ASME International Mechanical Engineering Congress and Exposition (IMECE), Colorado, United States Of America, 11 - 17 November 2011, pp.263-269
Coextrusion heads are widely used to produce multi-layered products such as pipes and vessels in plastics industry. Spiral mandrel dies which are used in coextrusion heads provide good thickness uniformity with a broad range of processing parameters (raw material, throughput, temperature), short residence times (material or colour changes), low pressure drop and good thermal control. In the present study, the effects of operating conditions such as production rate and temperature on the pressure drop through the spiral mandrel die and the occurence of melt fracture are investigated by Computational Fluid Dynamics (CFD) simulations. The temperature dependent viscosity versus shear rate data for grade QB79P (Carmel Tech) polypropylene (PP) melt under study are measured by use of an Anton-Paar Physica MCR 301 model rotational rheometer with a 25 mm diameter parallel plate geometry and a capillary rheometer using capillary dies of various lengths with 1 mm diameter hole .