Effects of immobilization of methylalumoxane on cellulose support on ethylene polymerization behaviors.

Abstract

The way to improve the physical properties of polyethylene is done by adding nano-sized filler during the synthetic process. These can be commonly achieved by in situ polymerization. These studies are divided into two parts in this research. Firstly, it investigated the effect of types and amounts of cocatalyst and scavenger of zirconocene catalyst on ethylene polymerization behaviors. In fact, methylalumoxane (MAO) and triethylaluminum (TEA) were used as cocatalyst and scavenger, respectively. The ratios of [Al]MAO/[Zr]cat and [Al]TEA/[Zr]cat were varied during the in situ polymerization of ethylene. The polymerization was performed in a semi-batch autoclave reactor under adiabatic operation at 70 °C for 15 minutes. The best condition which reached the maximum catalytic activity was found at the ratio of [Al]MAO/[Zr]cat equals to 2000. For this reason, we used this condition in the next part. The second part focused on synthesis of polyethylene by in situ polymerization with different immobilization methods using cellulose-supported MAO/zirconocene catalyst. We performed the immobilization of cocatalyst/catalyst onto cellulose with three different methods including (i) immobilized cocatalyst/cellulose, (ii) immobilized catalyst/cellulose and (iii) immobilized catalyst/cocatalyst/cellulose. From the experimental results, it was found that the highest catalytic activity was obtained in PE-MAO/MCC because the MCC support with immobilization of MAO can stabilize the anion, which prevent termination.