Preparation of Ultra High Molecular Weight Polyethylene Using Bi-supported SiO2/MgCl2 (spherical)/TiCl4 Catalyst: A Morphological Study

作者：Zohuri Gholamhossein^*; Bonakdar Mahbobeh Ahmadi; Damavandi Saman; Eftekhar Melika; Askari Mahdieh; Ahmadjo Saeid

来源：Iranian Polymer Journal, 2009, 18(7): 593-600.

• polyethylene
• ultra high molecular weight
• Ziegler-Natta catalyst
• bi-supported catalyst
• morphology

Polyethylene with a viscosity average molecular weight ((M) over bar (v)) as high as 3.42 x 10(6) was synthesized. The (M) over bar (v) increased with monomer pressure, while higher polymerization temperature decreased the molecular weight of the resulting polymer. The method of polymerization involved slurry using morphologically improved bi-supported catalyst of spherical SiO2/MgCl2/TiCl4. Triethylaluminium (TEA) was used as a cocatalyst, and hydrogen served as the chain transfer agent. The crystallinity of the obtained polymer was between 50% and 60%, indicating semicrystalline polyethylene. Morphological study reveals that the main damage suffered by the catalyst particles was due to chemical interactions with the cocatalyst at the early stages of the polymerization. The rate/time profile of the polymerization decayed with the highest activity at the beginning of the polymerization. The behaviour also affected the morphology of the polymer particles which could be due to the sudden fragmentation that resulted from fast-growing polymer particles. The optimal activity was obtained at [Al]:[Ti] = 770:1 molar ratio at 60 degrees C. The polymerization was first order with respect to the monomer concentration. Polymerization activity was stable between 55 degrees C and 70 degrees C.

• 出版日期2009-7