We has carried out kinetic study on polymerization reaction of ultra-high molecular weight polyethylene by using several catalyst.
Polyethylene, for which numerous studies have been done, is one of the most important materials obtained by the petrochemical industry. The molecular weight distribution of polyethylene prepared using heterogeneous Ziegler-Natta catalysts depends on the kinds of catalyst. In general, polyethylene, obtained by unsupported Ziegler-Natta catalysts, has broad molecular weight distribution, while polymers, obtained in the supported catalyst, have different molecular weight distribution according to the nature of the active centers coated on the supports.
On the basis of precedent data, we derived a formula to determine some kinetic constants that are difficult to determine through kinetic experiments from the molecular weight distribution measurements of ultra-high molecular weight polyethylene. We also calculated the kinetic and the average lifetime of the growing chain on an active center species from kinetic data of the ethylene polymerization reaction using MgCl2/Ti(OBu)4/SiCl4/PMS/TiCl4 and the molecular weight distribution values.
Using MgCl2/Ti (OBu)4/SiCl4/PMS/TiCl4 based catalysts, the deactivation reaction mechanism was changed with time, indicating that the reaction proceeded with a bimolecular deactivation reaction mechanism for initial 20 min, and then monomolecular deactivation reaction mechanism. In the ethylene polymerization reaction, the concentration of the active center corresponding to the maximum activity was 0.133 ml/mol-Ti, 0.0714 mol/mol-Ti at 60 min, and the true deactivation rate constant at 60 min was k2=0.084 L/mol, and the chain transfer rate constant was k01=0.025 L/mol, life of chain was 66.4 s.
The results were published on "Reaction Kinetics, Mechanisms and Catalysis" with the title of "Determination of some kinetic constants in ethylene polymerization"(https://doi.org/10.1007/s11144-023-02457-1).
