The study on die swell, fiber length distribution, and crystallinity of PP composite through extrusion

Die swell of PP and glass fiber reinforced PP (GFRPP) through an extruder was investigated. It was observed that the die swell decreased as (1) the temperature increased, (2) the fiber content increased, and (3) the screw speed was lowered. Fiber length distribution in GFRPP was measured. The average fiber length would increase as (1) the fiber content decreased, (2) the temperature increased, and (3) the screw speed was around 25 rpm. The crystallinity of extrudate was measured by DSC and found to be independent of the screw speed and the fiber content.