EFFECT OF EXTRUSION DIE GEOMETRY ON MOLECULAR ORIENTATION OF UNFILLED POLYETHYLENE

摘要

The effect of die geometry on molecular orientation of unfilled polyethylene has been investigated. Four dies with similar exit geometry but having a combination of two different entry angles and two land lengths have been used with a 63.5mm diameter single screw extruder. Extrudate samples were collected using a haul-off rate equivalent to the calculated die exit velocity, to prevent post-die deformation. A range of haul-off rates was also imposed. Orientation was inferred from reversion tests. Land length was found to have the greatest influence on extrudate orientation, but effects due to entry angle were also observed.