When aqueous solutions of five oligosaccharides and one polyol compound were applied to the skin, tactile intensity and temporal changes, as defined by five Japanese onomatopoeic words, were observed. Moreover, the relationships between the sensations and the physical and chemical properties were investigated.
No difference in the tactile characteristics was observed among the samples during application; however, there was a difference in the characteristics among samples in the sensations of “beta-beta (sticky)”, “gishi-gishi (squeaky)”, and “sarasara (smooth)” after application. In terms of temporal changes, the sensations of oligosaccharides were first described as “nuru-nuru (slimy)”, which then changed to “gishi-gishi (squeaky)” and later to “beta-beta (sticky)”, “shittori (moist)”, and “sara-sara (smooth)”. Among the samples, a difference was observed in the timing of feeling “beta-beta (sticky)”, “shittori (moist)”, and “sara-sara (smooth)”.
The correlation between the “beta-beta (sticky)” feeling, which is a contextually undesirable quality of oligosaccharides, and the physical and chemical properties was determined. A high correlation was observed among adhesiveness, integral value of the application force for the final 20 s of application, and solubility. It was considered that the sticky oligosaccharides have these physical properties that were highly correlated described above.

We investigated the thickness of the skin layer just below the surface of the glossy part and cloudy part of tiger-striped flow marks that appeared in injection moldings of polypropylene (PP)/talc compounds, and we examined the correlation between flow marks with the same-phase (SP)-type pattern and “flow front slip” inferred in our previous paper. The cycle of gloss change on the surface of injection moldings of PP/talc materials showing one SP-type and two different-phase (DP)-type flow marks was the same as the cycle of skin layer thickness change, regardless of the flow mark pattern. In both the patterns, the thickness of the skin layer was minimal in the glossy area and maximal in the cloudy area. Furthermore, the minimum and maximum values of the skin layer thickness in the SP type were smaller compared with the DP type. Regardless of the unstable flow mechanisms of the flow front, the glossy part and the cloudy part were generated due to the time lag when the molten resin contacted the mold, after which the flow marks were generated. The SP-type flow marks that appear in the PP/talc compounds used in this study can be attributed to flow front slip.

In this study, we investigated the influence of compatibility between the particle and the dispersant on the rheological property using condensed suspensions with different dispersants (epoxy or amine). In the general flow-curve, the samples have not difference. In the solid regime below the yield stress, the amine-based sample with good compatibility has the flow history as the increases of viscosity in the decrease segment on the hysteresis loop test. In the fluid regime of middle strain range, the thickening and hardening happens at the time of the reversal rotation on the amine-based sample. It is found that the good compatibility influences the wide strain range from the solid regime to the fluid regime as the flow history.

Water-soluble polymer comes to be used for O/W type cosmetics from a viewpoint of skin irritation, feeling and long-lasting effect. A development of a polymer emulsifier also came to be performed in recent years. The emulsion stabilizing ability of polymer is derived from not only interfacial stabilization but also the structure modification of continuous phase. Therefore, rheological measurements of aqueous solutions of polymer and emulsions were performed, and the emulsification mechanisms were considered. Rheological properties of an emulsion using polymer thickener are dominated by properties of aqueous solution of the polymer. Polymers forming solid state at static state are preferable for the formation of O/W type emulsions.

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.