| Abstrakt: |
All polymerization experiments were carried out in a Büchi glass reactor capable of operating at propylene pressures of 1‐7 atmospheres. Two types of MgCl2supported catalysts with controlled morphology were studied, viz., catalyst systems containing either a 1,3 diether (Catalysts A and D), 9,9‐bis (methoxymethyl) fluorene, or a simple diester (Catalysts B, C and E) such as diisobutylphthalate, used as reference systems. The kinetic behaviours of these catalysts were investigated for propylene polymerization. The 1,3‐diether based systems proved to be excellent catalyst systems for propylene polymerization showing high polymerization activities and stable rate‐time profiles and produced spherical polymer particles. Catalyst pre‐treatment was found to play an important role in controlling the morphology of the final polymer. A tritiated alcohol radio‐quenching technique was used to determine the concentrations active centres: values of 7.5 and 5.1 mol/mol % respectively were obtained for catalysts A and D and 3.5, 2.9 and 2.2 mol/mol % respectively were obtained for catalysts B, C and E. Catalysts A and D showed very high polymerization activities and also higher C0* values. All polymers produced were characterized by SEM, DSC, extraction and molecular weight determinations. |
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