Research On Properties Of Ethylene And 4-methyl-1-pentene Polymerization

Two α-diimine ligands with different steric hindrance effect were synthesized using 2,6-diisopropylaniline(2,6-dimethylaniline) and butanedione as materials by schiff reaction at room temperature, and two α-diimine nickel complexes were synthesized with with α-diimine ligands and nickel bromide as materials by complex reaction. The structures ofα-diimine ligands and α-diimine nickel complexes were characterized by infrared spectroscopy, elemental analysis, X-ray diffraction, nuclear magnetic resonance spectroscopy analysis and the results indicated that the structures of the synthetic products were In accordance with the structures of the design products.Based on the synthesis and characteration of α-diimine nickel complexes, the ethylene and 4M1 P compolymerization reaction was investigated using 2,6-diisopropylaniline bridged nickel complex and 2,6-dimethylaniline bridged nickel complex as pre-catalyst, respectively. The results showed that the two α-diimine nickel complexes had good catalytic performance in ethylene and 4M1 P compolymerization reaction. The results of the effect of polymerization parameters on the ethylene and 4M1 P compolymerization reaction showed that when the MAO was co-catalyst, the temperature was 25℃, the reaction time was 30 min, the solvent was toluene, the molar ratio of Al/Ni was 500 and the molar concentration was 0.4 mol/L, the catalytic activities of 2,6-diisopropylaniline bridged nickel complex and 2,6-dimethylaniline bridged nickel complex were 1.45×105 g/mol Ni·h and 1.80×105 g/mol Ni·h, respectively for ethylene and 4M1 P compolymerization reaction. At the same reaction conditions, the catalytic activity of 2,6-diisopropylaniline bridged nickel catalyst with large steric hindrance is lower than 2,6-dimethylaniline bridged nickel catalyst with small steric hindrance. The results of the effect of polymerization system on the ethylene and 4M1 P compolymerization reaction showed that the activity, the relative molecular mass and the branching degree for the α-diimine nickel complexes in toluene were higher than those in cyclohexane. The total branching degree of the ethylene/4M1 P copolymer was up to 38.66% using cyclohexane as solvent. The descend order of the effect of the type of co-catalysts on the catalytic activities was as follows: MAO, Et2 Al Cl and EASC. The relative molecular mass and the branching degree of the ethylene/4M1 P copolymer using Et2 Al Cl as co-catalyst were higher than those of the ethylene/4M1 P copolymer using MAO as co-catalyst. The branching degree of ethylene/4M1 P copolymer using Et2 Al Cl as co-catalyst was 6 times than that of ethylene/4M1 P copolymer using MAO as co-catalyst, and the branching degree was up to 21.57% using Et2 Al Cl as co-catalyst.