Kinetics Of 1-Decene Homogeneous Polymerization Using Metallocene/Organic Boride Catalytic System

Poly-a-olefin is a high-grade synthetic lubricant base oil, compared with the traditional mineral base oil, which has higher viscosity, lower pour point, excellent thermal stability and oxidation stability, good compatibility and non-toxic properties. It is the ideal lubricant base oil meeting the lubrication needs under harsh conditions.The kinetics of homogeneous 1-decene polymerization by metallocene catalytic system rac-Et(1-Ind)2ZrCl2/C6H5NH(CH3)2B(C6F5)4/Al(iBu)3, were studied based on experiments under different reaction conditions such as temperature and aluminum zirconium mole ratio. The intermediate sampling method connected with GC and GPC was used to obtain dynamic monomer concentration and polymer molecular weight in the batch reactor; based on the polymerization reaction mechanism and material balance, some hypotheses were made, and the kinetic model of the polymerization was established. The model includes reactions of chain initiation, chain propaganda, chain transfer to monomer, chain transfer to active center and chain termination. Levenberg-Marquardt algorithm was used to optimize the model parameters. The results of validation experiments show that the value of model prediction is close to the experimental data, and the model has good applicability for the different conditions of the reaction system.The model can predict the reaction rate, number-average and weight-average molecular weights and so on. Prediction results of the kinetic model show that the chain initiation reaction process is completed in a few seconds, the chain propagation reaction has lower activation energy than the chain transfer reactions, and higher temperature is beneficial to the chain transfer reaction, producing lower molecular weight polymer.End groups and the structure of polymer were characterized by means of nuclear magnetic resonance and infrared spectroscopy. The results showed that:In the catalyst system of 1-decene polymerization 1,2 insertion was the main form of monomer reaction,β-H elimination was the main chain transfer form, and the isotacticity of polymer is 84%. Results of GPC showed that, the molecular weight distribution of poly-1-decene is close to 2, which proved the single active center mechanism of catalyst system.