Orientation development in retensilized, biaxially oriented polypropylene films

A basic study of orientation development in retensilized, biaxially oriented polypropylene films was performed. Wide‐angle X‐ray scattering (WAXS) and birefringence measurement techniques were used to examine films prepared under specific processing conditions. Biaxial orientation factors were determined for these films and were correlated with end‐use properties of the materials. In particular, the dispensability of oriented polypropylene films was found to correlate with crystalline‐phase and amorphous‐phase orientation factors. Dispensability is a relatively important property of pressure‐sensitive tapes; it is defined as the force necessary to cut a film backing over a serrated blade of the type used in commercially available adhesive‐tape dispensers.