Preparation Of Spherical Magnesium Chloride Catalyst For Ethylene Polymerization

The new spherical support contained with different amount of MMT used in Ziegler-Natta catalyst was prepared by the reaction of MgCl₂, ethanol, ECH, MMT and PVP from a precipitation method. After reacting with TiCl₄ the MMT-MgCl₂-TiCl₄ catalyst was prepared. Polyethylene（PE）/montmorillonite（MMT） nanocomposites were prepared by in situ coordination polymerization by using the MMT-MgCl₂-TiCl₄ catalyst activated by Al（Et）3.During the preparation of spherical MgCl₂ support, the effects of reaction temperature,type and amount of alcohols were investigated. After observing the morphology of the support by SEM, the preferable preparation conditions were as follows: in ethanol system,80℃ of reaction temperature, n（C₂H₅OH）/n（MgCl₂）=12. During the preparation of spherical MgCl₂/MMT support, the effects of MMT addition on the morphology of the support were investigated, after observing the morphology of the support by SEM, under the premise of ensuring the composite support is spherical, the maximum amount of MMT allowed to added was m（MMT）/m（MgCl₂）=20%.During the preparation of composite MgCl₂/MMT/TiCl₄ catalyst, the MMT contained in the support and the drying condition of the support would affect the Ti content in the catalyst. Ti content in the catalyst reduce with the increase of the MMT content in the support, and while the support is not completely dry the Ti content in the catalyst would increase.The influences on the process of ethylene polymerization and the bulk density of PE/MMT nanocomposites were also studied, after the test, the best reaction condition was as follows: Al/Ti=8, the best catalyst was the one which m（MMT）/m（MgCl₂）=20%. The mechanical properties of PE/MMT nanocomposites were tested, and the tensile strength and elongation at break were improved by adding appropriate amount of MMT.