Thesis (M.Eng.)--Chulalongkorn University, 2012

At present, polyethylene has been widely used in the industry of manufacturing plastic bags. In the production of polyethylene, Ziegler-Natta catalysts and metallocene catalysts are able to producing polyethylene. Metallocene used in associate with methylaluminoxane shows very high activity in polyethylene polymerization. For metallocene catalysts used in the industry, it has developed and improved supported metallocene because it enables their use in gas- and slurry-phase processes and prevent reactor-fouling problems. Unfortunately, owing to the supporting effect, it is found that the catalytic activity of catalysts in the heterogeneous system is usually lower than the homogeneous one. In the past, it has been studied to modification on support. The results showed that the modification on support exhibited a promising enhancement for activity in metallocene catalyst systems. The study was divided into two parts. In the first part, study on synthesis of polyethylene using coir dust and cellulose as support was investigated. Two variables in this part are types of support and filler loading in polyethylene composites (10, 20, 30, and 40 %wt). It was found that the catalytic activity of coir dust was lower than the cellulose system. Catalytic activities can be decreased with increasing amount of coir dust while the activities increase with increasing cellulose loading. The addition of 30 % of cellulose shows that the maximal activity. In the second part, cellulose supports modified with B and Ga were employed in ethylene/1-hexene. It was found that the Ga-modified cellulose gave the higher activity than that of the non-modified one. The polymerization activities obtained from cellulose-Ga-2% exhibited the highest activity among the cellulose having Ga modification. Conversely, the B-modified cellulose gave lower activity than that of the non-modified one. All the obtained polymers and copolymers were characterized by SEM and DSC to determine the polymer properties.