A COMPARISON OF ELECTRICAL AND RHEOLOGICAL TECHNIQUES FOR THE CHARACTERIZATION OF CREAMS

Two complex semi-solid emulsion systems, one ionic and one non-ionic, have been evaluated using both conventional (conductivity measurements and continuous flow rheology) and oscillatory (dielectric spectroscop y and oscillatory rheology) methods. The results of specific conductiv ity measurements indicated differences in charge mobility, with the io nic cream showing a considerable higher conductivity (171.0 mu S/cm co mpared to 9.3 mu S/cm for the non-ionic system). Dielectric spectrosco py allowed a more sophisticated electrical analysis to be obtained, an d a discussion is given of how the data relates to the current model f or interpreting the low frequency response. Flow and oscillatory resul ts indicated that greater internal structuring, leading to higher elas ticity, was achieved for the ionic system. It is demonstrated that bot h techniques yield different yet complimentary information on the crea m structure. The study has indicated that the use of dielectric spectr oscopy and oscillatory rheometry, in addition to conventional methods, may lead to a better understanding of the emulsion microstructure.