Molecular Weight Distribution and Melt Index Optimization in the Controlled Rheology of Polypropylene with Segregated Peroxide Addition

MARIANO ASTEASUAIN; CLAUDIA SARMORIA; ADRIANA BRANDOLIN

Ciudad de Buenos Aires, Argentina

Congreso; XXII Interamerican Congress of Chemical Engineering; 2006

Asociación Argentina de Ingenieros Químicos

Controlled rheology (CR) of polypropylene with segregated peroxide addition is a modification of classical CR, by which only a portion of the extruder throughput is degraded and then mixed with the undegraded portion. This allows independent control of melt index (MI) and molecular weight distribution (MWD) shape, which is not possible with the classical operation. In this work, a previous model of the CR of polypropylene that is able to predict the complete MWD, was updated in order to consider segregated peroxide addition and to predict melt index. This model was embedded in an optimization framework that was used to design operating conditions for simultaneously tailoring the MI and the complete MWD. Optimal values of the fraction of degraded material, operating temperature, residence time of the degrading period, and amount of initiator added to the system were obtained that allowed to modify a given virgin resin to tailor-made the final properties in terms of the MI and the high molecular weight tail.