Simplified shear relaxation modulus function of HDPE for FE simulation in extrusion blowing process

Attempts to apply finite element analysis for simulation of the final geometry from extrusion blowing process have been studied. One of the accuracies for the prediction is a suitable mathematical model of the thermoplastic during the process. Visco-elastic model is found to be a suitable model by many researchers. This paper simplified the shear relaxation modulus function (SRMF) which characterizes the high-density polyethylene in molten state. Instead of the series of five exponential functions previously used, our simplified-SRMF consists of one power function of temperature and time. The deviation of our model from Williams-Landel-Ferry model with KBKZ constants, between the temperature of 140°C to 200°C and time from 0 to 10 sec, is 9.3706%. When simulated on a bottle, our model has the final bottle thickness and time deviation from WLF-KBKZ model by 0.19622% and 3.07362% respectively