Stability and rheological behaviors of different oil/water emulsions stabilized by natural silk fibroin

In this study, oil/water emulsions stabilized by natural silk fibroin were prepared, and the effects of silk fibroin concentration ( φ SF ), oil volume fraction ( ϕ o ) and oil type on the stability and rheological behavior investigated. After creaming and reaching a stable state, the residual emulsion fraction increases with an increase in φ SF , ϕ o and oil polarity, while the size of emulsion droplets decreases with an increase in φ SF and oil polarity but a decrease in ϕ o . Due to the colloidal networks formed by the dispersed oil droplets, the emulsions show a predominantly elastic behavior with a frequency independent modulus and low phase angle. However, the droplet networks are not very strong, and a remarkable shear-thinning behavior occurs for all emulsions during steady shear flow. Moreover, stress overshoot also appears for some emulsions with low φ SF and polar oil during transient shear flows, due to the deformation of droplets before the breakage of their associates. The modulus, viscosity and yield stress become larger with the increase of φ SF , ϕ o and oil polarity, which is very beneficial for strengthening the creaming stability of the emulsions.