The extrusion of thin gauge sheet, defined here as having a thickness of less than 25 mils (0.63 mm), from nucleated polypropylene (PP) homopolymer can be difficult due to the rapid heat transfer and fast crystallization rate during the sheet forming/cooling process. It requires the proper extrusion equipment and special processing techniques which are explored in detail in this paper.
The extruder screw, flat die, and three roll stack must be designed specifically for thin gauge PP sheet. Successful extrusion requires careful manipulation of the following interdependent processing variables: roll temperature, melt temperature, die gap, roll gap, nip pressure, and air gap.
