Determination of optimal combination of surfactants in creams using rheology measurements

The effect of surfactant on the rheological properties of some cream formul ations was studied. Two surfactants from two different series were combined to determine the combination which yielded the most viscoelastic structure for creams. The surfactants were the soybean derivatives soya sterol, poly ethylene glycol 10 soya sterol and polyethylene glycol 25 soya sterol and t he sorbitol derivatives sorbitan monooleate and sorbitan trioleate. The rhe ological properties of the creams were studied using oscillation stress swe ep, oscillation frequency sweep and viscosity tests. Droplet size distribut ion and conductivity of the creams were also determined. The combination po lyethylene glycol 10 soya sterol and sorbitan trioleate yielded the most vi scoelastic structure with linearly viscoelastic behaviour. (C) 2000 Elsevie r Science B.V. All rights reserved.