Since the thermoforming process typically yields large amounts of trim, it is economically vital
that the trim be reusable. Excellent polymer melt stability and the use of minimal heat by the
processor are essential for reprocessing. Thermoforming polypropylene grades need to be
formulated for maximum melt stability. To maintain the processability of the regrind, moderate
melt temperature (less than 500°F or 260°C) and typical shear history (conventional
polypropylene screw design) in the extruder are important.