Poly(styrene-co-acrylic acid) (PSA)/MgCl2 complex was coated on TiCl3 catalyst (SLC-S catalyst) supported on SiO2 using sol-gel method

and the Ziegler-Natta hybrid catalysts were prepared.The resulting catalysts were characterized by a series of techniques

namely Fourier transform infrared spectroscopy (FTIR)

laser scattering particle analyzer and scanning electronic microscopy (SEM).It was found that the hybrid catalysts had a core-shell structure and the thicknesses of membrane of HC-5 (PSA/SLC-S=5 wt%) catalyst and HC-20 (PSA/SLC-S=20 wt%) catalyst were 1.5 and 3 μm

respectively.Three different kinds of catalysts were used for gas phase ethylene polymerization.The effects of thickness of the membrane in hybrid catalysts on the activity and the profile of the polymerization kinetic curves of the catalysts were investigated.The results indicated that the HC-20 catalyst had a good ethylene polymerization activity and its kinetic curve was stable with an inductive period

while HC-5 catalyst demonstrated a fast decay during polymerization and its activity and kinetic curve both resembled the traditional TiCl3 catalyst.Besides

the properties of the polyethylene made by hybrid catalysts under different hydrogen contents were obtained.It is obvious that the thickness of membranes could affect the hydrogen response of the hybrid catalysts and the molecular weight distribution of the resultant polyethylene.