Characteristic rheological properties of block copolymers related with flow-induced alignment of lamellae for diblock copolymers and effects of bridge, loop, and dangling end conformations of B component in ABA triblock copolymers are reviewed. In the flow-induced alignment phenomena, perpendicular alignment became dominant at high shear rates. Concentration and shear rate regions in which parallel alignment coexists become narrower when the viscosity ratio of components is close to 1. Relationship between elasticity and bridge, loop, dangling end fractions in B phase of sphere-forming ABA tribrock copolymers are examined by using series of model copolymer systems having almost the same microdomain structure but different bridge, loop, dangling end fractions. Elasticity was proportional to the bridge fraction and there was no practical difference between the effects of loop and dangling ends.
When a big earthquake occurs structure engineers proceed to the spot after the earthquake directly and diagnose suffering degree and will examine the right or wrong of the continuation use of the structure and repair or reinforcement method and need the considerable days till an examination result appears. Therefore the authors have developed the strain detective sensor using hard epoxy based paint for the purpose of anyone putting the sensor which could judge the soundness of the structure members to practical use in simple and easy cheapness after an earthquake than the conventional monitoring system. This sensor can detect the experienced strain based on crack patterns of the paint by observation, leading to drastically reduced cost compared with other sensors such as using strain gauges. In this study, we investigated strain-detection performance in case of the strain history by compression and tension. And the goal of this study was the quantification of the crack properties of the paint.
Local motion of synthetic polymers and gellan in dilute solutions was examined by a fluorescence depolarization method. Rheological measurements were also carried out for gellan aqueous solutions. The mean rotational relaxation time, a measure of the local chain mobility, for polystyrene in a good solvent was shorter than that in a poor solvent at all the molecular weights of polystyrene examined including the oligomer region. It was suggested that the local chain mobility was mainly determined by the local potential energy for the conformational transition of main chain bond. The local chain mobility of gellan was independent of the added salt concentration (cs), whereas the cs dependence of zero-shear viscosity indicated that the degree of chain expansion of gellan decreased with increasing cs.
To obtain reproducible, reliable data, the effects of experimental conditions on biaxial and planar elongational viscosities were investigated. It was clarified that a constant area method was preferable rather than a constant volume method. It was concluded that the effects of the viscosity of silicone oil as lubricant were negligible when the constant area method was employed. On the other hand, the effects of ion aggregates on zero shear viscosities η0 for ethylene-co-methacrylic ionomer melts were investigated. Rapid increasing of η0 for Zn ionomers was observed at high neutralization degrees, however, the rapid increase was not observed at all range of the degree neutralization in the case of Na ionomers. The formation of ion aggregates affects on damping functions in both cases of Na and Zn ionomers. This degree of neutralization well corresponds to the onset of strong strain dependence of h(γ) and increasing η0 for EMAA-Zn.
Flows of a viscoelastic fluid in slot die coating were experimentally and theoretically investigated. A viscoelastic fluid having a constant viscosity and a relaxation time (Boger fluid) as well as Newtonian fluid were used as test liquids in a wide range of Weissenberg numbers (0 < Wi < 42). We observed experimentally that the Boger fluid reduced the widthwise non-uniformity of the flow inside a slot die as flow rates were increased. However, this advantage disappeared in the higher flow rate region. This was not observed in the case of Newtonian fluids. In order to depict this behavior, a one-dimensional flow model was presented, where cavity flow and slot flow were combined by means of a planar entrance flow. The pressure drop induced by the planar entrance flow was assumed to characterize the flow from a cavity to a slot. Moreover, an excess pressure drop due to the viscoelasticity was empirically estimated, where the high deformation rates attained in the entrance flow from the cavity to the slot caused the increase of the excess pressure drop. The prediction by this model qualitatively agreed with the experimental results and showed utility of the proposed simple model.
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 α, β, and φ, were calculated from their rheological data based on the Nutting equation, which is an empirical equation. As another approach, sensory evaluation test of the cosmetic samples was carried out by human panels. There were some correlations among the time dependency parameter α 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. It is possible to estimate the texture of the products by studying the rheological value α.
Surfactant and polymer solutions are usually used under conditions involving transient dynamic surfaces, and therefore the dynamic surface tension (DST) is important in many industrial and biological fields. In a previous paper, we proposed a new mechanical model for surfactant solutions based on the concept that surfactant molecules rotate during the process of approaching the equilibrium surface state, which is different from the conventional adsorption theory, and a simple expression of DST was obtained as a function of the surface age. In the present paper, we discussed another model for polymer solutions, which is based on the similar concept that polymers rotate during the process of approaching the equilibrium surface state. As a result, a simple expression of DST for polymer solutions was derived as a function of the surface age. The expression was compared with our experimental data, as well as with results reported by other authors, and it was found that they are in good agreement. Furthermore, the characteristic time, which is the only unknown parameter in the model, was shown to be correlated with the weight concentration of the solution regardless of the type of solution examined.