Delayed yielding of oil/water emulsions in presence of stabilizing biopolymer

摘要

This study investigates the stabilization of oil/water emulsions as a function of addition of a biopolymer (scleroglucan) which acts as an emulsion stabilizer. Rheological characterization in the form of controlled stress creep measurements has been carried out and it reveals the colloidal gel exhibiting a delayed yielding in a certain applied stress window. The delay time and stresses that an emulsion can withstand depend strongly on the concentration of added scleroglucan. Increasing polymer concentration, however, is limited to a maximum value, above which a limited effect on the delay time is observed. Investigating of the emulsion under study was visualized by means of cryo transmission electron microscopy which shows adsorption of scleroglucan onto the surface of the oil particles and a gel-like structure that connects the oil phases. The results mentioned in this study support that scleroglucan-surfactant interactions play a key role in the stabilization of the oil/water emulsion.