Dynamics simulation of disperse systems in the presence of a structure-related mechanical barrier resulting from surfactant adsorption

Resumo

A computer model has been developed to refine the notions of the kinetics of structural transformations in surfactant-modified disperse systems, the mechanism of the influence of adsorption layers on viscosity, conditions of aggregation, and evolution of nonuniformities in microstructures. Classical concepts of the structure-related mechanical barrier providing disperse systems with stability to aggregation, as well as the criterion of adsorption-layer breakdown upon interparticle collisions under dynamic conditions, have been used. It has been shown that adsorption-layer breakdown under dynamic conditions may lead to the appearance of an extreme in the viscosity curve of a disperse system. The combined effect of additives of surfactants with different molecular masses successively added to the systems has been studied via taking into account the influence of surfactant adsorption layers on the dynamics of contact interactions. The simulation results make it possible to optimize the regulation of structure-related rheological properties of dispersions so as to decrease their apparent viscosity with a simultaneous increase in the uniformity of the structure.