Peroxide-controlled degradation of poly(propylene): Rheological behaviour and process modelling
Résumé
The control of the molecular weight distribution of poly(propylene) resins by peroxide degradation is widely used in polymer industry. It allows to adjust the viscosity of these resins to the level required for processing applications. The purpose of this work was to characterise the influence of peroxide degradation on the rheological behaviour of an homopolymer PP and a block copolymer PP/PE, and to use these results to obtain a predictive model of the degradation in a twin-screw extruder. By coupling a thermomechanical model of the twin-screw extrusion process, a kinetic model of the considered reactions and the rheological behaviour, it was possible to calculate the changes in molecular weight along the extruder, during the peroxide-controlled degradation.