The goal of the thesis will be to investigate the effect of surfactants on the rheological properties of capillary nanosuspensions such as yield stress, viscosity, storage and loss moduli, G‘ and G“. The surfactants can influence the nanosuspension rheology (at least) in three ways: (i) by lowering the interfacial tension; (ii) by increasing the elasticity of the oil/water interface, and (iii) by affecting the three-phase contact angle particle/ water/ oil. These effects will be investigated experimentally and interpreted theoretically by development of a model and computational procedure.
– The effect of water- and oil-soluble surfactants on the rheology of capillary nanosuspensions with aqueous and oily capillary bridges will be investigated at surfactant concentrations below and above the critical micellization concentration;
– For the used systems, the oil/water interfacial tension and dilatational elasticity, as well as the three-phase contact angle will be determined by means of appropriate experimental methods;
– Theoretical model and computational procedure for analysis of the state of capillary nanosuspension and its rheology will be developed; the quantitative interpretation of the experimental data will allow prediction and control of the nanosuspension rheology.
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