Optimization of the tube extrusion die for short fiber filled polymers
Résumé
A new way to increase fiber orientation in the hoop direction in a short-fiber-filled thermoplastic tube is presented. It consists of injecting a lubricant at the surface of a diverging die. A calculation of flow and fiber orientation shows that the effect of extensional deformations which tend to orient fibers perpendicular to the flow rakes place over ail the thickness. Different dies are tested with a 30 wt% short-glass-fiber-reinforced polypropylene. Fiber orientation and mechanical properties are measured. The significance of the die is shown.