Investigation of the dependence of hexane-soluble fraction of polyethylene formed during slurry polymerization of ethylene with ziegler-natta catalyst

Abstract

The polymerization conditions affecting the amount of hexane-soluble fraction of polyethylene or low molecular weight polyethylene (LMWPE) which is the by-product of slurry polymerization process of ethylene with Ziegler-Natta catalyst have been investigated. The amount of LMWPE is in the range of 0.06-0.34 % by weight of high density polyethylene (HDPE) produced. The results show that agitator stirring speed, ratio of partial pressure of hydrogen to ethylene (H2/C2H4) and temperature have a great effect on the amount of LMWPE. The amount of co-catalyst (Al/Ti ratio) and polymerization time seem not to affect significantly on the amount of LMWPE produced. The observed activation energies of HDPE and LMWPE are 3.5 and 19.87 kcal/mole respectively. The amount of LMWPE produced is greatly affected by temperature, especially above 80 °c.