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Rheological model and numerical simulation of dispersive mixing of rubber compounds

100%

Petera J. , Clarke J.

Applied Mechanics and Engineering

1999

tom Vol. 4, no spec.

303-308

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.

The flow of viscoelastic fluids in an opposed jets rheometer and a Fano flow rheometer

84%

Wilkes C. , Gampert B.

International Journal of Applied Mechanics and Engineering

2003

tom Vol. 8, no spec.

319-324

The elongational rheometer used for this work is an opposed jet rheometer, which allows elongational flow measurements of highly dilute polymer solutions. The polymer concentrations can be lower than the critical concentration under steady state conditions and lower than the critical concentration in the case of flow conditions. A further experimental set up was used for characterising the viscoelastic fluids. The working method of this apparatus is the tubeless siphon or Fano flow, which can be understood approximately as the reverse fibre spinning process. The beginning of the fibre spinning process can be applied in order to determine the critical concentration . The experimental investigations undertaken here were carried out using a commercial, anionic polyacrylamide with a relatively high molar mass and hydrolysis factor. The polyacrylamide was dissolved in highly pure water. Sodium chloride with different concentrations was added to the solutions to control the partial neutralisation of negative charges at the ends of the polymer chains.