EFFECT OF ORGANIC PART OF ORGANIC/INORGANIC HYBRID SUPPORT IMMOBILIZED HYBRID CATALYST ON ETHYLENE POLYMERIZATION
有机/无机复合载体负载复合催化剂用于乙烯聚合时有机载体的作用

Organic/inorganic support made by poly(styrene-co-acrylic acid) P(S-co-AA) and SiO2 was prepared for immobilizing (n-BuCp)2ZrCl2/M-1 hybrid catalyst.P(S-co-AA) was first coated on industrialized M-1 catalyst (SiO2/MgCl2-TiCl3).The hybrid catalyst was achieved after immobilizing (n-BuCp)2ZrCl2 on the P(S-co-AA) layer.The barrier property of P(S-co-AA) layer to cocatalyst MMAO was observed by ethylene polymerization.The appearance of the lag phase in the kinetic curve during the first stage polymerization implied that the exterior catalyst ((n-BuCp)2ZrCl2) could be activated prior to the interior catalyst (M-1).In addition,the morphology,short chain branch degree,molecular weight,molecular weight distribution and crystalline property of polymers obtained at different polymerization times were investigated by scanning electron microscopy (SEM),Fourier transform infrared spectroscopy (FTIR),gel permeation chromatography (GPC),and differential scanning calorimetry (DSC),respectively.The results showed that the polymer properties had little variance in the initial polymerization stage.However,two melting peaks gradually generated when the polymerization was conducted for 40 min.Moreover,the molecular weight,molecular weight distribution and short chain branch degree showed obvious changes after 40 min of polymerization time.All of those obvious changes of the polymer properties indicated that M-1 catalyst was gradually activated by MMAO after the polymerization were conducted for 40 min.The activated M-1 catalyst led to a decrease in the molecular weight.