High impact polypropylene-interaction of residence time distribution, thermal deactivation and poisoning of active sites on the distribution of the ratio of rubber/polypropylene among polymer particles

A polymerization process model for the continuous production of high impact polypropylene using Ziegler-Natta and metallocene catalysts has been devel oped and this is reported herein. The novel features of the model are the i ncorporation of the effects and interactions of residence-time distribution s (RTD's) in each polymerization stage (homo and copolymerization stages), and the effects of thermal deactivation and poisoning of active sites on th e distribution of the ratio of rubber (EPR)/polypropylene (i-PP) among the polymer particles leaving the copolymerization stage. It was shown that nar rower RTD's narrow the distribution of EPR content in the polymer product. Poisoning can narrow the distribution as well. In addition, in our sample c alculations, it was observed that I-CSTR in both polymerization stages with poison can have die same effect on the distribution of EPR in the polymer product as 3-CSTR's in both stages without poison.