The Influence of Various Silicones on the Rheological Parameters of AZG Containing Silicone-Based Gels

Aluminium zirconium tetrachlorohydrex glycine (azg) is a popular antiperspirant!deodorant agent , formulated in various forms including the clear gels . silicones are used forthe preparation of these gels, giving them desirable characteristics. the aim of this study wasto investigate the influence of various silicones, when used in combination, on the rheologicalproperties of the resulting azg gels prepared. based on preliminary studies, various azgcontaining silicone-based gel formulations were prepared. silicones used (as ternary mixtures)included abil® em 97, abll® 8839 and abll® 8852. formulations prepared were thenexamined rheologicajly and their plastic viscosity and yield values determined. results showedthat the amount of able) em 97 (used as an emulsifier) present within the gel formulationis critical. an increase in the amount of this silicone, corresponding to a small decrease in theamount of the hydrophobic structure building (gelling agent) abll® b8839, increased theplastic viscosity and yield values of the gel. on the other hand, an excess amount of abil®b8852, as a hydrophilic co-surfactant, reduced the viscosity and yield values of the resultinggel. eventually, among the formulations prepared, formulation f5 with suitable aesthetic andskin feel properties, spreadability and rheological behaviors, was selected for further studies.by constructing the up-curve and down-curve of this formulation, presence of a plasticthixotropic behavior was confirmed. inclusion of various amounts of the hydrophobic siliconebasedagent , dimethicone, within formulation f5 showed that by increasing the amount ofdimethicone present, the plastic viscosity and yield values of the gel would be reduced .this reduction was significant at dimethicone concentrations above 0.5%. furthermore,by increasing the amount of dimethi cone present, the calculated percentage of reductionin plastic viscosity also increased . this means that the extent of thixotropicity of the gelformulation increases by the addition of dimethicone. this finding was also backed up by theresulting rheograms constructed. overall, addition of 0.75% dimethicone produced the mostacceptable product in terms of an appropriate viscosity, yield value and extent ofthixotropicity.in conclusion, this study shows that in-depth rheological assessment of azg gels preparedfrom silicones could be used as an important tool during their formulation and characterizationin order to obtain an effective formulation with desirable properties.