Orientation development in the tubular film extrusion of polypropylene

A basic study of orientation development in the tubular film extrusion of polypropylene is reported. WAXS and birefringence measurements were carried out on films prepared under conditions of known blowup ratio B , drawdown ν L /ν O , machine direction tension, and bubble pressure. Pole figures were constructed and biaxial orientation factors determined. The use of an orientation factor triangle diagram was found to be a useful method of representing the variation of orientation with processing conditions. The variation in orientation with processing parameters for polypropylene was found to have similar behavior to that previously found for polyethylene.