EFFECT OF TEMPERATURE ON THE FLOW BEHAVIOR OF POLYSTYRENE LATEX-GELATIN DISPERSIONS

In industry, the theology of photographic color coupler dispersions is found to alter with temperature during processing and film coating. T he reason for the change in the theological properties with temperatur e is poorly understood. The color coupler dispersion is found to be so complex that the prediction of rheological behavior from first princi ples is extremely difficult. To understand this behavior, dispersions of polystyrene lattices have been used because of the well-defined, we ll-characterized, and easy to control properties of these particles. T he steady shear viscosity of the model dispersions (polystyrene lattic es) has been measured as a function of shear stress, temperature (25-9 0 degrees C), particle size, and concentrations of gelatin, NaCl, and surfactant. The effect of temperature on the dispersion medium has bee n found to follow the Arrhenius equation in the temperature ranges 40- 90 degrees C. The theological behavior of the latex-gelatin dispersion s in this study has been explained in terms of hydrodynamic interactio ns between particles as well as nonhydrodynamic interactions such as v an der Waals, electrostatic, steric, and Brownian forces. (C) 1995 Aca demic Press, Inc.