A New Approach to the Optimization of Blends Composition in Injection Moulding of Recycled Polymers

The use of recycled polymers is widespread for the injection moulding of many commodity plastic parts. Recycled polymers are usually blended with virgin polymers to obtain the best trade-off between cost and low melt viscosity. This last constraint is necessary to avoid short shots and to minimize the clamp force of the required injection moulding machine and, therefore, the process cost. The current industrial approach to this problem is to select the polymer blend by trial and error. In this paper a new approach to the minimisation of the overall manufacturing cost is proposed. It is based on a rheological model of the blend which has been developed from experimental tests according to the mixture design technique. The approach has been validated through an industrial case study.