070 - 1073 2022年11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：Chemistry Letters

We report carbon nanotube (CNT) gels, formed by mechanically mixing CNTs, organic solvents, and a small molecule, Trip-Phz, that have a strong affinity for fullerene materials. There is a clear threshold value in the amount of Trip-Phz needed for the transition from soft to hard gels.

DOI： 10.1246/cl.220319

Viscoelastic properties of comb-shaped ring polystyrenes 招待有り査読有り国際誌 Open Access

Doi Y., Kitamura J., Uneyama T., Masubuchi Y., Takano A., Takahashi Y., Matsushita Y.

Polymer Journal 54 巻 ( 11 ) 頁： 1267 - 1277 2022年11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：Polymer Journal

In this study, we examined the viscoelastic properties of a series of comb-shaped ring (RC) polystyrene samples with different branch chain lengths, i.e., the molecular weights of the ring backbone Mbb (≃ 4Me where Me is the entanglement molecular weight) and branch chains Mbr (≃ Me, 2Me, and 4Me). Even for the RC sample with the shortest branch chains, a plateau region was observed for the dynamic modulus G*(ω) in the middle angular frequency ω region, suggesting that intermolecular branch chain entanglement occurred. In the ω region between the plateau and terminal regions, G*(ω) was observed with a weaker ω dependence than the terminal relaxation. This behavior was more pronounced for RC samples with shorter branch chains and for the corresponding linear comb (LC) samples than for the RC ones. The molecular weight dependence of the zero-shear viscosity η0 and the steady-state recoverable compliance Jeo of the RC and LC samples was evaluated, and the effects of different backbone molecular structures (i.e., ring or linear) on the terminal relaxation behavior was discussed. Moreover, the G*(ω) data were analyzed with two models: the comb-Rouse model, in which the structures of the RC/LC molecules are taken into account by graph theory, and the Milner-McLeish model for entangled star-shaped polymers. The former model qualitatively described the terminal relaxation behavior of G*(ω) at low ω but failed to reproduce the plateau in the middle ω range. Conversely, the latter model described the entanglement plateau in the middle ω range, but the difference in the terminal relaxation regime for the RC/LC samples seen in the data and the comb-Rouse model disappeared.

DOI： 10.1038/s41428-022-00686-0

Stress Tensor of Single Rigid Dumbbell by Virtual Work Method 査読有り国際誌 Open Access

Uneyama Takashi, Oishi Tatsuma, Ishida Takato, Doi Yuya, Masubuchi Yuichi

Nihon Reoroji Gakkaishi 50 巻 ( 4 ) 頁： 313 - 322 2022年9月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：The Society of Rheology, Japan

We derive the stress tensor of a rigid dumbbell by using the virtual work method. In the virtual work method, we virtually apply a small deformation to the system, and relate the change of the energy to the work done by the stress tensor. A rigid dumbbell consists of two particles connected by a rigid bond of which length is constant (the rigid constraint). The energy of the rigid dumbbell consists only on the kinetic energy. Also, only the deformations which do not violate the rigid constraint are allowed. Thus we need the dynamic equations which are consistent with the rigid constraint to apply the virtual deformation. We rewrite the dynamic equations for the underdamped SLLOD-type dynamic equations into the forms which are consistent with the rigid constraint. Then we apply the virtual deformation to a rigid dumbbell based on the obtained dynamic equations. We derive the stress tensor for the rigid dumbbell model from the change of the kinetic energy. Finally, we take the overdamped limit and derive the stress tensor and the dynamic equation for the overdamped rigid dumbbell. We show that the Green-Kubo type linear response formula can be reproduced by combining the stress tensor and the dynamic equation at the overdamped limit.

DOI： 10.1678/rheology.50.313

Primitive Chain Network Simulations for Shear Rheology of Poly(propylene carbonate) Melts 査読有り国際誌 Open Access

Masubuchi Yuichi, Yang Lixin, Uneyama Takashi, Doi Yuya

Nihon Reoroji Gakkaishi 50 巻 ( 4 ) 頁： 305 - 312 2022年9月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：The Society of Rheology, Japan

Although chemistry dependence in the non-linear rheology of polymers has been rather established for uniaxial elongations, it has not been frequently discussed for fast shear. In this study, to see the effect of orientation-dependent monomeric friction on the shear rheology, we conducted primitive chain network simulations for a few poly(propylene carbonate) melts, for which we have determined the friction model from the uniaxial data recently [Yang et al., Nihon Reoroji Gakkaishi, 50, 127–135 (2022)]. The simulation qualitatively reproduced typical non-linear behaviors, such as shear thinning and stress overshoot, under fast shears. The agreement with experimental data became better when the friction was varied according to the segment orientation. In particular, the shear rate dependence of the peak position for the stress overshoot (i.e., the peak stress and the strain at the peak) was better reproduced. This result implies that chemistry-dependent friction may probably be discussed from the stress overshoot under high shear.

DOI： 10.1678/rheology.50.305

Brownian simulations for tetra-gel-type phantom networks composed of prepolymers with bidisperse arm length 招待有り査読有り国際誌

Masubuchi Yuichi, Yamazaki Ryohei, Doi Yuya, Uneyama Takashi, Sakumichi Naoyuki, Sakai Takamasa

SOFT MATTER 18 巻 ( 25 ) 頁： 4715 - 4724 2022年6月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Soft Matter

We studied the effect of arm length contrast of prepolymers on the mechanical properties of tetra-branched networks via Brownian dynamics simulations. We employed a bead-spring model without the excluded volume interactions, and we did not consider the solvent explicitly. Each examined 4-arm star branch prepolymer has uneven arm lengths to attain two-against-two (2a2) or one-against-three (1a3) configurations. The arm length contrast was varied from 38-2 to 20-20 for 2a2, and from 5-25 to 65-5 for 1a3, with the fixed total bead number of 81, including the single bead located at the branch point for prepolymers. We distributed 400 molecules in the simulation box with periodic boundary conditions, and the bead number density was fixed at 4. We created polymer networks by cross-end-coupling of equilibrated tetra-branched prepolymers. To mimic the experiments of tetra gels, we discriminated the molecules into two types and allowed the reaction only between different types of molecules at their end beads. The final conversion ratio was more than 99%, at which unreacted dangling ends are negligible. We found that the fraction of double linkage, in which two of the four arms connect a pair of branch points, increases from 3% to 15% by increasing the arm length contrast. We stretched the resultant tetra-type networks to obtain the ratio of mechanically effective strands. We found that the ratio is 96% for the monodisperse system, decreasing to 90% for high arm length contrast. We introduced bond scission according to the bond stretching to observe the network fracture under sufficiently slow elongation. The fracture behavior was not correlated with the fraction of double linkage because the scission occurs at single linkages.

DOI： 10.1039/d2sm00488g

Effects of Slip-Spring Parameters and Rouse Bead Density on Polymer Dynamics in Multichain Slip-Spring Simulations 招待有り査読有り国際誌

Masubuchi Yuichi, Doi Yuya, Uneyama Takashi

JOURNAL OF PHYSICAL CHEMISTRY B 126 巻 ( 15 ) 頁： 2930 - 2941 2022年4月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Physical Chemistry B

The multichain slip-spring (MCSS) model is one of the coarse-grained models of polymers developed in the niche between bead-spring models and tube type descriptions. In this model, polymers are represented by Rouse chains connected by virtual springs that temporally connect the chains, hop along the chain, and are constructed and annihilated at the chain ends. Earlier studies have shown that MCSS simulations can nicely reproduce entangled and unentangled polymer dynamics. However, the model parameters have been chosen arbitrarily, and their effects have not been reported. In this study, for the first time, we systematically investigated the effects of model parameters: fugacity of virtual springs, its intensity, and the Rouse bead density. We validated the employed simulation code by confirming that the statistics of the system follow the theoretical setup. Namely, the virtual spring density is correctly controlled, and polymer chains exhibit ideal chain statistics irrespective of the chosen parameter values. For diffusion and linear viscoelasticity, simulation results obtained for different parameters can be superposed with each other by conversion factors for the bead number per chain and units of length, time, and modulus. These conversion factors follow scaling laws concerning the number of Rouse segments between two consecutive anchoring points of virtual springs along the polymer chain. Besides, diffusion and viscoelasticity excellently agree with literature data for the standard bead-spring simulation. These results imply that the coarse-graining level for the MCSS model can be arbitrarily chosen and controlled by model parameters.

DOI： 10.1021/acs.jpcb.2c00697

Analysis of Elongational Viscosity of Entangled Poly (Propylene Carbonate) Melts by Primitive Chain Network Simulations 招待有り査読有り国際誌 Open Access

Masubuchi Y., Yang L., Uneyama T., Doi Y.

Polymers 14 巻 ( 4 ) 頁： 741-1 - 741-15 2022年2月

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

It has been established that the elongational rheology of polymers depends on their chemistry. However, the analysis of experimental data has been reported for only a few polymers. In this study, we analyzed the elongational viscosity of poly (propylene carbonate) (PPC) melts in terms of monomeric friction via primitive chain network simulations. By incorporating a small polydispersity of materials, the linear viscoelastic response was semi-quantitatively reproduced. Owing to this agreement, we determined units of time and modulus to carry out elongational simulations. The simulation with constant monomeric friction overestimated elongational viscosity, whereas it nicely captured the experimental data if friction decreased with increasing segment orientation. To see the effect of chemistry, we also conducted the simulation for a polystyrene (PS) melt, which has a similar entanglement number per chain and a polydispersity index. The results imply that PPC and PS behave similarly in terms of the reduction of friction under fast deformations.

DOI： 10.3390/polym14040741

Nonlinear Shear and Elongational Rheology of Poly(propylene carbonate) 査読有り国際誌 Open Access

Yang L., Uneyama T., Masubuchi Y., Doi Y.

Nihon Reoroji Gakkaishi 50 巻 ( 1 ) 頁： 127 - 135 2022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：Nihon Reoroji Gakkaishi

Nonlinear shear and elongational rheology of entangled poly(propylene carbonate) (PPC) melts having different molecular weights with relatively narrow molecular weight distribution are examined. In shear measurements, the PPCs exhibit a typical shear thinning behavior with stress overshoot at high shear rates. In the shear rate dependence of the steadystate viscosity, the PPCs do not violate the empirical Cox-Merz rule, which is known to be valid for many other entangled polymer melts. In uniaxial elongational measurements, the viscosity growth functions of the PPCs show a weak deviation from the linear viscoelastic (LVE) envelope to the higher side at the high Weissenberg number Wid (= ͘ετd, where ͘ε is the elongation rate and τd is the characteristic disengagement time). The steady-state viscosity of the PPCs shows an elongational thinning as a function of ͘ε −0.5 within an error. These results are similar to some other polymer melts such as polystyrene (PS). In addition, the normalized elongational viscosity growth functions of PPC and PS with a similar entanglement number Z, are compared. The PPC exhibits a similar viscosity growth curve to the PS at the same Wid. This result suggests that the degree of the monomeric friction reduction originated from the stretch/orientation of PPC under fast elongational flow might occur at the same level as PS.

DOI： 10.1678/rheology.50.127

Rheological properties of linear and short-chain branched polyethylene with nearly monodispersed molecular weight distribution 査読有り国際誌

Kida T., Doi Y., Tanaka R., Uneyama T., Shiono T., Masubuchi Y.

Rheologica Acta 60 巻 ( 9 ) 頁： 511 - 519 2021年7月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Rheologica Acta

We synthesized model polyethylene (PE) samples with nearly monodispersed molecular weight distribution and different fractions of short-chain branches to investigate the influences of the branch structure on the rheological properties. The activation energy of the flow process showed linear relations with the weight fractions of comonomer and the short-chain branch. These results suggest that the friction of the chain motion is dominated by the amount of the short-chain branch. The zero-shear viscosity showed a power law to Mw with an exponent of about 3.3 for all linear and branched PEs. The branched PEs showed large entanglement molecular weights compared with the linear PEs because the introduction of the short-chain branches results in the increase of the average molecular weight per backbone unit. Moreover, the introduction of the short-chain branches has no influence on the strain-hardening under an extensional elongation process, indicating that the short-chain branches only affect the friction.

DOI： 10.1007/s00397-021-01286-0

その他リンク： https://link.springer.com/article/10.1007/s00397-021-01286-0/fulltext.html

Wall slip in primitive chain network simulations of shear startup of entangled polymers and its effect on the shear stress undershoot 査読有り国際共著国際誌 Open Access

Yuichi Masubuchi, Dimitris Vlassopoulos, Giovanni Ianniruberto, Giuseppe Marrucci

Journal of Rheology 65 巻 ( 2 ) 頁： 213 - 223 2021年3月

Quantitative bridging between full-atomistic and bead-spring models for polybutadiene and poly(butadiene-styrene) copolymers 査読有り国際誌

Akinori Baba, Yuichi Masubuchi

Journal of Chemical Physics 154 巻 ( 4 ) 頁： 044901-1 - 044901-14 2021年1月

DNA-Chitosan Hydrogels: Formation, Properties, and Functionalization with Catalytic Nanoparticles 査読有り国際共著国際誌

Kohki Morikawa, Yuichi Masubuchi, Yury Shchipunov, Anatoly Zinchenko

ACS Applied Bio Materials 4 巻頁： 1823 - 1832 2021年

Plateau Moduli of Several Single-Chain Slip-Link and Slip-Spring Models 査読有り国際誌 Open Access

Takashi Uneyama, Yuichi Masubuchi

Macromolecules 54 巻 ( 3 ) 頁： 1338 - 1353 2021年

Radial Distribution Functions of Entanglements in Primitive Chain Network Simulations 査読有り国際誌 Open Access

Masubuchi Yuichi, Kida Takumitsu, Doi Yuya, Uneyama Takashi

NIHON REOROJI GAKKAISHI 49 巻 ( 5 ) 頁： 337 - 345 2021年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nihon Reoroji Gakkaishi

Although the entanglement network among polymers has been widely investigated, the spatial distribution of entanglement nodes has been rarely discussed. In this study, we obtained the radial distribution functions (RDFs) for the entanglement nodes from the snapshots of multi-chain slip-link simulations. The model employed in this study is the primitive chain network (PCN) model, which has been validated to reproduce the entangled polymer dynamics semi-quantitatively. The statistics of captured entanglement networks were compared to those reported for the primitive path network extracted by the CReTA procedure from the full-atomistic molecular model of a polyethylene melt. In the range of distance longer than the average strand length, the network structure from PCN does not show any structural correlation, and the intra-chain correlation is close to that for Gaussian chains with non-interacting slip-links. These features are consistent with the CReTA network and the conventional assumptions made for single-chain models. Meanwhile, in the short-range, the structural correlation in PCN is much weaker than that in CReTA. This discrepancy is because the short-range structure in PCN is realized as a result of imposed fluctuations, whereas it is determined by the minimization of the primitive path in CReTA.

DOI： 10.1678/rheology.49.337

Primitive Chain Network Simulations of Entangled Melts of Symmetric and Asymmetric Star Polymers in Uniaxial Elongational Flows 査読有り国際共著国際誌 Open Access

Masubuchi Y., Ianniruberto G., Marrucci G.

Nihon Reoroji Gakkaishi 49 巻 ( 3 ) 頁： 171 - 178 2021年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nihon Reoroji Gakkaishi

Ianniruberto and Marrucci [Macromolecules, 46, 267-275, 2013] developed a theory whereby entangled branched polymers behave like linear ones in fast elongational flows. In order to test such prediction, Huang et al [Macromolecules, 49, 6694-6699, 2016] performed elongational measurements on star polymer melts, indeed revealing that, in fast flows, the elongational viscosity is insensitive to the molecular structure, provided the molecular weight of the "backbone" (spanning the largest end-to-end distance of the molecule) is the same. Inspired by these studies, we here report on results obtained with multi-chain sliplink simulations for symmetric and asymmetric star polymer melts, as well as calculations of the Rouse time of the examined branched structures (not previously determined by Ianniruberto and Marrucci). The simulations semi-quantitatively reproduce the experimental data if the Kuhn-segment orientation-induced reduction of friction (SORF) is accounted for. The observed insensitivity of the nonlinear elongational viscosity to the molecular structure for the same span molar mass may be due to several factors. In the symmetric case, the calculated Rouse time of the star marginally differs from that of the linear molecule, so that possible differences in the observed stress fall within the experimental uncertainty. Secondly, it is possible that flow-induced formation of hooked star pairs (or even larger aggregates) makes the effective Rouse time of the aggregate even closer to that of the linear polymer because the friction center moves towards the branchpoint of the star molecule. In the asymmetric case, it is shown that the stress contributed by the short arms is negligible with respect to that of the long ones. However, such stress reduction is balanced by a dilution effect whereby the unstretched arms reduce SORF as they decrease the Kuhn-segment order parameter of the system. As a result of that dilution, the stress contributed by the backbone is larger. The two effects compensate one another, so that the overall stress is virtually the same of the other architectures.

DOI： 10.1678/rheology.49.171

Elasticity of Randomly Cross-Linked Networks in Primitive Chain Network Simulations 査読有り国際誌 Open Access

Masubuchi Y.

Nihon Reoroji Gakkaishi 49 巻 ( 2 ) 頁： 73 - 78 2021年

担当区分：筆頭著者,　最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nihon Reoroji Gakkaishi

Primitive chain network simulations for randomly cross-linked slip-link networks were performed. For the percolated networks, the stress-strain relationship was compared to the theories by Ball et al. [Polymer, 22, 1010 (1981)] and Rubinstein and Panyukov [Macromolecules, 35, 6670 (2002)]. The simulation results are reasonably reproduced by both theories when the contributions from cross-links and slip-links are determined irrespective of the network structure. The fraction of slip-links contained in the network thus obtained is model dependent, and it does not coincide with the number of active slip-links in the actual networks. This discrepancy between the theories and the simulation results is due to the network inhomogeneity.

DOI： 10.1678/rheology.49.73

Linear Rheological Properties of Poly(Propylene Carbonate) with Different Molecular Weights 査読有り国際誌 Open Access

Yang Lixin, Uneyama Takashi, Masubuchi Yuichi, Doi Yuya

Nihon Reoroji Gakkaishi 49 巻 ( 4 ) 頁： 267 - 274 2021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：一般社団法人日本レオロジー学会

The linear viscoelastic properties of poly(propylene carbonate) (PPC) melts having different molecular weights and narrow molecular weight distributions were studied. Some linear viscoelasticity parameters, including the plateau modulus and zero shear viscosity of PPC, were evaluated. The entanglement molecular weight of PPC was estimated to be 5.9 kg/mol, which is considerably lower than that previously reported for PPC with a broad molecular weight distribution.

DOI： 10.1678/rheology.49.267

Complex Network Representation of the Structure-Mechanical Property Relationships in Elastomers with Heterogeneous Connectivity 査読有り国際誌 Open Access

Yoshifumi Amamoto, Ken Kojio, Atsushi Takahara, Yuichi Masubuchi, TakaakiOhnishi

Patterns 1 巻 ( 8 ) 頁： 100135-1 - 100135-9 2020年11月

Short-time dynamics of a tracer in an ideal gas 査読有り国際誌 Open Access

Nakai Fumiaki, Masubuchi Yuichi, Uneyama Takashi

PHYSICAL REVIEW E 102 巻 ( 3 ) 頁： 032104-1 - 032104-12 2020年9月

Primitive chain network simulations for the interrupted shear response of entangled polymeric liquids 査読有り国際誌 Open Access

Yuichi Masubuchi, Yuya Doi, Takashi Uneyama

SOFT MATTER 16 巻 ( 28 ) 頁： 6654 - 6661 2020年7月

Melts of Linear Polymers in Fast Flows 招待有り査読有り国際共著

Giovanni Ianniruberto, Giuseppe Marrucci, Yuichi Masubuchi

Macromolecules 53 巻 ( 13 ) 頁： 5023 - 5033 2020年7月

Fracture strain of composite with nonuniformly distributed reinforcing fibers 査読有り国際誌

Yamamoto Tetsuya, Masubuchi Yuichi, Doi Masao

JOURNAL OF RHEOLOGY 64 巻 ( 4 ) 頁： 933 - 939 2020年7月

Primitive chain network simulations for H-polymers under fast shear 査読有り国際共著国際誌 Open Access

Masubuchi Yuichi, Ianniruberto Giovanni, Marrucci Giuseppe

SOFT MATTER 16 巻 ( 4 ) 頁： 1056 - 1065 2020年1月

Effects of Constraint-Release on Entangled Polymer Dynamics in Primitive Chain Network Simulations 査読有り国際誌 Open Access

Masubuchi Yuichi

NIHON REOROJI GAKKAISHI 48 巻 ( 1 ) 頁： 37 - 42 2020年

Simulations of Startup Planar Elongation of an Entangled Polymer Melt 査読有り国際誌 Open Access

Takeda Keiko, Masubuchi Yuichi, Sugimoto Masataka, Koyama Kiyohito, Sukumaran Sathish K.

NIHON REOROJI GAKKAISHI 48 巻 ( 1 ) 頁： 43 - 48 2020年

Multi-chain slip-spring simulations for polyisoprene melts 招待有り査読有り国際誌 Open Access

Masubuchi Yuichi, Uneyama Takashi

KOREA-AUSTRALIA RHEOLOGY JOURNAL 31 巻 ( 4 ) 頁： 241 - 248 2019年11月

Retardation of Reaction Kinetics of Polymers due to Entanglement in Post-Gel Stage in Multi-Chain Slip-Spring Simulations 査読有り国際誌

Yuichi Masubuchi, Takashi Uneyama

Soft Matter 15 巻頁： 5109 – 5115 2019年6月

Characterization of critical gel state of polyamides by viscoelastic, thermal, and IR measurements 査読有り国際誌 Open Access

Hirayama Takaya, Uneyama Takashi, Masubuchi Yuichi

RHEOLOGICA ACTA 58 巻 ( 5 ) 頁： 281 - 290 2019年5月

Contraction of Entangled Polymers After Large Step Shear Deformations in Slip-Link Simulations 招待有り査読有り国際誌 Open Access

Masubuchi Yuichi

POLYMERS 11 巻 ( 2 ) 2019年2月

Comparison among multi-chain simulations for entangled polymers under fast shear 査読有り国際誌

Yuichi Masubuchi, Takashi Uneyama

ECS Transactions 88 巻 ( 1 ) 頁： 161-167 - 167 2019年2月

Effect of inertia on linear viscoelasticity of harmonic dumbbell model 査読有り国際誌 Open Access

Takashi Uneyama, Fumiaki Nakai, Yuichi Masubuchi

Nihon Reoroji Gakkaishi 47 巻 ( 4 ) 頁： 143 - 154 2019年

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nihon Reoroji Gakkaishi

The overdamped (inertialess) dumbbell model is widely utilized to study rheological properties of polymers or other soft matters. In most cases, the effect of inertia is merely neglected because the momentum relaxation is much faster than the bond relaxation. We theoretically analyze the effect of inertia on the linear viscoelasticity of the harmonic dumbbell model. We show that the momentum and bond relaxation modes are kinetically coupled and the inertia can affect the bond relaxation if the momentum relaxation is not sufficiently fast. We derive an overdamped Langevin equation for the dumbbell model, which incorporates the weak inertia effect. Our model predicts the bond relaxation dynamics with the weak inertia effect correctly. We discuss how the weak inertia affects the linear viscoelasticity of a simple harmonic dumbbell model and the Rouse model.

DOI： 10.1678/rheology.47.143

Nonlinear Elongational Rheology of Unentangled Polystyrene and Poly(p-tert-butylstyrene) Melts 査読有り国際共著国際誌 Open Access

Matsumiya Yumi, Watanabe Hiroshi, Masubuchi Yuichi, Huang Qian, Hassager Ole

MACROMOLECULES 51 巻 ( 23 ) 頁： 9710 - 9729 2018年12月

Relaxation Dynamics of Surface Fluctuations of Foam Films Decorated by Gel-Like Polymer-Surfactant Complexes 査読有り国際誌

Isoda Takuma, Masubuchi Yuichi, Yamamoto Tetsuya

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 87 巻 ( 10 ) 2018年10月

Relaxation of Rouse Modes for Unentangled Polymers Obtained by Molecular Simulations 査読有り国際誌 Open Access

Yuichi Masubuchi, Hiroto Takata, Yoshifumi Amamoto and Tetsuya Yamamoto

Nihon Reoroji Gakkaishi 46 巻 ( 4 ) 頁： 171-178 2018年9月

Comparison among multi-chain models for entangled polymer dynamics 査読有り国際誌 Open Access

Masubuchi Yuichi, Uneyama Takashi

SOFT MATTER 14 巻 ( 29 ) 頁： 5986-5994 2018年8月

i-Rheo GT: Transforming from Time to Frequency Domain without Artifacts 査読有り国際共著国際誌 Open Access

Manlio Tassieri, Jorge Ramírez, Nikos Ch. Karayiannis, Sathish K. Sukumaran and Yuichi Masubuchi

Macromolecules 51 巻 ( 4 ) 頁： 5055–5068 2018年7月

Coil-globule transitions drive discontinuous volume conserving deformation in locally restrained gels 査読有り国際共著国際誌 Open Access

Yamamoto Tetsuya, Masubuchi Yuichi, Doi Masao

NATURE COMMUNICATIONS 9 巻 2018年5月

Stress undershoot of entangled polymers under fast startup shear flows in primitive chain network simulations 査読有り国際共著国際誌 Open Access

Yuichi Masubuchi, Giovanni Ianniruberto and Giuseppe Marrucci

Nihon Reoroji Gakkaishi ( 46 ) 頁： 23-28 2018年2月

Overview of automotive structural composites technology developments in Japan 招待有り査読有り Open Access

Ishikawa Takashi, Amaoka Kazuaki, Masubuchi Yuichi, Yamamoto Tetsuya, Yamanaka Atsuhiko, Arai Masahiro, Takahashi Jun

Composites Science and Technology 155 巻頁： 221 - 246 2018年2月

Re-Examination of the Effect of the Stretch/Orientation-Induced Reduction of Friction under Equi-Biaxial Elongational Flow via Primitive Chain Network Simulation Using Two Definitions of Orientation Anisotropy 査読有り国際誌 Open Access

Takeda Keiko, Sukumaran Sathish Kumar, Sugimoto Masataka, Koyama Kiyohito, Masubuchi Yuichi

NIHON REOROJI GAKKAISHI 46 巻 ( 3 ) 頁： 145-149 2018年

Orientational cross correlations between entangled branch polymers in primitive chain network simulations 査読有り国際誌 Open Access

Masubuchi Yuichi, Pandey Ankita, Amamoto Yoshifumi, Uneyama Takashi

JOURNAL OF CHEMICAL PHYSICS 147 巻 ( 18 ) 2017年11月

Shear induced formation of lubrication layers of negative normal stress gels 査読有り国際共著国際誌 Open Access

Yamamoto Tetsuya, Masubuchi Yuichi, Doi Masao

SOFT MATTER 13 巻 ( 37 ) 頁： 6515-6520 2017年10月

Primitive chain network simulations of probe rheology 査読有り国際共著国際誌 Open Access

Masubuchi Yuichi, Amamoto Yoshifumi, Pandey Ankita, Liu Cheng-Yang

SOFT MATTER 13 巻 ( 37 ) 頁： 6585-6593 2017年10月

Onset of static and dynamic universality among molecular models of polymers 査読有り国際誌 Open Access

Takahashi Kazuaki Z., Nishimura Ryuto, Yamato Nobuyoshi, Yasuoka Kenji, Masubuchi Yuichi

SCIENTIFIC REPORTS 7 巻 2017年9月

Relaxation Dynamics of the Normal Stress of Polymer Gels 査読有り国際誌 Open Access

Yamamoto Tetsuya, Masubuchi Yuichi, Doi Masao

MACROMOLECULES 50 巻 ( 13 ) 頁： 5208-5213 2017年7月

Large Network Swelling and Solvent Redistribution Are Necessary for Polymer Gels to Show Negative Normal Stress 査読有り国際誌 Open Access

Yamamoto Tetsuya, Masubuchi Yuichi, Doi Masao

ACS MACRO LETTERS 6 巻 ( 5 ) 頁： 512-514 2017年5月

Extensional Step Strain Rate Experiments on an Entangled Polymer Solution 査読有り国際共著国際誌

Bhattacharjee P. K., Nguyen D. A., Masubuchi Y., Sridhar T.

MACROMOLECULES 50 巻 ( 1 ) 頁： 386-395 2017年1月

Molecular Dynamics Simulations for Resolving Scaling Laws of Polyethylene Melts 査読有り国際誌 Open Access

Takahashi Kazuaki Z., Nishimura Ryuto, Yasuoka Kenji, Masubuchi Yuichi

POLYMERS 9 巻 ( 1 ) 2017年1月

Inter-Chain Cross-Correlation in Multi-Chain Slip-Link Simulations without Force Balance at Entanglements 査読有り国際誌 Open Access

Yuichi Masubuchi, Ankita Pandey, Yoshifumi Amamoto

NIHON REOROJI GAKKAISHI 45 巻 ( 4 ) 頁： 175-180 2017年

Critical test of bead-spring model to resolve the scaling laws of polymer melts: a molecular dynamics study 査読有り国際誌

Takahashi Kazuaki Z., Yamato Nobuyoshi, Yasuoka Kenji, Masubuchi Yuichi

MOLECULAR SIMULATION 43 巻 ( 13-16 ) 頁： 1196-1201 2017年

A Multichain Slip-Spring Dissipative Particle Dynamics Simulation Method for Entangled Polymer Solutions 査読有り国際共著国際誌

Masubuchi Yuichi, Langeloth Michael, Boehm Michael C., Inoue Tadashi, Mueller-Plathe Florian

MACROMOLECULES 49 巻 ( 23 ) 頁： 9186-9191 2016年12月

Orientational Cross-Correlation in Entangled Binary Blends in Primitive Chain Network Simulations 査読有り国際誌

Masubuchi Yuichi, Amamoto Yoshifumi

MACROMOLECULES 49 巻 ( 23 ) 頁： 9258-9265 2016年12月

Distribution function of fiber length in thermoplastic composites 査読有り国際誌 Open Access

Masubuchi Yuichi, Terada Mariko, Yamanaka Atsuhiko, Yamamoto Tetsuya, Ishikawa Takashi

COMPOSITES SCIENCE AND TECHNOLOGY 134 巻頁： 43-48 2016年10月

Dielectric Relaxation and Ionic Conductivity of a Chitosan/Poly(ethylene oxide) Blend Doped with Potassium and Calcium Cations 査読有り国際共著国際誌 Open Access

Rakkapao Natthida, Watanabe Hiroshi, Matsumiya Yumi, Masubuchi Yuichi

NIHON REOROJI GAKKAISHI 44 巻 ( 2 ) 頁： 89-97 2016年

Effect of Osmotic Force on Orientational Cross-correlation in Primitive Chain Network Simulation 査読有り国際誌 Open Access

Masubuchi Yuichi, Amamoto Yoshifumi

NIHON REOROJI GAKKAISHI 44 巻 ( 4 ) 頁： 219-222 2016年

Stress-Optical Relationship in Bead-Spring Simulations for Entangled Polymers under Start-up Shear Flows 査読有り国際誌

Masubuchi Yuichi, Watanabe Hiroshi

NIHON REOROJI GAKKAISHI 44 巻 ( 1 ) 頁： 65-68 2016年

An Approximate Analytical Solution of Flow Fields at the Front of Poiseuille Flows 査読有り国際誌 Open Access

Yamamoto Tetsuya, Masubuchi Yuichi

NIHON REOROJI GAKKAISHI 44 巻 ( 4 ) 頁： 211-217 2016年

PASTA and NAPLES: Rheology Simulator 査読有り国際誌

Masubuchi Yuichi

COMPUTER SIMULATION OF POLYMERIC MATERIALS: APPLICATIONS OF THE OCTA SYSTEM 頁： 101 - 127 2016年

Effects of degree of freedom below entanglement segment on relaxation of polymer configuration under fast shear in multi-chain slip-spring simulations 査読有り国際誌

Yuichi Masubuchi

JOURNAL OF CHEMICAL PHYSICS 143 巻 ( 22 ) 頁： [224905-1]-[224905-6] 2015年12月

Primitive chain network simulations for elongational viscosity of bidisperse polystyrene melts 招待有り査読有り国際誌 Open Access

K. Takeda, S. K. Sukumaran, M. Sugimoto, K. Koyama and Y. Masubuchi

Advanced Modeling and Simulation in Engineering Sciences 2 巻頁： 11-24 2015年6月

Viscoelastic Relaxation of Rouse Chains undergoing Head-to-Head Association and Dissociation: Motional Coupling through Chemical Equilibrium 査読有り国際誌

Watanabe Hiroshi, Matsumiya Yumi, Masubuchi Yuichi, Urakawa Osamu, Inoue Tadashi

MACROMOLECULES 48 巻 ( 9 ) 頁： 3014-3030 2015年5月

Test of the Stretch/Orientation-Induced Reduction of Friction for Biaxial Elongational Flow via Primitive Chain Network Simulation 査読有り国際誌 Open Access

Takeda Keiko, Sukumaran Sathish Kumar, Sugimoto Masataka, Koyama Kiyohito, Masubuchi Yuichi

NIHON REOROJI GAKKAISHI 43 巻 ( 3-4 ) 頁： 63-69 2015年

Characterization of Transitional Behavior of the Facial Wash Foams via Dynamic Viscoelastic Measurements 査読有り国際誌 Open Access

Ohmura Kenji, Minami Tadayasu, Yanagi Masaaki, Mori Naoya, Nakamura Takeshi, Masubuchi Yuichi

NIHON REOROJI GAKKAISHI 43 巻 ( 3-4 ) 頁： 71-75 2015年

Reptation and constraint release dynamics in bidisperse polymer melts 査読有り国際共著国際誌

Langeloth Michael, Masubuchi Yuichi, Boehm Michael C., Mueller-Plathe Florian

JOURNAL OF CHEMICAL PHYSICS 141 巻 ( 19 ) 2014年11月

Dielectric and Viscoelastic Behavior of Star-Branched Polyisoprene: Two Coarse-Grained Length Scales in Dynamic Tube Dilation 査読有り国際共著国際誌

Matsumiya Yumi, Masubuchi Yuichi, Inoue Tadashi, Urakawa Osamu, Liu Chen-Yang, van Ruymbeke Evelyne, Watanabe Hiroshi

MACROMOLECULES 47 巻 ( 21 ) 頁： 7637-7652 2014年11月

Origin of Stress Overshoot under Start-up Shear in Primitive Chain Network Simulation 査読有り国際誌

Masubuchi Yuichi, Watanabe Hiroshi

ACS MACRO LETTERS 3 巻 ( 11 ) 頁： 1183-1186 2014年11月

Test of Orientation/Stretch-Induced Reduction of Friction via Primitive Chain Network Simulations for Polystyrene, Polyisoprene, and Poly(n-butyl acrylate) 査読有り国際誌

Masubuchi Yuichi, Matsumiya Yumi, Watanabe Hiroshi

MACROMOLECULES 47 巻 ( 19 ) 頁： 6768-6775 2014年10月

Primitive Chain Network Simulations for Pom-Pom Polymers in Uniaxial Elongational Flows 査読有り国際共著国際誌

Masubuchi Yuichi, Matsumiya Yumi, Watanabe Hiroshi, Marrucci Giuseppe, Ianniruberto Giovanni

MACROMOLECULES 47 巻 ( 10 ) 頁： 3511-3519 2014年5月

Simulating the Flow of Entangled Polymers 招待有り査読有り

Yuichi Masubuchi

ANNUAL REVIEW OF CHEMICAL AND BIOMOLECULAR ENGINEERING 5 巻頁： 11 - 33 2014年2月

Rheo-Dielectric Responses of Entangled cis-Polyisoprene under Uniform Steady Shear and LAOS 査読有り国際誌

Horio Kazushi, Uneyama Takashi, Matsumiya Yumi, Masubuchi Yuichi, Watanabe Hiroshi

MACROMOLECULES 47 巻 ( 1 ) 頁： 246-255 2014年1月

Concept of Stretch/Orientation-Induced Friction Reduction Tested with a Simple Molecular Constitutive Equation 査読有り国際誌 Open Access

Yaoita Takatoshi, Masubuchi Yuichi, Watanabe Hiroshi

NIHON REOROJI GAKKAISHI 42 巻 ( 3 ) 頁： 207-213 2014年

Recovering the reptation dynamics of polymer melts in dissipative particle dynamics simulations via slip-springs 査読有り国際共著国際誌

Langeloth Michael, Masubuchi Yuichi, Boehm Michael C., Mueller-Plathe Florian

JOURNAL OF CHEMICAL PHYSICS 138 巻 ( 10 ) 2013年3月

Nonlinear Stress Relaxation of Scarcely Entangled Chains in Primitive Chain Network Simulations 査読有り国際誌 Open Access

Furuichi Kenji, Nonomura Chisato, Masubuchi Yuichi, Watanabe Hiroshi

NIHON REOROJI GAKKAISHI 41 巻 ( 1 ) 頁： 13-19 2013年

Stretch/orientation Induced Acceleration in Stress Relaxation in Coarse-grained Molecular Dynamics Simulations 査読有り国際共著国際誌 Open Access

Masubuchi Yuichi, Yaoita Takatoshi, Matsumiya Yumi, Watanabe Hiroshi, Ianniruberto Giovanni, Marrucci Giuseppe

NIHON REOROJI GAKKAISHI 41 巻 ( 1 ) 頁： 35-37 2013年

Cross-Correlation Contributions to Orientational Relaxations in Primitive Chain Network Simulations 査読有り国際誌

Masubuchi Yuichi, Sukumaran Sathish K.

NIHON REOROJI GAKKAISHI 41 巻 ( 1 ) 頁： 1-6 2013年

Multi-chain slip-spring model for entangled polymer dynamics 査読有り国際誌 Open Access

Uneyama Takashi, Masubuchi Yuichi

JOURNAL OF CHEMICAL PHYSICS 137 巻 ( 15 ) 2012年10月

A multiscale simulation of polymer processing using parameter-based bridging in melt rheology 査読有り国際誌

Masubuchi Yuichi, Uneyama Takashi, Saito Keiichi

JOURNAL OF APPLIED POLYMER SCIENCE 125 巻 ( 4 ) 頁： 2740-2747 2012年8月

Primitive Chain Network Simulation of Elongational Flows of Entangled Linear Chains: Stretch/Orientation-induced Reduction of Monomeric Friction 査読有り国際共著国際誌

Yaoita Takatoshi, Isaki Takeharu, Masubuchi Yuichi, Watanabe Hiroshi, Ianniruberto Giovanni, Marrucci Giuseppe

MACROMOLECULES 45 巻 ( 6 ) 頁： 2773-2782 2012年3月

Primitive chain network simulations for comb-branched polymer under step shear deformations 査読有り国際誌

Masubuchi Yuichi, Matsumiya Yumi, Watanabe Hiroshi, Shiromoto Seiji, Tsutsubuchi Masaaki, Togawa Yoshiaki

RHEOLOGICA ACTA 51 巻 ( 3 ) 頁： 193-200 2012年3月

Effective Value of the Dynamic Dilution Exponent in Bidisperse Linear Polymers: From 1 to 4/3 査読有り国際共著国際誌

van Ruymbeke E., Masubuchi Y., Watanabe H.

MACROMOLECULES 45 巻 ( 4 ) 頁： 2085-2098 2012年2月

Rheo-Dielectric Behavior of Soft Matters 国際誌

Hiroshi Watanabe, Yumi Matsumiya, Kazushi Horio, Yuichi Masubuchi, Takashi Uneyama

Series in Soft Condensed Matter 頁： 37 - 87 2012年2月

Soft-core Interaction Between Entanglement Segments for Primitive Chain Network Simulations 査読有り国際誌 Open Access

Okuda Satoru, Uneyama Takashi, Inoue Yasuhiro, Masubuchi Yuichi, Hojo Masaki

NIHON REOROJI GAKKAISHI 40 巻 ( 1 ) 頁： 21-30 2012年

Primitive Chain Network Simulation of Elongational Flows of Entangled Linear Chains: Role of Finite Chain Extensibility 査読有り国際共著国際誌

Yaoita Takatoshi, Isaki Takeharu, Masubuchi Yuichi, Watanabe Hiroshi, Ianniruberto Giovanni, Marrucci Giuseppe

MACROMOLECULES 44 巻 ( 24 ) 頁： 9675-9682 2011年12月

Precise Analyses of Short-Time Relaxation at Asymmetric Polystyrene Interface in Terms of Molecular Weight by Time-Resolved Neutron Reflectivity Measurements 査読有り国際共著国際誌

Kawaguchi Daisuke, Nelson Andrew, Masubuchi Yuichi, Majewski Jaroslaw P., Torikai Naoya, Yamada Norifumi L., Sarah A. R. Siti, Takano Atsushi, Matsushita Yushu

MACROMOLECULES 44 巻 ( 23 ) 頁： 9424-9433 2011年12月

Detailed balance condition and effective free energy in the primitive chain network model 査読有り国際誌 Open Access

Uneyama Takashi, Masubuchi Yuichi

JOURNAL OF CHEMICAL PHYSICS 135 巻 ( 18 ) 2011年11月

Numerical study of chain conformation on shear banding using diffusive Rolie-Poly model 査読有り国際誌

Chung Changkwon, Uneyama Takashi, Masubuchi Yuichi, Watanabe Hiroshi

RHEOLOGICA ACTA 50 巻 ( 9-10 ) 頁： 753-766 2011年10月

Miscibility of chitosan/poly(ethylene oxide) blends and effect of doping alkali and alkali earth metal ions on chitosan/PEO interaction 査読有り国際共著国際誌

Rakkapao Natthida, Vao-soongnern Visit, Masubuchi Yuichi, Watanabe Hiroshi

POLYMER 52 巻 ( 12 ) 頁： 2618-2627 2011年5月

Primitive chain network simulations for asymmetric star polymers 査読有り国際誌

Masubuchi Yuichi, Yaoita Takatoshi, Matsumiya Yumi, Watanabe Hiroshi

JOURNAL OF CHEMICAL PHYSICS 134 巻 ( 19 ) 2011年5月

Dynamics of Polyisoprene-Poly(p-tert-butylstyrene) Diblock Copolymer in Disordered State 査読有り国際誌

Chen Quan, Matsumiya Yumi, Masubuchi Yuichi, Watanabe Hiroshi, Inoue Tadashi

MACROMOLECULES 44 巻 ( 6 ) 頁： 1585-1602 2011年3月

Chain contraction and nonlinear stress damping in primitive chain network simulations 査読有り国際誌 Open Access

Furuichi Kenji, Nonomura Chisato, Masubuchi Yuichi, Watanabe Hiroshi

JOURNAL OF CHEMICAL PHYSICS 133 巻 ( 17 ) 2010年11月

Structure of entangled polymer network from primitive chain network simulations 査読有り国際共著国際誌 Open Access

Masubuchi Yuichi, Uneyama Takashi, Watanabe Hiroshi, Ianniruberto Giovanni, Greco Francesco, Marrucci Giuseppe

JOURNAL OF CHEMICAL PHYSICS 132 巻 ( 13 ) 2010年4月

Rheological and Dielectric Behavior of Polyisoprene under Pressurized Carbon Dioxide 査読有り国際誌 Open Access

Uno Akiko, Matsumiya Yumi, Masubuchi Yuichi, Watanabe Hiroshi

NIHON REOROJI GAKKAISHI 38 巻 ( 3 ) 頁： 117-123 2010年

プリミティブチェーンネットワークシミュレーションによる高分子材料の応力緩和挙動の予測招待有り査読有り国際誌

増渕雄一

日本ゴム協會誌 82 巻 ( 11 ) 頁： 459 - 463 2009年11月

担当区分：筆頭著者,　最終著者,　責任著者記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人日本ゴム協会

Prediction of relaxation behavior of polymeric materials from molecular architecture attracts industrial interests and scientific challenges. In this study a coarse-grained molecular model called primitive chain network model is developed. The model is capable for quantitative prediction of linear and non-linear viscoelasticity of entangled polymers. Also it is indicated that the simulation for cross-linked network is fair, though quantitative test is demanded.

DOI： 10.2324/gomu.82.459

Primitive chain network simulations for entangled DNA solutions 査読有り国際共著国際誌 Open Access

Masubuchi Yuichi, Furuichi Kenji, Horio Kazushi, Uneyama Takashi, Watanabe Hiroshi, Ianniruberto Giovanni, Greco Francesco, Marrucci Giuseppe

JOURNAL OF CHEMICAL PHYSICS 131 巻 ( 11 ) 2009年9月

Formation of globules and aggregates of DNA chains in DNA/polyethylene glycol/monovalent salt aqueous solutions 査読有り国際誌 Open Access

Kawakita H., Uneyama T., Kojima M., Morishima K., Masubuchi Y., Watanabe H.

JOURNAL OF CHEMICAL PHYSICS 131 巻 ( 9 ) 2009年9月

Wall boundary model for primitive chain network simulations 査読有り国際誌 Open Access

Okuda Satoru, Inoue Yasuhiro, Masubuchi Yuichi, Uneyama Takasi, Hojo Masaki

JOURNAL OF CHEMICAL PHYSICS 130 巻 ( 21 ) 2009年6月

DNA Diffusion in Aqueous Solution in Presence of Suspended Particles 査読有り国際誌

Sato Hiroki, Masubuchi Yuichi, Watanabe Hiroshi

JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS 47 巻 ( 11 ) 頁： 1103-1111 2009年6月

A Theoretical Analysis of Rheodielectric Response of Type-A Polymer Chains 査読有り国際共著国際誌 Open Access

Uneyama Takashi, Masubuchi Yuichi, Horio Kazushi, Matsumiya Yumi, Watanabe Hiroshi, Pathak Jai A., Roland C. Michael

JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS 47 巻 ( 11 ) 頁： 1039-1057 2009年6月

Rheological Properties of Native Silk Fibroins from Domestic and Wild Silkworms, and Flow Analysis in Each Spinneret by a Finite Element Method 査読有り国際共著国際誌

Moriya Motoaki, Roschzttardtz Frederico, Nakahara Yusuke, Saito Hitoshi, Masubuchi Yuichi, Asakura Tetsuo

BIOMACROMOLECULES 10 巻 ( 4 ) 頁： 929-935 2009年4月

Primitive Chain Network Simulations of Conformational Relaxation for Individual Molecules in the Entangled State. II. Retraction from Stretched States 査読有り国際共著国際誌 Open Access

Masubuchi Yuichi, Uneyama Takashi, Watanabe Hiroshi, Ianniruberto Giovanni, Greco Francesco, Marrucci Giuseppe

NIHON REOROJI GAKKAISHI 37 巻 ( 2 ) 頁： 65-68 2009年

Micro-computerized tomographic observation of the spinning apparatus in Bombyx mori silkworms 査読有り国際共著国際誌

Moriya Motoaki, Ohgo Kosuke, Masubuchi Yuichi, Knight David P., Asakura Tetsuo

POLYMER 49 巻 ( 26 ) 頁： 5665-5669 2008年12月

Component Dynamics in Polyisoprene/Poly(4-tert-butylstyrene) Miscible Blends 査読有り国際誌

Chen Quan, Matsumiya Yumi, Masubuchi Yuichi, Watanabe Hiroshi, Inoue Tadashi

MACROMOLECULES 41 巻 ( 22 ) 頁： 8694-8711 2008年11月

Comparison among Slip-Link Simulations of Bidisperse Linear Polymer Melts 査読有り国際共著国際誌

Masubuchi Yuichi, Watanabe Hiroshi, Ianniruberto Giovanni, Greco Francesco, Marrucci Giuseppe

MACROMOLECULES 41 巻 ( 21 ) 頁： 8275-8280 2008年11月

Entangled polymer orientation and stretch under large step shear deformations in primitive chain network simulations 査読有り国際共著国際誌

Furuichi Kenji, Nonomura Chisato, Masubuchi Yuichi, Watanabe Hiroshi, Ianniruberto Giovanni, Greco Francesco, Marrucci Giuseppe

RHEOLOGICA ACTA 47 巻 ( 5-6 ) 頁： 591-599 2008年7月

The effect of CO2 pressure on viscoelasticity of LDPE 査読有り国際誌

Ouchi S., Masubuchi Y., Shikuma H.

INTERNATIONAL POLYMER PROCESSING 23 巻 ( 2 ) 頁： 173-177 2008年5月

Statics, linear, and nonlinear dynamics of entangled polystyrene melts simulated through the primitive chain network model 査読有り国際共著国際誌 Open Access

Yaoita Takatoshi, Isaki Takeharu, Masubuchi Yuichi, Watanabe Hiroshi, Ianniruberto Giovanni, Greco Francesco, Marrucci Giuseppe

JOURNAL OF CHEMICAL PHYSICS 128 巻 ( 15 ) 2008年4月

Flow analysis of aqueous solution of silk fibroin in the spinneret of Bombyx mori silkworm by combination of viscosity measurement and finite element method calculation 査読有り国際誌

Moriya Motoaki, Ohgo Kosuke, Masubuchi Yuichi, Asakura Tetsuo

POLYMER 49 巻 ( 4 ) 頁： 952-956 2008年2月

Quantitative comparison of primitive chain network simulations with literature data of linear viscoelasticity for polymer melts 査読有り国際共著国際誌

Masubuchi Yuichi, Lanniruberto Giovanni, Greco Francesco, Marrucci Giuseppe

JOURNAL OF NON-NEWTONIAN FLUID MECHANICS 149 巻 ( 1-3 ) 頁： 87-92 2008年2月

Primitive chain network simulations of conformational relaxation for individual molecules in the entangled state 査読有り国際共著国際誌 Open Access

Masubuchi Yuichi, Watanabe Hiroshi, Ianniruberto Giovanni, Greco Francesco, Marrucci Giuseppe

NIHON REOROJI GAKKAISHI 36 巻 ( 4 ) 頁： 181-185 2008年

A molecular dynamics simulation study on polymer networks of end-linked flexible or rigid chains 査読有り国際誌

Hosono Nobuhiko, Masubuchi Yuichi, Furukawa Hidemitsu, Watanabe Toshiyuki

JOURNAL OF CHEMICAL PHYSICS 127 巻 ( 16 ) 2007年10月

Spontaneous self-assembly process for threadlike micelles 査読有り国際誌

Arai Noriyoshi, Yasuoka Kenji, Masubuchi Yuichi

JOURNAL OF CHEMICAL PHYSICS 126 巻 ( 24 ) 2007年6月

単一分子が描き出すからみ合い招待有り査読有り

増渕雄一

高分子 56 巻 ( 6 ) 頁： 412 - 415 2007年6月

担当区分：筆頭著者,　最終著者,　責任著者記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：The Society of Polymer Science, Japan

高分子溶融体のダイナミクスを支配するといわれる"からみ合い"だが,管模型などのからみ合いを前提とした理論の発展とは対照的にその具体的な描像の理解は遅れている。本稿では分子シミュレーションによる単一分子観察を中心に,からみ合いそのものに関する最近の研究動向を紹介する。

DOI： 10.1295/kobunshi.56.412

その他リンク： https://jlc.jst.go.jp/DN/JALC/00295142546?from=CiNii

Photochemical control of network structure in gels and photo-induced changes in their viscoelastic properties 査読有り国際誌

Hosono Nobuhiko, Furukawa Hidemitsu, Masubuchi Yuichi, Watanabe Toshiyuki, Horie Kazuyuki

COLLOIDS AND SURFACES B-BIOINTERFACES 56 巻 ( 1-2 ) 頁： 285-289 2007年4月

Rheological properties of poly(methyl methacrylate)/rigid ladderlike polyphenylsilsesquioxane blends 査読有り国際共著国際誌

Li Guizhi, Matsuda T., Nishioka A., Liang Kaiwen, Masubuchi Y., Koyama K., Pittman Charles U. Jr.

JOURNAL OF APPLIED POLYMER SCIENCE 104 巻 ( 1 ) 頁： 352-359 2007年4月

Primitive chain network simulations of damping functions for shear, uniaxial, biaxial and planar deformations 査読有り国際共著国際誌 Open Access

Furuichi Kenji, Nonomura Chisato, Masubuchi Yuichi, Ianniruberto Giovanni, Greco Francesco, Marrucci Giuseppe

NIHON REOROJI GAKKAISHI 35 巻 ( 2 ) 頁： 73-77 2007年

Primitive chain network simulations for branched polymers 査読有り国際共著国際誌

Masubuchi Yuichi, Ianniruberto Giovanni, Greco Francesco, Marrucci Giuseppe

RHEOLOGICA ACTA 46 巻 ( 2 ) 頁： 297-303 2006年12月

Viscoelasticity of LDPE with CO2 査読有り国際誌

Ouchi S., Masubuchi Y., Shikuma H.

Polymer Preprints Japan 55 巻 ( 2 ) 頁： 3740 - 3741 2006年12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：Polymer Preprints Japan

Viscoelasticity of LDPE/CO<inf>2</inf> was measured using a rheometer equipped with a pressure cell using magnetic drive. The values that were measured under supercritical CO<inf>2</inf> and atmospheric air were relatively discussed. The storage modulus and loss modulus of LDPE with supercritical CO<inf>2</inf> were reduced and shifted to high frequency compared to those of LDPE without CO<inf>2</inf>. The shift factor can be approximately described by an exponential factor of CO<inf>2</inf> pressure.

Primitive chain network model for block copolymers 招待有り査読有り国際共著国際誌

Masubuchi Yuichi, Ianniruberto Giovanni, Greco Francesco, Marrucci Giuseppe

JOURNAL OF NON-CRYSTALLINE SOLIDS 352 巻 ( 42-49 ) 頁： 5001-5007 2006年11月

Biased hooking for primitive chain network simulations of block copolymers 招待有り査読有り国際共著国際誌

Masubuchi Y, Ianniruberto G, Marrucci G, Greco F

KOREA-AUSTRALIA RHEOLOGY JOURNAL 18 巻 ( 2 ) 頁： 99-102 2006年6月

Pre-averaged sampling on the entanglement kinetics for polymer dynamics 査読有り国際誌

Horio Kazushi, Masubuchi Yuichi

MACROMOLECULAR SYMPOSIA 242 巻頁： 140-145 2006年

The influence of heat treatment on uniaxial elongational flow behavior of PS/SBS blends 査読有り国際誌 Open Access

Nishioka Akihiro, Minegishi Akinari, Takahashi Tatsuhiro, Koda Tomonori, Masubuchi Yuichi, Takimoto Jun-ichi, Koyama Kiyohito

NIHON REOROJI GAKKAISHI 34 巻 ( 4 ) 頁： 189-197 2006年

Highly entangled polymer primitive chain network simulations based on dynamic tube dilation (vol 121, pg 12650, 2004) 査読有り国際共著国際誌

Yaoita T, Isaki T, Masubuchi Y, Watanabe H, Ianniruberto G, Greco F, Marrucci G

JOURNAL OF CHEMICAL PHYSICS 122 巻 ( 20 ) 頁： . 2005年5月

Rheological properties of polystyrene blends with rigid ladderlike polyphenylsilsesquioxane 査読有り国際共著国際誌

Li GZ, Matsuda T, Nishioka A, Miyata K, Masubuchi Y, Koyama K, Pittman CU

JOURNAL OF APPLIED POLYMER SCIENCE 96 巻 ( 3 ) 頁： 706-713 2005年5月

A novel elongational rheology control of PS by SBS and dicumyl peroxide 査読有り国際誌 Open Access

Minegishi A, Nishioka A, Takahashi T, Masubuchi Y, Takimoto J, Koyama K

NIHON REOROJI GAKKAISHI 33 巻 ( 3 ) 頁： 141-144 2005年

Highly entangled polymer primitive chain network simulations based on dynamic tube dilation 査読有り国際共著国際誌 Open Access

Yaoita T, Isaki T, Masubuchi Y, Watanabe H, Ianniruberto G, Greco F, Marrucci G

JOURNAL OF CHEMICAL PHYSICS 121 巻 ( 24 ) 頁： 12650-12654 2004年12月

Adaptive Shape Reconfiguration of a Decentralized Motile System Exploiting Molecular Dynamics and Stokesian Dynamics Methods 査読有り国際誌

Shimizu M., Ishiguro A., Takahashi M., Kawakatsu T., Masubuchi Y., Doi M.

Journal of Robotics and Mechatronics 16 巻 ( 3 ) 頁： 271 - 277 2004年6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：Journal of Robotics and Mechatronics

This paper discusses a fully decentralized algorithm able to create a coherent swarm of autonomous mobile robots from the viewpoint of computational physics. To this end, we focus on Molecular Dynamics and Stokesian Dynamics, both of which are widely used to investigate many-body systems. To verify the feasibility of our approach, this idea has been implemented to a swarm of 2-D radio-connected autonomous mobile robots as a practical example. Simulation results indicate that the proposed algorithm can control the shape of the swarm appropriately based on the current situation without losing the coherence of the swarm nor exchanging global information among modules. Furthermore, we found that local interaction used to exploit Stokesian Dynamics plays an essential role to maintain the coherence of the swarm particularly in an unstructured environment.

DOI： 10.20965/jrm.2004.p0271

Molecular simulations of the long-time behaviour of entangled polymeric liquids by the primitive chain network model 招待有り査読有り国際共著国際誌

Masubuchi Y, Ianniruberto G, Greco F, Marrucci G

MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING 12 巻 ( 3 ) 頁： S91-S100 2004年5月

Primitive chain network simulations on dielectric relaxation of linear polymers under shear flow 査読有り国際共著国際誌 Open Access

Masubuchi Y, Watanabe H, Ianniruberto G, Greco F, Marrucci G

NIHON REOROJI GAKKAISHI 32 巻 ( 4 ) 頁： 197-202 2004年

Generalization of the Ohta-Kawasaki theory for microphase separation of block copolymer melts 査読有り国際誌

Uneyama T, Masubuchi Y, Takimoto JI, Doi M

SLOW DYNAMICS IN COMPLEX SYSTEMS 708 巻頁： 446-447 2004年

Primitive chain network model for entangled polymer blends 査読有り国際共著国際誌

Masubuchi Y, Takimoto JI, Doi M, Ianniruberto G, Greco F, Marrucci G

SLOW DYNAMICS IN COMPLEX SYSTEMS 708 巻頁： 261-262 2004年

ジメチルジオクタデシルアンモニウムクロライドとポリ酢酸ビニルエマルションおよびそれらの混合物の吸着面の接触角の測定による親水性能の評価査読有り

樋口才二, 増渕雄一, 三俣哲, 瀧本淳一, 小山清人, 鈴木淳

日本家政学会誌 55 巻 ( 2 ) 頁： 145 - 151 2004年

Entanglement molecular weight and frequency response of sliplink networks 査読有り国際共著国際誌

Masubuchi Y, Ianniruberto G, Greco F, Marrucci G

JOURNAL OF CHEMICAL PHYSICS 119 巻 ( 13 ) 頁： 6925-6930 2003年10月

Crystallization kinetics of polypropylene under high pressure and steady shear flow 査読有り国際誌

Watanabe K, Suzuki T, Masubuchi Y, Taniguchi T, Takimoto J, Koyama K

POLYMER 44 巻 ( 19 ) 頁： 5843-5849 2003年9月

The effect of pre-thermal history on shear and uniaxial elongational viscosity of a tetrafluoroethylene/hexafluoropropylene copolymer near the crystal melting transition 査読有り国際誌

Kurose T, Takahashi T, Nishioka A, Masubuchi Y, Takimoto J, Koyama K

RHEOLOGICA ACTA 42 巻 ( 4 ) 頁： 338-344 2003年7月

Direct observation of polymer crystallization process under shear by a shear flow observation system 査読有り国際誌

Watanabe K, Nagatake W, Takahashi T, Masubuchi Y, Takimoto J, Koyama K

POLYMER TESTING 22 巻 ( 1 ) 頁： 101-108 2003年2月

Coherent swarming from local interaction by exploiting molecular dynamics and Stokesian Dynamics methods 査読有り国際誌

Shimizu M, Ishiguro A, Kawakatsu T, Masubuchi Y, Doi M

IROS 2003: PROCEEDINGS OF THE 2003 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS, VOLS 1-4 頁： 1614-1619 2003年

Adaptive swarming by exploiting hydrodynamic interaction based on Stokesian Dynamics Method 査読有り国際誌

Shimizu M, Ishiguro A, Kawakatsu T, Masubuchi Y, Doi M

SICE 2003 ANNUAL CONFERENCE, VOLS 1-3 頁： 1546-1551 2003年

ジメチルジオクタデシルアンモニウムクロライドとポリ酢酸ビニルエマルションを含む真空乾燥した寒天ゲルの吸水性能査読有り

樋口才二, 増渕雄一, 三俣哲, 瀧本淳一, 小山清人, 鈴木淳

日本家政学会誌 54 巻 ( 5 ) 頁： 343 - 349 2003年

Reversibility of the ER effect in immiscible liquid blends 査読有り国際誌

Yamamoto S, Masubuchi Y, Takimoto J

INTERNATIONAL JOURNAL OF MODERN PHYSICS B 16 巻 ( 17-18 ) 頁： 2468-2473 2002年7月

The contribution of columnar structure to the stress in Er polymeric blends in a shear flow 査読有り国際共著国際誌

Riha P, Takimoto J, Masubuchi Y, Koyama K

INTERNATIONAL JOURNAL OF MODERN PHYSICS B 16 巻 ( 17-18 ) 頁： 2542-2547 2002年7月

Simulation study on molecular relaxation in ionomer melts 査読有り国際誌

Masubuchi Y, Nishioka A, Takimoto JI, Koyama K

POLYMER 43 巻 ( 1 ) 頁： 239-242 2002年1月

Rheological characterization of ionic bonding in ethylene-ionomer melts with low neutralization degree 査読有り国際誌

Nishioka A, Takahashi T, Masubuchi Y, Takimoto J, Koyama K

JOURNAL OF RHEOLOGY 46 巻 ( 6 ) 頁： 1325-1339 2002年

Melt rheology of polypropylene containing small amounts of high molecular weight chain. I. Shear flow 査読有り国際誌

Sugimoto M, Masubuchi Y, Takimoto J, Koyama K

JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS 39 巻 ( 21 ) 頁： 2692-2704 2001年11月

Brownian simulations of a network of reptating primitive chains 査読有り国際共著国際誌

Masubuchi Y, Takimoto JI, Koyama K, Ianniruberto G, Marrucci G, Greco F

JOURNAL OF CHEMICAL PHYSICS 115 巻 ( 9 ) 頁： 4387-4394 2001年9月

潤滑圧縮法を用いた高分子溶融体の平面伸長粘度および平面伸長応力緩和測定査読有り国際誌

西岡昭博, 増渕雄一, 滝本淳一, 小山清人

成形加工 13 巻 ( 8 ) 頁： 563 - 570 2001年8月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人プラスチック成形加工学会

A technique to measure planar elongational viscosity and step-planar stress relaxation, by using a lubricated squeeze flow method with PS and LDPE, has been optimized and established. The effect of experimental conditions, i.e., the viscosity of silicone oil as a lubricant, appeared in the measurement of the planar elongational viscosity. The dependence of the uniform planar deformation behavior on the silicone oil viscosity was greater in LDPE than in PS. A high viscosity silicone oil (3.0×102Pa-s) was chosen to minimize the loss of lubricant. Although the step-planar stress relaxation experiments required speeds that exceeded the testing machine specification to achieve the step deformation, this problem was successfully solved by inserting a metal spacer between the lower plate and the sample. The high viscosity silicone oil produced uniform deformation in both materials with minimal loss of the lubricant, however, the high viscosity of the silicone oil was believed to lead larger measured G0(t) results than the predicted values. The silicone oil viscosity was optimized at a lower value of 1.0×101Pa-s which minimized the influence of the silicone oil on the results while still producing substantial lubricity. The measurement of planar elongational viscosity by using this optimal silicone oil showed strain-hardening in both samples, with LDPE showing a stronger dependence. “Time-strain separability” within a certain time period was confirmed for the step planar stress relaxation modulus under the optimized conditions.

DOI： 10.4325/seikeikakou.13.563

Melt rheology of polypropylene containing small amounts of high-molecular-weight chain. 2. Uniaxial and biaxial extensional flow 査読有り国際誌

Sugimoto M, Masubuchi Y, Takimoto J, Koyama K

MACROMOLECULES 34 巻 ( 17 ) 頁： 6056-6063 2001年8月

Melt rheology of ethylene ionomers blended with a small-molecule acid 査読有り国際誌

Nishioka A, Takahashi T, Masubuchi Y, Takimoto J, Koyama K

POLYMER 42 巻 ( 18 ) 頁： 7907-7910 2001年8月

Uniaxial elongational viscosity of PS/a small amount of UHMW-PS blends 査読有り国際誌

Minegishi A, Nishioka A, Takahashi T, Masubuchi Y, Takimoto J, Koyama K

RHEOLOGICA ACTA 40 巻 ( 4 ) 頁： 329-338 2001年7月

Thermal analysis of shear induced crystallization by the shear flow thermal rheometer: isothermal crystallization of polypropylene 査読有り国際誌

Masubuchi Y, Watanabe K, Nagatake W, Takimoto JI, Koyama K

POLYMER 42 巻 ( 11 ) 頁： 5023-5027 2001年5月

Molecular orientation and electrohydrodynamic flow in homogeneous ER fluids 査読有り国際誌

Iwatsuki H, Gohko N, Kimura H, Masubuchi Y, Takimoto JI, Koyama K

INTERNATIONAL JOURNAL OF MODERN PHYSICS B 15 巻 ( 6-7 ) 頁： 973-979 2001年3月

Domain structure and MR effect of ferrofluid emulsion 査読有り国際誌

Ogawa C, Masubuchi Y, Takimoto JI, Koyama K

INTERNATIONAL JOURNAL OF MODERN PHYSICS B 15 巻 ( 6-7 ) 頁： 859-863 2001年3月

The mechanism of ER effect induced by attaching flocked fabrics on electrodes 査読有り国際誌

Kato Y, Masubuchi Y, Takimoto JI, Koyama K

INTERNATIONAL JOURNAL OF MODERN PHYSICS B 15 巻 ( 6-7 ) 頁： 767-773 2001年3月

Electrically induced viscosity change in immiscible liquid blend 査読有り国際誌

Kimura H, Aikawa K, Masubuchi Y, Takimoto JI, Koyama K

INTERNATIONAL JOURNAL OF MODERN PHYSICS B 15 巻 ( 6-7 ) 頁： 1062-1069 2001年3月

Uniaxial elongational flow behaviour of SBS block copolymer melts treated at high temperature - The correlation of crosslinking and strain-hardening 査読有り国際誌 Open Access

Minegishi A, Takakashi T, Nishioka A, Masubuchi Y, Takimoto J, Koyama K

NIHON REOROJI GAKKAISHI 29 巻 ( 1 ) 頁： 61-62 2001年

Description of uniaxial, biaxial, and planar elongational viscosities of polystyrene melt by the K-BKZ model 査読有り国際誌

Nishioka A, Takahashi T, Masubuchi Y, Takimoto J, Koyama K

JOURNAL OF NON-NEWTONIAN FLUID MECHANICS 89 巻 ( 3 ) 頁： 287-301 2000年3月

Dependence of sonochemical luminescence on various sound fields 査読有り国際誌

Yanagida H, Masubuchi Y, Minagawa K, Takimoto J, Ogata T, Koyama K

ULTRASONICS 38 巻 ( 1-8 ) 頁： 671-675 2000年3月

Development of sheer flow thermal rheometer for direct measurement of crystallization fraction of polymer melts under shear deformation 査読有り国際誌

Nagatake W, Takahashi T, Masubuchi Y, Takimoto JI, Koyama K

POLYMER 41 巻 ( 2 ) 頁： 523-531 2000年1月

Development of shear flow thermal rheometer for direct measurement of crystallization fraction of polymer melts under shear deformation 査読有り国際誌

Nagatake W., Takahashi T., Masubuchi Y., Takimoto J., Koyama K.

Polymer 41 巻 ( 2 ) 頁： 523 - 531 2000年1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：Polymer

Recently viscoelastic measurement has received considerable attention as a complementary method to estimate the crystallization dynamics under shear. However, because of the complex relationship between the crystallization fraction and dynamic mechanical results, it has been difficult to obtain accurate crystallization fraction under shear. To conduct the direct determination of crystallization fraction under shear, the shear flow thermal rheometer (SFTR) having differential thermal analysis (DTA) has been successfully developed using a rotational shear rheometer. Two thermocouples to measure the reference and the sample temperatures were installed at each optimal position as DTA equipment. Two sheets of polyetheretherketone (PEEK) were put on two aluminum plates to prevent heat transfer between the sample and the aluminum plates for accurate measurement of DTA. The influences of using PEEK, instead of an aluminum plate and the thermocouple on rheology results were confirmed to be negligible. In the SFTR, shear strain was given from the lower plate. Both stress and differential temperature responses were simultaneously detected by the upper plate and thermocouples, respectively. The advantage of the SFTR over conventional rheometers was that the crystallinity fraction was able to be directly determined from DTA. In non-isothermal and isothermal preliminary experiments of iso-polypropylene, it was demonstrated that the SFTR provided two kinds of data by the simultaneous measurement of DTA and viscosity. The crystallinity fraction under shear was directly estimated from DTA in the SFTR.

DOI： 10.1016/S0032-3861(99)00226-8

低密度ポリエチレン溶融体の一軸，二軸，平面伸長粘度へのＫ‐ＢＫＺモデルの適応性査読有り

The shear-flow properties of electro-rheological liquid polymeric blends 査読有り国際共著国際誌

Riha P, Kimura H, Aikawa K, Masubuchi Y, Takimoto J, Koyama K

JOURNAL OF NON-NEWTONIAN FLUID MECHANICS 85 巻 ( 2-3 ) 頁： 249-256 1999年8月

Effect of chain structure on the melt rheology of modified polypropylene 査読有り国際誌

Sugimoto M, Tanaka T, Masubuchi Y, Takimoto J, Koyama K

JOURNAL OF APPLIED POLYMER SCIENCE 73 巻 ( 8 ) 頁： 1493-1500 1999年8月

Stress rectification in MR fluids under tilted magnetic field 査読有り国際誌

Takimoto J, Takeda H, Masubuchi Y, Koyama K

INTERNATIONAL JOURNAL OF MODERN PHYSICS B 13 巻 ( 14-16 ) 頁： 2028-2035 1999年6月

Electrically induced phase inversion in polyurethane/dimethylsiloxane blend 査読有り国際誌

Kimura H, Aikawa K, Masubuchi Y, Takimoto J, Koyama K, Uemura T

INTERNATIONAL JOURNAL OF MODERN PHYSICS B 13 巻 ( 14-16 ) 頁： 2011-2017 1999年6月

Preparation and property of model homogeneous ER fluids having urethane groups 査読有り国際誌

Minagawa K, Okamura H, Masuda S, Tanaka M, Gohko N, Masubuchi Y, Takimoto J, Koyama K, Uemura T

INTERNATIONAL JOURNAL OF MODERN PHYSICS B 13 巻 ( 14-16 ) 頁： 1998-2004 1999年6月

Effect of ultrasound frequency on sonochemical luminescence under well-determined sound pressure 査読有り国際誌

Yanagida H, Masubuchi Y, Minagawa K, Takimoto J, Koyama K

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 38 巻 ( 5B ) 頁： 3103-3104 1999年5月

A reaction kinetics model of water sonolysis in the presence of a spin-trap 査読有り国際誌

Yanagida H, Masubuchi Y, Minagawa K, Ogata T, Takimoto J, Koyama K

ULTRASONICS SONOCHEMISTRY 5 巻 ( 4 ) 頁： 133-139 1999年1月

Simulation Study on Effect of Polymer Entanglement on the Strain Hardening 査読有り国際誌

Y. Masubuchi, J. Takimoto and K. Koyama

Molecular Simulation 21 巻頁： 257-269 1999年

Melt strength and extrudate swell of high-melt-strength polypropylene 査読有り国際誌 Open Access

Sugimoto M, Masubuchi Y, Takimoto J, Koyama K

NIHON REOROJI GAKKAISHI 27 巻 ( 1 ) 頁： 67-68 1999年

A Brownian dynamics study of strain hardening of branching polymer melts 査読有り国際誌

Masubuchi Y, Takimoto J, Koyama K

SLOW DYNAMICS IN COMPLEX SYSTEMS 469 巻頁： 659-660 1999年

Electrorheological effect in liquid blends 査読有り国際誌

Kimura H, Aikawa K, Masubuchi Y, Takimoto J, Koyama K

SLOW DYNAMICS IN COMPLEX SYSTEMS 469 巻頁： 152-153 1999年

A systematic description by BKZ model of strain hardening or softening in uniaxial elongation of polymer melts 査読有り国際誌

Takahashi T, Nishioka A, Masubuchi Y, Takimoto J, Koyama K

JOURNAL OF MACROMOLECULAR SCIENCE-PHYSICS B38 巻 ( 3 ) 頁： 289-304 1999年

Strain-hardening property of polystyrene(PS) ultrahigh molecular weight(UHMW)-PS blends 査読有り国際誌

Minegishi A, Nishioka A, Takahashi T, Masubuchi Y, Takimoto J, Koyama K

SLOW DYNAMICS IN COMPLEX SYSTEMS 469 巻頁： 649-650 1999年

西岡昭博, 高橋辰宏, 増渕雄一, 滝本淳一, 小山清人

成形加工 11 巻 ( 6 ) 頁： 517 - 526 1999年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人プラスチック成形加工学会

Measurements of uniaxial, biaxial, and planar elongational viscosity and step stress relaxation of a low density polyethylene (LDPE) melt were carried out. The description of experimental uniaxial, biaxial, and planar elongational viscosities results by the Kaye-Bernstein-Kearsley-Zapas (K-BKZ) constitutive equation was examined. Three types of damping function forms, Wagner-Demarmels (WD) model, Papanastasiou-Scriven-Macosko (PSM) model, and Luo-Tanner (LT) model, have been proposed in the K-BKZ constitutive equation. These three damping function forms were examined to see which was able to describe the experimental shear, biaxial, and planar damping functions. The experimental shear and biaxial damping functions were described by the LT and PSM models better than the WD model, however, the experimental planar damping function was not described well by any of the three models. After estimating the best parameters in each model by fitting the three experimental damping functions, the uniaxial, biaxial, and planar elongational viscosity was calculated by the estimated parameters. The uniaxial elongational viscosity was predicted best by the LT model, then by the WD, and PSM models. For biaxial and planar elongational viscosity, none of the three models predicted well, thus the lack of suitability of the biaxial and planar elongational viscosity to the K-BKZ model was suggested.

DOI： 10.4325/seikeikakou.11.517

Systematic description by BKZ model of strain hardening or softening in uniaxial elongation of polymer melts 査読有り国際誌

Takahashi T., Nishioka A., Masubuchi Y., Takimoto J., Koyama K.

Journal of Macromolecular Science - Physics 38 巻 1999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：Journal of Macromolecular Science - Physics

Homogeneous polymer melts show strain hardening, while recent uniaxial elongational studies have revealed that some heterogeneous polymer melts show strain softening. A systematic description and explanation about strain hardening of homogeneous polymers and strain softening of heterogeneous polymers is still needed. Here, the Bernstein, Kearsley, and Zapas (BKZ) model is applied to give a systematic description using model relaxation spectra and model damping functions. The effects of damping function and the longest relaxation time on the strain hardening or softening are investigated in terms of intensity and critical strain. The intensity, that is, the degree of hardening or softening, is defined as the degree of positive or negative deviation from the Trouton rule. The critical strain is defined as the strain at which the deviation starts. The intensity is strongly affected by the damping function. If α, the damping parameter in the said damping function, is more than 2, strain hardening appears. With α less than 2, strain softening occurs. It is suggested that strain hardening or softening in various polymer melts is able to be characterized by showing the location of each polymer in the proposed figures. It is proposed that a systematic description in terms of the BKZ model is capable of explaining not only the strain hardening of homogeneous polymer melts, but also the strain softening of heterogeneous polymer melts.

Simulation Ssudy on Effect of Polymer Entanglement on the Strain Hardening 査読有り国際誌

Masubuchi Y., Takimoto J., Koyama K.

Molecular Simulation 21 巻 ( 5-6 ) 頁： 257 - 269 1999年

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Molecular Simulation

The effect of the molecular entanglement on the elongational viscosity was investigated by Brownian dynamics simulation in 2-dimension. The polymer was represented by freely-rotated bead-rod model. The entanglement constraint was assumed by a repulsive interaction between bonds in the chain and randomly located obstacles. Under an elongational flow, affine deformation was applied to spatial distribution of the obstacles. Varying lifetime and density of the obstacles, we investigated these effect on elongational viscosity. We found that (i) linear viscosity increases with increasing density while it is independent of the lifetime, that (ii) critical strain rate at which the strain hardening begins is independent of both the lifetime and the density, that (iii) the longer lifetime gives the stronger strain hardening, and that (iv) when the density becomes higher than entanglement threshold of the chain, the strain hardening is discontinuously enlarged. Brownian dynamics; polymer rheology; strain hardening; polymer entanglement; elongational flow; elongational viscosity.

DOI： 10.1080/08927029908022068

Measurement of biaxial elongational viscosity of polymer melts using lubricated squeezing flow method 査読有り Open Access

Nishioka A., Takagi Y., Takahashi T., Masubuchi Y., Takimoto J., Koyama K.

Zairyo/Journal of the Society of Materials Science, Japan 47 巻 ( 12 ) 頁： 1296 - 1300 1998年12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：Zairyo/Journal of the Society of Materials Science, Japan

Biaxial elongational rheometer using lubricated squeezing method has been installed. To start up the rheometer and to obtain reproducible and reliable data, the effects of experimental conditions on biaxial elongational viscosity data were investigated. Constant area method was preferable rather than constant volume method. It was concluded that the effects of the viscosity of silicone oil and the shape were neglisible when method of constant area was employed.

DOI： 10.2472/jsms.47.1296

充填系高分子溶融体の一軸伸長下での歪み硬化特性と内部変形査読有り

高橋辰宏, 中島広和, 増淵雄一, 滝本淳一, 小山清人

繊維学会誌 54 巻 ( 10 ) 頁： 538 - 543 1998年10月

Measurement of Young's modulus and Poisson's ratio of polymers under high pressure 招待有り査読有り国際誌

Masubuchi Y, Matsuoka H, Takimoto J, Koyama K, Ohta Y

4 巻 ( 3 ) 頁： 223-226 1998年9月

Stress relaxation of polymer melts in biaxial and planar elongations 査読有り国際誌

Nishioka A, Takahashi T, Masubuchi Y, Takimoto J, Koyama K

4 巻 ( 2 ) 頁： 121-123 1998年6月

'Positive' and 'negative' electro-rheological effect of liquid blends 査読有り国際誌

Kimura H, Aikawa K, Masubuchi Y, Takimoto J, Koyama K, Uemura T

76 巻 ( 1-3 ) 頁： 199-211 1998年4月

綿布の吸水性に対する圧力と仕上処理剤の影響査読有り

樋口才二, 鈴木淳, 久保田稔, 増渕雄一, 瀧本淳一, 小山清人

繊維学会誌 54 巻 ( 3 ) 頁： 152 - 158 1998年3月

Phase structure change and ER effect in liquid crystalline polymer/dimethylsiloxane blends 査読有り国際誌

Kimura H, Aikawa K, Masubuchi Y, Takimoto J, Koyama K, Minagawa K

37 巻 ( 1 ) 頁： 54-60 1998年2月

Processability of PS/Whisker composite in blow molding 査読有り国際誌

Nemoto T., Tsuji N., Kobayashi M., Yamada Y., Masubuchi Y., Takimoto J., Koyama K.

Technical Papers Regional Technical Conference Society of Plastics Engineers 頁： 557 - 563 1997年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：Technical Papers Regional Technical Conference Society of Plastics Engineers

Influence of the whisker contents of polystyrene on the parison formation were examined. It was found that i) for the parison formation, magnitude of the die swell decreased with the increasing of the volume fraction of the whisker and it corresponds to the strain hardening in the uniaxial elongation and that ii) on the other hand, magnitude of the draw dawn decreased with the increasing of the volume fraction of the whisker. It corresponds to the linear viscosity of the uniaxial elongation.