Comparative Study for Melt Flow Index of High Density Polyethylene, Low Density Polyethylene and Linear Low Density Polyethylene

Abstract

This study focus on the rheological behaviour of polyethylene polymer. The effect of molecular weight for three different types of polyethylene were study; high density polyethylene (HDPE), linear low density polyethylene (LLDPE) and low density polyethylene (LDPE). To find the rheological behaviour of the polymer, melt flow indexer and capillary rheometer was used. The shear stress and shear viscosity obtained from these three different polyethylene polymers were compared with the shear rate. It was observed that with the increase in shear rate, shear stress also increases. The behaviour of viscosity for HDPE, LLDPE and LDPE also discussed at the varying amount of shear rate. It was also found that viscosity of HDPE, LLDPE and LDPE decreases with increasing shear rate. The value of log shear stress of HDPE increases with an increase in log shear rate. The value of extension viscosity decreases from 8.295 to 1.606 KPa.s with a very high increase in extension rate of 23.5 s^-1 to 721 s^-1. Molecular mass and its distribution have a significant effect on the rheological behaviour of polymers.