Influence of the concentration of a gelling agent and the type of surfactant on the rheological characteristics of oleogels

Abstract

The investigation on the influence of components that contribute diverse degrees of viscosity to the formulations is of great interest in medicines for topical use. It is such the case of a derivative of the cellulose—ethylcellulose—that participates in the formula of the oleogels of olive oil as a gelificant agent. Surfactant agents—Olivem—can also modify the rheological characteristics of oil gels. In this work, it is studied how the variation of the concentration of ethylcellulose (3–5%) notably changes the viscosity of the prepared ones. The most concentrated preparations in gelling agent are the most viscous and also present a plastic material, whereas the minor concentration awards a Newtonian character to the prepared ones. On the other hand, the influence of the temperature has been investigated—25 and 37 °C—verifying that the viscosity of the samples diminishes with the increase of temperature. The influence of the addition of surfactant products—Olivem 900, 700 and 300—has given a result that prepared with major viscosity are those which include Olivem 900 that can be qualified like plastic. The most fluid prepared are those which have been elaborated with Olivem 300, and their liquid character has been confirmed by rheological measurements—viscometry, oscillometry and creep-recovery. Many applications can be foreseen in pharmaceutical as well as in the cosmetic area where the use of natural vegetable oils as vehicles for drugs is large.