A nickel catalyst

his(α-naphthyl)-2

3-butanediimine nickel(Ⅱ)dichloride {[C10H7一N=C(CH3)C (CH3)=NC10H7]NiCl2} was synthesized andthen activated by methylaluminoxane(MAO)．By usingthis catalytic system branched polyethylenes(PE) of bimodal (wide) molecular weight distribution (MWD) wele prepared．The effects of various conditions

including the polymerization temperature(Tp)

ethylene pressure and nAl／nNi on the catalytic activity

molecular weight

degree of branching and branching types of PE were investigated The catalytic activity and the resulting polymer micmstructure were sensitive to the polymerization temperature．The microstructure of the resulting PE was determined by FTIR and 13C-NMR．According to Gel Permeation Chromatography(GPC)．the resulting PE exhibited a bimodal molecular weight distribution．The influence of the existence of three possible stereo isomers of the Ni single-site catalyst with unsymmetrical imino-substituted bulky ligands on the molecular weight distribUtinn was discussed.