Rheological model and numerical simulation of dispersive mixing of rubber compounds

With the ultimate aim of improving mixer geometry by using a mathematical model for rubber mixing, this Paper concentrates on the dispersive mixing process of filler disagglomeration. Specially designed elongational flow experiments were used to achieve dispersive mixing under conditions of known stress and strain rate history. It was found that the disagglomeration process is satisfactorily described by a first order differential equation with the rate constant proportional to the power density experienced by the compound during mixing. The kinetic model was implemented in original finite element software to obtain a 2-dimensional simulation of mixing in a twin rotor internal mixer. It was concluded that the 2-dimensional simulation would be useful for relating cross-sectional rotor geometry to efficiency of filler disagglomeration, and hence dispersive mixing.