REACTIVE EXTRUSION OF POLYPROPYLENE .1. CONTROLLED DEGRADATION

Polypropylene was degraded by injection of a free-radical initiator during extrusion. Molecular weight distribution, molecular weight averages, and melt flow index were measured to see the effect of initiator concentration (0. 00 to 0. 04 wt%), temperature (200 and 220 degree C), and screw rpm (31 and 44). Initiator concentration was the most significant variable. In all cases, increased initiator concentration degraded the high molecular weight tail of the polypropylene and narrowed the molecular weight distribution. Melt flow index varied linearly with initiator concentration beyond 0. 01 wt% initiator. Reaction temperature had no effect on the measured properties of the extrudate.