Kinetics of the propylene polymerization with prepolymerization at high temperature using Ziegler-Natta catalyst

摘要

The bulk polymerization of propylene in liquid monomers with Ziegler-Natta catalyst at 95 degrees C is studied, using alkyl aluminum as the cocatalyst and dicyclopentyldimethoxysilane as the external donor. The highest catalyst activity is shown at the cocatalyst/Ti molar ratio of 300, which keeps relatively constant with the molar ratio increasing from 300 to 800. Besides, the catalyst activity is up to 65 kgPP/(gCat*h) in the range of cocatalyst/donor molar ratio from 12 to 16. The polymerization reaction rate curves with and without catalyst precontacting are similar, while the activity with catalyst precontacting are higher than that without precontacting. Furthermore, the kinetics of polymerization with and without prepolymerization are investigated in the range of the polymerization temperature from 70 to 95 degrees C. It shows that at the high temperature, the polymerization rate increases with prepolymerization. Finally, the influence of prepolymerization at 95 degrees C on the polymerization kinetics and particle properties is also described. (C) 2014 Wiley Periodicals, Inc.