Dynamic model of the copolymerization of propylene and 1-hexene with the Me2Si(2-Me-Ind)2ZrCl2 catalytic system:: Effect of 1-hexene concentration

The effect of the concentration of 1-hexene on catalytic productivity, copolymer molecular weight, and comonomer incorporation was studied and modeled for the synthesis of isotactic polypropylene copolymers by using the Me2Si(2-Me-Ind)(2)ZrCl2/ MAO catalytic system. The method of moments was employed to simulate the system and to quantify the corresponding catalytic behavior. An increase in the catalytic yield, associated with the "comonomer effect,'' together with a decrease in the copolymer average molecular weight, was found when the comonomer concentration was increased. In the range studied, a linear relation between comonomer incorporation and its concentration in the reactor was found. All these behaviors were simulated with a good fit between experimental and predicted values. An important change appears at the highest comonomer concentration studied, associated with modifications in the catalytic behavior, and the model presented here aids in quantifying this performance.