Silica supported metallocene/MAO-systems: comparison of the polypropylene growth during bulk phase polymerization with slurry phase experiments

In situ formation of nanocomposites based on polyethylene and silica nanospheres

“…However, it is important to mention that the increase in molecular weight could also be due to free trimethylaluminum in the MAO which has been reported to prevent the bimolecular deactivation of metallocene catalysts 30. The polydispersity (PDI) of ∼ 2 for the polymers obtained are typical of metallocene catalysts because they are single site catalysts and have identical active centers 31. Some authors19, 20, 24, 32, have reported that when metallocene catalysts are supported on silica for ethylene polymerization the catalytic activity decreased in comparison with homogeneous systems.…”

Reaction Calorimetric Approach to the Kinetic Investigation of the Propylene Bulk Phase Polymerization

“…If E A.diff is neglected, because its magnitude (around 5 kJ/mol) is small compared to the activation energy of the polyreaction, E A , Equation (4) results: E A = 2 N E A.eff = 2 N 28 kJ/mol = 56 kJ/mol (4) Thus, we receive an activation energy arising from the polyreaction of around 56 kJ/mol. This value is more comparable to the activation energies resulting from slurry processes (around 70 kJ/mol).…”

“…[3,4] That applies not only for the silica supported metallocene/MAO-type catalysts, but for the propylene bulk process in general. Consequently there is no deepened understanding of this process comparable to the slurry process.…”

Reaction Calorimetric Approach to the Kinetic Investigation of the Propylene Bulk Phase Polymerization

“…On the other hand, kinetic studies concerning the propylene bulk phase polymerization process are limited in literature. [3,4] That applies not only for the silica supported metallocene/MAO-type catalysts, but for the propylene bulk process in general. Consequently there is no deepened understanding of this process comparable to the slurry process.…”