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Tereza Moravkova, Petr Stern
Rheological and textural properties of cosmetic emulsions

Appl. Rheol. 21:3 (2011) 35200 (6 pages)

A set of 31 cosmetic emulsions, as the most frequent cosmetic dispersions, comprising lotions and creams (o/w, w/o), was analyzed by rheological procedures (RheoStress 300, Thermo Fischer Scientific) and by sensory profiling. The power law model was used for pseudoplastic body lotions and the Herschel-Bulkley model for viscoplastic creams to get basic rheological parameters (apparent viscosity, consistency parameter, yield stress value, plastic viscosity and flow behaviour index). The content of TiO2 in sun lotions probably caused better agreement with viscoplastic creams. Rheological analysis proved to be more suitable for the storage stability testing of the emulsion than sensory evaluation. Psychorheology was applied as a suitable complex method. Rheological parameters were compared to sensory texture attributes (removing from a package, ease of spreading, skin feel and thickness). Almost 60% of relationships among rheological and sensory parameters were statistically significant (P = 0.05). Considering relationships only between rheological and sensory characteristics (with each other), 46 % were statistically significant (P = 0.05). In the case of apparent viscosity and removing the lotion from a bottle the relationship was reliable enough (correlation coefficient 0.91) to estimate the sensory attribute by fast rheological measurement. The other statistically significant relationships (correlation coefficients proved that the sensory texture acceptability of a cosmetic emulsion could be partly predicted by rheological analysis.

Cite this publication as follows:
Moravkova T, Stern P: Rheological and textural properties of cosmetic emulsions, Appl. Rheol. 21 (2011) 35200.

Vaclav Mik, Jiri Myska, Zdenek Chara, Petr Stern
Durability of a Drag Reducing Solution

Appl. Rheol. 18:1 (2008) 12421 (6 pages)

Effectiveness of drag reduction by small addition of a surfactant in the turbulent flow of water depends on the structure and concentration of the additive, temperature of the solution and turbulence intensity, possible flow disturbance by a mechanical obstacle and the content of ions in water, but also on the age of the surfactant solution.We show how important aging effects are in connection with total surfactant concentration, in particular how rheological parameters of the drag reducing solution change with time.

Cite this publication as follows:
Mik V, Myska J, Chara Z, Stern P: Durability of a Drag Reducing Solution, Appl. Rheol. 18 (2008) 12421.

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