Thesis (M.Eng)--Chulalongkorn University, 2011

This research aims to investigate the effect of Lewis acids on the synthesized Ziegler-Natta (ZN) catalyst (MgCl2+Lewis acid/DEAC/TiCl4) for ethylene polymerization with various ratios of AlCl3 and ZnCl2 as the Lewis acids employed. The catalysts were characterized by ESR, SEM-EDX, ICP, and XRD. From the ICP analysis, it was found that the titanium content in catalyst decreased with increasing the amount of Lewis acid compared with in the absence of Lewis acid system. However, the result obtained from SEM-EDX showed that titanium content at surface of catalyst increased with increasing amounts of Lewis acid resulting in better catalytic activity due to most of reaction also occurred at the surface of catalyst. Moreover, the molecular weight distribution obtained from the GPC result apparently increased because the Lewis acid can be a part of catalyst leading to increased number of active centers.