Computational modelling of the separation of molten polymer blends by a centrifugal technique

Computational modelling of a centrifugal technique for separating binary mixtures of thermoplastic polymers in the molten state is presented. The technique may be useful for the recycling of polymeric materials. The study investigates the physical process of component separation due to the centrifugal force in a batch process, showing the potential of using a dispersed model for describing the complex mechanism underlying the technique. Given the long time scales of change of the flow field, the polymer melts are modelled as inelastic, shear-thinning materials. The centrifugal force drives the component with the higher density to the outer region of an annular cross section occupied by the melt inside a rotating containment. The model system PET/LDPE is investigated in detail. The simulations allow to predict the process time needed for the separation. The simulations are the basis for studying a continuous process in a rotating tube.