Journal of the Society of Rheology, Japan最新文献

{"title":"Shear-Induced Network Formation in Colloid/Polymer Mixtures: A Molecular Dynamics Study","authors":"T. Koga, Chen Li","doi":"10.1678/RHEOLOGY.42.123","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.42.123","url":null,"abstract":"It is well-known that rheological properties of latex dispersions are drastically changed by the addition of small amounts of polymers with associative interactions. This kind of technique has been widely used in application areas, especially in paints, coatings, and cosmetics. The associative polymers are also known as associative thickeners and rheology modifiers. In most cases, since large colloids with micrometer-size diameter strongly associate with polymers at quiescent states, the time-scale of the association and dissociation processes is quite long compared to the typical experimental time scale. Therefore, it is diffcult to observe the Newtonian regime in such systems. Recently, Otsubo and his collaborators studied rheological properties of mixtures of silica nanoparticles and poly(ethylene oxide) (PEO), and showed that the nonlinear steady shear viscosity exhibits Newtonian behavior in the small shear-rate region, and drastically increases with increasing shear rate, where the value of the viscosity is one order of magnitude larger than that in the Newtonian regime. This strong thickening is considered to be attributed to the shear-induced gelation. In the case of mixtures of telechelic associating polymers and colloids, one of the authors reported the study on rheological behavior by using a molecular dynamics (MD) simulation method. In the above-mentioned case, however, PEO chains have many hydrogen bonding sites along the chain, which associate with colloid particles. To understand the molecular mechanism of the rheological behavior of such nanocolloid/polymer mixtures, it is necessary to study the system of associating polymers with many associative groups along the chain. Therefore, in the present study, we perform MD simulations of mixtures of associating polymers with many associative groups and colloid particles.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81682635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Transient Network Structure in Sucrose Stearate/Water Systems","authors":"Saori Takahashi, I. Kaneda","doi":"10.1678/RHEOLOGY.42.103","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.42.103","url":null,"abstract":"slip through at the transient entanglement. 12) Because the mechanism of the mechanical relaxation of temporally entangled thread-like molecular assemblies is not well understood, further studies on a wide range of such materials are required. From the perspective of industrial application, the thread-like molecular assemblies are a promising candidate for novel drug delivery system on account of their relatively large hydrophobic space. 10) If we can engineer the system to have a stimuli response property, it could become a smart delivery The rheological properties of an industrial-grade sucrose stearate aqueous solution were studied. This solution at 1 to 8 wt % appeared translucent or turbid from 20 to 48 °C; however, it became transparent above 48 °C and its viscosity increased. Furthermore, the apparent viscosity of the sample solution increased with temperature, and showed peak value at 48 °C for all such samples. On the other hand, small angle laser-light scattering studies revealed that the molecular-assembly size of the surfactant abruptly decreased at the same temperature. The dynamic modulus of the sample at approximately 48 °C was successfully analyzed with a bimodal Maxwell model, which showed that sucrose stearate formed several types of molecular assemblies and the shape was dependent on temperature. In particular, the rheological properties at approximately 48 °C strongly suggest that the surfactant formed thread-like molecular assemblies.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83683607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fluctuating Junctions of Physically Cross-Linked Networks in a Single-Chain Model. – Consistency Between the Relaxation Modulus for Small Deformations and Green-Kubo Predictions","authors":"T. Indei","doi":"10.1678/RHEOLOGY.42.111","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.42.111","url":null,"abstract":"In theoretical attempts of predicting the viscoelastic behavior of polymer networks, such as chemical gels of rubbers, physical gels of associating polymers, and entangled polymer melts, the affine assumption is often employed to describe the junction (or node) motion of the networks under flows or deformations. That is, the motion of the junctions is assumed to obey the same deformation tensor as that used for the macroscopic deformation applied to the network surface. While the affine assumption captures the essential feature of the node dynamics somehow on average, neglect of the spatial (and temporal) fluctuations of junctions around the affine motion gives rise to several fundamental problems. One example is an overestimation of the plateau modulus for a given network topology when the affine assumption is employed. Also the viscoelastic relaxation spectrum depends on the extent of junction fluctuations. One way to implement the junction fluctuation into the theoretical model is to introduce the virtual spring that connects a point of the chain, which is supposed to be a member of a network junction, and the background field that is assumed to deform affinely. However, in singlechain models of polymer networks, the inclusion of the virtual spring brings about several fundamental problems. There have been some arguments about whether to include explicitly the stress σv originating from the virtual springs into the expression of the total stress σ of the network. Likhtman neglected σv in his slip-spring model for entangled polymer melts and assumed that the total stress σ is given by the stress from the chain σc alone because otherwise the contribution from the virtual springs is double counted. On the other hand, as Ramírez et al. noticed, the neglect of σv leads to a disagreement between the dynamic modulus of the chain part Gc(t ) obtained by applying a small external deformation to the network and that obtained from the Green-Kubo (GK) formula of the linear response theory Fluctuating Junctions of Physically Cross-Linked Networks in a Single-Chain Model. – Consistency Between the Relaxation Modulus for Small Deformations and Green-Kubo Predictions","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90356621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Slip at the Interface between Immiscible Polymer Melts II: Capillary Flow of Polymers with Unequal Viscosities","authors":"R. Komuro, S. K. Sukumaran, M. Sugimoto, Koyama Kiyohito","doi":"10.1678/RHEOLOGY.42.151","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.42.151","url":null,"abstract":"Quantitative investigations of polymer/polymer interfacial slip are typically performed using rheological and optical techniques. Almost all of the investigations that use only rheological data to determine the slip velocity at a polymer/ polymer interface are restricted to drag flows of multilayers where the parallel layers are stacked on top of each other and sandwiched between parallel plates. In these investigations, the polymer/polymer interfacial slip velocities were estimated using the reduction in the measured viscosity when compared to the viscosity estimated by assuming that slip at the interface between the polymers does not exist (“no-slip”). Assuming a stable, essentially flat interface, the no-slip viscosity of the parallel multilayers undergoing drag flow can be derived and is equal to the volume fraction weighted harmonic mean of the viscosities of the individual polymers. Crucially, the derivation of the no-slip viscosity relies on the fact that the stress distribution across the multilayer sample is uniform. While this estimate for the no-slip viscosity is appropriate for this flow geometry, devising such estimates for other flows relevant for polymer processing (such as pressure driven flows) is not straightforward. In particular, the harmonic mixing rule 4-6) cannot be applied to the case of coextrusion since the shear stress distribution is not spatially uniform within the multilayer sample. Owing to this methodological limitation, investigations of polymer/polymer interfacial slip during coextrusion of polymers with unequal shear rate dependent viscosities using only rheological data are few. Therefore, systematic quantitative investigations of the effect of molecular weight and temperature on polymer/polymer interfacial slip during coextrusion have thus far not been possible. In order to overcome the above mentioned difficulty, we recently proposed a novel approach to estimate the slip velocity at a polymer/polymer interface during pressuredriven two-phase coaxial flow. The approach uses an adaptation of the Mooney method, which is usually used to investigate slip of a polymer liquid at a solid wall. Henceforth, we will refer to this new approach as the “modified Mooney method”. Conceptually, the main advantage of the modified Mooney method is that estimations of the values of the physical variables (such as the viscosity) under the assumption of no-slip are not necessary. Hence, at least in principle, the method can be used to determine the slip velocity at a polymer/polymer interface for two-phase coresheath samples undergoing pressure-driven coaxial flow even when the viscosities of the two coextruded polymers are unequal. Whether this can be accomplished in practice is yet be determined. In our earlier work, we established the validity of the modified Mooney method by comparing its results to that obtained using the deviation from no-slip method. In order to facilitate the determination of the slip velocity using the de","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81518381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Controlling the Performance of Filled Rubbers","authors":"S. Kawahara, Yoshimasa Yamamoto, Yoshinobu Isono","doi":"10.1678/RHEOLOGY.42.79","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.42.79","url":null,"abstract":"The performance requirements for filled rubber greatly depend on the application (i.e., tires, engine mounts, belts, seismic isolation rubber, rubber rollers, etc.). Table I shows some examples. Thus, universal filled rubber, which possesses all the properties required for high performance products, is difficult to prepare, especially since some properties are antonymous. Additionally, the performance of filled rubber depends significantly on both the filler and filler aggregate structure. Consequently, high performance filled rubber is designed specifically for each product. Filled rubber is a composite material consisting of rubber and filler. In addition to selecting a suitable combination of rubber and filler, it is important to control the primary structure of the filler, the secondary structure of its aggregate, and its distribution. In particular, the appropriate processing conditions are indispensable to enhance the performance of filled rubber because the secondary structure of the aggregates and the distribution of the filler and/or its aggregates depend upon the structure of the filler and the processing conditions. Thus, precisely controlling the non-equilibrium structures of filled rubber governs performance. In this review article, methods to prepare high-performance filled rubber are described in terms of the relationship between the structure and properties of the filled rubber.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86262565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"弾性体中で亀裂が伸展する応力拡大係数範囲，K 0 ∼ K IC ，の推定","authors":"修己 上垣外","doi":"10.1678/RHEOLOGY.42.65","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.42.65","url":null,"abstract":"","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83822615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"UV Degradation Properties of a Virgin/Recycled Polymer Blend","authors":"Shigeru Yao, Aya Tominaga, H. Sekiguchi, Eiichi Takatori","doi":"10.1678/RHEOLOGY.42.61","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.42.61","url":null,"abstract":"We previously reported that the inner structures of thick (>3 mm) injection-molded test pieces of virgin polypropylene and recycled pre-consumer polypropylene were very different, even though their molecular and mechanical properties were almost the same. This difference was thought to be caused by the molding history of pre-consumer polypropylene. Due to this difference in their internal structures, thin films (<100 µm) of recycled pre-consumer polypropylene were very brittle. By examining the degradation properties of these thin films in response to UV irradiation, we found that the toughness of these samples decreased exponentially in a UV irradiation time-dependent manner. This dependence was almost the same in virgin and recycled samples, and we could superimpose of the results. We also found that the UV irradiation time-dependence was associated with the number of molecules that connected domains within the samples. In this study, we investigated the mechanical and UV irradiation time-dependent properties of thick samples composed of a blend of virgin and recycled pre-consumer materials. We found that the mechanical properties of these non-irradiated samples were almost the same. However, the mechanical properties of irradiated samples were significantly different. We also found that this difference linearly depends on the blend ratio. These results suggest that specimens containing recycled polymers can exhibit very poor durability even though there are no differences in their non-irradiated mechanical properties.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72731688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Preparation and Viscoelasticity of Hydrogen Bonded Supramolecular Ion Gels Composed of ABA Triblock Copolymer and C Homopolymer in an Ionic Liquid","authors":"S. Matsushima, Mikihiro Hayashi, H. Yamagishi, Atsushi Noro, Y. Matsushita","doi":"10.1678/RHEOLOGY.42.135","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.42.135","url":null,"abstract":"高分子材料への高機能・高性能化要求が高まる中で機能 性高分子が注目されている.その一つにソフトコンタクト レンズや防震材料などに利用されているポリマーゲル があ る.ここでポリマーゲルとは溶媒で膨潤させた高分子網目 2) のことであり,柔軟さを有しながらも流動性を示さないソフ ト材料 のことである.最近では平時は網目構造のために ゲル状(擬固体),熱や応力などの外場を加えた際には非共 有結合が解離して網目構造が崩壊するために液状(擬液体) となる超分子ポリマーゲル が多様な材料へ応用できると して大きな関心が寄せられている.しかしながら,有機溶 媒や水といった揮発性溶媒を含んだ超分子ポリマーゲルで は,加熱により溶媒が蒸発し同時にその可逆的な温度応答 性も失われてしまうという懸念があった.このような問題 に対応すべく最近我々は難燃・難揮発性のイオン液体 (IL) に注目し,これを水素結合性超分子ポリマーゲルの溶媒と して用いている.ILを溶媒として調製しているためこのよ うにして得られる超分子ポリマーゲルは超分子性のイオン ゲル,すなわち超分子イオンゲル とも呼ぶことができる. 我々はテレケリック型の水素結合性 ABAトリブロック共重 合体と,Aブロックと多点水素結合を形成する Cホモポリ マー (多官能性架橋剤)とを難燃,難揮発なイオン液体 中で溶解させることで,可逆的な温度応答挙動を示す水素 結合性超分子ポリマーゲルを調製し,広い温度範囲で取り 扱い可能な熱可逆性ゲルであることを明らかにしている. さらに多官能性架橋剤として振る舞う Cホモポリマーの添 加量を変化させたときの影響についても調査しているが , 添加量が比較的小さい場合に限られていた.そこで本研究 では多官能性架橋剤として振る舞う Cホモポリマーの添加 量を幅広い範囲で変化させて試料を調製し,添加量が大き い試料も含めて温度応答性を評価した. Preparation and Viscoelasticity of Hydrogen Bonded Supramolecular Ion Gels Composed of ABA Triblock Copolymer and C Homopolymer in an Ionic Liquid","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87843908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamics of Polar Low Mass Molecules Encapsulated in the ^|^#948;-cocrystal of Syndiotactic Polystyrene","authors":"Hideo Kobayashi, O. Urakawa, F. Kaneko, Tadashi Inoue","doi":"10.1678/RHEOLOGY.42.19","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.42.19","url":null,"abstract":"The δ -cocrystal of syndiotactic polystyrene (sPS) can capsulate various small guest molecules in the cavity of the crystalline region. We examined the rotational motion of isolated polar guest molecule, benzonitrile (BN), caged in the crystalline cavities by dielectric spectroscopy and the results were compared with the previously reported data of sPS / methyl ethyl ketone (MEK) system. The relaxation of BN in the crystalline region was specified from the comparison with the dielectric data of atactic-PS / BN system in which only the amorphous phase exists. The rotational relaxation time of BN in the crystalline cavity was 6 orders of magnitude longer, and the activation energy of BN was twice larger than those of MEK. These results suggest that spatial restriction due to the small cavity size strongly retards the rotational dynamics of the larger guest molecule, BN. Two-site model could successfully describe the temperature dependence of the dielectric intensity for sPS / BN system, revealing that there exist two stable states of BN molecules with energy difference of 7.42 kJmol - 1 in the crystalline cavity.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79907744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flow Behavior and Turbulent Drag Reduction of Viscoelastic Fluids","authors":"Shinji Tamano","doi":"10.1678/RHEOLOGY.41.289","DOIUrl":"https://doi.org/10.1678/RHEOLOGY.41.289","url":null,"abstract":"高分子水溶液や界面活性剤水溶液などに代表される粘弾 性流体の回転円板による容器内旋回流れにおいては,周方 向に向かって流れる主流ならびに遠心力と法線応力差によ る二次流れが存在する.粘弾性流体の二次流れはニュート ン流体のものに比べて複雑になることが知られていたが , 高レイノルズ数域における二次流れの非定常挙動について はほとんど明らかにされていなかった.実用上の回転円板 による粘弾性流体の容器内旋回流は,ビスカスカップリン グやビスカスヒータなどの流体摩擦を利用した機器におい て見られ,その非定常挙動の解明はこれらの機器の設計・開 発において重要であると考えられる.本研究では,高分子 水溶液や界面活性剤水溶液の非定常流れ挙動を明らかにす るために,従来の研究よりも高いレイノルズ数域において, 子午断面の二次流れの可視化観察,回転円板付近の流れの 3 次元可視化観察,ならびに回転円板面と平行な断面および 子午断面における PIV計測を行った.ここでは,高分子水 溶液および界面活性剤水溶液の非定常流れ場に関して,可 視化観察,LDV計測,および PIV計測により得られた代表 的な実験結果 を示す.さらに,粘弾性流体の回転円板に より誘起される容器内旋回流れの数値シミュレーション結 果 についても一例を示す.","PeriodicalId":17434,"journal":{"name":"Journal of the Society of Rheology, Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81318138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}