Thesis (M.Sc.)--Chulalongkorn University, 2015

The aim of this research is to study the effect of different Ziegler-Natta catalyst preparation methods on ethylene polymerization in the presence of comonomers. Two different Ziegler-Natta catalysts, prepared by addition of AlCl3 via chemical treatment (Cat.A), and physical blending (Cat.B), were used and compared with one without AlCl3 (Cat.C). The prepared catalysts were characterized by SEM, XRD, PSD, and elemental analysis. It was found that Cat.A was uniformly spherical-like particles while Cat.B and Cat.C had irregular shape. Particle size distribution of Cat.A was narrower than Cat.B and Cat.C. At the given Al content of catalyst, catalytic activity of individual polymerization process and comonomer incorporation was determined. Five comonomers, i.e., 1-butene, 1-hexene, 1-octene, 1-decene, and 1-dodecene were selected for this study. The obtained polymers from these three catalysts were characterized by melt flow index tester, density gradient tube, DSC, and GPC-IR. The results showed that when the concentration of comonomer increased, the density of the polymers using Cat.A was lower than Cat.B and Cat.C for both type and quantity of comonomers. The bulk CH3/1000C (short chain branching used for measurement of comonomer incorporation) of the polymers was higher when the amount of comonomer increased. In addition, the bulk CH3/1000C of the polymers using Cat.A was higher than Cat.B for every type and quantity of comonomers. It can be concluded that Ziegler-Natta catalyst prepared via chemical treatment provided the polymers with higher comonomer incorporation than by physical blending.