Date of Award

2008

Thesis Type

Masters

Document Type

Dissertation

Divisions

Faculty of Science

Department

Department of Chemistry

Institution

Universiti Malaya

Abstract

The influence of different dispersing agent on the rheological behaviors of paraffin oil-water emulsion with addition of TiO2 for uv-protect and moisturizing active ingredient was studied. While making creams with minimal structural defects and longer storage stability, it is important that preparation conditions be optimized. Settle volume properties, Zeta potential, effective diameter and settle volume of TiO2 suspension were studied in the presence of glycolipid (DDM and Carrageenan), nonionic (PEG 10,000 and Brij 35P) as well as anionic surfactants (sodium dodecyl sulfate, SDS). In the experiments, the higher concentration of dispersing agents shows higher settle volume percentage, higher zeta potential and gives a smaller average size of particles distribution in the TiO2 solution. The results obtained show significant influence of the type of surfactants on the measured quantities. Among the dispersing agents studied, l-Carragenan was proven to be most effective dispersing agent followed by DDM, SDS, PEG 10,000, and Brij 35P. It could be due to the existence of anionic sulfate groups, l-Carrageenan can interact strongly with oppositely charged cationic by ionic interaction. The systems investigated also reports structure and viscoelastic property of dispersing agents stabilized o/w emulsions, and they tend to show higher shear viscosity (η) at whatever given shear rate (. g) during steady rotational shear measurement and appeared superior of storage modulus (G') and loss modulus (G'' ) value throughout all measured in oscillatory shear test, in contrast to by DDM, SDS, PEG 10,000, and Brij 35P stabilized emulsion. These l-Carragenan stabilized emulsions also exhibited a higher degree of shear thinning behavior and results in a higher magnitude of yield stress ( y s ),which means better stabilized and have a good storage stability compared to DDM, SDS, PEG 10,000, and Brij 35P stabilized o/w emulsions.

Initial

khm

Additional Information

Dissertation (M.A.) – Faculty of Science, Universiti Malaya, 2010.

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