Rheological Properties of Particle-Stabilized Emulsions

• Published in: Journal of dispersion science and technology 2010-05, Vol.31 (5), p.632-640
• Main Authors: Simon, Sébastien, Theiler, Stefan, Knudsen, Agnethe, Øye, Gisle, Sjöblom, Johan
• Format: Article
• Language: English
• Subjects: Atoms & subatomic particles; Chemistry; Colloidal state and disperse state; Emulsions. Microemulsions. Foams; Exact sciences and technology; Food science; Fumed silica; General and physical chemistry; particle-stabilized emulsions; pickering emulsions; Rheology
• ISSN: 0193-2691; 1532-2351
• DOI: 10.1080/01932690903218062

We have studied the rheological properties of fumed silica particle-stabilized emulsions. Two particles of different polarity were considered, the first more hydrophilic "Aerosil R7200," the second more hydrophobic "Aerosil R972." These particles flocculate and probably form a network at the investigated concentration. The flow curves of emulsions stabilized by a single type of particles exhibit yield stress, shear-thinning behavior and thixotropy. Moreover they display rheological features typical of gels. These features are attributed to strengthening of the particle network by droplets. Moreover the rheological properties of w/o emulsions stabilized by hydrophobic are similar to the ones of o/w emulsions stabilized by hydrophilic particles. The rheological properties of o/w emulsions stabilized by mixtures of hydrophilic and hydrophobic particles have then been studied by keeping the total particle concentration constant and varying the mass ratio between particles. The results show that when the hydrophobic particle concentration increases, the viscosity and stability of emulsions decrease establishing evidence that the network is weakened due to preferential orientation of hydrophobic particles towards the oil phase.