Blow Molding Modeling: Pressure Rise and Die Swell Predictions-Edición Única

Abstract

In the present study a rheological analysis of the polymer melt history inside a concentric annular die of an extrusion blow-molding machine was studied using momentum and continuity balances for six high density polyethylene (HDPE) resins to determine the pressure rise and thickness swell. It also tried to develop a laboratory technique to predict die swell during blow molding. The rheological measurements included oscillatory behavior, relaxation modulus, steady state behavior, and capillary flow. They were used to generate material functions that were compared to predictions from the Wagner constitutive model and to blow molding processability data. A modified damping function was developed and used in the prediction of steady state elongational viscosity.