| POLYMERS Vol.65 No.3 |
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COVER STORY
Marriage Between Scattering and Rheology |
| COVER STORY: Introduction |
| Scattering Technique for Polymers | Takahiro SATO |
| <Abstract> The structure or conformation of the polymer chain is complex, and must be studied by many different kinds of experimental techniques, which give us information of global or local structure of the polymer chain. The scattering technique is one of such experimental methods, utilizing the interference of radiation waves scattered from many scattering points of polymer chains. Light scattering and small angle X-ray (or neutron) scattering are suitable to study global and local structures of the polymer chain, respectively. While the information from such scattering techniques is on the time-averaged structure of the polymer chain, rheological measurements provide the information of the polymer dynamics. Therefore, the scattering and rheology are complimentary techniques to study polymers, but it is rather difficult to measure both scattering and rheology in the same experimental condition. Dynamic light scattering may provide information same as that obtained from rheology. Keywords: Scattering Technique / Rheology / Polymer Conformation / Polymer Dynamics / Dynamic Light Scattering |
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| What is Rheology ? | Takanobu UEDA |
| <Abstract> Rheology is the study to examine the relationship of stress and strain and time. Rheology measurement device has become a convenient device that can be anyone in the IT progress. Rheology is the study to quantify the feeling that you touched, it can be seen anyone whether the result is correct. As a method to investigate the dispersibility of the dispersion in the rheology measurement, the flow curve linearity, the strain dispersion measurement linearity, the applicability of the Time-Temperature Superposition principle, the applicability of the Cox-Mertz rule, and large amplitude oscillatory shear is used. Keywords: Rheometer / Multi Frequency Wave / Dispersion / Flow Curves / Linearity / Cox-Mertz Rule / Time-Temperature Superposition Principle / LAOS |
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| COVER STORY: Highlight Reviews |
| Local Rheological Properties in Soft Materials | Atsuomi SHUNDO, Keiji TANAKA |
| <Abstract> Soft materials including polymers, micelles, gels and liquid crystals possess hierarchical structure with various length scales ranging from nanometer to micrometer. Thus, to give a better understanding of the dynamics, it is necessary to examine the structure and physical properties at various length scales, and clarify the correlation between them. Recently, measurements of local rheological properties in soft materials have become possible with the advent of various techniques, called microrheology. In this short review, we summarize recent studies of time- and spatial-resolved rheological measurements for soft materials, in particular a worm-like micelle solution and a hydrogel. Such studies provide information on a concentration fluctuation and a spatial heterogeneity of the systems. The combinational usage of microrheology and scattering experiments should be helpful for a better understanding of the dynamics in soft materials. Keywords: Soft Materials / Micelles / Gels / Heterogeneity / Microrheology |
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| Studies on Flow Induced Phase Transition by Using Scattering and Rheological Experiments | Yoshiaki TAKAHASHI |
| <Abstract> It is known that polymer liquids near the phase boundary sometime possess flow induced phase transition. Both scattering and rheological measurements are powerful experimental methods to study the phenomena. Outlines of studies on flow induced phase transition, based on the knowledge for one phase and two phase regions detected by scattering and rheometry, are briefly summarized. Keywords: Small Angle Neutron Scattering / Light Scattering / Shear Stress / First Normal Stress Difference / Elongated Domain Interface |
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| COVER STORY: Topics and Products |
| Scattering and Rheological Analyses of Nanoemulsion for Cosmetics | Takuji KUME |
| <Abstract> A stable nanoemulsion consisting of nanometer-sized oil droplets in water having a self-standing capability was prepared by high-pressure emulsification. Small-angle neutron scattering (SANS) clarified the presence of an ordered crystal-like lattice structure in addition to spherical domains with a diameter of about 30 nm. Rheological measurements showed that the nanoemulsion had a high viscosity and a yield stress. Nonfluidity of nanoemulsion is ascribed to crystal-like lattice structure of nanodroplets. A mixed solution of 2-hydroxyethyl cellulose and the nanoemulsion had shear-thickening behavior (shear-induced gelation). Real-time SANS measurements as a function of shear rate (Rheo-SANS) revealed that a possible mechanism of gelation was proposed from the viewpoint of shear-induced percolation transition. Furthermore, mixtures of the nanoemulsion and poly(acrylic acid) solutions were opaque and kept the same interdomain distance and high viscosity as the nanoemulsion. It was estimated that they had phase-separated structure between nanoemulsion phase and poly(acrylic acid) solution phase. Keywords: SANS / Rheology / Nanoemulsion / Lattice Structure / Shear-Induced Gelation / Shear Thickening / Phase Separation / Cosmetics |
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| Rheological Studies on Cosmetic Field | Ayano NAKAMURA |
| <Abstract> Texture of the cosmetic products is an important factor for the consumer satisfaction. It is considered that the texture is originated from various physical properties. However, since the phenomena are very complicated, to appropriate quantification is difficult. Our attempt is to quantify the texture of the initial touch of the cosmetics by studying the rheological properties. Flow properties of cosmetic lotions, containing various kinds of aqueous thickeners, were studied by creep measurement, and parameters were calculated from their rheological data based on the Nutting equation, which is an empirical equation. There were some correlations among the time dependency parameter and some sensory evaluation points, assessed by human panels. Simple linear regression analysis revealed that the evaluation scores of slimy feeling, sticky feeling, refresh feeling, and penetrating feeling of the cosmetic lotions were converted to numerical data by the parameter α. This quantification method for the texture of cosmetic products will be a useful tool for efficient development of cosmetic formulations. Keywords: Cosmetic Products / Aqueous Thickener / Microgel / Nutting Parameter / Texture / Sensory Evaluation Test |
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| Evaluation of Cellulosic Materials from the Marriage of Scattering and Rheology | Daisuke TATSUMI |
| <Abstract> Small-angle X-ray scattering (SAXS) and rheological measurements have been applied to the structural analysis of cellulose nanofiber suspension and cellulose gel. These mesurements cooperatively showed the fibrillation of cellulose fibers in the creation process of cellulose nanofibers. The network structure of optically anisotropic gel from cellulose solutions were also evaluated from these measurements. The density of contact points of cellulose chains in the gel evaluated from SAXS was coincident with that from rheological measurements. The marriage of scattering and rheology gives us happiness that we can see the structure and behavior of invisible particles and molecules. Keywords: Cellulose / Suspension / Solution / Scattering / Rheology / Structure / Gel / Network |
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| Polymer Science and I: A Personal Account |
| Quest for a New Research Field | Nobuhiro YANAI |
| <Abstract> I learned from my great supervisors about the importance to create a new research field. With a wish to find my own research field, I’ve been struggling in different research areas during my PD in the United States and after coming back to Japan. |
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| Polymer Science and I: A Personal Account |
| Rheology in The Human-Material Interface (Rheology on Cosmetics and Foods) | Isamu KANEDA |
| <Abstract> Physical proterty of foods and cosmetics is one of the most important characteristics that determins their commodity value. In this chapter, 3 topics on these fields are overviewed. C24HEUR makes a transient network structure, and it shows typical Maxell-body like behavior. Moreover, quite interestingly its relaxation speed is as same order as human motion. We have revealed that the network shows unusual mechanical response under deformation that exceeds its relaxation speed. We expected that such unusual exhibit a unique usage feeling when the polymer is applied in cosmetics. Mayonnaise is an amazing o/w emulsion. Recentry, a low-fat mayonnaise has been developed for good health. Although the steady state viscosity of such a low-fat mayonnaise seems simular to an ordinary mayonnaise, we have found out differences in a non-linear rheolical properties between these mayonnaises. Finally, the effect of edible emulsifier on the molten chocolate flow properties is reviewed. We developed a novel model chaocolate system that is employed spherical silica particles instead of suger cristal. It has been revealed that the emulsifier improved dispersibility of the silica particle in the model chocolate system. Keywords: Food / Cosmetics / Rheology / Usage Feelong / Texture |
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