9 th International Seminar on Polymer Science and Technology Iran Polymer and Petrochemical Institute, Tehran, Iran 17-21 October 2009 Investigation of diene addition on ethylene–propylene (EP) copolymerization with a zirconocene catalyst S. Ahmadjo 1 , H. Arabi 1,* , M. Nekomanesh 1 , G.H. Zohuri* 2 , M.M. Mortazavi 1 , A. Farhadi 1 1. Department of Catalyst, Iran Polymer and Petrochemical Institute, P. O. Box: 14965/115, Tehran, Iran 2. Department of Chemistry, Ferdowsi University of Mashhad, Mashhad, Iran Abstract Metallocene catalyst of (Ind) 2 ZrCl 2 /MAO was synthesized and used in ethylene/propylene copolymerization and ethylene/propylene/diene terpolymerization. Methylaluminoxane (MAO) and triisobutylaluminum (TIBA) were used as cocatalyst and scavenger respectively. Activity of the catalyst was higher for the copolymerization of ethylene and propylene (EPR) than ethylene propylene and diene monomer terpolymeization (EPDM). The effect of [Al]/[Zr] ratio, temperature, and the ENB concentration on the polymerization behavior were studied. The highest productivity of the catalyst was obtained at 60 0 C and the [Al]/[Zr] ratio of 750:1 and 500:1 for EPR and EPDM production respectively. Keywords: Metallocene catalyst, terpolymerization, solution polymerization, EPDM * E- mail: , G.Zohuri@ippi.ac.ir Introduction In the past decades, metallocene catalysts have been the center of olefin polymerization and now their importance has increased as new catalysts to produce polymers with unique properties[1–5]. A well-known distinguishing feature of the single-site catalysts is their ability to copolymerize ethylene with α-olefins in a homogeneous fashion. Preparation of EPDM have been investigated using homogeneous metallocene catalysts[6-8]. The studies show that metallocene catalyst exhibited higher activities and higher incorporation rates of termonomers in the polymer without any noticeable side reactions[9-11]. Experimental Indene, Zirconium tetrachloride and Methyllithium were provided by Merck and used as received. All solvents were provided from Luba (India) dried and deoxygenated according to the methods taken from the literature[12]. MAO and 5-ethyldiene-2- norbornene (ENB) purchased from Aldrich. Ethylene and diene contents of the polymer were measured according to ASTM D3900-2002 and ASTM D6047-2002 standards respectively. Result and Discussion The bis(indenyl)zirconium dichloride catalyst was synthesized using a modified method of the literature [13]. The obtained solid was washed several times using dry ether (Et 2 O) to purify as much as possible following to drying. It was Copolymerization of ethylene and propylene (EPR) was carried out using the metallocene catalyst, while TIBA and MAO were used as a scavenger and cocatalyst respectively. Ethylene propylene (E/P) feed ratios of 80/20, 67/33, 50/50, 33/67 ml/ml, were employed into the copolymerization reactor. The activity of the catalyst decreased with decreasing E/P ratio. This behavior is common in the polymerization (Table I). Figure 1 shows the effect of [Al]/[Zr] molar ratio on the average rate of copolymerization, with increasing of the cocatalyst to about [Al]/[Zr]=750:1 increased the activity of the catalyst, however, higher concentration of the cocatalyst slightly decreased the activity. Terpolymerization of ethylene, propylene and the diene monomer (ENB), was carried out using the metallocene catalyst. The effect of [Al]/[Zr] molar ratio and polymerization temperature on the